/*
 * (C) Copyright 2017 - Beniamino Galvani <b.galvani@gmail.com>
 *
 * SPDX-License-Identifier:     GPL-2.0+
 */
#include <common.h>
#include <asm/arch/i2c.h>
#include <asm/io.h>
#include <dm.h>
#include <i2c.h>

#define I2C_TIMEOUT_MS          100

/* Control register fields */
#define REG_CTRL_START          BIT(0)
#define REG_CTRL_ACK_IGNORE     BIT(1)
#define REG_CTRL_STATUS         BIT(2)
#define REG_CTRL_ERROR          BIT(3)
#define REG_CTRL_CLKDIV_SHIFT   12
#define REG_CTRL_CLKDIV_MASK    GENMASK(21, 12)
#define REG_CTRL_CLKDIVEXT_SHIFT 28
#define REG_CTRL_CLKDIVEXT_MASK GENMASK(29, 28)

enum {
        TOKEN_END = 0,
        TOKEN_START,
        TOKEN_SLAVE_ADDR_WRITE,
        TOKEN_SLAVE_ADDR_READ,
        TOKEN_DATA,
        TOKEN_DATA_LAST,
        TOKEN_STOP,
};

struct i2c_regs {
        u32 ctrl;
        u32 slave_addr;
        u32 tok_list0;
        u32 tok_list1;
        u32 tok_wdata0;
        u32 tok_wdata1;
        u32 tok_rdata0;
        u32 tok_rdata1;
};

struct meson_i2c {
        struct i2c_regs *regs;
        struct i2c_msg *msg;    /* Current I2C message */
        bool last;              /* Whether the message is the last */
        uint count;             /* Number of bytes in the current transfer */
        uint pos;               /* Position of current transfer in message */
        u32 tokens[2];          /* Sequence of tokens to be written */
        uint num_tokens;        /* Number of tokens to be written */
};

static void meson_i2c_reset_tokens(struct meson_i2c *i2c)
{
        i2c->tokens[0] = 0;
        i2c->tokens[1] = 0;
        i2c->num_tokens = 0;
}

static void meson_i2c_add_token(struct meson_i2c *i2c, int token)
{
        if (i2c->num_tokens < 8)
                i2c->tokens[0] |= (token & 0xf) << (i2c->num_tokens * 4);
        else
                i2c->tokens[1] |= (token & 0xf) << ((i2c->num_tokens % 8) * 4);

        i2c->num_tokens++;
}

/*
 * Retrieve data for the current transfer (which can be at most 8
 * bytes) from the device internal buffer.
 */
static void meson_i2c_get_data(struct meson_i2c *i2c, u8 *buf, int len)
{
        u32 rdata0, rdata1;
        int i;

        rdata0 = readl(&i2c->regs->tok_rdata0);
        rdata1 = readl(&i2c->regs->tok_rdata1);

        debug("meson i2c: read data %08x %08x len %d\n", rdata0, rdata1, len);

        for (i = 0; i < min(4, len); i++)
                *buf++ = (rdata0 >> i * 8) & 0xff;

        for (i = 4; i < min(8, len); i++)
                *buf++ = (rdata1 >> (i - 4) * 8) & 0xff;
}

/*
 * Write data for the current transfer (which can be at most 8 bytes)
 * to the device internal buffer.
 */
static void meson_i2c_put_data(struct meson_i2c *i2c, u8 *buf, int len)
{
        u32 wdata0 = 0, wdata1 = 0;
        int i;

        for (i = 0; i < min(4, len); i++)
                wdata0 |= *buf++ << (i * 8);

        for (i = 4; i < min(8, len); i++)
                wdata1 |= *buf++ << ((i - 4) * 8);

        writel(wdata0, &i2c->regs->tok_wdata0);
        writel(wdata1, &i2c->regs->tok_wdata1);

        debug("meson i2c: write data %08x %08x len %d\n", wdata0, wdata1, len);
}

/*
 * Prepare the next transfer: pick the next 8 bytes in the remaining
 * part of message and write tokens and data (if needed) to the
 * device.
 */
static void meson_i2c_prepare_xfer(struct meson_i2c *i2c)
{
        bool write = !(i2c->msg->flags & I2C_M_RD);
        int i;

        i2c->count = min(i2c->msg->len - i2c->pos, 8u);

        for (i = 0; i + 1 < i2c->count; i++)
                meson_i2c_add_token(i2c, TOKEN_DATA);

        if (i2c->count) {
                if (write || i2c->pos + i2c->count < i2c->msg->len)
                        meson_i2c_add_token(i2c, TOKEN_DATA);
                else
                        meson_i2c_add_token(i2c, TOKEN_DATA_LAST);
        }

        if (write)
                meson_i2c_put_data(i2c, i2c->msg->buf + i2c->pos, i2c->count);

        if (i2c->last && i2c->pos + i2c->count >= i2c->msg->len)
                meson_i2c_add_token(i2c, TOKEN_STOP);

        writel(i2c->tokens[0], &i2c->regs->tok_list0);
        writel(i2c->tokens[1], &i2c->regs->tok_list1);
}

static void meson_i2c_do_start(struct meson_i2c *i2c, struct i2c_msg *msg)
{
        int token;

        token = (msg->flags & I2C_M_RD) ? TOKEN_SLAVE_ADDR_READ :
                TOKEN_SLAVE_ADDR_WRITE;

        writel(msg->addr << 1, &i2c->regs->slave_addr);
        meson_i2c_add_token(i2c, TOKEN_START);
        meson_i2c_add_token(i2c, token);
}

static int meson_i2c_xfer_msg(struct meson_i2c *i2c, struct i2c_msg *msg,
                              int last)
{
        ulong start;

        debug("meson i2c: %s addr %u len %u\n",
              (msg->flags & I2C_M_RD) ? "read" : "write",
              msg->addr, msg->len);

        i2c->msg = msg;
        i2c->last = last;
        i2c->pos = 0;
        i2c->count = 0;

        meson_i2c_reset_tokens(i2c);
        meson_i2c_do_start(i2c, msg);

        do {
                meson_i2c_prepare_xfer(i2c);

                /* start the transfer */
                setbits_le32(&i2c->regs->ctrl, REG_CTRL_START);
                start = get_timer(0);
                while (readl(&i2c->regs->ctrl) & REG_CTRL_STATUS) {
                        if (get_timer(start) > I2C_TIMEOUT_MS) {
                                clrbits_le32(&i2c->regs->ctrl, REG_CTRL_START);
                                debug("meson i2c: timeout\n");
                                return -ETIMEDOUT;
                        }
                        udelay(1);
                }
                meson_i2c_reset_tokens(i2c);
                clrbits_le32(&i2c->regs->ctrl, REG_CTRL_START);

                if (readl(&i2c->regs->ctrl) & REG_CTRL_ERROR) {
                        debug("meson i2c: error\n");
                        return -EREMOTEIO;
                }

                if ((msg->flags & I2C_M_RD) && i2c->count) {
                        meson_i2c_get_data(i2c, i2c->msg->buf + i2c->pos,
                                           i2c->count);
                }
                i2c->pos += i2c->count;
        } while (i2c->pos < msg->len);

        return 0;
}

static int meson_i2c_xfer(struct udevice *bus, struct i2c_msg *msg,
                          int nmsgs)
{
        struct meson_i2c *i2c = dev_get_priv(bus);
        int i, ret = 0;

        for (i = 0; i < nmsgs; i++) {
                ret = meson_i2c_xfer_msg(i2c, msg + i, i == nmsgs - 1);
                if (ret)
                        return ret;
        }

        return 0;
}

static int meson_i2c_set_bus_speed(struct udevice *bus, unsigned int speed)
{
        struct meson_i2c *i2c = dev_get_priv(bus);
        unsigned int clk_rate = MESON_I2C_CLK_RATE;
        unsigned int div;

        div = DIV_ROUND_UP(clk_rate, speed * 4);

        /* clock divider has 12 bits */
        if (div >= (1 << 12)) {
                debug("meson i2c: requested bus frequency too low\n");
                div = (1 << 12) - 1;
        }

        clrsetbits_le32(&i2c->regs->ctrl, REG_CTRL_CLKDIV_MASK,
                        (div & GENMASK(9, 0)) << REG_CTRL_CLKDIV_SHIFT);

        clrsetbits_le32(&i2c->regs->ctrl, REG_CTRL_CLKDIVEXT_MASK,
                        (div >> 10) << REG_CTRL_CLKDIVEXT_SHIFT);

        debug("meson i2c: set clk %u, src %u, div %u\n", speed, clk_rate, div);

        return 0;
}

static int meson_i2c_probe(struct udevice *bus)
{
        struct meson_i2c *i2c = dev_get_priv(bus);

        i2c->regs = dev_read_addr_ptr(bus);
        clrbits_le32(&i2c->regs->ctrl, REG_CTRL_START);

        return 0;
}

static const struct dm_i2c_ops meson_i2c_ops = {
        .xfer          = meson_i2c_xfer,
        .set_bus_speed = meson_i2c_set_bus_speed,
};

static const struct udevice_id meson_i2c_ids[] = {
        { .compatible = "amlogic,meson6-i2c" },
        { .compatible = "amlogic,meson-gx-i2c" },
        { .compatible = "amlogic,meson-gxbb-i2c" },
        { }
};

U_BOOT_DRIVER(i2c_meson) = {
        .name = "i2c_meson",
        .id   = UCLASS_I2C,
        .of_match = meson_i2c_ids,
        .probe = meson_i2c_probe,
        .priv_auto_alloc_size = sizeof(struct meson_i2c),
        .ops = &meson_i2c_ops,
};