[PATCH] i2c: SuperH Mobile I2C Bus Controller V5

[Magnus Damm <magnus.damm@gmail.com>]

This is V5 of the SuperH Mobile I2C Controller Driver. A simple Master
only driver for the I2C block included in processors such as sh7343,
sh7722 and sh7723. Tested on a sh7722 MigoR using a rs5c732b rtc.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
---

 Changes since V4:
  - Use sh_mobile_i2c_op enum
  - Remove fast_mode and rx_ack_high code
  - Use variable name retry_count instead of k
  - Encoding fixes
  - Use clk_enable() and clk_disable()
  - Remove deactivate_ch() call from setup_channel()
  - Use dev_err() if i2c_add_numbered_adapter() fails
  - MODULE_LICENSE("GPL v2")
  - Comment fix, cleaned up header
 Changes since V3:
  - Added SUPERH Kconfig dependency
  - Use spin_lock_irqsave() and spin_unlock_irqrestore()
  - Use IRQF_DISABLED
  - Checkpatch fixes
 Changes since V2:
  - dev_xxx() use
  - Kill off superfluous ioarea resource
  - Add SMBus emulation
 Changes since V1:
  - Use clk_get()/clk_put()/clk_get_rate() to get peripheral clock rate.
  - Use pdev->dev.bus_id instead of dev->name

 Verified with the rtc-rs5c372 SMBus conversion patches currently in -mm.

 drivers/i2c/busses/Kconfig         |   10 
 drivers/i2c/busses/Makefile        |    1 
 drivers/i2c/busses/i2c-sh_mobile.c |  500 ++++++++++++++++++++++++++++++++++++
 3 files changed, 511 insertions(+)

--- 0001/drivers/i2c/busses/Kconfig
+++ work/drivers/i2c/busses/Kconfig	2008-04-01 20:16:55.000000000 +0900
@@ -672,4 +672,14 @@ config I2C_PMCMSP
 	  This driver can also be built as module. If so, the module
 	  will be called i2c-pmcmsp.
 
+config I2C_SH_MOBILE
+	tristate "SuperH Mobile I2C Controller"
+	depends on SUPERH
+	help
+	  If you say yes to this option, support will be included for the
+	  built-in I2C interface on the Renesas SH-Mobile processor.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-sh_mobile.
+
 endmenu
--- 0001/drivers/i2c/busses/Makefile
+++ work/drivers/i2c/busses/Makefile	2008-04-01 20:16:55.000000000 +0900
@@ -52,6 +52,7 @@ obj-$(CONFIG_I2C_VIAPRO)	+= i2c-viapro.o
 obj-$(CONFIG_I2C_VOODOO3)	+= i2c-voodoo3.o
 obj-$(CONFIG_SCx200_ACB)	+= scx200_acb.o
 obj-$(CONFIG_SCx200_I2C)	+= scx200_i2c.o
+obj-$(CONFIG_I2C_SH_MOBILE)	+= i2c-sh_mobile.o
 
 ifeq ($(CONFIG_I2C_DEBUG_BUS),y)
 EXTRA_CFLAGS += -DDEBUG
--- /dev/null
+++ work/drivers/i2c/busses/i2c-sh_mobile.c	2008-04-02 10:28:42.000000000 +0900
@@ -0,0 +1,500 @@
+/*
+ * SuperH Mobile I2C Controller
+ *
+ * Copyright (C) 2008 Magnus Damm
+ *
+ * Portions of the code based on out-of-tree driver i2c-sh7343.c
+ * Copyright (c) 2006 Carlos Munoz <carlos@kenati.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
+ *
+ * This program is distributed in the hope that 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, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/platform_device.h>
+#include <linux/interrupt.h>
+#include <linux/i2c.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+
+enum sh_mobile_i2c_op {
+	OP_START = 0,
+	OP_TX_ONLY,
+	OP_TX_STOP,
+	OP_TX_TO_RX,
+	OP_RX_ONLY,
+	OP_RX_STOP,
+};
+
+struct sh_mobile_i2c_data {
+	struct device *dev;
+	void __iomem *reg;
+	struct i2c_adapter adap;
+
+	struct clk *clk;
+	u_int8_t iccl;
+	u_int8_t icch;
+
+	spinlock_t lock;
+	wait_queue_head_t wait;
+	struct i2c_msg *msg;
+	int pos;
+	int sr;
+};
+
+#define NORMAL_SPEED		100000 /* FAST_SPEED 400000 */
+
+/* Register offsets */
+#define ICDR(pd)		(pd->reg + 0x00)
+#define ICCR(pd)		(pd->reg + 0x04)
+#define ICSR(pd)		(pd->reg + 0x08)
+#define ICIC(pd)		(pd->reg + 0x0c)
+#define ICCL(pd)		(pd->reg + 0x10)
+#define ICCH(pd)		(pd->reg + 0x14)
+
+/* Register bits */
+#define ICCR_ICE		0x80
+#define ICCR_RACK		0x40
+#define ICCR_TRS		0x10
+#define ICCR_BBSY		0x04
+#define ICCR_SCP		0x01
+
+#define ICSR_SCLM		0x80
+#define ICSR_SDAM		0x40
+#define SW_DONE			0x20
+#define ICSR_BUSY		0x10
+#define ICSR_AL			0x08
+#define ICSR_TACK		0x04
+#define ICSR_WAIT		0x02
+#define ICSR_DTE		0x01
+
+#define ICIC_ALE		0x08
+#define ICIC_TACKE		0x04
+#define ICIC_WAITE		0x02
+#define ICIC_DTEE		0x01
+
+static void activate_ch(struct sh_mobile_i2c_data *pd)
+{
+	/* Make sure the clock is enabled */
+	clk_enable(pd->clk);
+
+	/* Enable channel and configure rx ack */
+	iowrite8(ioread8(ICCR(pd)) | ICCR_ICE, ICCR(pd));
+
+	/* Mask all interrupts */
+	iowrite8(0, ICIC(pd));
+
+	/* Set the clock */
+	iowrite8(pd->iccl, ICCL(pd));
+	iowrite8(pd->icch, ICCH(pd));
+}
+
+static void deactivate_ch(struct sh_mobile_i2c_data *pd)
+{
+	/* Clear/disable interrupts */
+	iowrite8(0, ICSR(pd));
+	iowrite8(0, ICIC(pd));
+
+	/* Disable channel */
+	iowrite8(ioread8(ICCR(pd)) & ~ICCR_ICE, ICCR(pd));
+
+	/* Disable clock */
+	clk_disable(pd->clk);
+}
+
+static unsigned char i2c_op(struct sh_mobile_i2c_data *pd,
+			    enum sh_mobile_i2c_op op, unsigned char data)
+{
+	unsigned char ret = 0;
+	unsigned long flags;
+
+	dev_dbg(pd->dev, "op %d, data in 0x%02x\n", op, data);
+
+	spin_lock_irqsave(&pd->lock, flags);
+
+	switch (op) {
+	case OP_START:
+		iowrite8(0x94, ICCR(pd));
+		break;
+	case OP_TX_ONLY:
+		iowrite8(data, ICDR(pd));
+		break;
+	case OP_TX_STOP:
+		iowrite8(data, ICDR(pd));
+		iowrite8(0x90, ICCR(pd));
+		iowrite8(ICIC_ALE | ICIC_TACKE, ICIC(pd));
+		break;
+	case OP_TX_TO_RX:
+		iowrite8(data, ICDR(pd));
+		iowrite8(0x81, ICCR(pd));
+		break;
+	case OP_RX_ONLY:
+		ret = ioread8(ICDR(pd));
+		break;
+	case OP_RX_STOP:
+		ret = ioread8(ICDR(pd));
+		iowrite8(0xc0, ICCR(pd));
+		break;
+	}
+
+	spin_unlock_irqrestore(&pd->lock, flags);
+
+	dev_dbg(pd->dev, "op %d, data out 0x%02x\n", op, ret);
+	return ret;
+}
+
+static irqreturn_t sh_mobile_i2c_isr(int irq, void *dev_id)
+{
+	struct platform_device *dev = dev_id;
+	struct sh_mobile_i2c_data *pd = platform_get_drvdata(dev);
+	struct i2c_msg *msg = pd->msg;
+	unsigned char data, sr;
+	int wakeup = 0;
+
+	sr = ioread8(ICSR(pd));
+	pd->sr |= sr;
+
+	dev_dbg(pd->dev, "i2c_isr 0x%02x 0x%02x %s %d %d!\n", sr, pd->sr,
+	       (msg->flags & I2C_M_RD) ? "read" : "write",
+	       pd->pos, msg->len);
+
+	if (sr & (ICSR_AL | ICSR_TACK)) {
+		iowrite8(0, ICIC(pd)); /* disable interrupts */
+		wakeup = 1;
+		goto do_wakeup;
+	}
+
+	if (pd->pos == msg->len) {
+		i2c_op(pd, OP_RX_ONLY, 0);
+		wakeup = 1;
+		goto do_wakeup;
+	}
+
+	if (pd->pos == -1) {
+		data = (msg->addr & 0x7f) << 1;
+		data |= (msg->flags & I2C_M_RD) ? 1 : 0;
+	} else
+		data = msg->buf[pd->pos];
+
+	if ((pd->pos == -1) || !(msg->flags & I2C_M_RD)) {
+		if (msg->flags & I2C_M_RD)
+			i2c_op(pd, OP_TX_TO_RX, data);
+		else if (pd->pos == (msg->len - 1)) {
+			i2c_op(pd, OP_TX_STOP, data);
+			wakeup = 1;
+		} else
+			i2c_op(pd, OP_TX_ONLY, data);
+	} else {
+		if (pd->pos == (msg->len - 1))
+			data = i2c_op(pd, OP_RX_STOP, 0);
+		else
+			data = i2c_op(pd, OP_RX_ONLY, 0);
+
+		msg->buf[pd->pos] = data;
+	}
+	pd->pos++;
+
+ do_wakeup:
+	if (wakeup) {
+		pd->sr |= SW_DONE;
+		wake_up(&pd->wait);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int start_ch(struct sh_mobile_i2c_data *pd, struct i2c_msg *usr_msg)
+{
+	/* Initialize channel registers */
+	iowrite8(ioread8(ICCR(pd)) & ~ICCR_ICE, ICCR(pd));
+
+	/* Enable channel and configure rx ack */
+	iowrite8(ioread8(ICCR(pd)) | ICCR_ICE, ICCR(pd));
+
+	/* Set the clock */
+	iowrite8(pd->iccl, ICCL(pd));
+	iowrite8(pd->icch, ICCH(pd));
+
+	pd->msg = usr_msg;
+	pd->pos = -1;
+	pd->sr = 0;
+
+	/* Enable all interrupts except wait */
+	iowrite8(ioread8(ICIC(pd)) | ICIC_ALE | ICIC_TACKE | ICIC_DTEE,
+		 ICIC(pd));
+	return 0;
+}
+
+static int sh_mobile_i2c_xfer(struct i2c_adapter *adapter,
+			      struct i2c_msg *msgs,
+			      int num)
+{
+	struct sh_mobile_i2c_data *pd = i2c_get_adapdata(adapter);
+	struct i2c_msg	*msg;
+	int err = 0;
+	u_int8_t val;
+	int i, k, retry_count;
+
+	activate_ch(pd);
+
+	/* Process all messages */
+	for (i = 0; i < num; i++) {
+		msg = &msgs[i];
+
+		err = start_ch(pd, msg);
+		if (err)
+			break;
+
+		i2c_op(pd, OP_START, 0);
+
+		/* The interrupt handler takes care of the rest... */
+		k = wait_event_timeout(pd->wait,
+				       pd->sr & (ICSR_TACK | SW_DONE),
+				       5 * HZ);
+		if (!k)
+			dev_err(pd->dev, "Transfer request timed out\n");
+
+		retry_count = 10;
+again:
+		val = ioread8(ICSR(pd));
+
+		dev_dbg(pd->dev, "val 0x%02x pd->sr 0x%02x\n", val, pd->sr);
+
+		if ((val | pd->sr) & (ICSR_TACK | ICSR_AL)) {
+			err = -EIO;
+			break;
+		}
+
+		/* the interrupt handler may wake us up before the
+		 * transfer is finished, so poll the hardware
+		 * until we're done.
+		 */
+
+		if (!(!(val & ICSR_BUSY) && (val & ICSR_SCLM) &&
+		      (val & ICSR_SDAM))) {
+			msleep(1);
+			if (retry_count--)
+				goto again;
+
+			err = -EIO;
+			dev_err(pd->dev, "Polling timed out\n");
+			break;
+		}
+	}
+
+	deactivate_ch(pd);
+
+	if (!err)
+		err = num;
+	return err;
+}
+
+static u32 sh_mobile_i2c_func(struct i2c_adapter *adapter)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static struct i2c_algorithm sh_mobile_i2c_algorithm = {
+	.functionality	= sh_mobile_i2c_func,
+	.master_xfer	= sh_mobile_i2c_xfer,
+};
+
+static void sh_mobile_i2c_setup_channel(struct platform_device *dev)
+{
+	struct sh_mobile_i2c_data *pd = platform_get_drvdata(dev);
+	unsigned long peripheral_clk = clk_get_rate(pd->clk);
+	u_int32_t num;
+	u_int32_t denom;
+	u_int32_t tmp;
+
+	spin_lock_init(&pd->lock);
+	init_waitqueue_head(&pd->wait);
+
+	/* Calculate the value for iccl. From the data sheet:
+	 * iccl = (p clock / transfer rate) * (L / (L + H))
+	 * where L and H are the SCL low/high ratio (5/4 in this case).
+	 * We also round off the result.
+	 */
+	num = peripheral_clk * 5;
+	denom = NORMAL_SPEED * 9;
+	tmp = num * 10 / denom;
+	if (tmp % 10 >= 5)
+		pd->iccl = (u_int8_t)((num/denom) + 1);
+	else
+		pd->iccl = (u_int8_t)(num/denom);
+
+	/* Calculate the value for icch. From the data sheet:
+	   icch = (p clock / transfer rate) * (H / (L + H)) */
+	num = peripheral_clk * 4;
+	tmp = num * 10 / denom;
+	if (tmp % 10 >= 5)
+		pd->icch = (u_int8_t)((num/denom) + 1);
+	else
+		pd->icch = (u_int8_t)(num/denom);
+}
+
+static int sh_mobile_i2c_hook_irqs(struct platform_device *dev, int hook)
+{
+	struct resource *res;
+	int ret = -ENXIO;
+	int q, m;
+	int k = 0;
+	int n = 0;
+
+	while ((res = platform_get_resource(dev, IORESOURCE_IRQ, k))) {
+		for (n = res->start; hook && n <= res->end; n++) {
+			if (request_irq(n, sh_mobile_i2c_isr, IRQF_DISABLED,
+					dev->dev.bus_id, dev))
+				goto rollback;
+		}
+		k++;
+	}
+
+	if (hook)
+		return k > 0 ? 0 : -ENOENT;
+
+	k--;
+	ret = 0;
+
+ rollback:
+	for (q = k; k >= 0; k--) {
+		for (m = n; m >= res->start; m--)
+			free_irq(m, dev);
+
+		res = platform_get_resource(dev, IORESOURCE_IRQ, k - 1);
+		m = res->end;
+	}
+
+	return ret;
+}
+
+static int sh_mobile_i2c_probe(struct platform_device *dev)
+{
+	struct sh_mobile_i2c_data *pd;
+	struct i2c_adapter *adap;
+	struct resource *res;
+	int size;
+	int ret;
+
+	pd = kzalloc(sizeof(struct sh_mobile_i2c_data), GFP_KERNEL);
+	if (pd == NULL) {
+		dev_err(&dev->dev, "cannot allocate private data\n");
+		return -ENOMEM;
+	}
+
+	pd->clk = clk_get(&dev->dev, "peripheral_clk");
+	if (IS_ERR(pd->clk)) {
+		dev_err(&dev->dev, "cannot get peripheral clock\n");
+		ret = PTR_ERR(pd->clk);
+		goto err;
+	}
+
+	ret = sh_mobile_i2c_hook_irqs(dev, 1);
+	if (ret) {
+		dev_err(&dev->dev, "cannot request IRQ\n");
+		goto err_clk;
+	}
+
+	pd->dev = &dev->dev;
+	platform_set_drvdata(dev, pd);
+
+	res = platform_get_resource(dev, IORESOURCE_MEM, 0);
+	if (res == NULL) {
+		dev_err(&dev->dev, "cannot find IO resource\n");
+		ret = -ENOENT;
+		goto err_irq;
+	}
+
+	size = (res->end - res->start) + 1;
+
+	pd->reg = ioremap(res->start, size);
+	if (pd->reg == NULL) {
+		dev_err(&dev->dev, "cannot map IO\n");
+		ret = -ENXIO;
+		goto err_irq;
+	}
+
+	/* setup the private data */
+	adap = &pd->adap;
+	i2c_set_adapdata(adap, pd);
+
+	adap->owner = THIS_MODULE;
+	adap->algo = &sh_mobile_i2c_algorithm;
+	adap->dev.parent = &dev->dev;
+	adap->retries = 5;
+	adap->nr = dev->id;
+
+	strlcpy(adap->name, dev->name, sizeof(adap->name));
+
+	sh_mobile_i2c_setup_channel(dev);
+
+	ret = i2c_add_numbered_adapter(adap);
+	if (ret < 0) {
+		dev_err(&dev->dev, "cannot add numbered adapter\n");
+		goto err_all;
+	}
+
+	return 0;
+
+ err_all:
+	iounmap(pd->reg);
+ err_irq:
+	sh_mobile_i2c_hook_irqs(dev, 0);
+ err_clk:
+	clk_put(pd->clk);
+ err:
+	kfree(pd);
+	return ret;
+}
+
+static int sh_mobile_i2c_remove(struct platform_device *dev)
+{
+	struct sh_mobile_i2c_data *pd = platform_get_drvdata(dev);
+
+	i2c_del_adapter(&pd->adap);
+	iounmap(pd->reg);
+	sh_mobile_i2c_hook_irqs(dev, 0);
+	clk_put(pd->clk);
+	kfree(pd);
+	return 0;
+}
+
+static struct platform_driver sh_mobile_i2c_driver = {
+	.driver		= {
+		.name		= "i2c-sh_mobile",
+		.owner		= THIS_MODULE,
+	},
+	.probe		= sh_mobile_i2c_probe,
+	.remove		= sh_mobile_i2c_remove,
+};
+
+static int __init sh_mobile_i2c_adap_init(void)
+{
+	return platform_driver_register(&sh_mobile_i2c_driver);
+}
+
+static void __exit sh_mobile_i2c_adap_exit(void)
+{
+	platform_driver_unregister(&sh_mobile_i2c_driver);
+}
+
+module_init(sh_mobile_i2c_adap_init);
+module_exit(sh_mobile_i2c_adap_exit);
+
+MODULE_DESCRIPTION("SuperH Mobile I2C Bus Controller driver");
+MODULE_AUTHOR("Magnus Damm");
+MODULE_LICENSE("GPL v2");