/*
 * Copyright (C) 2014 Broadcom Corporation
 *
 * 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.
 *
 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
 * kind, whether express or implied; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

#define IDM_CTRL_DIRECT_OFFSET       0x00
#define CFG_OFFSET                   0x00
#define CFG_RESET_SHIFT              31
#define CFG_EN_SHIFT                 30
#define CFG_SLAVE_ADDR_0_SHIFT       28
#define CFG_M_RETRY_CNT_SHIFT        16
#define CFG_M_RETRY_CNT_MASK         0x0f

#define TIM_CFG_OFFSET               0x04
#define TIM_CFG_MODE_400_SHIFT       31
#define TIM_RAND_SLAVE_STRETCH_SHIFT      24
#define TIM_RAND_SLAVE_STRETCH_MASK       0x7f
#define TIM_PERIODIC_SLAVE_STRETCH_SHIFT  16
#define TIM_PERIODIC_SLAVE_STRETCH_MASK   0x7f

#define S_CFG_SMBUS_ADDR_OFFSET           0x08
#define S_CFG_EN_NIC_SMB_ADDR3_SHIFT      31
#define S_CFG_NIC_SMB_ADDR3_SHIFT         24
#define S_CFG_NIC_SMB_ADDR3_MASK          0x7f
#define S_CFG_EN_NIC_SMB_ADDR2_SHIFT      23
#define S_CFG_NIC_SMB_ADDR2_SHIFT         16
#define S_CFG_NIC_SMB_ADDR2_MASK          0x7f
#define S_CFG_EN_NIC_SMB_ADDR1_SHIFT      15
#define S_CFG_NIC_SMB_ADDR1_SHIFT         8
#define S_CFG_NIC_SMB_ADDR1_MASK          0x7f
#define S_CFG_EN_NIC_SMB_ADDR0_SHIFT      7
#define S_CFG_NIC_SMB_ADDR0_SHIFT         0
#define S_CFG_NIC_SMB_ADDR0_MASK          0x7f

#define M_FIFO_CTRL_OFFSET           0x0c
#define M_FIFO_RX_FLUSH_SHIFT        31
#define M_FIFO_TX_FLUSH_SHIFT        30
#define M_FIFO_RX_CNT_SHIFT          16
#define M_FIFO_RX_CNT_MASK           0x7f
#define M_FIFO_RX_THLD_SHIFT         8
#define M_FIFO_RX_THLD_MASK          0x3f

#define S_FIFO_CTRL_OFFSET           0x10
#define S_FIFO_RX_FLUSH_SHIFT        31
#define S_FIFO_TX_FLUSH_SHIFT        30
#define S_FIFO_RX_CNT_SHIFT          16
#define S_FIFO_RX_CNT_MASK           0x7f
#define S_FIFO_RX_THLD_SHIFT         8
#define S_FIFO_RX_THLD_MASK          0x3f

#define M_CMD_OFFSET                 0x30
#define M_CMD_START_BUSY_SHIFT       31
#define M_CMD_STATUS_SHIFT           25
#define M_CMD_STATUS_MASK            0x07
#define M_CMD_STATUS_SUCCESS         0x0
#define M_CMD_STATUS_LOST_ARB        0x1
#define M_CMD_STATUS_NACK_ADDR       0x2
#define M_CMD_STATUS_NACK_DATA       0x3
#define M_CMD_STATUS_TIMEOUT         0x4
#define M_CMD_STATUS_FIFO_UNDERRUN   0x5
#define M_CMD_STATUS_RX_FIFO_FULL    0x6
#define M_CMD_PROTOCOL_SHIFT         9
#define M_CMD_PROTOCOL_MASK          0xf
#define M_CMD_PROTOCOL_BLK_WR        0x7
#define M_CMD_PROTOCOL_BLK_RD        0x8
#define M_CMD_PEC_SHIFT              8
#define M_CMD_RD_CNT_SHIFT           0
#define M_CMD_RD_CNT_MASK            0xff

#define S_CMD_OFFSET                 0x34
#define S_CMD_START_BUSY_SHIFT       31
#define S_CMD_STATUS_SHIFT           23
#define S_CMD_STATUS_MASK            0x07
#define S_CMD_STATUS_SUCCESS         0x0
#define S_CMD_STATUS_TIMEOUT         0x5

#define IE_OFFSET                    0x38
#define IE_M_RX_FIFO_FULL_SHIFT      31
#define IE_M_RX_THLD_SHIFT           30
#define IE_M_START_BUSY_SHIFT        28
#define IE_M_TX_UNDERRUN_SHIFT       27
#define IE_S_RX_FIFO_FULL_SHIFT      26
#define IE_S_RX_THLD_SHIFT           25
#define IE_S_RX_EVENT_SHIFT          24
#define IE_S_START_BUSY_SHIFT        23
#define IE_S_TX_UNDERRUN_SHIFT       22
#define IE_S_RD_EVENT_SHIFT          21

#define IS_OFFSET                    0x3c
#define IS_M_RX_FIFO_FULL_SHIFT      31
#define IS_M_RX_THLD_SHIFT           30
#define IS_M_START_BUSY_SHIFT        28
#define IS_M_TX_UNDERRUN_SHIFT       27
#define IS_S_RX_FIFO_FULL_SHIFT      26
#define IS_S_RX_THLD_SHIFT           25
#define IS_S_RX_EVENT_SHIFT          24
#define IS_S_START_BUSY_SHIFT        23
#define IS_S_TX_UNDERRUN_SHIFT       22
#define IS_S_RD_EVENT_SHIFT          21

#define M_TX_OFFSET                  0x40
#define M_TX_WR_STATUS_SHIFT         31
#define M_TX_DATA_SHIFT              0
#define M_TX_DATA_MASK               0xff

#define M_RX_OFFSET                  0x44
#define M_RX_STATUS_SHIFT            30
#define M_RX_STATUS_MASK             0x03
#define M_RX_PEC_ERR_SHIFT           29
#define M_RX_DATA_SHIFT              0
#define M_RX_DATA_MASK               0xff

#define S_TX_OFFSET                  0x48
#define S_TX_WR_STATUS_SHIFT         31
#define S_TX_DATA_SHIFT              0
#define S_TX_DATA_MASK               0xff

#define S_RX_OFFSET                  0x4c
#define S_RX_STATUS_SHIFT            30
#define S_RX_STATUS_MASK             0x03
#define S_RX_PEC_ERR_SHIFT           29
#define S_RX_DATA_SHIFT              0
#define S_RX_DATA_MASK               0xff

#define I2C_TIMEOUT_MSEC             50000
#define M_TX_RX_FIFO_SIZE            64
#define M_RX_FIFO_MAX_THLD_VALUE     (M_TX_RX_FIFO_SIZE - 1)

#define M_RX_MAX_READ_LEN            255
#define M_RX_FIFO_THLD_VALUE         50

#define IE_M_ALL_INTERRUPT_SHIFT     27
#define IE_M_ALL_INTERRUPT_MASK      0x1e

#define SLAVE_READ_WRITE_BIT_MASK    0x1
#define SLAVE_READ_WRITE_BIT_SHIFT   0x1
#define SLAVE_MAX_SIZE_TRANSACTION   64
#define SLAVE_CLOCK_STRETCH_TIME     25

#define IE_S_ALL_INTERRUPT_SHIFT     21
#define IE_S_ALL_INTERRUPT_MASK      0x3f

enum i2c_slave_read_status {
        I2C_SLAVE_RX_FIFO_EMPTY = 0,
        I2C_SLAVE_RX_START,
        I2C_SLAVE_RX_DATA,
        I2C_SLAVE_RX_END,
};

enum bus_speed_index {
        I2C_SPD_100K = 0,
        I2C_SPD_400K,
};

enum bcm_iproc_i2c_type {
        IPROC_I2C,
        IPROC_I2C_NIC
};

struct bcm_iproc_i2c_dev {
        struct device *device;
        enum bcm_iproc_i2c_type type;
        int irq;

        void __iomem *base;
        void __iomem *idm_base;

        u32 ape_addr_mask;

        /* lock for indirect access through IDM */
        spinlock_t idm_lock;

        struct i2c_adapter adapter;
        unsigned int bus_speed;

        struct completion done;
        int xfer_is_done;

        struct i2c_msg *msg;

        struct i2c_client *slave;

        /* bytes that have been transferred */
        unsigned int tx_bytes;
        /* bytes that have been read */
        unsigned int rx_bytes;
        unsigned int thld_bytes;
};

/*
 * Can be expanded in the future if more interrupt status bits are utilized
 */
#define ISR_MASK (BIT(IS_M_START_BUSY_SHIFT) | BIT(IS_M_TX_UNDERRUN_SHIFT)\
                | BIT(IS_M_RX_THLD_SHIFT))

#define ISR_MASK_SLAVE (BIT(IS_S_START_BUSY_SHIFT)\
                | BIT(IS_S_RX_EVENT_SHIFT) | BIT(IS_S_RD_EVENT_SHIFT)\
                | BIT(IS_S_TX_UNDERRUN_SHIFT))

static int bcm_iproc_i2c_reg_slave(struct i2c_client *slave);
static int bcm_iproc_i2c_unreg_slave(struct i2c_client *slave);
static void bcm_iproc_i2c_enable_disable(struct bcm_iproc_i2c_dev *iproc_i2c,
                                         bool enable);

static inline u32 iproc_i2c_rd_reg(struct bcm_iproc_i2c_dev *iproc_i2c,
                                   u32 offset)
{
        u32 val;

        if (iproc_i2c->idm_base) {
                spin_lock(&iproc_i2c->idm_lock);
                writel(iproc_i2c->ape_addr_mask,
                       iproc_i2c->idm_base + IDM_CTRL_DIRECT_OFFSET);
                val = readl(iproc_i2c->base + offset);
                spin_unlock(&iproc_i2c->idm_lock);
        } else {
                val = readl(iproc_i2c->base + offset);
        }

        return val;
}

static inline void iproc_i2c_wr_reg(struct bcm_iproc_i2c_dev *iproc_i2c,
                                    u32 offset, u32 val)
{
        if (iproc_i2c->idm_base) {
                spin_lock(&iproc_i2c->idm_lock);
                writel(iproc_i2c->ape_addr_mask,
                       iproc_i2c->idm_base + IDM_CTRL_DIRECT_OFFSET);
                writel(val, iproc_i2c->base + offset);
                spin_unlock(&iproc_i2c->idm_lock);
        } else {
                writel(val, iproc_i2c->base + offset);
        }
}

static void bcm_iproc_i2c_slave_init(
        struct bcm_iproc_i2c_dev *iproc_i2c, bool need_reset)
{
        u32 val;

        if (need_reset) {
                /* put controller in reset */
                val = iproc_i2c_rd_reg(iproc_i2c, CFG_OFFSET);
                val |= BIT(CFG_RESET_SHIFT);
                iproc_i2c_wr_reg(iproc_i2c, CFG_OFFSET, val);

                /* wait 100 usec per spec */
                udelay(100);

                /* bring controller out of reset */
                val &= ~(BIT(CFG_RESET_SHIFT));
                iproc_i2c_wr_reg(iproc_i2c, CFG_OFFSET, val);
        }

        /* flush TX/RX FIFOs */
        val = (BIT(S_FIFO_RX_FLUSH_SHIFT) | BIT(S_FIFO_TX_FLUSH_SHIFT));
        iproc_i2c_wr_reg(iproc_i2c, S_FIFO_CTRL_OFFSET, val);

        /* Maximum slave stretch time */
        val = iproc_i2c_rd_reg(iproc_i2c, TIM_CFG_OFFSET);
        val &= ~(TIM_RAND_SLAVE_STRETCH_MASK << TIM_RAND_SLAVE_STRETCH_SHIFT);
        val |= (SLAVE_CLOCK_STRETCH_TIME << TIM_RAND_SLAVE_STRETCH_SHIFT);
        iproc_i2c_wr_reg(iproc_i2c, TIM_CFG_OFFSET, val);

        /* Configure the slave address */
        val = iproc_i2c_rd_reg(iproc_i2c, S_CFG_SMBUS_ADDR_OFFSET);
        val |= BIT(S_CFG_EN_NIC_SMB_ADDR3_SHIFT);
        val &= ~(S_CFG_NIC_SMB_ADDR3_MASK << S_CFG_NIC_SMB_ADDR3_SHIFT);
        val |= (iproc_i2c->slave->addr << S_CFG_NIC_SMB_ADDR3_SHIFT);
        iproc_i2c_wr_reg(iproc_i2c, S_CFG_SMBUS_ADDR_OFFSET, val);

        /* clear all pending slave interrupts */
        iproc_i2c_wr_reg(iproc_i2c, IS_OFFSET, ISR_MASK_SLAVE);

        /* Enable interrupt register to indicate a valid byte in receive fifo */
        val = BIT(IE_S_RX_EVENT_SHIFT);
        /* Enable interrupt register for the Slave BUSY command */
        val |= BIT(IE_S_START_BUSY_SHIFT);
        iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, val);
}

static void bcm_iproc_i2c_check_slave_status(
        struct bcm_iproc_i2c_dev *iproc_i2c)
{
        u32 val;

        val = iproc_i2c_rd_reg(iproc_i2c, S_CMD_OFFSET);
        /* status is valid only when START_BUSY is cleared after it was set */
        if (val & BIT(S_CMD_START_BUSY_SHIFT))
                return;

        val = (val >> S_CMD_STATUS_SHIFT) & S_CMD_STATUS_MASK;
        if (val == S_CMD_STATUS_TIMEOUT) {
                dev_err(iproc_i2c->device, "slave random stretch time timeout\n");

                /* re-initialize i2c for recovery */
                bcm_iproc_i2c_enable_disable(iproc_i2c, false);
                bcm_iproc_i2c_slave_init(iproc_i2c, true);
                bcm_iproc_i2c_enable_disable(iproc_i2c, true);
        }
}

static bool bcm_iproc_i2c_slave_isr(struct bcm_iproc_i2c_dev *iproc_i2c,
                                    u32 status)
{
        u32 val;
        u8 value, rx_status;

        /* Slave RX byte receive */
        if (status & BIT(IS_S_RX_EVENT_SHIFT)) {
                val = iproc_i2c_rd_reg(iproc_i2c, S_RX_OFFSET);
                rx_status = (val >> S_RX_STATUS_SHIFT) & S_RX_STATUS_MASK;
                if (rx_status == I2C_SLAVE_RX_START) {
                        /* Start of SMBUS for Master write */
                        i2c_slave_event(iproc_i2c->slave,
                                        I2C_SLAVE_WRITE_REQUESTED, &value);

                        val = iproc_i2c_rd_reg(iproc_i2c, S_RX_OFFSET);
                        value = (u8)((val >> S_RX_DATA_SHIFT) & S_RX_DATA_MASK);
                        i2c_slave_event(iproc_i2c->slave,
                                        I2C_SLAVE_WRITE_RECEIVED, &value);
                } else if (status & BIT(IS_S_RD_EVENT_SHIFT)) {
                        /* Start of SMBUS for Master Read */
                        i2c_slave_event(iproc_i2c->slave,
                                        I2C_SLAVE_READ_REQUESTED, &value);
                        iproc_i2c_wr_reg(iproc_i2c, S_TX_OFFSET, value);

                        val = BIT(S_CMD_START_BUSY_SHIFT);
                        iproc_i2c_wr_reg(iproc_i2c, S_CMD_OFFSET, val);

                        /*
                         * Enable interrupt for TX FIFO becomes empty and
                         * less than PKT_LENGTH bytes were output on the SMBUS
                         */
                        val = iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET);
                        val |= BIT(IE_S_TX_UNDERRUN_SHIFT);
                        iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, val);
                } else {
                        /* Master write other than start */
                        value = (u8)((val >> S_RX_DATA_SHIFT) & S_RX_DATA_MASK);
                        i2c_slave_event(iproc_i2c->slave,
                                        I2C_SLAVE_WRITE_RECEIVED, &value);
                }
        } else if (status & BIT(IS_S_TX_UNDERRUN_SHIFT)) {
                /* Master read other than start */
                i2c_slave_event(iproc_i2c->slave,
                                I2C_SLAVE_READ_PROCESSED, &value);

                iproc_i2c_wr_reg(iproc_i2c, S_TX_OFFSET, value);
                val = BIT(S_CMD_START_BUSY_SHIFT);
                iproc_i2c_wr_reg(iproc_i2c, S_CMD_OFFSET, val);
        }

        /* Stop */
        if (status & BIT(IS_S_START_BUSY_SHIFT)) {
                i2c_slave_event(iproc_i2c->slave, I2C_SLAVE_STOP, &value);
                /*
                 * Enable interrupt for TX FIFO becomes empty and
                 * less than PKT_LENGTH bytes were output on the SMBUS
                 */
                val = iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET);
                val &= ~BIT(IE_S_TX_UNDERRUN_SHIFT);
                iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, val);
        }

        /* clear interrupt status */
        iproc_i2c_wr_reg(iproc_i2c, IS_OFFSET, status);

        bcm_iproc_i2c_check_slave_status(iproc_i2c);
        return true;
}

static void bcm_iproc_i2c_read_valid_bytes(struct bcm_iproc_i2c_dev *iproc_i2c)
{
        struct i2c_msg *msg = iproc_i2c->msg;
        uint32_t val;

        /* Read valid data from RX FIFO */
        while (iproc_i2c->rx_bytes < msg->len) {
                val = iproc_i2c_rd_reg(iproc_i2c, M_RX_OFFSET);

                /* rx fifo empty */
                if (!((val >> M_RX_STATUS_SHIFT) & M_RX_STATUS_MASK))
                        break;

                msg->buf[iproc_i2c->rx_bytes] =
                        (val >> M_RX_DATA_SHIFT) & M_RX_DATA_MASK;
                iproc_i2c->rx_bytes++;
        }
}

static void bcm_iproc_i2c_send(struct bcm_iproc_i2c_dev *iproc_i2c)
{
        struct i2c_msg *msg = iproc_i2c->msg;
        unsigned int tx_bytes = msg->len - iproc_i2c->tx_bytes;
        unsigned int i;
        u32 val;

        /* can only fill up to the FIFO size */
        tx_bytes = min_t(unsigned int, tx_bytes, M_TX_RX_FIFO_SIZE);
        for (i = 0; i < tx_bytes; i++) {
                /* start from where we left over */
                unsigned int idx = iproc_i2c->tx_bytes + i;

                val = msg->buf[idx];

                /* mark the last byte */
                if (idx == msg->len - 1) {
                        val |= BIT(M_TX_WR_STATUS_SHIFT);

                        if (iproc_i2c->irq) {
                                u32 tmp;

                                /*
                                 * Since this is the last byte, we should now
                                 * disable TX FIFO underrun interrupt
                                 */
                                tmp = iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET);
                                tmp &= ~BIT(IE_M_TX_UNDERRUN_SHIFT);
                                iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET,
                                                 tmp);
                        }
                }

                /* load data into TX FIFO */
                iproc_i2c_wr_reg(iproc_i2c, M_TX_OFFSET, val);
        }

        /* update number of transferred bytes */
        iproc_i2c->tx_bytes += tx_bytes;
}

static void bcm_iproc_i2c_read(struct bcm_iproc_i2c_dev *iproc_i2c)
{
        struct i2c_msg *msg = iproc_i2c->msg;
        u32 bytes_left, val;

        bcm_iproc_i2c_read_valid_bytes(iproc_i2c);
        bytes_left = msg->len - iproc_i2c->rx_bytes;
        if (bytes_left == 0) {
                if (iproc_i2c->irq) {
                        /* finished reading all data, disable rx thld event */
                        val = iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET);
                        val &= ~BIT(IS_M_RX_THLD_SHIFT);
                        iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, val);
                }
        } else if (bytes_left < iproc_i2c->thld_bytes) {
                /* set bytes left as threshold */
                val = iproc_i2c_rd_reg(iproc_i2c, M_FIFO_CTRL_OFFSET);
                val &= ~(M_FIFO_RX_THLD_MASK << M_FIFO_RX_THLD_SHIFT);
                val |= (bytes_left << M_FIFO_RX_THLD_SHIFT);
                iproc_i2c_wr_reg(iproc_i2c, M_FIFO_CTRL_OFFSET, val);
                iproc_i2c->thld_bytes = bytes_left;
        }
        /*
         * bytes_left >= iproc_i2c->thld_bytes,
         * hence no need to change the THRESHOLD SET.
         * It will remain as iproc_i2c->thld_bytes itself
         */
}

static void bcm_iproc_i2c_process_m_event(struct bcm_iproc_i2c_dev *iproc_i2c,
                                          u32 status)
{
        /* TX FIFO is empty and we have more data to send */
        if (status & BIT(IS_M_TX_UNDERRUN_SHIFT))
                bcm_iproc_i2c_send(iproc_i2c);

        /* RX FIFO threshold is reached and data needs to be read out */
        if (status & BIT(IS_M_RX_THLD_SHIFT))
                bcm_iproc_i2c_read(iproc_i2c);

        /* transfer is done */
        if (status & BIT(IS_M_START_BUSY_SHIFT)) {
                iproc_i2c->xfer_is_done = 1;
                if (iproc_i2c->irq)
                        complete(&iproc_i2c->done);
        }
}

static irqreturn_t bcm_iproc_i2c_isr(int irq, void *data)
{
        struct bcm_iproc_i2c_dev *iproc_i2c = data;
        u32 status = iproc_i2c_rd_reg(iproc_i2c, IS_OFFSET);
        bool ret;
        u32 sl_status = status & ISR_MASK_SLAVE;

        if (sl_status) {
                ret = bcm_iproc_i2c_slave_isr(iproc_i2c, sl_status);
                if (ret)
                        return IRQ_HANDLED;
                else
                        return IRQ_NONE;
        }

        status &= ISR_MASK;
        if (!status)
                return IRQ_NONE;

        /* process all master based events */
        bcm_iproc_i2c_process_m_event(iproc_i2c, status);
        iproc_i2c_wr_reg(iproc_i2c, IS_OFFSET, status);

        return IRQ_HANDLED;
}

static int bcm_iproc_i2c_init(struct bcm_iproc_i2c_dev *iproc_i2c)
{
        u32 val;

        /* put controller in reset */
        val = iproc_i2c_rd_reg(iproc_i2c, CFG_OFFSET);
        val |= BIT(CFG_RESET_SHIFT);
        val &= ~(BIT(CFG_EN_SHIFT));
        iproc_i2c_wr_reg(iproc_i2c, CFG_OFFSET, val);

        /* wait 100 usec per spec */
        udelay(100);

        /* bring controller out of reset */
        val &= ~(BIT(CFG_RESET_SHIFT));
        iproc_i2c_wr_reg(iproc_i2c, CFG_OFFSET, val);

        /* flush TX/RX FIFOs and set RX FIFO threshold to zero */
        val = (BIT(M_FIFO_RX_FLUSH_SHIFT) | BIT(M_FIFO_TX_FLUSH_SHIFT));
        iproc_i2c_wr_reg(iproc_i2c, M_FIFO_CTRL_OFFSET, val);
        /* disable all interrupts */
        val = iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET);
        val &= ~(IE_M_ALL_INTERRUPT_MASK <<
                        IE_M_ALL_INTERRUPT_SHIFT);
        iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, val);

        /* clear all pending interrupts */
        iproc_i2c_wr_reg(iproc_i2c, IS_OFFSET, 0xffffffff);

        return 0;
}

static void bcm_iproc_i2c_enable_disable(struct bcm_iproc_i2c_dev *iproc_i2c,
                                         bool enable)
{
        u32 val;

        val = iproc_i2c_rd_reg(iproc_i2c, CFG_OFFSET);
        if (enable)
                val |= BIT(CFG_EN_SHIFT);
        else
                val &= ~BIT(CFG_EN_SHIFT);
        iproc_i2c_wr_reg(iproc_i2c, CFG_OFFSET, val);
}

static int bcm_iproc_i2c_check_status(struct bcm_iproc_i2c_dev *iproc_i2c,
                                      struct i2c_msg *msg)
{
        u32 val;

        val = iproc_i2c_rd_reg(iproc_i2c, M_CMD_OFFSET);
        val = (val >> M_CMD_STATUS_SHIFT) & M_CMD_STATUS_MASK;

        switch (val) {
        case M_CMD_STATUS_SUCCESS:
                return 0;

        case M_CMD_STATUS_LOST_ARB:
                dev_dbg(iproc_i2c->device, "lost bus arbitration\n");
                return -EAGAIN;

        case M_CMD_STATUS_NACK_ADDR:
                dev_dbg(iproc_i2c->device, "NAK addr:0x%02x\n", msg->addr);
                return -ENXIO;

        case M_CMD_STATUS_NACK_DATA:
                dev_dbg(iproc_i2c->device, "NAK data\n");
                return -ENXIO;

        case M_CMD_STATUS_TIMEOUT:
                dev_dbg(iproc_i2c->device, "bus timeout\n");
                return -ETIMEDOUT;

        case M_CMD_STATUS_FIFO_UNDERRUN:
                dev_dbg(iproc_i2c->device, "FIFO under-run\n");
                return -ENXIO;

        case M_CMD_STATUS_RX_FIFO_FULL:
                dev_dbg(iproc_i2c->device, "RX FIFO full\n");
                return -ETIMEDOUT;

        default:
                dev_dbg(iproc_i2c->device, "unknown error code=%d\n", val);

                /* re-initialize i2c for recovery */
                bcm_iproc_i2c_enable_disable(iproc_i2c, false);
                bcm_iproc_i2c_init(iproc_i2c);
                bcm_iproc_i2c_enable_disable(iproc_i2c, true);

                return -EIO;
        }
}

static int bcm_iproc_i2c_xfer_wait(struct bcm_iproc_i2c_dev *iproc_i2c,
                                   struct i2c_msg *msg,
                                   u32 cmd)
{
        unsigned long time_left = msecs_to_jiffies(I2C_TIMEOUT_MSEC);
        u32 val, status;
        int ret;

        iproc_i2c_wr_reg(iproc_i2c, M_CMD_OFFSET, cmd);

        if (iproc_i2c->irq) {
                time_left = wait_for_completion_timeout(&iproc_i2c->done,
                                                        time_left);
                /* disable all interrupts */
                iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, 0);
                /* read it back to flush the write */
                iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET);
                /* make sure the interrupt handler isn't running */
                synchronize_irq(iproc_i2c->irq);

        } else { /* polling mode */
                unsigned long timeout = jiffies + time_left;

                do {
                        status = iproc_i2c_rd_reg(iproc_i2c,
                                                  IS_OFFSET) & ISR_MASK;
                        bcm_iproc_i2c_process_m_event(iproc_i2c, status);
                        iproc_i2c_wr_reg(iproc_i2c, IS_OFFSET, status);

                        if (time_after(jiffies, timeout)) {
                                time_left = 0;
                                break;
                        }

                        cpu_relax();
                        cond_resched();
                } while (!iproc_i2c->xfer_is_done);
        }

        if (!time_left && !iproc_i2c->xfer_is_done) {
                dev_err(iproc_i2c->device, "transaction timed out\n");

                /* flush both TX/RX FIFOs */
                val = BIT(M_FIFO_RX_FLUSH_SHIFT) | BIT(M_FIFO_TX_FLUSH_SHIFT);
                iproc_i2c_wr_reg(iproc_i2c, M_FIFO_CTRL_OFFSET, val);
                return -ETIMEDOUT;
        }

        ret = bcm_iproc_i2c_check_status(iproc_i2c, msg);
        if (ret) {
                /* flush both TX/RX FIFOs */
                val = BIT(M_FIFO_RX_FLUSH_SHIFT) | BIT(M_FIFO_TX_FLUSH_SHIFT);
                iproc_i2c_wr_reg(iproc_i2c, M_FIFO_CTRL_OFFSET, val);
                return ret;
        }

        return 0;
}

static int bcm_iproc_i2c_xfer_single_msg(struct bcm_iproc_i2c_dev *iproc_i2c,
                                         struct i2c_msg *msg)
{
        int i;
        u8 addr;
        u32 val, tmp, val_intr_en;
        unsigned int tx_bytes;

        /* check if bus is busy */
        if (!!(iproc_i2c_rd_reg(iproc_i2c,
                                M_CMD_OFFSET) & BIT(M_CMD_START_BUSY_SHIFT))) {
                dev_warn(iproc_i2c->device, "bus is busy\n");
                return -EBUSY;
        }

        iproc_i2c->msg = msg;

        /* format and load slave address into the TX FIFO */
        addr = i2c_8bit_addr_from_msg(msg);
        iproc_i2c_wr_reg(iproc_i2c, M_TX_OFFSET, addr);

        /*
         * For a write transaction, load data into the TX FIFO. Only allow
         * loading up to TX FIFO size - 1 bytes of data since the first byte
         * has been used up by the slave address
         */
        tx_bytes = min_t(unsigned int, msg->len, M_TX_RX_FIFO_SIZE - 1);
        if (!(msg->flags & I2C_M_RD)) {
                for (i = 0; i < tx_bytes; i++) {
                        val = msg->buf[i];

                        /* mark the last byte */
                        if (i == msg->len - 1)
                                val |= BIT(M_TX_WR_STATUS_SHIFT);

                        iproc_i2c_wr_reg(iproc_i2c, M_TX_OFFSET, val);
                }
                iproc_i2c->tx_bytes = tx_bytes;
        }

        /* mark as incomplete before starting the transaction */
        if (iproc_i2c->irq)
                reinit_completion(&iproc_i2c->done);

        iproc_i2c->xfer_is_done = 0;

        /*
         * Enable the "start busy" interrupt, which will be triggered after the
         * transaction is done, i.e., the internal start_busy bit, transitions
         * from 1 to 0.
         */
        val_intr_en = BIT(IE_M_START_BUSY_SHIFT);

        /*
         * If TX data size is larger than the TX FIFO, need to enable TX
         * underrun interrupt, which will be triggerred when the TX FIFO is
         * empty. When that happens we can then pump more data into the FIFO
         */
        if (!(msg->flags & I2C_M_RD) &&
            msg->len > iproc_i2c->tx_bytes)
                val_intr_en |= BIT(IE_M_TX_UNDERRUN_SHIFT);

        /*
         * Now we can activate the transfer. For a read operation, specify the
         * number of bytes to read
         */
        val = BIT(M_CMD_START_BUSY_SHIFT);
        if (msg->flags & I2C_M_RD) {
                iproc_i2c->rx_bytes = 0;
                if (msg->len > M_RX_FIFO_MAX_THLD_VALUE)
                        iproc_i2c->thld_bytes = M_RX_FIFO_THLD_VALUE;
                else
                        iproc_i2c->thld_bytes = msg->len;

                /* set threshold value */
                tmp = iproc_i2c_rd_reg(iproc_i2c, M_FIFO_CTRL_OFFSET);
                tmp &= ~(M_FIFO_RX_THLD_MASK << M_FIFO_RX_THLD_SHIFT);
                tmp |= iproc_i2c->thld_bytes << M_FIFO_RX_THLD_SHIFT;
                iproc_i2c_wr_reg(iproc_i2c, M_FIFO_CTRL_OFFSET, tmp);

                /* enable the RX threshold interrupt */
                val_intr_en |= BIT(IE_M_RX_THLD_SHIFT);

                val |= (M_CMD_PROTOCOL_BLK_RD << M_CMD_PROTOCOL_SHIFT) |
                       (msg->len << M_CMD_RD_CNT_SHIFT);
        } else {
                val |= (M_CMD_PROTOCOL_BLK_WR << M_CMD_PROTOCOL_SHIFT);
        }

        if (iproc_i2c->irq)
                iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, val_intr_en);

        return bcm_iproc_i2c_xfer_wait(iproc_i2c, msg, val);
}

static int bcm_iproc_i2c_xfer(struct i2c_adapter *adapter,
                              struct i2c_msg msgs[], int num)
{
        struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adapter);
        int ret, i;

        /* go through all messages */
        for (i = 0; i < num; i++) {
                ret = bcm_iproc_i2c_xfer_single_msg(iproc_i2c, &msgs[i]);
                if (ret) {
                        dev_dbg(iproc_i2c->device, "xfer failed\n");
                        return ret;
                }
        }

        return num;
}

static uint32_t bcm_iproc_i2c_functionality(struct i2c_adapter *adap)
{
        u32 val;

        /* We do not support the SMBUS Quick command */
        val = I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);

        if (adap->algo->reg_slave)
                val |= I2C_FUNC_SLAVE;

        return val;
}

static struct i2c_algorithm bcm_iproc_algo = {
        .master_xfer = bcm_iproc_i2c_xfer,
        .functionality = bcm_iproc_i2c_functionality,
        .reg_slave = bcm_iproc_i2c_reg_slave,
        .unreg_slave = bcm_iproc_i2c_unreg_slave,
};

static const struct i2c_adapter_quirks bcm_iproc_i2c_quirks = {
        .max_read_len = M_RX_MAX_READ_LEN,
};

static int bcm_iproc_i2c_cfg_speed(struct bcm_iproc_i2c_dev *iproc_i2c)
{
        unsigned int bus_speed;
        u32 val;
        int ret = of_property_read_u32(iproc_i2c->device->of_node,
                                       "clock-frequency", &bus_speed);
        if (ret < 0) {
                dev_info(iproc_i2c->device,
                        "unable to interpret clock-frequency DT property\n");
                bus_speed = 100000;
        }

        if (bus_speed < 100000) {
                dev_err(iproc_i2c->device, "%d Hz bus speed not supported\n",
                        bus_speed);
                dev_err(iproc_i2c->device,
                        "valid speeds are 100khz and 400khz\n");
                return -EINVAL;
        } else if (bus_speed < 400000) {
                bus_speed = 100000;
        } else {
                bus_speed = 400000;
        }

        iproc_i2c->bus_speed = bus_speed;
        val = iproc_i2c_rd_reg(iproc_i2c, TIM_CFG_OFFSET);
        val &= ~BIT(TIM_CFG_MODE_400_SHIFT);
        val |= (bus_speed == 400000) << TIM_CFG_MODE_400_SHIFT;
        iproc_i2c_wr_reg(iproc_i2c, TIM_CFG_OFFSET, val);

        dev_info(iproc_i2c->device, "bus set to %u Hz\n", bus_speed);

        return 0;
}

static int bcm_iproc_i2c_probe(struct platform_device *pdev)
{
        int irq, ret = 0;
        struct bcm_iproc_i2c_dev *iproc_i2c;
        struct i2c_adapter *adap;
        struct resource *res;

        iproc_i2c = devm_kzalloc(&pdev->dev, sizeof(*iproc_i2c),
                                 GFP_KERNEL);
        if (!iproc_i2c)
                return -ENOMEM;

        platform_set_drvdata(pdev, iproc_i2c);
        iproc_i2c->device = &pdev->dev;
        iproc_i2c->type =
                (enum bcm_iproc_i2c_type)of_device_get_match_data(&pdev->dev);
        init_completion(&iproc_i2c->done);

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        iproc_i2c->base = devm_ioremap_resource(iproc_i2c->device, res);
        if (IS_ERR(iproc_i2c->base))
                return PTR_ERR(iproc_i2c->base);

        if (iproc_i2c->type == IPROC_I2C_NIC) {
                res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
                iproc_i2c->idm_base = devm_ioremap_resource(iproc_i2c->device,
                                                            res);
                if (IS_ERR(iproc_i2c->idm_base))
                        return PTR_ERR(iproc_i2c->idm_base);

                ret = of_property_read_u32(iproc_i2c->device->of_node,
                                           "brcm,ape-hsls-addr-mask",
                                           &iproc_i2c->ape_addr_mask);
                if (ret < 0) {
                        dev_err(iproc_i2c->device,
                                "'brcm,ape-hsls-addr-mask' missing\n");
                        return -EINVAL;
                }

                spin_lock_init(&iproc_i2c->idm_lock);

                /* no slave support */
                bcm_iproc_algo.reg_slave = NULL;
                bcm_iproc_algo.unreg_slave = NULL;
        }

        ret = bcm_iproc_i2c_init(iproc_i2c);
        if (ret)
                return ret;

        ret = bcm_iproc_i2c_cfg_speed(iproc_i2c);
        if (ret)
                return ret;

        irq = platform_get_irq(pdev, 0);
        if (irq > 0) {
                ret = devm_request_irq(iproc_i2c->device, irq,
                                       bcm_iproc_i2c_isr, 0, pdev->name,
                                       iproc_i2c);
                if (ret < 0) {
                        dev_err(iproc_i2c->device,
                                "unable to request irq %i\n", irq);
                        return ret;
                }

                iproc_i2c->irq = irq;
        } else {
                dev_warn(iproc_i2c->device,
                         "no irq resource, falling back to poll mode\n");
        }

        bcm_iproc_i2c_enable_disable(iproc_i2c, true);

        adap = &iproc_i2c->adapter;
        i2c_set_adapdata(adap, iproc_i2c);
        snprintf(adap->name, sizeof(adap->name),
                "Broadcom iProc (%s)",
                of_node_full_name(iproc_i2c->device->of_node));
        adap->algo = &bcm_iproc_algo;
        adap->quirks = &bcm_iproc_i2c_quirks;
        adap->dev.parent = &pdev->dev;
        adap->dev.of_node = pdev->dev.of_node;

        return i2c_add_adapter(adap);
}

static int bcm_iproc_i2c_remove(struct platform_device *pdev)
{
        struct bcm_iproc_i2c_dev *iproc_i2c = platform_get_drvdata(pdev);

        if (iproc_i2c->irq) {
                /*
                 * Make sure there's no pending interrupt when we remove the
                 * adapter
                 */
                iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, 0);
                iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET);
                synchronize_irq(iproc_i2c->irq);
        }

        i2c_del_adapter(&iproc_i2c->adapter);
        bcm_iproc_i2c_enable_disable(iproc_i2c, false);

        return 0;
}

#ifdef CONFIG_PM_SLEEP

static int bcm_iproc_i2c_suspend(struct device *dev)
{
        struct bcm_iproc_i2c_dev *iproc_i2c = dev_get_drvdata(dev);

        if (iproc_i2c->irq) {
                /*
                 * Make sure there's no pending interrupt when we go into
                 * suspend
                 */
                iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, 0);
                iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET);
                synchronize_irq(iproc_i2c->irq);
        }

        /* now disable the controller */
        bcm_iproc_i2c_enable_disable(iproc_i2c, false);

        return 0;
}

static int bcm_iproc_i2c_resume(struct device *dev)
{
        struct bcm_iproc_i2c_dev *iproc_i2c = dev_get_drvdata(dev);
        int ret;
        u32 val;

        /*
         * Power domain could have been shut off completely in system deep
         * sleep, so re-initialize the block here
         */
        ret = bcm_iproc_i2c_init(iproc_i2c);
        if (ret)
                return ret;

        /* configure to the desired bus speed */
        val = iproc_i2c_rd_reg(iproc_i2c, TIM_CFG_OFFSET);
        val &= ~BIT(TIM_CFG_MODE_400_SHIFT);
        val |= (iproc_i2c->bus_speed == 400000) << TIM_CFG_MODE_400_SHIFT;
        iproc_i2c_wr_reg(iproc_i2c, TIM_CFG_OFFSET, val);

        bcm_iproc_i2c_enable_disable(iproc_i2c, true);

        return 0;

}

static const struct dev_pm_ops bcm_iproc_i2c_pm_ops = {
        .suspend_late = &bcm_iproc_i2c_suspend,
        .resume_early = &bcm_iproc_i2c_resume
};

#define BCM_IPROC_I2C_PM_OPS (&bcm_iproc_i2c_pm_ops)
#else
#define BCM_IPROC_I2C_PM_OPS NULL
#endif /* CONFIG_PM_SLEEP */


static int bcm_iproc_i2c_reg_slave(struct i2c_client *slave)
{
        struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(slave->adapter);

        if (iproc_i2c->slave)
                return -EBUSY;

        if (slave->flags & I2C_CLIENT_TEN)
                return -EAFNOSUPPORT;

        iproc_i2c->slave = slave;
        bcm_iproc_i2c_slave_init(iproc_i2c, false);
        return 0;
}

static int bcm_iproc_i2c_unreg_slave(struct i2c_client *slave)
{
        u32 tmp;
        struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(slave->adapter);

        if (!iproc_i2c->slave)
                return -EINVAL;

        iproc_i2c->slave = NULL;

        /* disable all slave interrupts */
        tmp = iproc_i2c_rd_reg(iproc_i2c, IE_OFFSET);
        tmp &= ~(IE_S_ALL_INTERRUPT_MASK <<
                        IE_S_ALL_INTERRUPT_SHIFT);
        iproc_i2c_wr_reg(iproc_i2c, IE_OFFSET, tmp);

        /* Erase the slave address programmed */
        tmp = iproc_i2c_rd_reg(iproc_i2c, S_CFG_SMBUS_ADDR_OFFSET);
        tmp &= ~BIT(S_CFG_EN_NIC_SMB_ADDR3_SHIFT);
        iproc_i2c_wr_reg(iproc_i2c, S_CFG_SMBUS_ADDR_OFFSET, tmp);

        return 0;
}

static const struct of_device_id bcm_iproc_i2c_of_match[] = {
        {
                .compatible = "brcm,iproc-i2c",
                .data = (int *)IPROC_I2C,
        }, {
                .compatible = "brcm,iproc-nic-i2c",
                .data = (int *)IPROC_I2C_NIC,
        },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, bcm_iproc_i2c_of_match);

static struct platform_driver bcm_iproc_i2c_driver = {
        .driver = {
                .name = "bcm-iproc-i2c",
                .of_match_table = bcm_iproc_i2c_of_match,
                .pm = BCM_IPROC_I2C_PM_OPS,
        },
        .probe = bcm_iproc_i2c_probe,
        .remove = bcm_iproc_i2c_remove,
};
module_platform_driver(bcm_iproc_i2c_driver);

MODULE_AUTHOR("Ray Jui <rjui@broadcom.com>");
MODULE_DESCRIPTION("Broadcom iProc I2C Driver");
MODULE_LICENSE("GPL v2");