// SPDX-License-Identifier: GPL-2.0+
/*
 * (C) Copyright 2009
 * Vipin Kumar, ST Micoelectronics, vipin.kumar@st.com.
 */

#include <common.h>
#include <clk.h>
#include <dm.h>
#include <i2c.h>
#include <log.h>
#include <malloc.h>
#include <pci.h>
#include <reset.h>
#include <asm/io.h>
#include <linux/delay.h>
#include "designware_i2c.h"
#include <dm/device_compat.h>
#include <linux/err.h>

/*
 * This assigned unique hex value is constant and is derived from the two ASCII
 * letters 'DW' followed by a 16-bit unsigned number
 */
#define DW_I2C_COMP_TYPE        0x44570140

static int dw_i2c_enable(struct i2c_regs *i2c_base, bool enable)
{
        u32 ena = enable ? IC_ENABLE_0B : 0;
        int timeout = 100;

        do {
                writel(ena, &i2c_base->ic_enable);
                if ((readl(&i2c_base->ic_enable_status) & IC_ENABLE_0B) == ena)
                        return 0;

                /*
                 * Wait 10 times the signaling period of the highest I2C
                 * transfer supported by the driver (for 400KHz this is
                 * 25us) as described in the DesignWare I2C databook.
                 */
                udelay(25);
        } while (timeout--);
        printf("timeout in %sabling I2C adapter\n", enable ? "en" : "dis");

        return -ETIMEDOUT;
}

/* High and low times in different speed modes (in ns) */
enum {
        /* SDA Hold Time */
        DEFAULT_SDA_HOLD_TIME           = 300,
};

/**
 * calc_counts() - Convert a period to a number of IC clk cycles
 *
 * @ic_clk: Input clock in Hz
 * @period_ns: Period to represent, in ns
 * @return calculated count
 */
static uint calc_counts(uint ic_clk, uint period_ns)
{
        return DIV_ROUND_UP(ic_clk / 1000 * period_ns, NANO_TO_KILO);
}

/**
 * struct i2c_mode_info - Information about an I2C speed mode
 *
 * Each speed mode has its own characteristics. This struct holds these to aid
 * calculations in dw_i2c_calc_timing().
 *
 * @speed: Speed in Hz
 * @min_scl_lowtime_ns: Minimum value for SCL low period in ns
 * @min_scl_hightime_ns: Minimum value for SCL high period in ns
 * @def_rise_time_ns: Default rise time in ns
 * @def_fall_time_ns: Default fall time in ns
 */
struct i2c_mode_info {
        int speed;
        int min_scl_hightime_ns;
        int min_scl_lowtime_ns;
        int def_rise_time_ns;
        int def_fall_time_ns;
};

static const struct i2c_mode_info info_for_mode[] = {
        [IC_SPEED_MODE_STANDARD] = {
                I2C_SPEED_STANDARD_RATE,
                MIN_SS_SCL_HIGHTIME,
                MIN_SS_SCL_LOWTIME,
                1000,
                300,
        },
        [IC_SPEED_MODE_FAST] = {
                I2C_SPEED_FAST_RATE,
                MIN_FS_SCL_HIGHTIME,
                MIN_FS_SCL_LOWTIME,
                300,
                300,
        },
        [IC_SPEED_MODE_FAST_PLUS] = {
                I2C_SPEED_FAST_PLUS_RATE,
                MIN_FP_SCL_HIGHTIME,
                MIN_FP_SCL_LOWTIME,
                260,
                500,
        },
        [IC_SPEED_MODE_HIGH] = {
                I2C_SPEED_HIGH_RATE,
                MIN_HS_SCL_HIGHTIME,
                MIN_HS_SCL_LOWTIME,
                120,
                120,
        },
};

/**
 * dw_i2c_calc_timing() - Calculate the timings to use for a bus
 *
 * @priv: Bus private information (NULL if not using driver model)
 * @mode: Speed mode to use
 * @ic_clk: IC clock speed in Hz
 * @spk_cnt: Spike-suppression count
 * @config: Returns value to use
 * @return 0 if OK, -EINVAL if the calculation failed due to invalid data
 */
static int dw_i2c_calc_timing(struct dw_i2c *priv, enum i2c_speed_mode mode,
                              int ic_clk, int spk_cnt,
                              struct dw_i2c_speed_config *config)
{
        int fall_cnt, rise_cnt, min_tlow_cnt, min_thigh_cnt;
        int hcnt, lcnt, period_cnt, diff, tot;
        int sda_hold_time_ns, scl_rise_time_ns, scl_fall_time_ns;
        const struct i2c_mode_info *info;

        /*
         * Find the period, rise, fall, min tlow, and min thigh in terms of
         * counts of the IC clock
         */
        info = &info_for_mode[mode];
        period_cnt = ic_clk / info->speed;
        scl_rise_time_ns = priv && priv->scl_rise_time_ns ?
                 priv->scl_rise_time_ns : info->def_rise_time_ns;
        scl_fall_time_ns = priv && priv->scl_fall_time_ns ?
                 priv->scl_fall_time_ns : info->def_fall_time_ns;
        rise_cnt = calc_counts(ic_clk, scl_rise_time_ns);
        fall_cnt = calc_counts(ic_clk, scl_fall_time_ns);
        min_tlow_cnt = calc_counts(ic_clk, info->min_scl_lowtime_ns);
        min_thigh_cnt = calc_counts(ic_clk, info->min_scl_hightime_ns);

        debug("dw_i2c: mode %d, ic_clk %d, speed %d, period %d rise %d fall %d tlow %d thigh %d spk %d\n",
              mode, ic_clk, info->speed, period_cnt, rise_cnt, fall_cnt,
              min_tlow_cnt, min_thigh_cnt, spk_cnt);

        /*
         * Back-solve for hcnt and lcnt according to the following equations:
         * SCL_High_time = [(HCNT + IC_*_SPKLEN + 7) * ic_clk] + SCL_Fall_time
         * SCL_Low_time = [(LCNT + 1) * ic_clk] - SCL_Fall_time + SCL_Rise_time
         */
        hcnt = min_thigh_cnt - fall_cnt - 7 - spk_cnt;
        lcnt = min_tlow_cnt - rise_cnt + fall_cnt - 1;

        if (hcnt < 0 || lcnt < 0) {
                debug("dw_i2c: bad counts. hcnt = %d lcnt = %d\n", hcnt, lcnt);
                return log_msg_ret("counts", -EINVAL);
        }

        /*
         * Now add things back up to ensure the period is hit. If it is off,
         * split the difference and bias to lcnt for remainder
         */
        tot = hcnt + lcnt + 7 + spk_cnt + rise_cnt + 1;

        if (tot < period_cnt) {
                diff = (period_cnt - tot) / 2;
                hcnt += diff;
                lcnt += diff;
                tot = hcnt + lcnt + 7 + spk_cnt + rise_cnt + 1;
                lcnt += period_cnt - tot;
        }

        config->scl_lcnt = lcnt;
        config->scl_hcnt = hcnt;

        /* Use internal default unless other value is specified */
        sda_hold_time_ns = priv && priv->sda_hold_time_ns ?
                 priv->sda_hold_time_ns : DEFAULT_SDA_HOLD_TIME;
        config->sda_hold = calc_counts(ic_clk, sda_hold_time_ns);

        debug("dw_i2c: hcnt = %d lcnt = %d sda hold = %d\n", hcnt, lcnt,
              config->sda_hold);

        return 0;
}

/**
 * calc_bus_speed() - Calculate the config to use for a particular i2c speed
 *
 * @priv: Private information for the driver (NULL if not using driver model)
 * @i2c_base: Registers for the I2C controller
 * @speed: Required i2c speed in Hz
 * @bus_clk: Input clock to the I2C controller in Hz (e.g. IC_CLK)
 * @config: Returns the config to use for this speed
 * @return 0 if OK, -ve on error
 */
static int calc_bus_speed(struct dw_i2c *priv, struct i2c_regs *regs, int speed,
                          ulong bus_clk, struct dw_i2c_speed_config *config)
{
        const struct dw_scl_sda_cfg *scl_sda_cfg = NULL;
        enum i2c_speed_mode i2c_spd;
        int spk_cnt;
        int ret;

        if (priv)
                scl_sda_cfg = priv->scl_sda_cfg;
        /* Allow high speed if there is no config, or the config allows it */
        if (speed >= I2C_SPEED_HIGH_RATE)
                i2c_spd = IC_SPEED_MODE_HIGH;
        else if (speed >= I2C_SPEED_FAST_PLUS_RATE)
                i2c_spd = IC_SPEED_MODE_FAST_PLUS;
        else if (speed >= I2C_SPEED_FAST_RATE)
                i2c_spd = IC_SPEED_MODE_FAST;
        else
                i2c_spd = IC_SPEED_MODE_STANDARD;

        /* Check is high speed possible and fall back to fast mode if not */
        if (i2c_spd == IC_SPEED_MODE_HIGH) {
                u32 comp_param1;

                comp_param1 = readl(&regs->comp_param1);
                if ((comp_param1 & DW_IC_COMP_PARAM_1_SPEED_MODE_MASK)
                                != DW_IC_COMP_PARAM_1_SPEED_MODE_HIGH)
                        i2c_spd = IC_SPEED_MODE_FAST;
        }

        /* Get the proper spike-suppression count based on target speed */
        if (!priv || !priv->has_spk_cnt)
                spk_cnt = 0;
        else if (i2c_spd >= IC_SPEED_MODE_HIGH)
                spk_cnt = readl(&regs->hs_spklen);
        else
                spk_cnt = readl(&regs->fs_spklen);
        if (scl_sda_cfg) {
                config->sda_hold = scl_sda_cfg->sda_hold;
                if (i2c_spd == IC_SPEED_MODE_STANDARD) {
                        config->scl_hcnt = scl_sda_cfg->ss_hcnt;
                        config->scl_lcnt = scl_sda_cfg->ss_lcnt;
                } else if (i2c_spd == IC_SPEED_MODE_HIGH) {
                        config->scl_hcnt = scl_sda_cfg->hs_hcnt;
                        config->scl_lcnt = scl_sda_cfg->hs_lcnt;
                } else {
                        config->scl_hcnt = scl_sda_cfg->fs_hcnt;
                        config->scl_lcnt = scl_sda_cfg->fs_lcnt;
                }
        } else {
                ret = dw_i2c_calc_timing(priv, i2c_spd, bus_clk, spk_cnt,
                                         config);
                if (ret)
                        return log_msg_ret("gen_confg", ret);
        }
        config->speed_mode = i2c_spd;

        return 0;
}

/**
 * _dw_i2c_set_bus_speed() - Set the i2c speed
 *
 * @priv: Private information for the driver (NULL if not using driver model)
 * @i2c_base: Registers for the I2C controller
 * @speed: Required i2c speed in Hz
 * @bus_clk: Input clock to the I2C controller in Hz (e.g. IC_CLK)
 * @return 0 if OK, -ve on error
 */
static int _dw_i2c_set_bus_speed(struct dw_i2c *priv, struct i2c_regs *i2c_base,
                                 unsigned int speed, unsigned int bus_clk)
{
        struct dw_i2c_speed_config config;
        unsigned int cntl;
        unsigned int ena;
        int ret;

        ret = calc_bus_speed(priv, i2c_base, speed, bus_clk, &config);
        if (ret)
                return ret;

        /* Get enable setting for restore later */
        ena = readl(&i2c_base->ic_enable) & IC_ENABLE_0B;

        /* to set speed cltr must be disabled */
        dw_i2c_enable(i2c_base, false);

        cntl = (readl(&i2c_base->ic_con) & (~IC_CON_SPD_MSK));

        switch (config.speed_mode) {
        case IC_SPEED_MODE_HIGH:
                cntl |= IC_CON_SPD_HS;
                writel(config.scl_hcnt, &i2c_base->ic_hs_scl_hcnt);
                writel(config.scl_lcnt, &i2c_base->ic_hs_scl_lcnt);
                break;
        case IC_SPEED_MODE_STANDARD:
                cntl |= IC_CON_SPD_SS;
                writel(config.scl_hcnt, &i2c_base->ic_ss_scl_hcnt);
                writel(config.scl_lcnt, &i2c_base->ic_ss_scl_lcnt);
                break;
        case IC_SPEED_MODE_FAST_PLUS:
        case IC_SPEED_MODE_FAST:
        default:
                cntl |= IC_CON_SPD_FS;
                writel(config.scl_hcnt, &i2c_base->ic_fs_scl_hcnt);
                writel(config.scl_lcnt, &i2c_base->ic_fs_scl_lcnt);
                break;
        }

        writel(cntl, &i2c_base->ic_con);

        /* Configure SDA Hold Time if required */
        if (config.sda_hold)
                writel(config.sda_hold, &i2c_base->ic_sda_hold);

        /* Restore back i2c now speed set */
        if (ena == IC_ENABLE_0B)
                dw_i2c_enable(i2c_base, true);
        if (priv)
                priv->config = config;

        return 0;
}

int dw_i2c_gen_speed_config(const struct udevice *dev, int speed_hz,
                            struct dw_i2c_speed_config *config)
{
        struct dw_i2c *priv = dev_get_priv(dev);
        ulong rate;
        int ret;

#if CONFIG_IS_ENABLED(CLK)
        rate = clk_get_rate(&priv->clk);
        if (IS_ERR_VALUE(rate))
                return log_msg_ret("clk", -EINVAL);
#else
        rate = IC_CLK;
#endif

        ret = calc_bus_speed(priv, priv->regs, speed_hz, rate, config);
        if (ret)
                printf("%s: ret=%d\n", __func__, ret);
        if (ret)
                return log_msg_ret("calc_bus_speed", ret);

        return 0;
}

/*
 * i2c_setaddress - Sets the target slave address
 * @i2c_addr:   target i2c address
 *
 * Sets the target slave address.
 */
static void i2c_setaddress(struct i2c_regs *i2c_base, unsigned int i2c_addr)
{
        /* Disable i2c */
        dw_i2c_enable(i2c_base, false);

        writel(i2c_addr, &i2c_base->ic_tar);

        /* Enable i2c */
        dw_i2c_enable(i2c_base, true);
}

/*
 * i2c_flush_rxfifo - Flushes the i2c RX FIFO
 *
 * Flushes the i2c RX FIFO
 */
static void i2c_flush_rxfifo(struct i2c_regs *i2c_base)
{
        while (readl(&i2c_base->ic_status) & IC_STATUS_RFNE)
                readl(&i2c_base->ic_cmd_data);
}

/*
 * i2c_wait_for_bb - Waits for bus busy
 *
 * Waits for bus busy
 */
static int i2c_wait_for_bb(struct i2c_regs *i2c_base)
{
        unsigned long start_time_bb = get_timer(0);

        while ((readl(&i2c_base->ic_status) & IC_STATUS_MA) ||
               !(readl(&i2c_base->ic_status) & IC_STATUS_TFE)) {

                /* Evaluate timeout */
                if (get_timer(start_time_bb) > (unsigned long)(I2C_BYTE_TO_BB))
                        return 1;
        }

        return 0;
}

static int i2c_xfer_init(struct i2c_regs *i2c_base, uchar chip, uint addr,
                         int alen)
{
        if (i2c_wait_for_bb(i2c_base))
                return 1;

        i2c_setaddress(i2c_base, chip);
        while (alen) {
                alen--;
                /* high byte address going out first */
                writel((addr >> (alen * 8)) & 0xff,
                       &i2c_base->ic_cmd_data);
        }
        return 0;
}

static int i2c_xfer_finish(struct i2c_regs *i2c_base)
{
        ulong start_stop_det = get_timer(0);

        while (1) {
                if ((readl(&i2c_base->ic_raw_intr_stat) & IC_STOP_DET)) {
                        readl(&i2c_base->ic_clr_stop_det);
                        break;
                } else if (get_timer(start_stop_det) > I2C_STOPDET_TO) {
                        break;
                }
        }

        if (i2c_wait_for_bb(i2c_base)) {
                printf("Timed out waiting for bus\n");
                return 1;
        }

        i2c_flush_rxfifo(i2c_base);

        return 0;
}

/*
 * i2c_read - Read from i2c memory
 * @chip:       target i2c address
 * @addr:       address to read from
 * @alen:
 * @buffer:     buffer for read data
 * @len:        no of bytes to be read
 *
 * Read from i2c memory.
 */
static int __dw_i2c_read(struct i2c_regs *i2c_base, u8 dev, uint addr,
                         int alen, u8 *buffer, int len)
{
        unsigned long start_time_rx;
        unsigned int active = 0;

#ifdef CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW
        /*
         * EEPROM chips that implement "address overflow" are ones
         * like Catalyst 24WC04/08/16 which has 9/10/11 bits of
         * address and the extra bits end up in the "chip address"
         * bit slots. This makes a 24WC08 (1Kbyte) chip look like
         * four 256 byte chips.
         *
         * Note that we consider the length of the address field to
         * still be one byte because the extra address bits are
         * hidden in the chip address.
         */
        dev |= ((addr >> (alen * 8)) & CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW);
        addr &= ~(CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW << (alen * 8));

        debug("%s: fix addr_overflow: dev %02x addr %02x\n", __func__, dev,
              addr);
#endif

        if (i2c_xfer_init(i2c_base, dev, addr, alen))
                return 1;

        start_time_rx = get_timer(0);
        while (len) {
                if (!active) {
                        /*
                         * Avoid writing to ic_cmd_data multiple times
                         * in case this loop spins too quickly and the
                         * ic_status RFNE bit isn't set after the first
                         * write. Subsequent writes to ic_cmd_data can
                         * trigger spurious i2c transfer.
                         */
                        if (len == 1)
                                writel(IC_CMD | IC_STOP, &i2c_base->ic_cmd_data);
                        else
                                writel(IC_CMD, &i2c_base->ic_cmd_data);
                        active = 1;
                }

                if (readl(&i2c_base->ic_status) & IC_STATUS_RFNE) {
                        *buffer++ = (uchar)readl(&i2c_base->ic_cmd_data);
                        len--;
                        start_time_rx = get_timer(0);
                        active = 0;
                } else if (get_timer(start_time_rx) > I2C_BYTE_TO) {
                        return 1;
                }
        }

        return i2c_xfer_finish(i2c_base);
}

/*
 * i2c_write - Write to i2c memory
 * @chip:       target i2c address
 * @addr:       address to read from
 * @alen:
 * @buffer:     buffer for read data
 * @len:        no of bytes to be read
 *
 * Write to i2c memory.
 */
static int __dw_i2c_write(struct i2c_regs *i2c_base, u8 dev, uint addr,
                          int alen, u8 *buffer, int len)
{
        int nb = len;
        unsigned long start_time_tx;

#ifdef CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW
        /*
         * EEPROM chips that implement "address overflow" are ones
         * like Catalyst 24WC04/08/16 which has 9/10/11 bits of
         * address and the extra bits end up in the "chip address"
         * bit slots. This makes a 24WC08 (1Kbyte) chip look like
         * four 256 byte chips.
         *
         * Note that we consider the length of the address field to
         * still be one byte because the extra address bits are
         * hidden in the chip address.
         */
        dev |= ((addr >> (alen * 8)) & CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW);
        addr &= ~(CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW << (alen * 8));

        debug("%s: fix addr_overflow: dev %02x addr %02x\n", __func__, dev,
              addr);
#endif

        if (i2c_xfer_init(i2c_base, dev, addr, alen))
                return 1;

        start_time_tx = get_timer(0);
        while (len) {
                if (readl(&i2c_base->ic_status) & IC_STATUS_TFNF) {
                        if (--len == 0) {
                                writel(*buffer | IC_STOP,
                                       &i2c_base->ic_cmd_data);
                        } else {
                                writel(*buffer, &i2c_base->ic_cmd_data);
                        }
                        buffer++;
                        start_time_tx = get_timer(0);

                } else if (get_timer(start_time_tx) > (nb * I2C_BYTE_TO)) {
                                printf("Timed out. i2c write Failed\n");
                                return 1;
                }
        }

        return i2c_xfer_finish(i2c_base);
}

/*
 * __dw_i2c_init - Init function
 * @speed:      required i2c speed
 * @slaveaddr:  slave address for the device
 *
 * Initialization function.
 */
static int __dw_i2c_init(struct i2c_regs *i2c_base, int speed, int slaveaddr)
{
        int ret;

        /* Disable i2c */
        ret = dw_i2c_enable(i2c_base, false);
        if (ret)
                return ret;

        writel(IC_CON_SD | IC_CON_RE | IC_CON_SPD_FS | IC_CON_MM,
               &i2c_base->ic_con);
        writel(IC_RX_TL, &i2c_base->ic_rx_tl);
        writel(IC_TX_TL, &i2c_base->ic_tx_tl);
        writel(IC_STOP_DET, &i2c_base->ic_intr_mask);
#if !CONFIG_IS_ENABLED(DM_I2C)
        _dw_i2c_set_bus_speed(NULL, i2c_base, speed, IC_CLK);
        writel(slaveaddr, &i2c_base->ic_sar);
#endif

        /* Enable i2c */
        ret = dw_i2c_enable(i2c_base, true);
        if (ret)
                return ret;

        return 0;
}

#if !CONFIG_IS_ENABLED(DM_I2C)
/*
 * The legacy I2C functions. These need to get removed once
 * all users of this driver are converted to DM.
 */
static struct i2c_regs *i2c_get_base(struct i2c_adapter *adap)
{
        switch (adap->hwadapnr) {
#if CONFIG_SYS_I2C_BUS_MAX >= 4
        case 3:
                return (struct i2c_regs *)CONFIG_SYS_I2C_BASE3;
#endif
#if CONFIG_SYS_I2C_BUS_MAX >= 3
        case 2:
                return (struct i2c_regs *)CONFIG_SYS_I2C_BASE2;
#endif
#if CONFIG_SYS_I2C_BUS_MAX >= 2
        case 1:
                return (struct i2c_regs *)CONFIG_SYS_I2C_BASE1;
#endif
        case 0:
                return (struct i2c_regs *)CONFIG_SYS_I2C_BASE;
        default:
                printf("Wrong I2C-adapter number %d\n", adap->hwadapnr);
        }

        return NULL;
}

static unsigned int dw_i2c_set_bus_speed(struct i2c_adapter *adap,
                                         unsigned int speed)
{
        adap->speed = speed;
        return _dw_i2c_set_bus_speed(NULL, i2c_get_base(adap), speed, IC_CLK);
}

static void dw_i2c_init(struct i2c_adapter *adap, int speed, int slaveaddr)
{
        __dw_i2c_init(i2c_get_base(adap), speed, slaveaddr);
}

static int dw_i2c_read(struct i2c_adapter *adap, u8 dev, uint addr,
                       int alen, u8 *buffer, int len)
{
        return __dw_i2c_read(i2c_get_base(adap), dev, addr, alen, buffer, len);
}

static int dw_i2c_write(struct i2c_adapter *adap, u8 dev, uint addr,
                        int alen, u8 *buffer, int len)
{
        return __dw_i2c_write(i2c_get_base(adap), dev, addr, alen, buffer, len);
}

/* dw_i2c_probe - Probe the i2c chip */
static int dw_i2c_probe(struct i2c_adapter *adap, u8 dev)
{
        struct i2c_regs *i2c_base = i2c_get_base(adap);
        u32 tmp;
        int ret;

        /*
         * Try to read the first location of the chip.
         */
        ret = __dw_i2c_read(i2c_base, dev, 0, 1, (uchar *)&tmp, 1);
        if (ret)
                dw_i2c_init(adap, adap->speed, adap->slaveaddr);

        return ret;
}

U_BOOT_I2C_ADAP_COMPLETE(dw_0, dw_i2c_init, dw_i2c_probe, dw_i2c_read,
                         dw_i2c_write, dw_i2c_set_bus_speed,
                         CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE, 0)

#else /* CONFIG_DM_I2C */
/* The DM I2C functions */

static int designware_i2c_xfer(struct udevice *bus, struct i2c_msg *msg,
                               int nmsgs)
{
        struct dw_i2c *i2c = dev_get_priv(bus);
        int ret;

        debug("i2c_xfer: %d messages\n", nmsgs);
        for (; nmsgs > 0; nmsgs--, msg++) {
                debug("i2c_xfer: chip=0x%x, len=0x%x\n", msg->addr, msg->len);
                if (msg->flags & I2C_M_RD) {
                        ret = __dw_i2c_read(i2c->regs, msg->addr, 0, 0,
                                            msg->buf, msg->len);
                } else {
                        ret = __dw_i2c_write(i2c->regs, msg->addr, 0, 0,
                                             msg->buf, msg->len);
                }
                if (ret) {
                        debug("i2c_write: error sending\n");
                        return -EREMOTEIO;
                }
        }

        return 0;
}

static int designware_i2c_set_bus_speed(struct udevice *bus, unsigned int speed)
{
        struct dw_i2c *i2c = dev_get_priv(bus);
        ulong rate;

#if CONFIG_IS_ENABLED(CLK)
        rate = clk_get_rate(&i2c->clk);
        if (IS_ERR_VALUE(rate))
                return log_ret(-EINVAL);
#else
        rate = IC_CLK;
#endif
        return _dw_i2c_set_bus_speed(i2c, i2c->regs, speed, rate);
}

static int designware_i2c_probe_chip(struct udevice *bus, uint chip_addr,
                                     uint chip_flags)
{
        struct dw_i2c *i2c = dev_get_priv(bus);
        struct i2c_regs *i2c_base = i2c->regs;
        u32 tmp;
        int ret;

        /* Try to read the first location of the chip */
        ret = __dw_i2c_read(i2c_base, chip_addr, 0, 1, (uchar *)&tmp, 1);
        if (ret)
                __dw_i2c_init(i2c_base, 0, 0);

        return ret;
}

int designware_i2c_of_to_plat(struct udevice *bus)
{
        struct dw_i2c *priv = dev_get_priv(bus);
        int ret;

        if (!priv->regs)
                priv->regs = dev_read_addr_ptr(bus);
        dev_read_u32(bus, "i2c-scl-rising-time-ns", &priv->scl_rise_time_ns);
        dev_read_u32(bus, "i2c-scl-falling-time-ns", &priv->scl_fall_time_ns);
        dev_read_u32(bus, "i2c-sda-hold-time-ns", &priv->sda_hold_time_ns);

        ret = reset_get_bulk(bus, &priv->resets);
        if (ret) {
                if (ret != -ENOTSUPP)
                        dev_warn(bus, "Can't get reset: %d\n", ret);
        } else {
                reset_deassert_bulk(&priv->resets);
        }

#if CONFIG_IS_ENABLED(CLK)
        ret = clk_get_by_index(bus, 0, &priv->clk);
        if (ret)
                return ret;

        ret = clk_enable(&priv->clk);
        if (ret && ret != -ENOSYS && ret != -ENOTSUPP) {
                clk_free(&priv->clk);
                dev_err(bus, "failed to enable clock\n");
                return ret;
        }
#endif

        return 0;
}

int designware_i2c_probe(struct udevice *bus)
{
        struct dw_i2c *priv = dev_get_priv(bus);
        uint comp_type;

        comp_type = readl(&priv->regs->comp_type);
        if (comp_type != DW_I2C_COMP_TYPE) {
                log_err("I2C bus %s has unknown type %#x\n", bus->name,
                        comp_type);
                return -ENXIO;
        }

        log_debug("I2C bus %s version %#x\n", bus->name,
                  readl(&priv->regs->comp_version));

        return __dw_i2c_init(priv->regs, 0, 0);
}

int designware_i2c_remove(struct udevice *dev)
{
        struct dw_i2c *priv = dev_get_priv(dev);

#if CONFIG_IS_ENABLED(CLK)
        clk_disable(&priv->clk);
        clk_free(&priv->clk);
#endif

        return reset_release_bulk(&priv->resets);
}

const struct dm_i2c_ops designware_i2c_ops = {
        .xfer           = designware_i2c_xfer,
        .probe_chip     = designware_i2c_probe_chip,
        .set_bus_speed  = designware_i2c_set_bus_speed,
};

static const struct udevice_id designware_i2c_ids[] = {
        { .compatible = "snps,designware-i2c" },
        { }
};

U_BOOT_DRIVER(i2c_designware) = {
        .name   = "i2c_designware",
        .id     = UCLASS_I2C,
        .of_match = designware_i2c_ids,
        .of_to_plat = designware_i2c_of_to_plat,
        .probe  = designware_i2c_probe,
        .priv_auto      = sizeof(struct dw_i2c),
        .remove = designware_i2c_remove,
        .flags  = DM_FLAG_OS_PREPARE,
        .ops    = &designware_i2c_ops,
};

#endif /* CONFIG_DM_I2C */