// SPDX-License-Identifier: GPL-2.0+
/*
 * Driver for UCS1002 Programmable USB Port Power Controller
 *
 * Copyright (C) 2019 Zodiac Inflight Innovations
 */
#include <linux/bits.h>
#include <linux/freezer.h>
#include <linux/gpio/consumer.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/power_supply.h>
#include <linux/regmap.h>
#include <linux/regulator/driver.h>
#include <linux/regulator/of_regulator.h>

/* UCS1002 Registers */
#define UCS1002_REG_CURRENT_MEASUREMENT	0x00

/*
 * The Total Accumulated Charge registers store the total accumulated
 * charge delivered from the VS source to a portable device. The total
 * value is calculated using four registers, from 01h to 04h. The bit
 * weighting of the registers is given in mA/hrs.
 */
#define UCS1002_REG_TOTAL_ACC_CHARGE	0x01

/* Other Status Register */
#define UCS1002_REG_OTHER_STATUS	0x0f
#  define F_ADET_PIN			BIT(4)
#  define F_CHG_ACT			BIT(3)

/* Interrupt Status */
#define UCS1002_REG_INTERRUPT_STATUS	0x10
#  define F_ERR				BIT(7)
#  define F_DISCHARGE_ERR		BIT(6)
#  define F_RESET			BIT(5)
#  define F_MIN_KEEP_OUT		BIT(4)
#  define F_TSD				BIT(3)
#  define F_OVER_VOLT			BIT(2)
#  define F_BACK_VOLT			BIT(1)
#  define F_OVER_ILIM			BIT(0)

/* Pin Status Register */
#define UCS1002_REG_PIN_STATUS		0x14
#  define UCS1002_PWR_STATE_MASK	0x03
#  define F_PWR_EN_PIN			BIT(6)
#  define F_M2_PIN			BIT(5)
#  define F_M1_PIN			BIT(4)
#  define F_EM_EN_PIN			BIT(3)
#  define F_SEL_PIN			BIT(2)
#  define F_ACTIVE_MODE_MASK		GENMASK(5, 3)
#  define F_ACTIVE_MODE_PASSTHROUGH	F_M2_PIN
#  define F_ACTIVE_MODE_DEDICATED	F_EM_EN_PIN
#  define F_ACTIVE_MODE_BC12_DCP	(F_M2_PIN | F_EM_EN_PIN)
#  define F_ACTIVE_MODE_BC12_SDP	F_M1_PIN
#  define F_ACTIVE_MODE_BC12_CDP	(F_M1_PIN | F_M2_PIN | F_EM_EN_PIN)

/* General Configuration Register */
#define UCS1002_REG_GENERAL_CFG		0x15
#  define F_RATION_EN			BIT(3)

/* Emulation Configuration Register */
#define UCS1002_REG_EMU_CFG		0x16

/* Switch Configuration Register */
#define UCS1002_REG_SWITCH_CFG		0x17
#  define F_PIN_IGNORE			BIT(7)
#  define F_EM_EN_SET			BIT(5)
#  define F_M2_SET			BIT(4)
#  define F_M1_SET			BIT(3)
#  define F_S0_SET			BIT(2)
#  define F_PWR_EN_SET			BIT(1)
#  define F_LATCH_SET			BIT(0)
#  define V_SET_ACTIVE_MODE_MASK	GENMASK(5, 3)
#  define V_SET_ACTIVE_MODE_PASSTHROUGH	F_M2_SET
#  define V_SET_ACTIVE_MODE_DEDICATED	F_EM_EN_SET
#  define V_SET_ACTIVE_MODE_BC12_DCP	(F_M2_SET | F_EM_EN_SET)
#  define V_SET_ACTIVE_MODE_BC12_SDP	F_M1_SET
#  define V_SET_ACTIVE_MODE_BC12_CDP	(F_M1_SET | F_M2_SET | F_EM_EN_SET)

/* Current Limit Register */
#define UCS1002_REG_ILIMIT		0x19
#  define UCS1002_ILIM_SW_MASK		GENMASK(3, 0)

/* Product ID */
#define UCS1002_REG_PRODUCT_ID		0xfd
#  define UCS1002_PRODUCT_ID		0x4e

/* Manufacture name */
#define UCS1002_MANUFACTURER		"SMSC"

struct ucs1002_info {
	struct power_supply *charger;
	struct i2c_client *client;
	struct regmap *regmap;
	struct regulator_desc *regulator_descriptor;
	struct regulator_dev *rdev;
	bool present;
	bool output_disable;
	struct delayed_work health_poll;
	int health;

};

static enum power_supply_property ucs1002_props[] = {
	POWER_SUPPLY_PROP_ONLINE,
	POWER_SUPPLY_PROP_CHARGE_NOW,
	POWER_SUPPLY_PROP_CURRENT_NOW,
	POWER_SUPPLY_PROP_CURRENT_MAX,
	POWER_SUPPLY_PROP_PRESENT, /* the presence of PED */
	POWER_SUPPLY_PROP_MANUFACTURER,
	POWER_SUPPLY_PROP_USB_TYPE,
	POWER_SUPPLY_PROP_HEALTH,
};

static int ucs1002_get_online(struct ucs1002_info *info,
			      union power_supply_propval *val)
{
	unsigned int reg;
	int ret;

	ret = regmap_read(info->regmap, UCS1002_REG_OTHER_STATUS, &reg);
	if (ret)
		return ret;

	val->intval = !!(reg & F_CHG_ACT);

	return 0;
}

static int ucs1002_get_charge(struct ucs1002_info *info,
			      union power_supply_propval *val)
{
	/*
	 * To fit within 32 bits some values are rounded (uA/h)
	 *
	 * For Total Accumulated Charge Middle Low Byte register, addr
	 * 03h, byte 2
	 *
	 *   B0: 0.01084 mA/h rounded to 11 uA/h
	 *   B1: 0.02169 mA/h rounded to 22 uA/h
	 *   B2: 0.04340 mA/h rounded to 43 uA/h
	 *   B3: 0.08676 mA/h rounded to 87 uA/h
	 *   B4: 0.17350 mA/h rounded to 173 uÁ/h
	 *
	 * For Total Accumulated Charge Low Byte register, addr 04h,
	 * byte 3
	 *
	 *   B6: 0.00271 mA/h rounded to 3 uA/h
	 *   B7: 0.005422 mA/h rounded to 5 uA/h
	 */
	static const int bit_weights_uAh[BITS_PER_TYPE(u32)] = {
		/*
		 * Bit corresponding to low byte (offset 0x04)
		 * B0 B1 B2 B3 B4 B5 B6 B7
		 */
		0, 0, 0, 0, 0, 0, 3, 5,
		/*
		 * Bit corresponding to middle low byte (offset 0x03)
		 * B0 B1 B2 B3 B4 B5 B6 B7
		 */
		11, 22, 43, 87, 173, 347, 694, 1388,
		/*
		 * Bit corresponding to middle high byte (offset 0x02)
		 * B0 B1 B2 B3 B4 B5 B6 B7
		 */
		2776, 5552, 11105, 22210, 44420, 88840, 177700, 355400,
		/*
		 * Bit corresponding to high byte (offset 0x01)
		 * B0 B1 B2 B3 B4 B5 B6 B7
		 */
		710700, 1421000, 2843000, 5685000, 11371000, 22742000,
		45484000, 90968000,
	};
	unsigned long total_acc_charger;
	unsigned int reg;
	int i, ret;

	ret = regmap_bulk_read(info->regmap, UCS1002_REG_TOTAL_ACC_CHARGE,
			       &reg, sizeof(u32));
	if (ret)
		return ret;

	total_acc_charger = be32_to_cpu(reg); /* BE as per offsets above */
	val->intval = 0;

	for_each_set_bit(i, &total_acc_charger, ARRAY_SIZE(bit_weights_uAh))
		val->intval += bit_weights_uAh[i];

	return 0;
}

static int ucs1002_get_current(struct ucs1002_info *info,
			       union power_supply_propval *val)
{
	/*
	 * The Current Measurement register stores the measured
	 * current value delivered to the portable device. The range
	 * is from 9.76 mA to 2.5 A.
	 */
	static const int bit_weights_uA[BITS_PER_TYPE(u8)] = {
		9760, 19500, 39000, 78100, 156200, 312300, 624600, 1249300,
	};
	unsigned long current_measurement;
	unsigned int reg;
	int i, ret;

	ret = regmap_read(info->regmap, UCS1002_REG_CURRENT_MEASUREMENT, &reg);
	if (ret)
		return ret;

	current_measurement = reg;
	val->intval = 0;

	for_each_set_bit(i, &current_measurement, ARRAY_SIZE(bit_weights_uA))
		val->intval += bit_weights_uA[i];

	return 0;
}

/*
 * The Current Limit register stores the maximum current used by the
 * port switch. The range is from 500mA to 2.5 A.
 */
static const u32 ucs1002_current_limit_uA[] = {
	500000, 900000, 1000000, 1200000, 1500000, 1800000, 2000000, 2500000,
};

static int ucs1002_get_max_current(struct ucs1002_info *info,
				   union power_supply_propval *val)
{
	unsigned int reg;
	int ret;

	if (info->output_disable) {
		val->intval = 0;
		return 0;
	}

	ret = regmap_read(info->regmap, UCS1002_REG_ILIMIT, &reg);
	if (ret)
		return ret;

	val->intval = ucs1002_current_limit_uA[reg & UCS1002_ILIM_SW_MASK];

	return 0;
}

static int ucs1002_set_max_current(struct ucs1002_info *info, u32 val)
{
	unsigned int reg;
	int ret, idx;

	if (val == 0) {
		info->output_disable = true;
		regulator_disable_regmap(info->rdev);
		return 0;
	}

	for (idx = 0; idx < ARRAY_SIZE(ucs1002_current_limit_uA); idx++) {
		if (val == ucs1002_current_limit_uA[idx])
			break;
	}

	if (idx == ARRAY_SIZE(ucs1002_current_limit_uA))
		return -EINVAL;

	ret = regmap_write(info->regmap, UCS1002_REG_ILIMIT, idx);
	if (ret)
		return ret;
	/*
	 * Any current limit setting exceeding the one set via ILIM
	 * pin will be rejected, so we read out freshly changed limit
	 * to make sure that it took effect.
	 */
	ret = regmap_read(info->regmap, UCS1002_REG_ILIMIT, &reg);
	if (ret)
		return ret;

	if (reg != idx)
		return -EINVAL;

	info->output_disable = false;

	if (info->rdev && info->rdev->use_count &&
	    !regulator_is_enabled_regmap(info->rdev))
		regulator_enable_regmap(info->rdev);

	return 0;
}

static int ucs1002_set_usb_type(struct ucs1002_info *info, int val)
{
	unsigned int mode;

	switch (val) {
	/*
	 * POWER_SUPPLY_USB_TYPE_UNKNOWN == 0, map this to dedicated for
	 * userspace API compatibility with older versions of this driver
	 * which mapped 0 to dedicated.
	 */
	case POWER_SUPPLY_USB_TYPE_UNKNOWN:
	case POWER_SUPPLY_USB_TYPE_PD:
		mode = V_SET_ACTIVE_MODE_DEDICATED;
		break;
	case POWER_SUPPLY_USB_TYPE_SDP:
		mode = V_SET_ACTIVE_MODE_BC12_SDP;
		break;
	case POWER_SUPPLY_USB_TYPE_DCP:
		mode = V_SET_ACTIVE_MODE_BC12_DCP;
		break;
	case POWER_SUPPLY_USB_TYPE_CDP:
		mode = V_SET_ACTIVE_MODE_BC12_CDP;
		break;
	default:
		return -EINVAL;
	}

	return regmap_update_bits(info->regmap, UCS1002_REG_SWITCH_CFG,
				  V_SET_ACTIVE_MODE_MASK, mode);
}

static int ucs1002_get_usb_type(struct ucs1002_info *info,
				union power_supply_propval *val)
{
	enum power_supply_usb_type type;
	unsigned int reg;
	int ret;

	ret = regmap_read(info->regmap, UCS1002_REG_PIN_STATUS, &reg);
	if (ret)
		return ret;

	switch (reg & F_ACTIVE_MODE_MASK) {
	default:
		type = POWER_SUPPLY_USB_TYPE_UNKNOWN;
		break;
	case F_ACTIVE_MODE_DEDICATED:
		type = POWER_SUPPLY_USB_TYPE_PD;
		break;
	case F_ACTIVE_MODE_BC12_SDP:
		type = POWER_SUPPLY_USB_TYPE_SDP;
		break;
	case F_ACTIVE_MODE_BC12_DCP:
		type = POWER_SUPPLY_USB_TYPE_DCP;
		break;
	case F_ACTIVE_MODE_BC12_CDP:
		type = POWER_SUPPLY_USB_TYPE_CDP;
		break;
	}

	val->intval = type;

	return 0;
}

static int ucs1002_get_property(struct power_supply *psy,
				enum power_supply_property psp,
				union power_supply_propval *val)
{
	struct ucs1002_info *info = power_supply_get_drvdata(psy);

	switch (psp) {
	case POWER_SUPPLY_PROP_ONLINE:
		return ucs1002_get_online(info, val);
	case POWER_SUPPLY_PROP_CHARGE_NOW:
		return ucs1002_get_charge(info, val);
	case POWER_SUPPLY_PROP_CURRENT_NOW:
		return ucs1002_get_current(info, val);
	case POWER_SUPPLY_PROP_CURRENT_MAX:
		return ucs1002_get_max_current(info, val);
	case POWER_SUPPLY_PROP_USB_TYPE:
		return ucs1002_get_usb_type(info, val);
	case POWER_SUPPLY_PROP_HEALTH:
		val->intval = info->health;
		return 0;
	case POWER_SUPPLY_PROP_PRESENT:
		val->intval = info->present;
		return 0;
	case POWER_SUPPLY_PROP_MANUFACTURER:
		val->strval = UCS1002_MANUFACTURER;
		return 0;
	default:
		return -EINVAL;
	}
}

static int ucs1002_set_property(struct power_supply *psy,
				enum power_supply_property psp,
				const union power_supply_propval *val)
{
	struct ucs1002_info *info = power_supply_get_drvdata(psy);

	switch (psp) {
	case POWER_SUPPLY_PROP_CURRENT_MAX:
		return ucs1002_set_max_current(info, val->intval);
	case POWER_SUPPLY_PROP_USB_TYPE:
		return ucs1002_set_usb_type(info, val->intval);
	default:
		return -EINVAL;
	}
}

static int ucs1002_property_is_writeable(struct power_supply *psy,
					 enum power_supply_property psp)
{
	switch (psp) {
	case POWER_SUPPLY_PROP_CURRENT_MAX:
	case POWER_SUPPLY_PROP_USB_TYPE:
		return true;
	default:
		return false;
	}
}

static const struct power_supply_desc ucs1002_charger_desc = {
	.name			= "ucs1002",
	.type			= POWER_SUPPLY_TYPE_USB,
	.usb_types		= BIT(POWER_SUPPLY_USB_TYPE_SDP) |
				  BIT(POWER_SUPPLY_USB_TYPE_CDP) |
				  BIT(POWER_SUPPLY_USB_TYPE_DCP) |
				  BIT(POWER_SUPPLY_USB_TYPE_PD)  |
				  BIT(POWER_SUPPLY_USB_TYPE_UNKNOWN),
	.get_property		= ucs1002_get_property,
	.set_property		= ucs1002_set_property,
	.property_is_writeable	= ucs1002_property_is_writeable,
	.properties		= ucs1002_props,
	.num_properties		= ARRAY_SIZE(ucs1002_props),
};

static void ucs1002_health_poll(struct work_struct *work)
{
	struct ucs1002_info *info = container_of(work, struct ucs1002_info,
						 health_poll.work);
	int ret;
	u32 reg;

	ret = regmap_read(info->regmap, UCS1002_REG_INTERRUPT_STATUS, &reg);
	if (ret)
		return;

	/* bad health and no status change, just schedule us again in a while */
	if ((reg & F_ERR) && info->health != POWER_SUPPLY_HEALTH_GOOD) {
		schedule_delayed_work(&info->health_poll,
				      msecs_to_jiffies(2000));
		return;
	}

	if (reg & F_TSD)
		info->health = POWER_SUPPLY_HEALTH_OVERHEAT;
	else if (reg & (F_OVER_VOLT | F_BACK_VOLT))
		info->health = POWER_SUPPLY_HEALTH_OVERVOLTAGE;
	else if (reg & F_OVER_ILIM)
		info->health = POWER_SUPPLY_HEALTH_OVERCURRENT;
	else if (reg & (F_DISCHARGE_ERR | F_MIN_KEEP_OUT))
		info->health = POWER_SUPPLY_HEALTH_UNSPEC_FAILURE;
	else
		info->health = POWER_SUPPLY_HEALTH_GOOD;

	sysfs_notify(&info->charger->dev.kobj, NULL, "health");
}

static irqreturn_t ucs1002_charger_irq(int irq, void *data)
{
	int ret, regval;
	bool present;
	struct ucs1002_info *info = data;

	present = info->present;

	ret = regmap_read(info->regmap, UCS1002_REG_OTHER_STATUS, &regval);
	if (ret)
		return IRQ_HANDLED;

	/* update attached status */
	info->present = regval & F_ADET_PIN;

	/* notify the change */
	if (present != info->present)
		power_supply_changed(info->charger);

	return IRQ_HANDLED;
}

static irqreturn_t ucs1002_alert_irq(int irq, void *data)
{
	struct ucs1002_info *info = data;

	mod_delayed_work(system_wq, &info->health_poll, 0);

	return IRQ_HANDLED;
}

static int ucs1002_regulator_enable(struct regulator_dev *rdev)
{
	struct ucs1002_info *info = rdev_get_drvdata(rdev);

	/*
	 * If the output is disabled due to 0 maximum current, just pretend the
	 * enable did work. The regulator will be enabled as soon as we get a
	 * a non-zero maximum current budget.
	 */
	if (info->output_disable)
		return 0;

	return regulator_enable_regmap(rdev);
}

static const struct regulator_ops ucs1002_regulator_ops = {
	.is_enabled	= regulator_is_enabled_regmap,
	.enable		= ucs1002_regulator_enable,
	.disable	= regulator_disable_regmap,
};

static const struct regulator_desc ucs1002_regulator_descriptor = {
	.name		= "ucs1002-vbus",
	.ops		= &ucs1002_regulator_ops,
	.type		= REGULATOR_VOLTAGE,
	.owner		= THIS_MODULE,
	.enable_reg	= UCS1002_REG_SWITCH_CFG,
	.enable_mask	= F_PWR_EN_SET,
	.enable_val	= F_PWR_EN_SET,
	.fixed_uV	= 5000000,
	.n_voltages	= 1,
};

static int ucs1002_probe(struct i2c_client *client)
{
	struct device *dev = &client->dev;
	struct power_supply_config charger_config = {};
	const struct regmap_config regmap_config = {
		.reg_bits = 8,
		.val_bits = 8,
	};
	struct regulator_config regulator_config = {};
	int irq_a_det, irq_alert, ret;
	struct ucs1002_info *info;
	unsigned int regval;

	info = devm_kzalloc(dev, sizeof(*info), GFP_KERNEL);
	if (!info)
		return -ENOMEM;

	info->regmap = devm_regmap_init_i2c(client, &regmap_config);
	ret = PTR_ERR_OR_ZERO(info->regmap);
	if (ret) {
		dev_err(dev, "Regmap initialization failed: %d\n", ret);
		return ret;
	}

	info->client = client;

	irq_a_det = of_irq_get_byname(dev->of_node, "a_det");
	irq_alert = of_irq_get_byname(dev->of_node, "alert");

	charger_config.of_node = dev->of_node;
	charger_config.drv_data = info;

	ret = regmap_read(info->regmap, UCS1002_REG_PRODUCT_ID, &regval);
	if (ret) {
		dev_err(dev, "Failed to read product ID: %d\n", ret);
		return ret;
	}

	if (regval != UCS1002_PRODUCT_ID) {
		dev_err(dev,
			"Product ID does not match (0x%02x != 0x%02x)\n",
			regval, UCS1002_PRODUCT_ID);
		return -ENODEV;
	}

	/* Enable charge rationing by default */
	ret = regmap_update_bits(info->regmap, UCS1002_REG_GENERAL_CFG,
				 F_RATION_EN, F_RATION_EN);
	if (ret) {
		dev_err(dev, "Failed to read general config: %d\n", ret);
		return ret;
	}

	/*
	 * Ignore the M1, M2, PWR_EN, and EM_EN pin states. Set active
	 * mode selection to BC1.2 CDP.
	 */
	ret = regmap_update_bits(info->regmap, UCS1002_REG_SWITCH_CFG,
				 V_SET_ACTIVE_MODE_MASK | F_PIN_IGNORE,
				 V_SET_ACTIVE_MODE_BC12_CDP | F_PIN_IGNORE);
	if (ret) {
		dev_err(dev, "Failed to configure default mode: %d\n", ret);
		return ret;
	}
	/*
	 * Be safe and set initial current limit to 500mA
	 */
	ret = ucs1002_set_max_current(info, 500000);
	if (ret) {
		dev_err(dev, "Failed to set max current default: %d\n", ret);
		return ret;
	}

	info->charger = devm_power_supply_register(dev, &ucs1002_charger_desc,
						   &charger_config);
	ret = PTR_ERR_OR_ZERO(info->charger);
	if (ret) {
		dev_err(dev, "Failed to register power supply: %d\n", ret);
		return ret;
	}

	ret = regmap_read(info->regmap, UCS1002_REG_PIN_STATUS, &regval);
	if (ret) {
		dev_err(dev, "Failed to read pin status: %d\n", ret);
		return ret;
	}

	info->regulator_descriptor =
		devm_kmemdup(dev, &ucs1002_regulator_descriptor,
			     sizeof(ucs1002_regulator_descriptor),
			     GFP_KERNEL);
	if (!info->regulator_descriptor)
		return -ENOMEM;

	info->regulator_descriptor->enable_is_inverted = !(regval & F_SEL_PIN);

	regulator_config.dev = dev;
	regulator_config.of_node = dev->of_node;
	regulator_config.regmap = info->regmap;
	regulator_config.driver_data = info;

	info->rdev = devm_regulator_register(dev, info->regulator_descriptor,
				       &regulator_config);
	ret = PTR_ERR_OR_ZERO(info->rdev);
	if (ret) {
		dev_err(dev, "Failed to register VBUS regulator: %d\n", ret);
		return ret;
	}

	info->health = POWER_SUPPLY_HEALTH_GOOD;
	INIT_DELAYED_WORK(&info->health_poll, ucs1002_health_poll);

	if (irq_a_det > 0) {
		ret = devm_request_threaded_irq(dev, irq_a_det, NULL,
						ucs1002_charger_irq,
						IRQF_ONESHOT,
						"ucs1002-a_det", info);
		if (ret) {
			dev_err(dev, "Failed to request A_DET threaded irq: %d\n",
				ret);
			return ret;
		}
	}

	if (irq_alert > 0) {
		ret = devm_request_irq(dev, irq_alert, ucs1002_alert_irq,
				       0,"ucs1002-alert", info);
		if (ret) {
			dev_err(dev, "Failed to request ALERT threaded irq: %d\n",
				ret);
			return ret;
		}
	}

	return 0;
}

static const struct of_device_id ucs1002_of_match[] = {
	{ .compatible = "microchip,ucs1002", },
	{ /* sentinel */ },
};
MODULE_DEVICE_TABLE(of, ucs1002_of_match);

static struct i2c_driver ucs1002_driver = {
	.driver = {
		   .name = "ucs1002",
		   .of_match_table = ucs1002_of_match,
	},
	.probe = ucs1002_probe,
};
module_i2c_driver(ucs1002_driver);

MODULE_DESCRIPTION("Microchip UCS1002 Programmable USB Port Power Controller");
MODULE_AUTHOR("Enric Balletbo Serra <enric.balletbo@collabora.com>");
MODULE_AUTHOR("Andrey Smirnov <andrew.smirnov@gmail.com>");
MODULE_LICENSE("GPL");