drivers/i2c/busses/i2c-sh_mobile.c - kernel/panda - Git at Google

 /*
  * 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>

 /* Transmit operation:                                                      */
 /*                                                                          */
 /* 0 byte transmit                                                          */
 /* BUS:     S     A8     ACK   P                                            */
 /* IRQ:       DTE   WAIT                                                    */
 /* ICIC:                                                                    */
 /* ICCR: 0x94 0x90                                                          */
 /* ICDR:      A8                                                            */
 /*                                                                          */
 /* 1 byte transmit                                                          */
 /* BUS:     S     A8     ACK   D8(1)   ACK   P                              */
 /* IRQ:       DTE   WAIT         WAIT                                       */
 /* ICIC:      -DTE                                                          */
 /* ICCR: 0x94       0x90                                                    */
 /* ICDR:      A8    D8(1)                                                   */
 /*                                                                          */
 /* 2 byte transmit                                                          */
 /* BUS:     S     A8     ACK   D8(1)   ACK   D8(2)   ACK   P                */
 /* IRQ:       DTE   WAIT         WAIT          WAIT                         */
 /* ICIC:      -DTE                                                          */
 /* ICCR: 0x94                    0x90                                       */
 /* ICDR:      A8    D8(1)        D8(2)                                      */
 /*                                                                          */
 /* 3 bytes or more, +---------+ gets repeated                               */
 /*                                                                          */
 /*                                                                          */
 /* Receive operation:                                                       */
 /*                                                                          */
 /* 0 byte receive - not supported since slave may hold SDA low              */
 /*                                                                          */
 /* 1 byte receive       [TX] | [RX]                                         */
 /* BUS:     S     A8     ACK | D8(1)   ACK   P                              */
 /* IRQ:       DTE   WAIT     |   WAIT     DTE                               */
 /* ICIC:      -DTE           |   +DTE                                       */
 /* ICCR: 0x94       0x81     |   0xc0                                       */
 /* ICDR:      A8             |            D8(1)                             */
 /*                                                                          */
 /* 2 byte receive        [TX]| [RX]                                         */
 /* BUS:     S     A8     ACK | D8(1)   ACK   D8(2)   ACK   P                */
 /* IRQ:       DTE   WAIT     |   WAIT          WAIT     DTE                 */
 /* ICIC:      -DTE           |                 +DTE                         */
 /* ICCR: 0x94       0x81     |                 0xc0                         */
 /* ICDR:      A8             |                 D8(1)    D8(2)               */
 /*                                                                          */
 /* 3 byte receive       [TX] | [RX]                                         */
 /* BUS:     S     A8     ACK | D8(1)   ACK   D8(2)   ACK   D8(3)   ACK    P */
 /* IRQ:       DTE   WAIT     |   WAIT          WAIT         WAIT      DTE   */
 /* ICIC:      -DTE           |                              +DTE            */
 /* ICCR: 0x94       0x81     |                              0xc0            */
 /* ICDR:      A8             |                 D8(1)        D8(2)     D8(3) */
 /*                                                                          */
 /* 4 bytes or more, this part is repeated    +---------+                    */
 /*                                                                          */
 /*                                                                          */
 /* Interrupt order and BUSY flag                                            */
 /*     ___                                                 _                */
 /* SDA ___\___XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXAAAAAAAAA___/                 */
 /* SCL      \_/1\_/2\_/3\_/4\_/5\_/6\_/7\_/8\___/9\_____/                   */
 /*                                                                          */
 /*        S   D7  D6  D5  D4  D3  D2  D1  D0              P                 */
 /*                                           ___                            */
 /* WAIT IRQ ________________________________/   \___________                */
 /* TACK IRQ ____________________________________/   \_______                */
 /* DTE  IRQ __________________________________________/   \_                */
 /* AL   IRQ XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX                */
 /*         _______________________________________________                  */
 /* BUSY __/                                               \_                */
 /*                                                                          */

 enum sh_mobile_i2c_op {
 	OP_START = 0,
 	OP_TX_FIRST,
 	OP_TX,
 	OP_TX_STOP,
 	OP_TX_TO_RX,
 	OP_RX,
 	OP_RX_STOP,
 	OP_RX_STOP_DATA,
 };

 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: /* issue start and trigger DTE interrupt */
 		iowrite8(0x94, ICCR(pd));
 		break;
 	case OP_TX_FIRST: /* disable DTE interrupt and write data */
 		iowrite8(ICIC_WAITE | ICIC_ALE | ICIC_TACKE, ICIC(pd));
 		iowrite8(data, ICDR(pd));
 		break;
 	case OP_TX: /* write data */
 		iowrite8(data, ICDR(pd));
 		break;
 	case OP_TX_STOP: /* write data and issue a stop afterwards */
 		iowrite8(data, ICDR(pd));
 		iowrite8(0x90, ICCR(pd));
 		break;
 	case OP_TX_TO_RX: /* select read mode */
 		iowrite8(0x81, ICCR(pd));
 		break;
 	case OP_RX: /* just read data */
 		ret = ioread8(ICDR(pd));
 		break;
 	case OP_RX_STOP: /* enable DTE interrupt, issue stop */
 		iowrite8(ICIC_DTEE | ICIC_WAITE | ICIC_ALE | ICIC_TACKE,
 			 ICIC(pd));
 		iowrite8(0xc0, ICCR(pd));
 		break;
 	case OP_RX_STOP_DATA: /* enable DTE interrupt, read data, issue stop */
 		iowrite8(ICIC_DTEE | ICIC_WAITE | ICIC_ALE | ICIC_TACKE,
 			 ICIC(pd));
 		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 int sh_mobile_i2c_is_first_byte(struct sh_mobile_i2c_data *pd)
 {
 	if (pd->pos == -1)
 		return 1;

 	return 0;
 }

 static int sh_mobile_i2c_is_last_byte(struct sh_mobile_i2c_data *pd)
 {
 	if (pd->pos == (pd->msg->len - 1))
 		return 1;

 	return 0;
 }

 static void sh_mobile_i2c_get_data(struct sh_mobile_i2c_data *pd,
 				   unsigned char *buf)
 {
 	switch (pd->pos) {
 	case -1:
 		*buf = (pd->msg->addr & 0x7f) << 1;
 		*buf |= (pd->msg->flags & I2C_M_RD) ? 1 : 0;
 		break;
 	default:
 		*buf = pd->msg->buf[pd->pos];
 	}
 }

 static int sh_mobile_i2c_isr_tx(struct sh_mobile_i2c_data *pd)
 {
 	unsigned char data;

 	if (pd->pos == pd->msg->len)
 		return 1;

 	sh_mobile_i2c_get_data(pd, &data);

 	if (sh_mobile_i2c_is_last_byte(pd))
 		i2c_op(pd, OP_TX_STOP, data);
 	else if (sh_mobile_i2c_is_first_byte(pd))
 		i2c_op(pd, OP_TX_FIRST, data);
 	else
 		i2c_op(pd, OP_TX, data);

 	pd->pos++;
 	return 0;
 }

 static int sh_mobile_i2c_isr_rx(struct sh_mobile_i2c_data *pd)
 {
 	unsigned char data;
 	int real_pos;

 	do {
 		if (pd->pos <= -1) {
 			sh_mobile_i2c_get_data(pd, &data);

 			if (sh_mobile_i2c_is_first_byte(pd))
 				i2c_op(pd, OP_TX_FIRST, data);
 			else
 				i2c_op(pd, OP_TX, data);
 			break;
 		}

 		if (pd->pos == 0) {
 			i2c_op(pd, OP_TX_TO_RX, 0);
 			break;
 		}

 		real_pos = pd->pos - 2;

 		if (pd->pos == pd->msg->len) {
 			if (real_pos < 0) {
 				i2c_op(pd, OP_RX_STOP, 0);
 				break;
 			}
 			data = i2c_op(pd, OP_RX_STOP_DATA, 0);
 		} else
 			data = i2c_op(pd, OP_RX, 0);

 		if (real_pos >= 0)
 			pd->msg->buf[real_pos] = data;
 	} while (0);

 	pd->pos++;
 	return pd->pos == (pd->msg->len + 2);
 }

 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);
 	unsigned char sr;
 	int wakeup;

 	sr = ioread8(ICSR(pd));
 	pd->sr |= sr; /* remember state */

 	dev_dbg(pd->dev, "i2c_isr 0x%02x 0x%02x %s %d %d!\n", sr, pd->sr,
 	       (pd->msg->flags & I2C_M_RD) ? "read" : "write",
 	       pd->pos, pd->msg->len);

 	if (sr & (ICSR_AL | ICSR_TACK)) {
 		/* don't interrupt transaction - continue to issue stop */
 		iowrite8(sr & ~(ICSR_AL | ICSR_TACK), ICSR(pd));
 		wakeup = 0;
 	} else if (pd->msg->flags & I2C_M_RD)
 		wakeup = sh_mobile_i2c_isr_rx(pd);
 	else
 		wakeup = sh_mobile_i2c_isr_tx(pd);

 	if (sr & ICSR_WAIT) /* TODO: add delay here to support slow acks */
 		iowrite8(sr & ~ICSR_WAIT, ICSR(pd));

 	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)
 {
 	if (usr_msg->len == 0 && (usr_msg->flags & I2C_M_RD)) {
 		dev_err(pd->dev, "Unsupported zero length i2c read\n");
 		return -EIO;
 	}

 	/* 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 to begin with */
 	iowrite8(ICIC_WAITE | 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 = 1000;
 again:
 		val = ioread8(ICSR(pd));

 		dev_dbg(pd->dev, "val 0x%02x pd->sr 0x%02x\n", val, pd->sr);

 		/* the interrupt handler may wake us up before the
 		 * transfer is finished, so poll the hardware
 		 * until we're done.
 		 */
 		if (val & ICSR_BUSY) {
 			udelay(10);
 			if (retry_count--)
 				goto again;

 			err = -EIO;
 			dev_err(pd->dev, "Polling timed out\n");
 			break;
 		}

 		/* handle missing acknowledge and arbitration lost */
 		if ((val | pd->sr) & (ICSR_TACK | ICSR_AL)) {
 			err = -EIO;
 			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");
	/*
	* 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>

	/* Transmit operation: */
	/* */
	/* 0 byte transmit */
	/* BUS: S A8 ACK P */
	/* IRQ: DTE WAIT */
	/* ICIC: */
	/* ICCR: 0x94 0x90 */
	/* ICDR: A8 */
	/* */
	/* 1 byte transmit */
	/* BUS: S A8 ACK D8(1) ACK P */
	/* IRQ: DTE WAIT WAIT */
	/* ICIC: -DTE */
	/* ICCR: 0x94 0x90 */
	/* ICDR: A8 D8(1) */
	/* */
	/* 2 byte transmit */
	/* BUS: S A8 ACK D8(1) ACK D8(2) ACK P */
	/* IRQ: DTE WAIT WAIT WAIT */
	/* ICIC: -DTE */
	/* ICCR: 0x94 0x90 */
	/* ICDR: A8 D8(1) D8(2) */
	/* */
	/* 3 bytes or more, +---------+ gets repeated */
	/* */
	/* */
	/* Receive operation: */
	/* */
	/* 0 byte receive - not supported since slave may hold SDA low */
	/* */
	/* 1 byte receive [TX] \| [RX] */
	/* BUS: S A8 ACK \| D8(1) ACK P */
	/* IRQ: DTE WAIT \| WAIT DTE */
	/* ICIC: -DTE \| +DTE */
	/* ICCR: 0x94 0x81 \| 0xc0 */
	/* ICDR: A8 \| D8(1) */
	/* */
	/* 2 byte receive [TX]\| [RX] */
	/* BUS: S A8 ACK \| D8(1) ACK D8(2) ACK P */
	/* IRQ: DTE WAIT \| WAIT WAIT DTE */
	/* ICIC: -DTE \| +DTE */
	/* ICCR: 0x94 0x81 \| 0xc0 */
	/* ICDR: A8 \| D8(1) D8(2) */
	/* */
	/* 3 byte receive [TX] \| [RX] */
	/* BUS: S A8 ACK \| D8(1) ACK D8(2) ACK D8(3) ACK P */
	/* IRQ: DTE WAIT \| WAIT WAIT WAIT DTE */
	/* ICIC: -DTE \| +DTE */
	/* ICCR: 0x94 0x81 \| 0xc0 */
	/* ICDR: A8 \| D8(1) D8(2) D8(3) */
	/* */
	/* 4 bytes or more, this part is repeated +---------+ */
	/* */
	/* */
	/* Interrupt order and BUSY flag */
	/* ___ _ */
	/* SDA ___\___XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXAAAAAAAAA___/ */
	/* SCL \_/1\_/2\_/3\_/4\_/5\_/6\_/7\_/8\___/9\_____/ */
	/* */
	/* S D7 D6 D5 D4 D3 D2 D1 D0 P */
	/* ___ */
	/* WAIT IRQ ________________________________/ \___________ */
	/* TACK IRQ ____________________________________/ \_______ */
	/* DTE IRQ __________________________________________/ \_ */
	/* AL IRQ XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX */
	/* _______________________________________________ */
	/* BUSY __/ \_ */
	/* */

	enum sh_mobile_i2c_op {
	OP_START = 0,
	OP_TX_FIRST,
	OP_TX,
	OP_TX_STOP,
	OP_TX_TO_RX,
	OP_RX,
	OP_RX_STOP,
	OP_RX_STOP_DATA,
	};

	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: /* issue start and trigger DTE interrupt */
	iowrite8(0x94, ICCR(pd));
	break;
	case OP_TX_FIRST: /* disable DTE interrupt and write data */
	iowrite8(ICIC_WAITE \| ICIC_ALE \| ICIC_TACKE, ICIC(pd));
	iowrite8(data, ICDR(pd));
	break;
	case OP_TX: /* write data */
	iowrite8(data, ICDR(pd));
	break;
	case OP_TX_STOP: /* write data and issue a stop afterwards */
	iowrite8(data, ICDR(pd));
	iowrite8(0x90, ICCR(pd));
	break;
	case OP_TX_TO_RX: /* select read mode */
	iowrite8(0x81, ICCR(pd));
	break;
	case OP_RX: /* just read data */
	ret = ioread8(ICDR(pd));
	break;
	case OP_RX_STOP: /* enable DTE interrupt, issue stop */
	iowrite8(ICIC_DTEE \| ICIC_WAITE \| ICIC_ALE \| ICIC_TACKE,
	ICIC(pd));
	iowrite8(0xc0, ICCR(pd));
	break;
	case OP_RX_STOP_DATA: /* enable DTE interrupt, read data, issue stop */
	iowrite8(ICIC_DTEE \| ICIC_WAITE \| ICIC_ALE \| ICIC_TACKE,
	ICIC(pd));
	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 int sh_mobile_i2c_is_first_byte(struct sh_mobile_i2c_data *pd)
	{
	if (pd->pos == -1)
	return 1;

	return 0;
	}

	static int sh_mobile_i2c_is_last_byte(struct sh_mobile_i2c_data *pd)
	{
	if (pd->pos == (pd->msg->len - 1))
	return 1;

	return 0;
	}

	static void sh_mobile_i2c_get_data(struct sh_mobile_i2c_data *pd,
	unsigned char *buf)
	{
	switch (pd->pos) {
	case -1:
	*buf = (pd->msg->addr & 0x7f) << 1;
	*buf \|= (pd->msg->flags & I2C_M_RD) ? 1 : 0;
	break;
	default:
	*buf = pd->msg->buf[pd->pos];
	}
	}

	static int sh_mobile_i2c_isr_tx(struct sh_mobile_i2c_data *pd)
	{
	unsigned char data;

	if (pd->pos == pd->msg->len)
	return 1;

	sh_mobile_i2c_get_data(pd, &data);

	if (sh_mobile_i2c_is_last_byte(pd))
	i2c_op(pd, OP_TX_STOP, data);
	else if (sh_mobile_i2c_is_first_byte(pd))
	i2c_op(pd, OP_TX_FIRST, data);
	else
	i2c_op(pd, OP_TX, data);

	pd->pos++;
	return 0;
	}

	static int sh_mobile_i2c_isr_rx(struct sh_mobile_i2c_data *pd)
	{
	unsigned char data;
	int real_pos;

	do {
	if (pd->pos <= -1) {
	sh_mobile_i2c_get_data(pd, &data);

	if (sh_mobile_i2c_is_first_byte(pd))
	i2c_op(pd, OP_TX_FIRST, data);
	else
	i2c_op(pd, OP_TX, data);
	break;
	}

	if (pd->pos == 0) {
	i2c_op(pd, OP_TX_TO_RX, 0);
	break;
	}

	real_pos = pd->pos - 2;

	if (pd->pos == pd->msg->len) {
	if (real_pos < 0) {
	i2c_op(pd, OP_RX_STOP, 0);
	break;
	}
	data = i2c_op(pd, OP_RX_STOP_DATA, 0);
	} else
	data = i2c_op(pd, OP_RX, 0);

	if (real_pos >= 0)
	pd->msg->buf[real_pos] = data;
	} while (0);

	pd->pos++;
	return pd->pos == (pd->msg->len + 2);
	}

	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);
	unsigned char sr;
	int wakeup;

	sr = ioread8(ICSR(pd));
	pd->sr \|= sr; /* remember state */

	dev_dbg(pd->dev, "i2c_isr 0x%02x 0x%02x %s %d %d!\n", sr, pd->sr,
	(pd->msg->flags & I2C_M_RD) ? "read" : "write",
	pd->pos, pd->msg->len);

	if (sr & (ICSR_AL \| ICSR_TACK)) {
	/* don't interrupt transaction - continue to issue stop */
	iowrite8(sr & ~(ICSR_AL \| ICSR_TACK), ICSR(pd));
	wakeup = 0;
	} else if (pd->msg->flags & I2C_M_RD)
	wakeup = sh_mobile_i2c_isr_rx(pd);
	else
	wakeup = sh_mobile_i2c_isr_tx(pd);

	if (sr & ICSR_WAIT) /* TODO: add delay here to support slow acks */
	iowrite8(sr & ~ICSR_WAIT, ICSR(pd));

	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)
	{
	if (usr_msg->len == 0 && (usr_msg->flags & I2C_M_RD)) {
	dev_err(pd->dev, "Unsupported zero length i2c read\n");
	return -EIO;
	}

	/* 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 to begin with */
	iowrite8(ICIC_WAITE \| 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 = 1000;
	again:
	val = ioread8(ICSR(pd));

	dev_dbg(pd->dev, "val 0x%02x pd->sr 0x%02x\n", val, pd->sr);

	/* the interrupt handler may wake us up before the
	* transfer is finished, so poll the hardware
	* until we're done.
	*/
	if (val & ICSR_BUSY) {
	udelay(10);
	if (retry_count--)
	goto again;

	err = -EIO;
	dev_err(pd->dev, "Polling timed out\n");
	break;
	}

	/* handle missing acknowledge and arbitration lost */
	if ((val \| pd->sr) & (ICSR_TACK \| ICSR_AL)) {
	err = -EIO;
	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");