/*
 * (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>
#include <errno.h>
#include <amlogic/i2c.h>

#define MESON_I2C_CLK_RATE  166666667

#define BIT(nr)         (1UL << (nr))
#define GENMASK(h, l) \
(((~0UL) << (l)) & (~0UL >> (BITS_PER_LONG - 1 - (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 */
	uint clock_frequency;
	uint div_factor;
	uint delay_adjust;
};

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;

	clrsetbits_le32(&i2c->regs->slave_addr, GENMASK(7, 0),
					(msg->addr << 1) & GENMASK(7, 0));
	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 %x 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;
}

/*
 * Count = clk/freq  = H + L
 * Duty  = H/(H + L) = 1/2	-- duty 50%
 * 1. register description
 * in I2C_CONTROL_REG , n = [28:29][21:12], control the high level time
 *			n consists of 12bit, [21:12] is the low 10bit,
 *			[28:29] is the bit 11 and 12.
 * in I2C_SLAVE_ADDRESS, m = [27:16], control the low level time,
 *			 bit 28 enable the function
 *
 * 2.I2C controller internal characteristic
 * H = n + delay
 * L = 2m
 * (H:high clock counts equals n + 15 clocks which
 *    cost by sampling and filtering
 *  L:low clock counts equals m multiply by 2)
 *
 * 3.high level and low level relationship:
 * H/L = (n + 15)/2m = 1/1
 * H+L = 2m + n +15 = Count
 * Count = 166M/freq = 166M/100k
 *
 * =>
 *
 * n = Count/2 - delay
 * m = Count/4
 *
 * n equals div_h, m equals div_l below
 * Standard Mode : 100k
 */
static int meson_i2c_set_std_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_h, div_l;
	unsigned int div_temp;

	div_temp = DIV_ROUND_UP(clk_rate, speed);
	div_h = DIV_ROUND_UP(div_temp, 2) - i2c->delay_adjust;
	div_l = DIV_ROUND_UP(div_temp, 4);

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

	if (div_l >= (1 << 12)) {
		debug("requested bus frequency too low\n");
		div_l = (1 << 12) - 1;
	}

	/*control reg:12-21 bits*/
	clrsetbits_le32(&i2c->regs->ctrl, REG_CTRL_CLKDIV_MASK,
			(div_h & GENMASK(9, 0)) << REG_CTRL_CLKDIV_SHIFT);

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

	/* set SCL low delay */
	clrsetbits_le32(&i2c->regs->slave_addr, GENMASK(27, 16),
					(div_l << 16) & GENMASK(27, 16));

	/* enable to control SCL low time */
	clrsetbits_le32(&i2c->regs->slave_addr, BIT(28), BIT(28));

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

	return 0;
}

/*
 * Duty  = H/(H + L) = 2/5	-- duty 40%%   H/L = 2/3
 * Refer to meson_i2c_set_std_speed note.
 * Fast Mode : 400k
 * High Mode : 3400k
 */
static int meson_i2c_set_fast_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_h, div_l;
	unsigned int div_temp;

	div_temp = DIV_ROUND_UP(clk_rate * 2, speed * 5);
	div_h = div_temp - i2c->delay_adjust;
	div_l = DIV_ROUND_UP(clk_rate * 3, speed * 10);

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

	if (div_l >= (1 << 12)) {
		debug("requested bus frequency too low\n");
		div_l = (1 << 12) - 1;
	}

	/*control reg:12-21 bits*/
	clrsetbits_le32(&i2c->regs->ctrl, REG_CTRL_CLKDIV_MASK,
			(div_h & GENMASK(9, 0)) << REG_CTRL_CLKDIV_SHIFT);

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


	/* set SCL low delay */
	clrsetbits_le32(&i2c->regs->slave_addr, GENMASK(27, 16),
					(div_l << 16) & GENMASK(27, 16));

	/* enable to control SCL low time */
	clrsetbits_le32(&i2c->regs->slave_addr, BIT(28), BIT(28));

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

	return 0;
}

static int meson_i2c_set_bus_speed(struct udevice *bus, unsigned int speed)
{
	if (speed >= 400000)
		meson_i2c_set_fast_speed(bus, speed);
	else
		meson_i2c_set_std_speed(bus, speed);

	return 0;
}

static int meson_i2c_probe(struct udevice *bus)
{
	struct meson_i2c *i2c = dev_get_priv(bus);
	struct meson_i2c_platdata *plat = dev_get_platdata(bus);
	unsigned int i;

	debug("index = %d, reg = 0x%lx, rate = %d, div = %d, delay = %d, clock-frequency = %d\n",
		plat->i2c_index, plat->reg,
		plat->clock_rate, plat->div_factor, plat->delay_adjust,
		plat->clock_frequency);

	i2c->regs = (struct i2c_regs *)plat->reg;
	i2c->div_factor = plat->div_factor;
	i2c->delay_adjust = plat->delay_adjust;
	i2c->clock_frequency = plat->clock_frequency;
	bus->priv = i2c;

	/* init i2c REGs */
	for (i = 0; i < 8;i++)
		writel(0, &i2c->regs->ctrl + i);

	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,
};

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

U_BOOT_DRIVER(i2c_meson) = {
	.name = "i2c_meson",
	.id   = UCLASS_I2C,
#ifdef CONFIG_OF_CONTROL
	.of_match = meson_i2c_ids,
#endif
	.probe = meson_i2c_probe,
	.priv_auto_alloc_size = sizeof(struct meson_i2c),
	.ops = &meson_i2c_ops,
	.per_child_auto_alloc_size = sizeof (struct meson_i2c_slavedata),
};