1 files changed, 343 insertions, 0 deletions
diff --git a/drivers/spi/spi-dw-bt1.c b/drivers/spi/spi-dw-bt1.c
new file mode 100644
index 000000000..8f6a1af14
--- /dev/null
+++ b/drivers/spi/spi-dw-bt1.c
@@ -0,0 +1,343 @@
+// SPDX-License-Identifier: GPL-2.0-only
+//
+// Copyright (C) 2020 BAIKAL ELECTRONICS, JSC
+//
+// Authors:
+//   Ramil Zaripov <Ramil.Zaripov@baikalelectronics.ru>
+//   Serge Semin <Sergey.Semin@baikalelectronics.ru>
+//
+// Baikal-T1 DW APB SPI and System Boot SPI driver
+//
+
+#include <linux/clk.h>
+#include <linux/cpumask.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/mux/consumer.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/property.h>
+#include <linux/slab.h>
+#include <linux/spi/spi-mem.h>
+#include <linux/spi/spi.h>
+
+#include "spi-dw.h"
+
+#define BT1_BOOT_DIRMAP		0
+#define BT1_BOOT_REGS		1
+
+struct dw_spi_bt1 {
+	struct dw_spi		dws;
+	struct clk		*clk;
+	struct mux_control	*mux;
+
+#ifdef CONFIG_SPI_DW_BT1_DIRMAP
+	void __iomem		*map;
+	resource_size_t		map_len;
+#endif
+};
+#define to_dw_spi_bt1(_ctlr) \
+	container_of(spi_controller_get_devdata(_ctlr), struct dw_spi_bt1, dws)
+
+typedef int (*dw_spi_bt1_init_cb)(struct platform_device *pdev,
+				    struct dw_spi_bt1 *dwsbt1);
+
+#ifdef CONFIG_SPI_DW_BT1_DIRMAP
+
+static int dw_spi_bt1_dirmap_create(struct spi_mem_dirmap_desc *desc)
+{
+	struct dw_spi_bt1 *dwsbt1 = to_dw_spi_bt1(desc->mem->spi->controller);
+
+	if (!dwsbt1->map ||
+	    !dwsbt1->dws.mem_ops.supports_op(desc->mem, &desc->info.op_tmpl))
+		return -EOPNOTSUPP;
+
+	/*
+	 * Make sure the requested region doesn't go out of the physically
+	 * mapped flash memory bounds and the operation is read-only.
+	 */
+	if (desc->info.offset + desc->info.length > dwsbt1->map_len ||
+	    desc->info.op_tmpl.data.dir != SPI_MEM_DATA_IN)
+		return -EOPNOTSUPP;
+
+	return 0;
+}
+
+/*
+ * Directly mapped SPI memory region is only accessible in the dword chunks.
+ * That's why we have to create a dedicated read-method to copy data from there
+ * to the passed buffer.
+ */
+static void dw_spi_bt1_dirmap_copy_from_map(void *to, void __iomem *from, size_t len)
+{
+	size_t shift, chunk;
+	u32 data;
+
+	/*
+	 * We split the copying up into the next three stages: unaligned head,
+	 * aligned body, unaligned tail.
+	 */
+	shift = (size_t)from & 0x3;
+	if (shift) {
+		chunk = min_t(size_t, 4 - shift, len);
+		data = readl_relaxed(from - shift);
+		memcpy(to, (char *)&data + shift, chunk);
+		from += chunk;
+		to += chunk;
+		len -= chunk;
+	}
+
+	while (len >= 4) {
+		data = readl_relaxed(from);
+		memcpy(to, &data, 4);
+		from += 4;
+		to += 4;
+		len -= 4;
+	}
+
+	if (len) {
+		data = readl_relaxed(from);
+		memcpy(to, &data, len);
+	}
+}
+
+static ssize_t dw_spi_bt1_dirmap_read(struct spi_mem_dirmap_desc *desc,
+				      u64 offs, size_t len, void *buf)
+{
+	struct dw_spi_bt1 *dwsbt1 = to_dw_spi_bt1(desc->mem->spi->controller);
+	struct dw_spi *dws = &dwsbt1->dws;
+	struct spi_mem *mem = desc->mem;
+	struct dw_spi_cfg cfg;
+	int ret;
+
+	/*
+	 * Make sure the requested operation length is valid. Truncate the
+	 * length if it's greater than the length of the MMIO region.
+	 */
+	if (offs >= dwsbt1->map_len || !len)
+		return 0;
+
+	len = min_t(size_t, len, dwsbt1->map_len - offs);
+
+	/* Collect the controller configuration required by the operation */
+	cfg.tmode = SPI_TMOD_EPROMREAD;
+	cfg.dfs = 8;
+	cfg.ndf = 4;
+	cfg.freq = mem->spi->max_speed_hz;
+
+	/* Make sure the corresponding CS is de-asserted on transmission */
+	dw_spi_set_cs(mem->spi, false);
+
+	spi_enable_chip(dws, 0);
+
+	dw_spi_update_config(dws, mem->spi, &cfg);
+
+	spi_umask_intr(dws, SPI_INT_RXFI);
+
+	spi_enable_chip(dws, 1);
+
+	/*
+	 * Enable the transparent mode of the System Boot Controller.
+	 * The SPI core IO should have been locked before calling this method
+	 * so noone would be touching the controller' registers during the
+	 * dirmap operation.
+	 */
+	ret = mux_control_select(dwsbt1->mux, BT1_BOOT_DIRMAP);
+	if (ret)
+		return ret;
+
+	dw_spi_bt1_dirmap_copy_from_map(buf, dwsbt1->map + offs, len);
+
+	mux_control_deselect(dwsbt1->mux);
+
+	dw_spi_set_cs(mem->spi, true);
+
+	ret = dw_spi_check_status(dws, true);
+
+	return ret ?: len;
+}
+
+#endif /* CONFIG_SPI_DW_BT1_DIRMAP */
+
+static int dw_spi_bt1_std_init(struct platform_device *pdev,
+			       struct dw_spi_bt1 *dwsbt1)
+{
+	struct dw_spi *dws = &dwsbt1->dws;
+
+	dws->irq = platform_get_irq(pdev, 0);
+	if (dws->irq < 0)
+		return dws->irq;
+
+	dws->num_cs = 4;
+
+	/*
+	 * Baikal-T1 Normal SPI Controllers don't always keep up with full SPI
+	 * bus speed especially when it comes to the concurrent access to the
+	 * APB bus resources. Thus we have no choice but to set a constraint on
+	 * the SPI bus frequency for the memory operations which require to
+	 * read/write data as fast as possible.
+	 */
+	dws->max_mem_freq = 20000000U;
+
+	dw_spi_dma_setup_generic(dws);
+
+	return 0;
+}
+
+static int dw_spi_bt1_sys_init(struct platform_device *pdev,
+			       struct dw_spi_bt1 *dwsbt1)
+{
+	struct resource *mem __maybe_unused;
+	struct dw_spi *dws = &dwsbt1->dws;
+
+	/*
+	 * Baikal-T1 System Boot Controller is equipped with a mux, which
+	 * switches between the directly mapped SPI flash access mode and
+	 * IO access to the DW APB SSI registers. Note the mux controller
+	 * must be setup to preserve the registers being accessible by default
+	 * (on idle-state).
+	 */
+	dwsbt1->mux = devm_mux_control_get(&pdev->dev, NULL);
+	if (IS_ERR(dwsbt1->mux))
+		return PTR_ERR(dwsbt1->mux);
+
+	/*
+	 * Directly mapped SPI flash memory is a 16MB MMIO region, which can be
+	 * used to access a peripheral memory device just by reading/writing
+	 * data from/to it. Note the system APB bus will stall during each IO
+	 * from/to the dirmap region until the operation is finished. So don't
+	 * use it concurrently with time-critical tasks (like the SPI memory
+	 * operations implemented in the DW APB SSI driver).
+	 */
+#ifdef CONFIG_SPI_DW_BT1_DIRMAP
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	if (mem) {
+		dwsbt1->map = devm_ioremap_resource(&pdev->dev, mem);
+		if (!IS_ERR(dwsbt1->map)) {
+			dwsbt1->map_len = (mem->end - mem->start + 1);
+			dws->mem_ops.dirmap_create = dw_spi_bt1_dirmap_create;
+			dws->mem_ops.dirmap_read = dw_spi_bt1_dirmap_read;
+		} else {
+			dwsbt1->map = NULL;
+		}
+	}
+#endif /* CONFIG_SPI_DW_BT1_DIRMAP */
+
+	/*
+	 * There is no IRQ, no DMA and just one CS available on the System Boot
+	 * SPI controller.
+	 */
+	dws->irq = IRQ_NOTCONNECTED;
+	dws->num_cs = 1;
+
+	/*
+	 * Baikal-T1 System Boot SPI Controller doesn't keep up with the full
+	 * SPI bus speed due to relatively slow APB bus and races for it'
+	 * resources from different CPUs. The situation is worsen by a small
+	 * FIFOs depth (just 8 words). It works better in a single CPU mode
+	 * though, but still tends to be not fast enough at low CPU
+	 * frequencies.
+	 */
+	if (num_possible_cpus() > 1)
+		dws->max_mem_freq = 10000000U;
+	else
+		dws->max_mem_freq = 20000000U;
+
+	return 0;
+}
+
+static int dw_spi_bt1_probe(struct platform_device *pdev)
+{
+	dw_spi_bt1_init_cb init_func;
+	struct dw_spi_bt1 *dwsbt1;
+	struct resource *mem;
+	struct dw_spi *dws;
+	int ret;
+
+	dwsbt1 = devm_kzalloc(&pdev->dev, sizeof(struct dw_spi_bt1), GFP_KERNEL);
+	if (!dwsbt1)
+		return -ENOMEM;
+
+	dws = &dwsbt1->dws;
+
+	dws->regs = devm_platform_get_and_ioremap_resource(pdev, 0, &mem);
+	if (IS_ERR(dws->regs))
+		return PTR_ERR(dws->regs);
+
+	dws->paddr = mem->start;
+
+	dwsbt1->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(dwsbt1->clk))
+		return PTR_ERR(dwsbt1->clk);
+
+	ret = clk_prepare_enable(dwsbt1->clk);
+	if (ret)
+		return ret;
+
+	dws->bus_num = pdev->id;
+	dws->reg_io_width = 4;
+	dws->max_freq = clk_get_rate(dwsbt1->clk);
+	if (!dws->max_freq) {
+		ret = -EINVAL;
+		goto err_disable_clk;
+	}
+
+	init_func = device_get_match_data(&pdev->dev);
+	ret = init_func(pdev, dwsbt1);
+	if (ret)
+		goto err_disable_clk;
+
+	pm_runtime_enable(&pdev->dev);
+
+	ret = dw_spi_add_host(&pdev->dev, dws);
+	if (ret) {
+		pm_runtime_disable(&pdev->dev);
+		goto err_disable_clk;
+	}
+
+	platform_set_drvdata(pdev, dwsbt1);
+
+	return 0;
+
+err_disable_clk:
+	clk_disable_unprepare(dwsbt1->clk);
+
+	return ret;
+}
+
+static int dw_spi_bt1_remove(struct platform_device *pdev)
+{
+	struct dw_spi_bt1 *dwsbt1 = platform_get_drvdata(pdev);
+
+	dw_spi_remove_host(&dwsbt1->dws);
+
+	pm_runtime_disable(&pdev->dev);
+
+	clk_disable_unprepare(dwsbt1->clk);
+
+	return 0;
+}
+
+static const struct of_device_id dw_spi_bt1_of_match[] = {
+	{ .compatible = "baikal,bt1-ssi", .data = dw_spi_bt1_std_init},
+	{ .compatible = "baikal,bt1-sys-ssi", .data = dw_spi_bt1_sys_init},
+	{ }
+};
+MODULE_DEVICE_TABLE(of, dw_spi_bt1_of_match);
+
+static struct platform_driver dw_spi_bt1_driver = {
+	.probe	= dw_spi_bt1_probe,
+	.remove	= dw_spi_bt1_remove,
+	.driver	= {
+		.name		= "bt1-sys-ssi",
+		.of_match_table	= dw_spi_bt1_of_match,
+	},
+};
+module_platform_driver(dw_spi_bt1_driver);
+
+MODULE_AUTHOR("Serge Semin <Sergey.Semin@baikalelectronics.ru>");
+MODULE_DESCRIPTION("Baikal-T1 System Boot SPI Controller driver");
+MODULE_LICENSE("GPL v2");