/*
 * Copyright (C) 2013 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/device.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/slab.h>

/* Hardware register offsets and field defintions */
#define CS_OFFSET                               0x00000020
#define CS_ACK_SHIFT                            3
#define CS_ACK_MASK                             0x00000008
#define CS_ACK_CMD_GEN_START                    0x00000000
#define CS_ACK_CMD_GEN_RESTART                  0x00000001
#define CS_CMD_SHIFT                            1
#define CS_CMD_CMD_NO_ACTION                    0x00000000
#define CS_CMD_CMD_START_RESTART                0x00000001
#define CS_CMD_CMD_STOP                         0x00000002
#define CS_EN_SHIFT                             0
#define CS_EN_CMD_ENABLE_BSC                    0x00000001

#define TIM_OFFSET                              0x00000024
#define TIM_PRESCALE_SHIFT                      6
#define TIM_P_SHIFT                             3
#define TIM_NO_DIV_SHIFT                        2
#define TIM_DIV_SHIFT                           0

#define DAT_OFFSET                              0x00000028

#define TOUT_OFFSET                             0x0000002c

#define TXFCR_OFFSET                            0x0000003c
#define TXFCR_FIFO_FLUSH_MASK                   0x00000080
#define TXFCR_FIFO_EN_MASK                      0x00000040

#define IER_OFFSET                              0x00000044
#define IER_READ_COMPLETE_INT_MASK              0x00000010
#define IER_I2C_INT_EN_MASK                     0x00000008
#define IER_FIFO_INT_EN_MASK                    0x00000002
#define IER_NOACK_EN_MASK                       0x00000001

#define ISR_OFFSET                              0x00000048
#define ISR_RESERVED_MASK                       0xffffff60
#define ISR_CMDBUSY_MASK                        0x00000080
#define ISR_READ_COMPLETE_MASK                  0x00000010
#define ISR_SES_DONE_MASK                       0x00000008
#define ISR_ERR_MASK                            0x00000004
#define ISR_TXFIFOEMPTY_MASK                    0x00000002
#define ISR_NOACK_MASK                          0x00000001

#define CLKEN_OFFSET                            0x0000004C
#define CLKEN_AUTOSENSE_OFF_MASK                0x00000080
#define CLKEN_M_SHIFT                           4
#define CLKEN_N_SHIFT                           1
#define CLKEN_CLKEN_MASK                        0x00000001

#define FIFO_STATUS_OFFSET                      0x00000054
#define FIFO_STATUS_RXFIFO_EMPTY_MASK           0x00000004
#define FIFO_STATUS_TXFIFO_EMPTY_MASK           0x00000010

#define HSTIM_OFFSET                            0x00000058
#define HSTIM_HS_MODE_MASK                      0x00008000
#define HSTIM_HS_HOLD_SHIFT                     10
#define HSTIM_HS_HIGH_PHASE_SHIFT               5
#define HSTIM_HS_SETUP_SHIFT                    0

#define PADCTL_OFFSET                           0x0000005c
#define PADCTL_PAD_OUT_EN_MASK                  0x00000004

#define RXFCR_OFFSET                            0x00000068
#define RXFCR_NACK_EN_SHIFT                     7
#define RXFCR_READ_COUNT_SHIFT                  0
#define RXFIFORDOUT_OFFSET                      0x0000006c

/* Locally used constants */
#define MAX_RX_FIFO_SIZE                64U /* bytes */
#define MAX_TX_FIFO_SIZE                64U /* bytes */

#define STD_EXT_CLK_FREQ                13000000UL
#define HS_EXT_CLK_FREQ                 104000000UL

#define MASTERCODE                      0x08 /* Mastercodes are 0000_1xxxb */

#define I2C_TIMEOUT                     100 /* msecs */

/* Operations that can be commanded to the controller */
enum bcm_kona_cmd_t {
        BCM_CMD_NOACTION = 0,
        BCM_CMD_START,
        BCM_CMD_RESTART,
        BCM_CMD_STOP,
};

enum bus_speed_index {
        BCM_SPD_100K = 0,
        BCM_SPD_400K,
        BCM_SPD_1MHZ,
};

enum hs_bus_speed_index {
        BCM_SPD_3P4MHZ = 0,
};

/* Internal divider settings for standard mode, fast mode and fast mode plus */
struct bus_speed_cfg {
        uint8_t time_m;         /* Number of cycles for setup time */
        uint8_t time_n;         /* Number of cycles for hold time */
        uint8_t prescale;       /* Prescale divider */
        uint8_t time_p;         /* Timing coefficient */
        uint8_t no_div;         /* Disable clock divider */
        uint8_t time_div;       /* Post-prescale divider */
};

/* Internal divider settings for high-speed mode */
struct hs_bus_speed_cfg {
        uint8_t hs_hold;        /* Number of clock cycles SCL stays low until
                                   the end of bit period */
        uint8_t hs_high_phase;  /* Number of clock cycles SCL stays high
                                   before it falls */
        uint8_t hs_setup;       /* Number of clock cycles SCL stays low
                                   before it rises  */
        uint8_t prescale;       /* Prescale divider */
        uint8_t time_p;         /* Timing coefficient */
        uint8_t no_div;         /* Disable clock divider */
        uint8_t time_div;       /* Post-prescale divider */
};

static const struct bus_speed_cfg std_cfg_table[] = {
        [BCM_SPD_100K] = {0x01, 0x01, 0x03, 0x06, 0x00, 0x02},
        [BCM_SPD_400K] = {0x05, 0x01, 0x03, 0x05, 0x01, 0x02},
        [BCM_SPD_1MHZ] = {0x01, 0x01, 0x03, 0x01, 0x01, 0x03},
};

static const struct hs_bus_speed_cfg hs_cfg_table[] = {
        [BCM_SPD_3P4MHZ] = {0x01, 0x08, 0x14, 0x00, 0x06, 0x01, 0x00},
};

struct bcm_kona_i2c_dev {
        struct device *device;

        void __iomem *base;
        int irq;
        struct clk *external_clk;

        struct i2c_adapter adapter;

        struct completion done;

        const struct bus_speed_cfg *std_cfg;
        const struct hs_bus_speed_cfg *hs_cfg;
};

static void bcm_kona_i2c_send_cmd_to_ctrl(struct bcm_kona_i2c_dev *dev,
                                          enum bcm_kona_cmd_t cmd)
{
        dev_dbg(dev->device, "%s, %d\n", __func__, cmd);

        switch (cmd) {
        case BCM_CMD_NOACTION:
                writel((CS_CMD_CMD_NO_ACTION << CS_CMD_SHIFT) |
                       (CS_EN_CMD_ENABLE_BSC << CS_EN_SHIFT),
                       dev->base + CS_OFFSET);
                break;

        case BCM_CMD_START:
                writel((CS_ACK_CMD_GEN_START << CS_ACK_SHIFT) |
                       (CS_CMD_CMD_START_RESTART << CS_CMD_SHIFT) |
                       (CS_EN_CMD_ENABLE_BSC << CS_EN_SHIFT),
                       dev->base + CS_OFFSET);
                break;

        case BCM_CMD_RESTART:
                writel((CS_ACK_CMD_GEN_RESTART << CS_ACK_SHIFT) |
                       (CS_CMD_CMD_START_RESTART << CS_CMD_SHIFT) |
                       (CS_EN_CMD_ENABLE_BSC << CS_EN_SHIFT),
                       dev->base + CS_OFFSET);
                break;

        case BCM_CMD_STOP:
                writel((CS_CMD_CMD_STOP << CS_CMD_SHIFT) |
                       (CS_EN_CMD_ENABLE_BSC << CS_EN_SHIFT),
                       dev->base + CS_OFFSET);
                break;

        default:
                dev_err(dev->device, "Unknown command %d\n", cmd);
        }
}

static void bcm_kona_i2c_enable_clock(struct bcm_kona_i2c_dev *dev)
{
        writel(readl(dev->base + CLKEN_OFFSET) | CLKEN_CLKEN_MASK,
               dev->base + CLKEN_OFFSET);
}

static void bcm_kona_i2c_disable_clock(struct bcm_kona_i2c_dev *dev)
{
        writel(readl(dev->base + CLKEN_OFFSET) & ~CLKEN_CLKEN_MASK,
               dev->base + CLKEN_OFFSET);
}

static irqreturn_t bcm_kona_i2c_isr(int irq, void *devid)
{
        struct bcm_kona_i2c_dev *dev = devid;
        uint32_t status = readl(dev->base + ISR_OFFSET);

        if ((status & ~ISR_RESERVED_MASK) == 0)
                return IRQ_NONE;

        /* Must flush the TX FIFO when NAK detected */
        if (status & ISR_NOACK_MASK)
                writel(TXFCR_FIFO_FLUSH_MASK | TXFCR_FIFO_EN_MASK,
                       dev->base + TXFCR_OFFSET);

        writel(status & ~ISR_RESERVED_MASK, dev->base + ISR_OFFSET);
        complete_all(&dev->done);

        return IRQ_HANDLED;
}

/* Wait for ISR_CMDBUSY_MASK to go low before writing to CS, DAT, or RCD */
static int bcm_kona_i2c_wait_if_busy(struct bcm_kona_i2c_dev *dev)
{
        unsigned long timeout = jiffies + msecs_to_jiffies(I2C_TIMEOUT);

        while (readl(dev->base + ISR_OFFSET) & ISR_CMDBUSY_MASK)
                if (time_after(jiffies, timeout)) {
                        dev_err(dev->device, "CMDBUSY timeout\n");
                        return -ETIMEDOUT;
                }

        return 0;
}

/* Send command to I2C bus */
static int bcm_kona_send_i2c_cmd(struct bcm_kona_i2c_dev *dev,
                                 enum bcm_kona_cmd_t cmd)
{
        int rc;
        unsigned long time_left = msecs_to_jiffies(I2C_TIMEOUT);

        /* Make sure the hardware is ready */
        rc = bcm_kona_i2c_wait_if_busy(dev);
        if (rc < 0)
                return rc;

        /* Unmask the session done interrupt */
        writel(IER_I2C_INT_EN_MASK, dev->base + IER_OFFSET);

        /* Mark as incomplete before sending the command */
        reinit_completion(&dev->done);

        /* Send the command */
        bcm_kona_i2c_send_cmd_to_ctrl(dev, cmd);

        /* Wait for transaction to finish or timeout */
        time_left = wait_for_completion_timeout(&dev->done, time_left);

        /* Mask all interrupts */
        writel(0, dev->base + IER_OFFSET);

        if (!time_left) {
                dev_err(dev->device, "controller timed out\n");
                rc = -ETIMEDOUT;
        }

        /* Clear command */
        bcm_kona_i2c_send_cmd_to_ctrl(dev, BCM_CMD_NOACTION);

        return rc;
}

/* Read a single RX FIFO worth of data from the i2c bus */
static int bcm_kona_i2c_read_fifo_single(struct bcm_kona_i2c_dev *dev,
                                         uint8_t *buf, unsigned int len,
                                         unsigned int last_byte_nak)
{
        unsigned long time_left = msecs_to_jiffies(I2C_TIMEOUT);

        /* Mark as incomplete before starting the RX FIFO */
        reinit_completion(&dev->done);

        /* Unmask the read complete interrupt */
        writel(IER_READ_COMPLETE_INT_MASK, dev->base + IER_OFFSET);

        /* Start the RX FIFO */
        writel((last_byte_nak << RXFCR_NACK_EN_SHIFT) |
               (len << RXFCR_READ_COUNT_SHIFT),
                dev->base + RXFCR_OFFSET);

        /* Wait for FIFO read to complete */
        time_left = wait_for_completion_timeout(&dev->done, time_left);

        /* Mask all interrupts */
        writel(0, dev->base + IER_OFFSET);

        if (!time_left) {
                dev_err(dev->device, "RX FIFO time out\n");
                return -EREMOTEIO;
        }

        /* Read data from FIFO */
        for (; len > 0; len--, buf++)
                *buf = readl(dev->base + RXFIFORDOUT_OFFSET);

        return 0;
}

/* Read any amount of data using the RX FIFO from the i2c bus */
static int bcm_kona_i2c_read_fifo(struct bcm_kona_i2c_dev *dev,
                                  struct i2c_msg *msg)
{
        unsigned int bytes_to_read = MAX_RX_FIFO_SIZE;
        unsigned int last_byte_nak = 0;
        unsigned int bytes_read = 0;
        int rc;

        uint8_t *tmp_buf = msg->buf;

        while (bytes_read < msg->len) {
                if (msg->len - bytes_read <= MAX_RX_FIFO_SIZE) {
                        last_byte_nak = 1; /* NAK last byte of transfer */
                        bytes_to_read = msg->len - bytes_read;
                }

                rc = bcm_kona_i2c_read_fifo_single(dev, tmp_buf, bytes_to_read,
                                                   last_byte_nak);
                if (rc < 0)
                        return -EREMOTEIO;

                bytes_read += bytes_to_read;
                tmp_buf += bytes_to_read;
        }

        return 0;
}

/* Write a single byte of data to the i2c bus */
static int bcm_kona_i2c_write_byte(struct bcm_kona_i2c_dev *dev, uint8_t data,
                                   unsigned int nak_expected)
{
        int rc;
        unsigned long time_left = msecs_to_jiffies(I2C_TIMEOUT);
        unsigned int nak_received;

        /* Make sure the hardware is ready */
        rc = bcm_kona_i2c_wait_if_busy(dev);
        if (rc < 0)
                return rc;

        /* Clear pending session done interrupt */
        writel(ISR_SES_DONE_MASK, dev->base + ISR_OFFSET);

        /* Unmask the session done interrupt */
        writel(IER_I2C_INT_EN_MASK, dev->base + IER_OFFSET);

        /* Mark as incomplete before sending the data */
        reinit_completion(&dev->done);

        /* Send one byte of data */
        writel(data, dev->base + DAT_OFFSET);

        /* Wait for byte to be written */
        time_left = wait_for_completion_timeout(&dev->done, time_left);

        /* Mask all interrupts */
        writel(0, dev->base + IER_OFFSET);

        if (!time_left) {
                dev_dbg(dev->device, "controller timed out\n");
                return -ETIMEDOUT;
        }

        nak_received = readl(dev->base + CS_OFFSET) & CS_ACK_MASK ? 1 : 0;

        if (nak_received ^ nak_expected) {
                dev_dbg(dev->device, "unexpected NAK/ACK\n");
                return -EREMOTEIO;
        }

        return 0;
}

/* Write a single TX FIFO worth of data to the i2c bus */
static int bcm_kona_i2c_write_fifo_single(struct bcm_kona_i2c_dev *dev,
                                          uint8_t *buf, unsigned int len)
{
        int k;
        unsigned long time_left = msecs_to_jiffies(I2C_TIMEOUT);
        unsigned int fifo_status;

        /* Mark as incomplete before sending data to the TX FIFO */
        reinit_completion(&dev->done);

        /* Unmask the fifo empty and nak interrupt */
        writel(IER_FIFO_INT_EN_MASK | IER_NOACK_EN_MASK,
               dev->base + IER_OFFSET);

        /* Disable IRQ to load a FIFO worth of data without interruption */
        disable_irq(dev->irq);

        /* Write data into FIFO */
        for (k = 0; k < len; k++)
                writel(buf[k], (dev->base + DAT_OFFSET));

        /* Enable IRQ now that data has been loaded */
        enable_irq(dev->irq);

        /* Wait for FIFO to empty */
        do {
                time_left = wait_for_completion_timeout(&dev->done, time_left);
                fifo_status = readl(dev->base + FIFO_STATUS_OFFSET);
        } while (time_left && !(fifo_status & FIFO_STATUS_TXFIFO_EMPTY_MASK));

        /* Mask all interrupts */
        writel(0, dev->base + IER_OFFSET);

        /* Check if there was a NAK */
        if (readl(dev->base + CS_OFFSET) & CS_ACK_MASK) {
                dev_err(dev->device, "unexpected NAK\n");
                return -EREMOTEIO;
        }

        /* Check if a timeout occured */
        if (!time_left) {
                dev_err(dev->device, "completion timed out\n");
                return -EREMOTEIO;
        }

        return 0;
}


/* Write any amount of data using TX FIFO to the i2c bus */
static int bcm_kona_i2c_write_fifo(struct bcm_kona_i2c_dev *dev,
                                   struct i2c_msg *msg)
{
        unsigned int bytes_to_write = MAX_TX_FIFO_SIZE;
        unsigned int bytes_written = 0;
        int rc;

        uint8_t *tmp_buf = msg->buf;

        while (bytes_written < msg->len) {
                if (msg->len - bytes_written <= MAX_TX_FIFO_SIZE)
                        bytes_to_write = msg->len - bytes_written;

                rc = bcm_kona_i2c_write_fifo_single(dev, tmp_buf,
                                                    bytes_to_write);
                if (rc < 0)
                        return -EREMOTEIO;

                bytes_written += bytes_to_write;
                tmp_buf += bytes_to_write;
        }

        return 0;
}

/* Send i2c address */
static int bcm_kona_i2c_do_addr(struct bcm_kona_i2c_dev *dev,
                                     struct i2c_msg *msg)
{
        unsigned char addr;

        if (msg->flags & I2C_M_TEN) {
                /* First byte is 11110XX0 where XX is upper 2 bits */
                addr = 0xF0 | ((msg->addr & 0x300) >> 7);
                if (bcm_kona_i2c_write_byte(dev, addr, 0) < 0)
                        return -EREMOTEIO;

                /* Second byte is the remaining 8 bits */
                addr = msg->addr & 0xFF;
                if (bcm_kona_i2c_write_byte(dev, addr, 0) < 0)
                        return -EREMOTEIO;

                if (msg->flags & I2C_M_RD) {
                        /* For read, send restart command */
                        if (bcm_kona_send_i2c_cmd(dev, BCM_CMD_RESTART) < 0)
                                return -EREMOTEIO;

                        /* Then re-send the first byte with the read bit set */
                        addr = 0xF0 | ((msg->addr & 0x300) >> 7) | 0x01;
                        if (bcm_kona_i2c_write_byte(dev, addr, 0) < 0)
                                return -EREMOTEIO;
                }
        } else {
                addr = msg->addr << 1;

                if (msg->flags & I2C_M_RD)
                        addr |= 1;

                if (bcm_kona_i2c_write_byte(dev, addr, 0) < 0)
                        return -EREMOTEIO;
        }

        return 0;
}

static void bcm_kona_i2c_enable_autosense(struct bcm_kona_i2c_dev *dev)
{
        writel(readl(dev->base + CLKEN_OFFSET) & ~CLKEN_AUTOSENSE_OFF_MASK,
               dev->base + CLKEN_OFFSET);
}

static void bcm_kona_i2c_config_timing(struct bcm_kona_i2c_dev *dev)
{
        writel(readl(dev->base + HSTIM_OFFSET) & ~HSTIM_HS_MODE_MASK,
               dev->base + HSTIM_OFFSET);

        writel((dev->std_cfg->prescale << TIM_PRESCALE_SHIFT) |
               (dev->std_cfg->time_p << TIM_P_SHIFT) |
               (dev->std_cfg->no_div << TIM_NO_DIV_SHIFT) |
               (dev->std_cfg->time_div  << TIM_DIV_SHIFT),
               dev->base + TIM_OFFSET);

        writel((dev->std_cfg->time_m << CLKEN_M_SHIFT) |
               (dev->std_cfg->time_n << CLKEN_N_SHIFT) |
               CLKEN_CLKEN_MASK,
               dev->base + CLKEN_OFFSET);
}

static void bcm_kona_i2c_config_timing_hs(struct bcm_kona_i2c_dev *dev)
{
        writel((dev->hs_cfg->prescale << TIM_PRESCALE_SHIFT) |
               (dev->hs_cfg->time_p << TIM_P_SHIFT) |
               (dev->hs_cfg->no_div << TIM_NO_DIV_SHIFT) |
               (dev->hs_cfg->time_div << TIM_DIV_SHIFT),
               dev->base + TIM_OFFSET);

        writel((dev->hs_cfg->hs_hold << HSTIM_HS_HOLD_SHIFT) |
               (dev->hs_cfg->hs_high_phase << HSTIM_HS_HIGH_PHASE_SHIFT) |
               (dev->hs_cfg->hs_setup << HSTIM_HS_SETUP_SHIFT),
               dev->base + HSTIM_OFFSET);

        writel(readl(dev->base + HSTIM_OFFSET) | HSTIM_HS_MODE_MASK,
               dev->base + HSTIM_OFFSET);
}

static int bcm_kona_i2c_switch_to_hs(struct bcm_kona_i2c_dev *dev)
{
        int rc;

        /* Send mastercode at standard speed */
        rc = bcm_kona_i2c_write_byte(dev, MASTERCODE, 1);
        if (rc < 0) {
                pr_err("High speed handshake failed\n");
                return rc;
        }

        /* Configure external clock to higher frequency */
        rc = clk_set_rate(dev->external_clk, HS_EXT_CLK_FREQ);
        if (rc) {
                dev_err(dev->device, "%s: clk_set_rate returned %d\n",
                        __func__, rc);
                return rc;
        }

        /* Reconfigure internal dividers */
        bcm_kona_i2c_config_timing_hs(dev);

        /* Send a restart command */
        rc = bcm_kona_send_i2c_cmd(dev, BCM_CMD_RESTART);
        if (rc < 0)
                dev_err(dev->device, "High speed restart command failed\n");

        return rc;
}

static int bcm_kona_i2c_switch_to_std(struct bcm_kona_i2c_dev *dev)
{
        int rc;

        /* Reconfigure internal dividers */
        bcm_kona_i2c_config_timing(dev);

        /* Configure external clock to lower frequency */
        rc = clk_set_rate(dev->external_clk, STD_EXT_CLK_FREQ);
        if (rc) {
                dev_err(dev->device, "%s: clk_set_rate returned %d\n",
                        __func__, rc);
        }

        return rc;
}

/* Master transfer function */
static int bcm_kona_i2c_xfer(struct i2c_adapter *adapter,
                             struct i2c_msg msgs[], int num)
{
        struct bcm_kona_i2c_dev *dev = i2c_get_adapdata(adapter);
        struct i2c_msg *pmsg;
        int rc = 0;
        int i;

        rc = clk_prepare_enable(dev->external_clk);
        if (rc) {
                dev_err(dev->device, "%s: peri clock enable failed. err %d\n",
                        __func__, rc);
                return rc;
        }

        /* Enable pad output */
        writel(0, dev->base + PADCTL_OFFSET);

        /* Enable internal clocks */
        bcm_kona_i2c_enable_clock(dev);

        /* Send start command */
        rc = bcm_kona_send_i2c_cmd(dev, BCM_CMD_START);
        if (rc < 0) {
                dev_err(dev->device, "Start command failed rc = %d\n", rc);
                goto xfer_disable_pad;
        }

        /* Switch to high speed if applicable */
        if (dev->hs_cfg) {
                rc = bcm_kona_i2c_switch_to_hs(dev);
                if (rc < 0)
                        goto xfer_send_stop;
        }

        /* Loop through all messages */
        for (i = 0; i < num; i++) {
                pmsg = &msgs[i];

                /* Send restart for subsequent messages */
                if ((i != 0) && ((pmsg->flags & I2C_M_NOSTART) == 0)) {
                        rc = bcm_kona_send_i2c_cmd(dev, BCM_CMD_RESTART);
                        if (rc < 0) {
                                dev_err(dev->device,
                                        "restart cmd failed rc = %d\n", rc);
                                        goto xfer_send_stop;
                        }
                }

                /* Send slave address */
                if (!(pmsg->flags & I2C_M_NOSTART)) {
                        rc = bcm_kona_i2c_do_addr(dev, pmsg);
                        if (rc < 0) {
                                dev_err(dev->device,
                                        "NAK from addr %2.2x msg#%d rc = %d\n",
                                        pmsg->addr, i, rc);
                                goto xfer_send_stop;
                        }
                }

                /* Perform data transfer */
                if (pmsg->flags & I2C_M_RD) {
                        rc = bcm_kona_i2c_read_fifo(dev, pmsg);
                        if (rc < 0) {
                                dev_err(dev->device, "read failure\n");
                                goto xfer_send_stop;
                        }
                } else {
                        rc = bcm_kona_i2c_write_fifo(dev, pmsg);
                        if (rc < 0) {
                                dev_err(dev->device, "write failure");
                                goto xfer_send_stop;
                        }
                }
        }

        rc = num;

xfer_send_stop:
        /* Send a STOP command */
        bcm_kona_send_i2c_cmd(dev, BCM_CMD_STOP);

        /* Return from high speed if applicable */
        if (dev->hs_cfg) {
                int hs_rc = bcm_kona_i2c_switch_to_std(dev);

                if (hs_rc)
                        rc = hs_rc;
        }

xfer_disable_pad:
        /* Disable pad output */
        writel(PADCTL_PAD_OUT_EN_MASK, dev->base + PADCTL_OFFSET);

        /* Stop internal clock */
        bcm_kona_i2c_disable_clock(dev);

        clk_disable_unprepare(dev->external_clk);

        return rc;
}

static uint32_t bcm_kona_i2c_functionality(struct i2c_adapter *adap)
{
        return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR |
            I2C_FUNC_NOSTART;
}

static const struct i2c_algorithm bcm_algo = {
        .master_xfer = bcm_kona_i2c_xfer,
        .functionality = bcm_kona_i2c_functionality,
};

static int bcm_kona_i2c_assign_bus_speed(struct bcm_kona_i2c_dev *dev)
{
        unsigned int bus_speed;
        int ret = of_property_read_u32(dev->device->of_node, "clock-frequency",
                                       &bus_speed);
        if (ret < 0) {
                dev_err(dev->device, "missing clock-frequency property\n");
                return -ENODEV;
        }

        switch (bus_speed) {
        case 100000:
                dev->std_cfg = &std_cfg_table[BCM_SPD_100K];
                break;
        case 400000:
                dev->std_cfg = &std_cfg_table[BCM_SPD_400K];
                break;
        case 1000000:
                dev->std_cfg = &std_cfg_table[BCM_SPD_1MHZ];
                break;
        case 3400000:
                /* Send mastercode at 100k */
                dev->std_cfg = &std_cfg_table[BCM_SPD_100K];
                dev->hs_cfg = &hs_cfg_table[BCM_SPD_3P4MHZ];
                break;
        default:
                pr_err("%d hz bus speed not supported\n", bus_speed);
                pr_err("Valid speeds are 100khz, 400khz, 1mhz, and 3.4mhz\n");
                return -EINVAL;
        }

        return 0;
}

static int bcm_kona_i2c_probe(struct platform_device *pdev)
{
        int rc = 0;
        struct bcm_kona_i2c_dev *dev;
        struct i2c_adapter *adap;
        struct resource *iomem;

        /* Allocate memory for private data structure */
        dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
        if (!dev)
                return -ENOMEM;

        platform_set_drvdata(pdev, dev);
        dev->device = &pdev->dev;
        init_completion(&dev->done);

        /* Map hardware registers */
        iomem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        dev->base = devm_ioremap_resource(dev->device, iomem);
        if (IS_ERR(dev->base))
                return -ENOMEM;

        /* Get and enable external clock */
        dev->external_clk = devm_clk_get(dev->device, NULL);
        if (IS_ERR(dev->external_clk)) {
                dev_err(dev->device, "couldn't get clock\n");
                return -ENODEV;
        }

        rc = clk_set_rate(dev->external_clk, STD_EXT_CLK_FREQ);
        if (rc) {
                dev_err(dev->device, "%s: clk_set_rate returned %d\n",
                        __func__, rc);
                return rc;
        }

        rc = clk_prepare_enable(dev->external_clk);
        if (rc) {
                dev_err(dev->device, "couldn't enable clock\n");
                return rc;
        }

        /* Parse bus speed */
        rc = bcm_kona_i2c_assign_bus_speed(dev);
        if (rc)
                goto probe_disable_clk;

        /* Enable internal clocks */
        bcm_kona_i2c_enable_clock(dev);

        /* Configure internal dividers */
        bcm_kona_i2c_config_timing(dev);

        /* Disable timeout */
        writel(0, dev->base + TOUT_OFFSET);

        /* Enable autosense */
        bcm_kona_i2c_enable_autosense(dev);

        /* Enable TX FIFO */
        writel(TXFCR_FIFO_FLUSH_MASK | TXFCR_FIFO_EN_MASK,
               dev->base + TXFCR_OFFSET);

        /* Mask all interrupts */
        writel(0, dev->base + IER_OFFSET);

        /* Clear all pending interrupts */
        writel(ISR_CMDBUSY_MASK |
               ISR_READ_COMPLETE_MASK |
               ISR_SES_DONE_MASK |
               ISR_ERR_MASK |
               ISR_TXFIFOEMPTY_MASK |
               ISR_NOACK_MASK,
               dev->base + ISR_OFFSET);

        /* Get the interrupt number */
        dev->irq = platform_get_irq(pdev, 0);
        if (dev->irq < 0) {
                dev_err(dev->device, "no irq resource\n");
                rc = -ENODEV;
                goto probe_disable_clk;
        }

        /* register the ISR handler */
        rc = devm_request_irq(&pdev->dev, dev->irq, bcm_kona_i2c_isr,
                              IRQF_SHARED, pdev->name, dev);
        if (rc) {
                dev_err(dev->device, "failed to request irq %i\n", dev->irq);
                goto probe_disable_clk;
        }

        /* Enable the controller but leave it idle */
        bcm_kona_i2c_send_cmd_to_ctrl(dev, BCM_CMD_NOACTION);

        /* Disable pad output */
        writel(PADCTL_PAD_OUT_EN_MASK, dev->base + PADCTL_OFFSET);

        /* Disable internal clock */
        bcm_kona_i2c_disable_clock(dev);

        /* Disable external clock */
        clk_disable_unprepare(dev->external_clk);

        /* Add the i2c adapter */
        adap = &dev->adapter;
        i2c_set_adapdata(adap, dev);
        adap->owner = THIS_MODULE;
        strlcpy(adap->name, "Broadcom I2C adapter", sizeof(adap->name));
        adap->algo = &bcm_algo;
        adap->dev.parent = &pdev->dev;
        adap->dev.of_node = pdev->dev.of_node;

        rc = i2c_add_adapter(adap);
        if (rc) {
                dev_err(dev->device, "failed to add adapter\n");
                return rc;
        }

        dev_info(dev->device, "device registered successfully\n");

        return 0;

probe_disable_clk:
        bcm_kona_i2c_disable_clock(dev);
        clk_disable_unprepare(dev->external_clk);

        return rc;
}

static int bcm_kona_i2c_remove(struct platform_device *pdev)
{
        struct bcm_kona_i2c_dev *dev = platform_get_drvdata(pdev);

        i2c_del_adapter(&dev->adapter);

        return 0;
}

static const struct of_device_id bcm_kona_i2c_of_match[] = {
        {.compatible = "brcm,kona-i2c",},
        {},
};
MODULE_DEVICE_TABLE(of, bcm_kona_i2c_of_match);

static struct platform_driver bcm_kona_i2c_driver = {
        .driver = {
                   .name = "bcm-kona-i2c",
                   .of_match_table = bcm_kona_i2c_of_match,
                   },
        .probe = bcm_kona_i2c_probe,
        .remove = bcm_kona_i2c_remove,
};
module_platform_driver(bcm_kona_i2c_driver);

MODULE_AUTHOR("Tim Kryger <tkryger@broadcom.com>");
MODULE_DESCRIPTION("Broadcom Kona I2C Driver");
MODULE_LICENSE("GPL v2");