Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 4664 insertions, 0 deletions

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
new file mode 100644
index 0000000000..1e08cd571d
--- /dev/null
+++ b/drivers/spi/spi.c
@@ -0,0 +1,4664 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+// SPI init/core code
+//
+// Copyright (C) 2005 David Brownell
+// Copyright (C) 2008 Secret Lab Technologies Ltd.
+
+#include <linux/acpi.h>
+#include <linux/cache.h>
+#include <linux/clk/clk-conf.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/export.h>
+#include <linux/gpio/consumer.h>
+#include <linux/highmem.h>
+#include <linux/idr.h>
+#include <linux/init.h>
+#include <linux/ioport.h>
+#include <linux/kernel.h>
+#include <linux/kthread.h>
+#include <linux/mod_devicetable.h>
+#include <linux/mutex.h>
+#include <linux/of_device.h>
+#include <linux/of_irq.h>
+#include <linux/percpu.h>
+#include <linux/platform_data/x86/apple.h>
+#include <linux/pm_domain.h>
+#include <linux/pm_runtime.h>
+#include <linux/property.h>
+#include <linux/ptp_clock_kernel.h>
+#include <linux/sched/rt.h>
+#include <linux/slab.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/spi-mem.h>
+#include <uapi/linux/sched/types.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/spi.h>
+EXPORT_TRACEPOINT_SYMBOL(spi_transfer_start);
+EXPORT_TRACEPOINT_SYMBOL(spi_transfer_stop);
+
+#include "internals.h"
+
+static DEFINE_IDR(spi_master_idr);
+
+static void spidev_release(struct device *dev)
+{
+	struct spi_device	*spi = to_spi_device(dev);
+
+	spi_controller_put(spi->controller);
+	kfree(spi->driver_override);
+	free_percpu(spi->pcpu_statistics);
+	kfree(spi);
+}
+
+static ssize_t
+modalias_show(struct device *dev, struct device_attribute *a, char *buf)
+{
+	const struct spi_device	*spi = to_spi_device(dev);
+	int len;
+
+	len = acpi_device_modalias(dev, buf, PAGE_SIZE - 1);
+	if (len != -ENODEV)
+		return len;
+
+	return sysfs_emit(buf, "%s%s\n", SPI_MODULE_PREFIX, spi->modalias);
+}
+static DEVICE_ATTR_RO(modalias);
+
+static ssize_t driver_override_store(struct device *dev,
+				     struct device_attribute *a,
+				     const char *buf, size_t count)
+{
+	struct spi_device *spi = to_spi_device(dev);
+	int ret;
+
+	ret = driver_set_override(dev, &spi->driver_override, buf, count);
+	if (ret)
+		return ret;
+
+	return count;
+}
+
+static ssize_t driver_override_show(struct device *dev,
+				    struct device_attribute *a, char *buf)
+{
+	const struct spi_device *spi = to_spi_device(dev);
+	ssize_t len;
+
+	device_lock(dev);
+	len = sysfs_emit(buf, "%s\n", spi->driver_override ? : "");
+	device_unlock(dev);
+	return len;
+}
+static DEVICE_ATTR_RW(driver_override);
+
+static struct spi_statistics __percpu *spi_alloc_pcpu_stats(struct device *dev)
+{
+	struct spi_statistics __percpu *pcpu_stats;
+
+	if (dev)
+		pcpu_stats = devm_alloc_percpu(dev, struct spi_statistics);
+	else
+		pcpu_stats = alloc_percpu_gfp(struct spi_statistics, GFP_KERNEL);
+
+	if (pcpu_stats) {
+		int cpu;
+
+		for_each_possible_cpu(cpu) {
+			struct spi_statistics *stat;
+
+			stat = per_cpu_ptr(pcpu_stats, cpu);
+			u64_stats_init(&stat->syncp);
+		}
+	}
+	return pcpu_stats;
+}
+
+static ssize_t spi_emit_pcpu_stats(struct spi_statistics __percpu *stat,
+				   char *buf, size_t offset)
+{
+	u64 val = 0;
+	int i;
+
+	for_each_possible_cpu(i) {
+		const struct spi_statistics *pcpu_stats;
+		u64_stats_t *field;
+		unsigned int start;
+		u64 inc;
+
+		pcpu_stats = per_cpu_ptr(stat, i);
+		field = (void *)pcpu_stats + offset;
+		do {
+			start = u64_stats_fetch_begin(&pcpu_stats->syncp);
+			inc = u64_stats_read(field);
+		} while (u64_stats_fetch_retry(&pcpu_stats->syncp, start));
+		val += inc;
+	}
+	return sysfs_emit(buf, "%llu\n", val);
+}
+
+#define SPI_STATISTICS_ATTRS(field, file)				\
+static ssize_t spi_controller_##field##_show(struct device *dev,	\
+					     struct device_attribute *attr, \
+					     char *buf)			\
+{									\
+	struct spi_controller *ctlr = container_of(dev,			\
+					 struct spi_controller, dev);	\
+	return spi_statistics_##field##_show(ctlr->pcpu_statistics, buf); \
+}									\
+static struct device_attribute dev_attr_spi_controller_##field = {	\
+	.attr = { .name = file, .mode = 0444 },				\
+	.show = spi_controller_##field##_show,				\
+};									\
+static ssize_t spi_device_##field##_show(struct device *dev,		\
+					 struct device_attribute *attr,	\
+					char *buf)			\
+{									\
+	struct spi_device *spi = to_spi_device(dev);			\
+	return spi_statistics_##field##_show(spi->pcpu_statistics, buf); \
+}									\
+static struct device_attribute dev_attr_spi_device_##field = {		\
+	.attr = { .name = file, .mode = 0444 },				\
+	.show = spi_device_##field##_show,				\
+}
+
+#define SPI_STATISTICS_SHOW_NAME(name, file, field)			\
+static ssize_t spi_statistics_##name##_show(struct spi_statistics __percpu *stat, \
+					    char *buf)			\
+{									\
+	return spi_emit_pcpu_stats(stat, buf,				\
+			offsetof(struct spi_statistics, field));	\
+}									\
+SPI_STATISTICS_ATTRS(name, file)
+
+#define SPI_STATISTICS_SHOW(field)					\
+	SPI_STATISTICS_SHOW_NAME(field, __stringify(field),		\
+				 field)
+
+SPI_STATISTICS_SHOW(messages);
+SPI_STATISTICS_SHOW(transfers);
+SPI_STATISTICS_SHOW(errors);
+SPI_STATISTICS_SHOW(timedout);
+
+SPI_STATISTICS_SHOW(spi_sync);
+SPI_STATISTICS_SHOW(spi_sync_immediate);
+SPI_STATISTICS_SHOW(spi_async);
+
+SPI_STATISTICS_SHOW(bytes);
+SPI_STATISTICS_SHOW(bytes_rx);
+SPI_STATISTICS_SHOW(bytes_tx);
+
+#define SPI_STATISTICS_TRANSFER_BYTES_HISTO(index, number)		\
+	SPI_STATISTICS_SHOW_NAME(transfer_bytes_histo##index,		\
+				 "transfer_bytes_histo_" number,	\
+				 transfer_bytes_histo[index])
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(0,  "0-1");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(1,  "2-3");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(2,  "4-7");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(3,  "8-15");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(4,  "16-31");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(5,  "32-63");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(6,  "64-127");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(7,  "128-255");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(8,  "256-511");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(9,  "512-1023");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(10, "1024-2047");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(11, "2048-4095");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(12, "4096-8191");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(13, "8192-16383");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(14, "16384-32767");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(15, "32768-65535");
+SPI_STATISTICS_TRANSFER_BYTES_HISTO(16, "65536+");
+
+SPI_STATISTICS_SHOW(transfers_split_maxsize);
+
+static struct attribute *spi_dev_attrs[] = {
+	&dev_attr_modalias.attr,
+	&dev_attr_driver_override.attr,
+	NULL,
+};
+
+static const struct attribute_group spi_dev_group = {
+	.attrs  = spi_dev_attrs,
+};
+
+static struct attribute *spi_device_statistics_attrs[] = {
+	&dev_attr_spi_device_messages.attr,
+	&dev_attr_spi_device_transfers.attr,
+	&dev_attr_spi_device_errors.attr,
+	&dev_attr_spi_device_timedout.attr,
+	&dev_attr_spi_device_spi_sync.attr,
+	&dev_attr_spi_device_spi_sync_immediate.attr,
+	&dev_attr_spi_device_spi_async.attr,
+	&dev_attr_spi_device_bytes.attr,
+	&dev_attr_spi_device_bytes_rx.attr,
+	&dev_attr_spi_device_bytes_tx.attr,
+	&dev_attr_spi_device_transfer_bytes_histo0.attr,
+	&dev_attr_spi_device_transfer_bytes_histo1.attr,
+	&dev_attr_spi_device_transfer_bytes_histo2.attr,
+	&dev_attr_spi_device_transfer_bytes_histo3.attr,
+	&dev_attr_spi_device_transfer_bytes_histo4.attr,
+	&dev_attr_spi_device_transfer_bytes_histo5.attr,
+	&dev_attr_spi_device_transfer_bytes_histo6.attr,
+	&dev_attr_spi_device_transfer_bytes_histo7.attr,
+	&dev_attr_spi_device_transfer_bytes_histo8.attr,
+	&dev_attr_spi_device_transfer_bytes_histo9.attr,
+	&dev_attr_spi_device_transfer_bytes_histo10.attr,
+	&dev_attr_spi_device_transfer_bytes_histo11.attr,
+	&dev_attr_spi_device_transfer_bytes_histo12.attr,
+	&dev_attr_spi_device_transfer_bytes_histo13.attr,
+	&dev_attr_spi_device_transfer_bytes_histo14.attr,
+	&dev_attr_spi_device_transfer_bytes_histo15.attr,
+	&dev_attr_spi_device_transfer_bytes_histo16.attr,
+	&dev_attr_spi_device_transfers_split_maxsize.attr,
+	NULL,
+};
+
+static const struct attribute_group spi_device_statistics_group = {
+	.name  = "statistics",
+	.attrs  = spi_device_statistics_attrs,
+};
+
+static const struct attribute_group *spi_dev_groups[] = {
+	&spi_dev_group,
+	&spi_device_statistics_group,
+	NULL,
+};
+
+static struct attribute *spi_controller_statistics_attrs[] = {
+	&dev_attr_spi_controller_messages.attr,
+	&dev_attr_spi_controller_transfers.attr,
+	&dev_attr_spi_controller_errors.attr,
+	&dev_attr_spi_controller_timedout.attr,
+	&dev_attr_spi_controller_spi_sync.attr,
+	&dev_attr_spi_controller_spi_sync_immediate.attr,
+	&dev_attr_spi_controller_spi_async.attr,
+	&dev_attr_spi_controller_bytes.attr,
+	&dev_attr_spi_controller_bytes_rx.attr,
+	&dev_attr_spi_controller_bytes_tx.attr,
+	&dev_attr_spi_controller_transfer_bytes_histo0.attr,
+	&dev_attr_spi_controller_transfer_bytes_histo1.attr,
+	&dev_attr_spi_controller_transfer_bytes_histo2.attr,
+	&dev_attr_spi_controller_transfer_bytes_histo3.attr,
+	&dev_attr_spi_controller_transfer_bytes_histo4.attr,
+	&dev_attr_spi_controller_transfer_bytes_histo5.attr,
+	&dev_attr_spi_controller_transfer_bytes_histo6.attr,
+	&dev_attr_spi_controller_transfer_bytes_histo7.attr,
+	&dev_attr_spi_controller_transfer_bytes_histo8.attr,
+	&dev_attr_spi_controller_transfer_bytes_histo9.attr,
+	&dev_attr_spi_controller_transfer_bytes_histo10.attr,
+	&dev_attr_spi_controller_transfer_bytes_histo11.attr,
+	&dev_attr_spi_controller_transfer_bytes_histo12.attr,
+	&dev_attr_spi_controller_transfer_bytes_histo13.attr,
+	&dev_attr_spi_controller_transfer_bytes_histo14.attr,
+	&dev_attr_spi_controller_transfer_bytes_histo15.attr,
+	&dev_attr_spi_controller_transfer_bytes_histo16.attr,
+	&dev_attr_spi_controller_transfers_split_maxsize.attr,
+	NULL,
+};
+
+static const struct attribute_group spi_controller_statistics_group = {
+	.name  = "statistics",
+	.attrs  = spi_controller_statistics_attrs,
+};
+
+static const struct attribute_group *spi_master_groups[] = {
+	&spi_controller_statistics_group,
+	NULL,
+};
+
+static void spi_statistics_add_transfer_stats(struct spi_statistics __percpu *pcpu_stats,
+					      struct spi_transfer *xfer,
+					      struct spi_controller *ctlr)
+{
+	int l2len = min(fls(xfer->len), SPI_STATISTICS_HISTO_SIZE) - 1;
+	struct spi_statistics *stats;
+
+	if (l2len < 0)
+		l2len = 0;
+
+	get_cpu();
+	stats = this_cpu_ptr(pcpu_stats);
+	u64_stats_update_begin(&stats->syncp);
+
+	u64_stats_inc(&stats->transfers);
+	u64_stats_inc(&stats->transfer_bytes_histo[l2len]);
+
+	u64_stats_add(&stats->bytes, xfer->len);
+	if ((xfer->tx_buf) &&
+	    (xfer->tx_buf != ctlr->dummy_tx))
+		u64_stats_add(&stats->bytes_tx, xfer->len);
+	if ((xfer->rx_buf) &&
+	    (xfer->rx_buf != ctlr->dummy_rx))
+		u64_stats_add(&stats->bytes_rx, xfer->len);
+
+	u64_stats_update_end(&stats->syncp);
+	put_cpu();
+}
+
+/*
+ * modalias support makes "modprobe $MODALIAS" new-style hotplug work,
+ * and the sysfs version makes coldplug work too.
+ */
+static const struct spi_device_id *spi_match_id(const struct spi_device_id *id, const char *name)
+{
+	while (id->name[0]) {
+		if (!strcmp(name, id->name))
+			return id;
+		id++;
+	}
+	return NULL;
+}
+
+const struct spi_device_id *spi_get_device_id(const struct spi_device *sdev)
+{
+	const struct spi_driver *sdrv = to_spi_driver(sdev->dev.driver);
+
+	return spi_match_id(sdrv->id_table, sdev->modalias);
+}
+EXPORT_SYMBOL_GPL(spi_get_device_id);
+
+const void *spi_get_device_match_data(const struct spi_device *sdev)
+{
+	const void *match;
+
+	match = device_get_match_data(&sdev->dev);
+	if (match)
+		return match;
+
+	return (const void *)spi_get_device_id(sdev)->driver_data;
+}
+EXPORT_SYMBOL_GPL(spi_get_device_match_data);
+
+static int spi_match_device(struct device *dev, struct device_driver *drv)
+{
+	const struct spi_device	*spi = to_spi_device(dev);
+	const struct spi_driver	*sdrv = to_spi_driver(drv);
+
+	/* Check override first, and if set, only use the named driver */
+	if (spi->driver_override)
+		return strcmp(spi->driver_override, drv->name) == 0;
+
+	/* Attempt an OF style match */
+	if (of_driver_match_device(dev, drv))
+		return 1;
+
+	/* Then try ACPI */
+	if (acpi_driver_match_device(dev, drv))
+		return 1;
+
+	if (sdrv->id_table)
+		return !!spi_match_id(sdrv->id_table, spi->modalias);
+
+	return strcmp(spi->modalias, drv->name) == 0;
+}
+
+static int spi_uevent(const struct device *dev, struct kobj_uevent_env *env)
+{
+	const struct spi_device		*spi = to_spi_device(dev);
+	int rc;
+
+	rc = acpi_device_uevent_modalias(dev, env);
+	if (rc != -ENODEV)
+		return rc;
+
+	return add_uevent_var(env, "MODALIAS=%s%s", SPI_MODULE_PREFIX, spi->modalias);
+}
+
+static int spi_probe(struct device *dev)
+{
+	const struct spi_driver		*sdrv = to_spi_driver(dev->driver);
+	struct spi_device		*spi = to_spi_device(dev);
+	int ret;
+
+	ret = of_clk_set_defaults(dev->of_node, false);
+	if (ret)
+		return ret;
+
+	if (dev->of_node) {
+		spi->irq = of_irq_get(dev->of_node, 0);
+		if (spi->irq == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+		if (spi->irq < 0)
+			spi->irq = 0;
+	}
+
+	ret = dev_pm_domain_attach(dev, true);
+	if (ret)
+		return ret;
+
+	if (sdrv->probe) {
+		ret = sdrv->probe(spi);
+		if (ret)
+			dev_pm_domain_detach(dev, true);
+	}
+
+	return ret;
+}
+
+static void spi_remove(struct device *dev)
+{
+	const struct spi_driver		*sdrv = to_spi_driver(dev->driver);
+
+	if (sdrv->remove)
+		sdrv->remove(to_spi_device(dev));
+
+	dev_pm_domain_detach(dev, true);
+}
+
+static void spi_shutdown(struct device *dev)
+{
+	if (dev->driver) {
+		const struct spi_driver	*sdrv = to_spi_driver(dev->driver);
+
+		if (sdrv->shutdown)
+			sdrv->shutdown(to_spi_device(dev));
+	}
+}
+
+struct bus_type spi_bus_type = {
+	.name		= "spi",
+	.dev_groups	= spi_dev_groups,
+	.match		= spi_match_device,
+	.uevent		= spi_uevent,
+	.probe		= spi_probe,
+	.remove		= spi_remove,
+	.shutdown	= spi_shutdown,
+};
+EXPORT_SYMBOL_GPL(spi_bus_type);
+
+/**
+ * __spi_register_driver - register a SPI driver
+ * @owner: owner module of the driver to register
+ * @sdrv: the driver to register
+ * Context: can sleep
+ *
+ * Return: zero on success, else a negative error code.
+ */
+int __spi_register_driver(struct module *owner, struct spi_driver *sdrv)
+{
+	sdrv->driver.owner = owner;
+	sdrv->driver.bus = &spi_bus_type;
+
+	/*
+	 * For Really Good Reasons we use spi: modaliases not of:
+	 * modaliases for DT so module autoloading won't work if we
+	 * don't have a spi_device_id as well as a compatible string.
+	 */
+	if (sdrv->driver.of_match_table) {
+		const struct of_device_id *of_id;
+
+		for (of_id = sdrv->driver.of_match_table; of_id->compatible[0];
+		     of_id++) {
+			const char *of_name;
+
+			/* Strip off any vendor prefix */
+			of_name = strnchr(of_id->compatible,
+					  sizeof(of_id->compatible), ',');
+			if (of_name)
+				of_name++;
+			else
+				of_name = of_id->compatible;
+
+			if (sdrv->id_table) {
+				const struct spi_device_id *spi_id;
+
+				spi_id = spi_match_id(sdrv->id_table, of_name);
+				if (spi_id)
+					continue;
+			} else {
+				if (strcmp(sdrv->driver.name, of_name) == 0)
+					continue;
+			}
+
+			pr_warn("SPI driver %s has no spi_device_id for %s\n",
+				sdrv->driver.name, of_id->compatible);
+		}
+	}
+
+	return driver_register(&sdrv->driver);
+}
+EXPORT_SYMBOL_GPL(__spi_register_driver);
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * SPI devices should normally not be created by SPI device drivers; that
+ * would make them board-specific.  Similarly with SPI controller drivers.
+ * Device registration normally goes into like arch/.../mach.../board-YYY.c
+ * with other readonly (flashable) information about mainboard devices.
+ */
+
+struct boardinfo {
+	struct list_head	list;
+	struct spi_board_info	board_info;
+};
+
+static LIST_HEAD(board_list);
+static LIST_HEAD(spi_controller_list);
+
+/*
+ * Used to protect add/del operation for board_info list and
+ * spi_controller list, and their matching process also used
+ * to protect object of type struct idr.
+ */
+static DEFINE_MUTEX(board_lock);
+
+/**
+ * spi_alloc_device - Allocate a new SPI device
+ * @ctlr: Controller to which device is connected
+ * Context: can sleep
+ *
+ * Allows a driver to allocate and initialize a spi_device without
+ * registering it immediately.  This allows a driver to directly
+ * fill the spi_device with device parameters before calling
+ * spi_add_device() on it.
+ *
+ * Caller is responsible to call spi_add_device() on the returned
+ * spi_device structure to add it to the SPI controller.  If the caller
+ * needs to discard the spi_device without adding it, then it should
+ * call spi_dev_put() on it.
+ *
+ * Return: a pointer to the new device, or NULL.
+ */
+struct spi_device *spi_alloc_device(struct spi_controller *ctlr)
+{
+	struct spi_device	*spi;
+
+	if (!spi_controller_get(ctlr))
+		return NULL;
+
+	spi = kzalloc(sizeof(*spi), GFP_KERNEL);
+	if (!spi) {
+		spi_controller_put(ctlr);
+		return NULL;
+	}
+
+	spi->pcpu_statistics = spi_alloc_pcpu_stats(NULL);
+	if (!spi->pcpu_statistics) {
+		kfree(spi);
+		spi_controller_put(ctlr);
+		return NULL;
+	}
+
+	spi->master = spi->controller = ctlr;
+	spi->dev.parent = &ctlr->dev;
+	spi->dev.bus = &spi_bus_type;
+	spi->dev.release = spidev_release;
+	spi->mode = ctlr->buswidth_override_bits;
+
+	device_initialize(&spi->dev);
+	return spi;
+}
+EXPORT_SYMBOL_GPL(spi_alloc_device);
+
+static void spi_dev_set_name(struct spi_device *spi)
+{
+	struct acpi_device *adev = ACPI_COMPANION(&spi->dev);
+
+	if (adev) {
+		dev_set_name(&spi->dev, "spi-%s", acpi_dev_name(adev));
+		return;
+	}
+
+	dev_set_name(&spi->dev, "%s.%u", dev_name(&spi->controller->dev),
+		     spi_get_chipselect(spi, 0));
+}
+
+static int spi_dev_check(struct device *dev, void *data)
+{
+	struct spi_device *spi = to_spi_device(dev);
+	struct spi_device *new_spi = data;
+
+	if (spi->controller == new_spi->controller &&
+	    spi_get_chipselect(spi, 0) == spi_get_chipselect(new_spi, 0))
+		return -EBUSY;
+	return 0;
+}
+
+static void spi_cleanup(struct spi_device *spi)
+{
+	if (spi->controller->cleanup)
+		spi->controller->cleanup(spi);
+}
+
+static int __spi_add_device(struct spi_device *spi)
+{
+	struct spi_controller *ctlr = spi->controller;
+	struct device *dev = ctlr->dev.parent;
+	int status;
+
+	/* Chipselects are numbered 0..max; validate. */
+	if (spi_get_chipselect(spi, 0) >= ctlr->num_chipselect) {
+		dev_err(dev, "cs%d >= max %d\n", spi_get_chipselect(spi, 0),
+			ctlr->num_chipselect);
+		return -EINVAL;
+	}
+
+	/* Set the bus ID string */
+	spi_dev_set_name(spi);
+
+	/*
+	 * We need to make sure there's no other device with this
+	 * chipselect **BEFORE** we call setup(), else we'll trash
+	 * its configuration.
+	 */
+	status = bus_for_each_dev(&spi_bus_type, NULL, spi, spi_dev_check);
+	if (status) {
+		dev_err(dev, "chipselect %d already in use\n",
+				spi_get_chipselect(spi, 0));
+		return status;
+	}
+
+	/* Controller may unregister concurrently */
+	if (IS_ENABLED(CONFIG_SPI_DYNAMIC) &&
+	    !device_is_registered(&ctlr->dev)) {
+		return -ENODEV;
+	}
+
+	if (ctlr->cs_gpiods)
+		spi_set_csgpiod(spi, 0, ctlr->cs_gpiods[spi_get_chipselect(spi, 0)]);
+
+	/*
+	 * Drivers may modify this initial i/o setup, but will
+	 * normally rely on the device being setup.  Devices
+	 * using SPI_CS_HIGH can't coexist well otherwise...
+	 */
+	status = spi_setup(spi);
+	if (status < 0) {
+		dev_err(dev, "can't setup %s, status %d\n",
+				dev_name(&spi->dev), status);
+		return status;
+	}
+
+	/* Device may be bound to an active driver when this returns */
+	status = device_add(&spi->dev);
+	if (status < 0) {
+		dev_err(dev, "can't add %s, status %d\n",
+				dev_name(&spi->dev), status);
+		spi_cleanup(spi);
+	} else {
+		dev_dbg(dev, "registered child %s\n", dev_name(&spi->dev));
+	}
+
+	return status;
+}
+
+/**
+ * spi_add_device - Add spi_device allocated with spi_alloc_device
+ * @spi: spi_device to register
+ *
+ * Companion function to spi_alloc_device.  Devices allocated with
+ * spi_alloc_device can be added onto the SPI bus with this function.
+ *
+ * Return: 0 on success; negative errno on failure
+ */
+int spi_add_device(struct spi_device *spi)
+{
+	struct spi_controller *ctlr = spi->controller;
+	int status;
+
+	mutex_lock(&ctlr->add_lock);
+	status = __spi_add_device(spi);
+	mutex_unlock(&ctlr->add_lock);
+	return status;
+}
+EXPORT_SYMBOL_GPL(spi_add_device);
+
+/**
+ * spi_new_device - instantiate one new SPI device
+ * @ctlr: Controller to which device is connected
+ * @chip: Describes the SPI device
+ * Context: can sleep
+ *
+ * On typical mainboards, this is purely internal; and it's not needed
+ * after board init creates the hard-wired devices.  Some development
+ * platforms may not be able to use spi_register_board_info though, and
+ * this is exported so that for example a USB or parport based adapter
+ * driver could add devices (which it would learn about out-of-band).
+ *
+ * Return: the new device, or NULL.
+ */
+struct spi_device *spi_new_device(struct spi_controller *ctlr,
+				  struct spi_board_info *chip)
+{
+	struct spi_device	*proxy;
+	int			status;
+
+	/*
+	 * NOTE:  caller did any chip->bus_num checks necessary.
+	 *
+	 * Also, unless we change the return value convention to use
+	 * error-or-pointer (not NULL-or-pointer), troubleshootability
+	 * suggests syslogged diagnostics are best here (ugh).
+	 */
+
+	proxy = spi_alloc_device(ctlr);
+	if (!proxy)
+		return NULL;
+
+	WARN_ON(strlen(chip->modalias) >= sizeof(proxy->modalias));
+
+	spi_set_chipselect(proxy, 0, chip->chip_select);
+	proxy->max_speed_hz = chip->max_speed_hz;
+	proxy->mode = chip->mode;
+	proxy->irq = chip->irq;
+	strscpy(proxy->modalias, chip->modalias, sizeof(proxy->modalias));
+	proxy->dev.platform_data = (void *) chip->platform_data;
+	proxy->controller_data = chip->controller_data;
+	proxy->controller_state = NULL;
+
+	if (chip->swnode) {
+		status = device_add_software_node(&proxy->dev, chip->swnode);
+		if (status) {
+			dev_err(&ctlr->dev, "failed to add software node to '%s': %d\n",
+				chip->modalias, status);
+			goto err_dev_put;
+		}
+	}
+
+	status = spi_add_device(proxy);
+	if (status < 0)
+		goto err_dev_put;
+
+	return proxy;
+
+err_dev_put:
+	device_remove_software_node(&proxy->dev);
+	spi_dev_put(proxy);
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(spi_new_device);
+
+/**
+ * spi_unregister_device - unregister a single SPI device
+ * @spi: spi_device to unregister
+ *
+ * Start making the passed SPI device vanish. Normally this would be handled
+ * by spi_unregister_controller().
+ */
+void spi_unregister_device(struct spi_device *spi)
+{
+	if (!spi)
+		return;
+
+	if (spi->dev.of_node) {
+		of_node_clear_flag(spi->dev.of_node, OF_POPULATED);
+		of_node_put(spi->dev.of_node);
+	}
+	if (ACPI_COMPANION(&spi->dev))
+		acpi_device_clear_enumerated(ACPI_COMPANION(&spi->dev));
+	device_remove_software_node(&spi->dev);
+	device_del(&spi->dev);
+	spi_cleanup(spi);
+	put_device(&spi->dev);
+}
+EXPORT_SYMBOL_GPL(spi_unregister_device);
+
+static void spi_match_controller_to_boardinfo(struct spi_controller *ctlr,
+					      struct spi_board_info *bi)
+{
+	struct spi_device *dev;
+
+	if (ctlr->bus_num != bi->bus_num)
+		return;
+
+	dev = spi_new_device(ctlr, bi);
+	if (!dev)
+		dev_err(ctlr->dev.parent, "can't create new device for %s\n",
+			bi->modalias);
+}
+
+/**
+ * spi_register_board_info - register SPI devices for a given board
+ * @info: array of chip descriptors
+ * @n: how many descriptors are provided
+ * Context: can sleep
+ *
+ * Board-specific early init code calls this (probably during arch_initcall)
+ * with segments of the SPI device table.  Any device nodes are created later,
+ * after the relevant parent SPI controller (bus_num) is defined.  We keep
+ * this table of devices forever, so that reloading a controller driver will
+ * not make Linux forget about these hard-wired devices.
+ *
+ * Other code can also call this, e.g. a particular add-on board might provide
+ * SPI devices through its expansion connector, so code initializing that board
+ * would naturally declare its SPI devices.
+ *
+ * The board info passed can safely be __initdata ... but be careful of
+ * any embedded pointers (platform_data, etc), they're copied as-is.
+ *
+ * Return: zero on success, else a negative error code.
+ */
+int spi_register_board_info(struct spi_board_info const *info, unsigned n)
+{
+	struct boardinfo *bi;
+	int i;
+
+	if (!n)
+		return 0;
+
+	bi = kcalloc(n, sizeof(*bi), GFP_KERNEL);
+	if (!bi)
+		return -ENOMEM;
+
+	for (i = 0; i < n; i++, bi++, info++) {
+		struct spi_controller *ctlr;
+
+		memcpy(&bi->board_info, info, sizeof(*info));
+
+		mutex_lock(&board_lock);
+		list_add_tail(&bi->list, &board_list);
+		list_for_each_entry(ctlr, &spi_controller_list, list)
+			spi_match_controller_to_boardinfo(ctlr,
+							  &bi->board_info);
+		mutex_unlock(&board_lock);
+	}
+
+	return 0;
+}
+
+/*-------------------------------------------------------------------------*/
+
+/* Core methods for SPI resource management */
+
+/**
+ * spi_res_alloc - allocate a spi resource that is life-cycle managed
+ *                 during the processing of a spi_message while using
+ *                 spi_transfer_one
+ * @spi:     the SPI device for which we allocate memory
+ * @release: the release code to execute for this resource
+ * @size:    size to alloc and return
+ * @gfp:     GFP allocation flags
+ *
+ * Return: the pointer to the allocated data
+ *
+ * This may get enhanced in the future to allocate from a memory pool
+ * of the @spi_device or @spi_controller to avoid repeated allocations.
+ */
+static void *spi_res_alloc(struct spi_device *spi, spi_res_release_t release,
+			   size_t size, gfp_t gfp)
+{
+	struct spi_res *sres;
+
+	sres = kzalloc(sizeof(*sres) + size, gfp);
+	if (!sres)
+		return NULL;
+
+	INIT_LIST_HEAD(&sres->entry);
+	sres->release = release;
+
+	return sres->data;
+}
+
+/**
+ * spi_res_free - free an SPI resource
+ * @res: pointer to the custom data of a resource
+ */
+static void spi_res_free(void *res)
+{
+	struct spi_res *sres = container_of(res, struct spi_res, data);
+
+	if (!res)
+		return;
+
+	WARN_ON(!list_empty(&sres->entry));
+	kfree(sres);
+}
+
+/**
+ * spi_res_add - add a spi_res to the spi_message
+ * @message: the SPI message
+ * @res:     the spi_resource
+ */
+static void spi_res_add(struct spi_message *message, void *res)
+{
+	struct spi_res *sres = container_of(res, struct spi_res, data);
+
+	WARN_ON(!list_empty(&sres->entry));
+	list_add_tail(&sres->entry, &message->resources);
+}
+
+/**
+ * spi_res_release - release all SPI resources for this message
+ * @ctlr:  the @spi_controller
+ * @message: the @spi_message
+ */
+static void spi_res_release(struct spi_controller *ctlr, struct spi_message *message)
+{
+	struct spi_res *res, *tmp;
+
+	list_for_each_entry_safe_reverse(res, tmp, &message->resources, entry) {
+		if (res->release)
+			res->release(ctlr, message, res->data);
+
+		list_del(&res->entry);
+
+		kfree(res);
+	}
+}
+
+/*-------------------------------------------------------------------------*/
+
+static void spi_set_cs(struct spi_device *spi, bool enable, bool force)
+{
+	bool activate = enable;
+
+	/*
+	 * Avoid calling into the driver (or doing delays) if the chip select
+	 * isn't actually changing from the last time this was called.
+	 */
+	if (!force && ((enable && spi->controller->last_cs == spi_get_chipselect(spi, 0)) ||
+		       (!enable && spi->controller->last_cs != spi_get_chipselect(spi, 0))) &&
+	    (spi->controller->last_cs_mode_high == (spi->mode & SPI_CS_HIGH)))
+		return;
+
+	trace_spi_set_cs(spi, activate);
+
+	spi->controller->last_cs = enable ? spi_get_chipselect(spi, 0) : -1;
+	spi->controller->last_cs_mode_high = spi->mode & SPI_CS_HIGH;
+
+	if ((spi_get_csgpiod(spi, 0) || !spi->controller->set_cs_timing) && !activate)
+		spi_delay_exec(&spi->cs_hold, NULL);
+
+	if (spi->mode & SPI_CS_HIGH)
+		enable = !enable;
+
+	if (spi_get_csgpiod(spi, 0)) {
+		if (!(spi->mode & SPI_NO_CS)) {
+			/*
+			 * Historically ACPI has no means of the GPIO polarity and
+			 * thus the SPISerialBus() resource defines it on the per-chip
+			 * basis. In order to avoid a chain of negations, the GPIO
+			 * polarity is considered being Active High. Even for the cases
+			 * when _DSD() is involved (in the updated versions of ACPI)
+			 * the GPIO CS polarity must be defined Active High to avoid
+			 * ambiguity. That's why we use enable, that takes SPI_CS_HIGH
+			 * into account.
+			 */
+			if (has_acpi_companion(&spi->dev))
+				gpiod_set_value_cansleep(spi_get_csgpiod(spi, 0), !enable);
+			else
+				/* Polarity handled by GPIO library */
+				gpiod_set_value_cansleep(spi_get_csgpiod(spi, 0), activate);
+		}
+		/* Some SPI masters need both GPIO CS & slave_select */
+		if ((spi->controller->flags & SPI_CONTROLLER_GPIO_SS) &&
+		    spi->controller->set_cs)
+			spi->controller->set_cs(spi, !enable);
+	} else if (spi->controller->set_cs) {
+		spi->controller->set_cs(spi, !enable);
+	}
+
+	if (spi_get_csgpiod(spi, 0) || !spi->controller->set_cs_timing) {
+		if (activate)
+			spi_delay_exec(&spi->cs_setup, NULL);
+		else
+			spi_delay_exec(&spi->cs_inactive, NULL);
+	}
+}
+
+#ifdef CONFIG_HAS_DMA
+static int spi_map_buf_attrs(struct spi_controller *ctlr, struct device *dev,
+			     struct sg_table *sgt, void *buf, size_t len,
+			     enum dma_data_direction dir, unsigned long attrs)
+{
+	const bool vmalloced_buf = is_vmalloc_addr(buf);
+	unsigned int max_seg_size = dma_get_max_seg_size(dev);
+#ifdef CONFIG_HIGHMEM
+	const bool kmap_buf = ((unsigned long)buf >= PKMAP_BASE &&
+				(unsigned long)buf < (PKMAP_BASE +
+					(LAST_PKMAP * PAGE_SIZE)));
+#else
+	const bool kmap_buf = false;
+#endif
+	int desc_len;
+	int sgs;
+	struct page *vm_page;
+	struct scatterlist *sg;
+	void *sg_buf;
+	size_t min;
+	int i, ret;
+
+	if (vmalloced_buf || kmap_buf) {
+		desc_len = min_t(unsigned long, max_seg_size, PAGE_SIZE);
+		sgs = DIV_ROUND_UP(len + offset_in_page(buf), desc_len);
+	} else if (virt_addr_valid(buf)) {
+		desc_len = min_t(size_t, max_seg_size, ctlr->max_dma_len);
+		sgs = DIV_ROUND_UP(len, desc_len);
+	} else {
+		return -EINVAL;
+	}
+
+	ret = sg_alloc_table(sgt, sgs, GFP_KERNEL);
+	if (ret != 0)
+		return ret;
+
+	sg = &sgt->sgl[0];
+	for (i = 0; i < sgs; i++) {
+
+		if (vmalloced_buf || kmap_buf) {
+			/*
+			 * Next scatterlist entry size is the minimum between
+			 * the desc_len and the remaining buffer length that
+			 * fits in a page.
+			 */
+			min = min_t(size_t, desc_len,
+				    min_t(size_t, len,
+					  PAGE_SIZE - offset_in_page(buf)));
+			if (vmalloced_buf)
+				vm_page = vmalloc_to_page(buf);
+			else
+				vm_page = kmap_to_page(buf);
+			if (!vm_page) {
+				sg_free_table(sgt);
+				return -ENOMEM;
+			}
+			sg_set_page(sg, vm_page,
+				    min, offset_in_page(buf));
+		} else {
+			min = min_t(size_t, len, desc_len);
+			sg_buf = buf;
+			sg_set_buf(sg, sg_buf, min);
+		}
+
+		buf += min;
+		len -= min;
+		sg = sg_next(sg);
+	}
+
+	ret = dma_map_sgtable(dev, sgt, dir, attrs);
+	if (ret < 0) {
+		sg_free_table(sgt);
+		return ret;
+	}
+
+	return 0;
+}
+
+int spi_map_buf(struct spi_controller *ctlr, struct device *dev,
+		struct sg_table *sgt, void *buf, size_t len,
+		enum dma_data_direction dir)
+{
+	return spi_map_buf_attrs(ctlr, dev, sgt, buf, len, dir, 0);
+}
+
+static void spi_unmap_buf_attrs(struct spi_controller *ctlr,
+				struct device *dev, struct sg_table *sgt,
+				enum dma_data_direction dir,
+				unsigned long attrs)
+{
+	if (sgt->orig_nents) {
+		dma_unmap_sgtable(dev, sgt, dir, attrs);
+		sg_free_table(sgt);
+		sgt->orig_nents = 0;
+		sgt->nents = 0;
+	}
+}
+
+void spi_unmap_buf(struct spi_controller *ctlr, struct device *dev,
+		   struct sg_table *sgt, enum dma_data_direction dir)
+{
+	spi_unmap_buf_attrs(ctlr, dev, sgt, dir, 0);
+}
+
+static int __spi_map_msg(struct spi_controller *ctlr, struct spi_message *msg)
+{
+	struct device *tx_dev, *rx_dev;
+	struct spi_transfer *xfer;
+	int ret;
+
+	if (!ctlr->can_dma)
+		return 0;
+
+	if (ctlr->dma_tx)
+		tx_dev = ctlr->dma_tx->device->dev;
+	else if (ctlr->dma_map_dev)
+		tx_dev = ctlr->dma_map_dev;
+	else
+		tx_dev = ctlr->dev.parent;
+
+	if (ctlr->dma_rx)
+		rx_dev = ctlr->dma_rx->device->dev;
+	else if (ctlr->dma_map_dev)
+		rx_dev = ctlr->dma_map_dev;
+	else
+		rx_dev = ctlr->dev.parent;
+
+	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+		/* The sync is done before each transfer. */
+		unsigned long attrs = DMA_ATTR_SKIP_CPU_SYNC;
+
+		if (!ctlr->can_dma(ctlr, msg->spi, xfer))
+			continue;
+
+		if (xfer->tx_buf != NULL) {
+			ret = spi_map_buf_attrs(ctlr, tx_dev, &xfer->tx_sg,
+						(void *)xfer->tx_buf,
+						xfer->len, DMA_TO_DEVICE,
+						attrs);
+			if (ret != 0)
+				return ret;
+		}
+
+		if (xfer->rx_buf != NULL) {
+			ret = spi_map_buf_attrs(ctlr, rx_dev, &xfer->rx_sg,
+						xfer->rx_buf, xfer->len,
+						DMA_FROM_DEVICE, attrs);
+			if (ret != 0) {
+				spi_unmap_buf_attrs(ctlr, tx_dev,
+						&xfer->tx_sg, DMA_TO_DEVICE,
+						attrs);
+
+				return ret;
+			}
+		}
+	}
+
+	ctlr->cur_rx_dma_dev = rx_dev;
+	ctlr->cur_tx_dma_dev = tx_dev;
+	ctlr->cur_msg_mapped = true;
+
+	return 0;
+}
+
+static int __spi_unmap_msg(struct spi_controller *ctlr, struct spi_message *msg)
+{
+	struct device *rx_dev = ctlr->cur_rx_dma_dev;
+	struct device *tx_dev = ctlr->cur_tx_dma_dev;
+	struct spi_transfer *xfer;
+
+	if (!ctlr->cur_msg_mapped || !ctlr->can_dma)
+		return 0;
+
+	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+		/* The sync has already been done after each transfer. */
+		unsigned long attrs = DMA_ATTR_SKIP_CPU_SYNC;
+
+		if (!ctlr->can_dma(ctlr, msg->spi, xfer))
+			continue;
+
+		spi_unmap_buf_attrs(ctlr, rx_dev, &xfer->rx_sg,
+				    DMA_FROM_DEVICE, attrs);
+		spi_unmap_buf_attrs(ctlr, tx_dev, &xfer->tx_sg,
+				    DMA_TO_DEVICE, attrs);
+	}
+
+	ctlr->cur_msg_mapped = false;
+
+	return 0;
+}
+
+static void spi_dma_sync_for_device(struct spi_controller *ctlr,
+				    struct spi_transfer *xfer)
+{
+	struct device *rx_dev = ctlr->cur_rx_dma_dev;
+	struct device *tx_dev = ctlr->cur_tx_dma_dev;
+
+	if (!ctlr->cur_msg_mapped)
+		return;
+
+	if (xfer->tx_sg.orig_nents)
+		dma_sync_sgtable_for_device(tx_dev, &xfer->tx_sg, DMA_TO_DEVICE);
+	if (xfer->rx_sg.orig_nents)
+		dma_sync_sgtable_for_device(rx_dev, &xfer->rx_sg, DMA_FROM_DEVICE);
+}
+
+static void spi_dma_sync_for_cpu(struct spi_controller *ctlr,
+				 struct spi_transfer *xfer)
+{
+	struct device *rx_dev = ctlr->cur_rx_dma_dev;
+	struct device *tx_dev = ctlr->cur_tx_dma_dev;
+
+	if (!ctlr->cur_msg_mapped)
+		return;
+
+	if (xfer->rx_sg.orig_nents)
+		dma_sync_sgtable_for_cpu(rx_dev, &xfer->rx_sg, DMA_FROM_DEVICE);
+	if (xfer->tx_sg.orig_nents)
+		dma_sync_sgtable_for_cpu(tx_dev, &xfer->tx_sg, DMA_TO_DEVICE);
+}
+#else /* !CONFIG_HAS_DMA */
+static inline int __spi_map_msg(struct spi_controller *ctlr,
+				struct spi_message *msg)
+{
+	return 0;
+}
+
+static inline int __spi_unmap_msg(struct spi_controller *ctlr,
+				  struct spi_message *msg)
+{
+	return 0;
+}
+
+static void spi_dma_sync_for_device(struct spi_controller *ctrl,
+				    struct spi_transfer *xfer)
+{
+}
+
+static void spi_dma_sync_for_cpu(struct spi_controller *ctrl,
+				 struct spi_transfer *xfer)
+{
+}
+#endif /* !CONFIG_HAS_DMA */
+
+static inline int spi_unmap_msg(struct spi_controller *ctlr,
+				struct spi_message *msg)
+{
+	struct spi_transfer *xfer;
+
+	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+		/*
+		 * Restore the original value of tx_buf or rx_buf if they are
+		 * NULL.
+		 */
+		if (xfer->tx_buf == ctlr->dummy_tx)
+			xfer->tx_buf = NULL;
+		if (xfer->rx_buf == ctlr->dummy_rx)
+			xfer->rx_buf = NULL;
+	}
+
+	return __spi_unmap_msg(ctlr, msg);
+}
+
+static int spi_map_msg(struct spi_controller *ctlr, struct spi_message *msg)
+{
+	struct spi_transfer *xfer;
+	void *tmp;
+	unsigned int max_tx, max_rx;
+
+	if ((ctlr->flags & (SPI_CONTROLLER_MUST_RX | SPI_CONTROLLER_MUST_TX))
+		&& !(msg->spi->mode & SPI_3WIRE)) {
+		max_tx = 0;
+		max_rx = 0;
+
+		list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+			if ((ctlr->flags & SPI_CONTROLLER_MUST_TX) &&
+			    !xfer->tx_buf)
+				max_tx = max(xfer->len, max_tx);
+			if ((ctlr->flags & SPI_CONTROLLER_MUST_RX) &&
+			    !xfer->rx_buf)
+				max_rx = max(xfer->len, max_rx);
+		}
+
+		if (max_tx) {
+			tmp = krealloc(ctlr->dummy_tx, max_tx,
+				       GFP_KERNEL | GFP_DMA | __GFP_ZERO);
+			if (!tmp)
+				return -ENOMEM;
+			ctlr->dummy_tx = tmp;
+		}
+
+		if (max_rx) {
+			tmp = krealloc(ctlr->dummy_rx, max_rx,
+				       GFP_KERNEL | GFP_DMA);
+			if (!tmp)
+				return -ENOMEM;
+			ctlr->dummy_rx = tmp;
+		}
+
+		if (max_tx || max_rx) {
+			list_for_each_entry(xfer, &msg->transfers,
+					    transfer_list) {
+				if (!xfer->len)
+					continue;
+				if (!xfer->tx_buf)
+					xfer->tx_buf = ctlr->dummy_tx;
+				if (!xfer->rx_buf)
+					xfer->rx_buf = ctlr->dummy_rx;
+			}
+		}
+	}
+
+	return __spi_map_msg(ctlr, msg);
+}
+
+static int spi_transfer_wait(struct spi_controller *ctlr,
+			     struct spi_message *msg,
+			     struct spi_transfer *xfer)
+{
+	struct spi_statistics __percpu *statm = ctlr->pcpu_statistics;
+	struct spi_statistics __percpu *stats = msg->spi->pcpu_statistics;
+	u32 speed_hz = xfer->speed_hz;
+	unsigned long long ms;
+
+	if (spi_controller_is_slave(ctlr)) {
+		if (wait_for_completion_interruptible(&ctlr->xfer_completion)) {
+			dev_dbg(&msg->spi->dev, "SPI transfer interrupted\n");
+			return -EINTR;
+		}
+	} else {
+		if (!speed_hz)
+			speed_hz = 100000;
+
+		/*
+		 * For each byte we wait for 8 cycles of the SPI clock.
+		 * Since speed is defined in Hz and we want milliseconds,
+		 * use respective multiplier, but before the division,
+		 * otherwise we may get 0 for short transfers.
+		 */
+		ms = 8LL * MSEC_PER_SEC * xfer->len;
+		do_div(ms, speed_hz);
+
+		/*
+		 * Increase it twice and add 200 ms tolerance, use
+		 * predefined maximum in case of overflow.
+		 */
+		ms += ms + 200;
+		if (ms > UINT_MAX)
+			ms = UINT_MAX;
+
+		ms = wait_for_completion_timeout(&ctlr->xfer_completion,
+						 msecs_to_jiffies(ms));
+
+		if (ms == 0) {
+			SPI_STATISTICS_INCREMENT_FIELD(statm, timedout);
+			SPI_STATISTICS_INCREMENT_FIELD(stats, timedout);
+			dev_err(&msg->spi->dev,
+				"SPI transfer timed out\n");
+			return -ETIMEDOUT;
+		}
+	}
+
+	return 0;
+}
+
+static void _spi_transfer_delay_ns(u32 ns)
+{
+	if (!ns)
+		return;
+	if (ns <= NSEC_PER_USEC) {
+		ndelay(ns);
+	} else {
+		u32 us = DIV_ROUND_UP(ns, NSEC_PER_USEC);
+
+		if (us <= 10)
+			udelay(us);
+		else
+			usleep_range(us, us + DIV_ROUND_UP(us, 10));
+	}
+}
+
+int spi_delay_to_ns(struct spi_delay *_delay, struct spi_transfer *xfer)
+{
+	u32 delay = _delay->value;
+	u32 unit = _delay->unit;
+	u32 hz;
+
+	if (!delay)
+		return 0;
+
+	switch (unit) {
+	case SPI_DELAY_UNIT_USECS:
+		delay *= NSEC_PER_USEC;
+		break;
+	case SPI_DELAY_UNIT_NSECS:
+		/* Nothing to do here */
+		break;
+	case SPI_DELAY_UNIT_SCK:
+		/* Clock cycles need to be obtained from spi_transfer */
+		if (!xfer)
+			return -EINVAL;
+		/*
+		 * If there is unknown effective speed, approximate it
+		 * by underestimating with half of the requested Hz.
+		 */
+		hz = xfer->effective_speed_hz ?: xfer->speed_hz / 2;
+		if (!hz)
+			return -EINVAL;
+
+		/* Convert delay to nanoseconds */
+		delay *= DIV_ROUND_UP(NSEC_PER_SEC, hz);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return delay;
+}
+EXPORT_SYMBOL_GPL(spi_delay_to_ns);
+
+int spi_delay_exec(struct spi_delay *_delay, struct spi_transfer *xfer)
+{
+	int delay;
+
+	might_sleep();
+
+	if (!_delay)
+		return -EINVAL;
+
+	delay = spi_delay_to_ns(_delay, xfer);
+	if (delay < 0)
+		return delay;
+
+	_spi_transfer_delay_ns(delay);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(spi_delay_exec);
+
+static void _spi_transfer_cs_change_delay(struct spi_message *msg,
+					  struct spi_transfer *xfer)
+{
+	u32 default_delay_ns = 10 * NSEC_PER_USEC;
+	u32 delay = xfer->cs_change_delay.value;
+	u32 unit = xfer->cs_change_delay.unit;
+	int ret;
+
+	/* Return early on "fast" mode - for everything but USECS */
+	if (!delay) {
+		if (unit == SPI_DELAY_UNIT_USECS)
+			_spi_transfer_delay_ns(default_delay_ns);
+		return;
+	}
+
+	ret = spi_delay_exec(&xfer->cs_change_delay, xfer);
+	if (ret) {
+		dev_err_once(&msg->spi->dev,
+			     "Use of unsupported delay unit %i, using default of %luus\n",
+			     unit, default_delay_ns / NSEC_PER_USEC);
+		_spi_transfer_delay_ns(default_delay_ns);
+	}
+}
+
+void spi_transfer_cs_change_delay_exec(struct spi_message *msg,
+						  struct spi_transfer *xfer)
+{
+	_spi_transfer_cs_change_delay(msg, xfer);
+}
+EXPORT_SYMBOL_GPL(spi_transfer_cs_change_delay_exec);
+
+/*
+ * spi_transfer_one_message - Default implementation of transfer_one_message()
+ *
+ * This is a standard implementation of transfer_one_message() for
+ * drivers which implement a transfer_one() operation.  It provides
+ * standard handling of delays and chip select management.
+ */
+static int spi_transfer_one_message(struct spi_controller *ctlr,
+				    struct spi_message *msg)
+{
+	struct spi_transfer *xfer;
+	bool keep_cs = false;
+	int ret = 0;
+	struct spi_statistics __percpu *statm = ctlr->pcpu_statistics;
+	struct spi_statistics __percpu *stats = msg->spi->pcpu_statistics;
+
+	xfer = list_first_entry(&msg->transfers, struct spi_transfer, transfer_list);
+	spi_set_cs(msg->spi, !xfer->cs_off, false);
+
+	SPI_STATISTICS_INCREMENT_FIELD(statm, messages);
+	SPI_STATISTICS_INCREMENT_FIELD(stats, messages);
+
+	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+		trace_spi_transfer_start(msg, xfer);
+
+		spi_statistics_add_transfer_stats(statm, xfer, ctlr);
+		spi_statistics_add_transfer_stats(stats, xfer, ctlr);
+
+		if (!ctlr->ptp_sts_supported) {
+			xfer->ptp_sts_word_pre = 0;
+			ptp_read_system_prets(xfer->ptp_sts);
+		}
+
+		if ((xfer->tx_buf || xfer->rx_buf) && xfer->len) {
+			reinit_completion(&ctlr->xfer_completion);
+
+fallback_pio:
+			spi_dma_sync_for_device(ctlr, xfer);
+			ret = ctlr->transfer_one(ctlr, msg->spi, xfer);
+			if (ret < 0) {
+				spi_dma_sync_for_cpu(ctlr, xfer);
+
+				if (ctlr->cur_msg_mapped &&
+				   (xfer->error & SPI_TRANS_FAIL_NO_START)) {
+					__spi_unmap_msg(ctlr, msg);
+					ctlr->fallback = true;
+					xfer->error &= ~SPI_TRANS_FAIL_NO_START;
+					goto fallback_pio;
+				}
+
+				SPI_STATISTICS_INCREMENT_FIELD(statm,
+							       errors);
+				SPI_STATISTICS_INCREMENT_FIELD(stats,
+							       errors);
+				dev_err(&msg->spi->dev,
+					"SPI transfer failed: %d\n", ret);
+				goto out;
+			}
+
+			if (ret > 0) {
+				ret = spi_transfer_wait(ctlr, msg, xfer);
+				if (ret < 0)
+					msg->status = ret;
+			}
+
+			spi_dma_sync_for_cpu(ctlr, xfer);
+		} else {
+			if (xfer->len)
+				dev_err(&msg->spi->dev,
+					"Bufferless transfer has length %u\n",
+					xfer->len);
+		}
+
+		if (!ctlr->ptp_sts_supported) {
+			ptp_read_system_postts(xfer->ptp_sts);
+			xfer->ptp_sts_word_post = xfer->len;
+		}
+
+		trace_spi_transfer_stop(msg, xfer);
+
+		if (msg->status != -EINPROGRESS)
+			goto out;
+
+		spi_transfer_delay_exec(xfer);
+
+		if (xfer->cs_change) {
+			if (list_is_last(&xfer->transfer_list,
+					 &msg->transfers)) {
+				keep_cs = true;
+			} else {
+				if (!xfer->cs_off)
+					spi_set_cs(msg->spi, false, false);
+				_spi_transfer_cs_change_delay(msg, xfer);
+				if (!list_next_entry(xfer, transfer_list)->cs_off)
+					spi_set_cs(msg->spi, true, false);
+			}
+		} else if (!list_is_last(&xfer->transfer_list, &msg->transfers) &&
+			   xfer->cs_off != list_next_entry(xfer, transfer_list)->cs_off) {
+			spi_set_cs(msg->spi, xfer->cs_off, false);
+		}
+
+		msg->actual_length += xfer->len;
+	}
+
+out:
+	if (ret != 0 || !keep_cs)
+		spi_set_cs(msg->spi, false, false);
+
+	if (msg->status == -EINPROGRESS)
+		msg->status = ret;
+
+	if (msg->status && ctlr->handle_err)
+		ctlr->handle_err(ctlr, msg);
+
+	spi_finalize_current_message(ctlr);
+
+	return ret;
+}
+
+/**
+ * spi_finalize_current_transfer - report completion of a transfer
+ * @ctlr: the controller reporting completion
+ *
+ * Called by SPI drivers using the core transfer_one_message()
+ * implementation to notify it that the current interrupt driven
+ * transfer has finished and the next one may be scheduled.
+ */
+void spi_finalize_current_transfer(struct spi_controller *ctlr)
+{
+	complete(&ctlr->xfer_completion);
+}
+EXPORT_SYMBOL_GPL(spi_finalize_current_transfer);
+
+static void spi_idle_runtime_pm(struct spi_controller *ctlr)
+{
+	if (ctlr->auto_runtime_pm) {
+		pm_runtime_mark_last_busy(ctlr->dev.parent);
+		pm_runtime_put_autosuspend(ctlr->dev.parent);
+	}
+}
+
+static int __spi_pump_transfer_message(struct spi_controller *ctlr,
+		struct spi_message *msg, bool was_busy)
+{
+	struct spi_transfer *xfer;
+	int ret;
+
+	if (!was_busy && ctlr->auto_runtime_pm) {
+		ret = pm_runtime_get_sync(ctlr->dev.parent);
+		if (ret < 0) {
+			pm_runtime_put_noidle(ctlr->dev.parent);
+			dev_err(&ctlr->dev, "Failed to power device: %d\n",
+				ret);
+
+			msg->status = ret;
+			spi_finalize_current_message(ctlr);
+
+			return ret;
+		}
+	}
+
+	if (!was_busy)
+		trace_spi_controller_busy(ctlr);
+
+	if (!was_busy && ctlr->prepare_transfer_hardware) {
+		ret = ctlr->prepare_transfer_hardware(ctlr);
+		if (ret) {
+			dev_err(&ctlr->dev,
+				"failed to prepare transfer hardware: %d\n",
+				ret);
+
+			if (ctlr->auto_runtime_pm)
+				pm_runtime_put(ctlr->dev.parent);
+
+			msg->status = ret;
+			spi_finalize_current_message(ctlr);
+
+			return ret;
+		}
+	}
+
+	trace_spi_message_start(msg);
+
+	ret = spi_split_transfers_maxsize(ctlr, msg,
+					  spi_max_transfer_size(msg->spi),
+					  GFP_KERNEL | GFP_DMA);
+	if (ret) {
+		msg->status = ret;
+		spi_finalize_current_message(ctlr);
+		return ret;
+	}
+
+	if (ctlr->prepare_message) {
+		ret = ctlr->prepare_message(ctlr, msg);
+		if (ret) {
+			dev_err(&ctlr->dev, "failed to prepare message: %d\n",
+				ret);
+			msg->status = ret;
+			spi_finalize_current_message(ctlr);
+			return ret;
+		}
+		msg->prepared = true;
+	}
+
+	ret = spi_map_msg(ctlr, msg);
+	if (ret) {
+		msg->status = ret;
+		spi_finalize_current_message(ctlr);
+		return ret;
+	}
+
+	if (!ctlr->ptp_sts_supported && !ctlr->transfer_one) {
+		list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+			xfer->ptp_sts_word_pre = 0;
+			ptp_read_system_prets(xfer->ptp_sts);
+		}
+	}
+
+	/*
+	 * Drivers implementation of transfer_one_message() must arrange for
+	 * spi_finalize_current_message() to get called. Most drivers will do
+	 * this in the calling context, but some don't. For those cases, a
+	 * completion is used to guarantee that this function does not return
+	 * until spi_finalize_current_message() is done accessing
+	 * ctlr->cur_msg.
+	 * Use of the following two flags enable to opportunistically skip the
+	 * use of the completion since its use involves expensive spin locks.
+	 * In case of a race with the context that calls
+	 * spi_finalize_current_message() the completion will always be used,
+	 * due to strict ordering of these flags using barriers.
+	 */
+	WRITE_ONCE(ctlr->cur_msg_incomplete, true);
+	WRITE_ONCE(ctlr->cur_msg_need_completion, false);
+	reinit_completion(&ctlr->cur_msg_completion);
+	smp_wmb(); /* Make these available to spi_finalize_current_message() */
+
+	ret = ctlr->transfer_one_message(ctlr, msg);
+	if (ret) {
+		dev_err(&ctlr->dev,
+			"failed to transfer one message from queue\n");
+		return ret;
+	}
+
+	WRITE_ONCE(ctlr->cur_msg_need_completion, true);
+	smp_mb(); /* See spi_finalize_current_message()... */
+	if (READ_ONCE(ctlr->cur_msg_incomplete))
+		wait_for_completion(&ctlr->cur_msg_completion);
+
+	return 0;
+}
+
+/**
+ * __spi_pump_messages - function which processes SPI message queue
+ * @ctlr: controller to process queue for
+ * @in_kthread: true if we are in the context of the message pump thread
+ *
+ * This function checks if there is any SPI message in the queue that
+ * needs processing and if so call out to the driver to initialize hardware
+ * and transfer each message.
+ *
+ * Note that it is called both from the kthread itself and also from
+ * inside spi_sync(); the queue extraction handling at the top of the
+ * function should deal with this safely.
+ */
+static void __spi_pump_messages(struct spi_controller *ctlr, bool in_kthread)
+{
+	struct spi_message *msg;
+	bool was_busy = false;
+	unsigned long flags;
+	int ret;
+
+	/* Take the I/O mutex */
+	mutex_lock(&ctlr->io_mutex);
+
+	/* Lock queue */
+	spin_lock_irqsave(&ctlr->queue_lock, flags);
+
+	/* Make sure we are not already running a message */
+	if (ctlr->cur_msg)
+		goto out_unlock;
+
+	/* Check if the queue is idle */
+	if (list_empty(&ctlr->queue) || !ctlr->running) {
+		if (!ctlr->busy)
+			goto out_unlock;
+
+		/* Defer any non-atomic teardown to the thread */
+		if (!in_kthread) {
+			if (!ctlr->dummy_rx && !ctlr->dummy_tx &&
+			    !ctlr->unprepare_transfer_hardware) {
+				spi_idle_runtime_pm(ctlr);
+				ctlr->busy = false;
+				ctlr->queue_empty = true;
+				trace_spi_controller_idle(ctlr);
+			} else {
+				kthread_queue_work(ctlr->kworker,
+						   &ctlr->pump_messages);
+			}
+			goto out_unlock;
+		}
+
+		ctlr->busy = false;
+		spin_unlock_irqrestore(&ctlr->queue_lock, flags);
+
+		kfree(ctlr->dummy_rx);
+		ctlr->dummy_rx = NULL;
+		kfree(ctlr->dummy_tx);
+		ctlr->dummy_tx = NULL;
+		if (ctlr->unprepare_transfer_hardware &&
+		    ctlr->unprepare_transfer_hardware(ctlr))
+			dev_err(&ctlr->dev,
+				"failed to unprepare transfer hardware\n");
+		spi_idle_runtime_pm(ctlr);
+		trace_spi_controller_idle(ctlr);
+
+		spin_lock_irqsave(&ctlr->queue_lock, flags);
+		ctlr->queue_empty = true;
+		goto out_unlock;
+	}
+
+	/* Extract head of queue */
+	msg = list_first_entry(&ctlr->queue, struct spi_message, queue);
+	ctlr->cur_msg = msg;
+
+	list_del_init(&msg->queue);
+	if (ctlr->busy)
+		was_busy = true;
+	else
+		ctlr->busy = true;
+	spin_unlock_irqrestore(&ctlr->queue_lock, flags);
+
+	ret = __spi_pump_transfer_message(ctlr, msg, was_busy);
+	kthread_queue_work(ctlr->kworker, &ctlr->pump_messages);
+
+	ctlr->cur_msg = NULL;
+	ctlr->fallback = false;
+
+	mutex_unlock(&ctlr->io_mutex);
+
+	/* Prod the scheduler in case transfer_one() was busy waiting */
+	if (!ret)
+		cond_resched();
+	return;
+
+out_unlock:
+	spin_unlock_irqrestore(&ctlr->queue_lock, flags);
+	mutex_unlock(&ctlr->io_mutex);
+}
+
+/**
+ * spi_pump_messages - kthread work function which processes spi message queue
+ * @work: pointer to kthread work struct contained in the controller struct
+ */
+static void spi_pump_messages(struct kthread_work *work)
+{
+	struct spi_controller *ctlr =
+		container_of(work, struct spi_controller, pump_messages);
+
+	__spi_pump_messages(ctlr, true);
+}
+
+/**
+ * spi_take_timestamp_pre - helper to collect the beginning of the TX timestamp
+ * @ctlr: Pointer to the spi_controller structure of the driver
+ * @xfer: Pointer to the transfer being timestamped
+ * @progress: How many words (not bytes) have been transferred so far
+ * @irqs_off: If true, will disable IRQs and preemption for the duration of the
+ *	      transfer, for less jitter in time measurement. Only compatible
+ *	      with PIO drivers. If true, must follow up with
+ *	      spi_take_timestamp_post or otherwise system will crash.
+ *	      WARNING: for fully predictable results, the CPU frequency must
+ *	      also be under control (governor).
+ *
+ * This is a helper for drivers to collect the beginning of the TX timestamp
+ * for the requested byte from the SPI transfer. The frequency with which this
+ * function must be called (once per word, once for the whole transfer, once
+ * per batch of words etc) is arbitrary as long as the @tx buffer offset is
+ * greater than or equal to the requested byte at the time of the call. The
+ * timestamp is only taken once, at the first such call. It is assumed that
+ * the driver advances its @tx buffer pointer monotonically.
+ */
+void spi_take_timestamp_pre(struct spi_controller *ctlr,
+			    struct spi_transfer *xfer,
+			    size_t progress, bool irqs_off)
+{
+	if (!xfer->ptp_sts)
+		return;
+
+	if (xfer->timestamped)
+		return;
+
+	if (progress > xfer->ptp_sts_word_pre)
+		return;
+
+	/* Capture the resolution of the timestamp */
+	xfer->ptp_sts_word_pre = progress;
+
+	if (irqs_off) {
+		local_irq_save(ctlr->irq_flags);
+		preempt_disable();
+	}
+
+	ptp_read_system_prets(xfer->ptp_sts);
+}
+EXPORT_SYMBOL_GPL(spi_take_timestamp_pre);
+
+/**
+ * spi_take_timestamp_post - helper to collect the end of the TX timestamp
+ * @ctlr: Pointer to the spi_controller structure of the driver
+ * @xfer: Pointer to the transfer being timestamped
+ * @progress: How many words (not bytes) have been transferred so far
+ * @irqs_off: If true, will re-enable IRQs and preemption for the local CPU.
+ *
+ * This is a helper for drivers to collect the end of the TX timestamp for
+ * the requested byte from the SPI transfer. Can be called with an arbitrary
+ * frequency: only the first call where @tx exceeds or is equal to the
+ * requested word will be timestamped.
+ */
+void spi_take_timestamp_post(struct spi_controller *ctlr,
+			     struct spi_transfer *xfer,
+			     size_t progress, bool irqs_off)
+{
+	if (!xfer->ptp_sts)
+		return;
+
+	if (xfer->timestamped)
+		return;
+
+	if (progress < xfer->ptp_sts_word_post)
+		return;
+
+	ptp_read_system_postts(xfer->ptp_sts);
+
+	if (irqs_off) {
+		local_irq_restore(ctlr->irq_flags);
+		preempt_enable();
+	}
+
+	/* Capture the resolution of the timestamp */
+	xfer->ptp_sts_word_post = progress;
+
+	xfer->timestamped = 1;
+}
+EXPORT_SYMBOL_GPL(spi_take_timestamp_post);
+
+/**
+ * spi_set_thread_rt - set the controller to pump at realtime priority
+ * @ctlr: controller to boost priority of
+ *
+ * This can be called because the controller requested realtime priority
+ * (by setting the ->rt value before calling spi_register_controller()) or
+ * because a device on the bus said that its transfers needed realtime
+ * priority.
+ *
+ * NOTE: at the moment if any device on a bus says it needs realtime then
+ * the thread will be at realtime priority for all transfers on that
+ * controller.  If this eventually becomes a problem we may see if we can
+ * find a way to boost the priority only temporarily during relevant
+ * transfers.
+ */
+static void spi_set_thread_rt(struct spi_controller *ctlr)
+{
+	dev_info(&ctlr->dev,
+		"will run message pump with realtime priority\n");
+	sched_set_fifo(ctlr->kworker->task);
+}
+
+static int spi_init_queue(struct spi_controller *ctlr)
+{
+	ctlr->running = false;
+	ctlr->busy = false;
+	ctlr->queue_empty = true;
+
+	ctlr->kworker = kthread_create_worker(0, dev_name(&ctlr->dev));
+	if (IS_ERR(ctlr->kworker)) {
+		dev_err(&ctlr->dev, "failed to create message pump kworker\n");
+		return PTR_ERR(ctlr->kworker);
+	}
+
+	kthread_init_work(&ctlr->pump_messages, spi_pump_messages);
+
+	/*
+	 * Controller config will indicate if this controller should run the
+	 * message pump with high (realtime) priority to reduce the transfer
+	 * latency on the bus by minimising the delay between a transfer
+	 * request and the scheduling of the message pump thread. Without this
+	 * setting the message pump thread will remain at default priority.
+	 */
+	if (ctlr->rt)
+		spi_set_thread_rt(ctlr);
+
+	return 0;
+}
+
+/**
+ * spi_get_next_queued_message() - called by driver to check for queued
+ * messages
+ * @ctlr: the controller to check for queued messages
+ *
+ * If there are more messages in the queue, the next message is returned from
+ * this call.
+ *
+ * Return: the next message in the queue, else NULL if the queue is empty.
+ */
+struct spi_message *spi_get_next_queued_message(struct spi_controller *ctlr)
+{
+	struct spi_message *next;
+	unsigned long flags;
+
+	/* Get a pointer to the next message, if any */
+	spin_lock_irqsave(&ctlr->queue_lock, flags);
+	next = list_first_entry_or_null(&ctlr->queue, struct spi_message,
+					queue);
+	spin_unlock_irqrestore(&ctlr->queue_lock, flags);
+
+	return next;
+}
+EXPORT_SYMBOL_GPL(spi_get_next_queued_message);
+
+/**
+ * spi_finalize_current_message() - the current message is complete
+ * @ctlr: the controller to return the message to
+ *
+ * Called by the driver to notify the core that the message in the front of the
+ * queue is complete and can be removed from the queue.
+ */
+void spi_finalize_current_message(struct spi_controller *ctlr)
+{
+	struct spi_transfer *xfer;
+	struct spi_message *mesg;
+	int ret;
+
+	mesg = ctlr->cur_msg;
+
+	if (!ctlr->ptp_sts_supported && !ctlr->transfer_one) {
+		list_for_each_entry(xfer, &mesg->transfers, transfer_list) {
+			ptp_read_system_postts(xfer->ptp_sts);
+			xfer->ptp_sts_word_post = xfer->len;
+		}
+	}
+
+	if (unlikely(ctlr->ptp_sts_supported))
+		list_for_each_entry(xfer, &mesg->transfers, transfer_list)
+			WARN_ON_ONCE(xfer->ptp_sts && !xfer->timestamped);
+
+	spi_unmap_msg(ctlr, mesg);
+
+	/*
+	 * In the prepare_messages callback the SPI bus has the opportunity
+	 * to split a transfer to smaller chunks.
+	 *
+	 * Release the split transfers here since spi_map_msg() is done on
+	 * the split transfers.
+	 */
+	spi_res_release(ctlr, mesg);
+
+	if (mesg->prepared && ctlr->unprepare_message) {
+		ret = ctlr->unprepare_message(ctlr, mesg);
+		if (ret) {
+			dev_err(&ctlr->dev, "failed to unprepare message: %d\n",
+				ret);
+		}
+	}
+
+	mesg->prepared = false;
+
+	WRITE_ONCE(ctlr->cur_msg_incomplete, false);
+	smp_mb(); /* See __spi_pump_transfer_message()... */
+	if (READ_ONCE(ctlr->cur_msg_need_completion))
+		complete(&ctlr->cur_msg_completion);
+
+	trace_spi_message_done(mesg);
+
+	mesg->state = NULL;
+	if (mesg->complete)
+		mesg->complete(mesg->context);
+}
+EXPORT_SYMBOL_GPL(spi_finalize_current_message);
+
+static int spi_start_queue(struct spi_controller *ctlr)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&ctlr->queue_lock, flags);
+
+	if (ctlr->running || ctlr->busy) {
+		spin_unlock_irqrestore(&ctlr->queue_lock, flags);
+		return -EBUSY;
+	}
+
+	ctlr->running = true;
+	ctlr->cur_msg = NULL;
+	spin_unlock_irqrestore(&ctlr->queue_lock, flags);
+
+	kthread_queue_work(ctlr->kworker, &ctlr->pump_messages);
+
+	return 0;
+}
+
+static int spi_stop_queue(struct spi_controller *ctlr)
+{
+	unsigned long flags;
+	unsigned limit = 500;
+	int ret = 0;
+
+	spin_lock_irqsave(&ctlr->queue_lock, flags);
+
+	/*
+	 * This is a bit lame, but is optimized for the common execution path.
+	 * A wait_queue on the ctlr->busy could be used, but then the common
+	 * execution path (pump_messages) would be required to call wake_up or
+	 * friends on every SPI message. Do this instead.
+	 */
+	while ((!list_empty(&ctlr->queue) || ctlr->busy) && limit--) {
+		spin_unlock_irqrestore(&ctlr->queue_lock, flags);
+		usleep_range(10000, 11000);
+		spin_lock_irqsave(&ctlr->queue_lock, flags);
+	}
+
+	if (!list_empty(&ctlr->queue) || ctlr->busy)
+		ret = -EBUSY;
+	else
+		ctlr->running = false;
+
+	spin_unlock_irqrestore(&ctlr->queue_lock, flags);
+
+	if (ret) {
+		dev_warn(&ctlr->dev, "could not stop message queue\n");
+		return ret;
+	}
+	return ret;
+}
+
+static int spi_destroy_queue(struct spi_controller *ctlr)
+{
+	int ret;
+
+	ret = spi_stop_queue(ctlr);
+
+	/*
+	 * kthread_flush_worker will block until all work is done.
+	 * If the reason that stop_queue timed out is that the work will never
+	 * finish, then it does no good to call flush/stop thread, so
+	 * return anyway.
+	 */
+	if (ret) {
+		dev_err(&ctlr->dev, "problem destroying queue\n");
+		return ret;
+	}
+
+	kthread_destroy_worker(ctlr->kworker);
+
+	return 0;
+}
+
+static int __spi_queued_transfer(struct spi_device *spi,
+				 struct spi_message *msg,
+				 bool need_pump)
+{
+	struct spi_controller *ctlr = spi->controller;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ctlr->queue_lock, flags);
+
+	if (!ctlr->running) {
+		spin_unlock_irqrestore(&ctlr->queue_lock, flags);
+		return -ESHUTDOWN;
+	}
+	msg->actual_length = 0;
+	msg->status = -EINPROGRESS;
+
+	list_add_tail(&msg->queue, &ctlr->queue);
+	ctlr->queue_empty = false;
+	if (!ctlr->busy && need_pump)
+		kthread_queue_work(ctlr->kworker, &ctlr->pump_messages);
+
+	spin_unlock_irqrestore(&ctlr->queue_lock, flags);
+	return 0;
+}
+
+/**
+ * spi_queued_transfer - transfer function for queued transfers
+ * @spi: SPI device which is requesting transfer
+ * @msg: SPI message which is to handled is queued to driver queue
+ *
+ * Return: zero on success, else a negative error code.
+ */
+static int spi_queued_transfer(struct spi_device *spi, struct spi_message *msg)
+{
+	return __spi_queued_transfer(spi, msg, true);
+}
+
+static int spi_controller_initialize_queue(struct spi_controller *ctlr)
+{
+	int ret;
+
+	ctlr->transfer = spi_queued_transfer;
+	if (!ctlr->transfer_one_message)
+		ctlr->transfer_one_message = spi_transfer_one_message;
+
+	/* Initialize and start queue */
+	ret = spi_init_queue(ctlr);
+	if (ret) {
+		dev_err(&ctlr->dev, "problem initializing queue\n");
+		goto err_init_queue;
+	}
+	ctlr->queued = true;
+	ret = spi_start_queue(ctlr);
+	if (ret) {
+		dev_err(&ctlr->dev, "problem starting queue\n");
+		goto err_start_queue;
+	}
+
+	return 0;
+
+err_start_queue:
+	spi_destroy_queue(ctlr);
+err_init_queue:
+	return ret;
+}
+
+/**
+ * spi_flush_queue - Send all pending messages in the queue from the callers'
+ *		     context
+ * @ctlr: controller to process queue for
+ *
+ * This should be used when one wants to ensure all pending messages have been
+ * sent before doing something. Is used by the spi-mem code to make sure SPI
+ * memory operations do not preempt regular SPI transfers that have been queued
+ * before the spi-mem operation.
+ */
+void spi_flush_queue(struct spi_controller *ctlr)
+{
+	if (ctlr->transfer == spi_queued_transfer)
+		__spi_pump_messages(ctlr, false);
+}
+
+/*-------------------------------------------------------------------------*/
+
+#if defined(CONFIG_OF)
+static void of_spi_parse_dt_cs_delay(struct device_node *nc,
+				     struct spi_delay *delay, const char *prop)
+{
+	u32 value;
+
+	if (!of_property_read_u32(nc, prop, &value)) {
+		if (value > U16_MAX) {
+			delay->value = DIV_ROUND_UP(value, 1000);
+			delay->unit = SPI_DELAY_UNIT_USECS;
+		} else {
+			delay->value = value;
+			delay->unit = SPI_DELAY_UNIT_NSECS;
+		}
+	}
+}
+
+static int of_spi_parse_dt(struct spi_controller *ctlr, struct spi_device *spi,
+			   struct device_node *nc)
+{
+	u32 value;
+	int rc;
+
+	/* Mode (clock phase/polarity/etc.) */
+	if (of_property_read_bool(nc, "spi-cpha"))
+		spi->mode |= SPI_CPHA;
+	if (of_property_read_bool(nc, "spi-cpol"))
+		spi->mode |= SPI_CPOL;
+	if (of_property_read_bool(nc, "spi-3wire"))
+		spi->mode |= SPI_3WIRE;
+	if (of_property_read_bool(nc, "spi-lsb-first"))
+		spi->mode |= SPI_LSB_FIRST;
+	if (of_property_read_bool(nc, "spi-cs-high"))
+		spi->mode |= SPI_CS_HIGH;
+
+	/* Device DUAL/QUAD mode */
+	if (!of_property_read_u32(nc, "spi-tx-bus-width", &value)) {
+		switch (value) {
+		case 0:
+			spi->mode |= SPI_NO_TX;
+			break;
+		case 1:
+			break;
+		case 2:
+			spi->mode |= SPI_TX_DUAL;
+			break;
+		case 4:
+			spi->mode |= SPI_TX_QUAD;
+			break;
+		case 8:
+			spi->mode |= SPI_TX_OCTAL;
+			break;
+		default:
+			dev_warn(&ctlr->dev,
+				"spi-tx-bus-width %d not supported\n",
+				value);
+			break;
+		}
+	}
+
+	if (!of_property_read_u32(nc, "spi-rx-bus-width", &value)) {
+		switch (value) {
+		case 0:
+			spi->mode |= SPI_NO_RX;
+			break;
+		case 1:
+			break;
+		case 2:
+			spi->mode |= SPI_RX_DUAL;
+			break;
+		case 4:
+			spi->mode |= SPI_RX_QUAD;
+			break;
+		case 8:
+			spi->mode |= SPI_RX_OCTAL;
+			break;
+		default:
+			dev_warn(&ctlr->dev,
+				"spi-rx-bus-width %d not supported\n",
+				value);
+			break;
+		}
+	}
+
+	if (spi_controller_is_slave(ctlr)) {
+		if (!of_node_name_eq(nc, "slave")) {
+			dev_err(&ctlr->dev, "%pOF is not called 'slave'\n",
+				nc);
+			return -EINVAL;
+		}
+		return 0;
+	}
+
+	/* Device address */
+	rc = of_property_read_u32(nc, "reg", &value);
+	if (rc) {
+		dev_err(&ctlr->dev, "%pOF has no valid 'reg' property (%d)\n",
+			nc, rc);
+		return rc;
+	}
+	spi_set_chipselect(spi, 0, value);
+
+	/* Device speed */
+	if (!of_property_read_u32(nc, "spi-max-frequency", &value))
+		spi->max_speed_hz = value;
+
+	/* Device CS delays */
+	of_spi_parse_dt_cs_delay(nc, &spi->cs_setup, "spi-cs-setup-delay-ns");
+	of_spi_parse_dt_cs_delay(nc, &spi->cs_hold, "spi-cs-hold-delay-ns");
+	of_spi_parse_dt_cs_delay(nc, &spi->cs_inactive, "spi-cs-inactive-delay-ns");
+
+	return 0;
+}
+
+static struct spi_device *
+of_register_spi_device(struct spi_controller *ctlr, struct device_node *nc)
+{
+	struct spi_device *spi;
+	int rc;
+
+	/* Alloc an spi_device */
+	spi = spi_alloc_device(ctlr);
+	if (!spi) {
+		dev_err(&ctlr->dev, "spi_device alloc error for %pOF\n", nc);
+		rc = -ENOMEM;
+		goto err_out;
+	}
+
+	/* Select device driver */
+	rc = of_alias_from_compatible(nc, spi->modalias,
+				      sizeof(spi->modalias));
+	if (rc < 0) {
+		dev_err(&ctlr->dev, "cannot find modalias for %pOF\n", nc);
+		goto err_out;
+	}
+
+	rc = of_spi_parse_dt(ctlr, spi, nc);
+	if (rc)
+		goto err_out;
+
+	/* Store a pointer to the node in the device structure */
+	of_node_get(nc);
+
+	device_set_node(&spi->dev, of_fwnode_handle(nc));
+
+	/* Register the new device */
+	rc = spi_add_device(spi);
+	if (rc) {
+		dev_err(&ctlr->dev, "spi_device register error %pOF\n", nc);
+		goto err_of_node_put;
+	}
+
+	return spi;
+
+err_of_node_put:
+	of_node_put(nc);
+err_out:
+	spi_dev_put(spi);
+	return ERR_PTR(rc);
+}
+
+/**
+ * of_register_spi_devices() - Register child devices onto the SPI bus
+ * @ctlr:	Pointer to spi_controller device
+ *
+ * Registers an spi_device for each child node of controller node which
+ * represents a valid SPI slave.
+ */
+static void of_register_spi_devices(struct spi_controller *ctlr)
+{
+	struct spi_device *spi;
+	struct device_node *nc;
+
+	for_each_available_child_of_node(ctlr->dev.of_node, nc) {
+		if (of_node_test_and_set_flag(nc, OF_POPULATED))
+			continue;
+		spi = of_register_spi_device(ctlr, nc);
+		if (IS_ERR(spi)) {
+			dev_warn(&ctlr->dev,
+				 "Failed to create SPI device for %pOF\n", nc);
+			of_node_clear_flag(nc, OF_POPULATED);
+		}
+	}
+}
+#else
+static void of_register_spi_devices(struct spi_controller *ctlr) { }
+#endif
+
+/**
+ * spi_new_ancillary_device() - Register ancillary SPI device
+ * @spi:         Pointer to the main SPI device registering the ancillary device
+ * @chip_select: Chip Select of the ancillary device
+ *
+ * Register an ancillary SPI device; for example some chips have a chip-select
+ * for normal device usage and another one for setup/firmware upload.
+ *
+ * This may only be called from main SPI device's probe routine.
+ *
+ * Return: 0 on success; negative errno on failure
+ */
+struct spi_device *spi_new_ancillary_device(struct spi_device *spi,
+					     u8 chip_select)
+{
+	struct spi_controller *ctlr = spi->controller;
+	struct spi_device *ancillary;
+	int rc = 0;
+
+	/* Alloc an spi_device */
+	ancillary = spi_alloc_device(ctlr);
+	if (!ancillary) {
+		rc = -ENOMEM;
+		goto err_out;
+	}
+
+	strscpy(ancillary->modalias, "dummy", sizeof(ancillary->modalias));
+
+	/* Use provided chip-select for ancillary device */
+	spi_set_chipselect(ancillary, 0, chip_select);
+
+	/* Take over SPI mode/speed from SPI main device */
+	ancillary->max_speed_hz = spi->max_speed_hz;
+	ancillary->mode = spi->mode;
+
+	WARN_ON(!mutex_is_locked(&ctlr->add_lock));
+
+	/* Register the new device */
+	rc = __spi_add_device(ancillary);
+	if (rc) {
+		dev_err(&spi->dev, "failed to register ancillary device\n");
+		goto err_out;
+	}
+
+	return ancillary;
+
+err_out:
+	spi_dev_put(ancillary);
+	return ERR_PTR(rc);
+}
+EXPORT_SYMBOL_GPL(spi_new_ancillary_device);
+
+#ifdef CONFIG_ACPI
+struct acpi_spi_lookup {
+	struct spi_controller 	*ctlr;
+	u32			max_speed_hz;
+	u32			mode;
+	int			irq;
+	u8			bits_per_word;
+	u8			chip_select;
+	int			n;
+	int			index;
+};
+
+static int acpi_spi_count(struct acpi_resource *ares, void *data)
+{
+	struct acpi_resource_spi_serialbus *sb;
+	int *count = data;
+
+	if (ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
+		return 1;
+
+	sb = &ares->data.spi_serial_bus;
+	if (sb->type != ACPI_RESOURCE_SERIAL_TYPE_SPI)
+		return 1;
+
+	*count = *count + 1;
+
+	return 1;
+}
+
+/**
+ * acpi_spi_count_resources - Count the number of SpiSerialBus resources
+ * @adev:	ACPI device
+ *
+ * Return: the number of SpiSerialBus resources in the ACPI-device's
+ * resource-list; or a negative error code.
+ */
+int acpi_spi_count_resources(struct acpi_device *adev)
+{
+	LIST_HEAD(r);
+	int count = 0;
+	int ret;
+
+	ret = acpi_dev_get_resources(adev, &r, acpi_spi_count, &count);
+	if (ret < 0)
+		return ret;
+
+	acpi_dev_free_resource_list(&r);
+
+	return count;
+}
+EXPORT_SYMBOL_GPL(acpi_spi_count_resources);
+
+static void acpi_spi_parse_apple_properties(struct acpi_device *dev,
+					    struct acpi_spi_lookup *lookup)
+{
+	const union acpi_object *obj;
+
+	if (!x86_apple_machine)
+		return;
+
+	if (!acpi_dev_get_property(dev, "spiSclkPeriod", ACPI_TYPE_BUFFER, &obj)
+	    && obj->buffer.length >= 4)
+		lookup->max_speed_hz  = NSEC_PER_SEC / *(u32 *)obj->buffer.pointer;
+
+	if (!acpi_dev_get_property(dev, "spiWordSize", ACPI_TYPE_BUFFER, &obj)
+	    && obj->buffer.length == 8)
+		lookup->bits_per_word = *(u64 *)obj->buffer.pointer;
+
+	if (!acpi_dev_get_property(dev, "spiBitOrder", ACPI_TYPE_BUFFER, &obj)
+	    && obj->buffer.length == 8 && !*(u64 *)obj->buffer.pointer)
+		lookup->mode |= SPI_LSB_FIRST;
+
+	if (!acpi_dev_get_property(dev, "spiSPO", ACPI_TYPE_BUFFER, &obj)
+	    && obj->buffer.length == 8 &&  *(u64 *)obj->buffer.pointer)
+		lookup->mode |= SPI_CPOL;
+
+	if (!acpi_dev_get_property(dev, "spiSPH", ACPI_TYPE_BUFFER, &obj)
+	    && obj->buffer.length == 8 &&  *(u64 *)obj->buffer.pointer)
+		lookup->mode |= SPI_CPHA;
+}
+
+static struct spi_controller *acpi_spi_find_controller_by_adev(struct acpi_device *adev);
+
+static int acpi_spi_add_resource(struct acpi_resource *ares, void *data)
+{
+	struct acpi_spi_lookup *lookup = data;
+	struct spi_controller *ctlr = lookup->ctlr;
+
+	if (ares->type == ACPI_RESOURCE_TYPE_SERIAL_BUS) {
+		struct acpi_resource_spi_serialbus *sb;
+		acpi_handle parent_handle;
+		acpi_status status;
+
+		sb = &ares->data.spi_serial_bus;
+		if (sb->type == ACPI_RESOURCE_SERIAL_TYPE_SPI) {
+
+			if (lookup->index != -1 && lookup->n++ != lookup->index)
+				return 1;
+
+			status = acpi_get_handle(NULL,
+						 sb->resource_source.string_ptr,
+						 &parent_handle);
+
+			if (ACPI_FAILURE(status))
+				return -ENODEV;
+
+			if (ctlr) {
+				if (ACPI_HANDLE(ctlr->dev.parent) != parent_handle)
+					return -ENODEV;
+			} else {
+				struct acpi_device *adev;
+
+				adev = acpi_fetch_acpi_dev(parent_handle);
+				if (!adev)
+					return -ENODEV;
+
+				ctlr = acpi_spi_find_controller_by_adev(adev);
+				if (!ctlr)
+					return -EPROBE_DEFER;
+
+				lookup->ctlr = ctlr;
+			}
+
+			/*
+			 * ACPI DeviceSelection numbering is handled by the
+			 * host controller driver in Windows and can vary
+			 * from driver to driver. In Linux we always expect
+			 * 0 .. max - 1 so we need to ask the driver to
+			 * translate between the two schemes.
+			 */
+			if (ctlr->fw_translate_cs) {
+				int cs = ctlr->fw_translate_cs(ctlr,
+						sb->device_selection);
+				if (cs < 0)
+					return cs;
+				lookup->chip_select = cs;
+			} else {
+				lookup->chip_select = sb->device_selection;
+			}
+
+			lookup->max_speed_hz = sb->connection_speed;
+			lookup->bits_per_word = sb->data_bit_length;
+
+			if (sb->clock_phase == ACPI_SPI_SECOND_PHASE)
+				lookup->mode |= SPI_CPHA;
+			if (sb->clock_polarity == ACPI_SPI_START_HIGH)
+				lookup->mode |= SPI_CPOL;
+			if (sb->device_polarity == ACPI_SPI_ACTIVE_HIGH)
+				lookup->mode |= SPI_CS_HIGH;
+		}
+	} else if (lookup->irq < 0) {
+		struct resource r;
+
+		if (acpi_dev_resource_interrupt(ares, 0, &r))
+			lookup->irq = r.start;
+	}
+
+	/* Always tell the ACPI core to skip this resource */
+	return 1;
+}
+
+/**
+ * acpi_spi_device_alloc - Allocate a spi device, and fill it in with ACPI information
+ * @ctlr: controller to which the spi device belongs
+ * @adev: ACPI Device for the spi device
+ * @index: Index of the spi resource inside the ACPI Node
+ *
+ * This should be used to allocate a new SPI device from and ACPI Device node.
+ * The caller is responsible for calling spi_add_device to register the SPI device.
+ *
+ * If ctlr is set to NULL, the Controller for the SPI device will be looked up
+ * using the resource.
+ * If index is set to -1, index is not used.
+ * Note: If index is -1, ctlr must be set.
+ *
+ * Return: a pointer to the new device, or ERR_PTR on error.
+ */
+struct spi_device *acpi_spi_device_alloc(struct spi_controller *ctlr,
+					 struct acpi_device *adev,
+					 int index)
+{
+	acpi_handle parent_handle = NULL;
+	struct list_head resource_list;
+	struct acpi_spi_lookup lookup = {};
+	struct spi_device *spi;
+	int ret;
+
+	if (!ctlr && index == -1)
+		return ERR_PTR(-EINVAL);
+
+	lookup.ctlr		= ctlr;
+	lookup.irq		= -1;
+	lookup.index		= index;
+	lookup.n		= 0;
+
+	INIT_LIST_HEAD(&resource_list);
+	ret = acpi_dev_get_resources(adev, &resource_list,
+				     acpi_spi_add_resource, &lookup);
+	acpi_dev_free_resource_list(&resource_list);
+
+	if (ret < 0)
+		/* Found SPI in _CRS but it points to another controller */
+		return ERR_PTR(ret);
+
+	if (!lookup.max_speed_hz &&
+	    ACPI_SUCCESS(acpi_get_parent(adev->handle, &parent_handle)) &&
+	    ACPI_HANDLE(lookup.ctlr->dev.parent) == parent_handle) {
+		/* Apple does not use _CRS but nested devices for SPI slaves */
+		acpi_spi_parse_apple_properties(adev, &lookup);
+	}
+
+	if (!lookup.max_speed_hz)
+		return ERR_PTR(-ENODEV);
+
+	spi = spi_alloc_device(lookup.ctlr);
+	if (!spi) {
+		dev_err(&lookup.ctlr->dev, "failed to allocate SPI device for %s\n",
+			dev_name(&adev->dev));
+		return ERR_PTR(-ENOMEM);
+	}
+
+	ACPI_COMPANION_SET(&spi->dev, adev);
+	spi->max_speed_hz	= lookup.max_speed_hz;
+	spi->mode		|= lookup.mode;
+	spi->irq		= lookup.irq;
+	spi->bits_per_word	= lookup.bits_per_word;
+	spi_set_chipselect(spi, 0, lookup.chip_select);
+
+	return spi;
+}
+EXPORT_SYMBOL_GPL(acpi_spi_device_alloc);
+
+static acpi_status acpi_register_spi_device(struct spi_controller *ctlr,
+					    struct acpi_device *adev)
+{
+	struct spi_device *spi;
+
+	if (acpi_bus_get_status(adev) || !adev->status.present ||
+	    acpi_device_enumerated(adev))
+		return AE_OK;
+
+	spi = acpi_spi_device_alloc(ctlr, adev, -1);
+	if (IS_ERR(spi)) {
+		if (PTR_ERR(spi) == -ENOMEM)
+			return AE_NO_MEMORY;
+		else
+			return AE_OK;
+	}
+
+	acpi_set_modalias(adev, acpi_device_hid(adev), spi->modalias,
+			  sizeof(spi->modalias));
+
+	if (spi->irq < 0)
+		spi->irq = acpi_dev_gpio_irq_get(adev, 0);
+
+	acpi_device_set_enumerated(adev);
+
+	adev->power.flags.ignore_parent = true;
+	if (spi_add_device(spi)) {
+		adev->power.flags.ignore_parent = false;
+		dev_err(&ctlr->dev, "failed to add SPI device %s from ACPI\n",
+			dev_name(&adev->dev));
+		spi_dev_put(spi);
+	}
+
+	return AE_OK;
+}
+
+static acpi_status acpi_spi_add_device(acpi_handle handle, u32 level,
+				       void *data, void **return_value)
+{
+	struct acpi_device *adev = acpi_fetch_acpi_dev(handle);
+	struct spi_controller *ctlr = data;
+
+	if (!adev)
+		return AE_OK;
+
+	return acpi_register_spi_device(ctlr, adev);
+}
+
+#define SPI_ACPI_ENUMERATE_MAX_DEPTH		32
+
+static void acpi_register_spi_devices(struct spi_controller *ctlr)
+{
+	acpi_status status;
+	acpi_handle handle;
+
+	handle = ACPI_HANDLE(ctlr->dev.parent);
+	if (!handle)
+		return;
+
+	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
+				     SPI_ACPI_ENUMERATE_MAX_DEPTH,
+				     acpi_spi_add_device, NULL, ctlr, NULL);
+	if (ACPI_FAILURE(status))
+		dev_warn(&ctlr->dev, "failed to enumerate SPI slaves\n");
+}
+#else
+static inline void acpi_register_spi_devices(struct spi_controller *ctlr) {}
+#endif /* CONFIG_ACPI */
+
+static void spi_controller_release(struct device *dev)
+{
+	struct spi_controller *ctlr;
+
+	ctlr = container_of(dev, struct spi_controller, dev);
+	kfree(ctlr);
+}
+
+static struct class spi_master_class = {
+	.name		= "spi_master",
+	.dev_release	= spi_controller_release,
+	.dev_groups	= spi_master_groups,
+};
+
+#ifdef CONFIG_SPI_SLAVE
+/**
+ * spi_slave_abort - abort the ongoing transfer request on an SPI slave
+ *		     controller
+ * @spi: device used for the current transfer
+ */
+int spi_slave_abort(struct spi_device *spi)
+{
+	struct spi_controller *ctlr = spi->controller;
+
+	if (spi_controller_is_slave(ctlr) && ctlr->slave_abort)
+		return ctlr->slave_abort(ctlr);
+
+	return -ENOTSUPP;
+}
+EXPORT_SYMBOL_GPL(spi_slave_abort);
+
+int spi_target_abort(struct spi_device *spi)
+{
+	struct spi_controller *ctlr = spi->controller;
+
+	if (spi_controller_is_target(ctlr) && ctlr->target_abort)
+		return ctlr->target_abort(ctlr);
+
+	return -ENOTSUPP;
+}
+EXPORT_SYMBOL_GPL(spi_target_abort);
+
+static ssize_t slave_show(struct device *dev, struct device_attribute *attr,
+			  char *buf)
+{
+	struct spi_controller *ctlr = container_of(dev, struct spi_controller,
+						   dev);
+	struct device *child;
+
+	child = device_find_any_child(&ctlr->dev);
+	return sysfs_emit(buf, "%s\n", child ? to_spi_device(child)->modalias : NULL);
+}
+
+static ssize_t slave_store(struct device *dev, struct device_attribute *attr,
+			   const char *buf, size_t count)
+{
+	struct spi_controller *ctlr = container_of(dev, struct spi_controller,
+						   dev);
+	struct spi_device *spi;
+	struct device *child;
+	char name[32];
+	int rc;
+
+	rc = sscanf(buf, "%31s", name);
+	if (rc != 1 || !name[0])
+		return -EINVAL;
+
+	child = device_find_any_child(&ctlr->dev);
+	if (child) {
+		/* Remove registered slave */
+		device_unregister(child);
+		put_device(child);
+	}
+
+	if (strcmp(name, "(null)")) {
+		/* Register new slave */
+		spi = spi_alloc_device(ctlr);
+		if (!spi)
+			return -ENOMEM;
+
+		strscpy(spi->modalias, name, sizeof(spi->modalias));
+
+		rc = spi_add_device(spi);
+		if (rc) {
+			spi_dev_put(spi);
+			return rc;
+		}
+	}
+
+	return count;
+}
+
+static DEVICE_ATTR_RW(slave);
+
+static struct attribute *spi_slave_attrs[] = {
+	&dev_attr_slave.attr,
+	NULL,
+};
+
+static const struct attribute_group spi_slave_group = {
+	.attrs = spi_slave_attrs,
+};
+
+static const struct attribute_group *spi_slave_groups[] = {
+	&spi_controller_statistics_group,
+	&spi_slave_group,
+	NULL,
+};
+
+static struct class spi_slave_class = {
+	.name		= "spi_slave",
+	.dev_release	= spi_controller_release,
+	.dev_groups	= spi_slave_groups,
+};
+#else
+extern struct class spi_slave_class;	/* dummy */
+#endif
+
+/**
+ * __spi_alloc_controller - allocate an SPI master or slave controller
+ * @dev: the controller, possibly using the platform_bus
+ * @size: how much zeroed driver-private data to allocate; the pointer to this
+ *	memory is in the driver_data field of the returned device, accessible
+ *	with spi_controller_get_devdata(); the memory is cacheline aligned;
+ *	drivers granting DMA access to portions of their private data need to
+ *	round up @size using ALIGN(size, dma_get_cache_alignment()).
+ * @slave: flag indicating whether to allocate an SPI master (false) or SPI
+ *	slave (true) controller
+ * Context: can sleep
+ *
+ * This call is used only by SPI controller drivers, which are the
+ * only ones directly touching chip registers.  It's how they allocate
+ * an spi_controller structure, prior to calling spi_register_controller().
+ *
+ * This must be called from context that can sleep.
+ *
+ * The caller is responsible for assigning the bus number and initializing the
+ * controller's methods before calling spi_register_controller(); and (after
+ * errors adding the device) calling spi_controller_put() to prevent a memory
+ * leak.
+ *
+ * Return: the SPI controller structure on success, else NULL.
+ */
+struct spi_controller *__spi_alloc_controller(struct device *dev,
+					      unsigned int size, bool slave)
+{
+	struct spi_controller	*ctlr;
+	size_t ctlr_size = ALIGN(sizeof(*ctlr), dma_get_cache_alignment());
+
+	if (!dev)
+		return NULL;
+
+	ctlr = kzalloc(size + ctlr_size, GFP_KERNEL);
+	if (!ctlr)
+		return NULL;
+
+	device_initialize(&ctlr->dev);
+	INIT_LIST_HEAD(&ctlr->queue);
+	spin_lock_init(&ctlr->queue_lock);
+	spin_lock_init(&ctlr->bus_lock_spinlock);
+	mutex_init(&ctlr->bus_lock_mutex);
+	mutex_init(&ctlr->io_mutex);
+	mutex_init(&ctlr->add_lock);
+	ctlr->bus_num = -1;
+	ctlr->num_chipselect = 1;
+	ctlr->slave = slave;
+	if (IS_ENABLED(CONFIG_SPI_SLAVE) && slave)
+		ctlr->dev.class = &spi_slave_class;
+	else
+		ctlr->dev.class = &spi_master_class;
+	ctlr->dev.parent = dev;
+	pm_suspend_ignore_children(&ctlr->dev, true);
+	spi_controller_set_devdata(ctlr, (void *)ctlr + ctlr_size);
+
+	return ctlr;
+}
+EXPORT_SYMBOL_GPL(__spi_alloc_controller);
+
+static void devm_spi_release_controller(struct device *dev, void *ctlr)
+{
+	spi_controller_put(*(struct spi_controller **)ctlr);
+}
+
+/**
+ * __devm_spi_alloc_controller - resource-managed __spi_alloc_controller()
+ * @dev: physical device of SPI controller
+ * @size: how much zeroed driver-private data to allocate
+ * @slave: whether to allocate an SPI master (false) or SPI slave (true)
+ * Context: can sleep
+ *
+ * Allocate an SPI controller and automatically release a reference on it
+ * when @dev is unbound from its driver.  Drivers are thus relieved from
+ * having to call spi_controller_put().
+ *
+ * The arguments to this function are identical to __spi_alloc_controller().
+ *
+ * Return: the SPI controller structure on success, else NULL.
+ */
+struct spi_controller *__devm_spi_alloc_controller(struct device *dev,
+						   unsigned int size,
+						   bool slave)
+{
+	struct spi_controller **ptr, *ctlr;
+
+	ptr = devres_alloc(devm_spi_release_controller, sizeof(*ptr),
+			   GFP_KERNEL);
+	if (!ptr)
+		return NULL;
+
+	ctlr = __spi_alloc_controller(dev, size, slave);
+	if (ctlr) {
+		ctlr->devm_allocated = true;
+		*ptr = ctlr;
+		devres_add(dev, ptr);
+	} else {
+		devres_free(ptr);
+	}
+
+	return ctlr;
+}
+EXPORT_SYMBOL_GPL(__devm_spi_alloc_controller);
+
+/**
+ * spi_get_gpio_descs() - grab chip select GPIOs for the master
+ * @ctlr: The SPI master to grab GPIO descriptors for
+ */
+static int spi_get_gpio_descs(struct spi_controller *ctlr)
+{
+	int nb, i;
+	struct gpio_desc **cs;
+	struct device *dev = &ctlr->dev;
+	unsigned long native_cs_mask = 0;
+	unsigned int num_cs_gpios = 0;
+
+	nb = gpiod_count(dev, "cs");
+	if (nb < 0) {
+		/* No GPIOs at all is fine, else return the error */
+		if (nb == -ENOENT)
+			return 0;
+		return nb;
+	}
+
+	ctlr->num_chipselect = max_t(int, nb, ctlr->num_chipselect);
+
+	cs = devm_kcalloc(dev, ctlr->num_chipselect, sizeof(*cs),
+			  GFP_KERNEL);
+	if (!cs)
+		return -ENOMEM;
+	ctlr->cs_gpiods = cs;
+
+	for (i = 0; i < nb; i++) {
+		/*
+		 * Most chipselects are active low, the inverted
+		 * semantics are handled by special quirks in gpiolib,
+		 * so initializing them GPIOD_OUT_LOW here means
+		 * "unasserted", in most cases this will drive the physical
+		 * line high.
+		 */
+		cs[i] = devm_gpiod_get_index_optional(dev, "cs", i,
+						      GPIOD_OUT_LOW);
+		if (IS_ERR(cs[i]))
+			return PTR_ERR(cs[i]);
+
+		if (cs[i]) {
+			/*
+			 * If we find a CS GPIO, name it after the device and
+			 * chip select line.
+			 */
+			char *gpioname;
+
+			gpioname = devm_kasprintf(dev, GFP_KERNEL, "%s CS%d",
+						  dev_name(dev), i);
+			if (!gpioname)
+				return -ENOMEM;
+			gpiod_set_consumer_name(cs[i], gpioname);
+			num_cs_gpios++;
+			continue;
+		}
+
+		if (ctlr->max_native_cs && i >= ctlr->max_native_cs) {
+			dev_err(dev, "Invalid native chip select %d\n", i);
+			return -EINVAL;
+		}
+		native_cs_mask |= BIT(i);
+	}
+
+	ctlr->unused_native_cs = ffs(~native_cs_mask) - 1;
+
+	if ((ctlr->flags & SPI_CONTROLLER_GPIO_SS) && num_cs_gpios &&
+	    ctlr->max_native_cs && ctlr->unused_native_cs >= ctlr->max_native_cs) {
+		dev_err(dev, "No unused native chip select available\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int spi_controller_check_ops(struct spi_controller *ctlr)
+{
+	/*
+	 * The controller may implement only the high-level SPI-memory like
+	 * operations if it does not support regular SPI transfers, and this is
+	 * valid use case.
+	 * If ->mem_ops or ->mem_ops->exec_op is NULL, we request that at least
+	 * one of the ->transfer_xxx() method be implemented.
+	 */
+	if (!ctlr->mem_ops || !ctlr->mem_ops->exec_op) {
+		if (!ctlr->transfer && !ctlr->transfer_one &&
+		   !ctlr->transfer_one_message) {
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+/* Allocate dynamic bus number using Linux idr */
+static int spi_controller_id_alloc(struct spi_controller *ctlr, int start, int end)
+{
+	int id;
+
+	mutex_lock(&board_lock);
+	id = idr_alloc(&spi_master_idr, ctlr, start, end, GFP_KERNEL);
+	mutex_unlock(&board_lock);
+	if (WARN(id < 0, "couldn't get idr"))
+		return id == -ENOSPC ? -EBUSY : id;
+	ctlr->bus_num = id;
+	return 0;
+}
+
+/**
+ * spi_register_controller - register SPI master or slave controller
+ * @ctlr: initialized master, originally from spi_alloc_master() or
+ *	spi_alloc_slave()
+ * Context: can sleep
+ *
+ * SPI controllers connect to their drivers using some non-SPI bus,
+ * such as the platform bus.  The final stage of probe() in that code
+ * includes calling spi_register_controller() to hook up to this SPI bus glue.
+ *
+ * SPI controllers use board specific (often SOC specific) bus numbers,
+ * and board-specific addressing for SPI devices combines those numbers
+ * with chip select numbers.  Since SPI does not directly support dynamic
+ * device identification, boards need configuration tables telling which
+ * chip is at which address.
+ *
+ * This must be called from context that can sleep.  It returns zero on
+ * success, else a negative error code (dropping the controller's refcount).
+ * After a successful return, the caller is responsible for calling
+ * spi_unregister_controller().
+ *
+ * Return: zero on success, else a negative error code.
+ */
+int spi_register_controller(struct spi_controller *ctlr)
+{
+	struct device		*dev = ctlr->dev.parent;
+	struct boardinfo	*bi;
+	int			first_dynamic;
+	int			status;
+
+	if (!dev)
+		return -ENODEV;
+
+	/*
+	 * Make sure all necessary hooks are implemented before registering
+	 * the SPI controller.
+	 */
+	status = spi_controller_check_ops(ctlr);
+	if (status)
+		return status;
+
+	if (ctlr->bus_num < 0)
+		ctlr->bus_num = of_alias_get_id(ctlr->dev.of_node, "spi");
+	if (ctlr->bus_num >= 0) {
+		/* Devices with a fixed bus num must check-in with the num */
+		status = spi_controller_id_alloc(ctlr, ctlr->bus_num, ctlr->bus_num + 1);
+		if (status)
+			return status;
+	}
+	if (ctlr->bus_num < 0) {
+		first_dynamic = of_alias_get_highest_id("spi");
+		if (first_dynamic < 0)
+			first_dynamic = 0;
+		else
+			first_dynamic++;
+
+		status = spi_controller_id_alloc(ctlr, first_dynamic, 0);
+		if (status)
+			return status;
+	}
+	ctlr->bus_lock_flag = 0;
+	init_completion(&ctlr->xfer_completion);
+	init_completion(&ctlr->cur_msg_completion);
+	if (!ctlr->max_dma_len)
+		ctlr->max_dma_len = INT_MAX;
+
+	/*
+	 * Register the device, then userspace will see it.
+	 * Registration fails if the bus ID is in use.
+	 */
+	dev_set_name(&ctlr->dev, "spi%u", ctlr->bus_num);
+
+	if (!spi_controller_is_slave(ctlr) && ctlr->use_gpio_descriptors) {
+		status = spi_get_gpio_descs(ctlr);
+		if (status)
+			goto free_bus_id;
+		/*
+		 * A controller using GPIO descriptors always
+		 * supports SPI_CS_HIGH if need be.
+		 */
+		ctlr->mode_bits |= SPI_CS_HIGH;
+	}
+
+	/*
+	 * Even if it's just one always-selected device, there must
+	 * be at least one chipselect.
+	 */
+	if (!ctlr->num_chipselect) {
+		status = -EINVAL;
+		goto free_bus_id;
+	}
+
+	/* Setting last_cs to -1 means no chip selected */
+	ctlr->last_cs = -1;
+
+	status = device_add(&ctlr->dev);
+	if (status < 0)
+		goto free_bus_id;
+	dev_dbg(dev, "registered %s %s\n",
+			spi_controller_is_slave(ctlr) ? "slave" : "master",
+			dev_name(&ctlr->dev));
+
+	/*
+	 * If we're using a queued driver, start the queue. Note that we don't
+	 * need the queueing logic if the driver is only supporting high-level
+	 * memory operations.
+	 */
+	if (ctlr->transfer) {
+		dev_info(dev, "controller is unqueued, this is deprecated\n");
+	} else if (ctlr->transfer_one || ctlr->transfer_one_message) {
+		status = spi_controller_initialize_queue(ctlr);
+		if (status) {
+			device_del(&ctlr->dev);
+			goto free_bus_id;
+		}
+	}
+	/* Add statistics */
+	ctlr->pcpu_statistics = spi_alloc_pcpu_stats(dev);
+	if (!ctlr->pcpu_statistics) {
+		dev_err(dev, "Error allocating per-cpu statistics\n");
+		status = -ENOMEM;
+		goto destroy_queue;
+	}
+
+	mutex_lock(&board_lock);
+	list_add_tail(&ctlr->list, &spi_controller_list);
+	list_for_each_entry(bi, &board_list, list)
+		spi_match_controller_to_boardinfo(ctlr, &bi->board_info);
+	mutex_unlock(&board_lock);
+
+	/* Register devices from the device tree and ACPI */
+	of_register_spi_devices(ctlr);
+	acpi_register_spi_devices(ctlr);
+	return status;
+
+destroy_queue:
+	spi_destroy_queue(ctlr);
+free_bus_id:
+	mutex_lock(&board_lock);
+	idr_remove(&spi_master_idr, ctlr->bus_num);
+	mutex_unlock(&board_lock);
+	return status;
+}
+EXPORT_SYMBOL_GPL(spi_register_controller);
+
+static void devm_spi_unregister(struct device *dev, void *res)
+{
+	spi_unregister_controller(*(struct spi_controller **)res);
+}
+
+/**
+ * devm_spi_register_controller - register managed SPI master or slave
+ *	controller
+ * @dev:    device managing SPI controller
+ * @ctlr: initialized controller, originally from spi_alloc_master() or
+ *	spi_alloc_slave()
+ * Context: can sleep
+ *
+ * Register a SPI device as with spi_register_controller() which will
+ * automatically be unregistered and freed.
+ *
+ * Return: zero on success, else a negative error code.
+ */
+int devm_spi_register_controller(struct device *dev,
+				 struct spi_controller *ctlr)
+{
+	struct spi_controller **ptr;
+	int ret;
+
+	ptr = devres_alloc(devm_spi_unregister, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return -ENOMEM;
+
+	ret = spi_register_controller(ctlr);
+	if (!ret) {
+		*ptr = ctlr;
+		devres_add(dev, ptr);
+	} else {
+		devres_free(ptr);
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(devm_spi_register_controller);
+
+static int __unregister(struct device *dev, void *null)
+{
+	spi_unregister_device(to_spi_device(dev));
+	return 0;
+}
+
+/**
+ * spi_unregister_controller - unregister SPI master or slave controller
+ * @ctlr: the controller being unregistered
+ * Context: can sleep
+ *
+ * This call is used only by SPI controller drivers, which are the
+ * only ones directly touching chip registers.
+ *
+ * This must be called from context that can sleep.
+ *
+ * Note that this function also drops a reference to the controller.
+ */
+void spi_unregister_controller(struct spi_controller *ctlr)
+{
+	struct spi_controller *found;
+	int id = ctlr->bus_num;
+
+	/* Prevent addition of new devices, unregister existing ones */
+	if (IS_ENABLED(CONFIG_SPI_DYNAMIC))
+		mutex_lock(&ctlr->add_lock);
+
+	device_for_each_child(&ctlr->dev, NULL, __unregister);
+
+	/* First make sure that this controller was ever added */
+	mutex_lock(&board_lock);
+	found = idr_find(&spi_master_idr, id);
+	mutex_unlock(&board_lock);
+	if (ctlr->queued) {
+		if (spi_destroy_queue(ctlr))
+			dev_err(&ctlr->dev, "queue remove failed\n");
+	}
+	mutex_lock(&board_lock);
+	list_del(&ctlr->list);
+	mutex_unlock(&board_lock);
+
+	device_del(&ctlr->dev);
+
+	/* Free bus id */
+	mutex_lock(&board_lock);
+	if (found == ctlr)
+		idr_remove(&spi_master_idr, id);
+	mutex_unlock(&board_lock);
+
+	if (IS_ENABLED(CONFIG_SPI_DYNAMIC))
+		mutex_unlock(&ctlr->add_lock);
+
+	/*
+	 * Release the last reference on the controller if its driver
+	 * has not yet been converted to devm_spi_alloc_master/slave().
+	 */
+	if (!ctlr->devm_allocated)
+		put_device(&ctlr->dev);
+}
+EXPORT_SYMBOL_GPL(spi_unregister_controller);
+
+static inline int __spi_check_suspended(const struct spi_controller *ctlr)
+{
+	return ctlr->flags & SPI_CONTROLLER_SUSPENDED ? -ESHUTDOWN : 0;
+}
+
+static inline void __spi_mark_suspended(struct spi_controller *ctlr)
+{
+	mutex_lock(&ctlr->bus_lock_mutex);
+	ctlr->flags |= SPI_CONTROLLER_SUSPENDED;
+	mutex_unlock(&ctlr->bus_lock_mutex);
+}
+
+static inline void __spi_mark_resumed(struct spi_controller *ctlr)
+{
+	mutex_lock(&ctlr->bus_lock_mutex);
+	ctlr->flags &= ~SPI_CONTROLLER_SUSPENDED;
+	mutex_unlock(&ctlr->bus_lock_mutex);
+}
+
+int spi_controller_suspend(struct spi_controller *ctlr)
+{
+	int ret = 0;
+
+	/* Basically no-ops for non-queued controllers */
+	if (ctlr->queued) {
+		ret = spi_stop_queue(ctlr);
+		if (ret)
+			dev_err(&ctlr->dev, "queue stop failed\n");
+	}
+
+	__spi_mark_suspended(ctlr);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(spi_controller_suspend);
+
+int spi_controller_resume(struct spi_controller *ctlr)
+{
+	int ret = 0;
+
+	__spi_mark_resumed(ctlr);
+
+	if (ctlr->queued) {
+		ret = spi_start_queue(ctlr);
+		if (ret)
+			dev_err(&ctlr->dev, "queue restart failed\n");
+	}
+	return ret;
+}
+EXPORT_SYMBOL_GPL(spi_controller_resume);
+
+/*-------------------------------------------------------------------------*/
+
+/* Core methods for spi_message alterations */
+
+static void __spi_replace_transfers_release(struct spi_controller *ctlr,
+					    struct spi_message *msg,
+					    void *res)
+{
+	struct spi_replaced_transfers *rxfer = res;
+	size_t i;
+
+	/* Call extra callback if requested */
+	if (rxfer->release)
+		rxfer->release(ctlr, msg, res);
+
+	/* Insert replaced transfers back into the message */
+	list_splice(&rxfer->replaced_transfers, rxfer->replaced_after);
+
+	/* Remove the formerly inserted entries */
+	for (i = 0; i < rxfer->inserted; i++)
+		list_del(&rxfer->inserted_transfers[i].transfer_list);
+}
+
+/**
+ * spi_replace_transfers - replace transfers with several transfers
+ *                         and register change with spi_message.resources
+ * @msg:           the spi_message we work upon
+ * @xfer_first:    the first spi_transfer we want to replace
+ * @remove:        number of transfers to remove
+ * @insert:        the number of transfers we want to insert instead
+ * @release:       extra release code necessary in some circumstances
+ * @extradatasize: extra data to allocate (with alignment guarantees
+ *                 of struct @spi_transfer)
+ * @gfp:           gfp flags
+ *
+ * Returns: pointer to @spi_replaced_transfers,
+ *          PTR_ERR(...) in case of errors.
+ */
+static struct spi_replaced_transfers *spi_replace_transfers(
+	struct spi_message *msg,
+	struct spi_transfer *xfer_first,
+	size_t remove,
+	size_t insert,
+	spi_replaced_release_t release,
+	size_t extradatasize,
+	gfp_t gfp)
+{
+	struct spi_replaced_transfers *rxfer;
+	struct spi_transfer *xfer;
+	size_t i;
+
+	/* Allocate the structure using spi_res */
+	rxfer = spi_res_alloc(msg->spi, __spi_replace_transfers_release,
+			      struct_size(rxfer, inserted_transfers, insert)
+			      + extradatasize,
+			      gfp);
+	if (!rxfer)
+		return ERR_PTR(-ENOMEM);
+
+	/* The release code to invoke before running the generic release */
+	rxfer->release = release;
+
+	/* Assign extradata */
+	if (extradatasize)
+		rxfer->extradata =
+			&rxfer->inserted_transfers[insert];
+
+	/* Init the replaced_transfers list */
+	INIT_LIST_HEAD(&rxfer->replaced_transfers);
+
+	/*
+	 * Assign the list_entry after which we should reinsert
+	 * the @replaced_transfers - it may be spi_message.messages!
+	 */
+	rxfer->replaced_after = xfer_first->transfer_list.prev;
+
+	/* Remove the requested number of transfers */
+	for (i = 0; i < remove; i++) {
+		/*
+		 * If the entry after replaced_after it is msg->transfers
+		 * then we have been requested to remove more transfers
+		 * than are in the list.
+		 */
+		if (rxfer->replaced_after->next == &msg->transfers) {
+			dev_err(&msg->spi->dev,
+				"requested to remove more spi_transfers than are available\n");
+			/* Insert replaced transfers back into the message */
+			list_splice(&rxfer->replaced_transfers,
+				    rxfer->replaced_after);
+
+			/* Free the spi_replace_transfer structure... */
+			spi_res_free(rxfer);
+
+			/* ...and return with an error */
+			return ERR_PTR(-EINVAL);
+		}
+
+		/*
+		 * Remove the entry after replaced_after from list of
+		 * transfers and add it to list of replaced_transfers.
+		 */
+		list_move_tail(rxfer->replaced_after->next,
+			       &rxfer->replaced_transfers);
+	}
+
+	/*
+	 * Create copy of the given xfer with identical settings
+	 * based on the first transfer to get removed.
+	 */
+	for (i = 0; i < insert; i++) {
+		/* We need to run in reverse order */
+		xfer = &rxfer->inserted_transfers[insert - 1 - i];
+
+		/* Copy all spi_transfer data */
+		memcpy(xfer, xfer_first, sizeof(*xfer));
+
+		/* Add to list */
+		list_add(&xfer->transfer_list, rxfer->replaced_after);
+
+		/* Clear cs_change and delay for all but the last */
+		if (i) {
+			xfer->cs_change = false;
+			xfer->delay.value = 0;
+		}
+	}
+
+	/* Set up inserted... */
+	rxfer->inserted = insert;
+
+	/* ...and register it with spi_res/spi_message */
+	spi_res_add(msg, rxfer);
+
+	return rxfer;
+}
+
+static int __spi_split_transfer_maxsize(struct spi_controller *ctlr,
+					struct spi_message *msg,
+					struct spi_transfer **xferp,
+					size_t maxsize,
+					gfp_t gfp)
+{
+	struct spi_transfer *xfer = *xferp, *xfers;
+	struct spi_replaced_transfers *srt;
+	size_t offset;
+	size_t count, i;
+
+	/* Calculate how many we have to replace */
+	count = DIV_ROUND_UP(xfer->len, maxsize);
+
+	/* Create replacement */
+	srt = spi_replace_transfers(msg, xfer, 1, count, NULL, 0, gfp);
+	if (IS_ERR(srt))
+		return PTR_ERR(srt);
+	xfers = srt->inserted_transfers;
+
+	/*
+	 * Now handle each of those newly inserted spi_transfers.
+	 * Note that the replacements spi_transfers all are preset
+	 * to the same values as *xferp, so tx_buf, rx_buf and len
+	 * are all identical (as well as most others)
+	 * so we just have to fix up len and the pointers.
+	 *
+	 * This also includes support for the depreciated
+	 * spi_message.is_dma_mapped interface.
+	 */
+
+	/*
+	 * The first transfer just needs the length modified, so we
+	 * run it outside the loop.
+	 */
+	xfers[0].len = min_t(size_t, maxsize, xfer[0].len);
+
+	/* All the others need rx_buf/tx_buf also set */
+	for (i = 1, offset = maxsize; i < count; offset += maxsize, i++) {
+		/* Update rx_buf, tx_buf and DMA */
+		if (xfers[i].rx_buf)
+			xfers[i].rx_buf += offset;
+		if (xfers[i].rx_dma)
+			xfers[i].rx_dma += offset;
+		if (xfers[i].tx_buf)
+			xfers[i].tx_buf += offset;
+		if (xfers[i].tx_dma)
+			xfers[i].tx_dma += offset;
+
+		/* Update length */
+		xfers[i].len = min(maxsize, xfers[i].len - offset);
+	}
+
+	/*
+	 * We set up xferp to the last entry we have inserted,
+	 * so that we skip those already split transfers.
+	 */
+	*xferp = &xfers[count - 1];
+
+	/* Increment statistics counters */
+	SPI_STATISTICS_INCREMENT_FIELD(ctlr->pcpu_statistics,
+				       transfers_split_maxsize);
+	SPI_STATISTICS_INCREMENT_FIELD(msg->spi->pcpu_statistics,
+				       transfers_split_maxsize);
+
+	return 0;
+}
+
+/**
+ * spi_split_transfers_maxsize - split spi transfers into multiple transfers
+ *                               when an individual transfer exceeds a
+ *                               certain size
+ * @ctlr:    the @spi_controller for this transfer
+ * @msg:   the @spi_message to transform
+ * @maxsize:  the maximum when to apply this
+ * @gfp: GFP allocation flags
+ *
+ * Return: status of transformation
+ */
+int spi_split_transfers_maxsize(struct spi_controller *ctlr,
+				struct spi_message *msg,
+				size_t maxsize,
+				gfp_t gfp)
+{
+	struct spi_transfer *xfer;
+	int ret;
+
+	/*
+	 * Iterate over the transfer_list,
+	 * but note that xfer is advanced to the last transfer inserted
+	 * to avoid checking sizes again unnecessarily (also xfer does
+	 * potentially belong to a different list by the time the
+	 * replacement has happened).
+	 */
+	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+		if (xfer->len > maxsize) {
+			ret = __spi_split_transfer_maxsize(ctlr, msg, &xfer,
+							   maxsize, gfp);
+			if (ret)
+				return ret;
+		}
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(spi_split_transfers_maxsize);
+
+
+/**
+ * spi_split_transfers_maxwords - split SPI transfers into multiple transfers
+ *                                when an individual transfer exceeds a
+ *                                certain number of SPI words
+ * @ctlr:     the @spi_controller for this transfer
+ * @msg:      the @spi_message to transform
+ * @maxwords: the number of words to limit each transfer to
+ * @gfp:      GFP allocation flags
+ *
+ * Return: status of transformation
+ */
+int spi_split_transfers_maxwords(struct spi_controller *ctlr,
+				 struct spi_message *msg,
+				 size_t maxwords,
+				 gfp_t gfp)
+{
+	struct spi_transfer *xfer;
+
+	/*
+	 * Iterate over the transfer_list,
+	 * but note that xfer is advanced to the last transfer inserted
+	 * to avoid checking sizes again unnecessarily (also xfer does
+	 * potentially belong to a different list by the time the
+	 * replacement has happened).
+	 */
+	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+		size_t maxsize;
+		int ret;
+
+		maxsize = maxwords * roundup_pow_of_two(BITS_TO_BYTES(xfer->bits_per_word));
+		if (xfer->len > maxsize) {
+			ret = __spi_split_transfer_maxsize(ctlr, msg, &xfer,
+							   maxsize, gfp);
+			if (ret)
+				return ret;
+		}
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(spi_split_transfers_maxwords);
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * Core methods for SPI controller protocol drivers. Some of the
+ * other core methods are currently defined as inline functions.
+ */
+
+static int __spi_validate_bits_per_word(struct spi_controller *ctlr,
+					u8 bits_per_word)
+{
+	if (ctlr->bits_per_word_mask) {
+		/* Only 32 bits fit in the mask */
+		if (bits_per_word > 32)
+			return -EINVAL;
+		if (!(ctlr->bits_per_word_mask & SPI_BPW_MASK(bits_per_word)))
+			return -EINVAL;
+	}
+
+	return 0;
+}
+
+/**
+ * spi_set_cs_timing - configure CS setup, hold, and inactive delays
+ * @spi: the device that requires specific CS timing configuration
+ *
+ * Return: zero on success, else a negative error code.
+ */
+static int spi_set_cs_timing(struct spi_device *spi)
+{
+	struct device *parent = spi->controller->dev.parent;
+	int status = 0;
+
+	if (spi->controller->set_cs_timing && !spi_get_csgpiod(spi, 0)) {
+		if (spi->controller->auto_runtime_pm) {
+			status = pm_runtime_get_sync(parent);
+			if (status < 0) {
+				pm_runtime_put_noidle(parent);
+				dev_err(&spi->controller->dev, "Failed to power device: %d\n",
+					status);
+				return status;
+			}
+
+			status = spi->controller->set_cs_timing(spi);
+			pm_runtime_mark_last_busy(parent);
+			pm_runtime_put_autosuspend(parent);
+		} else {
+			status = spi->controller->set_cs_timing(spi);
+		}
+	}
+	return status;
+}
+
+/**
+ * spi_setup - setup SPI mode and clock rate
+ * @spi: the device whose settings are being modified
+ * Context: can sleep, and no requests are queued to the device
+ *
+ * SPI protocol drivers may need to update the transfer mode if the
+ * device doesn't work with its default.  They may likewise need
+ * to update clock rates or word sizes from initial values.  This function
+ * changes those settings, and must be called from a context that can sleep.
+ * Except for SPI_CS_HIGH, which takes effect immediately, the changes take
+ * effect the next time the device is selected and data is transferred to
+ * or from it.  When this function returns, the SPI device is deselected.
+ *
+ * Note that this call will fail if the protocol driver specifies an option
+ * that the underlying controller or its driver does not support.  For
+ * example, not all hardware supports wire transfers using nine bit words,
+ * LSB-first wire encoding, or active-high chipselects.
+ *
+ * Return: zero on success, else a negative error code.
+ */
+int spi_setup(struct spi_device *spi)
+{
+	unsigned	bad_bits, ugly_bits;
+	int		status = 0;
+
+	/*
+	 * Check mode to prevent that any two of DUAL, QUAD and NO_MOSI/MISO
+	 * are set at the same time.
+	 */
+	if ((hweight_long(spi->mode &
+		(SPI_TX_DUAL | SPI_TX_QUAD | SPI_NO_TX)) > 1) ||
+	    (hweight_long(spi->mode &
+		(SPI_RX_DUAL | SPI_RX_QUAD | SPI_NO_RX)) > 1)) {
+		dev_err(&spi->dev,
+		"setup: can not select any two of dual, quad and no-rx/tx at the same time\n");
+		return -EINVAL;
+	}
+	/* If it is SPI_3WIRE mode, DUAL and QUAD should be forbidden */
+	if ((spi->mode & SPI_3WIRE) && (spi->mode &
+		(SPI_TX_DUAL | SPI_TX_QUAD | SPI_TX_OCTAL |
+		 SPI_RX_DUAL | SPI_RX_QUAD | SPI_RX_OCTAL)))
+		return -EINVAL;
+	/*
+	 * Help drivers fail *cleanly* when they need options
+	 * that aren't supported with their current controller.
+	 * SPI_CS_WORD has a fallback software implementation,
+	 * so it is ignored here.
+	 */
+	bad_bits = spi->mode & ~(spi->controller->mode_bits | SPI_CS_WORD |
+				 SPI_NO_TX | SPI_NO_RX);
+	ugly_bits = bad_bits &
+		    (SPI_TX_DUAL | SPI_TX_QUAD | SPI_TX_OCTAL |
+		     SPI_RX_DUAL | SPI_RX_QUAD | SPI_RX_OCTAL);
+	if (ugly_bits) {
+		dev_warn(&spi->dev,
+			 "setup: ignoring unsupported mode bits %x\n",
+			 ugly_bits);
+		spi->mode &= ~ugly_bits;
+		bad_bits &= ~ugly_bits;
+	}
+	if (bad_bits) {
+		dev_err(&spi->dev, "setup: unsupported mode bits %x\n",
+			bad_bits);
+		return -EINVAL;
+	}
+
+	if (!spi->bits_per_word) {
+		spi->bits_per_word = 8;
+	} else {
+		/*
+		 * Some controllers may not support the default 8 bits-per-word
+		 * so only perform the check when this is explicitly provided.
+		 */
+		status = __spi_validate_bits_per_word(spi->controller,
+						      spi->bits_per_word);
+		if (status)
+			return status;
+	}
+
+	if (spi->controller->max_speed_hz &&
+	    (!spi->max_speed_hz ||
+	     spi->max_speed_hz > spi->controller->max_speed_hz))
+		spi->max_speed_hz = spi->controller->max_speed_hz;
+
+	mutex_lock(&spi->controller->io_mutex);
+
+	if (spi->controller->setup) {
+		status = spi->controller->setup(spi);
+		if (status) {
+			mutex_unlock(&spi->controller->io_mutex);
+			dev_err(&spi->controller->dev, "Failed to setup device: %d\n",
+				status);
+			return status;
+		}
+	}
+
+	status = spi_set_cs_timing(spi);
+	if (status) {
+		mutex_unlock(&spi->controller->io_mutex);
+		return status;
+	}
+
+	if (spi->controller->auto_runtime_pm && spi->controller->set_cs) {
+		status = pm_runtime_resume_and_get(spi->controller->dev.parent);
+		if (status < 0) {
+			mutex_unlock(&spi->controller->io_mutex);
+			dev_err(&spi->controller->dev, "Failed to power device: %d\n",
+				status);
+			return status;
+		}
+
+		/*
+		 * We do not want to return positive value from pm_runtime_get,
+		 * there are many instances of devices calling spi_setup() and
+		 * checking for a non-zero return value instead of a negative
+		 * return value.
+		 */
+		status = 0;
+
+		spi_set_cs(spi, false, true);
+		pm_runtime_mark_last_busy(spi->controller->dev.parent);
+		pm_runtime_put_autosuspend(spi->controller->dev.parent);
+	} else {
+		spi_set_cs(spi, false, true);
+	}
+
+	mutex_unlock(&spi->controller->io_mutex);
+
+	if (spi->rt && !spi->controller->rt) {
+		spi->controller->rt = true;
+		spi_set_thread_rt(spi->controller);
+	}
+
+	trace_spi_setup(spi, status);
+
+	dev_dbg(&spi->dev, "setup mode %lu, %s%s%s%s%u bits/w, %u Hz max --> %d\n",
+			spi->mode & SPI_MODE_X_MASK,
+			(spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
+			(spi->mode & SPI_LSB_FIRST) ? "lsb, " : "",
+			(spi->mode & SPI_3WIRE) ? "3wire, " : "",
+			(spi->mode & SPI_LOOP) ? "loopback, " : "",
+			spi->bits_per_word, spi->max_speed_hz,
+			status);
+
+	return status;
+}
+EXPORT_SYMBOL_GPL(spi_setup);
+
+static int _spi_xfer_word_delay_update(struct spi_transfer *xfer,
+				       struct spi_device *spi)
+{
+	int delay1, delay2;
+
+	delay1 = spi_delay_to_ns(&xfer->word_delay, xfer);
+	if (delay1 < 0)
+		return delay1;
+
+	delay2 = spi_delay_to_ns(&spi->word_delay, xfer);
+	if (delay2 < 0)
+		return delay2;
+
+	if (delay1 < delay2)
+		memcpy(&xfer->word_delay, &spi->word_delay,
+		       sizeof(xfer->word_delay));
+
+	return 0;
+}
+
+static int __spi_validate(struct spi_device *spi, struct spi_message *message)
+{
+	struct spi_controller *ctlr = spi->controller;
+	struct spi_transfer *xfer;
+	int w_size;
+
+	if (list_empty(&message->transfers))
+		return -EINVAL;
+
+	/*
+	 * If an SPI controller does not support toggling the CS line on each
+	 * transfer (indicated by the SPI_CS_WORD flag) or we are using a GPIO
+	 * for the CS line, we can emulate the CS-per-word hardware function by
+	 * splitting transfers into one-word transfers and ensuring that
+	 * cs_change is set for each transfer.
+	 */
+	if ((spi->mode & SPI_CS_WORD) && (!(ctlr->mode_bits & SPI_CS_WORD) ||
+					  spi_get_csgpiod(spi, 0))) {
+		size_t maxsize = BITS_TO_BYTES(spi->bits_per_word);
+		int ret;
+
+		/* spi_split_transfers_maxsize() requires message->spi */
+		message->spi = spi;
+
+		ret = spi_split_transfers_maxsize(ctlr, message, maxsize,
+						  GFP_KERNEL);
+		if (ret)
+			return ret;
+
+		list_for_each_entry(xfer, &message->transfers, transfer_list) {
+			/* Don't change cs_change on the last entry in the list */
+			if (list_is_last(&xfer->transfer_list, &message->transfers))
+				break;
+			xfer->cs_change = 1;
+		}
+	}
+
+	/*
+	 * Half-duplex links include original MicroWire, and ones with
+	 * only one data pin like SPI_3WIRE (switches direction) or where
+	 * either MOSI or MISO is missing.  They can also be caused by
+	 * software limitations.
+	 */
+	if ((ctlr->flags & SPI_CONTROLLER_HALF_DUPLEX) ||
+	    (spi->mode & SPI_3WIRE)) {
+		unsigned flags = ctlr->flags;
+
+		list_for_each_entry(xfer, &message->transfers, transfer_list) {
+			if (xfer->rx_buf && xfer->tx_buf)
+				return -EINVAL;
+			if ((flags & SPI_CONTROLLER_NO_TX) && xfer->tx_buf)
+				return -EINVAL;
+			if ((flags & SPI_CONTROLLER_NO_RX) && xfer->rx_buf)
+				return -EINVAL;
+		}
+	}
+
+	/*
+	 * Set transfer bits_per_word and max speed as spi device default if
+	 * it is not set for this transfer.
+	 * Set transfer tx_nbits and rx_nbits as single transfer default
+	 * (SPI_NBITS_SINGLE) if it is not set for this transfer.
+	 * Ensure transfer word_delay is at least as long as that required by
+	 * device itself.
+	 */
+	message->frame_length = 0;
+	list_for_each_entry(xfer, &message->transfers, transfer_list) {
+		xfer->effective_speed_hz = 0;
+		message->frame_length += xfer->len;
+		if (!xfer->bits_per_word)
+			xfer->bits_per_word = spi->bits_per_word;
+
+		if (!xfer->speed_hz)
+			xfer->speed_hz = spi->max_speed_hz;
+
+		if (ctlr->max_speed_hz && xfer->speed_hz > ctlr->max_speed_hz)
+			xfer->speed_hz = ctlr->max_speed_hz;
+
+		if (__spi_validate_bits_per_word(ctlr, xfer->bits_per_word))
+			return -EINVAL;
+
+		/*
+		 * SPI transfer length should be multiple of SPI word size
+		 * where SPI word size should be power-of-two multiple.
+		 */
+		if (xfer->bits_per_word <= 8)
+			w_size = 1;
+		else if (xfer->bits_per_word <= 16)
+			w_size = 2;
+		else
+			w_size = 4;
+
+		/* No partial transfers accepted */
+		if (xfer->len % w_size)
+			return -EINVAL;
+
+		if (xfer->speed_hz && ctlr->min_speed_hz &&
+		    xfer->speed_hz < ctlr->min_speed_hz)
+			return -EINVAL;
+
+		if (xfer->tx_buf && !xfer->tx_nbits)
+			xfer->tx_nbits = SPI_NBITS_SINGLE;
+		if (xfer->rx_buf && !xfer->rx_nbits)
+			xfer->rx_nbits = SPI_NBITS_SINGLE;
+		/*
+		 * Check transfer tx/rx_nbits:
+		 * 1. check the value matches one of single, dual and quad
+		 * 2. check tx/rx_nbits match the mode in spi_device
+		 */
+		if (xfer->tx_buf) {
+			if (spi->mode & SPI_NO_TX)
+				return -EINVAL;
+			if (xfer->tx_nbits != SPI_NBITS_SINGLE &&
+				xfer->tx_nbits != SPI_NBITS_DUAL &&
+				xfer->tx_nbits != SPI_NBITS_QUAD)
+				return -EINVAL;
+			if ((xfer->tx_nbits == SPI_NBITS_DUAL) &&
+				!(spi->mode & (SPI_TX_DUAL | SPI_TX_QUAD)))
+				return -EINVAL;
+			if ((xfer->tx_nbits == SPI_NBITS_QUAD) &&
+				!(spi->mode & SPI_TX_QUAD))
+				return -EINVAL;
+		}
+		/* Check transfer rx_nbits */
+		if (xfer->rx_buf) {
+			if (spi->mode & SPI_NO_RX)
+				return -EINVAL;
+			if (xfer->rx_nbits != SPI_NBITS_SINGLE &&
+				xfer->rx_nbits != SPI_NBITS_DUAL &&
+				xfer->rx_nbits != SPI_NBITS_QUAD)
+				return -EINVAL;
+			if ((xfer->rx_nbits == SPI_NBITS_DUAL) &&
+				!(spi->mode & (SPI_RX_DUAL | SPI_RX_QUAD)))
+				return -EINVAL;
+			if ((xfer->rx_nbits == SPI_NBITS_QUAD) &&
+				!(spi->mode & SPI_RX_QUAD))
+				return -EINVAL;
+		}
+
+		if (_spi_xfer_word_delay_update(xfer, spi))
+			return -EINVAL;
+	}
+
+	message->status = -EINPROGRESS;
+
+	return 0;
+}
+
+static int __spi_async(struct spi_device *spi, struct spi_message *message)
+{
+	struct spi_controller *ctlr = spi->controller;
+	struct spi_transfer *xfer;
+
+	/*
+	 * Some controllers do not support doing regular SPI transfers. Return
+	 * ENOTSUPP when this is the case.
+	 */
+	if (!ctlr->transfer)
+		return -ENOTSUPP;
+
+	message->spi = spi;
+
+	SPI_STATISTICS_INCREMENT_FIELD(ctlr->pcpu_statistics, spi_async);
+	SPI_STATISTICS_INCREMENT_FIELD(spi->pcpu_statistics, spi_async);
+
+	trace_spi_message_submit(message);
+
+	if (!ctlr->ptp_sts_supported) {
+		list_for_each_entry(xfer, &message->transfers, transfer_list) {
+			xfer->ptp_sts_word_pre = 0;
+			ptp_read_system_prets(xfer->ptp_sts);
+		}
+	}
+
+	return ctlr->transfer(spi, message);
+}
+
+/**
+ * spi_async - asynchronous SPI transfer
+ * @spi: device with which data will be exchanged
+ * @message: describes the data transfers, including completion callback
+ * Context: any (IRQs may be blocked, etc)
+ *
+ * This call may be used in_irq and other contexts which can't sleep,
+ * as well as from task contexts which can sleep.
+ *
+ * The completion callback is invoked in a context which can't sleep.
+ * Before that invocation, the value of message->status is undefined.
+ * When the callback is issued, message->status holds either zero (to
+ * indicate complete success) or a negative error code.  After that
+ * callback returns, the driver which issued the transfer request may
+ * deallocate the associated memory; it's no longer in use by any SPI
+ * core or controller driver code.
+ *
+ * Note that although all messages to a spi_device are handled in
+ * FIFO order, messages may go to different devices in other orders.
+ * Some device might be higher priority, or have various "hard" access
+ * time requirements, for example.
+ *
+ * On detection of any fault during the transfer, processing of
+ * the entire message is aborted, and the device is deselected.
+ * Until returning from the associated message completion callback,
+ * no other spi_message queued to that device will be processed.
+ * (This rule applies equally to all the synchronous transfer calls,
+ * which are wrappers around this core asynchronous primitive.)
+ *
+ * Return: zero on success, else a negative error code.
+ */
+int spi_async(struct spi_device *spi, struct spi_message *message)
+{
+	struct spi_controller *ctlr = spi->controller;
+	int ret;
+	unsigned long flags;
+
+	ret = __spi_validate(spi, message);
+	if (ret != 0)
+		return ret;
+
+	spin_lock_irqsave(&ctlr->bus_lock_spinlock, flags);
+
+	if (ctlr->bus_lock_flag)
+		ret = -EBUSY;
+	else
+		ret = __spi_async(spi, message);
+
+	spin_unlock_irqrestore(&ctlr->bus_lock_spinlock, flags);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(spi_async);
+
+/**
+ * spi_async_locked - version of spi_async with exclusive bus usage
+ * @spi: device with which data will be exchanged
+ * @message: describes the data transfers, including completion callback
+ * Context: any (IRQs may be blocked, etc)
+ *
+ * This call may be used in_irq and other contexts which can't sleep,
+ * as well as from task contexts which can sleep.
+ *
+ * The completion callback is invoked in a context which can't sleep.
+ * Before that invocation, the value of message->status is undefined.
+ * When the callback is issued, message->status holds either zero (to
+ * indicate complete success) or a negative error code.  After that
+ * callback returns, the driver which issued the transfer request may
+ * deallocate the associated memory; it's no longer in use by any SPI
+ * core or controller driver code.
+ *
+ * Note that although all messages to a spi_device are handled in
+ * FIFO order, messages may go to different devices in other orders.
+ * Some device might be higher priority, or have various "hard" access
+ * time requirements, for example.
+ *
+ * On detection of any fault during the transfer, processing of
+ * the entire message is aborted, and the device is deselected.
+ * Until returning from the associated message completion callback,
+ * no other spi_message queued to that device will be processed.
+ * (This rule applies equally to all the synchronous transfer calls,
+ * which are wrappers around this core asynchronous primitive.)
+ *
+ * Return: zero on success, else a negative error code.
+ */
+static int spi_async_locked(struct spi_device *spi, struct spi_message *message)
+{
+	struct spi_controller *ctlr = spi->controller;
+	int ret;
+	unsigned long flags;
+
+	ret = __spi_validate(spi, message);
+	if (ret != 0)
+		return ret;
+
+	spin_lock_irqsave(&ctlr->bus_lock_spinlock, flags);
+
+	ret = __spi_async(spi, message);
+
+	spin_unlock_irqrestore(&ctlr->bus_lock_spinlock, flags);
+
+	return ret;
+
+}
+
+static void __spi_transfer_message_noqueue(struct spi_controller *ctlr, struct spi_message *msg)
+{
+	bool was_busy;
+	int ret;
+
+	mutex_lock(&ctlr->io_mutex);
+
+	was_busy = ctlr->busy;
+
+	ctlr->cur_msg = msg;
+	ret = __spi_pump_transfer_message(ctlr, msg, was_busy);
+	if (ret)
+		dev_err(&ctlr->dev, "noqueue transfer failed\n");
+	ctlr->cur_msg = NULL;
+	ctlr->fallback = false;
+
+	if (!was_busy) {
+		kfree(ctlr->dummy_rx);
+		ctlr->dummy_rx = NULL;
+		kfree(ctlr->dummy_tx);
+		ctlr->dummy_tx = NULL;
+		if (ctlr->unprepare_transfer_hardware &&
+		    ctlr->unprepare_transfer_hardware(ctlr))
+			dev_err(&ctlr->dev,
+				"failed to unprepare transfer hardware\n");
+		spi_idle_runtime_pm(ctlr);
+	}
+
+	mutex_unlock(&ctlr->io_mutex);
+}
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * Utility methods for SPI protocol drivers, layered on
+ * top of the core.  Some other utility methods are defined as
+ * inline functions.
+ */
+
+static void spi_complete(void *arg)
+{
+	complete(arg);
+}
+
+static int __spi_sync(struct spi_device *spi, struct spi_message *message)
+{
+	DECLARE_COMPLETION_ONSTACK(done);
+	int status;
+	struct spi_controller *ctlr = spi->controller;
+
+	if (__spi_check_suspended(ctlr)) {
+		dev_warn_once(&spi->dev, "Attempted to sync while suspend\n");
+		return -ESHUTDOWN;
+	}
+
+	status = __spi_validate(spi, message);
+	if (status != 0)
+		return status;
+
+	message->spi = spi;
+
+	SPI_STATISTICS_INCREMENT_FIELD(ctlr->pcpu_statistics, spi_sync);
+	SPI_STATISTICS_INCREMENT_FIELD(spi->pcpu_statistics, spi_sync);
+
+	/*
+	 * Checking queue_empty here only guarantees async/sync message
+	 * ordering when coming from the same context. It does not need to
+	 * guard against reentrancy from a different context. The io_mutex
+	 * will catch those cases.
+	 */
+	if (READ_ONCE(ctlr->queue_empty) && !ctlr->must_async) {
+		message->actual_length = 0;
+		message->status = -EINPROGRESS;
+
+		trace_spi_message_submit(message);
+
+		SPI_STATISTICS_INCREMENT_FIELD(ctlr->pcpu_statistics, spi_sync_immediate);
+		SPI_STATISTICS_INCREMENT_FIELD(spi->pcpu_statistics, spi_sync_immediate);
+
+		__spi_transfer_message_noqueue(ctlr, message);
+
+		return message->status;
+	}
+
+	/*
+	 * There are messages in the async queue that could have originated
+	 * from the same context, so we need to preserve ordering.
+	 * Therefor we send the message to the async queue and wait until they
+	 * are completed.
+	 */
+	message->complete = spi_complete;
+	message->context = &done;
+	status = spi_async_locked(spi, message);
+	if (status == 0) {
+		wait_for_completion(&done);
+		status = message->status;
+	}
+	message->context = NULL;
+
+	return status;
+}
+
+/**
+ * spi_sync - blocking/synchronous SPI data transfers
+ * @spi: device with which data will be exchanged
+ * @message: describes the data transfers
+ * Context: can sleep
+ *
+ * This call may only be used from a context that may sleep.  The sleep
+ * is non-interruptible, and has no timeout.  Low-overhead controller
+ * drivers may DMA directly into and out of the message buffers.
+ *
+ * Note that the SPI device's chip select is active during the message,
+ * and then is normally disabled between messages.  Drivers for some
+ * frequently-used devices may want to minimize costs of selecting a chip,
+ * by leaving it selected in anticipation that the next message will go
+ * to the same chip.  (That may increase power usage.)
+ *
+ * Also, the caller is guaranteeing that the memory associated with the
+ * message will not be freed before this call returns.
+ *
+ * Return: zero on success, else a negative error code.
+ */
+int spi_sync(struct spi_device *spi, struct spi_message *message)
+{
+	int ret;
+
+	mutex_lock(&spi->controller->bus_lock_mutex);
+	ret = __spi_sync(spi, message);
+	mutex_unlock(&spi->controller->bus_lock_mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(spi_sync);
+
+/**
+ * spi_sync_locked - version of spi_sync with exclusive bus usage
+ * @spi: device with which data will be exchanged
+ * @message: describes the data transfers
+ * Context: can sleep
+ *
+ * This call may only be used from a context that may sleep.  The sleep
+ * is non-interruptible, and has no timeout.  Low-overhead controller
+ * drivers may DMA directly into and out of the message buffers.
+ *
+ * This call should be used by drivers that require exclusive access to the
+ * SPI bus. It has to be preceded by a spi_bus_lock call. The SPI bus must
+ * be released by a spi_bus_unlock call when the exclusive access is over.
+ *
+ * Return: zero on success, else a negative error code.
+ */
+int spi_sync_locked(struct spi_device *spi, struct spi_message *message)
+{
+	return __spi_sync(spi, message);
+}
+EXPORT_SYMBOL_GPL(spi_sync_locked);
+
+/**
+ * spi_bus_lock - obtain a lock for exclusive SPI bus usage
+ * @ctlr: SPI bus master that should be locked for exclusive bus access
+ * Context: can sleep
+ *
+ * This call may only be used from a context that may sleep.  The sleep
+ * is non-interruptible, and has no timeout.
+ *
+ * This call should be used by drivers that require exclusive access to the
+ * SPI bus. The SPI bus must be released by a spi_bus_unlock call when the
+ * exclusive access is over. Data transfer must be done by spi_sync_locked
+ * and spi_async_locked calls when the SPI bus lock is held.
+ *
+ * Return: always zero.
+ */
+int spi_bus_lock(struct spi_controller *ctlr)
+{
+	unsigned long flags;
+
+	mutex_lock(&ctlr->bus_lock_mutex);
+
+	spin_lock_irqsave(&ctlr->bus_lock_spinlock, flags);
+	ctlr->bus_lock_flag = 1;
+	spin_unlock_irqrestore(&ctlr->bus_lock_spinlock, flags);
+
+	/* Mutex remains locked until spi_bus_unlock() is called */
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(spi_bus_lock);
+
+/**
+ * spi_bus_unlock - release the lock for exclusive SPI bus usage
+ * @ctlr: SPI bus master that was locked for exclusive bus access
+ * Context: can sleep
+ *
+ * This call may only be used from a context that may sleep.  The sleep
+ * is non-interruptible, and has no timeout.
+ *
+ * This call releases an SPI bus lock previously obtained by an spi_bus_lock
+ * call.
+ *
+ * Return: always zero.
+ */
+int spi_bus_unlock(struct spi_controller *ctlr)
+{
+	ctlr->bus_lock_flag = 0;
+
+	mutex_unlock(&ctlr->bus_lock_mutex);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(spi_bus_unlock);
+
+/* Portable code must never pass more than 32 bytes */
+#define	SPI_BUFSIZ	max(32, SMP_CACHE_BYTES)
+
+static u8	*buf;
+
+/**
+ * spi_write_then_read - SPI synchronous write followed by read
+ * @spi: device with which data will be exchanged
+ * @txbuf: data to be written (need not be DMA-safe)
+ * @n_tx: size of txbuf, in bytes
+ * @rxbuf: buffer into which data will be read (need not be DMA-safe)
+ * @n_rx: size of rxbuf, in bytes
+ * Context: can sleep
+ *
+ * This performs a half duplex MicroWire style transaction with the
+ * device, sending txbuf and then reading rxbuf.  The return value
+ * is zero for success, else a negative errno status code.
+ * This call may only be used from a context that may sleep.
+ *
+ * Parameters to this routine are always copied using a small buffer.
+ * Performance-sensitive or bulk transfer code should instead use
+ * spi_{async,sync}() calls with DMA-safe buffers.
+ *
+ * Return: zero on success, else a negative error code.
+ */
+int spi_write_then_read(struct spi_device *spi,
+		const void *txbuf, unsigned n_tx,
+		void *rxbuf, unsigned n_rx)
+{
+	static DEFINE_MUTEX(lock);
+
+	int			status;
+	struct spi_message	message;
+	struct spi_transfer	x[2];
+	u8			*local_buf;
+
+	/*
+	 * Use preallocated DMA-safe buffer if we can. We can't avoid
+	 * copying here, (as a pure convenience thing), but we can
+	 * keep heap costs out of the hot path unless someone else is
+	 * using the pre-allocated buffer or the transfer is too large.
+	 */
+	if ((n_tx + n_rx) > SPI_BUFSIZ || !mutex_trylock(&lock)) {
+		local_buf = kmalloc(max((unsigned)SPI_BUFSIZ, n_tx + n_rx),
+				    GFP_KERNEL | GFP_DMA);
+		if (!local_buf)
+			return -ENOMEM;
+	} else {
+		local_buf = buf;
+	}
+
+	spi_message_init(&message);
+	memset(x, 0, sizeof(x));
+	if (n_tx) {
+		x[0].len = n_tx;
+		spi_message_add_tail(&x[0], &message);
+	}
+	if (n_rx) {
+		x[1].len = n_rx;
+		spi_message_add_tail(&x[1], &message);
+	}
+
+	memcpy(local_buf, txbuf, n_tx);
+	x[0].tx_buf = local_buf;
+	x[1].rx_buf = local_buf + n_tx;
+
+	/* Do the I/O */
+	status = spi_sync(spi, &message);
+	if (status == 0)
+		memcpy(rxbuf, x[1].rx_buf, n_rx);
+
+	if (x[0].tx_buf == buf)
+		mutex_unlock(&lock);
+	else
+		kfree(local_buf);
+
+	return status;
+}
+EXPORT_SYMBOL_GPL(spi_write_then_read);
+
+/*-------------------------------------------------------------------------*/
+
+#if IS_ENABLED(CONFIG_OF_DYNAMIC)
+/* Must call put_device() when done with returned spi_device device */
+static struct spi_device *of_find_spi_device_by_node(struct device_node *node)
+{
+	struct device *dev = bus_find_device_by_of_node(&spi_bus_type, node);
+
+	return dev ? to_spi_device(dev) : NULL;
+}
+
+/* The spi controllers are not using spi_bus, so we find it with another way */
+static struct spi_controller *of_find_spi_controller_by_node(struct device_node *node)
+{
+	struct device *dev;
+
+	dev = class_find_device_by_of_node(&spi_master_class, node);
+	if (!dev && IS_ENABLED(CONFIG_SPI_SLAVE))
+		dev = class_find_device_by_of_node(&spi_slave_class, node);
+	if (!dev)
+		return NULL;
+
+	/* Reference got in class_find_device */
+	return container_of(dev, struct spi_controller, dev);
+}
+
+static int of_spi_notify(struct notifier_block *nb, unsigned long action,
+			 void *arg)
+{
+	struct of_reconfig_data *rd = arg;
+	struct spi_controller *ctlr;
+	struct spi_device *spi;
+
+	switch (of_reconfig_get_state_change(action, arg)) {
+	case OF_RECONFIG_CHANGE_ADD:
+		ctlr = of_find_spi_controller_by_node(rd->dn->parent);
+		if (ctlr == NULL)
+			return NOTIFY_OK;	/* Not for us */
+
+		if (of_node_test_and_set_flag(rd->dn, OF_POPULATED)) {
+			put_device(&ctlr->dev);
+			return NOTIFY_OK;
+		}
+
+		/*
+		 * Clear the flag before adding the device so that fw_devlink
+		 * doesn't skip adding consumers to this device.
+		 */
+		rd->dn->fwnode.flags &= ~FWNODE_FLAG_NOT_DEVICE;
+		spi = of_register_spi_device(ctlr, rd->dn);
+		put_device(&ctlr->dev);
+
+		if (IS_ERR(spi)) {
+			pr_err("%s: failed to create for '%pOF'\n",
+					__func__, rd->dn);
+			of_node_clear_flag(rd->dn, OF_POPULATED);
+			return notifier_from_errno(PTR_ERR(spi));
+		}
+		break;
+
+	case OF_RECONFIG_CHANGE_REMOVE:
+		/* Already depopulated? */
+		if (!of_node_check_flag(rd->dn, OF_POPULATED))
+			return NOTIFY_OK;
+
+		/* Find our device by node */
+		spi = of_find_spi_device_by_node(rd->dn);
+		if (spi == NULL)
+			return NOTIFY_OK;	/* No? not meant for us */
+
+		/* Unregister takes one ref away */
+		spi_unregister_device(spi);
+
+		/* And put the reference of the find */
+		put_device(&spi->dev);
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block spi_of_notifier = {
+	.notifier_call = of_spi_notify,
+};
+#else /* IS_ENABLED(CONFIG_OF_DYNAMIC) */
+extern struct notifier_block spi_of_notifier;
+#endif /* IS_ENABLED(CONFIG_OF_DYNAMIC) */
+
+#if IS_ENABLED(CONFIG_ACPI)
+static int spi_acpi_controller_match(struct device *dev, const void *data)
+{
+	return ACPI_COMPANION(dev->parent) == data;
+}
+
+static struct spi_controller *acpi_spi_find_controller_by_adev(struct acpi_device *adev)
+{
+	struct device *dev;
+
+	dev = class_find_device(&spi_master_class, NULL, adev,
+				spi_acpi_controller_match);
+	if (!dev && IS_ENABLED(CONFIG_SPI_SLAVE))
+		dev = class_find_device(&spi_slave_class, NULL, adev,
+					spi_acpi_controller_match);
+	if (!dev)
+		return NULL;
+
+	return container_of(dev, struct spi_controller, dev);
+}
+
+static struct spi_device *acpi_spi_find_device_by_adev(struct acpi_device *adev)
+{
+	struct device *dev;
+
+	dev = bus_find_device_by_acpi_dev(&spi_bus_type, adev);
+	return to_spi_device(dev);
+}
+
+static int acpi_spi_notify(struct notifier_block *nb, unsigned long value,
+			   void *arg)
+{
+	struct acpi_device *adev = arg;
+	struct spi_controller *ctlr;
+	struct spi_device *spi;
+
+	switch (value) {
+	case ACPI_RECONFIG_DEVICE_ADD:
+		ctlr = acpi_spi_find_controller_by_adev(acpi_dev_parent(adev));
+		if (!ctlr)
+			break;
+
+		acpi_register_spi_device(ctlr, adev);
+		put_device(&ctlr->dev);
+		break;
+	case ACPI_RECONFIG_DEVICE_REMOVE:
+		if (!acpi_device_enumerated(adev))
+			break;
+
+		spi = acpi_spi_find_device_by_adev(adev);
+		if (!spi)
+			break;
+
+		spi_unregister_device(spi);
+		put_device(&spi->dev);
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block spi_acpi_notifier = {
+	.notifier_call = acpi_spi_notify,
+};
+#else
+extern struct notifier_block spi_acpi_notifier;
+#endif
+
+static int __init spi_init(void)
+{
+	int	status;
+
+	buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
+	if (!buf) {
+		status = -ENOMEM;
+		goto err0;
+	}
+
+	status = bus_register(&spi_bus_type);
+	if (status < 0)
+		goto err1;
+
+	status = class_register(&spi_master_class);
+	if (status < 0)
+		goto err2;
+
+	if (IS_ENABLED(CONFIG_SPI_SLAVE)) {
+		status = class_register(&spi_slave_class);
+		if (status < 0)
+			goto err3;
+	}
+
+	if (IS_ENABLED(CONFIG_OF_DYNAMIC))
+		WARN_ON(of_reconfig_notifier_register(&spi_of_notifier));
+	if (IS_ENABLED(CONFIG_ACPI))
+		WARN_ON(acpi_reconfig_notifier_register(&spi_acpi_notifier));
+
+	return 0;
+
+err3:
+	class_unregister(&spi_master_class);
+err2:
+	bus_unregister(&spi_bus_type);
+err1:
+	kfree(buf);
+	buf = NULL;
+err0:
+	return status;
+}
+
+/*
+ * A board_info is normally registered in arch_initcall(),
+ * but even essential drivers wait till later.
+ *
+ * REVISIT only boardinfo really needs static linking. The rest (device and
+ * driver registration) _could_ be dynamically linked (modular) ... Costs
+ * include needing to have boardinfo data structures be much more public.
+ */
+postcore_initcall(spi_init);