/*
 * Copyright (C) 2015 Masahiro Yamada <yamada.masahiro@socionext.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/clk.h>
#include <linux/i2c.h>
#include <linux/iopoll.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/platform_device.h>

#define UNIPHIER_FI2C_CR        0x00    /* control register */
#define     UNIPHIER_FI2C_CR_MST        BIT(3)  /* master mode */
#define     UNIPHIER_FI2C_CR_STA        BIT(2)  /* start condition */
#define     UNIPHIER_FI2C_CR_STO        BIT(1)  /* stop condition */
#define     UNIPHIER_FI2C_CR_NACK       BIT(0)  /* do not return ACK */
#define UNIPHIER_FI2C_DTTX      0x04    /* TX FIFO */
#define     UNIPHIER_FI2C_DTTX_CMD      BIT(8)  /* send command (slave addr) */
#define     UNIPHIER_FI2C_DTTX_RD       BIT(0)  /* read transaction */
#define UNIPHIER_FI2C_DTRX      0x04    /* RX FIFO */
#define UNIPHIER_FI2C_SLAD      0x0c    /* slave address */
#define UNIPHIER_FI2C_CYC       0x10    /* clock cycle control */
#define UNIPHIER_FI2C_LCTL      0x14    /* clock low period control */
#define UNIPHIER_FI2C_SSUT      0x18    /* restart/stop setup time control */
#define UNIPHIER_FI2C_DSUT      0x1c    /* data setup time control */
#define UNIPHIER_FI2C_INT       0x20    /* interrupt status */
#define UNIPHIER_FI2C_IE        0x24    /* interrupt enable */
#define UNIPHIER_FI2C_IC        0x28    /* interrupt clear */
#define     UNIPHIER_FI2C_INT_TE        BIT(9)  /* TX FIFO empty */
#define     UNIPHIER_FI2C_INT_RF        BIT(8)  /* RX FIFO full */
#define     UNIPHIER_FI2C_INT_TC        BIT(7)  /* send complete (STOP) */
#define     UNIPHIER_FI2C_INT_RC        BIT(6)  /* receive complete (STOP) */
#define     UNIPHIER_FI2C_INT_TB        BIT(5)  /* sent specified bytes */
#define     UNIPHIER_FI2C_INT_RB        BIT(4)  /* received specified bytes */
#define     UNIPHIER_FI2C_INT_NA        BIT(2)  /* no ACK */
#define     UNIPHIER_FI2C_INT_AL        BIT(1)  /* arbitration lost */
#define UNIPHIER_FI2C_SR        0x2c    /* status register */
#define     UNIPHIER_FI2C_SR_DB         BIT(12) /* device busy */
#define     UNIPHIER_FI2C_SR_STS        BIT(11) /* stop condition detected */
#define     UNIPHIER_FI2C_SR_BB         BIT(8)  /* bus busy */
#define     UNIPHIER_FI2C_SR_RFF        BIT(3)  /* RX FIFO full */
#define     UNIPHIER_FI2C_SR_RNE        BIT(2)  /* RX FIFO not empty */
#define     UNIPHIER_FI2C_SR_TNF        BIT(1)  /* TX FIFO not full */
#define     UNIPHIER_FI2C_SR_TFE        BIT(0)  /* TX FIFO empty */
#define UNIPHIER_FI2C_RST       0x34    /* reset control */
#define     UNIPHIER_FI2C_RST_TBRST     BIT(2)  /* clear TX FIFO */
#define     UNIPHIER_FI2C_RST_RBRST     BIT(1)  /* clear RX FIFO */
#define     UNIPHIER_FI2C_RST_RST       BIT(0)  /* forcible bus reset */
#define UNIPHIER_FI2C_BM        0x38    /* bus monitor */
#define     UNIPHIER_FI2C_BM_SDAO       BIT(3)  /* output for SDA line */
#define     UNIPHIER_FI2C_BM_SDAS       BIT(2)  /* readback of SDA line */
#define     UNIPHIER_FI2C_BM_SCLO       BIT(1)  /* output for SCL line */
#define     UNIPHIER_FI2C_BM_SCLS       BIT(0)  /* readback of SCL line */
#define UNIPHIER_FI2C_NOISE     0x3c    /* noise filter control */
#define UNIPHIER_FI2C_TBC       0x40    /* TX byte count setting */
#define UNIPHIER_FI2C_RBC       0x44    /* RX byte count setting */
#define UNIPHIER_FI2C_TBCM      0x48    /* TX byte count monitor */
#define UNIPHIER_FI2C_RBCM      0x4c    /* RX byte count monitor */
#define UNIPHIER_FI2C_BRST      0x50    /* bus reset */
#define     UNIPHIER_FI2C_BRST_FOEN     BIT(1)  /* normal operation */
#define     UNIPHIER_FI2C_BRST_RSCL     BIT(0)  /* release SCL */

#define UNIPHIER_FI2C_INT_FAULTS        \
                                (UNIPHIER_FI2C_INT_NA | UNIPHIER_FI2C_INT_AL)
#define UNIPHIER_FI2C_INT_STOP          \
                                (UNIPHIER_FI2C_INT_TC | UNIPHIER_FI2C_INT_RC)

#define UNIPHIER_FI2C_RD                BIT(0)
#define UNIPHIER_FI2C_STOP              BIT(1)
#define UNIPHIER_FI2C_MANUAL_NACK       BIT(2)
#define UNIPHIER_FI2C_BYTE_WISE         BIT(3)
#define UNIPHIER_FI2C_DEFER_STOP_COMP   BIT(4)

#define UNIPHIER_FI2C_DEFAULT_SPEED     100000
#define UNIPHIER_FI2C_MAX_SPEED         400000
#define UNIPHIER_FI2C_FIFO_SIZE         8

struct uniphier_fi2c_priv {
        struct completion comp;
        struct i2c_adapter adap;
        void __iomem *membase;
        struct clk *clk;
        unsigned int len;
        u8 *buf;
        u32 enabled_irqs;
        int error;
        unsigned int flags;
        unsigned int busy_cnt;
        unsigned int clk_cycle;
        spinlock_t lock;        /* IRQ synchronization */
};

static void uniphier_fi2c_fill_txfifo(struct uniphier_fi2c_priv *priv,
                                      bool first)
{
        int fifo_space = UNIPHIER_FI2C_FIFO_SIZE;

        /*
         * TX-FIFO stores slave address in it for the first access.
         * Decrement the counter.
         */
        if (first)
                fifo_space--;

        while (priv->len) {
                if (fifo_space-- <= 0)
                        break;

                dev_dbg(&priv->adap.dev, "write data: %02x\n", *priv->buf);
                writel(*priv->buf++, priv->membase + UNIPHIER_FI2C_DTTX);
                priv->len--;
        }
}

static void uniphier_fi2c_drain_rxfifo(struct uniphier_fi2c_priv *priv)
{
        int fifo_left = priv->flags & UNIPHIER_FI2C_BYTE_WISE ?
                                                1 : UNIPHIER_FI2C_FIFO_SIZE;

        while (priv->len) {
                if (fifo_left-- <= 0)
                        break;

                *priv->buf++ = readl(priv->membase + UNIPHIER_FI2C_DTRX);
                dev_dbg(&priv->adap.dev, "read data: %02x\n", priv->buf[-1]);
                priv->len--;
        }
}

static void uniphier_fi2c_set_irqs(struct uniphier_fi2c_priv *priv)
{
        writel(priv->enabled_irqs, priv->membase + UNIPHIER_FI2C_IE);
}

static void uniphier_fi2c_clear_irqs(struct uniphier_fi2c_priv *priv,
                                     u32 mask)
{
        writel(mask, priv->membase + UNIPHIER_FI2C_IC);
}

static void uniphier_fi2c_stop(struct uniphier_fi2c_priv *priv)
{
        dev_dbg(&priv->adap.dev, "stop condition\n");

        priv->enabled_irqs |= UNIPHIER_FI2C_INT_STOP;
        uniphier_fi2c_set_irqs(priv);
        writel(UNIPHIER_FI2C_CR_MST | UNIPHIER_FI2C_CR_STO,
               priv->membase + UNIPHIER_FI2C_CR);
}

static irqreturn_t uniphier_fi2c_interrupt(int irq, void *dev_id)
{
        struct uniphier_fi2c_priv *priv = dev_id;
        u32 irq_status;

        spin_lock(&priv->lock);

        irq_status = readl(priv->membase + UNIPHIER_FI2C_INT);
        irq_status &= priv->enabled_irqs;

        dev_dbg(&priv->adap.dev,
                "interrupt: enabled_irqs=%04x, irq_status=%04x\n",
                priv->enabled_irqs, irq_status);

        if (irq_status & UNIPHIER_FI2C_INT_STOP)
                goto complete;

        if (unlikely(irq_status & UNIPHIER_FI2C_INT_AL)) {
                dev_dbg(&priv->adap.dev, "arbitration lost\n");
                priv->error = -EAGAIN;
                goto complete;
        }

        if (unlikely(irq_status & UNIPHIER_FI2C_INT_NA)) {
                dev_dbg(&priv->adap.dev, "could not get ACK\n");
                priv->error = -ENXIO;
                if (priv->flags & UNIPHIER_FI2C_RD) {
                        /*
                         * work around a hardware bug:
                         * The receive-completed interrupt is never set even if
                         * STOP condition is detected after the address phase
                         * of read transaction fails to get ACK.
                         * To avoid time-out error, we issue STOP here,
                         * but do not wait for its completion.
                         * It should be checked after exiting this handler.
                         */
                        uniphier_fi2c_stop(priv);
                        priv->flags |= UNIPHIER_FI2C_DEFER_STOP_COMP;
                        goto complete;
                }
                goto stop;
        }

        if (irq_status & UNIPHIER_FI2C_INT_TE) {
                if (!priv->len)
                        goto data_done;

                uniphier_fi2c_fill_txfifo(priv, false);
                goto handled;
        }

        if (irq_status & (UNIPHIER_FI2C_INT_RF | UNIPHIER_FI2C_INT_RB)) {
                uniphier_fi2c_drain_rxfifo(priv);
                /*
                 * If the number of bytes to read is multiple of the FIFO size
                 * (msg->len == 8, 16, 24, ...), the INT_RF bit is set a little
                 * earlier than INT_RB. We wait for INT_RB to confirm the
                 * completion of the current message.
                 */
                if (!priv->len && (irq_status & UNIPHIER_FI2C_INT_RB))
                        goto data_done;

                if (unlikely(priv->flags & UNIPHIER_FI2C_MANUAL_NACK)) {
                        if (priv->len <= UNIPHIER_FI2C_FIFO_SIZE &&
                            !(priv->flags & UNIPHIER_FI2C_BYTE_WISE)) {
                                dev_dbg(&priv->adap.dev,
                                        "enable read byte count IRQ\n");
                                priv->enabled_irqs |= UNIPHIER_FI2C_INT_RB;
                                uniphier_fi2c_set_irqs(priv);
                                priv->flags |= UNIPHIER_FI2C_BYTE_WISE;
                        }
                        if (priv->len <= 1) {
                                dev_dbg(&priv->adap.dev, "set NACK\n");
                                writel(UNIPHIER_FI2C_CR_MST |
                                       UNIPHIER_FI2C_CR_NACK,
                                       priv->membase + UNIPHIER_FI2C_CR);
                        }
                }

                goto handled;
        }

        spin_unlock(&priv->lock);

        return IRQ_NONE;

data_done:
        if (priv->flags & UNIPHIER_FI2C_STOP) {
stop:
                uniphier_fi2c_stop(priv);
        } else {
complete:
                priv->enabled_irqs = 0;
                uniphier_fi2c_set_irqs(priv);
                complete(&priv->comp);
        }

handled:
        /*
         * This controller makes a pause while any bit of the IRQ status is
         * asserted. Clear the asserted bit to kick the controller just before
         * exiting the handler.
         */
        uniphier_fi2c_clear_irqs(priv, irq_status);

        spin_unlock(&priv->lock);

        return IRQ_HANDLED;
}

static void uniphier_fi2c_tx_init(struct uniphier_fi2c_priv *priv, u16 addr,
                                  bool repeat)
{
        priv->enabled_irqs |= UNIPHIER_FI2C_INT_TE;
        uniphier_fi2c_set_irqs(priv);

        /* do not use TX byte counter */
        writel(0, priv->membase + UNIPHIER_FI2C_TBC);
        /* set slave address */
        writel(UNIPHIER_FI2C_DTTX_CMD | addr << 1,
               priv->membase + UNIPHIER_FI2C_DTTX);
        /*
         * First chunk of data. For a repeated START condition, do not write
         * data to the TX fifo here to avoid the timing issue.
         */
        if (!repeat)
                uniphier_fi2c_fill_txfifo(priv, true);
}

static void uniphier_fi2c_rx_init(struct uniphier_fi2c_priv *priv, u16 addr)
{
        priv->flags |= UNIPHIER_FI2C_RD;

        if (likely(priv->len < 256)) {
                /*
                 * If possible, use RX byte counter.
                 * It can automatically handle NACK for the last byte.
                 */
                writel(priv->len, priv->membase + UNIPHIER_FI2C_RBC);
                priv->enabled_irqs |= UNIPHIER_FI2C_INT_RF |
                                      UNIPHIER_FI2C_INT_RB;
        } else {
                /*
                 * The byte counter can not count over 256.  In this case,
                 * do not use it at all.  Drain data when FIFO gets full,
                 * but treat the last portion as a special case.
                 */
                writel(0, priv->membase + UNIPHIER_FI2C_RBC);
                priv->flags |= UNIPHIER_FI2C_MANUAL_NACK;
                priv->enabled_irqs |= UNIPHIER_FI2C_INT_RF;
        }

        uniphier_fi2c_set_irqs(priv);

        /* set slave address with RD bit */
        writel(UNIPHIER_FI2C_DTTX_CMD | UNIPHIER_FI2C_DTTX_RD | addr << 1,
               priv->membase + UNIPHIER_FI2C_DTTX);
}

static void uniphier_fi2c_reset(struct uniphier_fi2c_priv *priv)
{
        writel(UNIPHIER_FI2C_RST_RST, priv->membase + UNIPHIER_FI2C_RST);
}

static void uniphier_fi2c_prepare_operation(struct uniphier_fi2c_priv *priv)
{
        writel(UNIPHIER_FI2C_BRST_FOEN | UNIPHIER_FI2C_BRST_RSCL,
               priv->membase + UNIPHIER_FI2C_BRST);
}

static void uniphier_fi2c_recover(struct uniphier_fi2c_priv *priv)
{
        uniphier_fi2c_reset(priv);
        i2c_recover_bus(&priv->adap);
}

static int uniphier_fi2c_master_xfer_one(struct i2c_adapter *adap,
                                         struct i2c_msg *msg, bool repeat,
                                         bool stop)
{
        struct uniphier_fi2c_priv *priv = i2c_get_adapdata(adap);
        bool is_read = msg->flags & I2C_M_RD;
        unsigned long time_left, flags;

        dev_dbg(&adap->dev, "%s: addr=0x%02x, len=%d, repeat=%d, stop=%d\n",
                is_read ? "receive" : "transmit", msg->addr, msg->len,
                repeat, stop);

        priv->len = msg->len;
        priv->buf = msg->buf;
        priv->enabled_irqs = UNIPHIER_FI2C_INT_FAULTS;
        priv->error = 0;
        priv->flags = 0;

        if (stop)
                priv->flags |= UNIPHIER_FI2C_STOP;

        reinit_completion(&priv->comp);
        uniphier_fi2c_clear_irqs(priv, U32_MAX);
        writel(UNIPHIER_FI2C_RST_TBRST | UNIPHIER_FI2C_RST_RBRST,
               priv->membase + UNIPHIER_FI2C_RST);      /* reset TX/RX FIFO */

        spin_lock_irqsave(&priv->lock, flags);

        if (is_read)
                uniphier_fi2c_rx_init(priv, msg->addr);
        else
                uniphier_fi2c_tx_init(priv, msg->addr, repeat);

        dev_dbg(&adap->dev, "start condition\n");
        /*
         * For a repeated START condition, writing a slave address to the FIFO
         * kicks the controller. So, the UNIPHIER_FI2C_CR register should be
         * written only for a non-repeated START condition.
         */
        if (!repeat)
                writel(UNIPHIER_FI2C_CR_MST | UNIPHIER_FI2C_CR_STA,
                       priv->membase + UNIPHIER_FI2C_CR);

        spin_unlock_irqrestore(&priv->lock, flags);

        time_left = wait_for_completion_timeout(&priv->comp, adap->timeout);

        spin_lock_irqsave(&priv->lock, flags);
        priv->enabled_irqs = 0;
        uniphier_fi2c_set_irqs(priv);
        spin_unlock_irqrestore(&priv->lock, flags);

        if (!time_left) {
                dev_err(&adap->dev, "transaction timeout.\n");
                uniphier_fi2c_recover(priv);
                return -ETIMEDOUT;
        }
        dev_dbg(&adap->dev, "complete\n");

        if (unlikely(priv->flags & UNIPHIER_FI2C_DEFER_STOP_COMP)) {
                u32 status;
                int ret;

                ret = readl_poll_timeout(priv->membase + UNIPHIER_FI2C_SR,
                                         status,
                                         (status & UNIPHIER_FI2C_SR_STS) &&
                                         !(status & UNIPHIER_FI2C_SR_BB),
                                         1, 20);
                if (ret) {
                        dev_err(&adap->dev,
                                "stop condition was not completed.\n");
                        uniphier_fi2c_recover(priv);
                        return ret;
                }
        }

        return priv->error;
}

static int uniphier_fi2c_check_bus_busy(struct i2c_adapter *adap)
{
        struct uniphier_fi2c_priv *priv = i2c_get_adapdata(adap);

        if (readl(priv->membase + UNIPHIER_FI2C_SR) & UNIPHIER_FI2C_SR_DB) {
                if (priv->busy_cnt++ > 3) {
                        /*
                         * If bus busy continues too long, it is probably
                         * in a wrong state.  Try bus recovery.
                         */
                        uniphier_fi2c_recover(priv);
                        priv->busy_cnt = 0;
                }

                return -EAGAIN;
        }

        priv->busy_cnt = 0;
        return 0;
}

static int uniphier_fi2c_master_xfer(struct i2c_adapter *adap,
                                     struct i2c_msg *msgs, int num)
{
        struct i2c_msg *msg, *emsg = msgs + num;
        bool repeat = false;
        int ret;

        ret = uniphier_fi2c_check_bus_busy(adap);
        if (ret)
                return ret;

        for (msg = msgs; msg < emsg; msg++) {
                /* Emit STOP if it is the last message or I2C_M_STOP is set. */
                bool stop = (msg + 1 == emsg) || (msg->flags & I2C_M_STOP);

                ret = uniphier_fi2c_master_xfer_one(adap, msg, repeat, stop);
                if (ret)
                        return ret;

                repeat = !stop;
        }

        return num;
}

static u32 uniphier_fi2c_functionality(struct i2c_adapter *adap)
{
        return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}

static const struct i2c_algorithm uniphier_fi2c_algo = {
        .master_xfer = uniphier_fi2c_master_xfer,
        .functionality = uniphier_fi2c_functionality,
};

static int uniphier_fi2c_get_scl(struct i2c_adapter *adap)
{
        struct uniphier_fi2c_priv *priv = i2c_get_adapdata(adap);

        return !!(readl(priv->membase + UNIPHIER_FI2C_BM) &
                                                        UNIPHIER_FI2C_BM_SCLS);
}

static void uniphier_fi2c_set_scl(struct i2c_adapter *adap, int val)
{
        struct uniphier_fi2c_priv *priv = i2c_get_adapdata(adap);

        writel(val ? UNIPHIER_FI2C_BRST_RSCL : 0,
               priv->membase + UNIPHIER_FI2C_BRST);
}

static int uniphier_fi2c_get_sda(struct i2c_adapter *adap)
{
        struct uniphier_fi2c_priv *priv = i2c_get_adapdata(adap);

        return !!(readl(priv->membase + UNIPHIER_FI2C_BM) &
                                                        UNIPHIER_FI2C_BM_SDAS);
}

static void uniphier_fi2c_unprepare_recovery(struct i2c_adapter *adap)
{
        uniphier_fi2c_prepare_operation(i2c_get_adapdata(adap));
}

static struct i2c_bus_recovery_info uniphier_fi2c_bus_recovery_info = {
        .recover_bus = i2c_generic_scl_recovery,
        .get_scl = uniphier_fi2c_get_scl,
        .set_scl = uniphier_fi2c_set_scl,
        .get_sda = uniphier_fi2c_get_sda,
        .unprepare_recovery = uniphier_fi2c_unprepare_recovery,
};

static void uniphier_fi2c_hw_init(struct uniphier_fi2c_priv *priv)
{
        unsigned int cyc = priv->clk_cycle;
        u32 tmp;

        tmp = readl(priv->membase + UNIPHIER_FI2C_CR);
        tmp |= UNIPHIER_FI2C_CR_MST;
        writel(tmp, priv->membase + UNIPHIER_FI2C_CR);

        uniphier_fi2c_reset(priv);

        /*
         *  Standard-mode: tLOW + tHIGH = 10 us
         *  Fast-mode:     tLOW + tHIGH = 2.5 us
         */
        writel(cyc, priv->membase + UNIPHIER_FI2C_CYC);
        /*
         *  Standard-mode: tLOW = 4.7 us, tHIGH = 4.0 us, tBUF = 4.7 us
         *  Fast-mode:     tLOW = 1.3 us, tHIGH = 0.6 us, tBUF = 1.3 us
         * "tLow/tHIGH = 5/4" meets both.
         */
        writel(cyc * 5 / 9, priv->membase + UNIPHIER_FI2C_LCTL);
        /*
         *  Standard-mode: tHD;STA = 4.0 us, tSU;STA = 4.7 us, tSU;STO = 4.0 us
         *  Fast-mode:     tHD;STA = 0.6 us, tSU;STA = 0.6 us, tSU;STO = 0.6 us
         */
        writel(cyc / 2, priv->membase + UNIPHIER_FI2C_SSUT);
        /*
         *  Standard-mode: tSU;DAT = 250 ns
         *  Fast-mode:     tSU;DAT = 100 ns
         */
        writel(cyc / 16, priv->membase + UNIPHIER_FI2C_DSUT);

        uniphier_fi2c_prepare_operation(priv);
}

static int uniphier_fi2c_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct uniphier_fi2c_priv *priv;
        struct resource *regs;
        u32 bus_speed;
        unsigned long clk_rate;
        int irq, ret;

        priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        priv->membase = devm_ioremap_resource(dev, regs);
        if (IS_ERR(priv->membase))
                return PTR_ERR(priv->membase);

        irq = platform_get_irq(pdev, 0);
        if (irq < 0) {
                dev_err(dev, "failed to get IRQ number\n");
                return irq;
        }

        if (of_property_read_u32(dev->of_node, "clock-frequency", &bus_speed))
                bus_speed = UNIPHIER_FI2C_DEFAULT_SPEED;

        if (!bus_speed || bus_speed > UNIPHIER_FI2C_MAX_SPEED) {
                dev_err(dev, "invalid clock-frequency %d\n", bus_speed);
                return -EINVAL;
        }

        priv->clk = devm_clk_get(dev, NULL);
        if (IS_ERR(priv->clk)) {
                dev_err(dev, "failed to get clock\n");
                return PTR_ERR(priv->clk);
        }

        ret = clk_prepare_enable(priv->clk);
        if (ret)
                return ret;

        clk_rate = clk_get_rate(priv->clk);
        if (!clk_rate) {
                dev_err(dev, "input clock rate should not be zero\n");
                ret = -EINVAL;
                goto disable_clk;
        }

        priv->clk_cycle = clk_rate / bus_speed;
        init_completion(&priv->comp);
        spin_lock_init(&priv->lock);
        priv->adap.owner = THIS_MODULE;
        priv->adap.algo = &uniphier_fi2c_algo;
        priv->adap.dev.parent = dev;
        priv->adap.dev.of_node = dev->of_node;
        strlcpy(priv->adap.name, "UniPhier FI2C", sizeof(priv->adap.name));
        priv->adap.bus_recovery_info = &uniphier_fi2c_bus_recovery_info;
        i2c_set_adapdata(&priv->adap, priv);
        platform_set_drvdata(pdev, priv);

        uniphier_fi2c_hw_init(priv);

        ret = devm_request_irq(dev, irq, uniphier_fi2c_interrupt, 0,
                               pdev->name, priv);
        if (ret) {
                dev_err(dev, "failed to request irq %d\n", irq);
                goto disable_clk;
        }

        ret = i2c_add_adapter(&priv->adap);
disable_clk:
        if (ret)
                clk_disable_unprepare(priv->clk);

        return ret;
}

static int uniphier_fi2c_remove(struct platform_device *pdev)
{
        struct uniphier_fi2c_priv *priv = platform_get_drvdata(pdev);

        i2c_del_adapter(&priv->adap);
        clk_disable_unprepare(priv->clk);

        return 0;
}

static int __maybe_unused uniphier_fi2c_suspend(struct device *dev)
{
        struct uniphier_fi2c_priv *priv = dev_get_drvdata(dev);

        clk_disable_unprepare(priv->clk);

        return 0;
}

static int __maybe_unused uniphier_fi2c_resume(struct device *dev)
{
        struct uniphier_fi2c_priv *priv = dev_get_drvdata(dev);
        int ret;

        ret = clk_prepare_enable(priv->clk);
        if (ret)
                return ret;

        uniphier_fi2c_hw_init(priv);

        return 0;
}

static const struct dev_pm_ops uniphier_fi2c_pm_ops = {
        SET_SYSTEM_SLEEP_PM_OPS(uniphier_fi2c_suspend, uniphier_fi2c_resume)
};

static const struct of_device_id uniphier_fi2c_match[] = {
        { .compatible = "socionext,uniphier-fi2c" },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, uniphier_fi2c_match);

static struct platform_driver uniphier_fi2c_drv = {
        .probe  = uniphier_fi2c_probe,
        .remove = uniphier_fi2c_remove,
        .driver = {
                .name  = "uniphier-fi2c",
                .of_match_table = uniphier_fi2c_match,
                .pm = &uniphier_fi2c_pm_ops,
        },
};
module_platform_driver(uniphier_fi2c_drv);

MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@socionext.com>");
MODULE_DESCRIPTION("UniPhier FIFO-builtin I2C bus driver");
MODULE_LICENSE("GPL");