/*
 * Support for Moorestown/Medfield I2C chip
 *
 * Copyright (c) 2009 Intel Corporation.
 * Copyright (c) 2009 Synopsys. Inc.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License, version
 * 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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., 51
 * Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 *
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/pci.h>
#include <linux/interrupt.h>
#include <linux/pm_runtime.h>
#include <linux/io.h>

#define DRIVER_NAME     "i2c-intel-mid"
#define VERSION         "Version 0.5ac2"
#define PLATFORM        "Moorestown/Medfield"

/* Tables use: 0 Moorestown, 1 Medfield */
#define NUM_PLATFORMS   2
enum platform_enum {
        MOORESTOWN = 0,
        MEDFIELD = 1,
};

enum mid_i2c_status {
        STATUS_IDLE = 0,
        STATUS_READ_START,
        STATUS_READ_IN_PROGRESS,
        STATUS_READ_SUCCESS,
        STATUS_WRITE_START,
        STATUS_WRITE_SUCCESS,
        STATUS_XFER_ABORT,
        STATUS_STANDBY
};

/**
 * struct intel_mid_i2c_private - per device I²C context
 * @adap: core i2c layer adapter information
 * @dev: device reference for power management
 * @base: register base
 * @speed: speed mode for this port
 * @complete: completion object for transaction wait
 * @abort: reason for last abort
 * @rx_buf: pointer into working receive buffer
 * @rx_buf_len: receive buffer length
 * @status: adapter state machine
 * @msg: the message we are currently processing
 * @platform: the MID device type we are part of
 * @lock: transaction serialization
 *
 * We allocate one of these per device we discover, it holds the core
 * i2c layer objects and the data we need to track privately.
 */
struct intel_mid_i2c_private {
        struct i2c_adapter adap;
        struct device *dev;
        void __iomem *base;
        int speed;
        struct completion complete;
        int abort;
        u8 *rx_buf;
        int rx_buf_len;
        enum mid_i2c_status status;
        struct i2c_msg *msg;
        enum platform_enum platform;
        struct mutex lock;
};

#define NUM_SPEEDS              3

#define ACTIVE                  0
#define STANDBY                 1


/* Control register */
#define IC_CON                  0x00
#define SLV_DIS                 (1 << 6)        /* Disable slave mode */
#define RESTART                 (1 << 5)        /* Send a Restart condition */
#define ADDR_10BIT              (1 << 4)        /* 10-bit addressing */
#define STANDARD_MODE           (1 << 1)        /* standard mode */
#define FAST_MODE               (2 << 1)        /* fast mode */
#define HIGH_MODE               (3 << 1)        /* high speed mode */
#define MASTER_EN               (1 << 0)        /* Master mode */

/* Target address register */
#define IC_TAR                  0x04
#define IC_TAR_10BIT_ADDR       (1 << 12)       /* 10-bit addressing */
#define IC_TAR_SPECIAL          (1 << 11)       /* Perform special I2C cmd */
#define IC_TAR_GC_OR_START      (1 << 10)       /* 0: Gerneral Call Address */
                                                /* 1: START BYTE */
/* Slave Address Register */
#define IC_SAR                  0x08            /* Not used in Master mode */

/* High Speed Master Mode Code Address Register */
#define IC_HS_MADDR             0x0c

/* Rx/Tx Data Buffer and Command Register */
#define IC_DATA_CMD             0x10
#define IC_RD                   (1 << 8)        /* 1: Read 0: Write */

/* Standard Speed Clock SCL High Count Register */
#define IC_SS_SCL_HCNT          0x14

/* Standard Speed Clock SCL Low Count Register */
#define IC_SS_SCL_LCNT          0x18

/* Fast Speed Clock SCL High Count Register */
#define IC_FS_SCL_HCNT          0x1c

/* Fast Spedd Clock SCL Low Count Register */
#define IC_FS_SCL_LCNT          0x20

/* High Speed Clock SCL High Count Register */
#define IC_HS_SCL_HCNT          0x24

/* High Speed Clock SCL Low Count Register */
#define IC_HS_SCL_LCNT          0x28

/* Interrupt Status Register */
#define IC_INTR_STAT            0x2c            /* Read only */
#define R_GEN_CALL              (1 << 11)
#define R_START_DET             (1 << 10)
#define R_STOP_DET              (1 << 9)
#define R_ACTIVITY              (1 << 8)
#define R_RX_DONE               (1 << 7)
#define R_TX_ABRT               (1 << 6)
#define R_RD_REQ                (1 << 5)
#define R_TX_EMPTY              (1 << 4)
#define R_TX_OVER               (1 << 3)
#define R_RX_FULL               (1 << 2)
#define R_RX_OVER               (1 << 1)
#define R_RX_UNDER              (1 << 0)

/* Interrupt Mask Register */
#define IC_INTR_MASK            0x30            /* Read and Write */
#define M_GEN_CALL              (1 << 11)
#define M_START_DET             (1 << 10)
#define M_STOP_DET              (1 << 9)
#define M_ACTIVITY              (1 << 8)
#define M_RX_DONE               (1 << 7)
#define M_TX_ABRT               (1 << 6)
#define M_RD_REQ                (1 << 5)
#define M_TX_EMPTY              (1 << 4)
#define M_TX_OVER               (1 << 3)
#define M_RX_FULL               (1 << 2)
#define M_RX_OVER               (1 << 1)
#define M_RX_UNDER              (1 << 0)

/* Raw Interrupt Status Register */
#define IC_RAW_INTR_STAT        0x34            /* Read Only */
#define GEN_CALL                (1 << 11)       /* General call */
#define START_DET               (1 << 10)       /* (RE)START occurred */
#define STOP_DET                (1 << 9)        /* STOP occurred */
#define ACTIVITY                (1 << 8)        /* Bus busy */
#define RX_DONE                 (1 << 7)        /* Not used in Master mode */
#define TX_ABRT                 (1 << 6)        /* Transmit Abort */
#define RD_REQ                  (1 << 5)        /* Not used in Master mode */
#define TX_EMPTY                (1 << 4)        /* TX FIFO <= threshold */
#define TX_OVER                 (1 << 3)        /* TX FIFO overflow */
#define RX_FULL                 (1 << 2)        /* RX FIFO >= threshold */
#define RX_OVER                 (1 << 1)        /* RX FIFO overflow */
#define RX_UNDER                (1 << 0)        /* RX FIFO empty */

/* Receive FIFO Threshold Register */
#define IC_RX_TL                0x38

/* Transmit FIFO Treshold Register */
#define IC_TX_TL                0x3c

/* Clear Combined and Individual Interrupt Register */
#define IC_CLR_INTR             0x40
#define CLR_INTR                (1 << 0)

/* Clear RX_UNDER Interrupt Register */
#define IC_CLR_RX_UNDER         0x44
#define CLR_RX_UNDER            (1 << 0)

/* Clear RX_OVER Interrupt Register */
#define IC_CLR_RX_OVER          0x48
#define CLR_RX_OVER             (1 << 0)

/* Clear TX_OVER Interrupt Register */
#define IC_CLR_TX_OVER          0x4c
#define CLR_TX_OVER             (1 << 0)

#define IC_CLR_RD_REQ           0x50

/* Clear TX_ABRT Interrupt Register */
#define IC_CLR_TX_ABRT          0x54
#define CLR_TX_ABRT             (1 << 0)
#define IC_CLR_RX_DONE          0x58

/* Clear ACTIVITY Interrupt Register */
#define IC_CLR_ACTIVITY         0x5c
#define CLR_ACTIVITY            (1 << 0)

/* Clear STOP_DET Interrupt Register */
#define IC_CLR_STOP_DET         0x60
#define CLR_STOP_DET            (1 << 0)

/* Clear START_DET Interrupt Register */
#define IC_CLR_START_DET        0x64
#define CLR_START_DET           (1 << 0)

/* Clear GEN_CALL Interrupt Register */
#define IC_CLR_GEN_CALL         0x68
#define CLR_GEN_CALL            (1 << 0)

/* Enable Register */
#define IC_ENABLE               0x6c
#define ENABLE                  (1 << 0)

/* Status Register */
#define IC_STATUS               0x70            /* Read Only */
#define STAT_SLV_ACTIVITY       (1 << 6)        /* Slave not in idle */
#define STAT_MST_ACTIVITY       (1 << 5)        /* Master not in idle */
#define STAT_RFF                (1 << 4)        /* RX FIFO Full */
#define STAT_RFNE               (1 << 3)        /* RX FIFO Not Empty */
#define STAT_TFE                (1 << 2)        /* TX FIFO Empty */
#define STAT_TFNF               (1 << 1)        /* TX FIFO Not Full */
#define STAT_ACTIVITY           (1 << 0)        /* Activity Status */

/* Transmit FIFO Level Register */
#define IC_TXFLR                0x74            /* Read Only */
#define TXFLR                   (1 << 0)        /* TX FIFO level */

/* Receive FIFO Level Register */
#define IC_RXFLR                0x78            /* Read Only */
#define RXFLR                   (1 << 0)        /* RX FIFO level */

/* Transmit Abort Source Register */
#define IC_TX_ABRT_SOURCE       0x80
#define ABRT_SLVRD_INTX         (1 << 15)
#define ABRT_SLV_ARBLOST        (1 << 14)
#define ABRT_SLVFLUSH_TXFIFO    (1 << 13)
#define ARB_LOST                (1 << 12)
#define ABRT_MASTER_DIS         (1 << 11)
#define ABRT_10B_RD_NORSTRT     (1 << 10)
#define ABRT_SBYTE_NORSTRT      (1 << 9)
#define ABRT_HS_NORSTRT         (1 << 8)
#define ABRT_SBYTE_ACKDET       (1 << 7)
#define ABRT_HS_ACKDET          (1 << 6)
#define ABRT_GCALL_READ         (1 << 5)
#define ABRT_GCALL_NOACK        (1 << 4)
#define ABRT_TXDATA_NOACK       (1 << 3)
#define ABRT_10ADDR2_NOACK      (1 << 2)
#define ABRT_10ADDR1_NOACK      (1 << 1)
#define ABRT_7B_ADDR_NOACK      (1 << 0)

/* Enable Status Register */
#define IC_ENABLE_STATUS        0x9c
#define IC_EN                   (1 << 0)        /* I2C in an enabled state */

/* Component Parameter Register 1*/
#define IC_COMP_PARAM_1         0xf4
#define APB_DATA_WIDTH          (0x3 << 0)

/* added by xiaolin --begin */
#define SS_MIN_SCL_HIGH         4000
#define SS_MIN_SCL_LOW          4700
#define FS_MIN_SCL_HIGH         600
#define FS_MIN_SCL_LOW          1300
#define HS_MIN_SCL_HIGH_100PF   60
#define HS_MIN_SCL_LOW_100PF    120

#define STANDARD                0
#define FAST                    1
#define HIGH                    2

#define NUM_SPEEDS              3

static int speed_mode[6] = {
        FAST,
        FAST,
        FAST,
        STANDARD,
        FAST,
        FAST
};

static int ctl_num = 6;
module_param_array(speed_mode, int, &ctl_num, S_IRUGO);
MODULE_PARM_DESC(speed_mode, "Set the speed of the i2c interface (0-2)");

/**
 * intel_mid_i2c_disable - Disable I2C controller
 * @adap: struct pointer to i2c_adapter
 *
 * Return Value:
 * 0            success
 * -EBUSY       if device is busy
 * -ETIMEDOUT   if i2c cannot be disabled within the given time
 *
 * I2C bus state should be checked prior to disabling the hardware. If bus is
 * not in idle state, an errno is returned. Write "0" to IC_ENABLE to disable
 * I2C controller.
 */
static int intel_mid_i2c_disable(struct i2c_adapter *adap)
{
        struct intel_mid_i2c_private *i2c = i2c_get_adapdata(adap);
        int err = 0;
        int count = 0;
        int ret1, ret2;
        static const u16 delay[NUM_SPEEDS] = {100, 25, 3};

        /* Set IC_ENABLE to 0 */
        writel(0, i2c->base + IC_ENABLE);

        /* Check if device is busy */
        dev_dbg(&adap->dev, "mrst i2c disable\n");
        while ((ret1 = readl(i2c->base + IC_ENABLE_STATUS) & 0x1)
                || (ret2 = readl(i2c->base + IC_STATUS) & 0x1)) {
                udelay(delay[i2c->speed]);
                writel(0, i2c->base + IC_ENABLE);
                dev_dbg(&adap->dev, "i2c is busy, count is %d speed %d\n",
                        count, i2c->speed);
                if (count++ > 10) {
                        err = -ETIMEDOUT;
                        break;
                }
        }

        /* Clear all interrupts */
        readl(i2c->base + IC_CLR_INTR);
        readl(i2c->base + IC_CLR_STOP_DET);
        readl(i2c->base + IC_CLR_START_DET);
        readl(i2c->base + IC_CLR_ACTIVITY);
        readl(i2c->base + IC_CLR_TX_ABRT);
        readl(i2c->base + IC_CLR_RX_OVER);
        readl(i2c->base + IC_CLR_RX_UNDER);
        readl(i2c->base + IC_CLR_TX_OVER);
        readl(i2c->base + IC_CLR_RX_DONE);
        readl(i2c->base + IC_CLR_GEN_CALL);

        /* Disable all interupts */
        writel(0x0000, i2c->base + IC_INTR_MASK);

        return err;
}

/**
 * intel_mid_i2c_hwinit - Initialize the I2C hardware registers
 * @dev: pci device struct pointer
 *
 * This function will be called in intel_mid_i2c_probe() before device
 * registration.
 *
 * Return Values:
 * 0            success
 * -EBUSY       i2c cannot be disabled
 * -ETIMEDOUT   i2c cannot be disabled
 * -EFAULT      If APB data width is not 32-bit wide
 *
 * I2C should be disabled prior to other register operation. If failed, an
 * errno is returned. Mask and Clear all interrpts, this should be done at
 * first.  Set common registers which will not be modified during normal
 * transfers, including: control register, FIFO threshold and clock freq.
 * Check APB data width at last.
 */
static int intel_mid_i2c_hwinit(struct intel_mid_i2c_private *i2c)
{
        int err;

        static const u16 hcnt[NUM_PLATFORMS][NUM_SPEEDS] = {
                { 0x75,  0x15, 0x07 },
                { 0x04c,  0x10, 0x06 }
        };
        static const u16 lcnt[NUM_PLATFORMS][NUM_SPEEDS] = {
                { 0x7C,  0x21, 0x0E },
                { 0x053, 0x19, 0x0F }
        };

        /* Disable i2c first */
        err = intel_mid_i2c_disable(&i2c->adap);
        if (err)
                return err;

        /*
         * Setup clock frequency and speed mode
         * Enable restart condition,
         * enable master FSM, disable slave FSM,
         * use target address when initiating transfer
         */

        writel((i2c->speed + 1) << 1 | SLV_DIS | RESTART | MASTER_EN,
                i2c->base + IC_CON);
        writel(hcnt[i2c->platform][i2c->speed],
                i2c->base + (IC_SS_SCL_HCNT + (i2c->speed << 3)));
        writel(lcnt[i2c->platform][i2c->speed],
                i2c->base + (IC_SS_SCL_LCNT + (i2c->speed << 3)));

        /* Set tranmit & receive FIFO threshold to zero */
        writel(0x0, i2c->base + IC_RX_TL);
        writel(0x0, i2c->base + IC_TX_TL);

        return 0;
}

/**
 * intel_mid_i2c_func - Return the supported three I2C operations.
 * @adapter: i2c_adapter struct pointer
 */
static u32 intel_mid_i2c_func(struct i2c_adapter *adapter)
{
        return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR | I2C_FUNC_SMBUS_EMUL;
}

/**
 * intel_mid_i2c_address_neq - To check if the addresses for different i2c messages
 * are equal.
 * @p1: first i2c_msg
 * @p2: second i2c_msg
 *
 * Return Values:
 * 0     if addresses are equal
 * 1     if not equal
 *
 * Within a single transfer, the I2C client may need to send its address more
 * than once. So a check if the addresses match is needed.
 */
static inline bool intel_mid_i2c_address_neq(const struct i2c_msg *p1,
                                       const struct i2c_msg *p2)
{
        if (p1->addr != p2->addr)
                return 1;
        if ((p1->flags ^ p2->flags) & I2C_M_TEN)
                return 1;
        return 0;
}

/**
 * intel_mid_i2c_abort - To handle transfer abortions and print error messages.
 * @adap: i2c_adapter struct pointer
 *
 * By reading register IC_TX_ABRT_SOURCE, various transfer errors can be
 * distingushed. At present, no circumstances have been found out that
 * multiple errors would be occurred simutaneously, so we simply use the
 * register value directly.
 *
 * At last the error bits are cleared. (Note clear ABRT_SBYTE_NORSTRT bit need
 * a few extra steps)
 */
static void intel_mid_i2c_abort(struct intel_mid_i2c_private *i2c)
{
        /* Read about source register */
        int abort = i2c->abort;
        struct i2c_adapter *adap = &i2c->adap;

        /* Single transfer error check:
         * According to databook, TX/RX FIFOs would be flushed when
         * the abort interrupt occurred.
         */
        if (abort & ABRT_MASTER_DIS)
                dev_err(&adap->dev,
                "initiate master operation with master mode disabled.\n");
        if (abort & ABRT_10B_RD_NORSTRT)
                dev_err(&adap->dev,
        "RESTART disabled and master sent READ cmd in 10-bit addressing.\n");

        if (abort & ABRT_SBYTE_NORSTRT) {
                dev_err(&adap->dev,
                "RESTART disabled and user is trying to send START byte.\n");
                writel(~ABRT_SBYTE_NORSTRT, i2c->base + IC_TX_ABRT_SOURCE);
                writel(RESTART, i2c->base + IC_CON);
                writel(~IC_TAR_SPECIAL, i2c->base + IC_TAR);
        }

        if (abort & ABRT_SBYTE_ACKDET)
                dev_err(&adap->dev,
                        "START byte was not acknowledged.\n");
        if (abort & ABRT_TXDATA_NOACK)
                dev_dbg(&adap->dev,
                        "No acknowledgement received from slave.\n");
        if (abort & ABRT_10ADDR2_NOACK)
                dev_dbg(&adap->dev,
        "The 2nd address byte of the 10-bit address was not acknowledged.\n");
        if (abort & ABRT_10ADDR1_NOACK)
                dev_dbg(&adap->dev,
        "The 1st address byte of 10-bit address was not acknowledged.\n");
        if (abort & ABRT_7B_ADDR_NOACK)
                dev_dbg(&adap->dev,
                        "I2C slave device not acknowledged.\n");

        /* Clear TX_ABRT bit */
        readl(i2c->base + IC_CLR_TX_ABRT);
        i2c->status = STATUS_XFER_ABORT;
}

/**
 * xfer_read - Internal function to implement master read transfer.
 * @adap: i2c_adapter struct pointer
 * @buf: buffer in i2c_msg
 * @length: number of bytes to be read
 *
 * Return Values:
 * 0            if the read transfer succeeds
 * -ETIMEDOUT   if cannot read the "raw" interrupt register
 * -EINVAL      if a transfer abort occurred
 *
 * For every byte, a "READ" command will be loaded into IC_DATA_CMD prior to
 * data transfer. The actual "read" operation will be performed if an RX_FULL
 * interrupt occurred.
 *
 * Note there may be two interrupt signals captured, one should read
 * IC_RAW_INTR_STAT to separate between errors and actual data.
 */
static int xfer_read(struct i2c_adapter *adap, unsigned char *buf, int length)
{
        struct intel_mid_i2c_private *i2c = i2c_get_adapdata(adap);
        int i = length;
        int err;

        if (length >= 256) {
                dev_err(&adap->dev,
                        "I2C FIFO cannot support larger than 256 bytes\n");
                return -EMSGSIZE;
        }

        INIT_COMPLETION(i2c->complete);

        readl(i2c->base + IC_CLR_INTR);
        writel(0x0044, i2c->base + IC_INTR_MASK);

        i2c->status = STATUS_READ_START;

        while (i--)
                writel(IC_RD, i2c->base + IC_DATA_CMD);

        i2c->status = STATUS_READ_START;
        err = wait_for_completion_interruptible_timeout(&i2c->complete, HZ);
        if (!err) {
                dev_err(&adap->dev, "Timeout for ACK from I2C slave device\n");
                intel_mid_i2c_hwinit(i2c);
                return -ETIMEDOUT;
        }
        if (i2c->status == STATUS_READ_SUCCESS)
                return 0;
        else
                return -EIO;
}

/**
 * xfer_write - Internal function to implement master write transfer.
 * @adap: i2c_adapter struct pointer
 * @buf: buffer in i2c_msg
 * @length: number of bytes to be read
 *
 * Return Values:
 * 0    if the read transfer succeeds
 * -ETIMEDOUT   if we cannot read the "raw" interrupt register
 * -EINVAL      if a transfer abort occurred
 *
 * For every byte, a "WRITE" command will be loaded into IC_DATA_CMD prior to
 * data transfer. The actual "write" operation will be performed when the
 * RX_FULL interrupt signal occurs.
 *
 * Note there may be two interrupt signals captured, one should read
 * IC_RAW_INTR_STAT to separate between errors and actual data.
 */
static int xfer_write(struct i2c_adapter *adap,
                      unsigned char *buf, int length)
{
        struct intel_mid_i2c_private *i2c = i2c_get_adapdata(adap);
        int i, err;

        if (length >= 256) {
                dev_err(&adap->dev,
                        "I2C FIFO cannot support larger than 256 bytes\n");
                return -EMSGSIZE;
        }

        INIT_COMPLETION(i2c->complete);

        readl(i2c->base + IC_CLR_INTR);
        writel(0x0050, i2c->base + IC_INTR_MASK);

        i2c->status = STATUS_WRITE_START;
        for (i = 0; i < length; i++)
                writel((u16)(*(buf + i)), i2c->base + IC_DATA_CMD);

        i2c->status = STATUS_WRITE_START;
        err = wait_for_completion_interruptible_timeout(&i2c->complete, HZ);
        if (!err) {
                dev_err(&adap->dev, "Timeout for ACK from I2C slave device\n");
                intel_mid_i2c_hwinit(i2c);
                return -ETIMEDOUT;
        } else {
                if (i2c->status == STATUS_WRITE_SUCCESS)
                        return 0;
                else
                        return -EIO;
        }
}

static int intel_mid_i2c_setup(struct i2c_adapter *adap,  struct i2c_msg *pmsg)
{
        struct intel_mid_i2c_private *i2c = i2c_get_adapdata(adap);
        int err;
        u32 reg;
        u32 bit_mask;
        u32 mode;

        /* Disable device first */
        err = intel_mid_i2c_disable(adap);
        if (err) {
                dev_err(&adap->dev,
                        "Cannot disable i2c controller, timeout\n");
                return err;
        }

        mode = (1 + i2c->speed) << 1;
        /* set the speed mode */
        reg = readl(i2c->base + IC_CON);
        if ((reg & 0x06) != mode) {
                dev_dbg(&adap->dev, "set mode %d\n", i2c->speed);
                writel((reg & ~0x6) | mode, i2c->base + IC_CON);
        }

        reg = readl(i2c->base + IC_CON);
        /* use 7-bit addressing */
        if (pmsg->flags & I2C_M_TEN) {
                if ((reg & ADDR_10BIT) != ADDR_10BIT) {
                        dev_dbg(&adap->dev, "set i2c 10 bit address mode\n");
                        writel(reg | ADDR_10BIT, i2c->base + IC_CON);
                }
        } else {
                if ((reg & ADDR_10BIT) != 0x0) {
                        dev_dbg(&adap->dev, "set i2c 7 bit address mode\n");
                        writel(reg & ~ADDR_10BIT, i2c->base + IC_CON);
                }
        }
        /* enable restart conditions */
        reg = readl(i2c->base + IC_CON);
        if ((reg & RESTART) != RESTART) {
                dev_dbg(&adap->dev, "enable restart conditions\n");
                writel(reg | RESTART, i2c->base + IC_CON);
        }

        /* enable master FSM */
        reg = readl(i2c->base + IC_CON);
        dev_dbg(&adap->dev, "ic_con reg is 0x%x\n", reg);
        writel(reg | MASTER_EN, i2c->base + IC_CON);
        if ((reg & SLV_DIS) != SLV_DIS) {
                dev_dbg(&adap->dev, "enable master FSM\n");
                writel(reg | SLV_DIS, i2c->base + IC_CON);
                dev_dbg(&adap->dev, "ic_con reg is 0x%x\n", reg);
        }

        /* use target address when initiating transfer */
        reg = readl(i2c->base + IC_TAR);
        bit_mask = IC_TAR_SPECIAL | IC_TAR_GC_OR_START;

        if ((reg & bit_mask) != 0x0) {
                dev_dbg(&adap->dev,
         "WR: use target address when intiating transfer, i2c_tx_target\n");
                writel(reg & ~bit_mask, i2c->base + IC_TAR);
        }

        /* set target address to the I2C slave address */
        dev_dbg(&adap->dev,
                "set target address to the I2C slave address, addr is %x\n",
                        pmsg->addr);
        writel(pmsg->addr | (pmsg->flags & I2C_M_TEN ? IC_TAR_10BIT_ADDR : 0),
                i2c->base + IC_TAR);

        /* Enable I2C controller */
        writel(ENABLE, i2c->base + IC_ENABLE);

        return 0;
}

/**
 * intel_mid_i2c_xfer - Main master transfer routine.
 * @adap: i2c_adapter struct pointer
 * @pmsg: i2c_msg struct pointer
 * @num: number of i2c_msg
 *
 * Return Values:
 * +            number of messages transferred
 * -ETIMEDOUT   If cannot disable I2C controller or read IC_STATUS
 * -EINVAL      If the address in i2c_msg is invalid
 *
 * This function will be registered in i2c-core and exposed to external
 * I2C clients.
 * 1. Disable I2C controller
 * 2. Unmask three interrupts: RX_FULL, TX_EMPTY, TX_ABRT
 * 3. Check if address in i2c_msg is valid
 * 4. Enable I2C controller
 * 5. Perform real transfer (call xfer_read or xfer_write)
 * 6. Wait until the current transfer is finished (check bus state)
 * 7. Mask and clear all interrupts
 */
static int intel_mid_i2c_xfer(struct i2c_adapter *adap,
                         struct i2c_msg *pmsg,
                         int num)
{
        struct intel_mid_i2c_private *i2c = i2c_get_adapdata(adap);
        int i, err = 0;

        /* if number of messages equal 0*/
        if (num == 0)
                return 0;

        pm_runtime_get(i2c->dev);

        mutex_lock(&i2c->lock);
        dev_dbg(&adap->dev, "intel_mid_i2c_xfer, process %d msg(s)\n", num);
        dev_dbg(&adap->dev, "slave address is %x\n", pmsg->addr);


        if (i2c->status != STATUS_IDLE) {
                dev_err(&adap->dev, "Adapter %d in transfer/standby\n",
                                                                adap->nr);
                mutex_unlock(&i2c->lock);
                pm_runtime_put(i2c->dev);
                return -1;
        }


        for (i = 1; i < num; i++) {
                /* Message address equal? */
                if (unlikely(intel_mid_i2c_address_neq(&pmsg[0], &pmsg[i]))) {
                        dev_err(&adap->dev, "Invalid address in msg[%d]\n", i);
                        mutex_unlock(&i2c->lock);
                        pm_runtime_put(i2c->dev);
                        return -EINVAL;
                }
        }

        if (intel_mid_i2c_setup(adap, pmsg)) {
                mutex_unlock(&i2c->lock);
                pm_runtime_put(i2c->dev);
                return -EINVAL;
        }

        for (i = 0; i < num; i++) {
                i2c->msg = pmsg;
                i2c->status = STATUS_IDLE;
                /* Read or Write */
                if (pmsg->flags & I2C_M_RD) {
                        dev_dbg(&adap->dev, "I2C_M_RD\n");
                        err = xfer_read(adap, pmsg->buf, pmsg->len);
                } else {
                        dev_dbg(&adap->dev, "I2C_M_WR\n");
                        err = xfer_write(adap, pmsg->buf, pmsg->len);
                }
                if (err < 0)
                        break;
                dev_dbg(&adap->dev, "msg[%d] transfer complete\n", i);
                pmsg++;         /* next message */
        }

        /* Mask interrupts */
        writel(0x0000, i2c->base + IC_INTR_MASK);
        /* Clear all interrupts */
        readl(i2c->base + IC_CLR_INTR);

        i2c->status = STATUS_IDLE;
        mutex_unlock(&i2c->lock);
        pm_runtime_put(i2c->dev);

        return err;
}

static int intel_mid_i2c_runtime_suspend(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        struct intel_mid_i2c_private *i2c = pci_get_drvdata(pdev);
        struct i2c_adapter *adap = to_i2c_adapter(dev);
        int err;

        if (i2c->status != STATUS_IDLE)
                return -1;

        intel_mid_i2c_disable(adap);

        err = pci_save_state(pdev);
        if (err) {
                dev_err(dev, "pci_save_state failed\n");
                return err;
        }

        err = pci_set_power_state(pdev, PCI_D3hot);
        if (err) {
                dev_err(dev, "pci_set_power_state failed\n");
                return err;
        }
        i2c->status = STATUS_STANDBY;

        return 0;
}

static int intel_mid_i2c_runtime_resume(struct device *dev)
{
        struct pci_dev *pdev = to_pci_dev(dev);
        struct intel_mid_i2c_private *i2c = pci_get_drvdata(pdev);
        int err;

        if (i2c->status != STATUS_STANDBY)
                return 0;

        pci_set_power_state(pdev, PCI_D0);
        pci_restore_state(pdev);
        err = pci_enable_device(pdev);
        if (err) {
                dev_err(dev, "pci_enable_device failed\n");
                return err;
        }

        i2c->status = STATUS_IDLE;

        intel_mid_i2c_hwinit(i2c);
        return err;
}

static void i2c_isr_read(struct intel_mid_i2c_private *i2c)
{
        struct i2c_msg *msg = i2c->msg;
        int rx_num;
        u32 len;
        u8 *buf;

        if (!(msg->flags & I2C_M_RD))
                return;

        if (i2c->status != STATUS_READ_IN_PROGRESS) {
                len = msg->len;
                buf = msg->buf;
        } else {
                len = i2c->rx_buf_len;
                buf = i2c->rx_buf;
        }

        rx_num = readl(i2c->base + IC_RXFLR);

        for (; len > 0 && rx_num > 0; len--, rx_num--)
                *buf++ = readl(i2c->base + IC_DATA_CMD);

        if (len > 0) {
                i2c->status = STATUS_READ_IN_PROGRESS;
                i2c->rx_buf_len = len;
                i2c->rx_buf = buf;
        } else
                i2c->status = STATUS_READ_SUCCESS;

        return;
}

static irqreturn_t intel_mid_i2c_isr(int this_irq, void *dev)
{
        struct intel_mid_i2c_private *i2c = dev;
        u32 stat = readl(i2c->base + IC_INTR_STAT);

        if (!stat)
                return IRQ_NONE;

        dev_dbg(&i2c->adap.dev, "%s, stat = 0x%x\n", __func__, stat);
        stat &= 0x54;

        if (i2c->status != STATUS_WRITE_START &&
            i2c->status != STATUS_READ_START &&
            i2c->status != STATUS_READ_IN_PROGRESS)
                goto err;

        if (stat & TX_ABRT)
                i2c->abort = readl(i2c->base + IC_TX_ABRT_SOURCE);

        readl(i2c->base + IC_CLR_INTR);

        if (stat & TX_ABRT) {
                intel_mid_i2c_abort(i2c);
                goto exit;
        }

        if (stat & RX_FULL) {
                i2c_isr_read(i2c);
                goto exit;
        }

        if (stat & TX_EMPTY) {
                if (readl(i2c->base + IC_STATUS) & 0x4)
                        i2c->status = STATUS_WRITE_SUCCESS;
        }

exit:
        if (i2c->status == STATUS_READ_SUCCESS ||
            i2c->status == STATUS_WRITE_SUCCESS ||
            i2c->status == STATUS_XFER_ABORT) {
                /* Clear all interrupts */
                readl(i2c->base + IC_CLR_INTR);
                /* Mask interrupts */
                writel(0, i2c->base + IC_INTR_MASK);
                complete(&i2c->complete);
        }
err:
        return IRQ_HANDLED;
}

static struct i2c_algorithm intel_mid_i2c_algorithm = {
        .master_xfer    = intel_mid_i2c_xfer,
        .functionality  = intel_mid_i2c_func,
};


static const struct dev_pm_ops intel_mid_i2c_pm_ops = {
        .runtime_suspend = intel_mid_i2c_runtime_suspend,
        .runtime_resume = intel_mid_i2c_runtime_resume,
};

/**
 * intel_mid_i2c_probe - I2C controller initialization routine
 * @dev: pci device
 * @id: device id
 *
 * Return Values:
 * 0            success
 * -ENODEV      If cannot allocate pci resource
 * -ENOMEM      If the register base remapping failed, or
 *              if kzalloc failed
 *
 * Initialization steps:
 * 1. Request for PCI resource
 * 2. Remap the start address of PCI resource to register base
 * 3. Request for device memory region
 * 4. Fill in the struct members of intel_mid_i2c_private
 * 5. Call intel_mid_i2c_hwinit() for hardware initialization
 * 6. Register I2C adapter in i2c-core
 */
static int intel_mid_i2c_probe(struct pci_dev *dev,
                                    const struct pci_device_id *id)
{
        struct intel_mid_i2c_private *mrst;
        unsigned long start, len;
        int err, busnum;
        void __iomem *base = NULL;

        dev_dbg(&dev->dev, "Get into probe function for I2C\n");
        err = pci_enable_device(dev);
        if (err) {
                dev_err(&dev->dev, "Failed to enable I2C PCI device (%d)\n",
                        err);
                goto exit;
        }

        /* Determine the address of the I2C area */
        start = pci_resource_start(dev, 0);
        len = pci_resource_len(dev, 0);
        if (!start || len == 0) {
                dev_err(&dev->dev, "base address not set\n");
                err = -ENODEV;
                goto exit;
        }
        dev_dbg(&dev->dev, "%s i2c resource start 0x%lx, len=%ld\n",
                PLATFORM, start, len);

        err = pci_request_region(dev, 0, DRIVER_NAME);
        if (err) {
                dev_err(&dev->dev, "failed to request I2C region "
                        "0x%lx-0x%lx\n", start,
                        (unsigned long)pci_resource_end(dev, 0));
                goto exit;
        }

        base = ioremap_nocache(start, len);
        if (!base) {
                dev_err(&dev->dev, "I/O memory remapping failed\n");
                err = -ENOMEM;
                goto fail0;
        }

        /* Allocate the per-device data structure, intel_mid_i2c_private */
        mrst = kzalloc(sizeof(struct intel_mid_i2c_private), GFP_KERNEL);
        if (mrst == NULL) {
                dev_err(&dev->dev, "can't allocate interface\n");
                err = -ENOMEM;
                goto fail1;
        }

        /* Initialize struct members */

        snprintf(mrst->adap.name, sizeof(mrst->adap.name),
                "Intel MID I2C at %lx", start);
        mrst->adap.owner = THIS_MODULE;
        mrst->adap.algo = &intel_mid_i2c_algorithm;
        mrst->adap.dev.parent = &dev->dev;
        mrst->dev = &dev->dev;
        mrst->base = base;
        mrst->speed = STANDARD;
        mrst->abort = 0;
        mrst->rx_buf_len = 0;
        mrst->status = STATUS_IDLE;

        pci_set_drvdata(dev, mrst);
        i2c_set_adapdata(&mrst->adap, mrst);

        mrst->adap.nr = busnum = id->driver_data;
        if (dev->device <= 0x0804)
                mrst->platform = MOORESTOWN;
        else
                mrst->platform = MEDFIELD;

        dev_dbg(&dev->dev, "I2C%d\n", busnum);

        if (ctl_num > busnum) {
                if (speed_mode[busnum] < 0 || speed_mode[busnum] >= NUM_SPEEDS)
                        dev_warn(&dev->dev, "invalid speed %d ignored.\n",
                                                        speed_mode[busnum]);
                else
                        mrst->speed = speed_mode[busnum];
        }

        /* Initialize i2c controller */
        err = intel_mid_i2c_hwinit(mrst);
        if (err < 0) {
                dev_err(&dev->dev, "I2C interface initialization failed\n");
                goto fail2;
        }

        mutex_init(&mrst->lock);
        init_completion(&mrst->complete);

        /* Clear all interrupts */
        readl(mrst->base + IC_CLR_INTR);
        writel(0x0000, mrst->base + IC_INTR_MASK);

        err = request_irq(dev->irq, intel_mid_i2c_isr, IRQF_SHARED,
                                        mrst->adap.name, mrst);
        if (err) {
                dev_err(&dev->dev, "Failed to request IRQ for I2C controller: "
                        "%s", mrst->adap.name);
                goto fail2;
        }

        /* Adapter registration */
        err = i2c_add_numbered_adapter(&mrst->adap);
        if (err) {
                dev_err(&dev->dev, "Adapter %s registration failed\n",
                        mrst->adap.name);
                goto fail3;
        }

        dev_dbg(&dev->dev, "%s I2C bus %d driver bind success.\n",
                (mrst->platform == MOORESTOWN) ? "Moorestown" : "Medfield",
                busnum);

        pm_runtime_enable(&dev->dev);
        return 0;

fail3:
        free_irq(dev->irq, mrst);
fail2:
        kfree(mrst);
fail1:
        iounmap(base);
fail0:
        pci_release_region(dev, 0);
exit:
        return err;
}

static void intel_mid_i2c_remove(struct pci_dev *dev)
{
        struct intel_mid_i2c_private *mrst = pci_get_drvdata(dev);
        intel_mid_i2c_disable(&mrst->adap);
        i2c_del_adapter(&mrst->adap);

        free_irq(dev->irq, mrst);
        iounmap(mrst->base);
        kfree(mrst);
        pci_release_region(dev, 0);
}

static const struct pci_device_id intel_mid_i2c_ids[] = {
        /* Moorestown */
        { PCI_VDEVICE(INTEL, 0x0802), 0 },
        { PCI_VDEVICE(INTEL, 0x0803), 1 },
        { PCI_VDEVICE(INTEL, 0x0804), 2 },
        /* Medfield */
        { PCI_VDEVICE(INTEL, 0x0817), 3,},
        { PCI_VDEVICE(INTEL, 0x0818), 4 },
        { PCI_VDEVICE(INTEL, 0x0819), 5 },
        { PCI_VDEVICE(INTEL, 0x082C), 0 },
        { PCI_VDEVICE(INTEL, 0x082D), 1 },
        { PCI_VDEVICE(INTEL, 0x082E), 2 },
        { 0,}
};
MODULE_DEVICE_TABLE(pci, intel_mid_i2c_ids);

static struct pci_driver intel_mid_i2c_driver = {
        .name           = DRIVER_NAME,
        .id_table       = intel_mid_i2c_ids,
        .probe          = intel_mid_i2c_probe,
        .remove         = intel_mid_i2c_remove,
};

module_pci_driver(intel_mid_i2c_driver);

MODULE_AUTHOR("Ba Zheng <zheng.ba@intel.com>");
MODULE_DESCRIPTION("I2C driver for Moorestown Platform");
MODULE_LICENSE("GPL");
MODULE_VERSION(VERSION);