/*
 * Copyright (C) 2011 LAPIS Semiconductor Co., Ltd.
 *
 * 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; version 2 of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/i2c.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/types.h>
#include <linux/interrupt.h>
#include <linux/jiffies.h>
#include <linux/pci.h>
#include <linux/mutex.h>
#include <linux/ktime.h>
#include <linux/slab.h>

#define PCH_EVENT_SET   0       /* I2C Interrupt Event Set Status */
#define PCH_EVENT_NONE  1       /* I2C Interrupt Event Clear Status */
#define PCH_MAX_CLK             100000  /* Maximum Clock speed in MHz */
#define PCH_BUFFER_MODE_ENABLE  0x0002  /* flag for Buffer mode enable */
#define PCH_EEPROM_SW_RST_MODE_ENABLE   0x0008  /* EEPROM SW RST enable flag */

#define PCH_I2CSADR     0x00    /* I2C slave address register */
#define PCH_I2CCTL      0x04    /* I2C control register */
#define PCH_I2CSR       0x08    /* I2C status register */
#define PCH_I2CDR       0x0C    /* I2C data register */
#define PCH_I2CMON      0x10    /* I2C bus monitor register */
#define PCH_I2CBC       0x14    /* I2C bus transfer rate setup counter */
#define PCH_I2CMOD      0x18    /* I2C mode register */
#define PCH_I2CBUFSLV   0x1C    /* I2C buffer mode slave address register */
#define PCH_I2CBUFSUB   0x20    /* I2C buffer mode subaddress register */
#define PCH_I2CBUFFOR   0x24    /* I2C buffer mode format register */
#define PCH_I2CBUFCTL   0x28    /* I2C buffer mode control register */
#define PCH_I2CBUFMSK   0x2C    /* I2C buffer mode interrupt mask register */
#define PCH_I2CBUFSTA   0x30    /* I2C buffer mode status register */
#define PCH_I2CBUFLEV   0x34    /* I2C buffer mode level register */
#define PCH_I2CESRFOR   0x38    /* EEPROM software reset mode format register */
#define PCH_I2CESRCTL   0x3C    /* EEPROM software reset mode ctrl register */
#define PCH_I2CESRMSK   0x40    /* EEPROM software reset mode */
#define PCH_I2CESRSTA   0x44    /* EEPROM software reset mode status register */
#define PCH_I2CTMR      0x48    /* I2C timer register */
#define PCH_I2CSRST     0xFC    /* I2C reset register */
#define PCH_I2CNF       0xF8    /* I2C noise filter register */

#define BUS_IDLE_TIMEOUT        20
#define PCH_I2CCTL_I2CMEN       0x0080
#define TEN_BIT_ADDR_DEFAULT    0xF000
#define TEN_BIT_ADDR_MASK       0xF0
#define PCH_START               0x0020
#define PCH_RESTART             0x0004
#define PCH_ESR_START           0x0001
#define PCH_BUFF_START          0x1
#define PCH_REPSTART            0x0004
#define PCH_ACK                 0x0008
#define PCH_GETACK              0x0001
#define CLR_REG                 0x0
#define I2C_RD                  0x1
#define I2CMCF_BIT              0x0080
#define I2CMIF_BIT              0x0002
#define I2CMAL_BIT              0x0010
#define I2CBMFI_BIT             0x0001
#define I2CBMAL_BIT             0x0002
#define I2CBMNA_BIT             0x0004
#define I2CBMTO_BIT             0x0008
#define I2CBMIS_BIT             0x0010
#define I2CESRFI_BIT            0X0001
#define I2CESRTO_BIT            0x0002
#define I2CESRFIIE_BIT          0x1
#define I2CESRTOIE_BIT          0x2
#define I2CBMDZ_BIT             0x0040
#define I2CBMAG_BIT             0x0020
#define I2CMBB_BIT              0x0020
#define BUFFER_MODE_MASK        (I2CBMFI_BIT | I2CBMAL_BIT | I2CBMNA_BIT | \
                                I2CBMTO_BIT | I2CBMIS_BIT)
#define I2C_ADDR_MSK            0xFF
#define I2C_MSB_2B_MSK          0x300
#define FAST_MODE_CLK           400
#define FAST_MODE_EN            0x0001
#define SUB_ADDR_LEN_MAX        4
#define BUF_LEN_MAX             32
#define PCH_BUFFER_MODE         0x1
#define EEPROM_SW_RST_MODE      0x0002
#define NORMAL_INTR_ENBL        0x0300
#define EEPROM_RST_INTR_ENBL    (I2CESRFIIE_BIT | I2CESRTOIE_BIT)
#define EEPROM_RST_INTR_DISBL   0x0
#define BUFFER_MODE_INTR_ENBL   0x001F
#define BUFFER_MODE_INTR_DISBL  0x0
#define NORMAL_MODE             0x0
#define BUFFER_MODE             0x1
#define EEPROM_SR_MODE          0x2
#define I2C_TX_MODE             0x0010
#define PCH_BUF_TX              0xFFF7
#define PCH_BUF_RD              0x0008
#define I2C_ERROR_MASK  (I2CESRTO_EVENT | I2CBMIS_EVENT | I2CBMTO_EVENT | \
                        I2CBMNA_EVENT | I2CBMAL_EVENT | I2CMAL_EVENT)
#define I2CMAL_EVENT            0x0001
#define I2CMCF_EVENT            0x0002
#define I2CBMFI_EVENT           0x0004
#define I2CBMAL_EVENT           0x0008
#define I2CBMNA_EVENT           0x0010
#define I2CBMTO_EVENT           0x0020
#define I2CBMIS_EVENT           0x0040
#define I2CESRFI_EVENT          0x0080
#define I2CESRTO_EVENT          0x0100
#define PCI_DEVICE_ID_PCH_I2C   0x8817

#define pch_dbg(adap, fmt, arg...)  \
        dev_dbg(adap->pch_adapter.dev.parent, "%s :" fmt, __func__, ##arg)

#define pch_err(adap, fmt, arg...)  \
        dev_err(adap->pch_adapter.dev.parent, "%s :" fmt, __func__, ##arg)

#define pch_pci_err(pdev, fmt, arg...)  \
        dev_err(&pdev->dev, "%s :" fmt, __func__, ##arg)

#define pch_pci_dbg(pdev, fmt, arg...)  \
        dev_dbg(&pdev->dev, "%s :" fmt, __func__, ##arg)

/*
Set the number of I2C instance max
Intel EG20T PCH :               1ch
LAPIS Semiconductor ML7213 IOH :        2ch
LAPIS Semiconductor ML7831 IOH :        1ch
*/
#define PCH_I2C_MAX_DEV                 2

/**
 * struct i2c_algo_pch_data - for I2C driver functionalities
 * @pch_adapter:                stores the reference to i2c_adapter structure
 * @p_adapter_info:             stores the reference to adapter_info structure
 * @pch_base_address:           specifies the remapped base address
 * @pch_buff_mode_en:           specifies if buffer mode is enabled
 * @pch_event_flag:             specifies occurrence of interrupt events
 * @pch_i2c_xfer_in_progress:   specifies whether the transfer is completed
 */
struct i2c_algo_pch_data {
        struct i2c_adapter pch_adapter;
        struct adapter_info *p_adapter_info;
        void __iomem *pch_base_address;
        int pch_buff_mode_en;
        u32 pch_event_flag;
        bool pch_i2c_xfer_in_progress;
};

/**
 * struct adapter_info - This structure holds the adapter information for the
                         PCH i2c controller
 * @pch_data:           stores a list of i2c_algo_pch_data
 * @pch_i2c_suspended:  specifies whether the system is suspended or not
 *                      perhaps with more lines and words.
 * @ch_num:             specifies the number of i2c instance
 *
 * pch_data has as many elements as maximum I2C channels
 */
struct adapter_info {
        struct i2c_algo_pch_data pch_data[PCH_I2C_MAX_DEV];
        bool pch_i2c_suspended;
        int ch_num;
};


static int pch_i2c_speed = 100; /* I2C bus speed in Kbps */
static int pch_clk = 50000;     /* specifies I2C clock speed in KHz */
static wait_queue_head_t pch_event;
static DEFINE_MUTEX(pch_mutex);

/* Definition for ML7213 by LAPIS Semiconductor */
#define PCI_DEVICE_ID_ML7213_I2C        0x802D
#define PCI_DEVICE_ID_ML7223_I2C        0x8010
#define PCI_DEVICE_ID_ML7831_I2C        0x8817

static const struct pci_device_id pch_pcidev_id[] = {
        { PCI_VDEVICE(INTEL, PCI_DEVICE_ID_PCH_I2C),   1, },
        { PCI_VDEVICE(ROHM, PCI_DEVICE_ID_ML7213_I2C), 2, },
        { PCI_VDEVICE(ROHM, PCI_DEVICE_ID_ML7223_I2C), 1, },
        { PCI_VDEVICE(ROHM, PCI_DEVICE_ID_ML7831_I2C), 1, },
        {0,}
};

static irqreturn_t pch_i2c_handler(int irq, void *pData);

static inline void pch_setbit(void __iomem *addr, u32 offset, u32 bitmask)
{
        u32 val;
        val = ioread32(addr + offset);
        val |= bitmask;
        iowrite32(val, addr + offset);
}

static inline void pch_clrbit(void __iomem *addr, u32 offset, u32 bitmask)
{
        u32 val;
        val = ioread32(addr + offset);
        val &= (~bitmask);
        iowrite32(val, addr + offset);
}

/**
 * pch_i2c_init() - hardware initialization of I2C module
 * @adap:       Pointer to struct i2c_algo_pch_data.
 */
static void pch_i2c_init(struct i2c_algo_pch_data *adap)
{
        void __iomem *p = adap->pch_base_address;
        u32 pch_i2cbc;
        u32 pch_i2ctmr;
        u32 reg_value;

        /* reset I2C controller */
        iowrite32(0x01, p + PCH_I2CSRST);
        msleep(20);
        iowrite32(0x0, p + PCH_I2CSRST);

        /* Initialize I2C registers */
        iowrite32(0x21, p + PCH_I2CNF);

        pch_setbit(adap->pch_base_address, PCH_I2CCTL, PCH_I2CCTL_I2CMEN);

        if (pch_i2c_speed != 400)
                pch_i2c_speed = 100;

        reg_value = PCH_I2CCTL_I2CMEN;
        if (pch_i2c_speed == FAST_MODE_CLK) {
                reg_value |= FAST_MODE_EN;
                pch_dbg(adap, "Fast mode enabled\n");
        }

        if (pch_clk > PCH_MAX_CLK)
                pch_clk = 62500;

        pch_i2cbc = (pch_clk + (pch_i2c_speed * 4)) / (pch_i2c_speed * 8);
        /* Set transfer speed in I2CBC */
        iowrite32(pch_i2cbc, p + PCH_I2CBC);

        pch_i2ctmr = (pch_clk) / 8;
        iowrite32(pch_i2ctmr, p + PCH_I2CTMR);

        reg_value |= NORMAL_INTR_ENBL;  /* Enable interrupts in normal mode */
        iowrite32(reg_value, p + PCH_I2CCTL);

        pch_dbg(adap,
                "I2CCTL=%x pch_i2cbc=%x pch_i2ctmr=%x Enable interrupts\n",
                ioread32(p + PCH_I2CCTL), pch_i2cbc, pch_i2ctmr);

        init_waitqueue_head(&pch_event);
}

/**
 * pch_i2c_wait_for_bus_idle() - check the status of bus.
 * @adap:       Pointer to struct i2c_algo_pch_data.
 * @timeout:    waiting time counter (ms).
 */
static s32 pch_i2c_wait_for_bus_idle(struct i2c_algo_pch_data *adap,
                                     s32 timeout)
{
        void __iomem *p = adap->pch_base_address;
        int schedule = 0;
        unsigned long end = jiffies + msecs_to_jiffies(timeout);

        while (ioread32(p + PCH_I2CSR) & I2CMBB_BIT) {
                if (time_after(jiffies, end)) {
                        pch_dbg(adap, "I2CSR = %x\n", ioread32(p + PCH_I2CSR));
                        pch_err(adap, "%s: Timeout Error.return%d\n",
                                        __func__, -ETIME);
                        pch_i2c_init(adap);

                        return -ETIME;
                }

                if (!schedule)
                        /* Retry after some usecs */
                        udelay(5);
                else
                        /* Wait a bit more without consuming CPU */
                        usleep_range(20, 1000);

                schedule = 1;
        }

        return 0;
}

/**
 * pch_i2c_start() - Generate I2C start condition in normal mode.
 * @adap:       Pointer to struct i2c_algo_pch_data.
 *
 * Generate I2C start condition in normal mode by setting I2CCTL.I2CMSTA to 1.
 */
static void pch_i2c_start(struct i2c_algo_pch_data *adap)
{
        void __iomem *p = adap->pch_base_address;
        pch_dbg(adap, "I2CCTL = %x\n", ioread32(p + PCH_I2CCTL));
        pch_setbit(adap->pch_base_address, PCH_I2CCTL, PCH_START);
}

/**
 * pch_i2c_stop() - generate stop condition in normal mode.
 * @adap:       Pointer to struct i2c_algo_pch_data.
 */
static void pch_i2c_stop(struct i2c_algo_pch_data *adap)
{
        void __iomem *p = adap->pch_base_address;
        pch_dbg(adap, "I2CCTL = %x\n", ioread32(p + PCH_I2CCTL));
        /* clear the start bit */
        pch_clrbit(adap->pch_base_address, PCH_I2CCTL, PCH_START);
}

static int pch_i2c_wait_for_check_xfer(struct i2c_algo_pch_data *adap)
{
        long ret;
        void __iomem *p = adap->pch_base_address;

        ret = wait_event_timeout(pch_event,
                        (adap->pch_event_flag != 0), msecs_to_jiffies(1000));
        if (!ret) {
                pch_err(adap, "%s:wait-event timeout\n", __func__);
                adap->pch_event_flag = 0;
                pch_i2c_stop(adap);
                pch_i2c_init(adap);
                return -ETIMEDOUT;
        }

        if (adap->pch_event_flag & I2C_ERROR_MASK) {
                pch_err(adap, "Lost Arbitration\n");
                adap->pch_event_flag = 0;
                pch_clrbit(adap->pch_base_address, PCH_I2CSR, I2CMAL_BIT);
                pch_clrbit(adap->pch_base_address, PCH_I2CSR, I2CMIF_BIT);
                pch_i2c_init(adap);
                return -EAGAIN;
        }

        adap->pch_event_flag = 0;

        if (ioread32(p + PCH_I2CSR) & PCH_GETACK) {
                pch_dbg(adap, "Receive NACK for slave address setting\n");
                return -ENXIO;
        }

        return 0;
}

/**
 * pch_i2c_repstart() - generate repeated start condition in normal mode
 * @adap:       Pointer to struct i2c_algo_pch_data.
 */
static void pch_i2c_repstart(struct i2c_algo_pch_data *adap)
{
        void __iomem *p = adap->pch_base_address;
        pch_dbg(adap, "I2CCTL = %x\n", ioread32(p + PCH_I2CCTL));
        pch_setbit(adap->pch_base_address, PCH_I2CCTL, PCH_REPSTART);
}

/**
 * pch_i2c_writebytes() - write data to I2C bus in normal mode
 * @i2c_adap:   Pointer to the struct i2c_adapter.
 * @last:       specifies whether last message or not.
 *              In the case of compound mode it will be 1 for last message,
 *              otherwise 0.
 * @first:      specifies whether first message or not.
 *              1 for first message otherwise 0.
 */
static s32 pch_i2c_writebytes(struct i2c_adapter *i2c_adap,
                              struct i2c_msg *msgs, u32 last, u32 first)
{
        struct i2c_algo_pch_data *adap = i2c_adap->algo_data;
        u8 *buf;
        u32 length;
        u32 addr;
        u32 addr_2_msb;
        u32 addr_8_lsb;
        s32 wrcount;
        s32 rtn;
        void __iomem *p = adap->pch_base_address;

        length = msgs->len;
        buf = msgs->buf;
        addr = msgs->addr;

        /* enable master tx */
        pch_setbit(adap->pch_base_address, PCH_I2CCTL, I2C_TX_MODE);

        pch_dbg(adap, "I2CCTL = %x msgs->len = %d\n", ioread32(p + PCH_I2CCTL),
                length);

        if (first) {
                if (pch_i2c_wait_for_bus_idle(adap, BUS_IDLE_TIMEOUT) == -ETIME)
                        return -ETIME;
        }

        if (msgs->flags & I2C_M_TEN) {
                addr_2_msb = ((addr & I2C_MSB_2B_MSK) >> 7) & 0x06;
                iowrite32(addr_2_msb | TEN_BIT_ADDR_MASK, p + PCH_I2CDR);
                if (first)
                        pch_i2c_start(adap);

                rtn = pch_i2c_wait_for_check_xfer(adap);
                if (rtn)
                        return rtn;

                addr_8_lsb = (addr & I2C_ADDR_MSK);
                iowrite32(addr_8_lsb, p + PCH_I2CDR);
        } else {
                /* set 7 bit slave address and R/W bit as 0 */
                iowrite32(i2c_8bit_addr_from_msg(msgs), p + PCH_I2CDR);
                if (first)
                        pch_i2c_start(adap);
        }

        rtn = pch_i2c_wait_for_check_xfer(adap);
        if (rtn)
                return rtn;

        for (wrcount = 0; wrcount < length; ++wrcount) {
                /* write buffer value to I2C data register */
                iowrite32(buf[wrcount], p + PCH_I2CDR);
                pch_dbg(adap, "writing %x to Data register\n", buf[wrcount]);

                rtn = pch_i2c_wait_for_check_xfer(adap);
                if (rtn)
                        return rtn;

                pch_clrbit(adap->pch_base_address, PCH_I2CSR, I2CMCF_BIT);
                pch_clrbit(adap->pch_base_address, PCH_I2CSR, I2CMIF_BIT);
        }

        /* check if this is the last message */
        if (last)
                pch_i2c_stop(adap);
        else
                pch_i2c_repstart(adap);

        pch_dbg(adap, "return=%d\n", wrcount);

        return wrcount;
}

/**
 * pch_i2c_sendack() - send ACK
 * @adap:       Pointer to struct i2c_algo_pch_data.
 */
static void pch_i2c_sendack(struct i2c_algo_pch_data *adap)
{
        void __iomem *p = adap->pch_base_address;
        pch_dbg(adap, "I2CCTL = %x\n", ioread32(p + PCH_I2CCTL));
        pch_clrbit(adap->pch_base_address, PCH_I2CCTL, PCH_ACK);
}

/**
 * pch_i2c_sendnack() - send NACK
 * @adap:       Pointer to struct i2c_algo_pch_data.
 */
static void pch_i2c_sendnack(struct i2c_algo_pch_data *adap)
{
        void __iomem *p = adap->pch_base_address;
        pch_dbg(adap, "I2CCTL = %x\n", ioread32(p + PCH_I2CCTL));
        pch_setbit(adap->pch_base_address, PCH_I2CCTL, PCH_ACK);
}

/**
 * pch_i2c_restart() - Generate I2C restart condition in normal mode.
 * @adap:       Pointer to struct i2c_algo_pch_data.
 *
 * Generate I2C restart condition in normal mode by setting I2CCTL.I2CRSTA.
 */
static void pch_i2c_restart(struct i2c_algo_pch_data *adap)
{
        void __iomem *p = adap->pch_base_address;
        pch_dbg(adap, "I2CCTL = %x\n", ioread32(p + PCH_I2CCTL));
        pch_setbit(adap->pch_base_address, PCH_I2CCTL, PCH_RESTART);
}

/**
 * pch_i2c_readbytes() - read data  from I2C bus in normal mode.
 * @i2c_adap:   Pointer to the struct i2c_adapter.
 * @msgs:       Pointer to i2c_msg structure.
 * @last:       specifies whether last message or not.
 * @first:      specifies whether first message or not.
 */
static s32 pch_i2c_readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msgs,
                             u32 last, u32 first)
{
        struct i2c_algo_pch_data *adap = i2c_adap->algo_data;

        u8 *buf;
        u32 count;
        u32 length;
        u32 addr;
        u32 addr_2_msb;
        u32 addr_8_lsb;
        void __iomem *p = adap->pch_base_address;
        s32 rtn;

        length = msgs->len;
        buf = msgs->buf;
        addr = msgs->addr;

        /* enable master reception */
        pch_clrbit(adap->pch_base_address, PCH_I2CCTL, I2C_TX_MODE);

        if (first) {
                if (pch_i2c_wait_for_bus_idle(adap, BUS_IDLE_TIMEOUT) == -ETIME)
                        return -ETIME;
        }

        if (msgs->flags & I2C_M_TEN) {
                addr_2_msb = ((addr & I2C_MSB_2B_MSK) >> 7);
                iowrite32(addr_2_msb | TEN_BIT_ADDR_MASK, p + PCH_I2CDR);
                if (first)
                        pch_i2c_start(adap);

                rtn = pch_i2c_wait_for_check_xfer(adap);
                if (rtn)
                        return rtn;

                addr_8_lsb = (addr & I2C_ADDR_MSK);
                iowrite32(addr_8_lsb, p + PCH_I2CDR);

                pch_i2c_restart(adap);

                rtn = pch_i2c_wait_for_check_xfer(adap);
                if (rtn)
                        return rtn;

                addr_2_msb |= I2C_RD;
                iowrite32(addr_2_msb | TEN_BIT_ADDR_MASK, p + PCH_I2CDR);
        } else {
                /* 7 address bits + R/W bit */
                iowrite32(i2c_8bit_addr_from_msg(msgs), p + PCH_I2CDR);
        }

        /* check if it is the first message */
        if (first)
                pch_i2c_start(adap);

        rtn = pch_i2c_wait_for_check_xfer(adap);
        if (rtn)
                return rtn;

        if (length == 0) {
                pch_i2c_stop(adap);
                ioread32(p + PCH_I2CDR); /* Dummy read needs */

                count = length;
        } else {
                int read_index;
                int loop;
                pch_i2c_sendack(adap);

                /* Dummy read */
                for (loop = 1, read_index = 0; loop < length; loop++) {
                        buf[read_index] = ioread32(p + PCH_I2CDR);

                        if (loop != 1)
                                read_index++;

                        rtn = pch_i2c_wait_for_check_xfer(adap);
                        if (rtn)
                                return rtn;
                }       /* end for */

                pch_i2c_sendnack(adap);

                buf[read_index] = ioread32(p + PCH_I2CDR); /* Read final - 1 */

                if (length != 1)
                        read_index++;

                rtn = pch_i2c_wait_for_check_xfer(adap);
                if (rtn)
                        return rtn;

                if (last)
                        pch_i2c_stop(adap);
                else
                        pch_i2c_repstart(adap);

                buf[read_index++] = ioread32(p + PCH_I2CDR); /* Read Final */
                count = read_index;
        }

        return count;
}

/**
 * pch_i2c_cb() - Interrupt handler Call back function
 * @adap:       Pointer to struct i2c_algo_pch_data.
 */
static void pch_i2c_cb(struct i2c_algo_pch_data *adap)
{
        u32 sts;
        void __iomem *p = adap->pch_base_address;

        sts = ioread32(p + PCH_I2CSR);
        sts &= (I2CMAL_BIT | I2CMCF_BIT | I2CMIF_BIT);
        if (sts & I2CMAL_BIT)
                adap->pch_event_flag |= I2CMAL_EVENT;

        if (sts & I2CMCF_BIT)
                adap->pch_event_flag |= I2CMCF_EVENT;

        /* clear the applicable bits */
        pch_clrbit(adap->pch_base_address, PCH_I2CSR, sts);

        pch_dbg(adap, "PCH_I2CSR = %x\n", ioread32(p + PCH_I2CSR));

        wake_up(&pch_event);
}

/**
 * pch_i2c_handler() - interrupt handler for the PCH I2C controller
 * @irq:        irq number.
 * @pData:      cookie passed back to the handler function.
 */
static irqreturn_t pch_i2c_handler(int irq, void *pData)
{
        u32 reg_val;
        int flag;
        int i;
        struct adapter_info *adap_info = pData;
        void __iomem *p;
        u32 mode;

        for (i = 0, flag = 0; i < adap_info->ch_num; i++) {
                p = adap_info->pch_data[i].pch_base_address;
                mode = ioread32(p + PCH_I2CMOD);
                mode &= BUFFER_MODE | EEPROM_SR_MODE;
                if (mode != NORMAL_MODE) {
                        pch_err(adap_info->pch_data,
                                "I2C-%d mode(%d) is not supported\n", mode, i);
                        continue;
                }
                reg_val = ioread32(p + PCH_I2CSR);
                if (reg_val & (I2CMAL_BIT | I2CMCF_BIT | I2CMIF_BIT)) {
                        pch_i2c_cb(&adap_info->pch_data[i]);
                        flag = 1;
                }
        }

        return flag ? IRQ_HANDLED : IRQ_NONE;
}

/**
 * pch_i2c_xfer() - Reading adnd writing data through I2C bus
 * @i2c_adap:   Pointer to the struct i2c_adapter.
 * @msgs:       Pointer to i2c_msg structure.
 * @num:        number of messages.
 */
static s32 pch_i2c_xfer(struct i2c_adapter *i2c_adap,
                        struct i2c_msg *msgs, s32 num)
{
        struct i2c_msg *pmsg;
        u32 i = 0;
        u32 status;
        s32 ret;

        struct i2c_algo_pch_data *adap = i2c_adap->algo_data;

        ret = mutex_lock_interruptible(&pch_mutex);
        if (ret)
                return ret;

        if (adap->p_adapter_info->pch_i2c_suspended) {
                mutex_unlock(&pch_mutex);
                return -EBUSY;
        }

        pch_dbg(adap, "adap->p_adapter_info->pch_i2c_suspended is %d\n",
                adap->p_adapter_info->pch_i2c_suspended);
        /* transfer not completed */
        adap->pch_i2c_xfer_in_progress = true;

        for (i = 0; i < num && ret >= 0; i++) {
                pmsg = &msgs[i];
                pmsg->flags |= adap->pch_buff_mode_en;
                status = pmsg->flags;
                pch_dbg(adap,
                        "After invoking I2C_MODE_SEL :flag= 0x%x\n", status);

                if ((status & (I2C_M_RD)) != false) {
                        ret = pch_i2c_readbytes(i2c_adap, pmsg, (i + 1 == num),
                                                (i == 0));
                } else {
                        ret = pch_i2c_writebytes(i2c_adap, pmsg, (i + 1 == num),
                                                 (i == 0));
                }
        }

        adap->pch_i2c_xfer_in_progress = false; /* transfer completed */

        mutex_unlock(&pch_mutex);

        return (ret < 0) ? ret : num;
}

/**
 * pch_i2c_func() - return the functionality of the I2C driver
 * @adap:       Pointer to struct i2c_algo_pch_data.
 */
static u32 pch_i2c_func(struct i2c_adapter *adap)
{
        return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR;
}

static const struct i2c_algorithm pch_algorithm = {
        .master_xfer = pch_i2c_xfer,
        .functionality = pch_i2c_func
};

/**
 * pch_i2c_disbl_int() - Disable PCH I2C interrupts
 * @adap:       Pointer to struct i2c_algo_pch_data.
 */
static void pch_i2c_disbl_int(struct i2c_algo_pch_data *adap)
{
        void __iomem *p = adap->pch_base_address;

        pch_clrbit(adap->pch_base_address, PCH_I2CCTL, NORMAL_INTR_ENBL);

        iowrite32(EEPROM_RST_INTR_DISBL, p + PCH_I2CESRMSK);

        iowrite32(BUFFER_MODE_INTR_DISBL, p + PCH_I2CBUFMSK);
}

static int pch_i2c_probe(struct pci_dev *pdev,
                                   const struct pci_device_id *id)
{
        void __iomem *base_addr;
        int ret;
        int i, j;
        struct adapter_info *adap_info;
        struct i2c_adapter *pch_adap;

        pch_pci_dbg(pdev, "Entered.\n");

        adap_info = kzalloc((sizeof(struct adapter_info)), GFP_KERNEL);
        if (adap_info == NULL)
                return -ENOMEM;

        ret = pci_enable_device(pdev);
        if (ret) {
                pch_pci_err(pdev, "pci_enable_device FAILED\n");
                goto err_pci_enable;
        }

        ret = pci_request_regions(pdev, KBUILD_MODNAME);
        if (ret) {
                pch_pci_err(pdev, "pci_request_regions FAILED\n");
                goto err_pci_req;
        }

        base_addr = pci_iomap(pdev, 1, 0);

        if (base_addr == NULL) {
                pch_pci_err(pdev, "pci_iomap FAILED\n");
                ret = -ENOMEM;
                goto err_pci_iomap;
        }

        /* Set the number of I2C channel instance */
        adap_info->ch_num = id->driver_data;

        for (i = 0; i < adap_info->ch_num; i++) {
                pch_adap = &adap_info->pch_data[i].pch_adapter;
                adap_info->pch_i2c_suspended = false;

                adap_info->pch_data[i].p_adapter_info = adap_info;

                pch_adap->owner = THIS_MODULE;
                pch_adap->class = I2C_CLASS_HWMON;
                strlcpy(pch_adap->name, KBUILD_MODNAME, sizeof(pch_adap->name));
                pch_adap->algo = &pch_algorithm;
                pch_adap->algo_data = &adap_info->pch_data[i];

                /* base_addr + offset; */
                adap_info->pch_data[i].pch_base_address = base_addr + 0x100 * i;

                pch_adap->dev.of_node = pdev->dev.of_node;
                pch_adap->dev.parent = &pdev->dev;
        }

        ret = request_irq(pdev->irq, pch_i2c_handler, IRQF_SHARED,
                  KBUILD_MODNAME, adap_info);
        if (ret) {
                pch_pci_err(pdev, "request_irq FAILED\n");
                goto err_request_irq;
        }

        for (i = 0; i < adap_info->ch_num; i++) {
                pch_adap = &adap_info->pch_data[i].pch_adapter;

                pch_i2c_init(&adap_info->pch_data[i]);

                pch_adap->nr = i;
                ret = i2c_add_numbered_adapter(pch_adap);
                if (ret) {
                        pch_pci_err(pdev, "i2c_add_adapter[ch:%d] FAILED\n", i);
                        goto err_add_adapter;
                }
        }

        pci_set_drvdata(pdev, adap_info);
        pch_pci_dbg(pdev, "returns %d.\n", ret);
        return 0;

err_add_adapter:
        for (j = 0; j < i; j++)
                i2c_del_adapter(&adap_info->pch_data[j].pch_adapter);
        free_irq(pdev->irq, adap_info);
err_request_irq:
        pci_iounmap(pdev, base_addr);
err_pci_iomap:
        pci_release_regions(pdev);
err_pci_req:
        pci_disable_device(pdev);
err_pci_enable:
        kfree(adap_info);
        return ret;
}

static void pch_i2c_remove(struct pci_dev *pdev)
{
        int i;
        struct adapter_info *adap_info = pci_get_drvdata(pdev);

        free_irq(pdev->irq, adap_info);

        for (i = 0; i < adap_info->ch_num; i++) {
                pch_i2c_disbl_int(&adap_info->pch_data[i]);
                i2c_del_adapter(&adap_info->pch_data[i].pch_adapter);
        }

        if (adap_info->pch_data[0].pch_base_address)
                pci_iounmap(pdev, adap_info->pch_data[0].pch_base_address);

        for (i = 0; i < adap_info->ch_num; i++)
                adap_info->pch_data[i].pch_base_address = NULL;

        pci_release_regions(pdev);

        pci_disable_device(pdev);
        kfree(adap_info);
}

#ifdef CONFIG_PM
static int pch_i2c_suspend(struct pci_dev *pdev, pm_message_t state)
{
        int ret;
        int i;
        struct adapter_info *adap_info = pci_get_drvdata(pdev);
        void __iomem *p = adap_info->pch_data[0].pch_base_address;

        adap_info->pch_i2c_suspended = true;

        for (i = 0; i < adap_info->ch_num; i++) {
                while ((adap_info->pch_data[i].pch_i2c_xfer_in_progress)) {
                        /* Wait until all channel transfers are completed */
                        msleep(20);
                }
        }

        /* Disable the i2c interrupts */
        for (i = 0; i < adap_info->ch_num; i++)
                pch_i2c_disbl_int(&adap_info->pch_data[i]);

        pch_pci_dbg(pdev, "I2CSR = %x I2CBUFSTA = %x I2CESRSTA = %x "
                "invoked function pch_i2c_disbl_int successfully\n",
                ioread32(p + PCH_I2CSR), ioread32(p + PCH_I2CBUFSTA),
                ioread32(p + PCH_I2CESRSTA));

        ret = pci_save_state(pdev);

        if (ret) {
                pch_pci_err(pdev, "pci_save_state\n");
                return ret;
        }

        pci_enable_wake(pdev, PCI_D3hot, 0);
        pci_disable_device(pdev);
        pci_set_power_state(pdev, pci_choose_state(pdev, state));

        return 0;
}

static int pch_i2c_resume(struct pci_dev *pdev)
{
        int i;
        struct adapter_info *adap_info = pci_get_drvdata(pdev);

        pci_set_power_state(pdev, PCI_D0);
        pci_restore_state(pdev);

        if (pci_enable_device(pdev) < 0) {
                pch_pci_err(pdev, "pch_i2c_resume:pci_enable_device FAILED\n");
                return -EIO;
        }

        pci_enable_wake(pdev, PCI_D3hot, 0);

        for (i = 0; i < adap_info->ch_num; i++)
                pch_i2c_init(&adap_info->pch_data[i]);

        adap_info->pch_i2c_suspended = false;

        return 0;
}
#else
#define pch_i2c_suspend NULL
#define pch_i2c_resume NULL
#endif

static struct pci_driver pch_pcidriver = {
        .name = KBUILD_MODNAME,
        .id_table = pch_pcidev_id,
        .probe = pch_i2c_probe,
        .remove = pch_i2c_remove,
        .suspend = pch_i2c_suspend,
        .resume = pch_i2c_resume
};

module_pci_driver(pch_pcidriver);

MODULE_DESCRIPTION("Intel EG20T PCH/LAPIS Semico ML7213/ML7223/ML7831 IOH I2C");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Tomoya MORINAGA. <tomoya.rohm@gmail.com>");
module_param(pch_i2c_speed, int, (S_IRUSR | S_IWUSR));
module_param(pch_clk, int, (S_IRUSR | S_IWUSR));