Adding upstream version 5.10.209.upstream/5.10.209upstream

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

1 files changed, 450 insertions, 0 deletions

diff --git a/drivers/spi/spi-gpio.c b/drivers/spi/spi-gpio.c
new file mode 100644
index 000000000..3ffdab6ca
--- /dev/null
+++ b/drivers/spi/spi-gpio.c
@@ -0,0 +1,450 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * SPI master driver using generic bitbanged GPIO
+ *
+ * Copyright (C) 2006,2008 David Brownell
+ * Copyright (C) 2017 Linus Walleij
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/gpio/consumer.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+
+#include <linux/spi/spi.h>
+#include <linux/spi/spi_bitbang.h>
+#include <linux/spi/spi_gpio.h>
+
+
+/*
+ * This bitbanging SPI master driver should help make systems usable
+ * when a native hardware SPI engine is not available, perhaps because
+ * its driver isn't yet working or because the I/O pins it requires
+ * are used for other purposes.
+ *
+ * platform_device->driver_data ... points to spi_gpio
+ *
+ * spi->controller_state ... reserved for bitbang framework code
+ *
+ * spi->master->dev.driver_data ... points to spi_gpio->bitbang
+ */
+
+struct spi_gpio {
+	struct spi_bitbang		bitbang;
+	struct gpio_desc		*sck;
+	struct gpio_desc		*miso;
+	struct gpio_desc		*mosi;
+	struct gpio_desc		**cs_gpios;
+};
+
+/*----------------------------------------------------------------------*/
+
+/*
+ * Because the overhead of going through four GPIO procedure calls
+ * per transferred bit can make performance a problem, this code
+ * is set up so that you can use it in either of two ways:
+ *
+ *   - The slow generic way:  set up platform_data to hold the GPIO
+ *     numbers used for MISO/MOSI/SCK, and issue procedure calls for
+ *     each of them.  This driver can handle several such busses.
+ *
+ *   - The quicker inlined way:  only helps with platform GPIO code
+ *     that inlines operations for constant GPIOs.  This can give
+ *     you tight (fast!) inner loops, but each such bus needs a
+ *     new driver.  You'll define a new C file, with Makefile and
+ *     Kconfig support; the C code can be a total of six lines:
+ *
+ *		#define DRIVER_NAME	"myboard_spi2"
+ *		#define	SPI_MISO_GPIO	119
+ *		#define	SPI_MOSI_GPIO	120
+ *		#define	SPI_SCK_GPIO	121
+ *		#define	SPI_N_CHIPSEL	4
+ *		#include "spi-gpio.c"
+ */
+
+#ifndef DRIVER_NAME
+#define DRIVER_NAME	"spi_gpio"
+
+#define GENERIC_BITBANG	/* vs tight inlines */
+
+#endif
+
+/*----------------------------------------------------------------------*/
+
+static inline struct spi_gpio *__pure
+spi_to_spi_gpio(const struct spi_device *spi)
+{
+	const struct spi_bitbang	*bang;
+	struct spi_gpio			*spi_gpio;
+
+	bang = spi_master_get_devdata(spi->master);
+	spi_gpio = container_of(bang, struct spi_gpio, bitbang);
+	return spi_gpio;
+}
+
+/* These helpers are in turn called by the bitbang inlines */
+static inline void setsck(const struct spi_device *spi, int is_on)
+{
+	struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
+
+	gpiod_set_value_cansleep(spi_gpio->sck, is_on);
+}
+
+static inline void setmosi(const struct spi_device *spi, int is_on)
+{
+	struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
+
+	gpiod_set_value_cansleep(spi_gpio->mosi, is_on);
+}
+
+static inline int getmiso(const struct spi_device *spi)
+{
+	struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
+
+	if (spi->mode & SPI_3WIRE)
+		return !!gpiod_get_value_cansleep(spi_gpio->mosi);
+	else
+		return !!gpiod_get_value_cansleep(spi_gpio->miso);
+}
+
+/*
+ * NOTE:  this clocks "as fast as we can".  It "should" be a function of the
+ * requested device clock.  Software overhead means we usually have trouble
+ * reaching even one Mbit/sec (except when we can inline bitops), so for now
+ * we'll just assume we never need additional per-bit slowdowns.
+ */
+#define spidelay(nsecs)	do {} while (0)
+
+#include "spi-bitbang-txrx.h"
+
+/*
+ * These functions can leverage inline expansion of GPIO calls to shrink
+ * costs for a txrx bit, often by factors of around ten (by instruction
+ * count).  That is particularly visible for larger word sizes, but helps
+ * even with default 8-bit words.
+ *
+ * REVISIT overheads calling these functions for each word also have
+ * significant performance costs.  Having txrx_bufs() calls that inline
+ * the txrx_word() logic would help performance, e.g. on larger blocks
+ * used with flash storage or MMC/SD.  There should also be ways to make
+ * GCC be less stupid about reloading registers inside the I/O loops,
+ * even without inlined GPIO calls; __attribute__((hot)) on GCC 4.3?
+ */
+
+static u32 spi_gpio_txrx_word_mode0(struct spi_device *spi,
+		unsigned nsecs, u32 word, u8 bits, unsigned flags)
+{
+	return bitbang_txrx_be_cpha0(spi, nsecs, 0, flags, word, bits);
+}
+
+static u32 spi_gpio_txrx_word_mode1(struct spi_device *spi,
+		unsigned nsecs, u32 word, u8 bits, unsigned flags)
+{
+	return bitbang_txrx_be_cpha1(spi, nsecs, 0, flags, word, bits);
+}
+
+static u32 spi_gpio_txrx_word_mode2(struct spi_device *spi,
+		unsigned nsecs, u32 word, u8 bits, unsigned flags)
+{
+	return bitbang_txrx_be_cpha0(spi, nsecs, 1, flags, word, bits);
+}
+
+static u32 spi_gpio_txrx_word_mode3(struct spi_device *spi,
+		unsigned nsecs, u32 word, u8 bits, unsigned flags)
+{
+	return bitbang_txrx_be_cpha1(spi, nsecs, 1, flags, word, bits);
+}
+
+/*
+ * These functions do not call setmosi or getmiso if respective flag
+ * (SPI_MASTER_NO_RX or SPI_MASTER_NO_TX) is set, so they are safe to
+ * call when such pin is not present or defined in the controller.
+ * A separate set of callbacks is defined to get highest possible
+ * speed in the generic case (when both MISO and MOSI lines are
+ * available), as optimiser will remove the checks when argument is
+ * constant.
+ */
+
+static u32 spi_gpio_spec_txrx_word_mode0(struct spi_device *spi,
+		unsigned nsecs, u32 word, u8 bits, unsigned flags)
+{
+	flags = spi->master->flags;
+	return bitbang_txrx_be_cpha0(spi, nsecs, 0, flags, word, bits);
+}
+
+static u32 spi_gpio_spec_txrx_word_mode1(struct spi_device *spi,
+		unsigned nsecs, u32 word, u8 bits, unsigned flags)
+{
+	flags = spi->master->flags;
+	return bitbang_txrx_be_cpha1(spi, nsecs, 0, flags, word, bits);
+}
+
+static u32 spi_gpio_spec_txrx_word_mode2(struct spi_device *spi,
+		unsigned nsecs, u32 word, u8 bits, unsigned flags)
+{
+	flags = spi->master->flags;
+	return bitbang_txrx_be_cpha0(spi, nsecs, 1, flags, word, bits);
+}
+
+static u32 spi_gpio_spec_txrx_word_mode3(struct spi_device *spi,
+		unsigned nsecs, u32 word, u8 bits, unsigned flags)
+{
+	flags = spi->master->flags;
+	return bitbang_txrx_be_cpha1(spi, nsecs, 1, flags, word, bits);
+}
+
+/*----------------------------------------------------------------------*/
+
+static void spi_gpio_chipselect(struct spi_device *spi, int is_active)
+{
+	struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
+
+	/* set initial clock line level */
+	if (is_active)
+		gpiod_set_value_cansleep(spi_gpio->sck, spi->mode & SPI_CPOL);
+
+	/* Drive chip select line, if we have one */
+	if (spi_gpio->cs_gpios) {
+		struct gpio_desc *cs = spi_gpio->cs_gpios[spi->chip_select];
+
+		/* SPI chip selects are normally active-low */
+		gpiod_set_value_cansleep(cs, (spi->mode & SPI_CS_HIGH) ? is_active : !is_active);
+	}
+}
+
+static int spi_gpio_setup(struct spi_device *spi)
+{
+	struct gpio_desc	*cs;
+	int			status = 0;
+	struct spi_gpio		*spi_gpio = spi_to_spi_gpio(spi);
+
+	/*
+	 * The CS GPIOs have already been
+	 * initialized from the descriptor lookup.
+	 */
+	if (spi_gpio->cs_gpios) {
+		cs = spi_gpio->cs_gpios[spi->chip_select];
+		if (!spi->controller_state && cs)
+			status = gpiod_direction_output(cs,
+						  !(spi->mode & SPI_CS_HIGH));
+	}
+
+	if (!status)
+		status = spi_bitbang_setup(spi);
+
+	return status;
+}
+
+static int spi_gpio_set_direction(struct spi_device *spi, bool output)
+{
+	struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
+	int ret;
+
+	if (output)
+		return gpiod_direction_output(spi_gpio->mosi, 1);
+
+	/*
+	 * Only change MOSI to an input if using 3WIRE mode.
+	 * Otherwise, MOSI could be left floating if there is
+	 * no pull resistor connected to the I/O pin, or could
+	 * be left logic high if there is a pull-up. Transmitting
+	 * logic high when only clocking MISO data in can put some
+	 * SPI devices in to a bad state.
+	 */
+	if (spi->mode & SPI_3WIRE) {
+		ret = gpiod_direction_input(spi_gpio->mosi);
+		if (ret)
+			return ret;
+	}
+	/*
+	 * Send a turnaround high impedance cycle when switching
+	 * from output to input. Theoretically there should be
+	 * a clock delay here, but as has been noted above, the
+	 * nsec delay function for bit-banged GPIO is simply
+	 * {} because bit-banging just doesn't get fast enough
+	 * anyway.
+	 */
+	if (spi->mode & SPI_3WIRE_HIZ) {
+		gpiod_set_value_cansleep(spi_gpio->sck,
+					 !(spi->mode & SPI_CPOL));
+		gpiod_set_value_cansleep(spi_gpio->sck,
+					 !!(spi->mode & SPI_CPOL));
+	}
+	return 0;
+}
+
+static void spi_gpio_cleanup(struct spi_device *spi)
+{
+	spi_bitbang_cleanup(spi);
+}
+
+/*
+ * It can be convenient to use this driver with pins that have alternate
+ * functions associated with a "native" SPI controller if a driver for that
+ * controller is not available, or is missing important functionality.
+ *
+ * On platforms which can do so, configure MISO with a weak pullup unless
+ * there's an external pullup on that signal.  That saves power by avoiding
+ * floating signals.  (A weak pulldown would save power too, but many
+ * drivers expect to see all-ones data as the no slave "response".)
+ */
+static int spi_gpio_request(struct device *dev, struct spi_gpio *spi_gpio)
+{
+	spi_gpio->mosi = devm_gpiod_get_optional(dev, "mosi", GPIOD_OUT_LOW);
+	if (IS_ERR(spi_gpio->mosi))
+		return PTR_ERR(spi_gpio->mosi);
+
+	spi_gpio->miso = devm_gpiod_get_optional(dev, "miso", GPIOD_IN);
+	if (IS_ERR(spi_gpio->miso))
+		return PTR_ERR(spi_gpio->miso);
+
+	spi_gpio->sck = devm_gpiod_get(dev, "sck", GPIOD_OUT_LOW);
+	return PTR_ERR_OR_ZERO(spi_gpio->sck);
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id spi_gpio_dt_ids[] = {
+	{ .compatible = "spi-gpio" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, spi_gpio_dt_ids);
+
+static int spi_gpio_probe_dt(struct platform_device *pdev,
+			     struct spi_master *master)
+{
+	master->dev.of_node = pdev->dev.of_node;
+	master->use_gpio_descriptors = true;
+
+	return 0;
+}
+#else
+static inline int spi_gpio_probe_dt(struct platform_device *pdev,
+				    struct spi_master *master)
+{
+	return 0;
+}
+#endif
+
+static int spi_gpio_probe_pdata(struct platform_device *pdev,
+				struct spi_master *master)
+{
+	struct device *dev = &pdev->dev;
+	struct spi_gpio_platform_data *pdata = dev_get_platdata(dev);
+	struct spi_gpio *spi_gpio = spi_master_get_devdata(master);
+	int i;
+
+#ifdef GENERIC_BITBANG
+	if (!pdata || !pdata->num_chipselect)
+		return -ENODEV;
+#endif
+	/*
+	 * The master needs to think there is a chipselect even if not
+	 * connected
+	 */
+	master->num_chipselect = pdata->num_chipselect ?: 1;
+
+	spi_gpio->cs_gpios = devm_kcalloc(dev, master->num_chipselect,
+					  sizeof(*spi_gpio->cs_gpios),
+					  GFP_KERNEL);
+	if (!spi_gpio->cs_gpios)
+		return -ENOMEM;
+
+	for (i = 0; i < master->num_chipselect; i++) {
+		spi_gpio->cs_gpios[i] = devm_gpiod_get_index(dev, "cs", i,
+							     GPIOD_OUT_HIGH);
+		if (IS_ERR(spi_gpio->cs_gpios[i]))
+			return PTR_ERR(spi_gpio->cs_gpios[i]);
+	}
+
+	return 0;
+}
+
+static int spi_gpio_probe(struct platform_device *pdev)
+{
+	int				status;
+	struct spi_master		*master;
+	struct spi_gpio			*spi_gpio;
+	struct device			*dev = &pdev->dev;
+	struct spi_bitbang		*bb;
+
+	master = devm_spi_alloc_master(dev, sizeof(*spi_gpio));
+	if (!master)
+		return -ENOMEM;
+
+	if (pdev->dev.of_node)
+		status = spi_gpio_probe_dt(pdev, master);
+	else
+		status = spi_gpio_probe_pdata(pdev, master);
+
+	if (status)
+		return status;
+
+	spi_gpio = spi_master_get_devdata(master);
+
+	status = spi_gpio_request(dev, spi_gpio);
+	if (status)
+		return status;
+
+	master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 32);
+	master->mode_bits = SPI_3WIRE | SPI_3WIRE_HIZ | SPI_CPHA | SPI_CPOL |
+			    SPI_CS_HIGH;
+	if (!spi_gpio->mosi) {
+		/* HW configuration without MOSI pin
+		 *
+		 * No setting SPI_MASTER_NO_RX here - if there is only
+		 * a MOSI pin connected the host can still do RX by
+		 * changing the direction of the line.
+		 */
+		master->flags = SPI_MASTER_NO_TX;
+	}
+
+	master->bus_num = pdev->id;
+	master->setup = spi_gpio_setup;
+	master->cleanup = spi_gpio_cleanup;
+
+	bb = &spi_gpio->bitbang;
+	bb->master = master;
+	/*
+	 * There is some additional business, apart from driving the CS GPIO
+	 * line, that we need to do on selection. This makes the local
+	 * callback for chipselect always get called.
+	 */
+	master->flags |= SPI_MASTER_GPIO_SS;
+	bb->chipselect = spi_gpio_chipselect;
+	bb->set_line_direction = spi_gpio_set_direction;
+
+	if (master->flags & SPI_MASTER_NO_TX) {
+		bb->txrx_word[SPI_MODE_0] = spi_gpio_spec_txrx_word_mode0;
+		bb->txrx_word[SPI_MODE_1] = spi_gpio_spec_txrx_word_mode1;
+		bb->txrx_word[SPI_MODE_2] = spi_gpio_spec_txrx_word_mode2;
+		bb->txrx_word[SPI_MODE_3] = spi_gpio_spec_txrx_word_mode3;
+	} else {
+		bb->txrx_word[SPI_MODE_0] = spi_gpio_txrx_word_mode0;
+		bb->txrx_word[SPI_MODE_1] = spi_gpio_txrx_word_mode1;
+		bb->txrx_word[SPI_MODE_2] = spi_gpio_txrx_word_mode2;
+		bb->txrx_word[SPI_MODE_3] = spi_gpio_txrx_word_mode3;
+	}
+	bb->setup_transfer = spi_bitbang_setup_transfer;
+
+	status = spi_bitbang_init(&spi_gpio->bitbang);
+	if (status)
+		return status;
+
+	return devm_spi_register_master(&pdev->dev, master);
+}
+
+MODULE_ALIAS("platform:" DRIVER_NAME);
+
+static struct platform_driver spi_gpio_driver = {
+	.driver = {
+		.name	= DRIVER_NAME,
+		.of_match_table = of_match_ptr(spi_gpio_dt_ids),
+	},
+	.probe		= spi_gpio_probe,
+};
+module_platform_driver(spi_gpio_driver);
+
+MODULE_DESCRIPTION("SPI master driver using generic bitbanged GPIO ");
+MODULE_AUTHOR("David Brownell");
+MODULE_LICENSE("GPL");