Re: [STLinux Kernel] [PATCH v2 1/4] spi: Add new driver for STMicroelectronics' SPI Controller
From: Patrice Chotard
Date: Tue Dec 02 2014 - 11:17:48 EST
Hi Lee
Some minors remarks below
Thanks
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@xxxxxxxxxx>
---
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@xxxxxx>
+ * Patrice Chotard <patrice.chotard@xxxxxx>
+ * Lee Jones <lee.jones@xxxxxxxxxx>
+ *
+ * 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@xxxxxx>");
+MODULE_DESCRIPTION("STM SSC SPI driver");
+MODULE_LICENSE("GPL v2");
--
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