/*
 * 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/consumer.h>
#include <linux/of_device.h>
#include <linux/platform_data/i2c-davinci.h>
#include <linux/pm_runtime.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)

/* timeout for pm runtime autosuspend */
#define DAVINCI_I2C_PM_TIMEOUT  1000    /* ms */

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 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
         */

        /*
         * Both Davinci and current Keystone User Guides recommend a value
         * between 7MHz and 12MHz. In reality 7MHz module clock doesn't
         * always produce enough margin between SDA and SCL transitions.
         * Measurements show that the higher the module clock is, the
         * bigger is the margin, providing more reliable communication.
         * So we better target for 12MHz.
         */
        psc = (input_clock / 12000000) - 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.
         *
         * Note:
         * CLKH is not allowed to be 0, in this case I2C clock is not generated
         * at all
         */
        if (clk > clkl + d) {
                clkh = clk - clkl - d;
                clkl -= d;
        } else {
                clkh = 1;
                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_scl_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_scl_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=%zu\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 = pm_runtime_get_sync(dev->dev);
        if (ret < 0) {
                dev_err(dev->dev, "Failed to runtime_get device: %d\n", ret);
                pm_runtime_put_noidle(dev->dev);
                return ret;
        }

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

        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)
                        goto out;
        }

        ret = num;

out:
        pm_runtime_mark_last_busy(dev->dev);
        pm_runtime_put_autosuspend(dev->dev);

        return ret;
}

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;

        if (pm_runtime_suspended(dev->dev))
                return IRQ_NONE;

        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);

        i2c_lock_adapter(&dev->adapter);
        if (val == CPUFREQ_PRECHANGE) {
                davinci_i2c_reset_ctrl(dev, 0);
        } else if (val == CPUFREQ_POSTCHANGE) {
                i2c_davinci_calc_clk_dividers(dev);
                davinci_i2c_reset_ctrl(dev, 1);
        }
        i2c_unlock_adapter(&dev->adapter);

        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 const 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;
        struct i2c_bus_recovery_info *rinfo;
        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);

        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 PTR_ERR(dev->clk);

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

        pm_runtime_set_autosuspend_delay(dev->dev,
                                         DAVINCI_I2C_PM_TIMEOUT);
        pm_runtime_use_autosuspend(dev->dev);

        pm_runtime_enable(dev->dev);

        r = pm_runtime_get_sync(dev->dev);
        if (r < 0) {
                dev_err(dev->dev, "failed to runtime_get device: %d\n", r);
                pm_runtime_put_noidle(dev->dev);
                return r;
        }

        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->gpio_recovery) {
                rinfo =  &davinci_i2c_gpio_recovery_info;
                adap->bus_recovery_info = rinfo;
                rinfo->scl_gpiod = devm_gpiod_get(&pdev->dev, "scl",
                                                  GPIOD_OUT_HIGH_OPEN_DRAIN);
                if (IS_ERR(rinfo->scl_gpiod)) {
                        r = PTR_ERR(rinfo->scl_gpiod);
                        goto err_unuse_clocks;
                }
                rinfo->sda_gpiod = devm_gpiod_get(&pdev->dev, "sda", GPIOD_IN);
                if (IS_ERR(rinfo->sda_gpiod)) {
                        r = PTR_ERR(rinfo->sda_gpiod);
                        goto err_unuse_clocks;
                }
        }

        adap->nr = pdev->id;
        r = i2c_add_numbered_adapter(adap);
        if (r)
                goto err_unuse_clocks;

        pm_runtime_mark_last_busy(dev->dev);
        pm_runtime_put_autosuspend(dev->dev);

        return 0;

err_unuse_clocks:
        pm_runtime_dont_use_autosuspend(dev->dev);
        pm_runtime_put_sync(dev->dev);
        pm_runtime_disable(dev->dev);

        return r;
}

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

        i2c_davinci_cpufreq_deregister(dev);

        i2c_del_adapter(&dev->adapter);

        ret = pm_runtime_get_sync(&pdev->dev);
        if (ret < 0) {
                pm_runtime_put_noidle(&pdev->dev);
                return ret;
        }

        davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, 0);

        pm_runtime_dont_use_autosuspend(dev->dev);
        pm_runtime_put_sync(dev->dev);
        pm_runtime_disable(dev->dev);

        return 0;
}

#ifdef CONFIG_PM
static int davinci_i2c_suspend(struct device *dev)
{
        struct davinci_i2c_dev *i2c_dev = dev_get_drvdata(dev);

        /* put I2C into reset */
        davinci_i2c_reset_ctrl(i2c_dev, 0);

        return 0;
}

static int davinci_i2c_resume(struct device *dev)
{
        struct davinci_i2c_dev *i2c_dev = dev_get_drvdata(dev);

        /* 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,
        SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
                                      pm_runtime_force_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");