// SPDX-License-Identifier: GPL-2.0-only
/*
 * LED driver for STMicroelectronics LED1202 chip
 *
 * Copyright (C) 2024 Remote-Tech Ltd. UK
 */

#include <linux/cleanup.h>
#include <linux/ctype.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/gpio.h>
#include <linux/i2c.h>
#include <linux/leds.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/string.h>

#define ST1202_CHAN_DISABLE_ALL            0x00
#define ST1202_CHAN_ENABLE_HIGH            0x03
#define ST1202_CHAN_ENABLE_LOW             0x02
#define ST1202_CONFIG_REG                  0x04
/* PATS: Pattern sequence feature enable */
#define ST1202_CONFIG_REG_PATS             BIT(7)
/* PATSR: Pattern sequence runs (self-clear when sequence is finished) */
#define ST1202_CONFIG_REG_PATSR            BIT(6)
#define ST1202_CONFIG_REG_SHFT             BIT(3)
#define ST1202_DEV_ENABLE                  0x01
#define ST1202_DEV_ENABLE_ON               BIT(0)
#define ST1202_DEV_ENABLE_RESET            BIT(7)
#define ST1202_DEVICE_ID                   0x00
#define ST1202_ILED_REG0                   0x09
#define ST1202_MAX_LEDS                    12
#define ST1202_MAX_PATTERNS                8
#define ST1202_MILLIS_PATTERN_DUR_MAX      5660
#define ST1202_MILLIS_PATTERN_DUR_MIN      22
#define ST1202_PATTERN_DUR                 0x16
#define ST1202_PATTERN_PWM                 0x1E
#define ST1202_PATTERN_REP                 0x15

struct st1202_led {
        struct fwnode_handle *fwnode;
        struct led_classdev led_cdev;
        struct st1202_chip *chip;
        bool is_active;
        int led_num;
};

struct st1202_chip {
        struct i2c_client *client;
        struct mutex lock;
        struct st1202_led leds[ST1202_MAX_LEDS];
};

static struct st1202_led *cdev_to_st1202_led(struct led_classdev *cdev)
{
        return container_of(cdev, struct st1202_led, led_cdev);
}

static int st1202_read_reg(struct st1202_chip *chip, int reg, uint8_t *val)
{
        struct device *dev = &chip->client->dev;
        int ret;

        ret = i2c_smbus_read_byte_data(chip->client, reg);
        if (ret < 0) {
                dev_err(dev, "Failed to read register [0x%x]: %d\n", reg, ret);
                return ret;
        }

        *val = (uint8_t)ret;
        return 0;
}

static int st1202_write_reg(struct st1202_chip *chip, int reg, uint8_t val)
{
        struct device *dev = &chip->client->dev;
        int ret;

        ret = i2c_smbus_write_byte_data(chip->client, reg, val);
        if (ret != 0)
                dev_err(dev, "Failed to write %d to register [0x%x]: %d\n", val, reg, ret);

        return ret;
}

static uint8_t st1202_prescalar_to_miliseconds(unsigned int value)
{
        return value / ST1202_MILLIS_PATTERN_DUR_MIN - 1;
}

static int st1202_pwm_pattern_write(struct st1202_chip *chip, int led_num,
                                int pattern, unsigned int value)
{
        u8 value_l, value_h;
        int ret;

        value_l = (u8)value;
        value_h = (u8)(value >> 8);

        /*
         * Datasheet: Register address low = 1Eh + 2*(xh) + 18h*(yh),
         * where x is the channel number (led number) in hexadecimal (x = 00h .. 0Bh)
         * and y is the pattern number in hexadecimal (y = 00h .. 07h)
         */
        ret = st1202_write_reg(chip, (ST1202_PATTERN_PWM + (led_num * 2) + 0x18 * pattern),
                                value_l);
        if (ret != 0)
                return ret;

        /*
         * Datasheet: Register address high = 1Eh + 01h + 2(xh) +18h*(yh),
         * where x is the channel number in hexadecimal (x = 00h .. 0Bh)
         * and y is the pattern number in hexadecimal (y = 00h .. 07h)
         */
        ret = st1202_write_reg(chip, (ST1202_PATTERN_PWM + 0x1 + (led_num * 2) + 0x18 * pattern),
                                value_h);
        if (ret != 0)
                return ret;

        return 0;
}

static int st1202_duration_pattern_write(struct st1202_chip *chip, int pattern,
                                        unsigned int value)
{
        return st1202_write_reg(chip, (ST1202_PATTERN_DUR + pattern),
                                st1202_prescalar_to_miliseconds(value));
}

static void st1202_brightness_set(struct led_classdev *led_cdev,
                                enum led_brightness value)
{
        struct st1202_led *led = cdev_to_st1202_led(led_cdev);
        struct st1202_chip *chip = led->chip;

        guard(mutex)(&chip->lock);

        st1202_write_reg(chip, ST1202_ILED_REG0 + led->led_num, value);
}

static enum led_brightness st1202_brightness_get(struct led_classdev *led_cdev)
{
        struct st1202_led *led = cdev_to_st1202_led(led_cdev);
        struct st1202_chip *chip = led->chip;
        u8 value = 0;

        guard(mutex)(&chip->lock);

        st1202_read_reg(chip, ST1202_ILED_REG0 + led->led_num, &value);

        return value;
}

static int st1202_channel_set(struct st1202_chip *chip, int led_num, bool active)
{
        u8 chan_low, chan_high;
        int ret;

        guard(mutex)(&chip->lock);

        if (led_num <= 7) {
                ret = st1202_read_reg(chip, ST1202_CHAN_ENABLE_LOW, &chan_low);
                if (ret < 0)
                        return ret;

                chan_low = active ? chan_low | BIT(led_num) : chan_low & ~BIT(led_num);

                ret = st1202_write_reg(chip, ST1202_CHAN_ENABLE_LOW, chan_low);
                if (ret < 0)
                        return ret;

        } else {
                ret = st1202_read_reg(chip, ST1202_CHAN_ENABLE_HIGH, &chan_high);
                if (ret < 0)
                        return ret;

                chan_high = active ? chan_high | (BIT(led_num) >> 8) :
                                        chan_high & ~(BIT(led_num) >> 8);

                ret = st1202_write_reg(chip, ST1202_CHAN_ENABLE_HIGH, chan_high);
                if (ret < 0)
                        return ret;
        }

        return 0;
}

static int st1202_led_set(struct led_classdev *ldev, enum led_brightness value)
{
        struct st1202_led *led = cdev_to_st1202_led(ldev);

        return st1202_channel_set(led->chip, led->led_num, !!value);
}

static int st1202_led_pattern_clear(struct led_classdev *ldev)
{
        struct st1202_led *led = cdev_to_st1202_led(ldev);
        struct st1202_chip *chip = led->chip;
        int ret;

        guard(mutex)(&chip->lock);

        for (int patt = 0; patt < ST1202_MAX_PATTERNS; patt++) {
                ret = st1202_pwm_pattern_write(chip, led->led_num, patt, LED_OFF);
                if (ret != 0)
                        return ret;

                ret = st1202_duration_pattern_write(chip, patt, ST1202_MILLIS_PATTERN_DUR_MIN);
                if (ret != 0)
                        return ret;
        }

        return 0;
}

static int st1202_led_pattern_set(struct led_classdev *ldev,
                                struct led_pattern *pattern,
                                u32 len, int repeat)
{
        struct st1202_led *led = cdev_to_st1202_led(ldev);
        struct st1202_chip *chip = led->chip;
        int ret;

        if (len > ST1202_MAX_PATTERNS)
                return -EINVAL;

        guard(mutex)(&chip->lock);

        for (int patt = 0; patt < len; patt++) {
                if (pattern[patt].delta_t < ST1202_MILLIS_PATTERN_DUR_MIN ||
                                pattern[patt].delta_t > ST1202_MILLIS_PATTERN_DUR_MAX)
                        return -EINVAL;

                ret = st1202_pwm_pattern_write(chip, led->led_num, patt, pattern[patt].brightness);
                if (ret != 0)
                        return ret;

                ret = st1202_duration_pattern_write(chip, patt, pattern[patt].delta_t);
                if (ret != 0)
                        return ret;
        }

        ret = st1202_write_reg(chip, ST1202_PATTERN_REP, repeat);
        if (ret != 0)
                return ret;

        ret = st1202_write_reg(chip, ST1202_CONFIG_REG, (ST1202_CONFIG_REG_PATSR |
                                                        ST1202_CONFIG_REG_PATS | ST1202_CONFIG_REG_SHFT));
        if (ret != 0)
                return ret;

        return 0;
}

static int st1202_dt_init(struct st1202_chip *chip)
{
        struct device *dev = &chip->client->dev;
        struct st1202_led *led;
        int err, reg;

        for_each_available_child_of_node_scoped(dev_of_node(dev), child) {
                err = of_property_read_u32(child, "reg", &reg);
                if (err)
                        return dev_err_probe(dev, err, "Invalid register\n");

                led = &chip->leds[reg];
                led->is_active = true;
                led->fwnode = of_fwnode_handle(child);

                led->led_cdev.max_brightness = U8_MAX;
                led->led_cdev.brightness_set_blocking = st1202_led_set;
                led->led_cdev.pattern_set = st1202_led_pattern_set;
                led->led_cdev.pattern_clear = st1202_led_pattern_clear;
                led->led_cdev.default_trigger = "pattern";
                led->led_cdev.brightness_set = st1202_brightness_set;
                led->led_cdev.brightness_get = st1202_brightness_get;
        }

        return 0;
}

static int st1202_setup(struct st1202_chip *chip)
{
        int ret;

        guard(mutex)(&chip->lock);

        /*
         * Once the supply voltage is applied, the LED1202 executes some internal checks.
         * Afterwards, it stops the oscillator and puts the internal LDO in quiescent mode.
         * To start the device, EN bit must be set inside the “Device Enable” register at
         * address 01h. As soon as EN is set, the LED1202 loads the adjustment parameters
         * from the internal non-volatile memory and performs an auto-calibration procedure
         * in order to increase the output current precision.
         * Such initialization lasts about 6.5 ms.
         */

        /* Reset the chip during setup */
        ret = st1202_write_reg(chip, ST1202_DEV_ENABLE, ST1202_DEV_ENABLE_RESET);
        if (ret < 0)
                return ret;

        /* Enable phase-shift delay feature */
        ret = st1202_write_reg(chip, ST1202_CONFIG_REG, ST1202_CONFIG_REG_SHFT);
        if (ret < 0)
                return ret;

        /* Enable the device */
        ret = st1202_write_reg(chip, ST1202_DEV_ENABLE, ST1202_DEV_ENABLE_ON);
        if (ret < 0)
                return ret;

        /* Duration of initialization */
        usleep_range(6500, 10000);

        /* Deactivate all LEDS (channels) and activate only the ones found in Device Tree */
        ret = st1202_write_reg(chip, ST1202_CHAN_ENABLE_LOW, ST1202_CHAN_DISABLE_ALL);
        if (ret < 0)
                return ret;

        ret = st1202_write_reg(chip, ST1202_CHAN_ENABLE_HIGH, ST1202_CHAN_DISABLE_ALL);
        if (ret < 0)
                return ret;

        ret = st1202_write_reg(chip, ST1202_CONFIG_REG,
                                ST1202_CONFIG_REG_PATS | ST1202_CONFIG_REG_PATSR);
        if (ret < 0)
                return ret;

        return 0;
}

static int st1202_probe(struct i2c_client *client)
{
        struct st1202_chip *chip;
        struct st1202_led *led;
        int ret;

        if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
                return dev_err_probe(&client->dev, -EIO, "SMBUS Byte Data not Supported\n");

        chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
        if (!chip)
                return -ENOMEM;

        ret = devm_mutex_init(&client->dev, &chip->lock);
        if (ret < 0)
                return ret;
        chip->client = client;

        ret = st1202_setup(chip);
        if (ret < 0)
                return ret;

        ret = st1202_dt_init(chip);
        if (ret < 0)
                return ret;

        for (int i = 0; i < ST1202_MAX_LEDS; i++) {
                struct led_init_data init_data = {};
                led = &chip->leds[i];
                led->chip = chip;
                led->led_num = i;

                if (!led->is_active)
                        continue;

                ret = st1202_channel_set(led->chip, led->led_num, true);
                if (ret < 0)
                        return dev_err_probe(&client->dev, ret,
                                        "Failed to activate LED channel\n");

                ret = st1202_led_pattern_clear(&led->led_cdev);
                if (ret < 0)
                        return dev_err_probe(&client->dev, ret,
                                        "Failed to clear LED pattern\n");

                init_data.fwnode = led->fwnode;
                init_data.devicename = "st1202";
                init_data.default_label = ":";

                ret = devm_led_classdev_register_ext(&client->dev, &led->led_cdev, &init_data);
                if (ret < 0)
                        return dev_err_probe(&client->dev, ret,
                                        "Failed to register LED class device\n");
        }

        return 0;
}

static const struct i2c_device_id st1202_id[] = {
        { "st1202-i2c" },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(i2c, st1202_id);

static const struct of_device_id st1202_dt_ids[] = {
        { .compatible = "st,led1202" },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, st1202_dt_ids);

static struct i2c_driver st1202_driver = {
        .driver = {
                .name = "leds-st1202",
                .of_match_table = of_match_ptr(st1202_dt_ids),
        },
        .probe = st1202_probe,
        .id_table = st1202_id,
};
module_i2c_driver(st1202_driver);

MODULE_AUTHOR("Remote Tech LTD");
MODULE_DESCRIPTION("STMicroelectronics LED1202 : 12-channel constant current LED driver");
MODULE_LICENSE("GPL");