/*
 * Regulator driver for tps65090 power management chip.
 *
 * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.

 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.

 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.

 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>
 */

#include <linux/module.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/gpio.h>
#include <linux/of_gpio.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/platform_device.h>
#include <linux/regulator/driver.h>
#include <linux/regulator/machine.h>
#include <linux/regulator/of_regulator.h>
#include <linux/mfd/tps65090.h>

#define MAX_CTRL_READ_TRIES     5
#define MAX_FET_ENABLE_TRIES    1000

#define CTRL_EN_BIT             0 /* Regulator enable bit, active high */
#define CTRL_WT_BIT             2 /* Regulator wait time 0 bit */
#define CTRL_PG_BIT             4 /* Regulator power good bit, 1=good */
#define CTRL_TO_BIT             7 /* Regulator timeout bit, 1=wait */

#define MAX_OVERCURRENT_WAIT    3 /* Overcurrent wait must be <= this */

/**
 * struct tps65090_regulator - Per-regulator data for a tps65090 regulator
 *
 * @dev: Pointer to our device.
 * @desc: The struct regulator_desc for the regulator.
 * @rdev: The struct regulator_dev for the regulator.
 * @overcurrent_wait_valid: True if overcurrent_wait is valid.
 * @overcurrent_wait: For FETs, the value to put in the WTFET bitfield.
 */

struct tps65090_regulator {
        struct device           *dev;
        struct regulator_desc   *desc;
        struct regulator_dev    *rdev;
        bool                    overcurrent_wait_valid;
        int                     overcurrent_wait;
};

static struct regulator_ops tps65090_ext_control_ops = {
};

/**
 * tps65090_reg_set_overcurrent_wait - Setup overcurrent wait
 *
 * This will set the overcurrent wait time based on what's in the regulator
 * info.
 *
 * @ri:         Overall regulator data
 * @rdev:       Regulator device
 *
 * Return: 0 if no error, non-zero if there was an error writing the register.
 */
static int tps65090_reg_set_overcurrent_wait(struct tps65090_regulator *ri,
                                             struct regulator_dev *rdev)
{
        int ret;

        ret = regmap_update_bits(rdev->regmap, rdev->desc->enable_reg,
                                 MAX_OVERCURRENT_WAIT << CTRL_WT_BIT,
                                 ri->overcurrent_wait << CTRL_WT_BIT);
        if (ret) {
                dev_err(&rdev->dev, "Error updating overcurrent wait %#x\n",
                        rdev->desc->enable_reg);
        }

        return ret;
}

/**
 * tps65090_try_enable_fet - Try to enable a FET
 *
 * @rdev:       Regulator device
 *
 * Return: 0 if ok, -ENOTRECOVERABLE if the FET power good bit did not get
 * set, or some other -ve value if another error occurred (e.g. i2c error)
 */
static int tps65090_try_enable_fet(struct regulator_dev *rdev)
{
        unsigned int control;
        int ret, i;

        ret = regmap_update_bits(rdev->regmap, rdev->desc->enable_reg,
                                 rdev->desc->enable_mask,
                                 rdev->desc->enable_mask);
        if (ret < 0) {
                dev_err(&rdev->dev, "Error in updating reg %#x\n",
                        rdev->desc->enable_reg);
                return ret;
        }

        for (i = 0; i < MAX_CTRL_READ_TRIES; i++) {
                ret = regmap_read(rdev->regmap, rdev->desc->enable_reg,
                                  &control);
                if (ret < 0)
                        return ret;

                if (!(control & BIT(CTRL_TO_BIT)))
                        break;

                usleep_range(1000, 1500);
        }
        if (!(control & BIT(CTRL_PG_BIT)))
                return -ENOTRECOVERABLE;

        return 0;
}

/**
 * tps65090_fet_enable - Enable a FET, trying a few times if it fails
 *
 * Some versions of the tps65090 have issues when turning on the FETs.
 * This function goes through several steps to ensure the best chance of the
 * FET going on.  Specifically:
 * - We'll make sure that we bump the "overcurrent wait" to the maximum, which
 *   increases the chances that we'll turn on properly.
 * - We'll retry turning the FET on multiple times (turning off in between).
 *
 * @rdev:       Regulator device
 *
 * Return: 0 if ok, non-zero if it fails.
 */
static int tps65090_fet_enable(struct regulator_dev *rdev)
{
        int ret, tries;

        /*
         * Try enabling multiple times until we succeed since sometimes the
         * first try times out.
         */
        tries = 0;
        while (true) {
                ret = tps65090_try_enable_fet(rdev);
                if (!ret)
                        break;
                if (ret != -ENOTRECOVERABLE || tries == MAX_FET_ENABLE_TRIES)
                        goto err;

                /* Try turning the FET off (and then on again) */
                ret = regmap_update_bits(rdev->regmap, rdev->desc->enable_reg,
                                         rdev->desc->enable_mask, 0);
                if (ret)
                        goto err;

                tries++;
        }

        if (tries)
                dev_warn(&rdev->dev, "reg %#x enable ok after %d tries\n",
                         rdev->desc->enable_reg, tries);

        return 0;
err:
        dev_warn(&rdev->dev, "reg %#x enable failed\n", rdev->desc->enable_reg);
        WARN_ON(1);

        return ret;
}

static struct regulator_ops tps65090_reg_control_ops = {
        .enable         = regulator_enable_regmap,
        .disable        = regulator_disable_regmap,
        .is_enabled     = regulator_is_enabled_regmap,
};

static struct regulator_ops tps65090_fet_control_ops = {
        .enable         = tps65090_fet_enable,
        .disable        = regulator_disable_regmap,
        .is_enabled     = regulator_is_enabled_regmap,
};

static struct regulator_ops tps65090_ldo_ops = {
};

#define tps65090_REG_DESC(_id, _sname, _en_reg, _en_bits, _nvolt, _volt, _ops) \
{                                                       \
        .name = "TPS65090_RAILS"#_id,                   \
        .supply_name = _sname,                          \
        .id = TPS65090_REGULATOR_##_id,                 \
        .n_voltages = _nvolt,                           \
        .ops = &_ops,                                   \
        .fixed_uV = _volt,                              \
        .enable_reg = _en_reg,                          \
        .enable_val = _en_bits,                         \
        .enable_mask = _en_bits,                        \
        .type = REGULATOR_VOLTAGE,                      \
        .owner = THIS_MODULE,                           \
}

#define tps65090_REG_FIXEDV(_id, _sname, en_reg, _en_bits, _volt, _ops) \
        tps65090_REG_DESC(_id, _sname, en_reg, _en_bits, 1, _volt, _ops)

#define tps65090_REG_SWITCH(_id, _sname, en_reg, _en_bits, _ops) \
        tps65090_REG_DESC(_id, _sname, en_reg, _en_bits, 0, 0, _ops)

static struct regulator_desc tps65090_regulator_desc[] = {
        tps65090_REG_FIXEDV(DCDC1, "vsys1",   0x0C, BIT(CTRL_EN_BIT), 5000000,
                            tps65090_reg_control_ops),
        tps65090_REG_FIXEDV(DCDC2, "vsys2",   0x0D, BIT(CTRL_EN_BIT), 3300000,
                            tps65090_reg_control_ops),
        tps65090_REG_SWITCH(DCDC3, "vsys3",   0x0E, BIT(CTRL_EN_BIT),
                            tps65090_reg_control_ops),

        tps65090_REG_SWITCH(FET1,  "infet1",  0x0F,
                            BIT(CTRL_EN_BIT) | BIT(CTRL_PG_BIT),
                            tps65090_fet_control_ops),
        tps65090_REG_SWITCH(FET2,  "infet2",  0x10,
                            BIT(CTRL_EN_BIT) | BIT(CTRL_PG_BIT),
                            tps65090_fet_control_ops),
        tps65090_REG_SWITCH(FET3,  "infet3",  0x11,
                            BIT(CTRL_EN_BIT) | BIT(CTRL_PG_BIT),
                            tps65090_fet_control_ops),
        tps65090_REG_SWITCH(FET4,  "infet4",  0x12,
                            BIT(CTRL_EN_BIT) | BIT(CTRL_PG_BIT),
                            tps65090_fet_control_ops),
        tps65090_REG_SWITCH(FET5,  "infet5",  0x13,
                            BIT(CTRL_EN_BIT) | BIT(CTRL_PG_BIT),
                            tps65090_fet_control_ops),
        tps65090_REG_SWITCH(FET6,  "infet6",  0x14,
                            BIT(CTRL_EN_BIT) | BIT(CTRL_PG_BIT),
                            tps65090_fet_control_ops),
        tps65090_REG_SWITCH(FET7,  "infet7",  0x15,
                            BIT(CTRL_EN_BIT) | BIT(CTRL_PG_BIT),
                            tps65090_fet_control_ops),

        tps65090_REG_FIXEDV(LDO1,  "vsys-l1", 0, 0, 5000000,
                            tps65090_ldo_ops),
        tps65090_REG_FIXEDV(LDO2,  "vsys-l2", 0, 0, 3300000,
                            tps65090_ldo_ops),
};

static inline bool is_dcdc(int id)
{
        switch (id) {
        case TPS65090_REGULATOR_DCDC1:
        case TPS65090_REGULATOR_DCDC2:
        case TPS65090_REGULATOR_DCDC3:
                return true;
        default:
                return false;
        }
}

static int tps65090_config_ext_control(
        struct tps65090_regulator *ri, bool enable)
{
        int ret;
        struct device *parent = ri->dev->parent;
        unsigned int reg_en_reg = ri->desc->enable_reg;

        if (enable)
                ret = tps65090_set_bits(parent, reg_en_reg, 1);
        else
                ret =  tps65090_clr_bits(parent, reg_en_reg, 1);
        if (ret < 0)
                dev_err(ri->dev, "Error in updating reg 0x%x\n", reg_en_reg);
        return ret;
}

static int tps65090_regulator_disable_ext_control(
                struct tps65090_regulator *ri,
                struct tps65090_regulator_plat_data *tps_pdata)
{
        int ret = 0;
        struct device *parent = ri->dev->parent;
        unsigned int reg_en_reg = ri->desc->enable_reg;

        /*
         * First enable output for internal control if require.
         * And then disable external control.
         */
        if (tps_pdata->reg_init_data->constraints.always_on ||
                        tps_pdata->reg_init_data->constraints.boot_on) {
                ret =  tps65090_set_bits(parent, reg_en_reg, 0);
                if (ret < 0) {
                        dev_err(ri->dev, "Error in set reg 0x%x\n", reg_en_reg);
                        return ret;
                }
        }
        return tps65090_config_ext_control(ri, false);
}

static void tps65090_configure_regulator_config(
                struct tps65090_regulator_plat_data *tps_pdata,
                struct regulator_config *config)
{
        if (gpio_is_valid(tps_pdata->gpio)) {
                int gpio_flag = GPIOF_OUT_INIT_LOW;

                if (tps_pdata->reg_init_data->constraints.always_on ||
                                tps_pdata->reg_init_data->constraints.boot_on)
                        gpio_flag = GPIOF_OUT_INIT_HIGH;

                config->ena_gpio = tps_pdata->gpio;
                config->ena_gpio_initialized = true;
                config->ena_gpio_flags = gpio_flag;
        } else {
                config->ena_gpio = -EINVAL;
                config->ena_gpio_initialized = false;
        }
}

#ifdef CONFIG_OF
static struct of_regulator_match tps65090_matches[] = {
        { .name = "dcdc1", },
        { .name = "dcdc2", },
        { .name = "dcdc3", },
        { .name = "fet1",  },
        { .name = "fet2",  },
        { .name = "fet3",  },
        { .name = "fet4",  },
        { .name = "fet5",  },
        { .name = "fet6",  },
        { .name = "fet7",  },
        { .name = "ldo1",  },
        { .name = "ldo2",  },
};

static struct tps65090_platform_data *tps65090_parse_dt_reg_data(
                struct platform_device *pdev,
                struct of_regulator_match **tps65090_reg_matches)
{
        struct tps65090_platform_data *tps65090_pdata;
        struct device_node *np = pdev->dev.parent->of_node;
        struct device_node *regulators;
        int idx = 0, ret;
        struct tps65090_regulator_plat_data *reg_pdata;

        tps65090_pdata = devm_kzalloc(&pdev->dev, sizeof(*tps65090_pdata),
                                GFP_KERNEL);
        if (!tps65090_pdata)
                return ERR_PTR(-ENOMEM);

        reg_pdata = devm_kzalloc(&pdev->dev, TPS65090_REGULATOR_MAX *
                                sizeof(*reg_pdata), GFP_KERNEL);
        if (!reg_pdata)
                return ERR_PTR(-ENOMEM);

        regulators = of_get_child_by_name(np, "regulators");
        if (!regulators) {
                dev_err(&pdev->dev, "regulator node not found\n");
                return ERR_PTR(-ENODEV);
        }

        ret = of_regulator_match(&pdev->dev, regulators, tps65090_matches,
                        ARRAY_SIZE(tps65090_matches));
        of_node_put(regulators);
        if (ret < 0) {
                dev_err(&pdev->dev,
                        "Error parsing regulator init data: %d\n", ret);
                return ERR_PTR(ret);
        }

        *tps65090_reg_matches = tps65090_matches;
        for (idx = 0; idx < ARRAY_SIZE(tps65090_matches); idx++) {
                struct regulator_init_data *ri_data;
                struct tps65090_regulator_plat_data *rpdata;

                rpdata = &reg_pdata[idx];
                ri_data = tps65090_matches[idx].init_data;
                if (!ri_data || !tps65090_matches[idx].of_node)
                        continue;

                rpdata->reg_init_data = ri_data;
                rpdata->enable_ext_control = of_property_read_bool(
                                        tps65090_matches[idx].of_node,
                                        "ti,enable-ext-control");
                if (rpdata->enable_ext_control)
                        rpdata->gpio = of_get_named_gpio(np,
                                        "dcdc-ext-control-gpios", 0);

                if (of_property_read_u32(tps65090_matches[idx].of_node,
                                         "ti,overcurrent-wait",
                                         &rpdata->overcurrent_wait) == 0)
                        rpdata->overcurrent_wait_valid = true;

                tps65090_pdata->reg_pdata[idx] = rpdata;
        }
        return tps65090_pdata;
}
#else
static inline struct tps65090_platform_data *tps65090_parse_dt_reg_data(
                        struct platform_device *pdev,
                        struct of_regulator_match **tps65090_reg_matches)
{
        *tps65090_reg_matches = NULL;
        return NULL;
}
#endif

static int tps65090_regulator_probe(struct platform_device *pdev)
{
        struct tps65090 *tps65090_mfd = dev_get_drvdata(pdev->dev.parent);
        struct tps65090_regulator *ri = NULL;
        struct regulator_config config = { };
        struct regulator_dev *rdev;
        struct tps65090_regulator_plat_data *tps_pdata;
        struct tps65090_regulator *pmic;
        struct tps65090_platform_data *tps65090_pdata;
        struct of_regulator_match *tps65090_reg_matches = NULL;
        int num;
        int ret;

        dev_dbg(&pdev->dev, "Probing regulator\n");

        tps65090_pdata = dev_get_platdata(pdev->dev.parent);
        if (!tps65090_pdata && tps65090_mfd->dev->of_node)
                tps65090_pdata = tps65090_parse_dt_reg_data(pdev,
                                        &tps65090_reg_matches);
        if (IS_ERR_OR_NULL(tps65090_pdata)) {
                dev_err(&pdev->dev, "Platform data missing\n");
                return tps65090_pdata ? PTR_ERR(tps65090_pdata) : -EINVAL;
        }

        pmic = devm_kzalloc(&pdev->dev, TPS65090_REGULATOR_MAX * sizeof(*pmic),
                        GFP_KERNEL);
        if (!pmic)
                return -ENOMEM;

        for (num = 0; num < TPS65090_REGULATOR_MAX; num++) {
                tps_pdata = tps65090_pdata->reg_pdata[num];

                ri = &pmic[num];
                ri->dev = &pdev->dev;
                ri->desc = &tps65090_regulator_desc[num];
                if (tps_pdata) {
                        ri->overcurrent_wait_valid =
                                tps_pdata->overcurrent_wait_valid;
                        ri->overcurrent_wait = tps_pdata->overcurrent_wait;
                }

                /*
                 * TPS5090 DCDC support the control from external digital input.
                 * Configure it as per platform data.
                 */
                if (tps_pdata && is_dcdc(num) && tps_pdata->reg_init_data) {
                        if (tps_pdata->enable_ext_control) {
                                tps65090_configure_regulator_config(
                                                tps_pdata, &config);
                                ri->desc->ops = &tps65090_ext_control_ops;
                        } else {
                                ret = tps65090_regulator_disable_ext_control(
                                                ri, tps_pdata);
                                if (ret < 0) {
                                        dev_err(&pdev->dev,
                                                "failed disable ext control\n");
                                        return ret;
                                }
                        }
                }

                config.dev = pdev->dev.parent;
                config.driver_data = ri;
                config.regmap = tps65090_mfd->rmap;
                if (tps_pdata)
                        config.init_data = tps_pdata->reg_init_data;
                else
                        config.init_data = NULL;
                if (tps65090_reg_matches)
                        config.of_node = tps65090_reg_matches[num].of_node;
                else
                        config.of_node = NULL;

                rdev = devm_regulator_register(&pdev->dev, ri->desc, &config);
                if (IS_ERR(rdev)) {
                        dev_err(&pdev->dev, "failed to register regulator %s\n",
                                ri->desc->name);
                        return PTR_ERR(rdev);
                }
                ri->rdev = rdev;

                if (ri->overcurrent_wait_valid) {
                        ret = tps65090_reg_set_overcurrent_wait(ri, rdev);
                        if (ret < 0)
                                return ret;
                }

                /* Enable external control if it is require */
                if (tps_pdata && is_dcdc(num) && tps_pdata->reg_init_data &&
                                tps_pdata->enable_ext_control) {
                        ret = tps65090_config_ext_control(ri, true);
                        if (ret < 0)
                                return ret;
                }
        }

        platform_set_drvdata(pdev, pmic);
        return 0;
}

static struct platform_driver tps65090_regulator_driver = {
        .driver = {
                .name   = "tps65090-pmic",
        },
        .probe          = tps65090_regulator_probe,
};

static int __init tps65090_regulator_init(void)
{
        return platform_driver_register(&tps65090_regulator_driver);
}
subsys_initcall(tps65090_regulator_init);

static void __exit tps65090_regulator_exit(void)
{
        platform_driver_unregister(&tps65090_regulator_driver);
}
module_exit(tps65090_regulator_exit);

MODULE_DESCRIPTION("tps65090 regulator driver");
MODULE_AUTHOR("Venu Byravarasu <vbyravarasu@nvidia.com>");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:tps65090-pmic");