// 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/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_percpu_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.fwnode = dev_fwnode(dev);
        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");