[v2,1/4] spi: Add new driver for STMicroelectronics' SPI Controller

This patch adds support for the SPI portion of ST's SSC device.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 drivers/spi/Kconfig       |   7 +
 drivers/spi/Makefile      |   1 +
 drivers/spi/spi-st-ssc4.c | 509 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 517 insertions(+)
 create mode 100644 drivers/spi/spi-st-ssc4.c

> Some minors remarks below

Thanks Patrice.  I will fix these up in v3.

Mark,

  Would you mind casting your eye over this submission prior to
the v3 please?

> On 12/02/2014 04:40 PM, Lee Jones wrote:
> >This patch adds support for the SPI portion of ST's SSC device.
> >
> >Signed-off-by: Lee Jones <lee.jones@linaro.org>
> >---
> >  drivers/spi/Kconfig       |   7 +
> >  drivers/spi/Makefile      |   1 +
> >  drivers/spi/spi-st-ssc4.c | 509 ++++++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 517 insertions(+)
> >  create mode 100644 drivers/spi/spi-st-ssc4.c
> >
> >diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
> >index 84e7c9e..bd0a10f 100644
> >--- a/drivers/spi/Kconfig
> >+++ b/drivers/spi/Kconfig
> >@@ -488,6 +488,13 @@ config SPI_SIRF
> >  	help
> >  	  SPI driver for CSR SiRFprimaII SoCs
> >+config SPI_ST_SSC4
> >+	tristate "STMicroelectronics SPI SSC-based driver"
> >+	depends on ARCH_STI || COMPILE_TEST
> >+	help
> >+	  STMicroelectronics SoCs support for SPI. If you say yes to
> >+	  this option, support will be included for the SSC driven SPI.
> >+
> >  config SPI_SUN4I
> >  	tristate "Allwinner A10 SoCs SPI controller"
> >  	depends on ARCH_SUNXI || COMPILE_TEST
> >diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
> >index 78f24ca..c38e28c 100644
> >--- a/drivers/spi/Makefile
> >+++ b/drivers/spi/Makefile
> >@@ -74,6 +74,7 @@ obj-$(CONFIG_SPI_SH_HSPI)		+= spi-sh-hspi.o
> >  obj-$(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-$(CONFIG_SPI_ST_SSC4)		+= spi-st-ssc4.o
> >  obj-$(CONFIG_SPI_SUN4I)			+= spi-sun4i.o
> >  obj-$(CONFIG_SPI_SUN6I)			+= spi-sun6i.o
> >  obj-$(CONFIG_SPI_TEGRA114)		+= spi-tegra114.o
> >diff --git a/drivers/spi/spi-st-ssc4.c b/drivers/spi/spi-st-ssc4.c
> >new file mode 100644
> >index 0000000..566d86c
> >--- /dev/null
> >+++ b/drivers/spi/spi-st-ssc4.c
> >@@ -0,0 +1,509 @@
> >+/*
> >+ *  Copyright (c) 2008-2014 STMicroelectronics Limited
> >+ *
> >+ *  Author: Angus Clark <Angus.Clark@st.com>
> >+ *          Patrice Chotard <patrice.chotard@st.com>
> >+ *          Lee Jones <lee.jones@linaro.org>
> >+ *
> >+ *  SPI master mode controller driver, used in STMicroelectronics devices.
> >+ *
> >+ *  May be copied or modified under the terms of the GNU General Public
> >+ *  License Version 2.0 only.  See linux/COPYING for more information.
> >+ */
> >+
> >+#include <linux/clk.h>
> >+#include <linux/delay.h>
> >+#include <linux/interrupt.h>
> >+#include <linux/io.h>
> >+#include <linux/module.h>
> >+#include <linux/platform_device.h>
> >+#include <linux/of.h>
> >+#include <linux/of_gpio.h>
> >+#include <linux/of_irq.h>
> >+#include <linux/pm_runtime.h>
> >+#include <linux/spi/spi.h>
> >+#include <linux/spi/spi_bitbang.h>
> >+
> >+/* SSC registers */
> >+#define SSC_BRG				0x000
> >+#define SSC_TBUF			0x004
> >+#define SSC_RBUF			0x008
> >+#define SSC_CTL				0x00C
> >+#define SSC_IEN				0x010
> >+#define SSC_I2C				0x018
> >+
> >+/* SSC Control */
> >+#define SSC_CTL_DATA_WIDTH_9		0x8
> >+#define SSC_CTL_DATA_WIDTH_MSK		0xf
> >+#define SSC_CTL_BM			0xf
> >+#define SSC_CTL_HB			BIT(4)
> >+#define SSC_CTL_PH			BIT(5)
> >+#define SSC_CTL_PO			BIT(6)
> >+#define SSC_CTL_SR			BIT(7)
> >+#define SSC_CTL_MS			BIT(8)
> >+#define SSC_CTL_EN			BIT(9)
> >+#define SSC_CTL_LPB			BIT(10)
> >+#define SSC_CTL_EN_TX_FIFO		BIT(11)
> >+#define SSC_CTL_EN_RX_FIFO		BIT(12)
> >+#define SSC_CTL_EN_CLST_RX		BIT(13)
> >+
> >+/* SSC Interrupt Enable */
> >+#define SSC_IEN_TEEN			BIT(2)
> >+
> >+#define FIFO_SIZE			8
> >+
> >+struct spi_st {
> >+	/* SSC SPI Controller */
> >+	void __iomem		*base;
> >+	struct clk		*clk;
> >+	struct device		*dev;
> >+
> >+	/* SSC SPI current transaction */
> >+	const u8		*tx_ptr;
> >+	u8			*rx_ptr;
> >+	u16			bytes_per_word;
> >+	unsigned int		words_remaining;
> >+	unsigned int		baud;
> >+	struct completion	done;
> >+};
> >+
> >+static int spi_st_clk_enable(struct spi_st *spi_st)
> >+{
> >+	/*
> >+	 * Current platforms use one of the core clocks for SPI and I2C.
> >+	 * If we attempt to disable the clock, the system will hang.
> >+	 *
> >+	 * TODO: Remove this when platform supports power domains.
> >+	 */
> >+	return 0;
> >+
> >+	return clk_prepare_enable(spi_st->clk);
> >+}
> >+
> >+static void spi_st_clk_disable(struct spi_st *spi_st)
> >+{
> >+	/*
> >+	 * Current platforms use one of the core clocks for SPI and I2C.
> >+	 * If we attempt to disable the clock, the system will hang.
> >+	 *
> >+	 * TODO: Remove this when platform supports power domains.
> >+	 */
> >+	return;
> >+
> >+	clk_disable_unprepare(spi_st->clk);
> >+}
> >+
> >+/* Load the TX FIFO */
> >+static void ssc_write_tx_fifo(struct spi_st *spi_st)
> >+{
> >+	unsigned int count, i;
> >+	uint32_t word = 0;
> >+
> >+	if (spi_st->words_remaining > FIFO_SIZE)
> >+		count = FIFO_SIZE;
> >+	else
> >+		count = spi_st->words_remaining;
> >+
> >+	for (i = 0; i < count; i++) {
> >+		if (spi_st->tx_ptr) {
> >+			if (spi_st->bytes_per_word == 1) {
> >+				word = *spi_st->tx_ptr++;
> >+			} else {
> >+				word = *spi_st->tx_ptr++;
> >+				word = *spi_st->tx_ptr++ | (word << 8);
> >+			}
> >+		}
> >+		writel_relaxed(word, spi_st->base + SSC_TBUF);
> >+	}
> >+}
> >+
> >+/* Read the RX FIFO */
> >+static void ssc_read_rx_fifo(struct spi_st *spi_st)
> >+{
> >+	unsigned int count, i;
> >+	uint32_t word = 0;
> >+
> >+	if (spi_st->words_remaining > FIFO_SIZE)
> >+		count = FIFO_SIZE;
> >+	else
> >+		count = spi_st->words_remaining;
> >+
> >+	for (i = 0; i < count; i++) {
> >+		word = readl_relaxed(spi_st->base + SSC_RBUF);
> >+
> >+		if (spi_st->rx_ptr) {
> >+			if (spi_st->bytes_per_word == 1) {
> >+				*spi_st->rx_ptr++ = (uint8_t)word;
> >+			} else {
> >+				*spi_st->rx_ptr++ = (word >> 8);
> >+				*spi_st->rx_ptr++ = word & 0xff;
> >+			}
> >+		}
> >+	}
> >+	spi_st->words_remaining -= count;
> >+}
> >+
> >+static int spi_st_transfer_one(struct spi_master *master,
> >+			       struct spi_device *spi, struct spi_transfer *t)
> >+{
> >+	struct spi_st *spi_st = spi_master_get_devdata(master);
> >+	uint32_t ctl = 0;
> >+
> >+	/* Setup transfer */
> >+	spi_st->tx_ptr = t->tx_buf;
> >+	spi_st->rx_ptr = t->rx_buf;
> >+
> >+	if (spi->bits_per_word > 8) {
> >+		/*
> >+		 * Anything greater than 8 bits-per-word requires 2
> >+		 * bytes-per-word in the RX/TX buffers
> >+		 */
> >+		spi_st->bytes_per_word = 2;
> >+		spi_st->words_remaining = t->len / 2;
> >+
> >+	} else if (spi->bits_per_word == 8 && !(t->len & 0x1)) {
> >+		/*
> >+		 * If transfer is even-length, and 8 bits-per-word, then
> >+		 * implement as half-length 16 bits-per-word transfer
> >+		 */
> >+		spi_st->bytes_per_word = 2;
> >+		spi_st->words_remaining = t->len/2;
> 
> add space around "/"
> 
> >+
> >+		/* Set SSC_CTL to 16 bits-per-word */
> >+		ctl = readl_relaxed(spi_st->base + SSC_CTL);
> >+		writel_relaxed((ctl | 0xf), spi_st->base + SSC_CTL);
> >+
> >+		readl_relaxed(spi_st->base + SSC_RBUF);
> >+
> >+	} else {
> >+		spi_st->bytes_per_word = 1;
> >+		spi_st->words_remaining = t->len;
> >+	}
> >+
> >+	reinit_completion(&spi_st->done);
> >+
> >+	/* Start transfer by writing to the TX FIFO */
> >+	ssc_write_tx_fifo(spi_st);
> >+	writel_relaxed(SSC_IEN_TEEN, spi_st->base + SSC_IEN);
> >+
> >+	/* Wait for transfer to complete */
> >+	wait_for_completion(&spi_st->done);
> >+
> >+	/* Restore SSC_CTL if necessary */
> >+	if (ctl)
> >+		writel_relaxed(ctl, spi_st->base + SSC_CTL);
> >+
> >+	spi_finalize_current_transfer(spi->master);
> >+
> >+	return t->len;
> >+}
> >+
> >+static void spi_st_cleanup(struct spi_device *spi)
> >+{
> >+	int cs = spi->cs_gpio;
> >+
> >+	if (gpio_is_valid(cs))
> >+		devm_gpio_free(&spi->dev, cs);
> >+}
> >+
> >+/* the spi->mode bits understood by this driver: */
> >+#define MODEBITS  (SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST | SPI_LOOP | SPI_CS_HIGH)
> >+static int spi_st_setup(struct spi_device *spi)
> >+{
> >+	struct spi_st *spi_st = spi_master_get_devdata(spi->master);
> >+	u32 spi_st_clk, sscbrg, var;
> >+	u32 hz = spi->max_speed_hz;
> >+	int cs = spi->cs_gpio;
> >+	int ret;
> >+
> >+	if (spi->mode & ~MODEBITS) {
> >+		dev_err(&spi->dev, "unsupported mode bits 0x%x\n",
> >+			spi->mode & ~MODEBITS);
> >+		return -EINVAL;
> >+	}
> >+
> >+	if (!hz)  {
> >+		dev_err(&spi->dev, "max_speed_hz unspecified\n");
> >+		return -EINVAL;
> >+	}
> >+
> >+	if (!gpio_is_valid(cs)) {
> >+		dev_err(&spi->dev, "%d is not a valid gpio\n", cs);
> >+		return -EINVAL;
> >+	}
> >+
> >+	if (devm_gpio_request(&spi->dev, cs, dev_name(&spi->dev))) {
> >+		dev_err(&spi->dev, "could not request gpio:%d\n", cs);
> >+		return -EINVAL;
> >+	}
> >+
> >+	ret = gpio_direction_output(cs, spi->mode & SPI_CS_HIGH);
> >+	if (ret)
> >+		return ret;
> >+
> >+	spi_st_clk = clk_get_rate(spi_st->clk);
> >+
> >+	/* Set SSC_BRF */
> >+	sscbrg = spi_st_clk / (2 * hz);
> >+	if (sscbrg < 0x07 || sscbrg > (0x1 << 16)) {
> 
> (0x1 << 16) can be replaced by BIT(16)
> 
> 
> 
> >+		dev_err(&spi->dev,
> >+			"baudrate %d outside valid range %d\n", sscbrg, hz);
> >+		return -EINVAL;
> >+	}
> >+
> >+	spi_st->baud = spi_st_clk / (2 * sscbrg);
> >+	if (sscbrg == (0x1 << 16)) /* 16-bit counter wraps */
> 
> ditto
> 
> >+		sscbrg = 0x0;
> >+
> >+	writel_relaxed(sscbrg, spi_st->base + SSC_BRG);
> >+
> >+	dev_dbg(&spi->dev,
> >+		"setting baudrate:target= %u hz, actual= %u hz, sscbrg= %u\n",
> >+		hz, spi_st->baud, sscbrg);
> >+
> >+	 /* Set SSC_CTL and enable SSC */
> >+	 var = readl_relaxed(spi_st->base + SSC_CTL);
> >+	 var |= SSC_CTL_MS;
> >+
> >+	 if (spi->mode & SPI_CPOL)
> >+		var |= SSC_CTL_PO;
> >+	 else
> >+		var &= ~SSC_CTL_PO;
> >+
> >+	 if (spi->mode & SPI_CPHA)
> >+		var |= SSC_CTL_PH;
> >+	 else
> >+		var &= ~SSC_CTL_PH;
> >+
> >+	 if ((spi->mode & SPI_LSB_FIRST) == 0)
> >+		var |= SSC_CTL_HB;
> >+	 else
> >+		var &= ~SSC_CTL_HB;
> >+
> >+	 if (spi->mode & SPI_LOOP)
> >+		var |= SSC_CTL_LPB;
> >+	 else
> >+		var &= ~SSC_CTL_LPB;
> >+
> >+	 var &= ~SSC_CTL_DATA_WIDTH_MSK;
> >+	 var |= (spi->bits_per_word - 1);
> >+
> >+	 var |= SSC_CTL_EN_TX_FIFO | SSC_CTL_EN_RX_FIFO;
> >+	 var |= SSC_CTL_EN;
> >+
> >+	 writel_relaxed(var, spi_st->base + SSC_CTL);
> >+
> >+	 /* Clear the status register */
> >+	 readl_relaxed(spi_st->base + SSC_RBUF);
> >+
> >+	 return 0;
> >+}
> >+
> >+/* Interrupt fired when TX shift register becomes empty */
> >+static irqreturn_t spi_st_irq(int irq, void *dev_id)
> >+{
> >+	struct spi_st *spi_st = (struct spi_st *)dev_id;
> >+
> >+	/* Read RX FIFO */
> >+	ssc_read_rx_fifo(spi_st);
> >+
> >+	/* Fill TX FIFO */
> >+	if (spi_st->words_remaining) {
> >+		ssc_write_tx_fifo(spi_st);
> >+	} else {
> >+		/* TX/RX complete */
> >+		writel_relaxed(0x0, spi_st->base + SSC_IEN);
> >+		/*
> >+		 * read SSC_IEN to ensure that this bit is set
> >+		 * before re-enabling interrupt
> >+		 */
> >+		readl(spi_st->base + SSC_IEN);
> >+		complete(&spi_st->done);
> >+	}
> >+
> >+	return IRQ_HANDLED;
> >+}
> >+
> >+static int spi_st_probe(struct platform_device *pdev)
> >+{
> >+	struct device_node *np = pdev->dev.of_node;
> >+	struct spi_master *master;
> >+	struct resource *res;
> >+	struct spi_st *spi_st;
> >+	int irq, ret = 0;
> >+	u32 var;
> >+
> >+	master = spi_alloc_master(&pdev->dev, sizeof(*spi_st));
> >+	if (!master)
> >+		return -ENOMEM;
> >+
> >+	master->dev.of_node		= np;
> >+	master->mode_bits		= MODEBITS;
> >+	master->setup			= spi_st_setup;
> >+	master->cleanup			= spi_st_cleanup;
> >+	master->transfer_one		= spi_st_transfer_one;
> >+	master->bits_per_word_mask	= SPI_BPW_MASK(8) | SPI_BPW_MASK(16);
> >+	master->auto_runtime_pm		= true;
> >+	master->bus_num			= pdev->id;
> >+	spi_st				= spi_master_get_devdata(master);
> >+
> >+	spi_st->clk = devm_clk_get(&pdev->dev, "ssc");
> >+	if (IS_ERR(spi_st->clk)) {
> >+		dev_err(&pdev->dev, "Unable to request clock\n");
> >+		return PTR_ERR(spi_st->clk);
> >+	}
> >+
> >+	ret = spi_st_clk_enable(spi_st);
> >+	if (ret)
> >+		return ret;
> >+
> >+	init_completion(&spi_st->done);
> >+
> >+	/* Get resources */
> >+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> >+	spi_st->base = devm_ioremap_resource(&pdev->dev, res);
> >+	if (IS_ERR(spi_st->base)) {
> >+		ret = PTR_ERR(spi_st->base);
> >+		goto clk_disable;
> >+	}
> >+
> >+	/* Disable I2C and Reset SSC */
> >+	writel_relaxed(0x0, spi_st->base + SSC_I2C);
> >+	var = readw_relaxed(spi_st->base + SSC_CTL);
> >+	var |= SSC_CTL_SR;
> >+	writel_relaxed(var, spi_st->base + SSC_CTL);
> >+
> >+	udelay(1);
> >+	var = readl_relaxed(spi_st->base + SSC_CTL);
> >+	var &= ~SSC_CTL_SR;
> >+	writel_relaxed(var, spi_st->base + SSC_CTL);
> >+
> >+	/* Set SSC into slave mode before reconfiguring PIO pins */
> >+	var = readl_relaxed(spi_st->base + SSC_CTL);
> >+	var &= ~SSC_CTL_MS;
> >+	writel_relaxed(var, spi_st->base + SSC_CTL);
> >+
> >+	irq = irq_of_parse_and_map(np, 0);
> >+	if (!irq) {
> >+		dev_err(&pdev->dev, "IRQ missing or invalid\n");
> >+		ret = -EINVAL;
> >+		goto clk_disable;
> >+	}
> >+
> >+	ret = devm_request_irq(&pdev->dev, irq, spi_st_irq, 0,
> >+			       pdev->name, spi_st);
> >+	if (ret) {
> >+		dev_err(&pdev->dev, "Failed to request irq %d\n", irq);
> >+		goto clk_disable;
> >+	}
> >+
> >+	/* by default the device is on */
> >+	pm_runtime_set_active(&pdev->dev);
> >+	pm_runtime_enable(&pdev->dev);
> >+
> >+	platform_set_drvdata(pdev, master);
> >+
> >+	ret = devm_spi_register_master(&pdev->dev, master);
> >+	if (ret) {
> >+		dev_err(&pdev->dev, "Failed to register master\n");
> >+		goto clk_disable;
> >+	}
> >+
> >+	return 0;
> >+
> >+clk_disable:
> >+	spi_st_clk_disable(spi_st);
> >+
> >+	return ret;
> >+}
> >+
> >+static int spi_st_remove(struct platform_device *pdev)
> >+{
> >+	struct spi_master *master = platform_get_drvdata(pdev);
> >+	struct spi_st *spi_st = spi_master_get_devdata(master);
> >+
> >+	spi_st_clk_disable(spi_st);
> >+
> >+	pinctrl_pm_select_sleep_state(&pdev->dev);
> >+
> >+	return 0;
> >+}
> >+
> >+#ifdef CONFIG_PM
> >+static int spi_st_runtime_suspend(struct device *dev)
> >+{
> >+	struct spi_master *master = dev_get_drvdata(dev);
> >+	struct spi_st *spi_st = spi_master_get_devdata(master);
> >+
> >+	writel_relaxed(0, spi_st->base + SSC_IEN);
> >+	pinctrl_pm_select_sleep_state(dev);
> >+
> >+	spi_st_clk_disable(spi_st);
> >+
> >+	return 0;
> >+}
> >+
> >+static int spi_st_runtime_resume(struct device *dev)
> >+{
> >+	struct spi_master *master = dev_get_drvdata(dev);
> >+	struct spi_st *spi_st = spi_master_get_devdata(master);
> >+	int ret;
> >+
> >+	ret = spi_st_clk_enable(spi_st);
> >+	pinctrl_pm_select_default_state(dev);
> >+
> >+	return ret;
> >+}
> >+#endif
> >+
> >+#ifdef CONFIG_PM_SLEEP
> >+static int spi_st_suspend(struct device *dev)
> >+{
> >+	struct spi_master *master = dev_get_drvdata(dev);
> >+	int ret;
> >+
> >+	ret = spi_master_suspend(master);
> >+	if (ret)
> >+		return ret;
> >+
> >+	return pm_runtime_force_suspend(dev);
> >+}
> >+
> >+static int spi_st_resume(struct device *dev)
> >+{
> >+	struct spi_master *master = dev_get_drvdata(dev);
> >+	int ret;
> >+
> >+	ret = spi_master_resume(master);
> >+	if (ret)
> >+		return ret;
> >+
> >+	return pm_runtime_force_resume(dev);
> >+}
> >+#endif
> >+
> >+static const struct dev_pm_ops spi_st_pm = {
> >+	SET_SYSTEM_SLEEP_PM_OPS(spi_st_suspend, spi_st_resume)
> >+	SET_RUNTIME_PM_OPS(spi_st_runtime_suspend, spi_st_runtime_resume, NULL)
> >+};
> >+
> >+static struct of_device_id stm_spi_match[] = {
> >+	{ .compatible = "st,comms-ssc4-spi", },
> >+	{},
> >+};
> >+MODULE_DEVICE_TABLE(of, stm_spi_match);
> >+
> >+static struct platform_driver spi_st_driver = {
> >+	.driver = {
> >+		.name = "spi-st",
> >+		.pm = &spi_st_pm,
> >+		.of_match_table = of_match_ptr(stm_spi_match),
> >+	},
> >+	.probe = spi_st_probe,
> >+	.remove = spi_st_remove,
> >+};
> >+module_platform_driver(spi_st_driver);
> >+
> >+MODULE_AUTHOR("Patrice Chotard <patrice.chotard@st.com>");
> >+MODULE_DESCRIPTION("STM SSC SPI driver");
> >+MODULE_LICENSE("GPL v2");
>