i2c: add Renesas R-Car I2C driver

R-Car I2C is similar with SH7760 I2C.
But the SH7760 I2C driver had many workaround operations, since H/W had bugs.
Thus, it was pointless to keep compatible between SH7760 and R-Car I2C drivers.
This patch creates new Renesas R-Car I2C driver.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>

1 files changed, 709 insertions, 0 deletions

diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
new file mode 100644
index 0000000..f9399d1
--- /dev/null
+++ b/drivers/i2c/busses/i2c-rcar.c
@@ -0,0 +1,709 @@
+/*
+ *  drivers/i2c/busses/i2c-rcar.c
+ *
+ * Copyright (C) 2012 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; 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/clk.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/init.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/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 */
+#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 */
+
+/* ICMIE */
+#define MNRE	(1 << 6)	/* nack irq en */
+#define MALE	(1 << 5)	/* arblos irq en */
+#define MSTE	(1 << 4)	/* stop irq en */
+#define MDEE	(1 << 3)
+#define MDTE	(1 << 2)
+#define MDRE	(1 << 1)
+#define MATE	(1 << 0)	/* address sent irq en */
+
+
+enum {
+	RCAR_BUS_PHASE_ADDR,
+	RCAR_BUS_PHASE_DATA,
+	RCAR_BUS_PHASE_STOP,
+};
+
+enum {
+	RCAR_IRQ_CLOSE,
+	RCAR_IRQ_OPEN_FOR_SEND,
+	RCAR_IRQ_OPEN_FOR_RECV,
+	RCAR_IRQ_OPEN_FOR_STOP,
+};
+
+/*
+ * flags
+ */
+#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)
+
+struct rcar_i2c_priv {
+	void __iomem *io;
+	struct i2c_adapter adap;
+	struct i2c_msg	*msg;
+
+	spinlock_t lock;
+	wait_queue_head_t wait;
+
+	int pos;
+	int irq;
+	u32 icccr;
+	u32 flags;
+};
+
+#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
+
+/*
+ *		basic functions
+ */
+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 void rcar_i2c_irq_mask(struct rcar_i2c_priv *priv, int open)
+{
+	u32 val = MNRE | MALE | MSTE | MATE; /* default */
+
+	switch (open) {
+	case RCAR_IRQ_OPEN_FOR_SEND:
+		val |= MDEE; /* default + send */
+		break;
+	case RCAR_IRQ_OPEN_FOR_RECV:
+		val |= MDRE; /* default + read */
+		break;
+	case RCAR_IRQ_OPEN_FOR_STOP:
+		val = MSTE; /* stop irq only */
+		break;
+	case RCAR_IRQ_CLOSE:
+	default:
+		val = 0; /* all close */
+		break;
+	}
+	rcar_i2c_write(priv, ICMIER, val);
+}
+
+static void rcar_i2c_set_addr(struct rcar_i2c_priv *priv, u32 recv)
+{
+	rcar_i2c_write(priv, ICMAR, (priv->msg->addr << 1) | recv);
+}
+
+/*
+ *		bus control functions
+ */
+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 void rcar_i2c_bus_phase(struct rcar_i2c_priv *priv, int phase)
+{
+	switch (phase) {
+	case RCAR_BUS_PHASE_ADDR:
+		rcar_i2c_write(priv, ICMCR, MDBS | MIE | ESG);
+		break;
+	case RCAR_BUS_PHASE_DATA:
+		rcar_i2c_write(priv, ICMCR, MDBS | MIE);
+		break;
+	case RCAR_BUS_PHASE_STOP:
+		rcar_i2c_write(priv, ICMCR, MDBS | MIE | FSB);
+		break;
+	}
+}
+
+/*
+ *		clock function
+ */
+static int rcar_i2c_clock_calculate(struct rcar_i2c_priv *priv,
+				    u32 bus_speed,
+				    struct device *dev)
+{
+	struct clk *clkp = clk_get(NULL, "peripheral_clk");
+	u32 scgd, cdf;
+	u32 round, ick;
+	u32 scl;
+
+	if (!clkp) {
+		dev_err(dev, "there is no peripheral_clk\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
+	 */
+	for (cdf = 0; cdf < 4; cdf++) {
+		ick = clk_get_rate(clkp) / (1 + cdf);
+		if (ick < 20000000)
+			goto ick_find;
+	}
+	dev_err(dev, "there is no best CDF\n");
+	return -EIO;
+
+ick_find:
+	/*
+	 * 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
+	 */
+	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(clkp), round, cdf, scgd);
+
+	/*
+	 * keep icccr value
+	 */
+	priv->icccr = (scgd << 2 | cdf);
+
+	return 0;
+}
+
+static void rcar_i2c_clock_start(struct rcar_i2c_priv *priv)
+{
+	rcar_i2c_write(priv, ICCCR, priv->icccr);
+}
+
+/*
+ *		status functions
+ */
+static u32 rcar_i2c_status_get(struct rcar_i2c_priv *priv)
+{
+	return rcar_i2c_read(priv, ICMSR);
+}
+
+#define rcar_i2c_status_clear(priv) rcar_i2c_status_bit_clear(priv, 0xffffffff)
+static void rcar_i2c_status_bit_clear(struct rcar_i2c_priv *priv, u32 bit)
+{
+	rcar_i2c_write(priv, ICMSR, ~bit);
+}
+
+/*
+ *		recv/send functions
+ */
+static int rcar_i2c_recv(struct rcar_i2c_priv *priv)
+{
+	rcar_i2c_set_addr(priv, 1);
+	rcar_i2c_status_clear(priv);
+	rcar_i2c_bus_phase(priv, RCAR_BUS_PHASE_ADDR);
+	rcar_i2c_irq_mask(priv, RCAR_IRQ_OPEN_FOR_RECV);
+
+	return 0;
+}
+
+static int rcar_i2c_send(struct rcar_i2c_priv *priv)
+{
+	int ret;
+
+	/*
+	 * It should check bus status when send case
+	 */
+	ret = rcar_i2c_bus_barrier(priv);
+	if (ret < 0)
+		return ret;
+
+	rcar_i2c_set_addr(priv, 0);
+	rcar_i2c_status_clear(priv);
+	rcar_i2c_bus_phase(priv, RCAR_BUS_PHASE_ADDR);
+	rcar_i2c_irq_mask(priv, RCAR_IRQ_OPEN_FOR_SEND);
+
+	return 0;
+}
+
+#define rcar_i2c_send_restart(priv) rcar_i2c_status_bit_clear(priv, (MAT | MDE))
+#define rcar_i2c_recv_restart(priv) rcar_i2c_status_bit_clear(priv, (MAT | MDR))
+
+/*
+ *		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_bus_phase(priv, 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_bus_phase(priv, 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_send_restart(priv);
+
+	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_bus_phase(priv, RCAR_BUS_PHASE_STOP);
+	else
+		rcar_i2c_bus_phase(priv, RCAR_BUS_PHASE_DATA);
+
+	rcar_i2c_recv_restart(priv);
+
+	return 0;
+}
+
+static irqreturn_t rcar_i2c_irq(int irq, void *ptr)
+{
+	struct rcar_i2c_priv *priv = ptr;
+	struct device *dev = rcar_i2c_priv_to_dev(priv);
+	u32 msr;
+
+	/*-------------- spin lock -----------------*/
+	spin_lock(&priv->lock);
+
+	msr = rcar_i2c_status_get(priv);
+
+	/*
+	 * Arbitration lost
+	 */
+	if (msr & MAL) {
+		/*
+		 * CAUTION
+		 *
+		 * When arbitration lost, device become _slave_ mode.
+		 */
+		dev_dbg(dev, "Arbitration Lost\n");
+		rcar_i2c_flags_set(priv, (ID_DONE | ID_ARBLOST));
+		goto out;
+	}
+
+	/*
+	 * Stop
+	 */
+	if (msr & MST) {
+		dev_dbg(dev, "Stop\n");
+		rcar_i2c_flags_set(priv, ID_DONE);
+		goto out;
+	}
+
+	/*
+	 * Nack
+	 */
+	if (msr & MNR) {
+		dev_dbg(dev, "Nack\n");
+
+		/* go to stop phase */
+		rcar_i2c_bus_phase(priv, RCAR_BUS_PHASE_STOP);
+		rcar_i2c_irq_mask(priv, RCAR_IRQ_OPEN_FOR_STOP);
+		rcar_i2c_flags_set(priv, ID_NACK);
+		goto out;
+	}
+
+	/*
+	 * recv/send
+	 */
+	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_irq_mask(priv, RCAR_IRQ_CLOSE);
+		rcar_i2c_status_clear(priv);
+		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);
+	rcar_i2c_clock_start(priv);
+
+	spin_unlock_irqrestore(&priv->lock, flags);
+	/*-------------- spin unlock -----------------*/
+
+	ret = -EINVAL;
+	for (i = 0; i < num; i++) {
+		/*-------------- 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);
+
+		/* start send/recv */
+		if (rcar_i2c_is_recv(priv))
+			ret = rcar_i2c_recv(priv);
+		else
+			ret = rcar_i2c_send(priv);
+
+		spin_unlock_irqrestore(&priv->lock, flags);
+		/*-------------- spin unlock -----------------*/
+
+		if (ret < 0)
+			break;
+
+		/*
+		 * wait result
+		 */
+		timeout = wait_event_timeout(priv->wait,
+					     rcar_i2c_flags_has(priv, ID_DONE),
+					     5 * HZ);
+		if (!timeout) {
+			ret = -ETIMEDOUT;
+			break;
+		}
+
+		/*
+		 * error handling
+		 */
+		if (rcar_i2c_flags_has(priv, ID_NACK)) {
+			ret = -EREMOTEIO;
+			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 */
+	}
+
+	pm_runtime_put(dev);
+
+	if (ret < 0)
+		dev_err(dev, "error %d : %x\n", ret, priv->flags);
+
+	return ret;
+}
+
+static u32 rcar_i2c_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm rcar_i2c_algo = {
+	.master_xfer	= rcar_i2c_master_xfer,
+	.functionality	= rcar_i2c_func,
+};
+
+static int __devinit rcar_i2c_probe(struct platform_device *pdev)
+{
+	struct i2c_rcar_platform_data *pdata = pdev->dev.platform_data;
+	struct rcar_i2c_priv *priv;
+	struct i2c_adapter *adap;
+	struct resource *res;
+	struct device *dev = &pdev->dev;
+	u32 bus_speed;
+	int ret;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(dev, "no mmio resources\n");
+		return -ENODEV;
+	}
+
+	priv = devm_kzalloc(dev, sizeof(struct rcar_i2c_priv), GFP_KERNEL);
+	if (!priv) {
+		dev_err(dev, "no mem for private data\n");
+		return -ENOMEM;
+	}
+
+	bus_speed = 100000; /* default 100 kHz */
+	if (pdata && pdata->bus_speed)
+		bus_speed = pdata->bus_speed;
+	ret = rcar_i2c_clock_calculate(priv, bus_speed, dev);
+	if (ret < 0)
+		return ret;
+
+	priv->io = devm_ioremap(dev, res->start, resource_size(res));
+	if (!priv->io) {
+		dev_err(dev, "cannot ioremap\n");
+		return -ENODEV;
+	}
+
+	priv->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_HWMON | I2C_CLASS_SPD;
+	adap->retries		= 3;
+	adap->dev.parent	= dev;
+	i2c_set_adapdata(adap, priv);
+	strlcpy(adap->name, pdev->name, sizeof(adap->name));
+
+	ret = devm_request_irq(dev, priv->irq, rcar_i2c_irq, 0,
+			       dev_name(dev), priv);
+	if (ret < 0) {
+		dev_err(dev, "cannot get irq %d\n", priv->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 __devexit 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_driver rcar_i2c_drv = {
+	.driver	= {
+		.name	= "i2c-rcar",
+		.owner	= THIS_MODULE,
+	},
+	.probe		= rcar_i2c_probe,
+	.remove		= __devexit_p(rcar_i2c_remove),
+};
+
+module_platform_driver(rcar_i2c_drv);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Renesas R-Car I2C bus driver");
+MODULE_AUTHOR("Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>");