[PATCH] SPI controller driver for OMAP Microwire

This adds a SPI driver for the Microwire controller on OMAP1 chips.  This
driver has been used in the Linux-OMAP tree for some time now, including
with some of those displays using standardized 9-bit commands followed by
data with 8-bit words.

Microwire only supports half duplex transfers, but that's all that most SPI
protocols need.  When full duplex, or higher speeds, are needed there are
several other controllers that can be used on OMAP.

[akpm@osdl.org: cleanups]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Imre Deak <imre.deak@solidboot.com>
Signed-off-by: Juha Yrjola <juha.yrjola@solidboot.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/spi/Kconfig

@@ -87,6 +87,13 @@ config SPI_MPC83xx
 	  family of PowerPC processors.  The MPC83xx uses a simple set of shift
 	  registers for data (opposed to the CPM based descriptor model).
 
+config SPI_OMAP_UWIRE
+	tristate "OMAP1 MicroWire"
+	depends on SPI_MASTER && ARCH_OMAP1
+	select SPI_BITBANG
+	help
+	  This hooks up to the MicroWire controller on OMAP1 chips.
+
 config SPI_PXA2XX
 	tristate "PXA2xx SSP SPI master"
 	depends on SPI_MASTER && ARCH_PXA && EXPERIMENTAL

drivers/spi/Makefile

@@ -14,6 +14,7 @@ obj-$(CONFIG_SPI_MASTER)		+= spi.o
 obj-$(CONFIG_SPI_BITBANG)		+= spi_bitbang.o
 obj-$(CONFIG_SPI_BUTTERFLY)		+= spi_butterfly.o
 obj-$(CONFIG_SPI_PXA2XX)		+= pxa2xx_spi.o
+obj-$(CONFIG_SPI_OMAP_UWIRE)		+= omap_uwire.o
 obj-$(CONFIG_SPI_MPC83xx)		+= spi_mpc83xx.o
 obj-$(CONFIG_SPI_S3C24XX_GPIO)		+= spi_s3c24xx_gpio.o
 obj-$(CONFIG_SPI_S3C24XX)		+= spi_s3c24xx.o

drivers/spi/omap_uwire.c

@@ -0,0 +1,572 @@
+/*
+ * omap_uwire.c -- MicroWire interface driver for OMAP
+ *
+ * Copyright 2003 MontaVista Software Inc. <source@mvista.com>
+ *
+ * Ported to 2.6 OMAP uwire interface.
+ * Copyright (C) 2004 Texas Instruments.
+ *
+ * Generalization patches by Juha Yrjola <juha.yrjola@nokia.com>
+ *
+ * Copyright (C) 2005 David Brownell (ported to 2.6 SPI interface)
+ * Copyright (C) 2006 Nokia
+ *
+ * Many updates by Imre Deak <imre.deak@nokia.com>
+ *
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
+ * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/platform_device.h>
+#include <linux/workqueue.h>
+#include <linux/interrupt.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+
+#include <linux/spi/spi.h>
+#include <linux/spi/spi_bitbang.h>
+
+#include <asm/system.h>
+#include <asm/irq.h>
+#include <asm/hardware.h>
+#include <asm/io.h>
+#include <asm/mach-types.h>
+
+#include <asm/arch/mux.h>
+#include <asm/arch/omap730.h>	/* OMAP730_IO_CONF registers */
+
+
+/* FIXME address is now a platform device resource,
+ * and irqs should show there too...
+ */
+#define UWIRE_BASE_PHYS		0xFFFB3000
+#define UWIRE_BASE		((void *__iomem)IO_ADDRESS(UWIRE_BASE_PHYS))
+
+/* uWire Registers: */
+#define UWIRE_IO_SIZE 0x20
+#define UWIRE_TDR     0x00
+#define UWIRE_RDR     0x00
+#define UWIRE_CSR     0x01
+#define UWIRE_SR1     0x02
+#define UWIRE_SR2     0x03
+#define UWIRE_SR3     0x04
+#define UWIRE_SR4     0x05
+#define UWIRE_SR5     0x06
+
+/* CSR bits */
+#define	RDRB	(1 << 15)
+#define	CSRB	(1 << 14)
+#define	START	(1 << 13)
+#define	CS_CMD	(1 << 12)
+
+/* SR1 or SR2 bits */
+#define UWIRE_READ_FALLING_EDGE		0x0001
+#define UWIRE_READ_RISING_EDGE		0x0000
+#define UWIRE_WRITE_FALLING_EDGE	0x0000
+#define UWIRE_WRITE_RISING_EDGE		0x0002
+#define UWIRE_CS_ACTIVE_LOW		0x0000
+#define UWIRE_CS_ACTIVE_HIGH		0x0004
+#define UWIRE_FREQ_DIV_2		0x0000
+#define UWIRE_FREQ_DIV_4		0x0008
+#define UWIRE_FREQ_DIV_8		0x0010
+#define UWIRE_CHK_READY			0x0020
+#define UWIRE_CLK_INVERTED		0x0040
+
+
+struct uwire_spi {
+	struct spi_bitbang	bitbang;
+	struct clk		*ck;
+};
+
+struct uwire_state {
+	unsigned	bits_per_word;
+	unsigned	div1_idx;
+};
+
+/* REVISIT compile time constant for idx_shift? */
+static unsigned int uwire_idx_shift;
+
+static inline void uwire_write_reg(int idx, u16 val)
+{
+	__raw_writew(val, UWIRE_BASE + (idx << uwire_idx_shift));
+}
+
+static inline u16 uwire_read_reg(int idx)
+{
+	return __raw_readw(UWIRE_BASE + (idx << uwire_idx_shift));
+}
+
+static inline void omap_uwire_configure_mode(u8 cs, unsigned long flags)
+{
+	u16	w, val = 0;
+	int	shift, reg;
+
+	if (flags & UWIRE_CLK_INVERTED)
+		val ^= 0x03;
+	val = flags & 0x3f;
+	if (cs & 1)
+		shift = 6;
+	else
+		shift = 0;
+	if (cs <= 1)
+		reg = UWIRE_SR1;
+	else
+		reg = UWIRE_SR2;
+
+	w = uwire_read_reg(reg);
+	w &= ~(0x3f << shift);
+	w |= val << shift;
+	uwire_write_reg(reg, w);
+}
+
+static int wait_uwire_csr_flag(u16 mask, u16 val, int might_not_catch)
+{
+	u16 w;
+	int c = 0;
+	unsigned long max_jiffies = jiffies + HZ;
+
+	for (;;) {
+		w = uwire_read_reg(UWIRE_CSR);
+		if ((w & mask) == val)
+			break;
+		if (time_after(jiffies, max_jiffies)) {
+			printk(KERN_ERR "%s: timeout. reg=%#06x "
+					"mask=%#06x val=%#06x\n",
+			       __FUNCTION__, w, mask, val);
+			return -1;
+		}
+		c++;
+		if (might_not_catch && c > 64)
+			break;
+	}
+	return 0;
+}
+
+static void uwire_set_clk1_div(int div1_idx)
+{
+	u16 w;
+
+	w = uwire_read_reg(UWIRE_SR3);
+	w &= ~(0x03 << 1);
+	w |= div1_idx << 1;
+	uwire_write_reg(UWIRE_SR3, w);
+}
+
+static void uwire_chipselect(struct spi_device *spi, int value)
+{
+	struct	uwire_state *ust = spi->controller_state;
+	u16	w;
+	int	old_cs;
+
+
+	BUG_ON(wait_uwire_csr_flag(CSRB, 0, 0));
+
+	w = uwire_read_reg(UWIRE_CSR);
+	old_cs = (w >> 10) & 0x03;
+	if (value == BITBANG_CS_INACTIVE || old_cs != spi->chip_select) {
+		/* Deselect this CS, or the previous CS */
+		w &= ~CS_CMD;
+		uwire_write_reg(UWIRE_CSR, w);
+	}
+	/* activate specfied chipselect */
+	if (value == BITBANG_CS_ACTIVE) {
+		uwire_set_clk1_div(ust->div1_idx);
+		/* invert clock? */
+		if (spi->mode & SPI_CPOL)
+			uwire_write_reg(UWIRE_SR4, 1);
+		else
+			uwire_write_reg(UWIRE_SR4, 0);
+
+		w = spi->chip_select << 10;
+		w |= CS_CMD;
+		uwire_write_reg(UWIRE_CSR, w);
+	}
+}
+
+static int uwire_txrx(struct spi_device *spi, struct spi_transfer *t)
+{
+	struct uwire_state *ust = spi->controller_state;
+	unsigned	len = t->len;
+	unsigned	bits = ust->bits_per_word;
+	unsigned	bytes;
+	u16		val, w;
+	int		status = 0;;
+
+	if (!t->tx_buf && !t->rx_buf)
+		return 0;
+
+	/* Microwire doesn't read and write concurrently */
+	if (t->tx_buf && t->rx_buf)
+		return -EPERM;
+
+	w = spi->chip_select << 10;
+	w |= CS_CMD;
+
+	if (t->tx_buf) {
+		const u8	*buf = t->tx_buf;
+
+		/* NOTE:  DMA could be used for TX transfers */
+
+		/* write one or two bytes at a time */
+		while (len >= 1) {
+			/* tx bit 15 is first sent; we byteswap multibyte words
+			 * (msb-first) on the way out from memory.
+			 */
+			val = *buf++;
+			if (bits > 8) {
+				bytes = 2;
+				val |= *buf++ << 8;
+			} else
+				bytes = 1;
+			val <<= 16 - bits;
+
+#ifdef	VERBOSE
+			pr_debug("%s: write-%d =%04x\n",
+					spi->dev.bus_id, bits, val);
+#endif
+			if (wait_uwire_csr_flag(CSRB, 0, 0))
+				goto eio;
+
+			uwire_write_reg(UWIRE_TDR, val);
+
+			/* start write */
+			val = START | w | (bits << 5);
+
+			uwire_write_reg(UWIRE_CSR, val);
+			len -= bytes;
+
+			/* Wait till write actually starts.
+			 * This is needed with MPU clock 60+ MHz.
+			 * REVISIT: we may not have time to catch it...
+			 */
+			if (wait_uwire_csr_flag(CSRB, CSRB, 1))
+				goto eio;
+
+			status += bytes;
+		}
+
+		/* REVISIT:  save this for later to get more i/o overlap */
+		if (wait_uwire_csr_flag(CSRB, 0, 0))
+			goto eio;
+
+	} else if (t->rx_buf) {
+		u8		*buf = t->rx_buf;
+
+		/* read one or two bytes at a time */
+		while (len) {
+			if (bits > 8) {
+				bytes = 2;
+			} else
+				bytes = 1;
+
+			/* start read */
+			val = START | w | (bits << 0);
+			uwire_write_reg(UWIRE_CSR, val);
+			len -= bytes;
+
+			/* Wait till read actually starts */
+			(void) wait_uwire_csr_flag(CSRB, CSRB, 1);
+
+			if (wait_uwire_csr_flag(RDRB | CSRB,
+						RDRB, 0))
+				goto eio;
+
+			/* rx bit 0 is last received; multibyte words will
+			 * be properly byteswapped on the way to memory.
+			 */
+			val = uwire_read_reg(UWIRE_RDR);
+			val &= (1 << bits) - 1;
+			*buf++ = (u8) val;
+			if (bytes == 2)
+				*buf++ = val >> 8;
+			status += bytes;
+#ifdef	VERBOSE
+			pr_debug("%s: read-%d =%04x\n",
+					spi->dev.bus_id, bits, val);
+#endif
+
+		}
+	}
+	return status;
+eio:
+	return -EIO;
+}
+
+static int uwire_setup_transfer(struct spi_device *spi, struct spi_transfer *t)
+{
+	struct uwire_state	*ust = spi->controller_state;
+	struct uwire_spi	*uwire;
+	unsigned		flags = 0;
+	unsigned		bits;
+	unsigned		hz;
+	unsigned long		rate;
+	int			div1_idx;
+	int			div1;
+	int			div2;
+	int			status;
+
+	uwire = spi_master_get_devdata(spi->master);
+
+	if (spi->chip_select > 3) {
+		pr_debug("%s: cs%d?\n", spi->dev.bus_id, spi->chip_select);
+		status = -ENODEV;
+		goto done;
+	}
+
+	bits = spi->bits_per_word;
+	if (t != NULL && t->bits_per_word)
+		bits = t->bits_per_word;
+	if (!bits)
+		bits = 8;
+
+	if (bits > 16) {
+		pr_debug("%s: wordsize %d?\n", spi->dev.bus_id, bits);
+		status = -ENODEV;
+		goto done;
+	}
+	ust->bits_per_word = bits;
+
+	/* mode 0..3, clock inverted separately;
+	 * standard nCS signaling;
+	 * don't treat DI=high as "not ready"
+	 */
+	if (spi->mode & SPI_CS_HIGH)
+		flags |= UWIRE_CS_ACTIVE_HIGH;
+
+	if (spi->mode & SPI_CPOL)
+		flags |= UWIRE_CLK_INVERTED;
+
+	switch (spi->mode & (SPI_CPOL | SPI_CPHA)) {
+	case SPI_MODE_0:
+	case SPI_MODE_3:
+		flags |= UWIRE_WRITE_RISING_EDGE | UWIRE_READ_FALLING_EDGE;
+		break;
+	case SPI_MODE_1:
+	case SPI_MODE_2:
+		flags |= UWIRE_WRITE_FALLING_EDGE | UWIRE_READ_RISING_EDGE;
+		break;
+	}
+
+	/* assume it's already enabled */
+	rate = clk_get_rate(uwire->ck);
+
+	hz = spi->max_speed_hz;
+	if (t != NULL && t->speed_hz)
+		hz = t->speed_hz;
+
+	if (!hz) {
+		pr_debug("%s: zero speed?\n", spi->dev.bus_id);
+		status = -EINVAL;
+		goto done;
+	}
+
+	/* F_INT = mpu_xor_clk / DIV1 */
+	for (div1_idx = 0; div1_idx < 4; div1_idx++) {
+		switch (div1_idx) {
+		case 0:
+			div1 = 2;
+			break;
+		case 1:
+			div1 = 4;
+			break;
+		case 2:
+			div1 = 7;
+			break;
+		default:
+		case 3:
+			div1 = 10;
+			break;
+		}
+		div2 = (rate / div1 + hz - 1) / hz;
+		if (div2 <= 8)
+			break;
+	}
+	if (div1_idx == 4) {
+		pr_debug("%s: lowest clock %ld, need %d\n",
+			spi->dev.bus_id, rate / 10 / 8, hz);
+		status = -EDOM;
+		goto done;
+	}
+
+	/* we have to cache this and reset in uwire_chipselect as this is a
+	 * global parameter and another uwire device can change it under
+	 * us */
+	ust->div1_idx = div1_idx;
+	uwire_set_clk1_div(div1_idx);
+
+	rate /= div1;
+
+	switch (div2) {
+	case 0:
+	case 1:
+	case 2:
+		flags |= UWIRE_FREQ_DIV_2;
+		rate /= 2;
+		break;
+	case 3:
+	case 4:
+		flags |= UWIRE_FREQ_DIV_4;
+		rate /= 4;
+		break;
+	case 5:
+	case 6:
+	case 7:
+	case 8:
+		flags |= UWIRE_FREQ_DIV_8;
+		rate /= 8;
+		break;
+	}
+	omap_uwire_configure_mode(spi->chip_select, flags);
+	pr_debug("%s: uwire flags %02x, armxor %lu KHz, SCK %lu KHz\n",
+			__FUNCTION__, flags,
+			clk_get_rate(uwire->ck) / 1000,
+			rate / 1000);
+	status = 0;
+done:
+	return status;
+}
+
+static int uwire_setup(struct spi_device *spi)
+{
+	struct uwire_state *ust = spi->controller_state;
+
+	if (ust == NULL) {
+		ust = kzalloc(sizeof(*ust), GFP_KERNEL);
+		if (ust == NULL)
+			return -ENOMEM;
+		spi->controller_state = ust;
+	}
+
+	return uwire_setup_transfer(spi, NULL);
+}
+
+static void uwire_cleanup(const struct spi_device *spi)
+{
+	kfree(spi->controller_state);
+}
+
+static void uwire_off(struct uwire_spi *uwire)
+{
+	uwire_write_reg(UWIRE_SR3, 0);
+	clk_disable(uwire->ck);
+	clk_put(uwire->ck);
+	spi_master_put(uwire->bitbang.master);
+}
+
+static int uwire_probe(struct platform_device *pdev)
+{
+	struct spi_master	*master;
+	struct uwire_spi	*uwire;
+	int			status;
+
+	master = spi_alloc_master(&pdev->dev, sizeof *uwire);
+	if (!master)
+		return -ENODEV;
+
+	uwire = spi_master_get_devdata(master);
+	dev_set_drvdata(&pdev->dev, uwire);
+
+	uwire->ck = clk_get(&pdev->dev, "armxor_ck");
+	if (!uwire->ck || IS_ERR(uwire->ck)) {
+		dev_dbg(&pdev->dev, "no mpu_xor_clk ?\n");
+		spi_master_put(master);
+		return -ENODEV;
+	}
+	clk_enable(uwire->ck);
+
+	if (cpu_is_omap730())
+		uwire_idx_shift = 1;
+	else
+		uwire_idx_shift = 2;
+
+	uwire_write_reg(UWIRE_SR3, 1);
+
+	master->bus_num = 2;	/* "official" */
+	master->num_chipselect = 4;
+	master->setup = uwire_setup;
+	master->cleanup = uwire_cleanup;
+
+	uwire->bitbang.master = master;
+	uwire->bitbang.chipselect = uwire_chipselect;
+	uwire->bitbang.setup_transfer = uwire_setup_transfer;
+	uwire->bitbang.txrx_bufs = uwire_txrx;
+
+	status = spi_bitbang_start(&uwire->bitbang);
+	if (status < 0)
+		uwire_off(uwire);
+	return status;
+}
+
+static int uwire_remove(struct platform_device *pdev)
+{
+	struct uwire_spi	*uwire = dev_get_drvdata(&pdev->dev);
+	int			status;
+
+	// FIXME remove all child devices, somewhere ...
+
+	status = spi_bitbang_stop(&uwire->bitbang);
+	uwire_off(uwire);
+	return status;
+}
+
+static struct platform_driver uwire_driver = {
+	.driver = {
+		.name		= "omap_uwire",
+		.bus		= &platform_bus_type,
+		.owner		= THIS_MODULE,
+	},
+	.probe		= uwire_probe,
+	.remove		= uwire_remove,
+	// suspend ... unuse ck
+	// resume ... use ck
+};
+
+static int __init omap_uwire_init(void)
+{
+	/* FIXME move these into the relevant board init code. also, include
+	 * H3 support; it uses tsc2101 like H2 (on a different chipselect).
+	 */
+
+	if (machine_is_omap_h2()) {
+		/* defaults: W21 SDO, U18 SDI, V19 SCL */
+		omap_cfg_reg(N14_1610_UWIRE_CS0);
+		omap_cfg_reg(N15_1610_UWIRE_CS1);
+	}
+	if (machine_is_omap_perseus2()) {
+		/* configure pins: MPU_UW_nSCS1, MPU_UW_SDO, MPU_UW_SCLK */
+		int val = omap_readl(OMAP730_IO_CONF_9) & ~0x00EEE000;
+		omap_writel(val | 0x00AAA000, OMAP730_IO_CONF_9);
+	}
+
+	return platform_driver_register(&uwire_driver);
+}
+
+static void __exit omap_uwire_exit(void)
+{
+	platform_driver_unregister(&uwire_driver);
+}
+
+subsys_initcall(omap_uwire_init);
+module_exit(omap_uwire_exit);
+
+MODULE_LICENSE("GPL");
+