// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (c) 2016, Google Inc
 *
 * (C) Copyright 2002
 * David Mueller, ELSOFT AG, d.mueller@elsoft.ch
 */

#include <common.h>
#include <dm.h>
#include <i2c.h>
#include <log.h>
#include <asm/arch/clk.h>
#include <asm/arch/cpu.h>
#include <asm/arch/pinmux.h>
#include <asm/global_data.h>
#include <linux/delay.h>
#include "s3c24x0_i2c.h"

DECLARE_GLOBAL_DATA_PTR;

/* HSI2C-specific register description */

/* I2C_CTL Register bits */
#define HSI2C_FUNC_MODE_I2C             (1u << 0)
#define HSI2C_MASTER                    (1u << 3)
#define HSI2C_RXCHON                    (1u << 6)       /* Write/Send */
#define HSI2C_TXCHON                    (1u << 7)       /* Read/Receive */
#define HSI2C_SW_RST                    (1u << 31)

/* I2C_FIFO_CTL Register bits */
#define HSI2C_RXFIFO_EN                 (1u << 0)
#define HSI2C_TXFIFO_EN                 (1u << 1)
#define HSI2C_TXFIFO_TRIGGER_LEVEL      (0x20 << 16)
#define HSI2C_RXFIFO_TRIGGER_LEVEL      (0x20 << 4)

/* I2C_TRAILING_CTL Register bits */
#define HSI2C_TRAILING_COUNT            (0xff)

/* I2C_INT_EN Register bits */
#define HSI2C_TX_UNDERRUN_EN            (1u << 2)
#define HSI2C_TX_OVERRUN_EN             (1u << 3)
#define HSI2C_RX_UNDERRUN_EN            (1u << 4)
#define HSI2C_RX_OVERRUN_EN             (1u << 5)
#define HSI2C_INT_TRAILING_EN           (1u << 6)
#define HSI2C_INT_I2C_EN                (1u << 9)

#define HSI2C_INT_ERROR_MASK    (HSI2C_TX_UNDERRUN_EN |\
                                 HSI2C_TX_OVERRUN_EN  |\
                                 HSI2C_RX_UNDERRUN_EN |\
                                 HSI2C_RX_OVERRUN_EN  |\
                                 HSI2C_INT_TRAILING_EN)

/* I2C_CONF Register bits */
#define HSI2C_AUTO_MODE                 (1u << 31)
#define HSI2C_10BIT_ADDR_MODE           (1u << 30)
#define HSI2C_HS_MODE                   (1u << 29)

/* I2C_AUTO_CONF Register bits */
#define HSI2C_READ_WRITE                (1u << 16)
#define HSI2C_STOP_AFTER_TRANS          (1u << 17)
#define HSI2C_MASTER_RUN                (1u << 31)

/* I2C_TIMEOUT Register bits */
#define HSI2C_TIMEOUT_EN                (1u << 31)

/* I2C_TRANS_STATUS register bits */
#define HSI2C_MASTER_BUSY               (1u << 17)
#define HSI2C_SLAVE_BUSY                (1u << 16)
#define HSI2C_TIMEOUT_AUTO              (1u << 4)
#define HSI2C_NO_DEV                    (1u << 3)
#define HSI2C_NO_DEV_ACK                (1u << 2)
#define HSI2C_TRANS_ABORT               (1u << 1)
#define HSI2C_TRANS_SUCCESS             (1u << 0)
#define HSI2C_TRANS_ERROR_MASK  (HSI2C_TIMEOUT_AUTO |\
                                 HSI2C_NO_DEV | HSI2C_NO_DEV_ACK |\
                                 HSI2C_TRANS_ABORT)
#define HSI2C_TRANS_FINISHED_MASK (HSI2C_TRANS_ERROR_MASK | HSI2C_TRANS_SUCCESS)


/* I2C_FIFO_STAT Register bits */
#define HSI2C_RX_FIFO_EMPTY             (1u << 24)
#define HSI2C_RX_FIFO_FULL              (1u << 23)
#define HSI2C_TX_FIFO_EMPTY             (1u << 8)
#define HSI2C_TX_FIFO_FULL              (1u << 7)
#define HSI2C_RX_FIFO_LEVEL(x)          (((x) >> 16) & 0x7f)
#define HSI2C_TX_FIFO_LEVEL(x)          ((x) & 0x7f)

#define HSI2C_SLV_ADDR_MAS(x)           ((x & 0x3ff) << 10)

#define HSI2C_TIMEOUT_US 10000 /* 10 ms, finer granularity */

/*
 * Wait for transfer completion.
 *
 * This function reads the interrupt status register waiting for the INT_I2C
 * bit to be set, which indicates copletion of a transaction.
 *
 * @param i2c: pointer to the appropriate register bank
 *
 * @return: I2C_OK in case of successful completion, I2C_NOK_TIMEOUT in case
 *          the status bits do not get set in time, or an approrpiate error
 *          value in case of transfer errors.
 */
static int hsi2c_wait_for_trx(struct exynos5_hsi2c *i2c)
{
        int i = HSI2C_TIMEOUT_US;

        while (i-- > 0) {
                u32 int_status = readl(&i2c->usi_int_stat);

                if (int_status & HSI2C_INT_I2C_EN) {
                        u32 trans_status = readl(&i2c->usi_trans_status);

                        /* Deassert pending interrupt. */
                        writel(int_status, &i2c->usi_int_stat);

                        if (trans_status & HSI2C_NO_DEV_ACK) {
                                debug("%s: no ACK from device\n", __func__);
                                return I2C_NACK;
                        }
                        if (trans_status & HSI2C_NO_DEV) {
                                debug("%s: no device\n", __func__);
                                return I2C_NOK;
                        }
                        if (trans_status & HSI2C_TRANS_ABORT) {
                                debug("%s: arbitration lost\n", __func__);
                                return I2C_NOK_LA;
                        }
                        if (trans_status & HSI2C_TIMEOUT_AUTO) {
                                debug("%s: device timed out\n", __func__);
                                return I2C_NOK_TOUT;
                        }
                        return I2C_OK;
                }
                udelay(1);
        }
        debug("%s: transaction timeout!\n", __func__);
        return I2C_NOK_TOUT;
}

static int hsi2c_get_clk_details(struct s3c24x0_i2c_bus *i2c_bus)
{
        struct exynos5_hsi2c *hsregs = i2c_bus->hsregs;
        ulong clkin;
        unsigned int op_clk = i2c_bus->clock_frequency;
        unsigned int i = 0, utemp0 = 0, utemp1 = 0;
        unsigned int t_ftl_cycle;

#if (defined CONFIG_EXYNOS4 || defined CONFIG_EXYNOS5)
        clkin = get_i2c_clk();
#else
        clkin = get_PCLK();
#endif
        /* FPCLK / FI2C =
         * (CLK_DIV + 1) * (TSCLK_L + TSCLK_H + 2) + 8 + 2 * FLT_CYCLE
         * uTemp0 = (CLK_DIV + 1) * (TSCLK_L + TSCLK_H + 2)
         * uTemp1 = (TSCLK_L + TSCLK_H + 2)
         * uTemp2 = TSCLK_L + TSCLK_H
         */
        t_ftl_cycle = (readl(&hsregs->usi_conf) >> 16) & 0x7;
        utemp0 = (clkin / op_clk) - 8 - 2 * t_ftl_cycle;

        /* CLK_DIV max is 256 */
        for (i = 0; i < 256; i++) {
                utemp1 = utemp0 / (i + 1);
                if ((utemp1 < 512) && (utemp1 > 4)) {
                        i2c_bus->clk_cycle = utemp1 - 2;
                        i2c_bus->clk_div = i;
                        return 0;
                }
        }
        return -EINVAL;
}

static void hsi2c_ch_init(struct s3c24x0_i2c_bus *i2c_bus)
{
        struct exynos5_hsi2c *hsregs = i2c_bus->hsregs;
        unsigned int t_sr_release;
        unsigned int n_clkdiv;
        unsigned int t_start_su, t_start_hd;
        unsigned int t_stop_su;
        unsigned int t_data_su, t_data_hd;
        unsigned int t_scl_l, t_scl_h;
        u32 i2c_timing_s1;
        u32 i2c_timing_s2;
        u32 i2c_timing_s3;
        u32 i2c_timing_sla;

        n_clkdiv = i2c_bus->clk_div;
        t_scl_l = i2c_bus->clk_cycle / 2;
        t_scl_h = i2c_bus->clk_cycle / 2;
        t_start_su = t_scl_l;
        t_start_hd = t_scl_l;
        t_stop_su = t_scl_l;
        t_data_su = t_scl_l / 2;
        t_data_hd = t_scl_l / 2;
        t_sr_release = i2c_bus->clk_cycle;

        i2c_timing_s1 = t_start_su << 24 | t_start_hd << 16 | t_stop_su << 8;
        i2c_timing_s2 = t_data_su << 24 | t_scl_l << 8 | t_scl_h << 0;
        i2c_timing_s3 = n_clkdiv << 16 | t_sr_release << 0;
        i2c_timing_sla = t_data_hd << 0;

        writel(HSI2C_TRAILING_COUNT, &hsregs->usi_trailing_ctl);

        /* Clear to enable Timeout */
        clrsetbits_le32(&hsregs->usi_timeout, HSI2C_TIMEOUT_EN, 0);

        /* set AUTO mode */
        writel(readl(&hsregs->usi_conf) | HSI2C_AUTO_MODE, &hsregs->usi_conf);

        /* Enable completion conditions' reporting. */
        writel(HSI2C_INT_I2C_EN, &hsregs->usi_int_en);

        /* Enable FIFOs */
        writel(HSI2C_RXFIFO_EN | HSI2C_TXFIFO_EN, &hsregs->usi_fifo_ctl);

        /* Currently operating in Fast speed mode. */
        writel(i2c_timing_s1, &hsregs->usi_timing_fs1);
        writel(i2c_timing_s2, &hsregs->usi_timing_fs2);
        writel(i2c_timing_s3, &hsregs->usi_timing_fs3);
        writel(i2c_timing_sla, &hsregs->usi_timing_sla);
}

/* SW reset for the high speed bus */
static void exynos5_i2c_reset(struct s3c24x0_i2c_bus *i2c_bus)
{
        struct exynos5_hsi2c *i2c = i2c_bus->hsregs;
        u32 i2c_ctl;

        /* Set and clear the bit for reset */
        i2c_ctl = readl(&i2c->usi_ctl);
        i2c_ctl |= HSI2C_SW_RST;
        writel(i2c_ctl, &i2c->usi_ctl);

        i2c_ctl = readl(&i2c->usi_ctl);
        i2c_ctl &= ~HSI2C_SW_RST;
        writel(i2c_ctl, &i2c->usi_ctl);

        /* Initialize the configure registers */
        hsi2c_ch_init(i2c_bus);
}

/*
 * Poll the appropriate bit of the fifo status register until the interface is
 * ready to process the next byte or timeout expires.
 *
 * In addition to the FIFO status register this function also polls the
 * interrupt status register to be able to detect unexpected transaction
 * completion.
 *
 * When FIFO is ready to process the next byte, this function returns I2C_OK.
 * If in course of polling the INT_I2C assertion is detected, the function
 * returns I2C_NOK. If timeout happens before any of the above conditions is
 * met - the function returns I2C_NOK_TOUT;

 * @param i2c: pointer to the appropriate i2c register bank.
 * @param rx_transfer: set to True if the receive transaction is in progress.
 * @return: as described above.
 */
static unsigned hsi2c_poll_fifo(struct exynos5_hsi2c *i2c, bool rx_transfer)
{
        u32 fifo_bit = rx_transfer ? HSI2C_RX_FIFO_EMPTY : HSI2C_TX_FIFO_FULL;
        int i = HSI2C_TIMEOUT_US;

        while (readl(&i2c->usi_fifo_stat) & fifo_bit) {
                if (readl(&i2c->usi_int_stat) & HSI2C_INT_I2C_EN) {
                        /*
                         * There is a chance that assertion of
                         * HSI2C_INT_I2C_EN and deassertion of
                         * HSI2C_RX_FIFO_EMPTY happen simultaneously. Let's
                         * give FIFO status priority and check it one more
                         * time before reporting interrupt. The interrupt will
                         * be reported next time this function is called.
                         */
                        if (rx_transfer &&
                            !(readl(&i2c->usi_fifo_stat) & fifo_bit))
                                break;
                        return I2C_NOK;
                }
                if (!i--) {
                        debug("%s: FIFO polling timeout!\n", __func__);
                        return I2C_NOK_TOUT;
                }
                udelay(1);
        }
        return I2C_OK;
}

/*
 * Preapre hsi2c transaction, either read or write.
 *
 * Set up transfer as described in section 27.5.1.2 'I2C Channel Auto Mode' of
 * the 5420 UM.
 *
 * @param i2c: pointer to the appropriate i2c register bank.
 * @param chip: slave address on the i2c bus (with read/write bit exlcuded)
 * @param len: number of bytes expected to be sent or received
 * @param rx_transfer: set to true for receive transactions
 * @param: issue_stop: set to true if i2c stop condition should be generated
 *         after this transaction.
 * @return: I2C_NOK_TOUT in case the bus remained busy for HSI2C_TIMEOUT_US,
 *          I2C_OK otherwise.
 */
static int hsi2c_prepare_transaction(struct exynos5_hsi2c *i2c,
                                     u8 chip,
                                     u16 len,
                                     bool rx_transfer,
                                     bool issue_stop)
{
        u32 conf;

        conf = len | HSI2C_MASTER_RUN;

        if (issue_stop)
                conf |= HSI2C_STOP_AFTER_TRANS;

        /* Clear to enable Timeout */
        writel(readl(&i2c->usi_timeout) & ~HSI2C_TIMEOUT_EN, &i2c->usi_timeout);

        /* Set slave address */
        writel(HSI2C_SLV_ADDR_MAS(chip), &i2c->i2c_addr);

        if (rx_transfer) {
                /* i2c master, read transaction */
                writel((HSI2C_RXCHON | HSI2C_FUNC_MODE_I2C | HSI2C_MASTER),
                       &i2c->usi_ctl);

                /* read up to len bytes, stop after transaction is finished */
                writel(conf | HSI2C_READ_WRITE, &i2c->usi_auto_conf);
        } else {
                /* i2c master, write transaction */
                writel((HSI2C_TXCHON | HSI2C_FUNC_MODE_I2C | HSI2C_MASTER),
                       &i2c->usi_ctl);

                /* write up to len bytes, stop after transaction is finished */
                writel(conf, &i2c->usi_auto_conf);
        }

        /* Reset all pending interrupt status bits we care about, if any */
        writel(HSI2C_INT_I2C_EN, &i2c->usi_int_stat);

        return I2C_OK;
}

/*
 * Wait while i2c bus is settling down (mostly stop gets completed).
 */
static int hsi2c_wait_while_busy(struct exynos5_hsi2c *i2c)
{
        int i = HSI2C_TIMEOUT_US;

        while (readl(&i2c->usi_trans_status) & HSI2C_MASTER_BUSY) {
                if (!i--) {
                        debug("%s: bus busy\n", __func__);
                        return I2C_NOK_TOUT;
                }
                udelay(1);
        }
        return I2C_OK;
}

static int hsi2c_write(struct exynos5_hsi2c *i2c,
                       unsigned char chip,
                       unsigned char addr[],
                       unsigned char alen,
                       unsigned char data[],
                       unsigned short len,
                       bool issue_stop)
{
        int i, rv = 0;

        if (!(len + alen)) {
                /* Writes of zero length not supported in auto mode. */
                debug("%s: zero length writes not supported\n", __func__);
                return I2C_NOK;
        }

        rv = hsi2c_prepare_transaction
                (i2c, chip, len + alen, false, issue_stop);
        if (rv != I2C_OK)
                return rv;

        /* Move address, if any, and the data, if any, into the FIFO. */
        for (i = 0; i < alen; i++) {
                rv = hsi2c_poll_fifo(i2c, false);
                if (rv != I2C_OK) {
                        debug("%s: address write failed\n", __func__);
                        goto write_error;
                }
                writel(addr[i], &i2c->usi_txdata);
        }

        for (i = 0; i < len; i++) {
                rv = hsi2c_poll_fifo(i2c, false);
                if (rv != I2C_OK) {
                        debug("%s: data write failed\n", __func__);
                        goto write_error;
                }
                writel(data[i], &i2c->usi_txdata);
        }

        rv = hsi2c_wait_for_trx(i2c);

 write_error:
        if (issue_stop) {
                int tmp_ret = hsi2c_wait_while_busy(i2c);
                if (rv == I2C_OK)
                        rv = tmp_ret;
        }

        writel(HSI2C_FUNC_MODE_I2C, &i2c->usi_ctl); /* done */
        return rv;
}

static int hsi2c_read(struct exynos5_hsi2c *i2c,
                      unsigned char chip,
                      unsigned char addr[],
                      unsigned char alen,
                      unsigned char data[],
                      unsigned short len)
{
        int i, rv, tmp_ret;
        bool drop_data = false;

        if (!len) {
                /* Reads of zero length not supported in auto mode. */
                debug("%s: zero length read adjusted\n", __func__);
                drop_data = true;
                len = 1;
        }

        if (alen) {
                /* Internal register adress needs to be written first. */
                rv = hsi2c_write(i2c, chip, addr, alen, NULL, 0, false);
                if (rv != I2C_OK)
                        return rv;
        }

        rv = hsi2c_prepare_transaction(i2c, chip, len, true, true);

        if (rv != I2C_OK)
                return rv;

        for (i = 0; i < len; i++) {
                rv = hsi2c_poll_fifo(i2c, true);
                if (rv != I2C_OK)
                        goto read_err;
                if (drop_data)
                        continue;
                data[i] = readl(&i2c->usi_rxdata);
        }

        rv = hsi2c_wait_for_trx(i2c);

 read_err:
        tmp_ret = hsi2c_wait_while_busy(i2c);
        if (rv == I2C_OK)
                rv = tmp_ret;

        writel(HSI2C_FUNC_MODE_I2C, &i2c->usi_ctl); /* done */
        return rv;
}

static int exynos_hs_i2c_xfer(struct udevice *dev, struct i2c_msg *msg,
                              int nmsgs)
{
        struct s3c24x0_i2c_bus *i2c_bus = dev_get_priv(dev);
        struct exynos5_hsi2c *hsregs = i2c_bus->hsregs;
        int ret;

        for (; nmsgs > 0; nmsgs--, msg++) {
                if (msg->flags & I2C_M_RD) {
                        ret = hsi2c_read(hsregs, msg->addr, 0, 0, msg->buf,
                                         msg->len);
                } else {
                        ret = hsi2c_write(hsregs, msg->addr, 0, 0, msg->buf,
                                          msg->len, true);
                }
                if (ret) {
                        exynos5_i2c_reset(i2c_bus);
                        return -EREMOTEIO;
                }
        }

        return 0;
}

static int s3c24x0_i2c_set_bus_speed(struct udevice *dev, unsigned int speed)
{
        struct s3c24x0_i2c_bus *i2c_bus = dev_get_priv(dev);

        i2c_bus->clock_frequency = speed;

        if (hsi2c_get_clk_details(i2c_bus))
                return -EFAULT;
        hsi2c_ch_init(i2c_bus);

        return 0;
}

static int s3c24x0_i2c_probe(struct udevice *dev, uint chip, uint chip_flags)
{
        struct s3c24x0_i2c_bus *i2c_bus = dev_get_priv(dev);
        uchar buf[1];
        int ret;

        buf[0] = 0;

        /*
         * What is needed is to send the chip address and verify that the
         * address was <ACK>ed (i.e. there was a chip at that address which
         * drove the data line low).
         */
        ret = hsi2c_read(i2c_bus->hsregs, chip, 0, 0, buf, 1);

        return ret != I2C_OK;
}

static int s3c_i2c_of_to_plat(struct udevice *dev)
{
        const void *blob = gd->fdt_blob;
        struct s3c24x0_i2c_bus *i2c_bus = dev_get_priv(dev);
        int node;

        node = dev_of_offset(dev);

        i2c_bus->hsregs = dev_read_addr_ptr(dev);

        i2c_bus->id = pinmux_decode_periph_id(blob, node);

        i2c_bus->clock_frequency =
                dev_read_u32_default(dev, "clock-frequency",
                                     I2C_SPEED_STANDARD_RATE);
        i2c_bus->node = node;
        i2c_bus->bus_num = dev_seq(dev);

        exynos_pinmux_config(i2c_bus->id, PINMUX_FLAG_HS_MODE);

        i2c_bus->active = true;

        return 0;
}

static const struct dm_i2c_ops exynos_hs_i2c_ops = {
        .xfer           = exynos_hs_i2c_xfer,
        .probe_chip     = s3c24x0_i2c_probe,
        .set_bus_speed  = s3c24x0_i2c_set_bus_speed,
};

static const struct udevice_id exynos_hs_i2c_ids[] = {
        { .compatible = "samsung,exynos5-hsi2c" },
        { }
};

U_BOOT_DRIVER(hs_i2c) = {
        .name   = "i2c_s3c_hs",
        .id     = UCLASS_I2C,
        .of_match = exynos_hs_i2c_ids,
        .of_to_plat = s3c_i2c_of_to_plat,
        .priv_auto      = sizeof(struct s3c24x0_i2c_bus),
        .ops    = &exynos_hs_i2c_ops,
};