/*
 *  Copyright (C) 2017, Topic Embedded Products
 *  Driver for LTC3651 charger IC.
 *
 *  This program is free software; you can redistribute it and/or modify it
 *  under  the terms of the GNU General  Public License as published by the
 *  Free Software Foundation;  either version 2 of the License, or (at your
 *  option) any later version.
 */

#include <linux/device.h>
#include <linux/gpio/consumer.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/power_supply.h>
#include <linux/slab.h>
#include <linux/of.h>

struct ltc3651_charger {
	struct power_supply *charger;
	struct power_supply_desc charger_desc;
	struct gpio_desc *acpr_gpio;
	struct gpio_desc *fault_gpio;
	struct gpio_desc *chrg_gpio;
};

static irqreturn_t ltc3651_charger_irq(int irq, void *devid)
{
	struct power_supply *charger = devid;

	power_supply_changed(charger);

	return IRQ_HANDLED;
}

static inline struct ltc3651_charger *psy_to_ltc3651_charger(
	struct power_supply *psy)
{
	return power_supply_get_drvdata(psy);
}

static int ltc3651_charger_get_property(struct power_supply *psy,
		enum power_supply_property psp, union power_supply_propval *val)
{
	struct ltc3651_charger *ltc3651_charger = psy_to_ltc3651_charger(psy);

	switch (psp) {
	case POWER_SUPPLY_PROP_STATUS:
		if (!ltc3651_charger->chrg_gpio) {
			val->intval = POWER_SUPPLY_STATUS_UNKNOWN;
			break;
		}
		if (gpiod_get_value(ltc3651_charger->chrg_gpio))
			val->intval = POWER_SUPPLY_STATUS_CHARGING;
		else
			val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING;
		break;
	case POWER_SUPPLY_PROP_ONLINE:
		val->intval = gpiod_get_value(ltc3651_charger->acpr_gpio);
		break;
	case POWER_SUPPLY_PROP_HEALTH:
		if (!ltc3651_charger->fault_gpio) {
			val->intval = POWER_SUPPLY_HEALTH_UNKNOWN;
			break;
		}
		if (!gpiod_get_value(ltc3651_charger->fault_gpio)) {
			val->intval = POWER_SUPPLY_HEALTH_GOOD;
			break;
		}
		/*
		 * If the fault pin is active, the chrg pin explains the type
		 * of failure.
		 */
		if (!ltc3651_charger->chrg_gpio) {
			val->intval = POWER_SUPPLY_HEALTH_UNSPEC_FAILURE;
			break;
		}
		val->intval = gpiod_get_value(ltc3651_charger->chrg_gpio) ?
				POWER_SUPPLY_HEALTH_OVERHEAT :
				POWER_SUPPLY_HEALTH_DEAD;
		break;
	default:
		return -EINVAL;
	}

	return 0;
}

static enum power_supply_property ltc3651_charger_properties[] = {
	POWER_SUPPLY_PROP_STATUS,
	POWER_SUPPLY_PROP_ONLINE,
	POWER_SUPPLY_PROP_HEALTH,
};

static int ltc3651_charger_probe(struct platform_device *pdev)
{
	struct power_supply_config psy_cfg = {};
	struct ltc3651_charger *ltc3651_charger;
	struct power_supply_desc *charger_desc;
	int ret;

	ltc3651_charger = devm_kzalloc(&pdev->dev, sizeof(*ltc3651_charger),
					GFP_KERNEL);
	if (!ltc3651_charger)
		return -ENOMEM;

	ltc3651_charger->acpr_gpio = devm_gpiod_get(&pdev->dev,
					"lltc,acpr", GPIOD_IN);
	if (IS_ERR(ltc3651_charger->acpr_gpio)) {
		ret = PTR_ERR(ltc3651_charger->acpr_gpio);
		dev_err(&pdev->dev, "Failed to acquire acpr GPIO: %d\n", ret);
		return ret;
	}
	ltc3651_charger->fault_gpio = devm_gpiod_get_optional(&pdev->dev,
					"lltc,fault", GPIOD_IN);
	if (IS_ERR(ltc3651_charger->fault_gpio)) {
		ret = PTR_ERR(ltc3651_charger->fault_gpio);
		dev_err(&pdev->dev, "Failed to acquire fault GPIO: %d\n", ret);
		return ret;
	}
	ltc3651_charger->chrg_gpio = devm_gpiod_get_optional(&pdev->dev,
					"lltc,chrg", GPIOD_IN);
	if (IS_ERR(ltc3651_charger->chrg_gpio)) {
		ret = PTR_ERR(ltc3651_charger->chrg_gpio);
		dev_err(&pdev->dev, "Failed to acquire chrg GPIO: %d\n", ret);
		return ret;
	}

	charger_desc = &ltc3651_charger->charger_desc;
	charger_desc->name = pdev->dev.of_node->name;
	charger_desc->type = POWER_SUPPLY_TYPE_MAINS;
	charger_desc->properties = ltc3651_charger_properties;
	charger_desc->num_properties = ARRAY_SIZE(ltc3651_charger_properties);
	charger_desc->get_property = ltc3651_charger_get_property;
	psy_cfg.of_node = pdev->dev.of_node;
	psy_cfg.drv_data = ltc3651_charger;

	ltc3651_charger->charger = devm_power_supply_register(&pdev->dev,
						      charger_desc, &psy_cfg);
	if (IS_ERR(ltc3651_charger->charger)) {
		ret = PTR_ERR(ltc3651_charger->charger);
		dev_err(&pdev->dev, "Failed to register power supply: %d\n",
			ret);
		return ret;
	}

	/*
	 * Acquire IRQs for the GPIO pins if possible. If the system does not
	 * support IRQs on these pins, userspace will have to poll the sysfs
	 * files manually.
	 */
	if (ltc3651_charger->acpr_gpio) {
		ret = gpiod_to_irq(ltc3651_charger->acpr_gpio);
		if (ret >= 0)
			ret = devm_request_any_context_irq(&pdev->dev, ret,
				ltc3651_charger_irq,
				IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
				dev_name(&pdev->dev), ltc3651_charger->charger);
		if (ret < 0)
			dev_warn(&pdev->dev, "Failed to request acpr irq\n");
	}
	if (ltc3651_charger->fault_gpio) {
		ret = gpiod_to_irq(ltc3651_charger->fault_gpio);
		if (ret >= 0)
			ret = devm_request_any_context_irq(&pdev->dev, ret,
				ltc3651_charger_irq,
				IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
				dev_name(&pdev->dev), ltc3651_charger->charger);
		if (ret < 0)
			dev_warn(&pdev->dev, "Failed to request fault irq\n");
	}
	if (ltc3651_charger->chrg_gpio) {
		ret = gpiod_to_irq(ltc3651_charger->chrg_gpio);
		if (ret >= 0)
			ret = devm_request_any_context_irq(&pdev->dev, ret,
				ltc3651_charger_irq,
				IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
				dev_name(&pdev->dev), ltc3651_charger->charger);
		if (ret < 0)
			dev_warn(&pdev->dev, "Failed to request chrg irq\n");
	}

	platform_set_drvdata(pdev, ltc3651_charger);

	return 0;
}

static const struct of_device_id ltc3651_charger_match[] = {
	{ .compatible = "lltc,ltc3651-charger" },
	{ }
};
MODULE_DEVICE_TABLE(of, ltc3651_charger_match);

static struct platform_driver ltc3651_charger_driver = {
	.probe = ltc3651_charger_probe,
	.driver = {
		.name = "ltc3651-charger",
		.of_match_table = ltc3651_charger_match,
	},
};

module_platform_driver(ltc3651_charger_driver);

MODULE_AUTHOR("Mike Looijmans <mike.looijmans@topic.nl>");
MODULE_DESCRIPTION("Driver for LTC3651 charger");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:ltc3651-charger");