// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (C) 2014      Panasonic Corporation
 * Copyright (C) 2015-2016 Socionext Inc.
 *   Author: Masahiro Yamada <yamada.masahiro@socionext.com>
 */

#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/io.h>
#include <linux/sizes.h>
#include <linux/types.h>
#include <dm.h>
#include <fdtdec.h>
#include <i2c.h>

struct uniphier_i2c_regs {
        u32 dtrm;                       /* data transmission */
#define I2C_DTRM_STA    (1 << 10)
#define I2C_DTRM_STO    (1 << 9)
#define I2C_DTRM_NACK   (1 << 8)
#define I2C_DTRM_RD     (1 << 0)
        u32 drec;                       /* data reception */
#define I2C_DREC_STS    (1 << 12)
#define I2C_DREC_LRB    (1 << 11)
#define I2C_DREC_LAB    (1 << 9)
        u32 myad;                       /* slave address */
        u32 clk;                        /* clock frequency control */
        u32 brst;                       /* bus reset */
#define I2C_BRST_FOEN   (1 << 1)
#define I2C_BRST_BRST   (1 << 0)
        u32 hold;                       /* hold time control */
        u32 bsts;                       /* bus status monitor */
        u32 noise;                      /* noise filter control */
        u32 setup;                      /* setup time control */
};

#define IOBUS_FREQ      100000000

struct uniphier_i2c_priv {
        struct udevice *dev;
        struct uniphier_i2c_regs __iomem *regs; /* register base */
        unsigned long input_clk;        /* master clock (Hz) */
        unsigned long wait_us;          /* wait for every byte transfer (us) */
};

static int uniphier_i2c_probe(struct udevice *dev)
{
        fdt_addr_t addr;
        struct uniphier_i2c_priv *priv = dev_get_priv(dev);

        addr = devfdt_get_addr(dev);
        if (addr == FDT_ADDR_T_NONE)
                return -EINVAL;

        priv->regs = devm_ioremap(dev, addr, SZ_64);
        if (!priv->regs)
                return -ENOMEM;

        priv->input_clk = IOBUS_FREQ;

        priv->dev = dev;

        /* deassert reset */
        writel(0x3, &priv->regs->brst);

        return 0;
}

static int send_and_recv_byte(struct uniphier_i2c_priv *priv, u32 dtrm)
{
        writel(dtrm, &priv->regs->dtrm);

        /*
         * This controller only provides interruption to inform the completion
         * of each byte transfer.  (No status register to poll it.)
         * Unfortunately, U-Boot does not have a good support of interrupt.
         * Wait for a while.
         */
        udelay(priv->wait_us);

        return readl(&priv->regs->drec);
}

static int send_byte(struct uniphier_i2c_priv *priv, u32 dtrm, bool *stop)
{
        int ret = 0;
        u32 drec;

        drec = send_and_recv_byte(priv, dtrm);

        if (drec & I2C_DREC_LAB) {
                dev_dbg(priv->dev, "uniphier_i2c: bus arbitration failed\n");
                *stop = false;
                ret = -EREMOTEIO;
        }
        if (drec & I2C_DREC_LRB) {
                dev_dbg(priv->dev, "uniphier_i2c: slave did not return ACK\n");
                ret = -EREMOTEIO;
        }
        return ret;
}

static int uniphier_i2c_transmit(struct uniphier_i2c_priv *priv, uint addr,
                                 uint len, const u8 *buf, bool *stop)
{
        int ret;

        dev_dbg(priv->dev, "%s: addr = %x, len = %d\n", __func__, addr, len);

        ret = send_byte(priv, I2C_DTRM_STA | I2C_DTRM_NACK | addr << 1, stop);
        if (ret < 0)
                goto fail;

        while (len--) {
                ret = send_byte(priv, I2C_DTRM_NACK | *buf++, stop);
                if (ret < 0)
                        goto fail;
        }

fail:
        if (*stop)
                writel(I2C_DTRM_STO | I2C_DTRM_NACK, &priv->regs->dtrm);

        return ret;
}

static int uniphier_i2c_receive(struct uniphier_i2c_priv *priv, uint addr,
                                uint len, u8 *buf, bool *stop)
{
        int ret;

        dev_dbg(priv->dev, "%s: addr = %x, len = %d\n", __func__, addr, len);

        ret = send_byte(priv, I2C_DTRM_STA | I2C_DTRM_NACK |
                        I2C_DTRM_RD | addr << 1, stop);
        if (ret < 0)
                goto fail;

        while (len--)
                *buf++ = send_and_recv_byte(priv, len ? 0 : I2C_DTRM_NACK);

fail:
        if (*stop)
                writel(I2C_DTRM_STO | I2C_DTRM_NACK, &priv->regs->dtrm);

        return ret;
}

static int uniphier_i2c_xfer(struct udevice *bus, struct i2c_msg *msg,
                             int nmsgs)
{
        int ret = 0;
        struct uniphier_i2c_priv *priv = dev_get_priv(bus);
        bool stop;

        for (; nmsgs > 0; nmsgs--, msg++) {
                /* If next message is read, skip the stop condition */
                stop = nmsgs > 1 && msg[1].flags & I2C_M_RD ? false : true;

                if (msg->flags & I2C_M_RD)
                        ret = uniphier_i2c_receive(priv, msg->addr, msg->len,
                                                   msg->buf, &stop);
                else
                        ret = uniphier_i2c_transmit(priv, msg->addr, msg->len,
                                                    msg->buf, &stop);

                if (ret < 0)
                        break;
        }

        return ret;
}

static int uniphier_i2c_set_bus_speed(struct udevice *bus, unsigned int speed)
{
        struct uniphier_i2c_priv *priv = dev_get_priv(bus);

        /* max supported frequency is 400 kHz */
        if (speed > 400000)
                return -EINVAL;

        /* bus reset: make sure the bus is idle when change the frequency */
        writel(0x1, &priv->regs->brst);

        writel((priv->input_clk / speed / 2 << 16) | (priv->input_clk / speed),
               &priv->regs->clk);

        writel(0x3, &priv->regs->brst);

        /*
         * Theoretically, each byte can be transferred in
         * 1000000 * 9 / speed usec.  For safety, wait more than double.
         */
        priv->wait_us = 20000000 / speed;

        return 0;
}


static const struct dm_i2c_ops uniphier_i2c_ops = {
        .xfer = uniphier_i2c_xfer,
        .set_bus_speed = uniphier_i2c_set_bus_speed,
};

static const struct udevice_id uniphier_i2c_of_match[] = {
        { .compatible = "socionext,uniphier-i2c" },
        { /* sentinel */ }
};

U_BOOT_DRIVER(uniphier_i2c) = {
        .name = "uniphier-i2c",
        .id = UCLASS_I2C,
        .of_match = uniphier_i2c_of_match,
        .probe = uniphier_i2c_probe,
        .priv_auto_alloc_size = sizeof(struct uniphier_i2c_priv),
        .ops = &uniphier_i2c_ops,
};