drivers/i2c/busses/i2c-rcar.c - kernel/msm-4.19 - Gitiles

 /*
  * Driver for the Renesas RCar I2C unit
  *
  * Copyright (C) 2014 Wolfram Sang <wsa@sang-engineering.com>
  *
  * Copyright (C) 2012-14 Renesas Solutions Corp.
  * Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
  *
  * This file is based on the drivers/i2c/busses/i2c-sh7760.c
  * (c) 2005-2008 MSC Vertriebsges.m.b.H, Manuel Lauss <mlau@msc-ge.com>
  *
  * This file used out-of-tree driver i2c-rcar.c
  * Copyright (C) 2011-2012 Renesas Electronics Corporation
  *
  * 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; 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.
  */
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/i2c.h>
 #include <linux/i2c/i2c-rcar.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>

 /* register offsets */
 #define ICSCR	0x00	/* slave ctrl */
 #define ICMCR	0x04	/* master ctrl */
 #define ICSSR	0x08	/* slave status */
 #define ICMSR	0x0C	/* master status */
 #define ICSIER	0x10	/* slave irq enable */
 #define ICMIER	0x14	/* master irq enable */
 #define ICCCR	0x18	/* clock dividers */
 #define ICSAR	0x1C	/* slave address */
 #define ICMAR	0x20	/* master address */
 #define ICRXTX	0x24	/* data port */

 /* ICMCR */
 #define MDBS	(1 << 7)	/* non-fifo mode switch */
 #define FSCL	(1 << 6)	/* override SCL pin */
 #define FSDA	(1 << 5)	/* override SDA pin */
 #define OBPC	(1 << 4)	/* override pins */
 #define MIE	(1 << 3)	/* master if enable */
 #define TSBE	(1 << 2)
 #define FSB	(1 << 1)	/* force stop bit */
 #define ESG	(1 << 0)	/* en startbit gen */

 /* ICMSR (also for ICMIE) */
 #define MNR	(1 << 6)	/* nack received */
 #define MAL	(1 << 5)	/* arbitration lost */
 #define MST	(1 << 4)	/* sent a stop */
 #define MDE	(1 << 3)
 #define MDT	(1 << 2)
 #define MDR	(1 << 1)
 #define MAT	(1 << 0)	/* slave addr xfer done */


 #define RCAR_BUS_PHASE_START	(MDBS | MIE | ESG)
 #define RCAR_BUS_PHASE_DATA	(MDBS | MIE)
 #define RCAR_BUS_PHASE_STOP	(MDBS | MIE | FSB)

 #define RCAR_IRQ_SEND	(MNR | MAL | MST | MAT | MDE)
 #define RCAR_IRQ_RECV	(MNR | MAL | MST | MAT | MDR)
 #define RCAR_IRQ_STOP	(MST)

 #define RCAR_IRQ_ACK_SEND	(~(MAT | MDE) & 0xFF)
 #define RCAR_IRQ_ACK_RECV	(~(MAT | MDR) & 0xFF)

 #define ID_LAST_MSG	(1 << 0)
 #define ID_IOERROR	(1 << 1)
 #define ID_DONE		(1 << 2)
 #define ID_ARBLOST	(1 << 3)
 #define ID_NACK		(1 << 4)

 enum rcar_i2c_type {
 	I2C_RCAR_GEN1,
 	I2C_RCAR_GEN2,
 };

 struct rcar_i2c_priv {
 	void __iomem *io;
 	struct i2c_adapter adap;
 	struct i2c_msg	*msg;
 	struct clk *clk;

 	spinlock_t lock;
 	wait_queue_head_t wait;

 	int pos;
 	u32 icccr;
 	u32 flags;
 	enum rcar_i2c_type devtype;
 };

 #define rcar_i2c_priv_to_dev(p)		((p)->adap.dev.parent)
 #define rcar_i2c_is_recv(p)		((p)->msg->flags & I2C_M_RD)

 #define rcar_i2c_flags_set(p, f)	((p)->flags |= (f))
 #define rcar_i2c_flags_has(p, f)	((p)->flags & (f))

 #define LOOP_TIMEOUT	1024


 static void rcar_i2c_write(struct rcar_i2c_priv *priv, int reg, u32 val)
 {
 	writel(val, priv->io + reg);
 }

 static u32 rcar_i2c_read(struct rcar_i2c_priv *priv, int reg)
 {
 	return readl(priv->io + reg);
 }

 static void rcar_i2c_init(struct rcar_i2c_priv *priv)
 {
 	/*
 	 * reset slave mode.
 	 * slave mode is not used on this driver
 	 */
 	rcar_i2c_write(priv, ICSIER, 0);
 	rcar_i2c_write(priv, ICSAR, 0);
 	rcar_i2c_write(priv, ICSCR, 0);
 	rcar_i2c_write(priv, ICSSR, 0);

 	/* reset master mode */
 	rcar_i2c_write(priv, ICMIER, 0);
 	rcar_i2c_write(priv, ICMCR, 0);
 	rcar_i2c_write(priv, ICMSR, 0);
 	rcar_i2c_write(priv, ICMAR, 0);
 }

 static int rcar_i2c_bus_barrier(struct rcar_i2c_priv *priv)
 {
 	int i;

 	for (i = 0; i < LOOP_TIMEOUT; i++) {
 		/* make sure that bus is not busy */
 		if (!(rcar_i2c_read(priv, ICMCR) & FSDA))
 			return 0;
 		udelay(1);
 	}

 	return -EBUSY;
 }

 static int rcar_i2c_clock_calculate(struct rcar_i2c_priv *priv,
 				    u32 bus_speed,
 				    struct device *dev)
 {
 	u32 scgd, cdf;
 	u32 round, ick;
 	u32 scl;
 	u32 cdf_width;
 	unsigned long rate;

 	switch (priv->devtype) {
 	case I2C_RCAR_GEN1:
 		cdf_width = 2;
 		break;
 	case I2C_RCAR_GEN2:
 		cdf_width = 3;
 		break;
 	default:
 		dev_err(dev, "device type error\n");
 		return -EIO;
 	}

 	/*
 	 * calculate SCL clock
 	 * see
 	 *	ICCCR
 	 *
 	 * ick	= clkp / (1 + CDF)
 	 * SCL	= ick / (20 + SCGD * 8 + F[(ticf + tr + intd) * ick])
 	 *
 	 * ick  : I2C internal clock < 20 MHz
 	 * ticf : I2C SCL falling time  =  35 ns here
 	 * tr   : I2C SCL rising  time  = 200 ns here
 	 * intd : LSI internal delay    =  50 ns here
 	 * clkp : peripheral_clk
 	 * F[]  : integer up-valuation
 	 */
 	rate = clk_get_rate(priv->clk);
 	cdf = rate / 20000000;
 	if (cdf >= 1 << cdf_width) {
 		dev_err(dev, "Input clock %lu too high\n", rate);
 		return -EIO;
 	}
 	ick = rate / (cdf + 1);

 	/*
 	 * it is impossible to calculate large scale
 	 * number on u32. separate it
 	 *
 	 * F[(ticf + tr + intd) * ick]
 	 *  = F[(35 + 200 + 50)ns * ick]
 	 *  = F[285 * ick / 1000000000]
 	 *  = F[(ick / 1000000) * 285 / 1000]
 	 */
 	round = (ick + 500000) / 1000000 * 285;
 	round = (round + 500) / 1000;

 	/*
 	 * SCL	= ick / (20 + SCGD * 8 + F[(ticf + tr + intd) * ick])
 	 *
 	 * Calculation result (= SCL) should be less than
 	 * bus_speed for hardware safety
 	 *
 	 * We could use something along the lines of
 	 *	div = ick / (bus_speed + 1) + 1;
 	 *	scgd = (div - 20 - round + 7) / 8;
 	 *	scl = ick / (20 + (scgd * 8) + round);
 	 * (not fully verified) but that would get pretty involved
 	 */
 	for (scgd = 0; scgd < 0x40; scgd++) {
 		scl = ick / (20 + (scgd * 8) + round);
 		if (scl <= bus_speed)
 			goto scgd_find;
 	}
 	dev_err(dev, "it is impossible to calculate best SCL\n");
 	return -EIO;

 scgd_find:
 	dev_dbg(dev, "clk %d/%d(%lu), round %u, CDF:0x%x, SCGD: 0x%x\n",
 		scl, bus_speed, clk_get_rate(priv->clk), round, cdf, scgd);

 	/*
 	 * keep icccr value
 	 */
 	priv->icccr = scgd << cdf_width | cdf;

 	return 0;
 }

 static int rcar_i2c_prepare_msg(struct rcar_i2c_priv *priv)
 {
 	int read = !!rcar_i2c_is_recv(priv);

 	rcar_i2c_write(priv, ICMAR, (priv->msg->addr << 1) | read);
 	rcar_i2c_write(priv, ICMSR, 0);
 	rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_START);
 	rcar_i2c_write(priv, ICMIER, read ? RCAR_IRQ_RECV : RCAR_IRQ_SEND);

 	return 0;
 }

 /*
  *		interrupt functions
  */
 static int rcar_i2c_irq_send(struct rcar_i2c_priv *priv, u32 msr)
 {
 	struct i2c_msg *msg = priv->msg;

 	/*
 	 * FIXME
 	 * sometimes, unknown interrupt happened.
 	 * Do nothing
 	 */
 	if (!(msr & MDE))
 		return 0;

 	/*
 	 * If address transfer phase finished,
 	 * goto data phase.
 	 */
 	if (msr & MAT)
 		rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_DATA);

 	if (priv->pos < msg->len) {
 		/*
 		 * Prepare next data to ICRXTX register.
 		 * This data will go to _SHIFT_ register.
 		 *
 		 *    *
 		 * [ICRXTX] -> [SHIFT] -> [I2C bus]
 		 */
 		rcar_i2c_write(priv, ICRXTX, msg->buf[priv->pos]);
 		priv->pos++;

 	} else {
 		/*
 		 * The last data was pushed to ICRXTX on _PREV_ empty irq.
 		 * It is on _SHIFT_ register, and will sent to I2C bus.
 		 *
 		 *		  *
 		 * [ICRXTX] -> [SHIFT] -> [I2C bus]
 		 */

 		if (priv->flags & ID_LAST_MSG)
 			/*
 			 * If current msg is the _LAST_ msg,
 			 * prepare stop condition here.
 			 * ID_DONE will be set on STOP irq.
 			 */
 			rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_STOP);
 		else
 			/*
 			 * If current msg is _NOT_ last msg,
 			 * it doesn't call stop phase.
 			 * thus, there is no STOP irq.
 			 * return ID_DONE here.
 			 */
 			return ID_DONE;
 	}

 	rcar_i2c_write(priv, ICMSR, RCAR_IRQ_ACK_SEND);

 	return 0;
 }

 static int rcar_i2c_irq_recv(struct rcar_i2c_priv *priv, u32 msr)
 {
 	struct i2c_msg *msg = priv->msg;

 	/*
 	 * FIXME
 	 * sometimes, unknown interrupt happened.
 	 * Do nothing
 	 */
 	if (!(msr & MDR))
 		return 0;

 	if (msr & MAT) {
 		/*
 		 * Address transfer phase finished,
 		 * but, there is no data at this point.
 		 * Do nothing.
 		 */
 	} else if (priv->pos < msg->len) {
 		/*
 		 * get received data
 		 */
 		msg->buf[priv->pos] = rcar_i2c_read(priv, ICRXTX);
 		priv->pos++;
 	}

 	/*
 	 * If next received data is the _LAST_,
 	 * go to STOP phase,
 	 * otherwise, go to DATA phase.
 	 */
 	if (priv->pos + 1 >= msg->len)
 		rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_STOP);
 	else
 		rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_DATA);

 	rcar_i2c_write(priv, ICMSR, RCAR_IRQ_ACK_RECV);

 	return 0;
 }

 static irqreturn_t rcar_i2c_irq(int irq, void *ptr)
 {
 	struct rcar_i2c_priv *priv = ptr;
 	u32 msr;

 	/*-------------- spin lock -----------------*/
 	spin_lock(&priv->lock);

 	msr = rcar_i2c_read(priv, ICMSR);

 	/* Only handle interrupts that are currently enabled */
 	msr &= rcar_i2c_read(priv, ICMIER);

 	/* Arbitration lost */
 	if (msr & MAL) {
 		rcar_i2c_flags_set(priv, (ID_DONE | ID_ARBLOST));
 		goto out;
 	}

 	/* Nack */
 	if (msr & MNR) {
 		/* go to stop phase */
 		rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_STOP);
 		rcar_i2c_write(priv, ICMIER, RCAR_IRQ_STOP);
 		rcar_i2c_flags_set(priv, ID_NACK);
 		goto out;
 	}

 	/* Stop */
 	if (msr & MST) {
 		rcar_i2c_flags_set(priv, ID_DONE);
 		goto out;
 	}

 	if (rcar_i2c_is_recv(priv))
 		rcar_i2c_flags_set(priv, rcar_i2c_irq_recv(priv, msr));
 	else
 		rcar_i2c_flags_set(priv, rcar_i2c_irq_send(priv, msr));

 out:
 	if (rcar_i2c_flags_has(priv, ID_DONE)) {
 		rcar_i2c_write(priv, ICMIER, 0);
 		rcar_i2c_write(priv, ICMSR, 0);
 		wake_up(&priv->wait);
 	}

 	spin_unlock(&priv->lock);
 	/*-------------- spin unlock -----------------*/

 	return IRQ_HANDLED;
 }

 static int rcar_i2c_master_xfer(struct i2c_adapter *adap,
 				struct i2c_msg *msgs,
 				int num)
 {
 	struct rcar_i2c_priv *priv = i2c_get_adapdata(adap);
 	struct device *dev = rcar_i2c_priv_to_dev(priv);
 	unsigned long flags;
 	int i, ret, timeout;

 	pm_runtime_get_sync(dev);

 	/*-------------- spin lock -----------------*/
 	spin_lock_irqsave(&priv->lock, flags);

 	rcar_i2c_init(priv);
 	/* start clock */
 	rcar_i2c_write(priv, ICCCR, priv->icccr);

 	spin_unlock_irqrestore(&priv->lock, flags);
 	/*-------------- spin unlock -----------------*/

 	ret = rcar_i2c_bus_barrier(priv);
 	if (ret < 0)
 		goto out;

 	for (i = 0; i < num; i++) {
 		/* This HW can't send STOP after address phase */
 		if (msgs[i].len == 0) {
 			ret = -EOPNOTSUPP;
 			break;
 		}

 		/*-------------- spin lock -----------------*/
 		spin_lock_irqsave(&priv->lock, flags);

 		/* init each data */
 		priv->msg	= &msgs[i];
 		priv->pos	= 0;
 		priv->flags	= 0;
 		if (priv->msg == &msgs[num - 1])
 			rcar_i2c_flags_set(priv, ID_LAST_MSG);

 		ret = rcar_i2c_prepare_msg(priv);

 		spin_unlock_irqrestore(&priv->lock, flags);
 		/*-------------- spin unlock -----------------*/

 		if (ret < 0)
 			break;

 		timeout = wait_event_timeout(priv->wait,
 					     rcar_i2c_flags_has(priv, ID_DONE),
 					     5 * HZ);
 		if (!timeout) {
 			ret = -ETIMEDOUT;
 			break;
 		}

 		if (rcar_i2c_flags_has(priv, ID_NACK)) {
 			ret = -ENXIO;
 			break;
 		}

 		if (rcar_i2c_flags_has(priv, ID_ARBLOST)) {
 			ret = -EAGAIN;
 			break;
 		}

 		if (rcar_i2c_flags_has(priv, ID_IOERROR)) {
 			ret = -EIO;
 			break;
 		}

 		ret = i + 1; /* The number of transfer */
 	}
 out:
 	pm_runtime_put(dev);

 	if (ret < 0 && ret != -ENXIO)
 		dev_err(dev, "error %d : %x\n", ret, priv->flags);

 	return ret;
 }

 static u32 rcar_i2c_func(struct i2c_adapter *adap)
 {
 	/* This HW can't do SMBUS_QUICK and NOSTART */
 	return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
 }

 static const struct i2c_algorithm rcar_i2c_algo = {
 	.master_xfer	= rcar_i2c_master_xfer,
 	.functionality	= rcar_i2c_func,
 };

 static const struct of_device_id rcar_i2c_dt_ids[] = {
 	{ .compatible = "renesas,i2c-rcar", .data = (void *)I2C_RCAR_GEN1 },
 	{ .compatible = "renesas,i2c-r8a7778", .data = (void *)I2C_RCAR_GEN1 },
 	{ .compatible = "renesas,i2c-r8a7779", .data = (void *)I2C_RCAR_GEN1 },
 	{ .compatible = "renesas,i2c-r8a7790", .data = (void *)I2C_RCAR_GEN2 },
 	{ .compatible = "renesas,i2c-r8a7791", .data = (void *)I2C_RCAR_GEN2 },
 	{ .compatible = "renesas,i2c-r8a7792", .data = (void *)I2C_RCAR_GEN2 },
 	{ .compatible = "renesas,i2c-r8a7793", .data = (void *)I2C_RCAR_GEN2 },
 	{ .compatible = "renesas,i2c-r8a7794", .data = (void *)I2C_RCAR_GEN2 },
 	{},
 };
 MODULE_DEVICE_TABLE(of, rcar_i2c_dt_ids);

 static int rcar_i2c_probe(struct platform_device *pdev)
 {
 	struct i2c_rcar_platform_data *pdata = dev_get_platdata(&pdev->dev);
 	struct rcar_i2c_priv *priv;
 	struct i2c_adapter *adap;
 	struct resource *res;
 	struct device *dev = &pdev->dev;
 	u32 bus_speed;
 	int irq, ret;

 	priv = devm_kzalloc(dev, sizeof(struct rcar_i2c_priv), GFP_KERNEL);
 	if (!priv)
 		return -ENOMEM;

 	priv->clk = devm_clk_get(dev, NULL);
 	if (IS_ERR(priv->clk)) {
 		dev_err(dev, "cannot get clock\n");
 		return PTR_ERR(priv->clk);
 	}

 	bus_speed = 100000; /* default 100 kHz */
 	ret = of_property_read_u32(dev->of_node, "clock-frequency", &bus_speed);
 	if (ret < 0 && pdata && pdata->bus_speed)
 		bus_speed = pdata->bus_speed;

 	if (pdev->dev.of_node)
 		priv->devtype = (long)of_match_device(rcar_i2c_dt_ids,
 						      dev)->data;
 	else
 		priv->devtype = platform_get_device_id(pdev)->driver_data;

 	ret = rcar_i2c_clock_calculate(priv, bus_speed, dev);
 	if (ret < 0)
 		return ret;

 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	priv->io = devm_ioremap_resource(dev, res);
 	if (IS_ERR(priv->io))
 		return PTR_ERR(priv->io);

 	irq = platform_get_irq(pdev, 0);
 	init_waitqueue_head(&priv->wait);
 	spin_lock_init(&priv->lock);

 	adap = &priv->adap;
 	adap->nr = pdev->id;
 	adap->algo = &rcar_i2c_algo;
 	adap->class = I2C_CLASS_DEPRECATED;
 	adap->retries = 3;
 	adap->dev.parent = dev;
 	adap->dev.of_node = dev->of_node;
 	i2c_set_adapdata(adap, priv);
 	strlcpy(adap->name, pdev->name, sizeof(adap->name));

 	ret = devm_request_irq(dev, irq, rcar_i2c_irq, 0,
 			       dev_name(dev), priv);
 	if (ret < 0) {
 		dev_err(dev, "cannot get irq %d\n", irq);
 		return ret;
 	}

 	ret = i2c_add_numbered_adapter(adap);
 	if (ret < 0) {
 		dev_err(dev, "reg adap failed: %d\n", ret);
 		return ret;
 	}

 	pm_runtime_enable(dev);
 	platform_set_drvdata(pdev, priv);

 	dev_info(dev, "probed\n");

 	return 0;
 }

 static int rcar_i2c_remove(struct platform_device *pdev)
 {
 	struct rcar_i2c_priv *priv = platform_get_drvdata(pdev);
 	struct device *dev = &pdev->dev;

 	i2c_del_adapter(&priv->adap);
 	pm_runtime_disable(dev);

 	return 0;
 }

 static struct platform_device_id rcar_i2c_id_table[] = {
 	{ "i2c-rcar",		I2C_RCAR_GEN1 },
 	{ "i2c-rcar_gen1",	I2C_RCAR_GEN1 },
 	{ "i2c-rcar_gen2",	I2C_RCAR_GEN2 },
 	{},
 };
 MODULE_DEVICE_TABLE(platform, rcar_i2c_id_table);

 static struct platform_driver rcar_i2c_driver = {
 	.driver	= {
 		.name	= "i2c-rcar",
 		.owner	= THIS_MODULE,
 		.of_match_table = rcar_i2c_dt_ids,
 	},
 	.probe		= rcar_i2c_probe,
 	.remove		= rcar_i2c_remove,
 	.id_table	= rcar_i2c_id_table,
 };

 module_platform_driver(rcar_i2c_driver);

 MODULE_LICENSE("GPL v2");
 MODULE_DESCRIPTION("Renesas R-Car I2C bus driver");
 MODULE_AUTHOR("Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>");
	/*
	* Driver for the Renesas RCar I2C unit
	*
	* Copyright (C) 2014 Wolfram Sang <wsa@sang-engineering.com>
	*
	* Copyright (C) 2012-14 Renesas Solutions Corp.
	* Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
	*
	* This file is based on the drivers/i2c/busses/i2c-sh7760.c
	* (c) 2005-2008 MSC Vertriebsges.m.b.H, Manuel Lauss <mlau@msc-ge.com>
	*
	* This file used out-of-tree driver i2c-rcar.c
	* Copyright (C) 2011-2012 Renesas Electronics Corporation
	*
	* 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; 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.
	*/
	#include <linux/clk.h>
	#include <linux/delay.h>
	#include <linux/err.h>
	#include <linux/interrupt.h>
	#include <linux/io.h>
	#include <linux/i2c.h>
	#include <linux/i2c/i2c-rcar.h>
	#include <linux/kernel.h>
	#include <linux/module.h>
	#include <linux/of_device.h>
	#include <linux/platform_device.h>
	#include <linux/pm_runtime.h>
	#include <linux/slab.h>
	#include <linux/spinlock.h>

	/* register offsets */
	#define ICSCR 0x00 /* slave ctrl */
	#define ICMCR 0x04 /* master ctrl */
	#define ICSSR 0x08 /* slave status */
	#define ICMSR 0x0C /* master status */
	#define ICSIER 0x10 /* slave irq enable */
	#define ICMIER 0x14 /* master irq enable */
	#define ICCCR 0x18 /* clock dividers */
	#define ICSAR 0x1C /* slave address */
	#define ICMAR 0x20 /* master address */
	#define ICRXTX 0x24 /* data port */

	/* ICMCR */
	#define MDBS (1 << 7) /* non-fifo mode switch */
	#define FSCL (1 << 6) /* override SCL pin */
	#define FSDA (1 << 5) /* override SDA pin */
	#define OBPC (1 << 4) /* override pins */
	#define MIE (1 << 3) /* master if enable */
	#define TSBE (1 << 2)
	#define FSB (1 << 1) /* force stop bit */
	#define ESG (1 << 0) /* en startbit gen */

	/* ICMSR (also for ICMIE) */
	#define MNR (1 << 6) /* nack received */
	#define MAL (1 << 5) /* arbitration lost */
	#define MST (1 << 4) /* sent a stop */
	#define MDE (1 << 3)
	#define MDT (1 << 2)
	#define MDR (1 << 1)
	#define MAT (1 << 0) /* slave addr xfer done */


	#define RCAR_BUS_PHASE_START (MDBS \| MIE \| ESG)
	#define RCAR_BUS_PHASE_DATA (MDBS \| MIE)
	#define RCAR_BUS_PHASE_STOP (MDBS \| MIE \| FSB)

	#define RCAR_IRQ_SEND (MNR \| MAL \| MST \| MAT \| MDE)
	#define RCAR_IRQ_RECV (MNR \| MAL \| MST \| MAT \| MDR)
	#define RCAR_IRQ_STOP (MST)

	#define RCAR_IRQ_ACK_SEND (~(MAT \| MDE) & 0xFF)
	#define RCAR_IRQ_ACK_RECV (~(MAT \| MDR) & 0xFF)

	#define ID_LAST_MSG (1 << 0)
	#define ID_IOERROR (1 << 1)
	#define ID_DONE (1 << 2)
	#define ID_ARBLOST (1 << 3)
	#define ID_NACK (1 << 4)

	enum rcar_i2c_type {
	I2C_RCAR_GEN1,
	I2C_RCAR_GEN2,
	};

	struct rcar_i2c_priv {
	void __iomem *io;
	struct i2c_adapter adap;
	struct i2c_msg *msg;
	struct clk *clk;

	spinlock_t lock;
	wait_queue_head_t wait;

	int pos;
	u32 icccr;
	u32 flags;
	enum rcar_i2c_type devtype;
	};

	#define rcar_i2c_priv_to_dev(p) ((p)->adap.dev.parent)
	#define rcar_i2c_is_recv(p) ((p)->msg->flags & I2C_M_RD)

	#define rcar_i2c_flags_set(p, f) ((p)->flags \|= (f))
	#define rcar_i2c_flags_has(p, f) ((p)->flags & (f))

	#define LOOP_TIMEOUT 1024


	static void rcar_i2c_write(struct rcar_i2c_priv *priv, int reg, u32 val)
	{
	writel(val, priv->io + reg);
	}

	static u32 rcar_i2c_read(struct rcar_i2c_priv *priv, int reg)
	{
	return readl(priv->io + reg);
	}

	static void rcar_i2c_init(struct rcar_i2c_priv *priv)
	{
	/*
	* reset slave mode.
	* slave mode is not used on this driver
	*/
	rcar_i2c_write(priv, ICSIER, 0);
	rcar_i2c_write(priv, ICSAR, 0);
	rcar_i2c_write(priv, ICSCR, 0);
	rcar_i2c_write(priv, ICSSR, 0);

	/* reset master mode */
	rcar_i2c_write(priv, ICMIER, 0);
	rcar_i2c_write(priv, ICMCR, 0);
	rcar_i2c_write(priv, ICMSR, 0);
	rcar_i2c_write(priv, ICMAR, 0);
	}

	static int rcar_i2c_bus_barrier(struct rcar_i2c_priv *priv)
	{
	int i;

	for (i = 0; i < LOOP_TIMEOUT; i++) {
	/* make sure that bus is not busy */
	if (!(rcar_i2c_read(priv, ICMCR) & FSDA))
	return 0;
	udelay(1);
	}

	return -EBUSY;
	}

	static int rcar_i2c_clock_calculate(struct rcar_i2c_priv *priv,
	u32 bus_speed,
	struct device *dev)
	{
	u32 scgd, cdf;
	u32 round, ick;
	u32 scl;
	u32 cdf_width;
	unsigned long rate;

	switch (priv->devtype) {
	case I2C_RCAR_GEN1:
	cdf_width = 2;
	break;
	case I2C_RCAR_GEN2:
	cdf_width = 3;
	break;
	default:
	dev_err(dev, "device type error\n");
	return -EIO;
	}

	/*
	* calculate SCL clock
	* see
	* ICCCR
	*
	* ick = clkp / (1 + CDF)
	* SCL = ick / (20 + SCGD * 8 + F[(ticf + tr + intd) * ick])
	*
	* ick : I2C internal clock < 20 MHz
	* ticf : I2C SCL falling time = 35 ns here
	* tr : I2C SCL rising time = 200 ns here
	* intd : LSI internal delay = 50 ns here
	* clkp : peripheral_clk
	* F[] : integer up-valuation
	*/
	rate = clk_get_rate(priv->clk);
	cdf = rate / 20000000;
	if (cdf >= 1 << cdf_width) {
	dev_err(dev, "Input clock %lu too high\n", rate);
	return -EIO;
	}
	ick = rate / (cdf + 1);

	/*
	* it is impossible to calculate large scale
	* number on u32. separate it
	*
	* F[(ticf + tr + intd) * ick]
	* = F[(35 + 200 + 50)ns * ick]
	* = F[285 * ick / 1000000000]
	* = F[(ick / 1000000) * 285 / 1000]
	*/
	round = (ick + 500000) / 1000000 * 285;
	round = (round + 500) / 1000;

	/*
	* SCL = ick / (20 + SCGD * 8 + F[(ticf + tr + intd) * ick])
	*
	* Calculation result (= SCL) should be less than
	* bus_speed for hardware safety
	*
	* We could use something along the lines of
	* div = ick / (bus_speed + 1) + 1;
	* scgd = (div - 20 - round + 7) / 8;
	* scl = ick / (20 + (scgd * 8) + round);
	* (not fully verified) but that would get pretty involved
	*/
	for (scgd = 0; scgd < 0x40; scgd++) {
	scl = ick / (20 + (scgd * 8) + round);
	if (scl <= bus_speed)
	goto scgd_find;
	}
	dev_err(dev, "it is impossible to calculate best SCL\n");
	return -EIO;

	scgd_find:
	dev_dbg(dev, "clk %d/%d(%lu), round %u, CDF:0x%x, SCGD: 0x%x\n",
	scl, bus_speed, clk_get_rate(priv->clk), round, cdf, scgd);

	/*
	* keep icccr value
	*/
	priv->icccr = scgd << cdf_width \| cdf;

	return 0;
	}

	static int rcar_i2c_prepare_msg(struct rcar_i2c_priv *priv)
	{
	int read = !!rcar_i2c_is_recv(priv);

	rcar_i2c_write(priv, ICMAR, (priv->msg->addr << 1) \| read);
	rcar_i2c_write(priv, ICMSR, 0);
	rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_START);
	rcar_i2c_write(priv, ICMIER, read ? RCAR_IRQ_RECV : RCAR_IRQ_SEND);

	return 0;
	}

	/*
	* interrupt functions
	*/
	static int rcar_i2c_irq_send(struct rcar_i2c_priv *priv, u32 msr)
	{
	struct i2c_msg *msg = priv->msg;

	/*
	* FIXME
	* sometimes, unknown interrupt happened.
	* Do nothing
	*/
	if (!(msr & MDE))
	return 0;

	/*
	* If address transfer phase finished,
	* goto data phase.
	*/
	if (msr & MAT)
	rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_DATA);

	if (priv->pos < msg->len) {
	/*
	* Prepare next data to ICRXTX register.
	* This data will go to _SHIFT_ register.
	*
	* *
	* [ICRXTX] -> [SHIFT] -> [I2C bus]
	*/
	rcar_i2c_write(priv, ICRXTX, msg->buf[priv->pos]);
	priv->pos++;

	} else {
	/*
	* The last data was pushed to ICRXTX on _PREV_ empty irq.
	* It is on _SHIFT_ register, and will sent to I2C bus.
	*
	* *
	* [ICRXTX] -> [SHIFT] -> [I2C bus]
	*/

	if (priv->flags & ID_LAST_MSG)
	/*
	* If current msg is the _LAST_ msg,
	* prepare stop condition here.
	* ID_DONE will be set on STOP irq.
	*/
	rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_STOP);
	else
	/*
	* If current msg is _NOT_ last msg,
	* it doesn't call stop phase.
	* thus, there is no STOP irq.
	* return ID_DONE here.
	*/
	return ID_DONE;
	}

	rcar_i2c_write(priv, ICMSR, RCAR_IRQ_ACK_SEND);

	return 0;
	}

	static int rcar_i2c_irq_recv(struct rcar_i2c_priv *priv, u32 msr)
	{
	struct i2c_msg *msg = priv->msg;

	/*
	* FIXME
	* sometimes, unknown interrupt happened.
	* Do nothing
	*/
	if (!(msr & MDR))
	return 0;

	if (msr & MAT) {
	/*
	* Address transfer phase finished,
	* but, there is no data at this point.
	* Do nothing.
	*/
	} else if (priv->pos < msg->len) {
	/*
	* get received data
	*/
	msg->buf[priv->pos] = rcar_i2c_read(priv, ICRXTX);
	priv->pos++;
	}

	/*
	* If next received data is the _LAST_,
	* go to STOP phase,
	* otherwise, go to DATA phase.
	*/
	if (priv->pos + 1 >= msg->len)
	rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_STOP);
	else
	rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_DATA);

	rcar_i2c_write(priv, ICMSR, RCAR_IRQ_ACK_RECV);

	return 0;
	}

	static irqreturn_t rcar_i2c_irq(int irq, void *ptr)
	{
	struct rcar_i2c_priv *priv = ptr;
	u32 msr;

	/-------------- spin lock -----------------/
	spin_lock(&priv->lock);

	msr = rcar_i2c_read(priv, ICMSR);

	/* Only handle interrupts that are currently enabled */
	msr &= rcar_i2c_read(priv, ICMIER);

	/* Arbitration lost */
	if (msr & MAL) {
	rcar_i2c_flags_set(priv, (ID_DONE \| ID_ARBLOST));
	goto out;
	}

	/* Nack */
	if (msr & MNR) {
	/* go to stop phase */
	rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_STOP);
	rcar_i2c_write(priv, ICMIER, RCAR_IRQ_STOP);
	rcar_i2c_flags_set(priv, ID_NACK);
	goto out;
	}

	/* Stop */
	if (msr & MST) {
	rcar_i2c_flags_set(priv, ID_DONE);
	goto out;
	}

	if (rcar_i2c_is_recv(priv))
	rcar_i2c_flags_set(priv, rcar_i2c_irq_recv(priv, msr));
	else
	rcar_i2c_flags_set(priv, rcar_i2c_irq_send(priv, msr));

	out:
	if (rcar_i2c_flags_has(priv, ID_DONE)) {
	rcar_i2c_write(priv, ICMIER, 0);
	rcar_i2c_write(priv, ICMSR, 0);
	wake_up(&priv->wait);
	}

	spin_unlock(&priv->lock);
	/-------------- spin unlock -----------------/

	return IRQ_HANDLED;
	}

	static int rcar_i2c_master_xfer(struct i2c_adapter *adap,
	struct i2c_msg *msgs,
	int num)
	{
	struct rcar_i2c_priv *priv = i2c_get_adapdata(adap);
	struct device *dev = rcar_i2c_priv_to_dev(priv);
	unsigned long flags;
	int i, ret, timeout;

	pm_runtime_get_sync(dev);

	/-------------- spin lock -----------------/
	spin_lock_irqsave(&priv->lock, flags);

	rcar_i2c_init(priv);
	/* start clock */
	rcar_i2c_write(priv, ICCCR, priv->icccr);

	spin_unlock_irqrestore(&priv->lock, flags);
	/-------------- spin unlock -----------------/

	ret = rcar_i2c_bus_barrier(priv);
	if (ret < 0)
	goto out;

	for (i = 0; i < num; i++) {
	/* This HW can't send STOP after address phase */
	if (msgs[i].len == 0) {
	ret = -EOPNOTSUPP;
	break;
	}

	/-------------- spin lock -----------------/
	spin_lock_irqsave(&priv->lock, flags);

	/* init each data */
	priv->msg = &msgs[i];
	priv->pos = 0;
	priv->flags = 0;
	if (priv->msg == &msgs[num - 1])
	rcar_i2c_flags_set(priv, ID_LAST_MSG);

	ret = rcar_i2c_prepare_msg(priv);

	spin_unlock_irqrestore(&priv->lock, flags);
	/-------------- spin unlock -----------------/

	if (ret < 0)
	break;

	timeout = wait_event_timeout(priv->wait,
	rcar_i2c_flags_has(priv, ID_DONE),
	5 * HZ);
	if (!timeout) {
	ret = -ETIMEDOUT;
	break;
	}

	if (rcar_i2c_flags_has(priv, ID_NACK)) {
	ret = -ENXIO;
	break;
	}

	if (rcar_i2c_flags_has(priv, ID_ARBLOST)) {
	ret = -EAGAIN;
	break;
	}

	if (rcar_i2c_flags_has(priv, ID_IOERROR)) {
	ret = -EIO;
	break;
	}

	ret = i + 1; /* The number of transfer */
	}
	out:
	pm_runtime_put(dev);

	if (ret < 0 && ret != -ENXIO)
	dev_err(dev, "error %d : %x\n", ret, priv->flags);

	return ret;
	}

	static u32 rcar_i2c_func(struct i2c_adapter *adap)
	{
	/* This HW can't do SMBUS_QUICK and NOSTART */
	return I2C_FUNC_I2C \| (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
	}

	static const struct i2c_algorithm rcar_i2c_algo = {
	.master_xfer = rcar_i2c_master_xfer,
	.functionality = rcar_i2c_func,
	};

	static const struct of_device_id rcar_i2c_dt_ids[] = {
	{ .compatible = "renesas,i2c-rcar", .data = (void *)I2C_RCAR_GEN1 },
	{ .compatible = "renesas,i2c-r8a7778", .data = (void *)I2C_RCAR_GEN1 },
	{ .compatible = "renesas,i2c-r8a7779", .data = (void *)I2C_RCAR_GEN1 },
	{ .compatible = "renesas,i2c-r8a7790", .data = (void *)I2C_RCAR_GEN2 },
	{ .compatible = "renesas,i2c-r8a7791", .data = (void *)I2C_RCAR_GEN2 },
	{ .compatible = "renesas,i2c-r8a7792", .data = (void *)I2C_RCAR_GEN2 },
	{ .compatible = "renesas,i2c-r8a7793", .data = (void *)I2C_RCAR_GEN2 },
	{ .compatible = "renesas,i2c-r8a7794", .data = (void *)I2C_RCAR_GEN2 },
	{},
	};
	MODULE_DEVICE_TABLE(of, rcar_i2c_dt_ids);

	static int rcar_i2c_probe(struct platform_device *pdev)
	{
	struct i2c_rcar_platform_data *pdata = dev_get_platdata(&pdev->dev);
	struct rcar_i2c_priv *priv;
	struct i2c_adapter *adap;
	struct resource *res;
	struct device *dev = &pdev->dev;
	u32 bus_speed;
	int irq, ret;

	priv = devm_kzalloc(dev, sizeof(struct rcar_i2c_priv), GFP_KERNEL);
	if (!priv)
	return -ENOMEM;

	priv->clk = devm_clk_get(dev, NULL);
	if (IS_ERR(priv->clk)) {
	dev_err(dev, "cannot get clock\n");
	return PTR_ERR(priv->clk);
	}

	bus_speed = 100000; /* default 100 kHz */
	ret = of_property_read_u32(dev->of_node, "clock-frequency", &bus_speed);
	if (ret < 0 && pdata && pdata->bus_speed)
	bus_speed = pdata->bus_speed;

	if (pdev->dev.of_node)
	priv->devtype = (long)of_match_device(rcar_i2c_dt_ids,
	dev)->data;
	else
	priv->devtype = platform_get_device_id(pdev)->driver_data;

	ret = rcar_i2c_clock_calculate(priv, bus_speed, dev);
	if (ret < 0)
	return ret;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	priv->io = devm_ioremap_resource(dev, res);
	if (IS_ERR(priv->io))
	return PTR_ERR(priv->io);

	irq = platform_get_irq(pdev, 0);
	init_waitqueue_head(&priv->wait);
	spin_lock_init(&priv->lock);

	adap = &priv->adap;
	adap->nr = pdev->id;
	adap->algo = &rcar_i2c_algo;
	adap->class = I2C_CLASS_DEPRECATED;
	adap->retries = 3;
	adap->dev.parent = dev;
	adap->dev.of_node = dev->of_node;
	i2c_set_adapdata(adap, priv);
	strlcpy(adap->name, pdev->name, sizeof(adap->name));

	ret = devm_request_irq(dev, irq, rcar_i2c_irq, 0,
	dev_name(dev), priv);
	if (ret < 0) {
	dev_err(dev, "cannot get irq %d\n", irq);
	return ret;
	}

	ret = i2c_add_numbered_adapter(adap);
	if (ret < 0) {
	dev_err(dev, "reg adap failed: %d\n", ret);
	return ret;
	}

	pm_runtime_enable(dev);
	platform_set_drvdata(pdev, priv);

	dev_info(dev, "probed\n");

	return 0;
	}

	static int rcar_i2c_remove(struct platform_device *pdev)
	{
	struct rcar_i2c_priv *priv = platform_get_drvdata(pdev);
	struct device *dev = &pdev->dev;

	i2c_del_adapter(&priv->adap);
	pm_runtime_disable(dev);

	return 0;
	}

	static struct platform_device_id rcar_i2c_id_table[] = {
	{ "i2c-rcar", I2C_RCAR_GEN1 },
	{ "i2c-rcar_gen1", I2C_RCAR_GEN1 },
	{ "i2c-rcar_gen2", I2C_RCAR_GEN2 },
	{},
	};
	MODULE_DEVICE_TABLE(platform, rcar_i2c_id_table);

	static struct platform_driver rcar_i2c_driver = {
	.driver = {
	.name = "i2c-rcar",
	.owner = THIS_MODULE,
	.of_match_table = rcar_i2c_dt_ids,
	},
	.probe = rcar_i2c_probe,
	.remove = rcar_i2c_remove,
	.id_table = rcar_i2c_id_table,
	};

	module_platform_driver(rcar_i2c_driver);

	MODULE_LICENSE("GPL v2");
	MODULE_DESCRIPTION("Renesas R-Car I2C bus driver");
	MODULE_AUTHOR("Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>");