drivers/i2c/busses/i2c-sh7760.c - kernel/prism - Git at Google

 /*
  * I2C bus driver for the SH7760 I2C Interfaces.
  *
  * (c) 2005-2008 MSC Vertriebsges.m.b.H, Manuel Lauss <mlau@msc-ge.com>
  *
  * licensed under the terms outlined in the file COPYING.
  *
  */

 #include <linux/completion.h>
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/i2c.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/ioport.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>

 #include <asm/clock.h>
 #include <asm/i2c-sh7760.h>
 #include <asm/io.h>

 /* register offsets */
 #define I2CSCR		0x0		/* slave ctrl		*/
 #define I2CMCR		0x4		/* master ctrl		*/
 #define I2CSSR		0x8		/* slave status		*/
 #define I2CMSR		0xC		/* master status	*/
 #define I2CSIER		0x10		/* slave irq enable	*/
 #define I2CMIER		0x14		/* master irq enable	*/
 #define I2CCCR		0x18		/* clock dividers	*/
 #define I2CSAR		0x1c		/* slave address	*/
 #define I2CMAR		0x20		/* master address	*/
 #define I2CRXTX		0x24		/* data port		*/
 #define I2CFCR		0x28		/* fifo control		*/
 #define I2CFSR		0x2C		/* fifo status		*/
 #define I2CFIER		0x30		/* fifo irq enable	*/
 #define I2CRFDR		0x34		/* rx fifo count	*/
 #define I2CTFDR		0x38		/* tx fifo count	*/

 #define REGSIZE		0x3C

 #define MCR_MDBS	0x80		/* non-fifo mode switch	*/
 #define MCR_FSCL	0x40		/* override SCL pin	*/
 #define MCR_FSDA	0x20		/* override SDA pin	*/
 #define MCR_OBPC	0x10		/* override pins	*/
 #define MCR_MIE		0x08		/* master if enable	*/
 #define MCR_TSBE	0x04
 #define MCR_FSB		0x02		/* force stop bit	*/
 #define MCR_ESG		0x01		/* en startbit gen.	*/

 #define MSR_MNR		0x40		/* nack received	*/
 #define MSR_MAL		0x20		/* arbitration lost	*/
 #define MSR_MST		0x10		/* sent a stop		*/
 #define MSR_MDE		0x08
 #define MSR_MDT		0x04
 #define MSR_MDR		0x02
 #define MSR_MAT		0x01		/* slave addr xfer done	*/

 #define MIE_MNRE	0x40		/* nack irq en		*/
 #define MIE_MALE	0x20		/* arblos irq en	*/
 #define MIE_MSTE	0x10		/* stop irq en		*/
 #define MIE_MDEE	0x08
 #define MIE_MDTE	0x04
 #define MIE_MDRE	0x02
 #define MIE_MATE	0x01		/* address sent irq en	*/

 #define FCR_RFRST	0x02		/* reset rx fifo	*/
 #define FCR_TFRST	0x01		/* reset tx fifo	*/

 #define FSR_TEND	0x04		/* last byte sent	*/
 #define FSR_RDF		0x02		/* rx fifo trigger	*/
 #define FSR_TDFE	0x01		/* tx fifo empty	*/

 #define FIER_TEIE	0x04		/* tx fifo empty irq en	*/
 #define FIER_RXIE	0x02		/* rx fifo trig irq en	*/
 #define FIER_TXIE	0x01		/* tx fifo trig irq en	*/

 #define FIFO_SIZE	16

 struct cami2c {
 	void __iomem *iobase;
 	struct i2c_adapter adap;

 	/* message processing */
 	struct i2c_msg	*msg;
 #define IDF_SEND	1
 #define IDF_RECV	2
 #define IDF_STOP	4
 	int		flags;

 #define IDS_DONE	1
 #define IDS_ARBLOST	2
 #define IDS_NACK	4
 	int		status;
 	struct completion xfer_done;

 	int irq;
 	struct resource *ioarea;
 };

 static inline void OUT32(struct cami2c *cam, int reg, unsigned long val)
 {
 	ctrl_outl(val, (unsigned long)cam->iobase + reg);
 }

 static inline unsigned long IN32(struct cami2c *cam, int reg)
 {
 	return ctrl_inl((unsigned long)cam->iobase + reg);
 }

 static irqreturn_t sh7760_i2c_irq(int irq, void *ptr)
 {
 	struct cami2c *id = ptr;
 	struct i2c_msg *msg = id->msg;
 	char *data = msg->buf;
 	unsigned long msr, fsr, fier, len;

 	msr = IN32(id, I2CMSR);
 	fsr = IN32(id, I2CFSR);

 	/* arbitration lost */
 	if (msr & MSR_MAL) {
 		OUT32(id, I2CMCR, 0);
 		OUT32(id, I2CSCR, 0);
 		OUT32(id, I2CSAR, 0);
 		id->status |= IDS_DONE | IDS_ARBLOST;
 		goto out;
 	}

 	if (msr & MSR_MNR) {
 		/* NACK handling is very screwed up.  After receiving a
 		 * NAK IRQ one has to wait a bit  before writing to any
 		 * registers, or the ctl will lock up. After that delay
 		 * do a normal i2c stop. Then wait at least 1 ms before
 		 * attempting another transfer or ctl will stop working
 		 */
 		udelay(100);	/* wait or risk ctl hang */
 		OUT32(id, I2CFCR, FCR_RFRST | FCR_TFRST);
 		OUT32(id, I2CMCR, MCR_MIE | MCR_FSB);
 		OUT32(id, I2CFIER, 0);
 		OUT32(id, I2CMIER, MIE_MSTE);
 		OUT32(id, I2CSCR, 0);
 		OUT32(id, I2CSAR, 0);
 		id->status |= IDS_NACK;
 		msr &= ~MSR_MAT;
 		fsr = 0;
 		/* In some cases the MST bit is also set. */
 	}

 	/* i2c-stop was sent */
 	if (msr & MSR_MST) {
 		id->status |= IDS_DONE;
 		goto out;
 	}

 	/* i2c slave addr was sent; set to "normal" operation */
 	if (msr & MSR_MAT)
 		OUT32(id, I2CMCR, MCR_MIE);

 	fier = IN32(id, I2CFIER);

 	if (fsr & FSR_RDF) {
 		len = IN32(id, I2CRFDR);
 		if (msg->len <= len) {
 			if (id->flags & IDF_STOP) {
 				OUT32(id, I2CMCR, MCR_MIE | MCR_FSB);
 				OUT32(id, I2CFIER, 0);
 				/* manual says: wait >= 0.5 SCL times */
 				udelay(5);
 				/* next int should be MST */
 			} else {
 				id->status |= IDS_DONE;
 				/* keep the RDF bit: ctrl holds SCL low
 				 * until the setup for the next i2c_msg
 				 * clears this bit.
 				 */
 				fsr &= ~FSR_RDF;
 			}
 		}
 		while (msg->len && len) {
 			*data++ = IN32(id, I2CRXTX);
 			msg->len--;
 			len--;
 		}

 		if (msg->len) {
 			len = (msg->len >= FIFO_SIZE) ? FIFO_SIZE - 1
 						      : msg->len - 1;

 			OUT32(id, I2CFCR, FCR_TFRST | ((len & 0xf) << 4));
 		}

 	} else if (id->flags & IDF_SEND) {
 		if ((fsr & FSR_TEND) && (msg->len < 1)) {
 			if (id->flags & IDF_STOP) {
 				OUT32(id, I2CMCR, MCR_MIE | MCR_FSB);
 			} else {
 				id->status |= IDS_DONE;
 				/* keep the TEND bit: ctl holds SCL low
 				 * until the setup for the next i2c_msg
 				 * clears this bit.
 				 */
 				fsr &= ~FSR_TEND;
 			}
 		}
 		if (fsr & FSR_TDFE) {
 			while (msg->len && (IN32(id, I2CTFDR) < FIFO_SIZE)) {
 				OUT32(id, I2CRXTX, *data++);
 				msg->len--;
 			}

 			if (msg->len < 1) {
 				fier &= ~FIER_TXIE;
 				OUT32(id, I2CFIER, fier);
 			} else {
 				len = (msg->len >= FIFO_SIZE) ? 2 : 0;
 				OUT32(id, I2CFCR,
 					  FCR_RFRST | ((len & 3) << 2));
 			}
 		}
 	}
 out:
 	if (id->status & IDS_DONE) {
 		OUT32(id, I2CMIER, 0);
 		OUT32(id, I2CFIER, 0);
 		id->msg = NULL;
 		complete(&id->xfer_done);
 	}
 	/* clear status flags and ctrl resumes work */
 	OUT32(id, I2CMSR, ~msr);
 	OUT32(id, I2CFSR, ~fsr);
 	OUT32(id, I2CSSR, 0);

 	return IRQ_HANDLED;
 }


 /* prepare and start a master receive operation */
 static void sh7760_i2c_mrecv(struct cami2c *id)
 {
 	int len;

 	id->flags |= IDF_RECV;

 	/* set the slave addr reg; otherwise rcv wont work! */
 	OUT32(id, I2CSAR, 0xfe);
 	OUT32(id, I2CMAR, (id->msg->addr << 1) | 1);

 	/* adjust rx fifo trigger */
 	if (id->msg->len >= FIFO_SIZE)
 		len = FIFO_SIZE - 1;	/* trigger at fifo full */
 	else
 		len = id->msg->len - 1;	/* trigger before all received */

 	OUT32(id, I2CFCR, FCR_RFRST | FCR_TFRST);
 	OUT32(id, I2CFCR, FCR_TFRST | ((len & 0xF) << 4));

 	OUT32(id, I2CMSR, 0);
 	OUT32(id, I2CMCR, MCR_MIE | MCR_ESG);
 	OUT32(id, I2CMIER, MIE_MNRE | MIE_MALE | MIE_MSTE | MIE_MATE);
 	OUT32(id, I2CFIER, FIER_RXIE);
 }

 /* prepare and start a master send operation */
 static void sh7760_i2c_msend(struct cami2c *id)
 {
 	int len;

 	id->flags |= IDF_SEND;

 	/* set the slave addr reg; otherwise xmit wont work! */
 	OUT32(id, I2CSAR, 0xfe);
 	OUT32(id, I2CMAR, (id->msg->addr << 1) | 0);

 	/* adjust tx fifo trigger */
 	if (id->msg->len >= FIFO_SIZE)
 		len = 2;	/* trig: 2 bytes left in TX fifo */
 	else
 		len = 0;	/* trig: 8 bytes left in TX fifo */

 	OUT32(id, I2CFCR, FCR_RFRST | FCR_TFRST);
 	OUT32(id, I2CFCR, FCR_RFRST | ((len & 3) << 2));

 	while (id->msg->len && IN32(id, I2CTFDR) < FIFO_SIZE) {
 		OUT32(id, I2CRXTX, *(id->msg->buf));
 		(id->msg->len)--;
 		(id->msg->buf)++;
 	}

 	OUT32(id, I2CMSR, 0);
 	OUT32(id, I2CMCR, MCR_MIE | MCR_ESG);
 	OUT32(id, I2CFSR, 0);
 	OUT32(id, I2CMIER, MIE_MNRE | MIE_MALE | MIE_MSTE | MIE_MATE);
 	OUT32(id, I2CFIER, FIER_TEIE | (id->msg->len ? FIER_TXIE : 0));
 }

 static inline int sh7760_i2c_busy_check(struct cami2c *id)
 {
 	return (IN32(id, I2CMCR) & MCR_FSDA);
 }

 static int sh7760_i2c_master_xfer(struct i2c_adapter *adap,
 				  struct i2c_msg *msgs,
 				  int num)
 {
 	struct cami2c *id = adap->algo_data;
 	int i, retr;

 	if (sh7760_i2c_busy_check(id)) {
 		dev_err(&adap->dev, "sh7760-i2c%d: bus busy!\n", adap->nr);
 		return -EBUSY;
 	}

 	i = 0;
 	while (i < num) {
 		retr = adap->retries;
 retry:
 		id->flags = ((i == (num-1)) ? IDF_STOP : 0);
 		id->status = 0;
 		id->msg = msgs;
 		init_completion(&id->xfer_done);

 		if (msgs->flags & I2C_M_RD)
 			sh7760_i2c_mrecv(id);
 		else
 			sh7760_i2c_msend(id);

 		wait_for_completion(&id->xfer_done);

 		if (id->status == 0) {
 			num = -EIO;
 			break;
 		}

 		if (id->status & IDS_NACK) {
 			/* wait a bit or i2c module stops working */
 			mdelay(1);
 			num = -EREMOTEIO;
 			break;
 		}

 		if (id->status & IDS_ARBLOST) {
 			if (retr--) {
 				mdelay(2);
 				goto retry;
 			}
 			num = -EREMOTEIO;
 			break;
 		}

 		msgs++;
 		i++;
 	}

 	id->msg = NULL;
 	id->flags = 0;
 	id->status = 0;

 	OUT32(id, I2CMCR, 0);
 	OUT32(id, I2CMSR, 0);
 	OUT32(id, I2CMIER, 0);
 	OUT32(id, I2CFIER, 0);

 	/* reset slave module registers too: master mode enables slave
 	 * module for receive ops (ack, data). Without this reset,
 	 * eternal bus activity might be reported after NACK / ARBLOST.
 	 */
 	OUT32(id, I2CSCR, 0);
 	OUT32(id, I2CSAR, 0);
 	OUT32(id, I2CSSR, 0);

 	return num;
 }

 static u32 sh7760_i2c_func(struct i2c_adapter *adap)
 {
 	return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
 }

 static const struct i2c_algorithm sh7760_i2c_algo = {
 	.master_xfer	= sh7760_i2c_master_xfer,
 	.functionality	= sh7760_i2c_func,
 };

 /* calculate CCR register setting for a desired scl clock.  SCL clock is
  * derived from I2C module clock  (iclk)  which in turn is derived from
  * peripheral module clock (mclk, usually around 33MHz):
  * iclk = mclk/(CDF + 1).  iclk must be < 20MHz.
  * scl = iclk/(SCGD*8 + 20).
  */
 static int __devinit calc_CCR(unsigned long scl_hz)
 {
 	struct clk *mclk;
 	unsigned long mck, m1, dff, odff, iclk;
 	signed char cdf, cdfm;
 	int scgd, scgdm, scgds;

 	mclk = clk_get(NULL, "peripheral_clk");
 	if (IS_ERR(mclk)) {
 		return PTR_ERR(mclk);
 	} else {
 		mck = mclk->rate;
 		clk_put(mclk);
 	}

 	odff = scl_hz;
 	scgdm = cdfm = m1 = 0;
 	for (cdf = 3; cdf >= 0; cdf--) {
 		iclk = mck / (1 + cdf);
 		if (iclk >= 20000000)
 			continue;
 		scgds = ((iclk / scl_hz) - 20) >> 3;
 		for (scgd = scgds; (scgd < 63) && scgd <= scgds + 1; scgd++) {
 			m1 = iclk / (20 + (scgd << 3));
 			dff = abs(scl_hz - m1);
 			if (dff < odff) {
 				odff = dff;
 				cdfm = cdf;
 				scgdm = scgd;
 			}
 		}
 	}
 	/* fail if more than 25% off of requested SCL */
 	if (odff > (scl_hz >> 2))
 		return -EINVAL;

 	/* create a CCR register value */
 	return ((scgdm << 2) | cdfm);
 }

 static int __devinit sh7760_i2c_probe(struct platform_device *pdev)
 {
 	struct sh7760_i2c_platdata *pd;
 	struct resource *res;
 	struct cami2c *id;
 	int ret;

 	pd = pdev->dev.platform_data;
 	if (!pd) {
 		dev_err(&pdev->dev, "no platform_data!\n");
 		ret = -ENODEV;
 		goto out0;
 	}

 	id = kzalloc(sizeof(struct cami2c), GFP_KERNEL);
 	if (!id) {
 		dev_err(&pdev->dev, "no mem for private data\n");
 		ret = -ENOMEM;
 		goto out0;
 	}

 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!res) {
 		dev_err(&pdev->dev, "no mmio resources\n");
 		ret = -ENODEV;
 		goto out1;
 	}

 	id->ioarea = request_mem_region(res->start, REGSIZE, pdev->name);
 	if (!id->ioarea) {
 		dev_err(&pdev->dev, "mmio already reserved\n");
 		ret = -EBUSY;
 		goto out1;
 	}

 	id->iobase = ioremap(res->start, REGSIZE);
 	if (!id->iobase) {
 		dev_err(&pdev->dev, "cannot ioremap\n");
 		ret = -ENODEV;
 		goto out2;
 	}

 	id->irq = platform_get_irq(pdev, 0);

 	id->adap.nr = pdev->id;
 	id->adap.algo = &sh7760_i2c_algo;
 	id->adap.class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
 	id->adap.retries = 3;
 	id->adap.algo_data = id;
 	id->adap.dev.parent = &pdev->dev;
 	snprintf(id->adap.name, sizeof(id->adap.name),
 		"SH7760 I2C at %08lx", (unsigned long)res->start);

 	OUT32(id, I2CMCR, 0);
 	OUT32(id, I2CMSR, 0);
 	OUT32(id, I2CMIER, 0);
 	OUT32(id, I2CMAR, 0);
 	OUT32(id, I2CSIER, 0);
 	OUT32(id, I2CSAR, 0);
 	OUT32(id, I2CSCR, 0);
 	OUT32(id, I2CSSR, 0);
 	OUT32(id, I2CFIER, 0);
 	OUT32(id, I2CFCR, FCR_RFRST | FCR_TFRST);
 	OUT32(id, I2CFSR, 0);

 	ret = calc_CCR(pd->speed_khz * 1000);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "invalid SCL clock: %dkHz\n",
 			pd->speed_khz);
 		goto out3;
 	}
 	OUT32(id, I2CCCR, ret);

 	if (request_irq(id->irq, sh7760_i2c_irq, IRQF_DISABLED,
 			SH7760_I2C_DEVNAME, id)) {
 		dev_err(&pdev->dev, "cannot get irq %d\n", id->irq);
 		ret = -EBUSY;
 		goto out3;
 	}

 	ret = i2c_add_numbered_adapter(&id->adap);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "reg adap failed: %d\n", ret);
 		goto out4;
 	}

 	platform_set_drvdata(pdev, id);

 	dev_info(&pdev->dev, "%d kHz mmio %08x irq %d\n",
 		 pd->speed_khz, res->start, id->irq);

 	return 0;

 out4:
 	free_irq(id->irq, id);
 out3:
 	iounmap(id->iobase);
 out2:
 	release_resource(id->ioarea);
 	kfree(id->ioarea);
 out1:
 	kfree(id);
 out0:
 	return ret;
 }

 static int __devexit sh7760_i2c_remove(struct platform_device *pdev)
 {
 	struct cami2c *id = platform_get_drvdata(pdev);

 	i2c_del_adapter(&id->adap);
 	free_irq(id->irq, id);
 	iounmap(id->iobase);
 	release_resource(id->ioarea);
 	kfree(id->ioarea);
 	kfree(id);
 	platform_set_drvdata(pdev, NULL);

 	return 0;
 }

 static struct platform_driver sh7760_i2c_drv = {
 	.driver	= {
 		.name	= SH7760_I2C_DEVNAME,
 		.owner	= THIS_MODULE,
 	},
 	.probe		= sh7760_i2c_probe,
 	.remove		= __devexit_p(sh7760_i2c_remove),
 };

 static int __init sh7760_i2c_init(void)
 {
 	return platform_driver_register(&sh7760_i2c_drv);
 }

 static void __exit sh7760_i2c_exit(void)
 {
 	platform_driver_unregister(&sh7760_i2c_drv);
 }

 module_init(sh7760_i2c_init);
 module_exit(sh7760_i2c_exit);

 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("SH7760 I2C bus driver");
 MODULE_AUTHOR("Manuel Lauss <mano@roarinelk.homelinux.net>");
	/*
	* I2C bus driver for the SH7760 I2C Interfaces.
	*
	* (c) 2005-2008 MSC Vertriebsges.m.b.H, Manuel Lauss <mlau@msc-ge.com>
	*
	* licensed under the terms outlined in the file COPYING.
	*
	*/

	#include <linux/completion.h>
	#include <linux/delay.h>
	#include <linux/err.h>
	#include <linux/i2c.h>
	#include <linux/init.h>
	#include <linux/interrupt.h>
	#include <linux/ioport.h>
	#include <linux/platform_device.h>
	#include <linux/slab.h>

	#include <asm/clock.h>
	#include <asm/i2c-sh7760.h>
	#include <asm/io.h>

	/* register offsets */
	#define I2CSCR 0x0 /* slave ctrl */
	#define I2CMCR 0x4 /* master ctrl */
	#define I2CSSR 0x8 /* slave status */
	#define I2CMSR 0xC /* master status */
	#define I2CSIER 0x10 /* slave irq enable */
	#define I2CMIER 0x14 /* master irq enable */
	#define I2CCCR 0x18 /* clock dividers */
	#define I2CSAR 0x1c /* slave address */
	#define I2CMAR 0x20 /* master address */
	#define I2CRXTX 0x24 /* data port */
	#define I2CFCR 0x28 /* fifo control */
	#define I2CFSR 0x2C /* fifo status */
	#define I2CFIER 0x30 /* fifo irq enable */
	#define I2CRFDR 0x34 /* rx fifo count */
	#define I2CTFDR 0x38 /* tx fifo count */

	#define REGSIZE 0x3C

	#define MCR_MDBS 0x80 /* non-fifo mode switch */
	#define MCR_FSCL 0x40 /* override SCL pin */
	#define MCR_FSDA 0x20 /* override SDA pin */
	#define MCR_OBPC 0x10 /* override pins */
	#define MCR_MIE 0x08 /* master if enable */
	#define MCR_TSBE 0x04
	#define MCR_FSB 0x02 /* force stop bit */
	#define MCR_ESG 0x01 /* en startbit gen. */

	#define MSR_MNR 0x40 /* nack received */
	#define MSR_MAL 0x20 /* arbitration lost */
	#define MSR_MST 0x10 /* sent a stop */
	#define MSR_MDE 0x08
	#define MSR_MDT 0x04
	#define MSR_MDR 0x02
	#define MSR_MAT 0x01 /* slave addr xfer done */

	#define MIE_MNRE 0x40 /* nack irq en */
	#define MIE_MALE 0x20 /* arblos irq en */
	#define MIE_MSTE 0x10 /* stop irq en */
	#define MIE_MDEE 0x08
	#define MIE_MDTE 0x04
	#define MIE_MDRE 0x02
	#define MIE_MATE 0x01 /* address sent irq en */

	#define FCR_RFRST 0x02 /* reset rx fifo */
	#define FCR_TFRST 0x01 /* reset tx fifo */

	#define FSR_TEND 0x04 /* last byte sent */
	#define FSR_RDF 0x02 /* rx fifo trigger */
	#define FSR_TDFE 0x01 /* tx fifo empty */

	#define FIER_TEIE 0x04 /* tx fifo empty irq en */
	#define FIER_RXIE 0x02 /* rx fifo trig irq en */
	#define FIER_TXIE 0x01 /* tx fifo trig irq en */

	#define FIFO_SIZE 16

	struct cami2c {
	void __iomem *iobase;
	struct i2c_adapter adap;

	/* message processing */
	struct i2c_msg *msg;
	#define IDF_SEND 1
	#define IDF_RECV 2
	#define IDF_STOP 4
	int flags;

	#define IDS_DONE 1
	#define IDS_ARBLOST 2
	#define IDS_NACK 4
	int status;
	struct completion xfer_done;

	int irq;
	struct resource *ioarea;
	};

	static inline void OUT32(struct cami2c *cam, int reg, unsigned long val)
	{
	ctrl_outl(val, (unsigned long)cam->iobase + reg);
	}

	static inline unsigned long IN32(struct cami2c *cam, int reg)
	{
	return ctrl_inl((unsigned long)cam->iobase + reg);
	}

	static irqreturn_t sh7760_i2c_irq(int irq, void *ptr)
	{
	struct cami2c *id = ptr;
	struct i2c_msg *msg = id->msg;
	char *data = msg->buf;
	unsigned long msr, fsr, fier, len;

	msr = IN32(id, I2CMSR);
	fsr = IN32(id, I2CFSR);

	/* arbitration lost */
	if (msr & MSR_MAL) {
	OUT32(id, I2CMCR, 0);
	OUT32(id, I2CSCR, 0);
	OUT32(id, I2CSAR, 0);
	id->status \|= IDS_DONE \| IDS_ARBLOST;
	goto out;
	}

	if (msr & MSR_MNR) {
	/* NACK handling is very screwed up. After receiving a
	* NAK IRQ one has to wait a bit before writing to any
	* registers, or the ctl will lock up. After that delay
	* do a normal i2c stop. Then wait at least 1 ms before
	* attempting another transfer or ctl will stop working
	*/
	udelay(100); /* wait or risk ctl hang */
	OUT32(id, I2CFCR, FCR_RFRST \| FCR_TFRST);
	OUT32(id, I2CMCR, MCR_MIE \| MCR_FSB);
	OUT32(id, I2CFIER, 0);
	OUT32(id, I2CMIER, MIE_MSTE);
	OUT32(id, I2CSCR, 0);
	OUT32(id, I2CSAR, 0);
	id->status \|= IDS_NACK;
	msr &= ~MSR_MAT;
	fsr = 0;
	/* In some cases the MST bit is also set. */
	}

	/* i2c-stop was sent */
	if (msr & MSR_MST) {
	id->status \|= IDS_DONE;
	goto out;
	}

	/* i2c slave addr was sent; set to "normal" operation */
	if (msr & MSR_MAT)
	OUT32(id, I2CMCR, MCR_MIE);

	fier = IN32(id, I2CFIER);

	if (fsr & FSR_RDF) {
	len = IN32(id, I2CRFDR);
	if (msg->len <= len) {
	if (id->flags & IDF_STOP) {
	OUT32(id, I2CMCR, MCR_MIE \| MCR_FSB);
	OUT32(id, I2CFIER, 0);
	/* manual says: wait >= 0.5 SCL times */
	udelay(5);
	/* next int should be MST */
	} else {
	id->status \|= IDS_DONE;
	/* keep the RDF bit: ctrl holds SCL low
	* until the setup for the next i2c_msg
	* clears this bit.
	*/
	fsr &= ~FSR_RDF;
	}
	}
	while (msg->len && len) {
	*data++ = IN32(id, I2CRXTX);
	msg->len--;
	len--;
	}

	if (msg->len) {
	len = (msg->len >= FIFO_SIZE) ? FIFO_SIZE - 1
	: msg->len - 1;

	OUT32(id, I2CFCR, FCR_TFRST \| ((len & 0xf) << 4));
	}

	} else if (id->flags & IDF_SEND) {
	if ((fsr & FSR_TEND) && (msg->len < 1)) {
	if (id->flags & IDF_STOP) {
	OUT32(id, I2CMCR, MCR_MIE \| MCR_FSB);
	} else {
	id->status \|= IDS_DONE;
	/* keep the TEND bit: ctl holds SCL low
	* until the setup for the next i2c_msg
	* clears this bit.
	*/
	fsr &= ~FSR_TEND;
	}
	}
	if (fsr & FSR_TDFE) {
	while (msg->len && (IN32(id, I2CTFDR) < FIFO_SIZE)) {
	OUT32(id, I2CRXTX, *data++);
	msg->len--;
	}

	if (msg->len < 1) {
	fier &= ~FIER_TXIE;
	OUT32(id, I2CFIER, fier);
	} else {
	len = (msg->len >= FIFO_SIZE) ? 2 : 0;
	OUT32(id, I2CFCR,
	FCR_RFRST \| ((len & 3) << 2));
	}
	}
	}
	out:
	if (id->status & IDS_DONE) {
	OUT32(id, I2CMIER, 0);
	OUT32(id, I2CFIER, 0);
	id->msg = NULL;
	complete(&id->xfer_done);
	}
	/* clear status flags and ctrl resumes work */
	OUT32(id, I2CMSR, ~msr);
	OUT32(id, I2CFSR, ~fsr);
	OUT32(id, I2CSSR, 0);

	return IRQ_HANDLED;
	}


	/* prepare and start a master receive operation */
	static void sh7760_i2c_mrecv(struct cami2c *id)
	{
	int len;

	id->flags \|= IDF_RECV;

	/* set the slave addr reg; otherwise rcv wont work! */
	OUT32(id, I2CSAR, 0xfe);
	OUT32(id, I2CMAR, (id->msg->addr << 1) \| 1);

	/* adjust rx fifo trigger */
	if (id->msg->len >= FIFO_SIZE)
	len = FIFO_SIZE - 1; /* trigger at fifo full */
	else
	len = id->msg->len - 1; /* trigger before all received */

	OUT32(id, I2CFCR, FCR_RFRST \| FCR_TFRST);
	OUT32(id, I2CFCR, FCR_TFRST \| ((len & 0xF) << 4));

	OUT32(id, I2CMSR, 0);
	OUT32(id, I2CMCR, MCR_MIE \| MCR_ESG);
	OUT32(id, I2CMIER, MIE_MNRE \| MIE_MALE \| MIE_MSTE \| MIE_MATE);
	OUT32(id, I2CFIER, FIER_RXIE);
	}

	/* prepare and start a master send operation */
	static void sh7760_i2c_msend(struct cami2c *id)
	{
	int len;

	id->flags \|= IDF_SEND;

	/* set the slave addr reg; otherwise xmit wont work! */
	OUT32(id, I2CSAR, 0xfe);
	OUT32(id, I2CMAR, (id->msg->addr << 1) \| 0);

	/* adjust tx fifo trigger */
	if (id->msg->len >= FIFO_SIZE)
	len = 2; /* trig: 2 bytes left in TX fifo */
	else
	len = 0; /* trig: 8 bytes left in TX fifo */

	OUT32(id, I2CFCR, FCR_RFRST \| FCR_TFRST);
	OUT32(id, I2CFCR, FCR_RFRST \| ((len & 3) << 2));

	while (id->msg->len && IN32(id, I2CTFDR) < FIFO_SIZE) {
	OUT32(id, I2CRXTX, *(id->msg->buf));
	(id->msg->len)--;
	(id->msg->buf)++;
	}

	OUT32(id, I2CMSR, 0);
	OUT32(id, I2CMCR, MCR_MIE \| MCR_ESG);
	OUT32(id, I2CFSR, 0);
	OUT32(id, I2CMIER, MIE_MNRE \| MIE_MALE \| MIE_MSTE \| MIE_MATE);
	OUT32(id, I2CFIER, FIER_TEIE \| (id->msg->len ? FIER_TXIE : 0));
	}

	static inline int sh7760_i2c_busy_check(struct cami2c *id)
	{
	return (IN32(id, I2CMCR) & MCR_FSDA);
	}

	static int sh7760_i2c_master_xfer(struct i2c_adapter *adap,
	struct i2c_msg *msgs,
	int num)
	{
	struct cami2c *id = adap->algo_data;
	int i, retr;

	if (sh7760_i2c_busy_check(id)) {
	dev_err(&adap->dev, "sh7760-i2c%d: bus busy!\n", adap->nr);
	return -EBUSY;
	}

	i = 0;
	while (i < num) {
	retr = adap->retries;
	retry:
	id->flags = ((i == (num-1)) ? IDF_STOP : 0);
	id->status = 0;
	id->msg = msgs;
	init_completion(&id->xfer_done);

	if (msgs->flags & I2C_M_RD)
	sh7760_i2c_mrecv(id);
	else
	sh7760_i2c_msend(id);

	wait_for_completion(&id->xfer_done);

	if (id->status == 0) {
	num = -EIO;
	break;
	}

	if (id->status & IDS_NACK) {
	/* wait a bit or i2c module stops working */
	mdelay(1);
	num = -EREMOTEIO;
	break;
	}

	if (id->status & IDS_ARBLOST) {
	if (retr--) {
	mdelay(2);
	goto retry;
	}
	num = -EREMOTEIO;
	break;
	}

	msgs++;
	i++;
	}

	id->msg = NULL;
	id->flags = 0;
	id->status = 0;

	OUT32(id, I2CMCR, 0);
	OUT32(id, I2CMSR, 0);
	OUT32(id, I2CMIER, 0);
	OUT32(id, I2CFIER, 0);

	/* reset slave module registers too: master mode enables slave
	* module for receive ops (ack, data). Without this reset,
	* eternal bus activity might be reported after NACK / ARBLOST.
	*/
	OUT32(id, I2CSCR, 0);
	OUT32(id, I2CSAR, 0);
	OUT32(id, I2CSSR, 0);

	return num;
	}

	static u32 sh7760_i2c_func(struct i2c_adapter *adap)
	{
	return I2C_FUNC_I2C \| (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
	}

	static const struct i2c_algorithm sh7760_i2c_algo = {
	.master_xfer = sh7760_i2c_master_xfer,
	.functionality = sh7760_i2c_func,
	};

	/* calculate CCR register setting for a desired scl clock. SCL clock is
	* derived from I2C module clock (iclk) which in turn is derived from
	* peripheral module clock (mclk, usually around 33MHz):
	* iclk = mclk/(CDF + 1). iclk must be < 20MHz.
	* scl = iclk/(SCGD*8 + 20).
	*/
	static int __devinit calc_CCR(unsigned long scl_hz)
	{
	struct clk *mclk;
	unsigned long mck, m1, dff, odff, iclk;
	signed char cdf, cdfm;
	int scgd, scgdm, scgds;

	mclk = clk_get(NULL, "peripheral_clk");
	if (IS_ERR(mclk)) {
	return PTR_ERR(mclk);
	} else {
	mck = mclk->rate;
	clk_put(mclk);
	}

	odff = scl_hz;
	scgdm = cdfm = m1 = 0;
	for (cdf = 3; cdf >= 0; cdf--) {
	iclk = mck / (1 + cdf);
	if (iclk >= 20000000)
	continue;
	scgds = ((iclk / scl_hz) - 20) >> 3;
	for (scgd = scgds; (scgd < 63) && scgd <= scgds + 1; scgd++) {
	m1 = iclk / (20 + (scgd << 3));
	dff = abs(scl_hz - m1);
	if (dff < odff) {
	odff = dff;
	cdfm = cdf;
	scgdm = scgd;
	}
	}
	}
	/* fail if more than 25% off of requested SCL */
	if (odff > (scl_hz >> 2))
	return -EINVAL;

	/* create a CCR register value */
	return ((scgdm << 2) \| cdfm);
	}

	static int __devinit sh7760_i2c_probe(struct platform_device *pdev)
	{
	struct sh7760_i2c_platdata *pd;
	struct resource *res;
	struct cami2c *id;
	int ret;

	pd = pdev->dev.platform_data;
	if (!pd) {
	dev_err(&pdev->dev, "no platform_data!\n");
	ret = -ENODEV;
	goto out0;
	}

	id = kzalloc(sizeof(struct cami2c), GFP_KERNEL);
	if (!id) {
	dev_err(&pdev->dev, "no mem for private data\n");
	ret = -ENOMEM;
	goto out0;
	}

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (!res) {
	dev_err(&pdev->dev, "no mmio resources\n");
	ret = -ENODEV;
	goto out1;
	}

	id->ioarea = request_mem_region(res->start, REGSIZE, pdev->name);
	if (!id->ioarea) {
	dev_err(&pdev->dev, "mmio already reserved\n");
	ret = -EBUSY;
	goto out1;
	}

	id->iobase = ioremap(res->start, REGSIZE);
	if (!id->iobase) {
	dev_err(&pdev->dev, "cannot ioremap\n");
	ret = -ENODEV;
	goto out2;
	}

	id->irq = platform_get_irq(pdev, 0);

	id->adap.nr = pdev->id;
	id->adap.algo = &sh7760_i2c_algo;
	id->adap.class = I2C_CLASS_HWMON \| I2C_CLASS_SPD;
	id->adap.retries = 3;
	id->adap.algo_data = id;
	id->adap.dev.parent = &pdev->dev;
	snprintf(id->adap.name, sizeof(id->adap.name),
	"SH7760 I2C at %08lx", (unsigned long)res->start);

	OUT32(id, I2CMCR, 0);
	OUT32(id, I2CMSR, 0);
	OUT32(id, I2CMIER, 0);
	OUT32(id, I2CMAR, 0);
	OUT32(id, I2CSIER, 0);
	OUT32(id, I2CSAR, 0);
	OUT32(id, I2CSCR, 0);
	OUT32(id, I2CSSR, 0);
	OUT32(id, I2CFIER, 0);
	OUT32(id, I2CFCR, FCR_RFRST \| FCR_TFRST);
	OUT32(id, I2CFSR, 0);

	ret = calc_CCR(pd->speed_khz * 1000);
	if (ret < 0) {
	dev_err(&pdev->dev, "invalid SCL clock: %dkHz\n",
	pd->speed_khz);
	goto out3;
	}
	OUT32(id, I2CCCR, ret);

	if (request_irq(id->irq, sh7760_i2c_irq, IRQF_DISABLED,
	SH7760_I2C_DEVNAME, id)) {
	dev_err(&pdev->dev, "cannot get irq %d\n", id->irq);
	ret = -EBUSY;
	goto out3;
	}

	ret = i2c_add_numbered_adapter(&id->adap);
	if (ret < 0) {
	dev_err(&pdev->dev, "reg adap failed: %d\n", ret);
	goto out4;
	}

	platform_set_drvdata(pdev, id);

	dev_info(&pdev->dev, "%d kHz mmio %08x irq %d\n",
	pd->speed_khz, res->start, id->irq);

	return 0;

	out4:
	free_irq(id->irq, id);
	out3:
	iounmap(id->iobase);
	out2:
	release_resource(id->ioarea);
	kfree(id->ioarea);
	out1:
	kfree(id);
	out0:
	return ret;
	}

	static int __devexit sh7760_i2c_remove(struct platform_device *pdev)
	{
	struct cami2c *id = platform_get_drvdata(pdev);

	i2c_del_adapter(&id->adap);
	free_irq(id->irq, id);
	iounmap(id->iobase);
	release_resource(id->ioarea);
	kfree(id->ioarea);
	kfree(id);
	platform_set_drvdata(pdev, NULL);

	return 0;
	}

	static struct platform_driver sh7760_i2c_drv = {
	.driver = {
	.name = SH7760_I2C_DEVNAME,
	.owner = THIS_MODULE,
	},
	.probe = sh7760_i2c_probe,
	.remove = __devexit_p(sh7760_i2c_remove),
	};

	static int __init sh7760_i2c_init(void)
	{
	return platform_driver_register(&sh7760_i2c_drv);
	}

	static void __exit sh7760_i2c_exit(void)
	{
	platform_driver_unregister(&sh7760_i2c_drv);
	}

	module_init(sh7760_i2c_init);
	module_exit(sh7760_i2c_exit);

	MODULE_LICENSE("GPL");
	MODULE_DESCRIPTION("SH7760 I2C bus driver");
	MODULE_AUTHOR("Manuel Lauss <mano@roarinelk.homelinux.net>");