xref: /openbmc/linux/drivers/i2c/busses/i2c-davinci.c (revision 35780e860f7d4a5f33f6ceadf09038ee26f1ef43)

/*
 * TI DAVINCI I2C adapter driver.
 *
 * Copyright (C) 2006 Texas Instruments.
 * Copyright (C) 2007 MontaVista Software Inc.
 *
 * Updated by Vinod & Sudhakar Feb 2005
 *
 * ----------------------------------------------------------------------------
 *
 * 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, or
 * (at your option) any later version.
 *
 * 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/kernel.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/clk.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/cpufreq.h>
#include <linux/gpio.h>
#include <linux/of_device.h>
#include <linux/platform_data/i2c-davinci.h>

/* ----- global defines ----------------------------------------------- */

#define DAVINCI_I2C_TIMEOUT	(1*HZ)
#define DAVINCI_I2C_MAX_TRIES	2
#define DAVINCI_I2C_OWN_ADDRESS	0x08
#define I2C_DAVINCI_INTR_ALL    (DAVINCI_I2C_IMR_SCD | \
				 DAVINCI_I2C_IMR_ARDY | \
				 DAVINCI_I2C_IMR_NACK | \
				 DAVINCI_I2C_IMR_AL)

#define DAVINCI_I2C_OAR_REG	0x00
#define DAVINCI_I2C_IMR_REG	0x04
#define DAVINCI_I2C_STR_REG	0x08
#define DAVINCI_I2C_CLKL_REG	0x0c
#define DAVINCI_I2C_CLKH_REG	0x10
#define DAVINCI_I2C_CNT_REG	0x14
#define DAVINCI_I2C_DRR_REG	0x18
#define DAVINCI_I2C_SAR_REG	0x1c
#define DAVINCI_I2C_DXR_REG	0x20
#define DAVINCI_I2C_MDR_REG	0x24
#define DAVINCI_I2C_IVR_REG	0x28
#define DAVINCI_I2C_EMDR_REG	0x2c
#define DAVINCI_I2C_PSC_REG	0x30
#define DAVINCI_I2C_FUNC_REG	0x48
#define DAVINCI_I2C_DIR_REG	0x4c
#define DAVINCI_I2C_DIN_REG	0x50
#define DAVINCI_I2C_DOUT_REG	0x54
#define DAVINCI_I2C_DSET_REG	0x58
#define DAVINCI_I2C_DCLR_REG	0x5c

#define DAVINCI_I2C_IVR_AAS	0x07
#define DAVINCI_I2C_IVR_SCD	0x06
#define DAVINCI_I2C_IVR_XRDY	0x05
#define DAVINCI_I2C_IVR_RDR	0x04
#define DAVINCI_I2C_IVR_ARDY	0x03
#define DAVINCI_I2C_IVR_NACK	0x02
#define DAVINCI_I2C_IVR_AL	0x01

#define DAVINCI_I2C_STR_BB	BIT(12)
#define DAVINCI_I2C_STR_RSFULL	BIT(11)
#define DAVINCI_I2C_STR_SCD	BIT(5)
#define DAVINCI_I2C_STR_ARDY	BIT(2)
#define DAVINCI_I2C_STR_NACK	BIT(1)
#define DAVINCI_I2C_STR_AL	BIT(0)

#define DAVINCI_I2C_MDR_NACK	BIT(15)
#define DAVINCI_I2C_MDR_STT	BIT(13)
#define DAVINCI_I2C_MDR_STP	BIT(11)
#define DAVINCI_I2C_MDR_MST	BIT(10)
#define DAVINCI_I2C_MDR_TRX	BIT(9)
#define DAVINCI_I2C_MDR_XA	BIT(8)
#define DAVINCI_I2C_MDR_RM	BIT(7)
#define DAVINCI_I2C_MDR_IRS	BIT(5)

#define DAVINCI_I2C_IMR_AAS	BIT(6)
#define DAVINCI_I2C_IMR_SCD	BIT(5)
#define DAVINCI_I2C_IMR_XRDY	BIT(4)
#define DAVINCI_I2C_IMR_RRDY	BIT(3)
#define DAVINCI_I2C_IMR_ARDY	BIT(2)
#define DAVINCI_I2C_IMR_NACK	BIT(1)
#define DAVINCI_I2C_IMR_AL	BIT(0)

/* set SDA and SCL as GPIO */
#define DAVINCI_I2C_FUNC_PFUNC0	BIT(0)

/* set SCL as output when used as GPIO*/
#define DAVINCI_I2C_DIR_PDIR0	BIT(0)
/* set SDA as output when used as GPIO*/
#define DAVINCI_I2C_DIR_PDIR1	BIT(1)

/* read SCL GPIO level */
#define DAVINCI_I2C_DIN_PDIN0 BIT(0)
/* read SDA GPIO level */
#define DAVINCI_I2C_DIN_PDIN1 BIT(1)

/*set the SCL GPIO high */
#define DAVINCI_I2C_DSET_PDSET0	BIT(0)
/*set the SDA GPIO high */
#define DAVINCI_I2C_DSET_PDSET1	BIT(1)

/* set the SCL GPIO low */
#define DAVINCI_I2C_DCLR_PDCLR0	BIT(0)
/* set the SDA GPIO low */
#define DAVINCI_I2C_DCLR_PDCLR1	BIT(1)

struct davinci_i2c_dev {
	struct device           *dev;
	void __iomem		*base;
	struct completion	cmd_complete;
	struct clk              *clk;
	int			cmd_err;
	u8			*buf;
	size_t			buf_len;
	int			irq;
	int			stop;
	u8			terminate;
	struct i2c_adapter	adapter;
#ifdef CONFIG_CPU_FREQ
	struct completion	xfr_complete;
	struct notifier_block	freq_transition;
#endif
	struct davinci_i2c_platform_data *pdata;
};

/* default platform data to use if not supplied in the platform_device */
static struct davinci_i2c_platform_data davinci_i2c_platform_data_default = {
	.bus_freq	= 100,
	.bus_delay	= 0,
};

static inline void davinci_i2c_write_reg(struct davinci_i2c_dev *i2c_dev,
					 int reg, u16 val)
{
	writew_relaxed(val, i2c_dev->base + reg);
}

static inline u16 davinci_i2c_read_reg(struct davinci_i2c_dev *i2c_dev, int reg)
{
	return readw_relaxed(i2c_dev->base + reg);
}

static inline void davinci_i2c_reset_ctrl(struct davinci_i2c_dev *i2c_dev,
								int val)
{
	u16 w;

	w = davinci_i2c_read_reg(i2c_dev, DAVINCI_I2C_MDR_REG);
	if (!val)	/* put I2C into reset */
		w &= ~DAVINCI_I2C_MDR_IRS;
	else		/* take I2C out of reset */
		w |= DAVINCI_I2C_MDR_IRS;

	davinci_i2c_write_reg(i2c_dev, DAVINCI_I2C_MDR_REG, w);
}

static void i2c_davinci_calc_clk_dividers(struct davinci_i2c_dev *dev)
{
	struct davinci_i2c_platform_data *pdata = dev->pdata;
	u16 psc;
	u32 clk;
	u32 d;
	u32 clkh;
	u32 clkl;
	u32 input_clock = clk_get_rate(dev->clk);
	struct device_node *of_node = dev->dev->of_node;

	/* NOTE: I2C Clock divider programming info
	 * As per I2C specs the following formulas provide prescaler
	 * and low/high divider values
	 * input clk --> PSC Div -----------> ICCL/H Div --> output clock
	 *                       module clk
	 *
	 * output clk = module clk / (PSC + 1) [ (ICCL + d) + (ICCH + d) ]
	 *
	 * Thus,
	 * (ICCL + ICCH) = clk = (input clk / ((psc +1) * output clk)) - 2d;
	 *
	 * where if PSC == 0, d = 7,
	 *       if PSC == 1, d = 6
	 *       if PSC > 1 , d = 5
	 *
	 * Note:
	 * d is always 6 on Keystone I2C controller
	 */

	/* get minimum of 7 MHz clock, but max of 12 MHz */
	psc = (input_clock / 7000000) - 1;
	if ((input_clock / (psc + 1)) > 12000000)
		psc++;	/* better to run under spec than over */
	d = (psc >= 2) ? 5 : 7 - psc;

	if (of_node && of_device_is_compatible(of_node, "ti,keystone-i2c"))
		d = 6;

	clk = ((input_clock / (psc + 1)) / (pdata->bus_freq * 1000));
	/* Avoid driving the bus too fast because of rounding errors above */
	if (input_clock / (psc + 1) / clk > pdata->bus_freq * 1000)
		clk++;
	/*
	 * According to I2C-BUS Spec 2.1, in FAST-MODE LOW period should be at
	 * least 1.3uS, which is not the case with 50% duty cycle. Driving HIGH
	 * to LOW ratio as 1 to 2 is more safe.
	 */
	if (pdata->bus_freq > 100)
		clkl = (clk << 1) / 3;
	else
		clkl = (clk >> 1);
	/*
	 * It's not always possible to have 1 to 2 ratio when d=7, so fall back
	 * to minimal possible clkh in this case.
	 */
	if (clk >= clkl + d) {
		clkh = clk - clkl - d;
		clkl -= d;
	} else {
		clkh = 0;
		clkl = clk - (d << 1);
	}

	davinci_i2c_write_reg(dev, DAVINCI_I2C_PSC_REG, psc);
	davinci_i2c_write_reg(dev, DAVINCI_I2C_CLKH_REG, clkh);
	davinci_i2c_write_reg(dev, DAVINCI_I2C_CLKL_REG, clkl);

	dev_dbg(dev->dev, "input_clock = %d, CLK = %d\n", input_clock, clk);
}

/*
 * This function configures I2C and brings I2C out of reset.
 * This function is called during I2C init function. This function
 * also gets called if I2C encounters any errors.
 */
static int i2c_davinci_init(struct davinci_i2c_dev *dev)
{
	struct davinci_i2c_platform_data *pdata = dev->pdata;

	/* put I2C into reset */
	davinci_i2c_reset_ctrl(dev, 0);

	/* compute clock dividers */
	i2c_davinci_calc_clk_dividers(dev);

	/* Respond at reserved "SMBus Host" slave address" (and zero);
	 * we seem to have no option to not respond...
	 */
	davinci_i2c_write_reg(dev, DAVINCI_I2C_OAR_REG, DAVINCI_I2C_OWN_ADDRESS);

	dev_dbg(dev->dev, "PSC  = %d\n",
		davinci_i2c_read_reg(dev, DAVINCI_I2C_PSC_REG));
	dev_dbg(dev->dev, "CLKL = %d\n",
		davinci_i2c_read_reg(dev, DAVINCI_I2C_CLKL_REG));
	dev_dbg(dev->dev, "CLKH = %d\n",
		davinci_i2c_read_reg(dev, DAVINCI_I2C_CLKH_REG));
	dev_dbg(dev->dev, "bus_freq = %dkHz, bus_delay = %d\n",
		pdata->bus_freq, pdata->bus_delay);


	/* Take the I2C module out of reset: */
	davinci_i2c_reset_ctrl(dev, 1);

	/* Enable interrupts */
	davinci_i2c_write_reg(dev, DAVINCI_I2C_IMR_REG, I2C_DAVINCI_INTR_ALL);

	return 0;
}

/*
 * This routine does i2c bus recovery by using i2c_generic_gpio_recovery
 * which is provided by I2C Bus recovery infrastructure.
 */
static void davinci_i2c_prepare_recovery(struct i2c_adapter *adap)
{
	struct davinci_i2c_dev *dev = i2c_get_adapdata(adap);

	/* Disable interrupts */
	davinci_i2c_write_reg(dev, DAVINCI_I2C_IMR_REG, 0);

	/* put I2C into reset */
	davinci_i2c_reset_ctrl(dev, 0);
}

static void davinci_i2c_unprepare_recovery(struct i2c_adapter *adap)
{
	struct davinci_i2c_dev *dev = i2c_get_adapdata(adap);

	i2c_davinci_init(dev);
}

static struct i2c_bus_recovery_info davinci_i2c_gpio_recovery_info = {
	.recover_bus = i2c_generic_gpio_recovery,
	.prepare_recovery = davinci_i2c_prepare_recovery,
	.unprepare_recovery = davinci_i2c_unprepare_recovery,
};

static void davinci_i2c_set_scl(struct i2c_adapter *adap, int val)
{
	struct davinci_i2c_dev *dev = i2c_get_adapdata(adap);

	if (val)
		davinci_i2c_write_reg(dev, DAVINCI_I2C_DSET_REG,
				      DAVINCI_I2C_DSET_PDSET0);
	else
		davinci_i2c_write_reg(dev, DAVINCI_I2C_DCLR_REG,
				      DAVINCI_I2C_DCLR_PDCLR0);
}

static int davinci_i2c_get_scl(struct i2c_adapter *adap)
{
	struct davinci_i2c_dev *dev = i2c_get_adapdata(adap);
	int val;

	/* read the state of SCL */
	val = davinci_i2c_read_reg(dev, DAVINCI_I2C_DIN_REG);
	return val & DAVINCI_I2C_DIN_PDIN0;
}

static int davinci_i2c_get_sda(struct i2c_adapter *adap)
{
	struct davinci_i2c_dev *dev = i2c_get_adapdata(adap);
	int val;

	/* read the state of SDA */
	val = davinci_i2c_read_reg(dev, DAVINCI_I2C_DIN_REG);
	return val & DAVINCI_I2C_DIN_PDIN1;
}

static void davinci_i2c_scl_prepare_recovery(struct i2c_adapter *adap)
{
	struct davinci_i2c_dev *dev = i2c_get_adapdata(adap);

	davinci_i2c_prepare_recovery(adap);

	/* SCL output, SDA input */
	davinci_i2c_write_reg(dev, DAVINCI_I2C_DIR_REG, DAVINCI_I2C_DIR_PDIR0);

	/* change to GPIO mode */
	davinci_i2c_write_reg(dev, DAVINCI_I2C_FUNC_REG,
			      DAVINCI_I2C_FUNC_PFUNC0);
}

static void davinci_i2c_scl_unprepare_recovery(struct i2c_adapter *adap)
{
	struct davinci_i2c_dev *dev = i2c_get_adapdata(adap);

	/* change back to I2C mode */
	davinci_i2c_write_reg(dev, DAVINCI_I2C_FUNC_REG, 0);

	davinci_i2c_unprepare_recovery(adap);
}

static struct i2c_bus_recovery_info davinci_i2c_scl_recovery_info = {
	.recover_bus = i2c_generic_scl_recovery,
	.set_scl = davinci_i2c_set_scl,
	.get_scl = davinci_i2c_get_scl,
	.get_sda = davinci_i2c_get_sda,
	.prepare_recovery = davinci_i2c_scl_prepare_recovery,
	.unprepare_recovery = davinci_i2c_scl_unprepare_recovery,
};

/*
 * Waiting for bus not busy
 */
static int i2c_davinci_wait_bus_not_busy(struct davinci_i2c_dev *dev)
{
	unsigned long timeout = jiffies + dev->adapter.timeout;

	do {
		if (!(davinci_i2c_read_reg(dev, DAVINCI_I2C_STR_REG) & DAVINCI_I2C_STR_BB))
			return 0;
		schedule_timeout_uninterruptible(1);
	} while (time_before_eq(jiffies, timeout));

	dev_warn(dev->dev, "timeout waiting for bus ready\n");
	i2c_recover_bus(&dev->adapter);

	/*
	 * if bus is still "busy" here, it's most probably a HW problem like
	 * short-circuit
	 */
	if (davinci_i2c_read_reg(dev, DAVINCI_I2C_STR_REG) & DAVINCI_I2C_STR_BB)
		return -EIO;

	return 0;
}

/*
 * Low level master read/write transaction. This function is called
 * from i2c_davinci_xfer.
 */
static int
i2c_davinci_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg, int stop)
{
	struct davinci_i2c_dev *dev = i2c_get_adapdata(adap);
	struct davinci_i2c_platform_data *pdata = dev->pdata;
	u32 flag;
	u16 w;
	unsigned long time_left;

	if (msg->addr == DAVINCI_I2C_OWN_ADDRESS) {
		dev_warn(dev->dev, "transfer to own address aborted\n");
		return -EADDRNOTAVAIL;
	}

	/* Introduce a delay, required for some boards (e.g Davinci EVM) */
	if (pdata->bus_delay)
		udelay(pdata->bus_delay);

	/* set the slave address */
	davinci_i2c_write_reg(dev, DAVINCI_I2C_SAR_REG, msg->addr);

	dev->buf = msg->buf;
	dev->buf_len = msg->len;
	dev->stop = stop;

	davinci_i2c_write_reg(dev, DAVINCI_I2C_CNT_REG, dev->buf_len);

	reinit_completion(&dev->cmd_complete);
	dev->cmd_err = 0;

	/* Take I2C out of reset and configure it as master */
	flag = DAVINCI_I2C_MDR_IRS | DAVINCI_I2C_MDR_MST;

	/* if the slave address is ten bit address, enable XA bit */
	if (msg->flags & I2C_M_TEN)
		flag |= DAVINCI_I2C_MDR_XA;
	if (!(msg->flags & I2C_M_RD))
		flag |= DAVINCI_I2C_MDR_TRX;
	if (msg->len == 0)
		flag |= DAVINCI_I2C_MDR_RM;

	/* Enable receive or transmit interrupts */
	w = davinci_i2c_read_reg(dev, DAVINCI_I2C_IMR_REG);
	if (msg->flags & I2C_M_RD)
		w |= DAVINCI_I2C_IMR_RRDY;
	else
		w |= DAVINCI_I2C_IMR_XRDY;
	davinci_i2c_write_reg(dev, DAVINCI_I2C_IMR_REG, w);

	dev->terminate = 0;

	/*
	 * Write mode register first as needed for correct behaviour
	 * on OMAP-L138, but don't set STT yet to avoid a race with XRDY
	 * occurring before we have loaded DXR
	 */
	davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, flag);

	/*
	 * First byte should be set here, not after interrupt,
	 * because transmit-data-ready interrupt can come before
	 * NACK-interrupt during sending of previous message and
	 * ICDXR may have wrong data
	 * It also saves us one interrupt, slightly faster
	 */
	if ((!(msg->flags & I2C_M_RD)) && dev->buf_len) {
		davinci_i2c_write_reg(dev, DAVINCI_I2C_DXR_REG, *dev->buf++);
		dev->buf_len--;
	}

	/* Set STT to begin transmit now DXR is loaded */
	flag |= DAVINCI_I2C_MDR_STT;
	if (stop && msg->len != 0)
		flag |= DAVINCI_I2C_MDR_STP;
	davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, flag);

	time_left = wait_for_completion_timeout(&dev->cmd_complete,
						dev->adapter.timeout);
	if (!time_left) {
		dev_err(dev->dev, "controller timed out\n");
		i2c_recover_bus(adap);
		dev->buf_len = 0;
		return -ETIMEDOUT;
	}
	if (dev->buf_len) {
		/* This should be 0 if all bytes were transferred
		 * or dev->cmd_err denotes an error.
		 */
		dev_err(dev->dev, "abnormal termination buf_len=%i\n",
			dev->buf_len);
		dev->terminate = 1;
		wmb();
		dev->buf_len = 0;
		return -EREMOTEIO;
	}

	/* no error */
	if (likely(!dev->cmd_err))
		return msg->len;

	/* We have an error */
	if (dev->cmd_err & DAVINCI_I2C_STR_AL) {
		i2c_davinci_init(dev);
		return -EIO;
	}

	if (dev->cmd_err & DAVINCI_I2C_STR_NACK) {
		if (msg->flags & I2C_M_IGNORE_NAK)
			return msg->len;
		w = davinci_i2c_read_reg(dev, DAVINCI_I2C_MDR_REG);
		w |= DAVINCI_I2C_MDR_STP;
		davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, w);
		return -EREMOTEIO;
	}
	return -EIO;
}

/*
 * Prepare controller for a transaction and call i2c_davinci_xfer_msg
 */
static int
i2c_davinci_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
{
	struct davinci_i2c_dev *dev = i2c_get_adapdata(adap);
	int i;
	int ret;

	dev_dbg(dev->dev, "%s: msgs: %d\n", __func__, num);

	ret = i2c_davinci_wait_bus_not_busy(dev);
	if (ret < 0) {
		dev_warn(dev->dev, "timeout waiting for bus ready\n");
		return ret;
	}

	for (i = 0; i < num; i++) {
		ret = i2c_davinci_xfer_msg(adap, &msgs[i], (i == (num - 1)));
		dev_dbg(dev->dev, "%s [%d/%d] ret: %d\n", __func__, i + 1, num,
			ret);
		if (ret < 0)
			return ret;
	}

#ifdef CONFIG_CPU_FREQ
	complete(&dev->xfr_complete);
#endif

	return num;
}

static u32 i2c_davinci_func(struct i2c_adapter *adap)
{
	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}

static void terminate_read(struct davinci_i2c_dev *dev)
{
	u16 w = davinci_i2c_read_reg(dev, DAVINCI_I2C_MDR_REG);
	w |= DAVINCI_I2C_MDR_NACK;
	davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, w);

	/* Throw away data */
	davinci_i2c_read_reg(dev, DAVINCI_I2C_DRR_REG);
	if (!dev->terminate)
		dev_err(dev->dev, "RDR IRQ while no data requested\n");
}
static void terminate_write(struct davinci_i2c_dev *dev)
{
	u16 w = davinci_i2c_read_reg(dev, DAVINCI_I2C_MDR_REG);
	w |= DAVINCI_I2C_MDR_RM | DAVINCI_I2C_MDR_STP;
	davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, w);

	if (!dev->terminate)
		dev_dbg(dev->dev, "TDR IRQ while no data to send\n");
}

/*
 * Interrupt service routine. This gets called whenever an I2C interrupt
 * occurs.
 */
static irqreturn_t i2c_davinci_isr(int this_irq, void *dev_id)
{
	struct davinci_i2c_dev *dev = dev_id;
	u32 stat;
	int count = 0;
	u16 w;

	while ((stat = davinci_i2c_read_reg(dev, DAVINCI_I2C_IVR_REG))) {
		dev_dbg(dev->dev, "%s: stat=0x%x\n", __func__, stat);
		if (count++ == 100) {
			dev_warn(dev->dev, "Too much work in one IRQ\n");
			break;
		}

		switch (stat) {
		case DAVINCI_I2C_IVR_AL:
			/* Arbitration lost, must retry */
			dev->cmd_err |= DAVINCI_I2C_STR_AL;
			dev->buf_len = 0;
			complete(&dev->cmd_complete);
			break;

		case DAVINCI_I2C_IVR_NACK:
			dev->cmd_err |= DAVINCI_I2C_STR_NACK;
			dev->buf_len = 0;
			complete(&dev->cmd_complete);
			break;

		case DAVINCI_I2C_IVR_ARDY:
			davinci_i2c_write_reg(dev,
				DAVINCI_I2C_STR_REG, DAVINCI_I2C_STR_ARDY);
			if (((dev->buf_len == 0) && (dev->stop != 0)) ||
			    (dev->cmd_err & DAVINCI_I2C_STR_NACK)) {
				w = davinci_i2c_read_reg(dev,
							 DAVINCI_I2C_MDR_REG);
				w |= DAVINCI_I2C_MDR_STP;
				davinci_i2c_write_reg(dev,
						      DAVINCI_I2C_MDR_REG, w);
			}
			complete(&dev->cmd_complete);
			break;

		case DAVINCI_I2C_IVR_RDR:
			if (dev->buf_len) {
				*dev->buf++ =
				    davinci_i2c_read_reg(dev,
							 DAVINCI_I2C_DRR_REG);
				dev->buf_len--;
				if (dev->buf_len)
					continue;

				davinci_i2c_write_reg(dev,
					DAVINCI_I2C_STR_REG,
					DAVINCI_I2C_IMR_RRDY);
			} else {
				/* signal can terminate transfer */
				terminate_read(dev);
			}
			break;

		case DAVINCI_I2C_IVR_XRDY:
			if (dev->buf_len) {
				davinci_i2c_write_reg(dev, DAVINCI_I2C_DXR_REG,
						      *dev->buf++);
				dev->buf_len--;
				if (dev->buf_len)
					continue;

				w = davinci_i2c_read_reg(dev,
							 DAVINCI_I2C_IMR_REG);
				w &= ~DAVINCI_I2C_IMR_XRDY;
				davinci_i2c_write_reg(dev,
						      DAVINCI_I2C_IMR_REG,
						      w);
			} else {
				/* signal can terminate transfer */
				terminate_write(dev);
			}
			break;

		case DAVINCI_I2C_IVR_SCD:
			davinci_i2c_write_reg(dev,
				DAVINCI_I2C_STR_REG, DAVINCI_I2C_STR_SCD);
			complete(&dev->cmd_complete);
			break;

		case DAVINCI_I2C_IVR_AAS:
			dev_dbg(dev->dev, "Address as slave interrupt\n");
			break;

		default:
			dev_warn(dev->dev, "Unrecognized irq stat %d\n", stat);
			break;
		}
	}

	return count ? IRQ_HANDLED : IRQ_NONE;
}

#ifdef CONFIG_CPU_FREQ
static int i2c_davinci_cpufreq_transition(struct notifier_block *nb,
				     unsigned long val, void *data)
{
	struct davinci_i2c_dev *dev;

	dev = container_of(nb, struct davinci_i2c_dev, freq_transition);
	if (val == CPUFREQ_PRECHANGE) {
		wait_for_completion(&dev->xfr_complete);
		davinci_i2c_reset_ctrl(dev, 0);
	} else if (val == CPUFREQ_POSTCHANGE) {
		i2c_davinci_calc_clk_dividers(dev);
		davinci_i2c_reset_ctrl(dev, 1);
	}

	return 0;
}

static inline int i2c_davinci_cpufreq_register(struct davinci_i2c_dev *dev)
{
	dev->freq_transition.notifier_call = i2c_davinci_cpufreq_transition;

	return cpufreq_register_notifier(&dev->freq_transition,
					 CPUFREQ_TRANSITION_NOTIFIER);
}

static inline void i2c_davinci_cpufreq_deregister(struct davinci_i2c_dev *dev)
{
	cpufreq_unregister_notifier(&dev->freq_transition,
				    CPUFREQ_TRANSITION_NOTIFIER);
}
#else
static inline int i2c_davinci_cpufreq_register(struct davinci_i2c_dev *dev)
{
	return 0;
}

static inline void i2c_davinci_cpufreq_deregister(struct davinci_i2c_dev *dev)
{
}
#endif

static struct i2c_algorithm i2c_davinci_algo = {
	.master_xfer	= i2c_davinci_xfer,
	.functionality	= i2c_davinci_func,
};

static const struct of_device_id davinci_i2c_of_match[] = {
	{.compatible = "ti,davinci-i2c", },
	{.compatible = "ti,keystone-i2c", },
	{},
};
MODULE_DEVICE_TABLE(of, davinci_i2c_of_match);

static int davinci_i2c_probe(struct platform_device *pdev)
{
	struct davinci_i2c_dev *dev;
	struct i2c_adapter *adap;
	struct resource *mem;
	int r, irq;

	irq = platform_get_irq(pdev, 0);
	if (irq <= 0) {
		if (!irq)
			irq = -ENXIO;
		if (irq != -EPROBE_DEFER)
			dev_err(&pdev->dev,
				"can't get irq resource ret=%d\n", irq);
		return irq;
	}

	dev = devm_kzalloc(&pdev->dev, sizeof(struct davinci_i2c_dev),
			GFP_KERNEL);
	if (!dev) {
		dev_err(&pdev->dev, "Memory allocation failed\n");
		return -ENOMEM;
	}

	init_completion(&dev->cmd_complete);
#ifdef CONFIG_CPU_FREQ
	init_completion(&dev->xfr_complete);
#endif
	dev->dev = &pdev->dev;
	dev->irq = irq;
	dev->pdata = dev_get_platdata(&pdev->dev);
	platform_set_drvdata(pdev, dev);

	if (!dev->pdata && pdev->dev.of_node) {
		u32 prop;

		dev->pdata = devm_kzalloc(&pdev->dev,
			sizeof(struct davinci_i2c_platform_data), GFP_KERNEL);
		if (!dev->pdata)
			return -ENOMEM;

		memcpy(dev->pdata, &davinci_i2c_platform_data_default,
			sizeof(struct davinci_i2c_platform_data));
		if (!of_property_read_u32(pdev->dev.of_node, "clock-frequency",
			&prop))
			dev->pdata->bus_freq = prop / 1000;

		dev->pdata->has_pfunc =
			of_property_read_bool(pdev->dev.of_node,
					      "ti,has-pfunc");
	} else if (!dev->pdata) {
		dev->pdata = &davinci_i2c_platform_data_default;
	}

	dev->clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(dev->clk))
		return -ENODEV;
	clk_prepare_enable(dev->clk);

	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	dev->base = devm_ioremap_resource(&pdev->dev, mem);
	if (IS_ERR(dev->base)) {
		r = PTR_ERR(dev->base);
		goto err_unuse_clocks;
	}

	i2c_davinci_init(dev);

	r = devm_request_irq(&pdev->dev, dev->irq, i2c_davinci_isr, 0,
			pdev->name, dev);
	if (r) {
		dev_err(&pdev->dev, "failure requesting irq %i\n", dev->irq);
		goto err_unuse_clocks;
	}

	r = i2c_davinci_cpufreq_register(dev);
	if (r) {
		dev_err(&pdev->dev, "failed to register cpufreq\n");
		goto err_unuse_clocks;
	}

	adap = &dev->adapter;
	i2c_set_adapdata(adap, dev);
	adap->owner = THIS_MODULE;
	adap->class = I2C_CLASS_DEPRECATED;
	strlcpy(adap->name, "DaVinci I2C adapter", sizeof(adap->name));
	adap->algo = &i2c_davinci_algo;
	adap->dev.parent = &pdev->dev;
	adap->timeout = DAVINCI_I2C_TIMEOUT;
	adap->dev.of_node = pdev->dev.of_node;

	if (dev->pdata->has_pfunc)
		adap->bus_recovery_info = &davinci_i2c_scl_recovery_info;
	else if (dev->pdata->scl_pin) {
		adap->bus_recovery_info = &davinci_i2c_gpio_recovery_info;
		adap->bus_recovery_info->scl_gpio = dev->pdata->scl_pin;
		adap->bus_recovery_info->sda_gpio = dev->pdata->sda_pin;
	}

	adap->nr = pdev->id;
	r = i2c_add_numbered_adapter(adap);
	if (r) {
		dev_err(&pdev->dev, "failure adding adapter\n");
		goto err_unuse_clocks;
	}

	return 0;

err_unuse_clocks:
	clk_disable_unprepare(dev->clk);
	dev->clk = NULL;
	return r;
}

static int davinci_i2c_remove(struct platform_device *pdev)
{
	struct davinci_i2c_dev *dev = platform_get_drvdata(pdev);

	i2c_davinci_cpufreq_deregister(dev);

	i2c_del_adapter(&dev->adapter);

	clk_disable_unprepare(dev->clk);
	dev->clk = NULL;

	davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, 0);

	return 0;
}

#ifdef CONFIG_PM
static int davinci_i2c_suspend(struct device *dev)
{
	struct platform_device *pdev = to_platform_device(dev);
	struct davinci_i2c_dev *i2c_dev = platform_get_drvdata(pdev);

	/* put I2C into reset */
	davinci_i2c_reset_ctrl(i2c_dev, 0);
	clk_disable_unprepare(i2c_dev->clk);

	return 0;
}

static int davinci_i2c_resume(struct device *dev)
{
	struct platform_device *pdev = to_platform_device(dev);
	struct davinci_i2c_dev *i2c_dev = platform_get_drvdata(pdev);

	clk_prepare_enable(i2c_dev->clk);
	/* take I2C out of reset */
	davinci_i2c_reset_ctrl(i2c_dev, 1);

	return 0;
}

static const struct dev_pm_ops davinci_i2c_pm = {
	.suspend        = davinci_i2c_suspend,
	.resume         = davinci_i2c_resume,
};

#define davinci_i2c_pm_ops (&davinci_i2c_pm)
#else
#define davinci_i2c_pm_ops NULL
#endif

/* work with hotplug and coldplug */
MODULE_ALIAS("platform:i2c_davinci");

static struct platform_driver davinci_i2c_driver = {
	.probe		= davinci_i2c_probe,
	.remove		= davinci_i2c_remove,
	.driver		= {
		.name	= "i2c_davinci",
		.pm	= davinci_i2c_pm_ops,
		.of_match_table = davinci_i2c_of_match,
	},
};

/* I2C may be needed to bring up other drivers */
static int __init davinci_i2c_init_driver(void)
{
	return platform_driver_register(&davinci_i2c_driver);
}
subsys_initcall(davinci_i2c_init_driver);

static void __exit davinci_i2c_exit_driver(void)
{
	platform_driver_unregister(&davinci_i2c_driver);
}
module_exit(davinci_i2c_exit_driver);

MODULE_AUTHOR("Texas Instruments India");
MODULE_DESCRIPTION("TI DaVinci I2C bus adapter");
MODULE_LICENSE("GPL");