// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2023, Nikita Travkin <nikita@trvn.ru>
 */

#include <linux/errno.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/power_supply.h>
#include <linux/property.h>
#include <linux/regmap.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/timekeeping.h>
#include <linux/mod_devicetable.h>

#define PM8916_PERPH_TYPE 0x04
#define PM8916_BMS_VM_TYPE 0x020D

#define PM8916_SEC_ACCESS 0xD0
#define PM8916_SEC_MAGIC 0xA5

#define PM8916_BMS_VM_STATUS1 0x08
#define PM8916_BMS_VM_FSM_STATE(x) (((x) & 0b00111000) >> 3)
#define PM8916_BMS_VM_FSM_STATE_S2 0x2

#define PM8916_BMS_VM_MODE_CTL 0x40
#define PM8916_BMS_VM_MODE_FORCE_S3 (BIT(0) | BIT(1))
#define PM8916_BMS_VM_MODE_NORMAL (BIT(1) | BIT(3))

#define PM8916_BMS_VM_EN_CTL 0x46
#define PM8916_BMS_ENABLED BIT(7)

#define PM8916_BMS_VM_FIFO_LENGTH_CTL 0x47
#define PM8916_BMS_VM_S1_SAMPLE_INTERVAL_CTL 0x55
#define PM8916_BMS_VM_S2_SAMPLE_INTERVAL_CTL 0x56
#define PM8916_BMS_VM_S3_S7_OCV_DATA0 0x6A
#define PM8916_BMS_VM_BMS_FIFO_REG_0_LSB 0xC0

/* Using only 1 fifo is broken in hardware */
#define PM8916_BMS_VM_FIFO_COUNT 2 /* 2 .. 8 */

#define PM8916_BMS_VM_S1_SAMPLE_INTERVAL 10
#define PM8916_BMS_VM_S2_SAMPLE_INTERVAL 10

struct pm8916_bms_vm_battery {
        struct device *dev;
        struct power_supply *battery;
        struct power_supply_battery_info *info;
        struct regmap *regmap;
        unsigned int reg;
        unsigned int last_ocv;
        time64_t last_ocv_time;
        unsigned int vbat_now;
};

static int pm8916_bms_vm_battery_get_property(struct power_supply *psy,
                                              enum power_supply_property psp,
                                              union power_supply_propval *val)
{
        struct pm8916_bms_vm_battery *bat = power_supply_get_drvdata(psy);
        struct power_supply_battery_info *info = bat->info;
        int supplied;

        switch (psp) {
        case POWER_SUPPLY_PROP_STATUS:
                supplied = power_supply_am_i_supplied(psy);

                if (supplied < 0 && supplied != -ENODEV)
                        return supplied;
                else if (supplied && supplied != -ENODEV)
                        val->intval = POWER_SUPPLY_STATUS_CHARGING;
                else
                        val->intval = POWER_SUPPLY_STATUS_DISCHARGING;
                return 0;

        case POWER_SUPPLY_PROP_HEALTH:
                if (bat->vbat_now < info->voltage_min_design_uv)
                        val->intval = POWER_SUPPLY_HEALTH_DEAD;
                else if (bat->vbat_now > info->voltage_max_design_uv)
                        val->intval = POWER_SUPPLY_HEALTH_OVERVOLTAGE;
                else
                        val->intval = POWER_SUPPLY_HEALTH_GOOD;
                return 0;

        case POWER_SUPPLY_PROP_VOLTAGE_NOW:
                val->intval = bat->vbat_now;
                return 0;

        case POWER_SUPPLY_PROP_VOLTAGE_OCV:
                /*
                 * Hardware only reliably measures OCV when the system is off or suspended.
                 * We expose the last known OCV value on boot, invalidating it after 180 seconds.
                 */
                if (ktime_get_seconds() - bat->last_ocv_time > 180)
                        return -ENODATA;

                val->intval = bat->last_ocv;
                return 0;

        default:
                return -EINVAL;
        }
}

static enum power_supply_property pm8916_bms_vm_battery_properties[] = {
        POWER_SUPPLY_PROP_STATUS,
        POWER_SUPPLY_PROP_VOLTAGE_NOW,
        POWER_SUPPLY_PROP_VOLTAGE_OCV,
        POWER_SUPPLY_PROP_HEALTH,
};

static irqreturn_t pm8916_bms_vm_fifo_update_done_irq(int irq, void *data)
{
        struct pm8916_bms_vm_battery *bat = data;
        u16 vbat_data[PM8916_BMS_VM_FIFO_COUNT];
        int ret;

        ret = regmap_bulk_read(bat->regmap, bat->reg + PM8916_BMS_VM_BMS_FIFO_REG_0_LSB,
                               &vbat_data, PM8916_BMS_VM_FIFO_COUNT * 2);
        if (ret)
                return IRQ_HANDLED;

        /*
         * The VM-BMS hardware only collects voltage data and the software
         * has to process it to calculate the OCV and SoC. Hardware provides
         * up to 8 averaged measurements for software to take in account.
         *
         * Just use the last measured value for now to report the current
         * battery voltage.
         */
        bat->vbat_now = vbat_data[PM8916_BMS_VM_FIFO_COUNT - 1] * 300;

        power_supply_changed(bat->battery);

        return IRQ_HANDLED;
}

static const struct power_supply_desc pm8916_bms_vm_battery_psy_desc = {
        .name = "pm8916-bms-vm",
        .type = POWER_SUPPLY_TYPE_BATTERY,
        .properties = pm8916_bms_vm_battery_properties,
        .num_properties = ARRAY_SIZE(pm8916_bms_vm_battery_properties),
        .get_property = pm8916_bms_vm_battery_get_property,
};

static int pm8916_bms_vm_battery_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct pm8916_bms_vm_battery *bat;
        struct power_supply_config psy_cfg = {};
        int ret, irq;
        unsigned int tmp;

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

        bat->dev = dev;

        bat->regmap = dev_get_regmap(pdev->dev.parent, NULL);
        if (!bat->regmap)
                return -ENODEV;

        ret = device_property_read_u32(dev, "reg", &bat->reg);
        if (ret < 0)
                return -EINVAL;

        ret = regmap_bulk_read(bat->regmap, bat->reg + PM8916_PERPH_TYPE, &tmp, 2);
        if (ret)
                goto comm_error;

        if (tmp != PM8916_BMS_VM_TYPE)
                return dev_err_probe(dev, -ENODEV, "Device reported wrong type: 0x%X\n", tmp);

        ret = regmap_write(bat->regmap, bat->reg + PM8916_BMS_VM_S1_SAMPLE_INTERVAL_CTL,
                           PM8916_BMS_VM_S1_SAMPLE_INTERVAL);
        if (ret)
                goto comm_error;
        ret = regmap_write(bat->regmap, bat->reg + PM8916_BMS_VM_S2_SAMPLE_INTERVAL_CTL,
                           PM8916_BMS_VM_S2_SAMPLE_INTERVAL);
        if (ret)
                goto comm_error;
        ret = regmap_write(bat->regmap, bat->reg + PM8916_BMS_VM_FIFO_LENGTH_CTL,
                           PM8916_BMS_VM_FIFO_COUNT << 4 | PM8916_BMS_VM_FIFO_COUNT);
        if (ret)
                goto comm_error;
        ret = regmap_write(bat->regmap,
                           bat->reg + PM8916_BMS_VM_EN_CTL, PM8916_BMS_ENABLED);
        if (ret)
                goto comm_error;

        ret = regmap_bulk_read(bat->regmap,
                               bat->reg + PM8916_BMS_VM_S3_S7_OCV_DATA0, &tmp, 2);
        if (ret)
                goto comm_error;

        bat->last_ocv_time = ktime_get_seconds();
        bat->last_ocv = tmp * 300;
        bat->vbat_now = bat->last_ocv;

        psy_cfg.drv_data = bat;
        psy_cfg.fwnode = dev_fwnode(dev);

        bat->battery = devm_power_supply_register(dev, &pm8916_bms_vm_battery_psy_desc, &psy_cfg);
        if (IS_ERR(bat->battery))
                return dev_err_probe(dev, PTR_ERR(bat->battery), "Unable to register battery\n");

        ret = power_supply_get_battery_info(bat->battery, &bat->info);
        if (ret)
                return dev_err_probe(dev, ret, "Unable to get battery info\n");

        irq = platform_get_irq_byname(pdev, "fifo");
        if (irq < 0)
                return irq;

        ret = devm_request_threaded_irq(dev, irq, NULL, pm8916_bms_vm_fifo_update_done_irq,
                                        IRQF_ONESHOT, "pm8916_vm_bms", bat);
        if (ret)
                return ret;

        platform_set_drvdata(pdev, bat);

        return 0;

comm_error:
        return dev_err_probe(dev, ret, "Unable to communicate with device\n");
}

static int pm8916_bms_vm_battery_suspend(struct platform_device *pdev, pm_message_t state)
{
        struct pm8916_bms_vm_battery *bat = platform_get_drvdata(pdev);
        int ret;

        /*
         * Due to a hardware quirk the FSM doesn't switch states normally.
         * Instead we unlock the debug registers and force S3 (Measure OCV/Sleep)
         * mode every time we suspend.
         */

        ret = regmap_write(bat->regmap,
                           bat->reg + PM8916_SEC_ACCESS, PM8916_SEC_MAGIC);
        if (ret)
                goto error;
        ret = regmap_write(bat->regmap,
                           bat->reg + PM8916_BMS_VM_MODE_CTL, PM8916_BMS_VM_MODE_FORCE_S3);
        if (ret)
                goto error;

        return 0;

error:
        dev_err(bat->dev, "Failed to force S3 mode: %pe\n", ERR_PTR(ret));
        return ret;
}

static int pm8916_bms_vm_battery_resume(struct platform_device *pdev)
{
        struct pm8916_bms_vm_battery *bat = platform_get_drvdata(pdev);
        int ret;
        unsigned int tmp;

        ret = regmap_bulk_read(bat->regmap,
                               bat->reg + PM8916_BMS_VM_S3_S7_OCV_DATA0, &tmp, 2);

        bat->last_ocv_time = ktime_get_seconds();
        bat->last_ocv = tmp * 300;

        ret = regmap_write(bat->regmap,
                           bat->reg + PM8916_SEC_ACCESS, PM8916_SEC_MAGIC);
        if (ret)
                goto error;
        ret = regmap_write(bat->regmap,
                           bat->reg + PM8916_BMS_VM_MODE_CTL, PM8916_BMS_VM_MODE_NORMAL);
        if (ret)
                goto error;

        return 0;

error:
        dev_err(bat->dev, "Failed to return normal mode: %pe\n", ERR_PTR(ret));
        return ret;
}

static const struct of_device_id pm8916_bms_vm_battery_of_match[] = {
        { .compatible = "qcom,pm8916-bms-vm", },
        {}
};
MODULE_DEVICE_TABLE(of, pm8916_bms_vm_battery_of_match);

static struct platform_driver pm8916_bms_vm_battery_driver = {
        .driver = {
                .name = "pm8916-bms-vm",
                .of_match_table = pm8916_bms_vm_battery_of_match,
        },
        .probe = pm8916_bms_vm_battery_probe,
        .suspend = pm8916_bms_vm_battery_suspend,
        .resume = pm8916_bms_vm_battery_resume,
};
module_platform_driver(pm8916_bms_vm_battery_driver);

MODULE_DESCRIPTION("pm8916 BMS-VM driver");
MODULE_AUTHOR("Nikita Travkin <nikita@trvn.ru>");
MODULE_LICENSE("GPL");