[PATCH v2 2/3] SPI: Add i.MX 23/28 SPI driver support

[Michael Grzeschik <m.grzeschik@pengutronix.de>]

Signed-off-by: Michael Grzeschik <m.grzeschik@pengutronix.de>
---
changes since v1:
 - renamed patch to more clear subject
 - whitespace fixes
 - catched more error returns, as EIO
 - explicit affected archs as kconfig dependency
 - used dev_{dbg,info,err} instead of printf
 - removed unneded xzalloc failure catch
 - returning value from driver_register on spi_init

 arch/arm/mach-mxs/include/mach/ssp.h |    2 +
 drivers/spi/Kconfig                  |    5 +
 drivers/spi/Makefile                 |    1 +
 drivers/spi/mxs_spi.c                |  306 ++++++++++++++++++++++++++++++++++
 4 files changed, 314 insertions(+)
 create mode 100644 drivers/spi/mxs_spi.c

diff --git a/arch/arm/mach-mxs/include/mach/ssp.h b/arch/arm/mach-mxs/include/mach/ssp.h
index aa2b27a..5eee5c0 100644
--- a/arch/arm/mach-mxs/include/mach/ssp.h
+++ b/arch/arm/mach-mxs/include/mach/ssp.h
@@ -64,6 +64,7 @@
 #define SSP_CTRL0_BUS_WIDTH(x)		(((x) & 0x3) << 22)
 #define SSP_CTRL0_WAIT_FOR_IRQ		(1 << 21)
 #define SSP_CTRL0_WAIT_FOR_CMD		(1 << 20)
+#define SSP_CTRL0_SSP_ASSERT_OUT(x)	(((x) & 0x3) << 20)
 #define SSP_CTRL0_LONG_RESP		(1 << 19)
 #define SSP_CTRL0_GET_RESP		(1 << 17)
 #define SSP_CTRL0_ENABLE		(1 << 16)
@@ -92,6 +93,7 @@
 /* bit definition for register HW_SSP_CTRL1 */
 #define SSP_CTRL1_POLARITY		(1 << 9)
 #define SSP_CTRL1_PHASE			(1 << 10)
+#define SSP_CTRL1_DMA_ENABLE		(1 << 13)
 #define SSP_CTRL1_WORD_LENGTH(x)	(((x) & 0xf) << 4)
 #define SSP_CTRL1_SSP_MODE(x)		((x) & 0xf)
 
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 10b8fea..f14e28f 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -33,6 +33,11 @@ config DRIVER_SPI_IMX_2_3
 	depends on ARCH_IMX51 || ARCH_IMX53 || ARCH_IMX6
 	default y
 
+config DRIVER_SPI_MXS
+	bool "i.MX (23,28) SPI Master driver"
+	depends on ARCH_IMX23 || ARCH_IMX28
+	depends on SPI
+
 config DRIVER_SPI_OMAP3
 	bool "OMAP3 McSPI Master driver"
 	depends on ARCH_OMAP3
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index b53061e..642b7ec 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -1,5 +1,6 @@
 obj-$(CONFIG_SPI) += spi.o
 obj-$(CONFIG_DRIVER_SPI_IMX) += imx_spi.o
+obj-$(CONFIG_DRIVER_SPI_MXS) += mxs_spi.o
 obj-$(CONFIG_DRIVER_SPI_ALTERA) += altera_spi.o
 obj-$(CONFIG_DRIVER_SPI_ATMEL) += atmel_spi.o
 obj-$(CONFIG_DRIVER_SPI_OMAP3) += omap3_spi.o
diff --git a/drivers/spi/mxs_spi.c b/drivers/spi/mxs_spi.c
new file mode 100644
index 0000000..3c6c11b
--- /dev/null
+++ b/drivers/spi/mxs_spi.c
@@ -0,0 +1,306 @@
+/*
+ * Freescale i.MX28 SPI driver
+ *
+ * Copyright (C) 2013 Michael Grzeschik <mgr@pengutronix.de>
+ *
+ * Copyright (C) 2011 Marek Vasut <marek.vasut@gmail.com>
+ * on behalf of DENX Software Engineering GmbH
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ */
+
+#include <common.h>
+#include <init.h>
+#include <malloc.h>
+#include <spi/spi.h>
+#include <clock.h>
+#include <errno.h>
+#include <io.h>
+#include <linux/clk.h>
+#include <asm/mmu.h>
+#include <mach/generic.h>
+#include <mach/imx-regs.h>
+#include <mach/mxs.h>
+#include <mach/clock.h>
+#include <mach/ssp.h>
+
+#define	MXS_SPI_MAX_TIMEOUT		(10 * MSECOND)
+
+#define	SPI_XFER_BEGIN	0x01 /* Assert CS before transfer */
+#define	SPI_XFER_END	0x02 /* Deassert CS after transfer */
+
+struct mxs_spi {
+	struct spi_master	master;
+	uint32_t		max_khz;
+	uint32_t		mode;
+	struct clk		*clk;
+	void __iomem		*regs;
+};
+
+static inline struct mxs_spi *to_mxs(struct spi_master *master)
+{
+	return container_of(master, struct mxs_spi, master);
+}
+
+/*
+ * Set SSP/MMC bus frequency, in kHz
+ */
+static void imx_set_ssp_busclock(struct spi_master *master, uint32_t freq)
+{
+	struct mxs_spi *mxs = to_mxs(master);
+	const uint32_t sspclk = imx_get_sspclk(master->bus_num);
+	uint32_t val;
+	uint32_t divide, rate, tgtclk;
+
+	/*
+	 * SSP bit rate = SSPCLK / (CLOCK_DIVIDE * (1 + CLOCK_RATE)),
+	 * CLOCK_DIVIDE has to be an even value from 2 to 254, and
+	 * CLOCK_RATE could be any integer from 0 to 255.
+	 */
+	for (divide = 2; divide < 254; divide += 2) {
+		rate = sspclk / freq / divide;
+		if (rate <= 256)
+			break;
+	}
+
+	tgtclk = sspclk / divide / rate;
+	while (tgtclk > freq) {
+		rate++;
+		tgtclk = sspclk / divide / rate;
+	}
+	if (rate > 256)
+		rate = 256;
+
+	/* Always set timeout the maximum */
+	val = SSP_TIMING_TIMEOUT_MASK |
+		SSP_TIMING_CLOCK_DIVIDE(divide) |
+		SSP_TIMING_CLOCK_RATE(rate - 1);
+	writel(val, mxs->regs + HW_SSP_TIMING);
+
+	dev_dbg(master->dev, "SPI%d: Set freq rate to %d KHz (requested %d KHz)\n",
+		master->bus_num, tgtclk, freq);
+}
+
+static int mxs_spi_setup(struct spi_device *spi)
+{
+	struct spi_master *master = spi->master;
+	struct mxs_spi *mxs = to_mxs(master);
+	uint32_t val = 0;
+
+	/* MXS SPI: 4 ports and 3 chip selects maximum */
+	if (master->bus_num > 3 || spi->chip_select > 2) {
+		dev_err(master->dev, "mxs_spi: invalid bus %d / chip select %d\n",
+			 master->bus_num, spi->chip_select);
+		return -EINVAL;
+	}
+
+	mxs_reset_block(mxs->regs + HW_SSP_CTRL0, 0);
+
+	val |= SSP_CTRL0_SSP_ASSERT_OUT(spi->chip_select);
+	val |= SSP_CTRL0_BUS_WIDTH(0);
+	writel(val, mxs->regs + HW_SSP_CTRL0 + BIT_SET);
+
+	val = SSP_CTRL1_SSP_MODE(0) | SSP_CTRL1_WORD_LENGTH(7);
+	val |= (mxs->mode & SPI_CPOL) ? SSP_CTRL1_POLARITY : 0;
+	val |= (mxs->mode & SPI_CPHA) ? SSP_CTRL1_PHASE : 0;
+	writel(val, mxs->regs + HW_SSP_CTRL1);
+
+	writel(0x0, mxs->regs + HW_SSP_CMD0);
+	writel(0x0, mxs->regs + HW_SSP_CMD1);
+
+	imx_set_ssp_busclock(master, spi->max_speed_hz);
+
+	return 0;
+}
+
+static void mxs_spi_start_xfer(struct mxs_spi *mxs)
+{
+	writel(SSP_CTRL0_LOCK_CS, mxs->regs + HW_SSP_CTRL0 + BIT_SET);
+	writel(SSP_CTRL0_IGNORE_CRC, mxs->regs + HW_SSP_CTRL0 + BIT_CLR);
+}
+
+static void mxs_spi_end_xfer(struct mxs_spi *mxs)
+{
+	writel(SSP_CTRL0_LOCK_CS, mxs->regs + HW_SSP_CTRL0 + BIT_CLR);
+	writel(SSP_CTRL0_IGNORE_CRC, mxs->regs + HW_SSP_CTRL0 + BIT_SET);
+}
+
+static uint32_t mxs_spi_cs_to_reg(unsigned cs)
+{
+	uint32_t select = 0;
+
+	if (cs & 1)
+		select |= SSP_CTRL0_WAIT_FOR_CMD;
+	if (cs & 2)
+		select |= SSP_CTRL0_WAIT_FOR_IRQ;
+
+	return select;
+}
+
+static void mxs_spi_set_cs(struct spi_device *spi)
+{
+	const uint32_t mask = SSP_CTRL0_WAIT_FOR_CMD | SSP_CTRL0_WAIT_FOR_IRQ;
+	uint32_t select;
+	struct mxs_spi *mxs = to_mxs(spi->master);
+
+	writel(mask, mxs->regs + HW_SSP_CTRL0 + BIT_CLR);
+	select = mxs_spi_cs_to_reg(spi->chip_select);
+	writel(select, mxs->regs + HW_SSP_CTRL0 + BIT_SET);
+}
+
+static int mxs_spi_xfer_pio(struct spi_device *spi,
+			char *data, int length, int write, unsigned long flags)
+{
+	struct mxs_spi *mxs = to_mxs(spi->master);
+	struct spi_master *master = spi->master;
+
+	if (flags & SPI_XFER_BEGIN)
+		mxs_spi_start_xfer(mxs);
+
+	mxs_spi_set_cs(spi);
+
+	while (length--) {
+		if ((flags & SPI_XFER_END) && !length)
+			mxs_spi_end_xfer(mxs);
+
+		/* We transfer 1 byte */
+		writel(1, mxs->regs + HW_SSP_XFER_COUNT);
+
+		if (write)
+			writel(SSP_CTRL0_READ, mxs->regs + HW_SSP_CTRL0 + BIT_CLR);
+		else
+			writel(SSP_CTRL0_READ, mxs->regs + HW_SSP_CTRL0 + BIT_SET);
+
+		writel(SSP_CTRL0_RUN, mxs->regs + HW_SSP_CTRL0 + BIT_SET);
+
+		if (wait_on_timeout(MXS_SPI_MAX_TIMEOUT,
+				(readl(mxs->regs + HW_SSP_CTRL0) & SSP_CTRL0_RUN) == SSP_CTRL0_RUN)) {
+			dev_err(master->dev, "MXS SPI: Timeout waiting for start\n");
+			return -ETIMEDOUT;
+		}
+
+		if (write)
+			writel(*data++, mxs->regs + HW_SSP_DATA);
+
+		writel(SSP_CTRL0_DATA_XFER, mxs->regs + HW_SSP_CTRL0 + BIT_SET);
+
+		if (!write) {
+			if (wait_on_timeout(MXS_SPI_MAX_TIMEOUT,
+				!(readl(mxs->regs + HW_SSP_STATUS) & SSP_STATUS_FIFO_EMPTY))) {
+				dev_err(master->dev, "MXS SPI: Timeout waiting for data\n");
+				return -ETIMEDOUT;
+			}
+
+			*data++ = readl(mxs->regs + HW_SSP_DATA) & 0xff;
+		}
+
+		if (wait_on_timeout(MXS_SPI_MAX_TIMEOUT,
+			!(readl(mxs->regs + HW_SSP_CTRL0) & SSP_CTRL0_RUN))) {
+			dev_err(master->dev, "MXS SPI: Timeout waiting for finish\n");
+			return -ETIMEDOUT;
+		}
+	}
+
+	return 0;
+}
+
+static int mxs_spi_transfer(struct spi_device *spi, struct spi_message *mesg)
+{
+	struct mxs_spi *mxs = to_mxs(spi->master);
+	struct spi_master *master = spi->master;
+	struct spi_transfer *t = NULL;
+	char dummy;
+	unsigned long flags = 0;
+	int write = 0;
+	char *data = NULL;
+	int ret;
+	mesg->actual_length = 0;
+
+	list_for_each_entry(t, &mesg->transfers, transfer_list) {
+		flags = 0;
+
+		if (t->tx_buf) {
+			data = (char *) t->tx_buf;
+			write = 1;
+		} else if (t->rx_buf) {
+			data = (char *) t->rx_buf;
+			write = 0;
+		}
+
+		if (&t->transfer_list == mesg->transfers.next)
+			flags |= SPI_XFER_BEGIN;
+
+		if (&t->transfer_list == mesg->transfers.prev)
+			flags |= SPI_XFER_END;
+
+		if ((t->rx_buf && t->tx_buf)) {
+			dev_err(master->dev, "Cannot send and receive simultaneously\n");
+			return -EIO;
+		}
+
+		if ((!t->rx_buf && !t->tx_buf)) {
+			dev_err(master->dev, "No Data\n");
+			return -EIO;
+		}
+
+		if (t->len == 0) {
+			if (flags == SPI_XFER_END) {
+				t->len = 1;
+				t->rx_buf = (void *) &dummy;
+			} else {
+				return 0;
+			}
+		}
+
+		writel(SSP_CTRL1_DMA_ENABLE, mxs->regs + HW_SSP_CTRL1 + BIT_CLR);
+		ret = mxs_spi_xfer_pio(spi, data, t->len, write, flags);
+		if (ret < 0)
+			return ret;
+		mesg->actual_length += t->len;
+	}
+
+	return 0;
+}
+
+static int mxs_spi_probe(struct device_d *dev)
+{
+	struct spi_master *master;
+	struct mxs_spi *mxs;
+
+	mxs = xzalloc(sizeof(*mxs));
+
+	master = &mxs->master;
+	master->dev = dev;
+
+	master->bus_num = dev->id;
+	master->setup = mxs_spi_setup;
+	master->transfer = mxs_spi_transfer;
+	master->num_chipselect = 3;
+	mxs->mode = SPI_CPOL | SPI_CPHA;
+
+	mxs->regs = dev_request_mem_region(dev, 0);
+
+	spi_register_master(master);
+
+	return 0;
+}
+
+static struct driver_d mxs_spi_driver = {
+	.name  = "mxs_spi",
+	.probe = mxs_spi_probe,
+};
+
+static int __init mxs_spi_init(void)
+{
+	return platform_driver_register(&mxs_spi_driver);
+}
+
+device_initcall(mxs_spi_init);
+
+MODULE_AUTHOR("Denx Software Engeneering and Michael Grzeschik");
+MODULE_DESCRIPTION("MXS SPI driver");
+MODULE_LICENSE("GPL");
-- 
1.7.10.4


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