spi/qspi: Add qspi flash controller

The patch add basic support for the quad spi controller.

QSPI is a kind of spi module that allows single,
dual and quad read access to external spi devices. The module
has a memory mapped interface which provide direct interface
for accessing data form external spi devices.

The patch will configure controller clocks, device control
register and for defining low level transfer apis which
will be used by the spi framework to transfer data to
the slave spi device(flash in this case).

Test details:
-------------
Tested this on dra7 board.
Test1: Ran mtd_stesstest for 40000 iterations.
   - All iterations went through without failure.
Test2: Use mtd utilities:
  - flash_erase to erase the flash device
  - mtd_debug read to read data back.
  - mtd_debug write to write to the data flash.
 diff between the write and read data shows zero.

Acked-by: Felipe Balbi<balbi@ti.com>
Reviewed-by: Felipe Balbi<balbi@ti.com>
Signed-off-by: Sourav Poddar <sourav.poddar@ti.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

Documentation/devicetree/bindings/spi/ti_qspi.txt

@@ -0,0 +1,22 @@
+TI QSPI controller.
+
+Required properties:
+- compatible : should be "ti,dra7xxx-qspi".
+- reg: Should contain QSPI registers location and length.
+- #address-cells, #size-cells : Must be present if the device has sub-nodes
+- ti,hwmods: Name of the hwmod associated to the QSPI
+
+Recommended properties:
+- spi-max-frequency: Definition as per
+                     Documentation/devicetree/bindings/spi/spi-bus.txt
+
+Example:
+
+qspi: qspi@4b300000 {
+	compatible = "ti,dra7xxx-qspi";
+	reg = <0x4b300000 0x100>;
+	#address-cells = <1>;
+	#size-cells = <0>;
+	spi-max-frequency = <25000000>;
+	ti,hwmods = "qspi";
+};

drivers/spi/Kconfig

@@ -285,6 +285,14 @@ config SPI_OMAP24XX
 	  SPI master controller for OMAP24XX and later Multichannel SPI
 	  (McSPI) modules.
 
+config SPI_TI_QSPI
+	tristate "DRA7xxx QSPI controller support"
+	depends on ARCH_OMAP2PLUS || COMPILE_TEST
+	help
+	  QSPI master controller for DRA7xxx used for flash devices.
+	  This device supports single, dual and quad read support, while
+	  it only supports single write mode.
+
 config SPI_OMAP_100K
 	tristate "OMAP SPI 100K"
 	depends on ARCH_OMAP850 || ARCH_OMAP730

drivers/spi/Makefile

@@ -46,6 +46,7 @@ obj-$(CONFIG_SPI_OCTEON)		+= spi-octeon.o
 obj-$(CONFIG_SPI_OMAP_UWIRE)		+= spi-omap-uwire.o
 obj-$(CONFIG_SPI_OMAP_100K)		+= spi-omap-100k.o
 obj-$(CONFIG_SPI_OMAP24XX)		+= spi-omap2-mcspi.o
+obj-$(CONFIG_SPI_TI_QSPI)		+= spi-ti-qspi.o
 obj-$(CONFIG_SPI_ORION)			+= spi-orion.o
 obj-$(CONFIG_SPI_PL022)			+= spi-pl022.o
 obj-$(CONFIG_SPI_PPC4xx)		+= spi-ppc4xx.o

drivers/spi/spi-ti-qspi.c

@@ -0,0 +1,561 @@
+/*
+ * TI QSPI driver
+ *
+ * Copyright (C) 2013 Texas Instruments Incorporated - http://www.ti.com
+ * Author: Sourav Poddar <sourav.poddar@ti.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GPLv2.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR /PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/delay.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
+#include <linux/omap-dma.h>
+#include <linux/platform_device.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/pm_runtime.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/pinctrl/consumer.h>
+
+#include <linux/spi/spi.h>
+
+struct ti_qspi_regs {
+	u32 clkctrl;
+};
+
+struct ti_qspi {
+	struct completion       transfer_complete;
+
+	/* IRQ synchronization */
+	spinlock_t              lock;
+
+	/* list synchronization */
+	struct mutex            list_lock;
+
+	struct spi_master	*master;
+	void __iomem            *base;
+	struct clk		*fclk;
+	struct device           *dev;
+
+	struct ti_qspi_regs     ctx_reg;
+
+	u32 spi_max_frequency;
+	u32 cmd;
+	u32 dc;
+	u32 stat;
+};
+
+#define QSPI_PID			(0x0)
+#define QSPI_SYSCONFIG			(0x10)
+#define QSPI_INTR_STATUS_RAW_SET	(0x20)
+#define QSPI_INTR_STATUS_ENABLED_CLEAR	(0x24)
+#define QSPI_INTR_ENABLE_SET_REG	(0x28)
+#define QSPI_INTR_ENABLE_CLEAR_REG	(0x2c)
+#define QSPI_SPI_CLOCK_CNTRL_REG	(0x40)
+#define QSPI_SPI_DC_REG			(0x44)
+#define QSPI_SPI_CMD_REG		(0x48)
+#define QSPI_SPI_STATUS_REG		(0x4c)
+#define QSPI_SPI_DATA_REG		(0x50)
+#define QSPI_SPI_SETUP0_REG		(0x54)
+#define QSPI_SPI_SWITCH_REG		(0x64)
+#define QSPI_SPI_SETUP1_REG		(0x58)
+#define QSPI_SPI_SETUP2_REG		(0x5c)
+#define QSPI_SPI_SETUP3_REG		(0x60)
+#define QSPI_SPI_DATA_REG_1		(0x68)
+#define QSPI_SPI_DATA_REG_2		(0x6c)
+#define QSPI_SPI_DATA_REG_3		(0x70)
+
+#define QSPI_COMPLETION_TIMEOUT		msecs_to_jiffies(2000)
+
+#define QSPI_FCLK			192000000
+
+/* Clock Control */
+#define QSPI_CLK_EN			(1 << 31)
+#define QSPI_CLK_DIV_MAX		0xffff
+
+/* Command */
+#define QSPI_EN_CS(n)			(n << 28)
+#define QSPI_WLEN(n)			((n - 1) << 19)
+#define QSPI_3_PIN			(1 << 18)
+#define QSPI_RD_SNGL			(1 << 16)
+#define QSPI_WR_SNGL			(2 << 16)
+#define QSPI_RD_DUAL			(3 << 16)
+#define QSPI_RD_QUAD			(7 << 16)
+#define QSPI_INVAL			(4 << 16)
+#define QSPI_WC_CMD_INT_EN			(1 << 14)
+#define QSPI_FLEN(n)			((n - 1) << 0)
+
+/* STATUS REGISTER */
+#define WC				0x02
+
+/* INTERRUPT REGISTER */
+#define QSPI_WC_INT_EN				(1 << 1)
+#define QSPI_WC_INT_DISABLE			(1 << 1)
+
+/* Device Control */
+#define QSPI_DD(m, n)			(m << (3 + n * 8))
+#define QSPI_CKPHA(n)			(1 << (2 + n * 8))
+#define QSPI_CSPOL(n)			(1 << (1 + n * 8))
+#define QSPI_CKPOL(n)			(1 << (n * 8))
+
+#define	QSPI_FRAME			4096
+
+#define QSPI_AUTOSUSPEND_TIMEOUT         2000
+
+static inline unsigned long ti_qspi_read(struct ti_qspi *qspi,
+		unsigned long reg)
+{
+	return readl(qspi->base + reg);
+}
+
+static inline void ti_qspi_write(struct ti_qspi *qspi,
+		unsigned long val, unsigned long reg)
+{
+	writel(val, qspi->base + reg);
+}
+
+static int ti_qspi_setup(struct spi_device *spi)
+{
+	struct ti_qspi	*qspi = spi_master_get_devdata(spi->master);
+	struct ti_qspi_regs *ctx_reg = &qspi->ctx_reg;
+	int clk_div = 0, ret;
+	u32 clk_ctrl_reg, clk_rate, clk_mask;
+
+	if (spi->master->busy) {
+		dev_dbg(qspi->dev, "master busy doing other trasnfers\n");
+		return -EBUSY;
+	}
+
+	if (!qspi->spi_max_frequency) {
+		dev_err(qspi->dev, "spi max frequency not defined\n");
+		return -EINVAL;
+	}
+
+	clk_rate = clk_get_rate(qspi->fclk);
+
+	clk_div = DIV_ROUND_UP(clk_rate, qspi->spi_max_frequency) - 1;
+
+	if (clk_div < 0) {
+		dev_dbg(qspi->dev, "clock divider < 0, using /1 divider\n");
+		return -EINVAL;
+	}
+
+	if (clk_div > QSPI_CLK_DIV_MAX) {
+		dev_dbg(qspi->dev, "clock divider >%d , using /%d divider\n",
+				QSPI_CLK_DIV_MAX, QSPI_CLK_DIV_MAX + 1);
+		return -EINVAL;
+	}
+
+	dev_dbg(qspi->dev, "hz: %d, clock divider %d\n",
+			qspi->spi_max_frequency, clk_div);
+
+	ret = pm_runtime_get_sync(qspi->dev);
+	if (ret) {
+		dev_err(qspi->dev, "pm_runtime_get_sync() failed\n");
+		return ret;
+	}
+
+	clk_ctrl_reg = ti_qspi_read(qspi, QSPI_SPI_CLOCK_CNTRL_REG);
+
+	clk_ctrl_reg &= ~QSPI_CLK_EN;
+
+	/* disable SCLK */
+	ti_qspi_write(qspi, clk_ctrl_reg, QSPI_SPI_CLOCK_CNTRL_REG);
+
+	/* enable SCLK */
+	clk_mask = QSPI_CLK_EN | clk_div;
+	ti_qspi_write(qspi, clk_mask, QSPI_SPI_CLOCK_CNTRL_REG);
+	ctx_reg->clkctrl = clk_mask;
+
+	pm_runtime_mark_last_busy(qspi->dev);
+	ret = pm_runtime_put_autosuspend(qspi->dev);
+	if (ret < 0) {
+		dev_err(qspi->dev, "pm_runtime_put_autosuspend() failed\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static void ti_qspi_restore_ctx(struct ti_qspi *qspi)
+{
+	struct ti_qspi_regs *ctx_reg = &qspi->ctx_reg;
+
+	ti_qspi_write(qspi, ctx_reg->clkctrl, QSPI_SPI_CLOCK_CNTRL_REG);
+}
+
+static int qspi_write_msg(struct ti_qspi *qspi, struct spi_transfer *t)
+{
+	int wlen, count, ret;
+	unsigned int cmd;
+	const u8 *txbuf;
+
+	txbuf = t->tx_buf;
+	cmd = qspi->cmd | QSPI_WR_SNGL;
+	count = t->len;
+	wlen = t->bits_per_word;
+
+	while (count) {
+		switch (wlen) {
+		case 8:
+			dev_dbg(qspi->dev, "tx cmd %08x dc %08x data %02x\n",
+					cmd, qspi->dc, *txbuf);
+			writeb(*txbuf, qspi->base + QSPI_SPI_DATA_REG);
+			ti_qspi_write(qspi, cmd, QSPI_SPI_CMD_REG);
+			ret = wait_for_completion_timeout(&qspi->transfer_complete,
+					QSPI_COMPLETION_TIMEOUT);
+			if (ret == 0) {
+				dev_err(qspi->dev, "write timed out\n");
+				return -ETIMEDOUT;
+			}
+			txbuf += 1;
+			count -= 1;
+			break;
+		case 16:
+			dev_dbg(qspi->dev, "tx cmd %08x dc %08x data %04x\n",
+					cmd, qspi->dc, *txbuf);
+			writew(*((u16 *)txbuf), qspi->base + QSPI_SPI_DATA_REG);
+			ti_qspi_write(qspi, cmd, QSPI_SPI_CMD_REG);
+			ret = wait_for_completion_timeout(&qspi->transfer_complete,
+				QSPI_COMPLETION_TIMEOUT);
+			if (ret == 0) {
+				dev_err(qspi->dev, "write timed out\n");
+				return -ETIMEDOUT;
+			}
+			txbuf += 2;
+			count -= 2;
+			break;
+		case 32:
+			dev_dbg(qspi->dev, "tx cmd %08x dc %08x data %08x\n",
+					cmd, qspi->dc, *txbuf);
+			writel(*((u32 *)txbuf), qspi->base + QSPI_SPI_DATA_REG);
+			ti_qspi_write(qspi, cmd, QSPI_SPI_CMD_REG);
+			ret = wait_for_completion_timeout(&qspi->transfer_complete,
+				QSPI_COMPLETION_TIMEOUT);
+			if (ret == 0) {
+				dev_err(qspi->dev, "write timed out\n");
+				return -ETIMEDOUT;
+			}
+			txbuf += 4;
+			count -= 4;
+			break;
+		}
+	}
+
+	return 0;
+}
+
+static int qspi_read_msg(struct ti_qspi *qspi, struct spi_transfer *t)
+{
+	int wlen, count, ret;
+	unsigned int cmd;
+	u8 *rxbuf;
+
+	rxbuf = t->rx_buf;
+	cmd = qspi->cmd | QSPI_RD_SNGL;
+	count = t->len;
+	wlen = t->bits_per_word;
+
+	while (count) {
+		dev_dbg(qspi->dev, "rx cmd %08x dc %08x\n", cmd, qspi->dc);
+		ti_qspi_write(qspi, cmd, QSPI_SPI_CMD_REG);
+		ret = wait_for_completion_timeout(&qspi->transfer_complete,
+				QSPI_COMPLETION_TIMEOUT);
+		if (ret == 0) {
+			dev_err(qspi->dev, "read timed out\n");
+			return -ETIMEDOUT;
+		}
+		switch (wlen) {
+		case 8:
+			*rxbuf = readb(qspi->base + QSPI_SPI_DATA_REG);
+			rxbuf += 1;
+			count -= 1;
+			break;
+		case 16:
+			*((u16 *)rxbuf) = readw(qspi->base + QSPI_SPI_DATA_REG);
+			rxbuf += 2;
+			count -= 2;
+			break;
+		case 32:
+			*((u32 *)rxbuf) = readl(qspi->base + QSPI_SPI_DATA_REG);
+			rxbuf += 4;
+			count -= 4;
+			break;
+		}
+	}
+
+	return 0;
+}
+
+static int qspi_transfer_msg(struct ti_qspi *qspi, struct spi_transfer *t)
+{
+	int ret;
+
+	if (t->tx_buf) {
+		ret = qspi_write_msg(qspi, t);
+		if (ret) {
+			dev_dbg(qspi->dev, "Error while writing\n");
+			return ret;
+		}
+	}
+
+	if (t->rx_buf) {
+		ret = qspi_read_msg(qspi, t);
+		if (ret) {
+			dev_dbg(qspi->dev, "Error while reading\n");
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+static int ti_qspi_start_transfer_one(struct spi_master *master,
+		struct spi_message *m)
+{
+	struct ti_qspi *qspi = spi_master_get_devdata(master);
+	struct spi_device *spi = m->spi;
+	struct spi_transfer *t;
+	int status = 0, ret;
+	int frame_length;
+
+	/* setup device control reg */
+	qspi->dc = 0;
+
+	if (spi->mode & SPI_CPHA)
+		qspi->dc |= QSPI_CKPHA(spi->chip_select);
+	if (spi->mode & SPI_CPOL)
+		qspi->dc |= QSPI_CKPOL(spi->chip_select);
+	if (spi->mode & SPI_CS_HIGH)
+		qspi->dc |= QSPI_CSPOL(spi->chip_select);
+
+	frame_length = (m->frame_length << 3) / spi->bits_per_word;
+
+	frame_length = clamp(frame_length, 0, QSPI_FRAME);
+
+	/* setup command reg */
+	qspi->cmd = 0;
+	qspi->cmd |= QSPI_EN_CS(spi->chip_select);
+	qspi->cmd |= QSPI_FLEN(frame_length);
+	qspi->cmd |= QSPI_WC_CMD_INT_EN;
+
+	ti_qspi_write(qspi, QSPI_WC_INT_EN, QSPI_INTR_ENABLE_SET_REG);
+	ti_qspi_write(qspi, qspi->dc, QSPI_SPI_DC_REG);
+
+	mutex_lock(&qspi->list_lock);
+
+	list_for_each_entry(t, &m->transfers, transfer_list) {
+		qspi->cmd |= QSPI_WLEN(t->bits_per_word);
+
+		ret = qspi_transfer_msg(qspi, t);
+		if (ret) {
+			dev_dbg(qspi->dev, "transfer message failed\n");
+			return -EINVAL;
+		}
+
+		m->actual_length += t->len;
+	}
+
+	mutex_unlock(&qspi->list_lock);
+
+	m->status = status;
+	spi_finalize_current_message(master);
+
+	ti_qspi_write(qspi, qspi->cmd | QSPI_INVAL, QSPI_SPI_CMD_REG);
+
+	return status;
+}
+
+static irqreturn_t ti_qspi_isr(int irq, void *dev_id)
+{
+	struct ti_qspi *qspi = dev_id;
+	u16 int_stat;
+
+	irqreturn_t ret = IRQ_HANDLED;
+
+	spin_lock(&qspi->lock);
+
+	int_stat = ti_qspi_read(qspi, QSPI_INTR_STATUS_ENABLED_CLEAR);
+	qspi->stat = ti_qspi_read(qspi, QSPI_SPI_STATUS_REG);
+
+	if (!int_stat) {
+		dev_dbg(qspi->dev, "No IRQ triggered\n");
+		ret = IRQ_NONE;
+		goto out;
+	}
+
+	ret = IRQ_WAKE_THREAD;
+
+	ti_qspi_write(qspi, QSPI_WC_INT_DISABLE, QSPI_INTR_ENABLE_CLEAR_REG);
+	ti_qspi_write(qspi, QSPI_WC_INT_DISABLE,
+				QSPI_INTR_STATUS_ENABLED_CLEAR);
+
+out:
+	spin_unlock(&qspi->lock);
+
+	return ret;
+}
+
+static irqreturn_t ti_qspi_threaded_isr(int this_irq, void *dev_id)
+{
+	struct ti_qspi *qspi = dev_id;
+	unsigned long flags;
+
+	spin_lock_irqsave(&qspi->lock, flags);
+
+	if (qspi->stat & WC)
+		complete(&qspi->transfer_complete);
+
+	spin_unlock_irqrestore(&qspi->lock, flags);
+
+	ti_qspi_write(qspi, QSPI_WC_INT_EN, QSPI_INTR_ENABLE_SET_REG);
+
+	return IRQ_HANDLED;
+}
+
+static int ti_qspi_runtime_resume(struct device *dev)
+{
+	struct ti_qspi      *qspi;
+	struct spi_master       *master;
+
+	master = dev_get_drvdata(dev);
+	qspi = spi_master_get_devdata(master);
+	ti_qspi_restore_ctx(qspi);
+
+	return 0;
+}
+
+static const struct of_device_id ti_qspi_match[] = {
+	{.compatible = "ti,dra7xxx-qspi" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, dra7xxx_qspi_match);
+
+static int ti_qspi_probe(struct platform_device *pdev)
+{
+	struct  ti_qspi *qspi;
+	struct spi_master *master;
+	struct resource         *r;
+	struct device_node *np = pdev->dev.of_node;
+	u32 max_freq;
+	int ret = 0, num_cs, irq;
+
+	master = spi_alloc_master(&pdev->dev, sizeof(*qspi));
+	if (!master)
+		return -ENOMEM;
+
+	master->mode_bits = SPI_CPOL | SPI_CPHA;
+
+	master->bus_num = -1;
+	master->flags = SPI_MASTER_HALF_DUPLEX;
+	master->setup = ti_qspi_setup;
+	master->auto_runtime_pm = true;
+	master->transfer_one_message = ti_qspi_start_transfer_one;
+	master->dev.of_node = pdev->dev.of_node;
+	master->bits_per_word_mask = BIT(32 - 1) | BIT(16 - 1) | BIT(8 - 1);
+
+	if (!of_property_read_u32(np, "num-cs", &num_cs))
+		master->num_chipselect = num_cs;
+
+	platform_set_drvdata(pdev, master);
+
+	qspi = spi_master_get_devdata(master);
+	qspi->master = master;
+	qspi->dev = &pdev->dev;
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "no irq resource?\n");
+		return irq;
+	}
+
+	spin_lock_init(&qspi->lock);
+	mutex_init(&qspi->list_lock);
+
+	qspi->base = devm_ioremap_resource(&pdev->dev, r);
+	if (IS_ERR(qspi->base)) {
+		ret = PTR_ERR(qspi->base);
+		goto free_master;
+	}
+
+	ret = devm_request_threaded_irq(&pdev->dev, irq, ti_qspi_isr,
+			ti_qspi_threaded_isr, 0,
+			dev_name(&pdev->dev), qspi);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to register ISR for IRQ %d\n",
+				irq);
+		goto free_master;
+	}
+
+	qspi->fclk = devm_clk_get(&pdev->dev, "fck");
+	if (IS_ERR(qspi->fclk)) {
+		ret = PTR_ERR(qspi->fclk);
+		dev_err(&pdev->dev, "could not get clk: %d\n", ret);
+	}
+
+	init_completion(&qspi->transfer_complete);
+
+	pm_runtime_use_autosuspend(&pdev->dev);
+	pm_runtime_set_autosuspend_delay(&pdev->dev, QSPI_AUTOSUSPEND_TIMEOUT);
+	pm_runtime_enable(&pdev->dev);
+
+	if (!of_property_read_u32(np, "spi-max-frequency", &max_freq))
+		qspi->spi_max_frequency = max_freq;
+
+	ret = spi_register_master(master);
+	if (ret)
+		goto free_master;
+
+	return 0;
+
+free_master:
+	spi_master_put(master);
+	return ret;
+}
+
+static int ti_qspi_remove(struct platform_device *pdev)
+{
+	struct	ti_qspi *qspi = platform_get_drvdata(pdev);
+
+	spi_unregister_master(qspi->master);
+
+	return 0;
+}
+
+static const struct dev_pm_ops ti_qspi_pm_ops = {
+	.runtime_resume = ti_qspi_runtime_resume,
+};
+
+static struct platform_driver ti_qspi_driver = {
+	.probe	= ti_qspi_probe,
+	.remove	= ti_qspi_remove,
+	.driver = {
+		.name	= "ti,dra7xxx-qspi",
+		.owner	= THIS_MODULE,
+		.pm =   &ti_qspi_pm_ops,
+		.of_match_table = ti_qspi_match,
+	}
+};
+
+module_platform_driver(ti_qspi_driver);
+
+MODULE_AUTHOR("Sourav Poddar <sourav.poddar@ti.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("TI QSPI controller driver");