// SPDX-License-Identifier: GPL-2.0
//
// Copyright (c) 2024 MediaTek Inc.
// Copyright (c) 2025 Collabora Ltd
//                    AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

#include <linux/module.h>
#include <linux/of.h>
#include <linux/regmap.h>
#include <linux/spmi.h>

#include <linux/regulator/driver.h>
#include <linux/regulator/machine.h>
#include <linux/regulator/of_regulator.h>

#define MT6316_BUCK_MODE_AUTO                   0
#define MT6316_BUCK_MODE_FORCE_PWM              1
#define MT6316_BUCK_MODE_LP                     2

#define MT6316_CHIP_ID                          0x20b
#define MT6316_BUCK_TOP_CON0                    0x1440
#define EN_SET_OFFSET                           0x1
#define EN_CLR_OFFSET                           0x2

#define MT6316_BUCK_TOP_CON1                    0x1443

#define MT6316_BUCK_TOP_ELR0                    0x1448
#define MT6316_BUCK_TOP_ELR2                    0x144a
#define MT6316_BUCK_TOP_ELR4                    0x144c
#define MT6316_BUCK_TOP_ELR6                    0x144e
#define MT6316_VSEL_MASK                        GENMASK(8, 0)

#define MT6316_VBUCK1_DBG                       0x14a8
#define MT6316_VBUCK2_DBG                       0x1528
#define MT6316_VBUCK3_DBG                       0x15a8
#define MT6316_VBUCK4_DBG                       0x1628
#define MT6316_BUCK_QI                          BIT(0)

#define MT6316_BUCK_TOP_4PHASE_TOP_ANA_CON0     0x1688
#define MT6316_BUCK_TOP_4PHASE_TOP_ELR_0        0x1690

enum mt6316_type {
        MT6316_TYPE_2PHASE,
        MT6316_TYPE_3PHASE,
        MT6316_TYPE_4PHASE
};

/**
 * struct mt6316_regulator_info - MT6316 regulators information
 * @desc: Regulator description structure
 * @debug_reg: Debug register for regulator status
 * @lp_mode_reg: Low Power mode register (normal/idle)
 * @lp_mode_mask: Low Power mode regulator mask
 * @modeset_reg: AUTO/PWM mode register
 * @modeset_mask: AUTO/PWM regulator mask
 */
struct mt6316_regulator_info {
        struct regulator_desc desc;
        u16 debug_reg;
        u16 lp_mode_reg;
        u16 lp_mode_mask;
        u16 modeset_reg;
        u16 modeset_mask;
};

#define MT6316_BUCK(match, vreg_id, min, max, step, vs_reg)             \
{                                                                       \
        .desc = {                                                       \
                .name = match,                                          \
                .of_match = of_match_ptr(match),                        \
                .ops = &mt6316_vreg_setclr_ops,                         \
                .type = REGULATOR_VOLTAGE,                              \
                .owner = THIS_MODULE,                                   \
                .n_voltages = (max - min) / step + 1,                   \
                .min_uV = min,                                          \
                .uV_step = step,                                        \
                .enable_reg = MT6316_BUCK_TOP_CON0,                     \
                .enable_mask = BIT(vreg_id - 1),                        \
                .vsel_reg = vs_reg,                                     \
                .vsel_mask = MT6316_VSEL_MASK,                          \
                .of_map_mode = mt6316_map_mode,                         \
        },                                                              \
        .lp_mode_reg = MT6316_BUCK_TOP_CON1,                            \
        .lp_mode_mask = BIT(vreg_id - 1),                               \
        .modeset_reg = MT6316_BUCK_TOP_4PHASE_TOP_ANA_CON0,             \
        .modeset_mask = BIT(vreg_id - 1),                               \
        .debug_reg = MT6316_VBUCK##vreg_id##_DBG,                       \
}

/* Values in some MT6316 registers are big endian, 9 bits long... */
static inline u16 mt6316_be9_to_cpu(u16 val)
{
        return ((val >> 8) & BIT(0)) | ((val & GENMASK(7, 0)) << 1);
}

static inline u16 mt6316_cpu_to_be9(u16 val)
{
        return ((val & BIT(0)) << 8) | (val >> 1);
}

static unsigned int mt6316_map_mode(u32 mode)
{
        switch (mode) {
        case MT6316_BUCK_MODE_AUTO:
                return REGULATOR_MODE_NORMAL;
        case MT6316_BUCK_MODE_FORCE_PWM:
                return REGULATOR_MODE_FAST;
        case MT6316_BUCK_MODE_LP:
                return REGULATOR_MODE_IDLE;
        default:
                return REGULATOR_MODE_INVALID;
        }
}

static int mt6316_vreg_enable_setclr(struct regulator_dev *rdev)
{
        return regmap_write(rdev->regmap, rdev->desc->enable_reg + EN_SET_OFFSET,
                            rdev->desc->enable_mask);
}

static int mt6316_vreg_disable_setclr(struct regulator_dev *rdev)
{
        return regmap_write(rdev->regmap, rdev->desc->enable_reg + EN_CLR_OFFSET,
                            rdev->desc->enable_mask);
}

static int mt6316_regulator_set_voltage_sel(struct regulator_dev *rdev, unsigned int selector)
{
        u16 val = mt6316_cpu_to_be9(selector);

        return regmap_bulk_write(rdev->regmap, rdev->desc->vsel_reg, &val, sizeof(val));
}

static int mt6316_regulator_get_voltage_sel(struct regulator_dev *rdev)
{
        u16 val;
        int ret;

        ret = regmap_bulk_read(rdev->regmap, rdev->desc->vsel_reg, &val, sizeof(val));
        if (ret)
                return ret;

        return mt6316_be9_to_cpu(val & rdev->desc->vsel_mask);
}

static int mt6316_regulator_get_status(struct regulator_dev *rdev)
{
        struct mt6316_regulator_info *info = rdev_get_drvdata(rdev);
        u32 val;
        int ret;

        ret = regmap_read(rdev->regmap, info->debug_reg, &val);
        if (ret)
                return ret;

        return val & MT6316_BUCK_QI ? REGULATOR_STATUS_ON : REGULATOR_STATUS_OFF;
}

static unsigned int mt6316_regulator_get_mode(struct regulator_dev *rdev)
{
        struct mt6316_regulator_info *info = rdev_get_drvdata(rdev);
        unsigned int val;
        int ret;

        ret = regmap_read(rdev->regmap, info->modeset_reg, &val);
        if (ret) {
                dev_err(&rdev->dev, "Failed to get mode: %d\n", ret);
                return ret;
        }

        if ((val & info->modeset_mask) == info->modeset_mask)
                return REGULATOR_MODE_FAST;

        ret = regmap_read(rdev->regmap, info->lp_mode_reg, &val);
        val &= info->lp_mode_mask;
        if (ret) {
                dev_err(&rdev->dev, "Failed to get lp mode: %d\n", ret);
                return ret;
        }

        return val ? REGULATOR_MODE_IDLE : REGULATOR_MODE_NORMAL;
}

static int mt6316_regulator_set_mode(struct regulator_dev *rdev,
                                     unsigned int mode)
{
        struct mt6316_regulator_info *info = rdev_get_drvdata(rdev);
        struct regmap *regmap = rdev->regmap;
        int cur_mode, ret;

        switch (mode) {
        case REGULATOR_MODE_FAST:
                ret = regmap_set_bits(regmap, info->modeset_reg, info->modeset_mask);
                break;
        case REGULATOR_MODE_NORMAL:
                cur_mode = mt6316_regulator_get_mode(rdev);
                if (cur_mode < 0) {
                        ret = cur_mode;
                        break;
                }

                if (cur_mode == REGULATOR_MODE_FAST) {
                        ret = regmap_clear_bits(regmap, info->modeset_reg, info->modeset_mask);
                        break;
                } else if (cur_mode == REGULATOR_MODE_IDLE) {
                        ret = regmap_clear_bits(regmap, info->lp_mode_reg, info->lp_mode_mask);
                        if (ret == 0)
                                usleep_range(100, 200);
                } else {
                        ret = 0;
                }
                break;
        case REGULATOR_MODE_IDLE:
                ret = regmap_set_bits(regmap, info->lp_mode_reg, info->lp_mode_mask);
                break;
        default:
                ret = -EINVAL;
        }

        if (ret) {
                dev_err(&rdev->dev, "Failed to set mode %u: %d\n", mode, ret);
                return ret;
        }

        return 0;
}

static const struct regulator_ops mt6316_vreg_setclr_ops = {
        .list_voltage = regulator_list_voltage_linear,
        .map_voltage = regulator_map_voltage_linear,
        .set_voltage_sel = mt6316_regulator_set_voltage_sel,
        .get_voltage_sel = mt6316_regulator_get_voltage_sel,
        .set_voltage_time_sel = regulator_set_voltage_time_sel,
        .enable = mt6316_vreg_enable_setclr,
        .disable = mt6316_vreg_disable_setclr,
        .is_enabled = regulator_is_enabled_regmap,
        .get_status = mt6316_regulator_get_status,
        .set_mode = mt6316_regulator_set_mode,
        .get_mode = mt6316_regulator_get_mode,
};

/* MT6316BP/VP - 2+2 phase buck */
static struct mt6316_regulator_info mt6316bv_regulators[] = {
        MT6316_BUCK("vbuck12", 1, 0, 1277500, 2500, MT6316_BUCK_TOP_ELR0),
        MT6316_BUCK("vbuck34", 3, 0, 1277500, 2500, MT6316_BUCK_TOP_ELR4),
};

/* MT6316CP/HP/KP - 3+1 phase buck */
static struct mt6316_regulator_info mt6316chk_regulators[] = {
        MT6316_BUCK("vbuck124", 1, 0, 1277500, 2500, MT6316_BUCK_TOP_ELR0),
        MT6316_BUCK("vbuck3", 3, 0, 1277500, 2500, MT6316_BUCK_TOP_ELR4),
};

/* MT6316DP/TP - 4 phase buck */
static struct mt6316_regulator_info mt6316dt_regulators[] = {
        MT6316_BUCK("vbuck1234", 1, 0, 1277500, 2500, MT6316_BUCK_TOP_ELR0),
};

static const struct regmap_config mt6316_spmi_regmap_config = {
        .reg_bits       = 16,
        .val_bits       = 8,
        .max_register   = 0x1700,
        .fast_io        = true,
};

static int mt6316_regulator_probe(struct spmi_device *sdev)
{
        struct regulator_config config = {};
        struct mt6316_regulator_info *info;
        struct regulator_dev *rdev;
        enum mt6316_type type;
        int num_vregs, ret;
        unsigned int i;
        u32 chip_id;

        config.regmap = devm_regmap_init_spmi_ext(sdev, &mt6316_spmi_regmap_config);
        if (IS_ERR(config.regmap))
                return PTR_ERR(config.regmap);

        /*
         * The first read is expected to fail: this PMIC needs to be woken up
         * and that can be done with any activity over the SPMI bus.
         */
        regmap_read(config.regmap, MT6316_CHIP_ID, &chip_id);

        /* The second read, instead, shall not fail! */
        ret = regmap_read(config.regmap, MT6316_CHIP_ID, &chip_id);
        if (ret) {
                dev_err(&sdev->dev, "Cannot read Chip ID!\n");
                return ret;
        }
        dev_dbg(&sdev->dev, "Chip ID: 0x%x\n", chip_id);

        config.dev = &sdev->dev;

        type = (uintptr_t)device_get_match_data(&sdev->dev);
        switch (type) {
        case MT6316_TYPE_2PHASE:
                info = mt6316bv_regulators;
                num_vregs = ARRAY_SIZE(mt6316bv_regulators);
                break;
        case MT6316_TYPE_3PHASE:
                info = mt6316chk_regulators;
                num_vregs = ARRAY_SIZE(mt6316chk_regulators);
                break;
        case MT6316_TYPE_4PHASE:
                info = mt6316dt_regulators;
                num_vregs = ARRAY_SIZE(mt6316dt_regulators);
                break;
        default:
                return -EINVAL;
        }

        for (i = 0; i < num_vregs; i++) {
                config.driver_data = &info[i];

                rdev = devm_regulator_register(&sdev->dev, &info[i].desc, &config);
                if (IS_ERR(rdev))
                        return dev_err_probe(&sdev->dev, PTR_ERR(rdev),
                                             "failed to register %s\n", info[i].desc.name);
        }

        return 0;
}

static const struct of_device_id mt6316_regulator_match[] = {
        { .compatible = "mediatek,mt6316b-regulator", .data = (void *)MT6316_TYPE_2PHASE },
        { .compatible = "mediatek,mt6316c-regulator", .data = (void *)MT6316_TYPE_3PHASE },
        { .compatible = "mediatek,mt6316d-regulator", .data = (void *)MT6316_TYPE_4PHASE },
        { /* sentinel */ }
};

static struct spmi_driver mt6316_regulator_driver = {
        .driver = {
                .name = "mt6316-regulator",
                .probe_type = PROBE_PREFER_ASYNCHRONOUS,
                .of_match_table = mt6316_regulator_match,
        },
        .probe = mt6316_regulator_probe,
};
module_spmi_driver(mt6316_regulator_driver);

MODULE_AUTHOR("AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>");
MODULE_DESCRIPTION("Regulator Driver for MediaTek MT6316 PMIC");
MODULE_LICENSE("GPL");