[PATCH] spi: tegra: add spi driver for sflash controller

[PATCH] spi: tegra: add spi driver for sflash controller

[Laxman Dewangan]

Nvidia's Tegra20 have the SPI (SFLASH) controller to
interface with spi flash device which is used for system
boot. Add the spi driver for this controller.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
---
 .../bindings/spi/nvidia,tegra20-sflash.txt         |   26 +
 drivers/spi/Kconfig                                |    8 +
 drivers/spi/Makefile                               |    1 +
 drivers/spi/spi-tegra20-sflash.c                   |  674 ++++++++++++++++++++
 4 files changed, 709 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/spi/nvidia,tegra20-sflash.txt
 create mode 100644 drivers/spi/spi-tegra20-sflash.c

diff --git a/Documentation/devicetree/bindings/spi/nvidia,tegra20-sflash.txt b/Documentation/devicetree/bindings/spi/nvidia,tegra20-sflash.txt
new file mode 100644
index 0000000..8cf24f6
--- /dev/null
+++ b/Documentation/devicetree/bindings/spi/nvidia,tegra20-sflash.txt
@@ -0,0 +1,26 @@
+NVIDIA Tegra20 SFLASH controller.
+
+Required properties:
+- compatible : should be "nvidia,tegra20-sflash".
+- reg: Should contain SFLASH registers location and length.
+- interrupts: Should contain SFLASH interrupts.
+- nvidia,dma-request-selector : The Tegra DMA controller's phandle and
+  request selector for this SFLASH controller.
+
+Recommended properties:
+- spi-max-frequency: Definition as per
+                     Documentation/devicetree/bindings/spi/spi-bus.txt
+
+Example:
+
+spi@7000d600 {
+	compatible = "nvidia,tegra20-sflash";
+	reg = <0x7000c380 0x80>;
+	interrupts = <0 39 0x04>;
+	nvidia,dma-request-selector = <&apbdma 16>;
+	spi-max-frequency = <25000000>;
+	#address-cells = <1>;
+	#size-cells = <0>;
+	status = "disabled";
+};
+
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 25290d9..3cbc9fb 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -385,6 +385,14 @@ config SPI_MXS
 	help
 	  SPI driver for Freescale MXS devices.
 
+config SPI_TEGRA20_SFLASH
+	tristate "Nvidia Tegra20 Serial flash Controller"
+	depends on ARCH_TEGRA
+	help
+	  SPI driver for Nvidia Tegra20 Serial flash Controller interface.
+	  The main usecase of this controller is to use spi flash as boot
+	  device.
+
 config SPI_TEGRA20_SLINK
 	tristate "Nvidia Tegra20/Tegra30 SLINK Controller"
 	depends on ARCH_TEGRA && TEGRA20_APB_DMA
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index f87c0f1..9f6b3d8 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -60,6 +60,7 @@ obj-$(CONFIG_SPI_SH_MSIOF)		+= spi-sh-msiof.o
 obj-$(CONFIG_SPI_SH_SCI)		+= spi-sh-sci.o
 obj-$(CONFIG_SPI_SIRF)		+= spi-sirf.o
 obj-$(CONFIG_SPI_STMP3XXX)		+= spi-stmp.o
+obj-$(CONFIG_SPI_TEGRA20_SFLASH)	+= spi-tegra20-sflash.o
 obj-$(CONFIG_SPI_TEGRA20_SLINK)		+= spi-tegra20-slink.o
 obj-$(CONFIG_SPI_TI_SSP)		+= spi-ti-ssp.o
 obj-$(CONFIG_SPI_TLE62X0)		+= spi-tle62x0.o
diff --git a/drivers/spi/spi-tegra20-sflash.c b/drivers/spi/spi-tegra20-sflash.c
new file mode 100644
index 0000000..db7ddc9
--- /dev/null
+++ b/drivers/spi/spi-tegra20-sflash.c
@@ -0,0 +1,674 @@
+/*
+ * SPI driver for Nvidia's Tegra20 Serial Flash Controller.
+ *
+ * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/kthread.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/spi-tegra.h>
+#include <mach/clk.h>
+
+#define SPI_COMMAND				0x000
+#define SPI_GO					BIT(30)
+#define SPI_M_S					BIT(28)
+#define SPI_ACTIVE_SCLK_MASK			(0x3 << 26)
+#define SPI_ACTIVE_SCLK_DRIVE_LOW		(0 << 26)
+#define SPI_ACTIVE_SCLK_DRIVE_HIGH		(1 << 26)
+#define SPI_ACTIVE_SCLK_PULL_LOW		(2 << 26)
+#define SPI_ACTIVE_SCLK_PULL_HIGH		(3 << 26)
+
+#define SPI_CK_SDA_FALLING			(1 << 21)
+#define SPI_CK_SDA_RISING			(0 << 21)
+#define SPI_CK_SDA_MASK				(1 << 21)
+#define SPI_ACTIVE_SDA				(0x3 << 18)
+#define SPI_ACTIVE_SDA_DRIVE_LOW		(0 << 18)
+#define SPI_ACTIVE_SDA_DRIVE_HIGH		(1 << 18)
+#define SPI_ACTIVE_SDA_PULL_LOW			(2 << 18)
+#define SPI_ACTIVE_SDA_PULL_HIGH		(3 << 18)
+
+#define SPI_CS_POL_INVERT			BIT(16)
+#define SPI_TX_EN				BIT(15)
+#define SPI_RX_EN				BIT(14)
+#define SPI_CS_VAL_HIGH				BIT(13)
+#define SPI_CS_VAL_LOW				0x0
+#define SPI_CS_SW				BIT(12)
+#define SPI_CS_HW				0x0
+#define SPI_CS_DELAY_MASK			(7 << 9)
+#define SPI_CS3_EN				BIT(8)
+#define SPI_CS2_EN				BIT(7)
+#define SPI_CS1_EN				BIT(6)
+#define SPI_CS0_EN				BIT(5)
+
+#define SPI_CS_MASK			(SPI_CS3_EN | SPI_CS2_EN |	\
+					SPI_CS1_EN | SPI_CS0_EN)
+#define SPI_BIT_LENGTH(x)		(((x) & 0x1f) << 0)
+
+#define SPI_MODES			(SPI_ACTIVE_SCLK_MASK | SPI_CK_SDA_MASK)
+
+#define SPI_STATUS			0x004
+#define SPI_BSY				BIT(31)
+#define SPI_RDY				BIT(30)
+#define SPI_TXF_FLUSH			BIT(29)
+#define SPI_RXF_FLUSH			BIT(28)
+#define SPI_RX_UNF			BIT(27)
+#define SPI_TX_OVF			BIT(26)
+#define SPI_RXF_EMPTY			BIT(25)
+#define SPI_RXF_FULL			BIT(24)
+#define SPI_TXF_EMPTY			BIT(23)
+#define SPI_TXF_FULL			BIT(22)
+#define SPI_BLK_CNT(count)		(((count) & 0xffff) + 1)
+
+#define SPI_FIFO_ERROR			(SPI_RX_UNF | SPI_TX_OVF)
+#define SPI_FIFO_EMPTY			(SPI_TX_EMPTY | SPI_RX_EMPTY)
+
+#define SPI_RX_CMP			0x8
+#define SPI_DMA_CTL			0x0C
+#define SPI_DMA_EN			BIT(31)
+#define SPI_IE_RXC			BIT(27)
+#define SPI_IE_TXC			BIT(26)
+#define SPI_PACKED			BIT(20)
+#define SPI_RX_TRIG_MASK		(0x3 << 18)
+#define SPI_RX_TRIG_1W			(0x0 << 18)
+#define SPI_RX_TRIG_4W			(0x1 << 18)
+#define SPI_TX_TRIG_MASK		(0x3 << 16)
+#define SPI_TX_TRIG_1W			(0x0 << 16)
+#define SPI_TX_TRIG_4W			(0x1 << 16)
+#define SPI_DMA_BLK_COUNT(count)	(((count) - 1) & 0xFFFF);
+
+#define SPI_TX_FIFO			0x10
+#define SPI_RX_FIFO			0x20
+
+#define DATA_DIR_TX			(1 << 0)
+#define DATA_DIR_RX			(1 << 1)
+
+#define MAX_CHIP_SELECT			4
+#define SPI_FIFO_DEPTH			4
+#define SPI_DMA_TIMEOUT               (msecs_to_jiffies(1000))
+
+struct tegra_sflash_data {
+	struct device				*dev;
+	struct spi_master			*master;
+	spinlock_t				lock;
+
+	struct clk				*clk;
+	void __iomem				*base;
+	unsigned				irq;
+	u32					spi_max_frequency;
+	u32					cur_speed;
+
+	struct spi_device			*cur_spi;
+	unsigned				cur_pos;
+	unsigned				cur_len;
+	unsigned				bytes_per_word;
+	unsigned				cur_direction;
+	unsigned				curr_xfer_words;
+
+	unsigned				cur_rx_pos;
+	unsigned				cur_tx_pos;
+
+	u32					tx_status;
+	u32					rx_status;
+	u32					status_reg;
+
+	u32					def_command_reg;
+	u32					command_reg;
+	u32					dma_control_reg;
+
+	struct completion			xfer_completion;
+	struct spi_transfer			*curr_xfer;
+};
+
+static int tegra_sflash_runtime_suspend(struct device *dev);
+static int tegra_sflash_runtime_resume(struct device *dev);
+
+static inline unsigned long tegra_sflash_readl(struct tegra_sflash_data *tsd,
+		unsigned long reg)
+{
+	return readl(tsd->base + reg);
+}
+
+static inline void tegra_sflash_writel(struct tegra_sflash_data *tsd,
+		unsigned long val, unsigned long reg)
+{
+	writel(val, tsd->base + reg);
+}
+
+static void tegra_sflash_clear_status(struct tegra_sflash_data *tsd)
+{
+	unsigned long val;
+	unsigned long val_write = 0;
+
+	val = tegra_sflash_readl(tsd, SPI_STATUS);
+
+	/* Write 1 to clear status register */
+	val_write = SPI_RDY | SPI_FIFO_ERROR;
+	tegra_sflash_writel(tsd, val_write, SPI_STATUS);
+}
+
+static unsigned tegra_sflash_calculate_curr_xfer_param(
+	struct spi_device *spi, struct tegra_sflash_data *tsd,
+	struct spi_transfer *t)
+{
+	unsigned remain_len = t->len - tsd->cur_pos;
+	unsigned max_word;
+
+	tsd->bytes_per_word = (t->bits_per_word - 1) / 8 + 1;
+	max_word = remain_len / tsd->bytes_per_word;
+	if (max_word > SPI_FIFO_DEPTH)
+		max_word = SPI_FIFO_DEPTH;
+	tsd->curr_xfer_words = max_word;
+	return max_word;
+}
+
+static unsigned tegra_sflash_fill_tx_fifo_from_client_txbuf(
+	struct tegra_sflash_data *tsd, struct spi_transfer *t)
+{
+	unsigned nbytes;
+	unsigned long status;
+	unsigned max_n_32bit = tsd->curr_xfer_words;
+	u8 *tx_buf = (u8 *)t->tx_buf + tsd->cur_tx_pos;
+
+	if (max_n_32bit > SPI_FIFO_DEPTH)
+		max_n_32bit = SPI_FIFO_DEPTH;
+	nbytes = max_n_32bit * tsd->bytes_per_word;
+
+	status = tegra_sflash_readl(tsd, SPI_STATUS);
+	while (!(status & SPI_TXF_FULL)) {
+		int i;
+		unsigned int x = 0;
+
+		for (i = 0; nbytes && (i < tsd->bytes_per_word);
+							i++, nbytes--)
+				x |= ((*tx_buf++) << i*8);
+		tegra_sflash_writel(tsd, x, SPI_TX_FIFO);
+		if (!nbytes)
+			break;
+
+		status = tegra_sflash_readl(tsd, SPI_STATUS);
+	}
+	tsd->cur_tx_pos += max_n_32bit * tsd->bytes_per_word;
+	return max_n_32bit;
+}
+
+static int tegra_sflash_read_rx_fifo_to_client_rxbuf(
+		struct tegra_sflash_data *tsd, struct spi_transfer *t)
+{
+	unsigned long status;
+	unsigned int read_words = 0;
+	u8 *rx_buf = (u8 *)t->rx_buf + tsd->cur_rx_pos;
+
+	status = tegra_sflash_readl(tsd, SPI_STATUS);
+	while (!(status & SPI_RXF_EMPTY)) {
+		int i;
+		unsigned long x;
+
+		x = tegra_sflash_readl(tsd, SPI_RX_FIFO);
+		for (i = 0; (i < tsd->bytes_per_word); i++)
+			*rx_buf++ = (x >> (i*8)) & 0xFF;
+		read_words++;
+		status = tegra_sflash_readl(tsd, SPI_STATUS);
+	}
+	tsd->cur_rx_pos += read_words * tsd->bytes_per_word;
+	return 0;
+}
+
+static int tegra_sflash_start_cpu_based_transfer(
+		struct tegra_sflash_data *tsd, struct spi_transfer *t)
+{
+	unsigned long val = 0;
+	unsigned cur_words;
+
+	if (tsd->cur_direction & DATA_DIR_TX)
+		val |= SPI_IE_TXC;
+
+	if (tsd->cur_direction & DATA_DIR_RX)
+		val |= SPI_IE_RXC;
+
+	tegra_sflash_writel(tsd, val, SPI_DMA_CTL);
+	tsd->dma_control_reg = val;
+
+	if (tsd->cur_direction & DATA_DIR_TX)
+		cur_words = tegra_sflash_fill_tx_fifo_from_client_txbuf(tsd, t);
+	else
+		cur_words = tsd->curr_xfer_words;
+	val |= SPI_DMA_BLK_COUNT(cur_words);
+	tegra_sflash_writel(tsd, val, SPI_DMA_CTL);
+	tsd->dma_control_reg = val;
+	val |= SPI_DMA_EN;
+	tegra_sflash_writel(tsd, val, SPI_DMA_CTL);
+	return 0;
+}
+
+static int tegra_sflash_start_transfer_one(struct spi_device *spi,
+		struct spi_transfer *t, bool is_first_of_msg,
+		bool is_single_xfer)
+{
+	struct tegra_sflash_data *tsd = spi_master_get_devdata(spi->master);
+	u32 speed;
+	unsigned long command;
+
+	speed = t->speed_hz ? t->speed_hz : spi->max_speed_hz;
+	if (!speed)
+		speed = tsd->spi_max_frequency;
+	if (speed != tsd->cur_speed) {
+		clk_set_rate(tsd->clk, speed);
+		tsd->cur_speed = speed;
+	}
+
+	tsd->cur_spi = spi;
+	tsd->cur_pos = 0;
+	tsd->cur_rx_pos = 0;
+	tsd->cur_tx_pos = 0;
+	tsd->curr_xfer = t;
+	tegra_sflash_calculate_curr_xfer_param(spi, tsd, t);
+	if (is_first_of_msg) {
+		command = tsd->def_command_reg;
+		command |= SPI_BIT_LENGTH(t->bits_per_word - 1);
+		command |= SPI_CS_VAL_HIGH;
+
+		command &= ~SPI_MODES;
+		if (spi->mode & SPI_CPHA)
+			command |= SPI_CK_SDA_FALLING;
+
+		if (spi->mode & SPI_CPOL)
+			command |= SPI_ACTIVE_SCLK_DRIVE_HIGH;
+		else
+			command |= SPI_ACTIVE_SCLK_DRIVE_LOW;
+		command |= SPI_CS0_EN << spi->chip_select;
+	} else {
+		command = tsd->command_reg;
+		command &= ~SPI_BIT_LENGTH(~0);
+		command |= SPI_BIT_LENGTH(t->bits_per_word - 1);
+		command &= ~(SPI_RX_EN | SPI_TX_EN);
+	}
+
+	tsd->cur_direction = 0;
+	if (t->rx_buf) {
+		command |= SPI_RX_EN;
+		tsd->cur_direction |= DATA_DIR_RX;
+	}
+	if (t->tx_buf) {
+		command |= SPI_TX_EN;
+		tsd->cur_direction |= DATA_DIR_TX;
+	}
+	tegra_sflash_writel(tsd, command, SPI_COMMAND);
+	tsd->command_reg = command;
+
+	return  tegra_sflash_start_cpu_based_transfer(tsd, t);
+}
+
+static int tegra_sflash_transfer_one_message(struct spi_master *master,
+			struct spi_message *msg)
+{
+	bool is_first_msg = true;
+	int single_xfer;
+	struct tegra_sflash_data *tsd = spi_master_get_devdata(master);
+	struct spi_transfer *xfer;
+	struct spi_device *spi = msg->spi;
+	int ret;
+
+	ret = pm_runtime_get_sync(tsd->dev);
+	if (ret < 0) {
+		dev_err(tsd->dev, "pm_runtime_get() failed, err = %d\n", ret);
+		return ret;
+	}
+
+	msg->status = 0;
+	msg->actual_length = 0;
+	single_xfer = list_is_singular(&msg->transfers);
+	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+		INIT_COMPLETION(tsd->xfer_completion);
+		ret = tegra_sflash_start_transfer_one(spi, xfer,
+					is_first_msg, single_xfer);
+		if (ret < 0) {
+			dev_err(tsd->dev,
+				"spi can not start transfer, err %d\n", ret);
+			goto exit;
+		}
+		is_first_msg = false;
+		ret = wait_for_completion_timeout(&tsd->xfer_completion,
+						SPI_DMA_TIMEOUT);
+		if (WARN_ON(ret == 0)) {
+			dev_err(tsd->dev,
+				"spi trasfer timeout, err %d\n", ret);
+			ret = -EIO;
+			goto exit;
+		}
+
+		if (tsd->tx_status ||  tsd->rx_status) {
+			dev_err(tsd->dev, "Error in Transfer\n");
+			ret = -EIO;
+			goto exit;
+		}
+		msg->actual_length += xfer->len;
+		if (xfer->cs_change && xfer->delay_usecs) {
+			tegra_sflash_writel(tsd, tsd->def_command_reg,
+					SPI_COMMAND);
+			udelay(xfer->delay_usecs);
+		}
+	}
+	ret = 0;
+exit:
+	tegra_sflash_writel(tsd, tsd->def_command_reg, SPI_COMMAND);
+	msg->status = ret;
+	spi_finalize_current_message(master);
+	pm_runtime_put(tsd->dev);
+	return ret;
+}
+
+static irqreturn_t handle_cpu_based_xfer(struct tegra_sflash_data *tsd)
+{
+	struct spi_transfer *t = tsd->curr_xfer;
+	unsigned long flags;
+
+	spin_lock_irqsave(&tsd->lock, flags);
+	if (tsd->tx_status ||  tsd->rx_status ||
+				(tsd->status_reg & SPI_BSY)) {
+		dev_err(tsd->dev,
+			"CpuXfer ERROR bit set 0x%x\n", tsd->status_reg);
+		dev_err(tsd->dev,
+			"CpuXfer 0x%08x:0x%08x\n", tsd->command_reg,
+				tsd->dma_control_reg);
+		tegra_periph_reset_assert(tsd->clk);
+		udelay(2);
+		tegra_periph_reset_deassert(tsd->clk);
+		complete(&tsd->xfer_completion);
+		goto exit;
+	}
+
+	if (tsd->cur_direction & DATA_DIR_RX)
+		tegra_sflash_read_rx_fifo_to_client_rxbuf(tsd, t);
+
+	if (tsd->cur_direction & DATA_DIR_TX)
+		tsd->cur_pos = tsd->cur_tx_pos;
+	else
+		tsd->cur_pos = tsd->cur_rx_pos;
+
+	if (tsd->cur_pos == t->len) {
+		complete(&tsd->xfer_completion);
+		goto exit;
+	}
+
+	tegra_sflash_calculate_curr_xfer_param(tsd->cur_spi, tsd, t);
+	tegra_sflash_start_cpu_based_transfer(tsd, t);
+exit:
+	spin_unlock_irqrestore(&tsd->lock, flags);
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t tegra_sflash_isr(int irq, void *context_data)
+{
+	struct tegra_sflash_data *tsd = context_data;
+
+	tsd->status_reg = tegra_sflash_readl(tsd, SPI_STATUS);
+	if (tsd->cur_direction & DATA_DIR_TX)
+		tsd->tx_status = tsd->status_reg & SPI_TX_OVF;
+
+	if (tsd->cur_direction & DATA_DIR_RX)
+		tsd->rx_status = tsd->status_reg & SPI_RX_UNF;
+	tegra_sflash_clear_status(tsd);
+
+	return handle_cpu_based_xfer(tsd);
+}
+
+static struct tegra_spi_platform_data *tegra_sflash_parse_dt(
+		struct platform_device *pdev)
+{
+	struct tegra_spi_platform_data *pdata;
+	const unsigned int *prop;
+	struct device_node *np = pdev->dev.of_node;
+
+	pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
+	if (!pdata) {
+		dev_err(&pdev->dev, "Memory alloc for pdata failed\n");
+		return NULL;
+	}
+
+	prop = of_get_property(np, "spi-max-frequency", NULL);
+	if (prop)
+		pdata->spi_max_frequency = be32_to_cpup(prop);
+
+	return pdata;
+}
+
+static struct of_device_id tegra_sflash_of_match[] __devinitconst = {
+	{ .compatible = "nvidia,tegra20-sflash", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, tegra_sflash_of_match);
+
+static int __devinit tegra_sflash_probe(struct platform_device *pdev)
+{
+	struct spi_master	*master;
+	struct tegra_sflash_data	*tsd;
+	struct resource		*r;
+	struct tegra_spi_platform_data *pdata = pdev->dev.platform_data;
+	int ret;
+	const struct of_device_id *match;
+
+	match = of_match_device(of_match_ptr(tegra_sflash_of_match),
+					&pdev->dev);
+	if (!match) {
+		dev_err(&pdev->dev, "Error: No device match found\n");
+		return -ENODEV;
+	}
+
+	if (!pdata && pdev->dev.of_node)
+		pdata = tegra_sflash_parse_dt(pdev);
+
+	if (!pdata) {
+		dev_err(&pdev->dev, "No platform data, exiting\n");
+		return -ENODEV;
+	}
+
+	if (!pdata->spi_max_frequency)
+		pdata->spi_max_frequency = 25000000; /* 25MHz */
+
+	master = spi_alloc_master(&pdev->dev, sizeof(*tsd));
+	if (!master) {
+		dev_err(&pdev->dev, "master allocation failed\n");
+		return -ENOMEM;
+	}
+
+	/* the spi->mode bits understood by this driver: */
+	master->mode_bits = SPI_CPOL | SPI_CPHA;
+	master->transfer_one_message = tegra_sflash_transfer_one_message;
+	master->num_chipselect = MAX_CHIP_SELECT;
+	master->bus_num = -1;
+
+	dev_set_drvdata(&pdev->dev, master);
+	tsd = spi_master_get_devdata(master);
+	tsd->master = master;
+	tsd->dev = &pdev->dev;
+	spin_lock_init(&tsd->lock);
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!r) {
+		dev_err(&pdev->dev, "No IO memory resource\n");
+		ret = -ENODEV;
+		goto exit_free_master;
+	}
+	tsd->base = devm_request_and_ioremap(&pdev->dev, r);
+	if (!tsd->base) {
+		dev_err(&pdev->dev,
+			"Cannot request memregion/iomap dma address\n");
+		ret = -EADDRNOTAVAIL;
+		goto exit_free_master;
+	}
+
+	tsd->irq = platform_get_irq(pdev, 0);
+	ret = request_irq(tsd->irq, tegra_sflash_isr, 0,
+			dev_name(&pdev->dev), tsd);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Failed to register ISR for IRQ %d\n",
+					tsd->irq);
+		goto exit_free_master;
+	}
+
+	tsd->clk = devm_clk_get(&pdev->dev, "spi");
+	if (IS_ERR(tsd->clk)) {
+		dev_err(&pdev->dev, "can not get clock\n");
+		ret = PTR_ERR(tsd->clk);
+		goto exit_free_irq;
+	}
+
+
+	tsd->spi_max_frequency = pdata->spi_max_frequency;
+
+	init_completion(&tsd->xfer_completion);
+
+	pm_runtime_enable(&pdev->dev);
+	if (!pm_runtime_enabled(&pdev->dev)) {
+		ret = tegra_sflash_runtime_resume(&pdev->dev);
+		if (ret)
+			goto exit_pm_disable;
+	}
+
+	ret = pm_runtime_get_sync(&pdev->dev);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "pm runtime get failed, e = %d\n", ret);
+		goto exit_pm_disable;
+	}
+
+	/* Reset controller */
+	tegra_periph_reset_assert(tsd->clk);
+	udelay(2);
+	tegra_periph_reset_deassert(tsd->clk);
+
+	tsd->def_command_reg  = SPI_M_S | SPI_CS_SW;
+	tegra_sflash_writel(tsd, tsd->def_command_reg, SPI_COMMAND);
+	pm_runtime_put(&pdev->dev);
+
+	master->dev.of_node = pdev->dev.of_node;
+	ret = spi_register_master(master);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "can not register to master err %d\n", ret);
+		goto exit_pm_disable;
+	}
+	return ret;
+
+exit_pm_disable:
+	pm_runtime_disable(&pdev->dev);
+	if (!pm_runtime_status_suspended(&pdev->dev))
+		tegra_sflash_runtime_suspend(&pdev->dev);
+exit_free_irq:
+	free_irq(tsd->irq, tsd);
+exit_free_master:
+	spi_master_put(master);
+	return ret;
+}
+
+static int __devexit tegra_sflash_remove(struct platform_device *pdev)
+{
+	struct spi_master *master = dev_get_drvdata(&pdev->dev);
+	struct tegra_sflash_data	*tsd = spi_master_get_devdata(master);
+
+	free_irq(tsd->irq, tsd);
+	spi_unregister_master(master);
+
+	pm_runtime_disable(&pdev->dev);
+	if (!pm_runtime_status_suspended(&pdev->dev))
+		tegra_sflash_runtime_suspend(&pdev->dev);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int tegra_sflash_suspend(struct device *dev)
+{
+	struct spi_master *master = dev_get_drvdata(dev);
+
+	return spi_master_suspend(master);
+}
+
+static int tegra_sflash_resume(struct device *dev)
+{
+	struct spi_master *master = dev_get_drvdata(dev);
+	struct tegra_sflash_data *tsd = spi_master_get_devdata(master);
+	int ret;
+
+	ret = pm_runtime_get_sync(dev);
+	if (ret < 0) {
+		dev_err(dev, "pm runtime failed, e = %d\n", ret);
+		return ret;
+	}
+	tegra_sflash_writel(tsd, tsd->command_reg, SPI_COMMAND);
+	pm_runtime_put(dev);
+
+	return spi_master_resume(master);
+}
+#endif
+
+static int tegra_sflash_runtime_suspend(struct device *dev)
+{
+	struct spi_master *master = dev_get_drvdata(dev);
+	struct tegra_sflash_data *tsd = spi_master_get_devdata(master);
+
+	/* Flush all write which are in PPSB queue by reading back */
+	tegra_sflash_readl(tsd, SPI_COMMAND);
+
+	clk_disable_unprepare(tsd->clk);
+	return 0;
+}
+
+static int tegra_sflash_runtime_resume(struct device *dev)
+{
+	struct spi_master *master = dev_get_drvdata(dev);
+	struct tegra_sflash_data *tsd = spi_master_get_devdata(master);
+	int ret;
+
+	ret = clk_prepare_enable(tsd->clk);
+	if (ret < 0) {
+		dev_err(tsd->dev, "clk_prepare failed: %d\n", ret);
+		return ret;
+	}
+	return 0;
+}
+
+static const struct dev_pm_ops slink_pm_ops = {
+	SET_RUNTIME_PM_OPS(tegra_sflash_runtime_suspend,
+		tegra_sflash_runtime_resume, NULL)
+	SET_SYSTEM_SLEEP_PM_OPS(tegra_sflash_suspend, tegra_sflash_resume)
+};
+static struct platform_driver tegra_sflash_driver = {
+	.driver = {
+		.name		= "spi-tegra-sflash",
+		.owner		= THIS_MODULE,
+		.pm		= &slink_pm_ops,
+		.of_match_table	= of_match_ptr(tegra_sflash_of_match),
+	},
+	.probe =	tegra_sflash_probe,
+	.remove =	__devexit_p(tegra_sflash_remove),
+};
+module_platform_driver(tegra_sflash_driver);
+
+MODULE_ALIAS("platform:spi-tegra-sflash");
+MODULE_DESCRIPTION("NVIDIA Tegra20 Serial Flash Controller Driver");
+MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
+MODULE_LICENSE("GPL v2");
-- 
1.7.1.1

Re: [PATCH] spi: tegra: add spi driver for sflash controller

[Stephen Warren]

On 11/12/2012 10:00 PM, Laxman Dewangan wrote:
> Nvidia's Tegra20 have the SPI (SFLASH) controller to
> interface with spi flash device which is used for system
> boot. Add the spi driver for this controller.

> diff --git a/drivers/spi/spi-tegra20-sflash.c b/drivers/spi/spi-tegra20-sflash.c

> +static void tegra_sflash_clear_status(struct tegra_sflash_data *tsd)
> +{
> +	unsigned long val;
> +	unsigned long val_write = 0;
> +
> +	val = tegra_sflash_readl(tsd, SPI_STATUS);

Why the read of the unused value. Is this to flush earlier bus
transactions, or just left over? If for bus flushing, a comment would be
useful.

> +	/* Write 1 to clear status register */
> +	val_write = SPI_RDY | SPI_FIFO_ERROR;
> +	tegra_sflash_writel(tsd, val_write, SPI_STATUS);
> +}

> +static irqreturn_t handle_cpu_based_xfer(struct tegra_sflash_data *tsd)
> +{
> +	struct spi_transfer *t = tsd->curr_xfer;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&tsd->lock, flags);
> +	if (tsd->tx_status ||  tsd->rx_status ||

Nit: double-space after first || above.

> +static struct tegra_spi_platform_data *tegra_sflash_parse_dt(
> +		struct platform_device *pdev)

> +	prop = of_get_property(np, "spi-max-frequency", NULL);
> +	if (prop)
> +		pdata->spi_max_frequency = be32_to_cpup(prop);

Perhaps use of_property_read_u32()?

> +static int __devinit tegra_sflash_probe(struct platform_device *pdev)

> +	tsd->clk = devm_clk_get(&pdev->dev, "spi");
> +	if (IS_ERR(tsd->clk)) {
> +		dev_err(&pdev->dev, "can not get clock\n");
> +		ret = PTR_ERR(tsd->clk);
> +		goto exit_free_irq;
> +	}
> +
> +
> +	tsd->spi_max_frequency = pdata->spi_max_frequency;

Nit: Double blank-line there.

> +static int tegra_sflash_resume(struct device *dev)
> +{
> +	struct spi_master *master = dev_get_drvdata(dev);
> +	struct tegra_sflash_data *tsd = spi_master_get_devdata(master);
> +	int ret;
> +
> +	ret = pm_runtime_get_sync(dev);
> +	if (ret < 0) {
> +		dev_err(dev, "pm runtime failed, e = %d\n", ret);
> +		return ret;
> +	}
> +	tegra_sflash_writel(tsd, tsd->command_reg, SPI_COMMAND);
> +	pm_runtime_put(dev);

Can we avoid this whole function simply by programming SPI_COMMAND at
the start of each transaction? That seems simpler. I assume that
shouldn't e.g. leave any chip-selects in some bad state, or at least if
it does, that shouldn't be a problem, because before the driver probes()
at kernel boot, SPI_COMMAND won't have been programmed either.

Aside from that,

Acked-by: Stephen Warren <swarren@nvidia.com>
Tested-by: Stephen Warren <swarren@nvidia.com>

Thanks.

Re: [PATCH] spi: tegra: add spi driver for sflash controller

[Laxman Dewangan]

On Tuesday 13 November 2012 10:55 PM, Stephen Warren wrote:
> On 11/12/2012 10:00 PM, Laxman Dewangan wrote:
>
>> +static int tegra_sflash_resume(struct device *dev)
>> +{
>> +	struct spi_master *master = dev_get_drvdata(dev);
>> +	struct tegra_sflash_data *tsd = spi_master_get_devdata(master);
>> +	int ret;
>> +
>> +	ret = pm_runtime_get_sync(dev);
>> +	if (ret<  0) {
>> +		dev_err(dev, "pm runtime failed, e = %d\n", ret);
>> +		return ret;
>> +	}
>> +	tegra_sflash_writel(tsd, tsd->command_reg, SPI_COMMAND);
>> +	pm_runtime_put(dev);
> Can we avoid this whole function simply by programming SPI_COMMAND at
> the start of each transaction? That seems simpler. I assume that
> shouldn't e.g. leave any chip-selects in some bad state, or at least if
> it does, that shouldn't be a problem, because before the driver probes()
> at kernel boot, SPI_COMMAND won't have been programmed either.
>
> Aside from that,

I am not sure about the side effect of moving this to transfer but I can 
suspect:
When client driver is active, it need the proper state of CS. If we move 
this to transfer then probbaly CS is not in proper state until client 
calls the transfer function and this is not correct. The CS should be 
inactive state for all devices in non-transfer states.

> Acked-by: Stephen Warren<swarren@nvidia.com>
> Tested-by: Stephen Warren<swarren@nvidia.com>

Thanks for testing. I will respin patch V2 for taking care of above 
comments.