// SPDX-License-Identifier: GPL-2.0-or-later
//
// max20086-regulator.c - MAX20086-MAX20089 camera power protector driver
//
// Copyright (C) 2022 Laurent Pinchart <laurent.pinchart@idesonboard.com>
// Copyright (C) 2018 Avnet, Inc.

#include <linux/err.h>
#include <linux/gpio.h>
#include <linux/gpio/consumer.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/regmap.h>
#include <linux/regulator/driver.h>
#include <linux/regulator/machine.h>
#include <linux/regulator/of_regulator.h>
#include <linux/slab.h>

/* Register Offset */
#define MAX20086_REG_MASK		0x00
#define MAX20086_REG_CONFIG		0x01
#define	MAX20086_REG_ID			0x02
#define	MAX20086_REG_STAT1		0x03
#define	MAX20086_REG_STAT2_L		0x04
#define	MAX20086_REG_STAT2_H		0x05
#define	MAX20086_REG_ADC1		0x06
#define	MAX20086_REG_ADC2		0x07
#define	MAX20086_REG_ADC3		0x08
#define	MAX20086_REG_ADC4		0x09

/* DEVICE IDs */
#define MAX20086_DEVICE_ID_MAX20086	0x40
#define MAX20086_DEVICE_ID_MAX20087	0x20
#define MAX20086_DEVICE_ID_MAX20088	0x10
#define MAX20086_DEVICE_ID_MAX20089	0x00
#define DEVICE_ID_MASK			0xf0

/* Register bits */
#define MAX20086_EN_MASK		0x0f
#define MAX20086_EN_OUT1		0x01
#define MAX20086_EN_OUT2		0x02
#define MAX20086_EN_OUT3		0x04
#define MAX20086_EN_OUT4		0x08
#define MAX20086_INT_DISABLE_ALL	0x3f

#define MAX20086_MAX_REGULATORS		4

struct max20086_chip_info {
	u8 id;
	unsigned int num_outputs;
};

struct max20086_regulator {
	struct device_node *of_node;
	struct regulator_init_data *init_data;
	const struct regulator_desc *desc;
	struct regulator_dev *rdev;
};

struct max20086 {
	struct device *dev;
	struct regmap *regmap;
	struct gpio_desc *ena_gpiod;

	const struct max20086_chip_info *info;

	struct max20086_regulator regulators[MAX20086_MAX_REGULATORS];
};

static const struct regulator_ops max20086_buck_ops = {
	.enable = regulator_enable_regmap,
	.disable = regulator_disable_regmap,
	.is_enabled = regulator_is_enabled_regmap,
};

#define MAX20086_REGULATOR_DESC(n)		\
{						\
	.name = "OUT"#n,			\
	.supply_name = "in",			\
	.id = (n) - 1,				\
	.ops = &max20086_buck_ops,		\
	.type = REGULATOR_VOLTAGE,		\
	.owner = THIS_MODULE,			\
	.enable_reg = MAX20086_REG_CONFIG,	\
	.enable_mask = 1 << ((n) - 1),		\
	.enable_val = 1 << ((n) - 1),		\
	.disable_val = 0,			\
}

static const char * const max20086_output_names[] = {
	"OUT1",
	"OUT2",
	"OUT3",
	"OUT4",
};

static const struct regulator_desc max20086_regulators[] = {
	MAX20086_REGULATOR_DESC(1),
	MAX20086_REGULATOR_DESC(2),
	MAX20086_REGULATOR_DESC(3),
	MAX20086_REGULATOR_DESC(4),
};

static int max20086_regulators_register(struct max20086 *chip)
{
	unsigned int i;

	for (i = 0; i < chip->info->num_outputs; i++) {
		struct max20086_regulator *reg = &chip->regulators[i];
		struct regulator_config config = { };
		struct regulator_dev *rdev;

		config.dev = chip->dev;
		config.init_data = reg->init_data;
		config.driver_data = chip;
		config.of_node = reg->of_node;
		config.regmap = chip->regmap;
		config.ena_gpiod = chip->ena_gpiod;

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

		reg->rdev = rdev;
	}

	return 0;
}

static int max20086_parse_regulators_dt(struct max20086 *chip, bool *boot_on)
{
	struct of_regulator_match matches[MAX20086_MAX_REGULATORS] = { };
	struct device_node *node;
	unsigned int i;
	int ret;

	node = of_get_child_by_name(chip->dev->of_node, "regulators");
	if (!node) {
		dev_err(chip->dev, "regulators node not found\n");
		return -ENODEV;
	}

	for (i = 0; i < chip->info->num_outputs; ++i)
		matches[i].name = max20086_output_names[i];

	ret = of_regulator_match(chip->dev, node, matches,
				 chip->info->num_outputs);
	of_node_put(node);
	if (ret < 0) {
		dev_err(chip->dev, "Failed to match regulators\n");
		return -EINVAL;
	}

	*boot_on = false;

	for (i = 0; i < chip->info->num_outputs; i++) {
		struct max20086_regulator *reg = &chip->regulators[i];

		reg->init_data = matches[i].init_data;
		reg->of_node = matches[i].of_node;
		reg->desc = &max20086_regulators[i];

		if (reg->init_data) {
			if (reg->init_data->constraints.always_on ||
			    reg->init_data->constraints.boot_on)
				*boot_on = true;
		}
	}

	return 0;
}

static int max20086_detect(struct max20086 *chip)
{
	unsigned int data;
	int ret;

	ret = regmap_read(chip->regmap, MAX20086_REG_ID, &data);
	if (ret < 0) {
		dev_err(chip->dev, "Failed to read DEVICE_ID reg: %d\n", ret);
		return ret;
	}

	if ((data & DEVICE_ID_MASK) != chip->info->id) {
		dev_err(chip->dev, "Invalid device ID 0x%02x\n", data);
		return -ENXIO;
	}

	return 0;
}

static bool max20086_gen_is_writeable_reg(struct device *dev, unsigned int reg)
{
	switch (reg) {
	case MAX20086_REG_MASK:
	case MAX20086_REG_CONFIG:
		return true;
	default:
		return false;
	}
}

static const struct regmap_config max20086_regmap_config = {
	.reg_bits = 8,
	.val_bits = 8,
	.writeable_reg = max20086_gen_is_writeable_reg,
	.max_register = 0x9,
	.cache_type = REGCACHE_NONE,
};

static int max20086_i2c_probe(struct i2c_client *i2c)
{
	struct max20086 *chip;
	enum gpiod_flags flags;
	bool boot_on;
	int ret;

	chip = devm_kzalloc(&i2c->dev, sizeof(*chip), GFP_KERNEL);
	if (!chip)
		return -ENOMEM;

	chip->dev = &i2c->dev;
	chip->info = device_get_match_data(chip->dev);

	i2c_set_clientdata(i2c, chip);

	chip->regmap = devm_regmap_init_i2c(i2c, &max20086_regmap_config);
	if (IS_ERR(chip->regmap)) {
		ret = PTR_ERR(chip->regmap);
		dev_err(chip->dev, "Failed to allocate register map: %d\n", ret);
		return ret;
	}

	ret = max20086_parse_regulators_dt(chip, &boot_on);
	if (ret < 0)
		return ret;

	ret = max20086_detect(chip);
	if (ret < 0)
		return ret;

	/* Until IRQ support is added, just disable all interrupts. */
	ret = regmap_update_bits(chip->regmap, MAX20086_REG_MASK,
				 MAX20086_INT_DISABLE_ALL,
				 MAX20086_INT_DISABLE_ALL);
	if (ret < 0) {
		dev_err(chip->dev, "Failed to disable interrupts: %d\n", ret);
		return ret;
	}

	/*
	 * Get the enable GPIO. If any of the outputs is marked as being
	 * enabled at boot, request the GPIO with an initial high state to
	 * avoid disabling outputs that may have been turned on by the boot
	 * loader. Otherwise, request it with a low state to enter lower-power
	 * shutdown.
	 */
	flags = boot_on ? GPIOD_OUT_HIGH : GPIOD_OUT_LOW;
	chip->ena_gpiod = devm_gpiod_get(chip->dev, "enable", flags);
	if (IS_ERR(chip->ena_gpiod)) {
		ret = PTR_ERR(chip->ena_gpiod);
		dev_err(chip->dev, "Failed to get enable GPIO: %d\n", ret);
		return ret;
	}

	ret = max20086_regulators_register(chip);
	if (ret < 0) {
		dev_err(chip->dev, "Failed to register regulators: %d\n", ret);
		return ret;
	}

	return 0;
}

static const struct i2c_device_id max20086_i2c_id[] = {
	{ "max20086" },
	{ "max20087" },
	{ "max20088" },
	{ "max20089" },
	{ /* Sentinel */ },
};

MODULE_DEVICE_TABLE(i2c, max20086_i2c_id);

static const struct of_device_id max20086_dt_ids[] = {
	{
		.compatible = "maxim,max20086",
		.data = &(const struct max20086_chip_info) {
			.id = MAX20086_DEVICE_ID_MAX20086,
			.num_outputs = 4,
		}
	}, {
		.compatible = "maxim,max20087",
		.data = &(const struct max20086_chip_info) {
			.id = MAX20086_DEVICE_ID_MAX20087,
			.num_outputs = 4,
		}
	}, {
		.compatible = "maxim,max20088",
		.data = &(const struct max20086_chip_info) {
			.id = MAX20086_DEVICE_ID_MAX20088,
			.num_outputs = 2,
		}
	}, {
		.compatible = "maxim,max20089",
		.data = &(const struct max20086_chip_info) {
			.id = MAX20086_DEVICE_ID_MAX20089,
			.num_outputs = 2,
		}
	},
	{ /* Sentinel */ },
};

MODULE_DEVICE_TABLE(of, max20086_dt_ids);

static struct i2c_driver max20086_regulator_driver = {
	.driver = {
		.name = "max20086",
		.of_match_table = of_match_ptr(max20086_dt_ids),
	},
	.probe_new = max20086_i2c_probe,
	.id_table = max20086_i2c_id,
};

module_i2c_driver(max20086_regulator_driver);

MODULE_AUTHOR("Watson Chow <watson.chow@avnet.com>");
MODULE_DESCRIPTION("MAX20086-MAX20089 Camera Power Protector Driver");
MODULE_LICENSE("GPL");