/*
 * Copyright (c) 2011 The Chromium OS Authors.
 * (C) Copyright 2010,2011 NVIDIA Corporation <www.nvidia.com>
 *
 * SPDX-License-Identifier:     GPL-2.0+
 */

#include <common.h>
#include <tps6586x.h>
#include <asm/io.h>
#include <i2c.h>

static struct udevice *tps6586x_dev;

enum {
        /* Registers that we access */
        SUPPLY_CONTROL1         = 0x20,
        SUPPLY_CONTROL2,
        SM1_VOLTAGE_V1          = 0x23,
        SM1_VOLTAGE_V2,
        SM0_VOLTAGE_V1          = 0x26,
        SM0_VOLTAGE_V2,
        PFM_MODE                = 0x47,

        /* Bits in the supply control registers */
        CTRL_SM1_RAMP           = 0x01,
        CTRL_SM1_SUPPLY2        = 0x02,
        CTRL_SM0_RAMP           = 0x04,
        CTRL_SM0_SUPPLY2        = 0x08,
};

#define MAX_I2C_RETRY   3
static int tps6586x_read(int reg)
{
        int     i;
        uchar   data;
        int     retval = -1;

        for (i = 0; i < MAX_I2C_RETRY; ++i) {
                if (!dm_i2c_read(tps6586x_dev, reg,  &data, 1)) {
                        retval = (int)data;
                        goto exit;
                }

                /* i2c access failed, retry */
                udelay(100);
        }

exit:
        debug("pmu_read %x=%x\n", reg, retval);
        if (retval < 0)
                debug("%s: failed to read register %#x: %d\n", __func__, reg,
                      retval);
        return retval;
}

static int tps6586x_write(int reg, uchar *data, uint len)
{
        int     i;
        int     retval = -1;

        for (i = 0; i < MAX_I2C_RETRY; ++i) {
                if (!dm_i2c_write(tps6586x_dev, reg, data, len)) {
                        retval = 0;
                        goto exit;
                }

                /* i2c access failed, retry */
                udelay(100);
        }

exit:
        debug("pmu_write %x=%x: ", reg, retval);
        for (i = 0; i < len; i++)
                debug("%x ", data[i]);
        if (retval)
                debug("%s: failed to write register %#x\n", __func__, reg);
        return retval;
}

/*
 * Get current voltage of SM0 and SM1
 *
 * @param sm0   Place to put SM0 voltage
 * @param sm1   Place to put SM1 voltage
 * @return 0 if ok, -1 on error
 */
static int read_voltages(int *sm0, int *sm1)
{
        int ctrl1, ctrl2;
        int is_v2;

        /*
         * Each vdd has two supply sources, ie, v1 and v2.
         * The supply control reg1 and reg2 determine the current selection.
         */
        ctrl1 = tps6586x_read(SUPPLY_CONTROL1);
        ctrl2 = tps6586x_read(SUPPLY_CONTROL2);
        if (ctrl1 == -1 || ctrl2 == -1)
                return -1;

        /* Figure out whether V1 or V2 is selected */
        is_v2 = (ctrl1 | ctrl2) & CTRL_SM0_SUPPLY2;
        *sm0 = tps6586x_read(is_v2 ? SM0_VOLTAGE_V2 : SM0_VOLTAGE_V1);
        *sm1 = tps6586x_read(is_v2 ? SM1_VOLTAGE_V2 : SM1_VOLTAGE_V1);
        if (*sm0 == -1 || *sm1 == -1)
                return -1;

        return 0;
}

static int set_voltage(int reg, int data, int rate)
{
        uchar control_bit;
        uchar buff[3];

        control_bit = (reg == SM0_VOLTAGE_V1 ? CTRL_SM0_RAMP : CTRL_SM1_RAMP);

        /*
         * Only one supply is needed in u-boot. set both v1 and v2 to
         * same value.
         *
         * When both v1 and v2 are set to same value, we just need to set
         * control1 reg to trigger the supply selection.
         */
        buff[0] = buff[1] = (uchar)data;
        buff[2] = rate;

        /* write v1, v2 and rate, then trigger */
        if (tps6586x_write(reg, buff, 3) ||
            tps6586x_write(SUPPLY_CONTROL1, &control_bit, 1))
                return -1;

        return 0;
}

static int calculate_next_voltage(int voltage, int target, int step)
{
        int diff = voltage < target ? step : -step;

        if (abs(target - voltage) > step)
                voltage += diff;
        else
                voltage = target;

        return voltage;
}

int tps6586x_set_pwm_mode(int mask)
{
        uchar val;
        int ret;

        assert(tps6586x_dev);
        ret = tps6586x_read(PFM_MODE);
        if (ret != -1) {
                val = (uchar)ret;
                val |= mask;

                ret = tps6586x_write(PFM_MODE, &val, 1);
        }

        if (ret == -1)
                debug("%s: Failed to read/write PWM mode reg\n", __func__);

        return ret;
}

int tps6586x_adjust_sm0_sm1(int sm0_target, int sm1_target, int step, int rate,
                            int min_sm0_over_sm1)
{
        int sm0, sm1;
        int bad;

        assert(tps6586x_dev);

        /* get current voltage settings */
        if (read_voltages(&sm0, &sm1)) {
                debug("%s: Cannot read voltage settings\n", __func__);
                return -1;
        }

        /*
         * if vdd_core < vdd_cpu + rel
         *    skip
         *
         * This condition may happen when system reboots due to kernel crash.
         */
        if (min_sm0_over_sm1 != -1 && sm0 < sm1 + min_sm0_over_sm1) {
                debug("%s: SM0 is %d, SM1 is %d, but min_sm0_over_sm1 is %d\n",
                      __func__, sm0, sm1, min_sm0_over_sm1);
                return -1;
        }

        /*
         * Since vdd_core and vdd_cpu may both stand at either greater or less
         * than their nominal voltage, the adjustment may go either directions.
         *
         * Make sure vdd_core is always higher than vdd_cpu with certain margin.
         * So, find out which vdd to adjust first in each step.
         *
         * case 1: both sm0 and sm1 need to move up
         *              adjust sm0 before sm1
         *
         * case 2: both sm0 and sm1 need to move down
         *              adjust sm1 before sm0
         *
         * case 3: sm0 moves down and sm1 moves up
         *              adjusting either one first is fine.
         *
         * Adjust vdd_core and vdd_cpu one step at a time until they reach
         * their nominal values.
         */
        bad = 0;
        while (!bad && (sm0 != sm0_target || sm1 != sm1_target)) {
                int adjust_sm0_late = 0; /* flag to adjust vdd_core later */

                debug("%d-%d   %d-%d   ", sm0, sm0_target, sm1, sm1_target);

                if (sm0 != sm0_target) {
                        /*
                         * if case 1 and case 3, set new sm0 first.
                         * otherwise, hold down until new sm1 is set.
                         */
                        sm0 = calculate_next_voltage(sm0, sm0_target, step);
                        if (sm1 < sm1_target)
                                bad |= set_voltage(SM0_VOLTAGE_V1, sm0, rate);
                        else
                                adjust_sm0_late = 1;
                }

                if (sm1 != sm1_target) {
                        sm1 = calculate_next_voltage(sm1, sm1_target, step);
                        bad |= set_voltage(SM1_VOLTAGE_V1, sm1, rate);
                }

                if (adjust_sm0_late)
                        bad |= set_voltage(SM0_VOLTAGE_V1, sm0, rate);
                debug("%d\n", adjust_sm0_late);
        }
        debug("%d-%d   %d-%d   done\n", sm0, sm0_target, sm1, sm1_target);

        return bad ? -1 : 0;
}

int tps6586x_init(struct udevice *dev)
{
        tps6586x_dev = dev;

        return 0;
}