// SPDX-License-Identifier: GPL-2.0+
/*
 * Onkey driver for Actions Semi ATC260x PMICs.
 *
 * Copyright (c) 2020 Cristian Ciocaltea <cristian.ciocaltea@gmail.com>
 */

#include <linux/bitfield.h>
#include <linux/input.h>
#include <linux/interrupt.h>
#include <linux/mfd/atc260x/core.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>

/* <2s for short press, >2s for long press */
#define KEY_PRESS_TIME_SEC      2

/* Driver internals */
enum atc260x_onkey_reset_status {
        KEY_RESET_HW_DEFAULT,
        KEY_RESET_DISABLED,
        KEY_RESET_USER_SEL,
};

struct atc260x_onkey_params {
        u32 reg_int_ctl;
        u32 kdwn_state_bm;
        u32 long_int_pnd_bm;
        u32 short_int_pnd_bm;
        u32 kdwn_int_pnd_bm;
        u32 press_int_en_bm;
        u32 kdwn_int_en_bm;
        u32 press_time_bm;
        u32 reset_en_bm;
        u32 reset_time_bm;
};

struct atc260x_onkey {
        struct atc260x *atc260x;
        const struct atc260x_onkey_params *params;
        struct input_dev *input_dev;
        struct delayed_work work;
        int irq;
};

static const struct atc260x_onkey_params atc2603c_onkey_params = {
        .reg_int_ctl            = ATC2603C_PMU_SYS_CTL2,
        .long_int_pnd_bm        = ATC2603C_PMU_SYS_CTL2_ONOFF_LONG_PRESS,
        .short_int_pnd_bm       = ATC2603C_PMU_SYS_CTL2_ONOFF_SHORT_PRESS,
        .kdwn_int_pnd_bm        = ATC2603C_PMU_SYS_CTL2_ONOFF_PRESS_PD,
        .press_int_en_bm        = ATC2603C_PMU_SYS_CTL2_ONOFF_INT_EN,
        .kdwn_int_en_bm         = ATC2603C_PMU_SYS_CTL2_ONOFF_PRESS_INT_EN,
        .kdwn_state_bm          = ATC2603C_PMU_SYS_CTL2_ONOFF_PRESS,
        .press_time_bm          = ATC2603C_PMU_SYS_CTL2_ONOFF_PRESS_TIME,
        .reset_en_bm            = ATC2603C_PMU_SYS_CTL2_ONOFF_PRESS_RESET_EN,
        .reset_time_bm          = ATC2603C_PMU_SYS_CTL2_ONOFF_RESET_TIME_SEL,
};

static const struct atc260x_onkey_params atc2609a_onkey_params = {
        .reg_int_ctl            = ATC2609A_PMU_SYS_CTL2,
        .long_int_pnd_bm        = ATC2609A_PMU_SYS_CTL2_ONOFF_LONG_PRESS,
        .short_int_pnd_bm       = ATC2609A_PMU_SYS_CTL2_ONOFF_SHORT_PRESS,
        .kdwn_int_pnd_bm        = ATC2609A_PMU_SYS_CTL2_ONOFF_PRESS_PD,
        .press_int_en_bm        = ATC2609A_PMU_SYS_CTL2_ONOFF_LSP_INT_EN,
        .kdwn_int_en_bm         = ATC2609A_PMU_SYS_CTL2_ONOFF_PRESS_INT_EN,
        .kdwn_state_bm          = ATC2609A_PMU_SYS_CTL2_ONOFF_PRESS,
        .press_time_bm          = ATC2609A_PMU_SYS_CTL2_ONOFF_PRESS_TIME,
        .reset_en_bm            = ATC2609A_PMU_SYS_CTL2_ONOFF_RESET_EN,
        .reset_time_bm          = ATC2609A_PMU_SYS_CTL2_ONOFF_RESET_TIME_SEL,
};

static int atc2603x_onkey_hw_init(struct atc260x_onkey *onkey,
                                  enum atc260x_onkey_reset_status reset_status,
                                  u32 reset_time, u32 press_time)
{
        u32 reg_bm, reg_val;

        reg_bm = onkey->params->long_int_pnd_bm |
                 onkey->params->short_int_pnd_bm |
                 onkey->params->kdwn_int_pnd_bm |
                 onkey->params->press_int_en_bm |
                 onkey->params->kdwn_int_en_bm;

        reg_val = reg_bm | press_time;
        reg_bm |= onkey->params->press_time_bm;

        if (reset_status == KEY_RESET_DISABLED) {
                reg_bm |= onkey->params->reset_en_bm;
        } else if (reset_status == KEY_RESET_USER_SEL) {
                reg_bm |= onkey->params->reset_en_bm |
                          onkey->params->reset_time_bm;
                reg_val |= onkey->params->reset_en_bm | reset_time;
        }

        return regmap_update_bits(onkey->atc260x->regmap,
                                  onkey->params->reg_int_ctl, reg_bm, reg_val);
}

static void atc260x_onkey_query(struct atc260x_onkey *onkey)
{
        u32 reg_bits;
        int ret, key_down;

        ret = regmap_read(onkey->atc260x->regmap,
                          onkey->params->reg_int_ctl, &key_down);
        if (ret) {
                key_down = 1;
                dev_err(onkey->atc260x->dev,
                        "Failed to read onkey status: %d\n", ret);
        } else {
                key_down &= onkey->params->kdwn_state_bm;
        }

        /*
         * The hardware generates interrupt only when the onkey pin is
         * asserted. Hence, the deassertion of the pin is simulated through
         * work queue.
         */
        if (key_down) {
                schedule_delayed_work(&onkey->work, msecs_to_jiffies(200));
                return;
        }

        /*
         * The key-down status bit is cleared when the On/Off button
         * is released.
         */
        input_report_key(onkey->input_dev, KEY_POWER, 0);
        input_sync(onkey->input_dev);

        reg_bits = onkey->params->long_int_pnd_bm |
                   onkey->params->short_int_pnd_bm |
                   onkey->params->kdwn_int_pnd_bm |
                   onkey->params->press_int_en_bm |
                   onkey->params->kdwn_int_en_bm;

        /* Clear key press pending events and enable key press interrupts. */
        regmap_update_bits(onkey->atc260x->regmap, onkey->params->reg_int_ctl,
                           reg_bits, reg_bits);
}

static void atc260x_onkey_work(struct work_struct *work)
{
        struct atc260x_onkey *onkey = container_of(work, struct atc260x_onkey,
                                                   work.work);
        atc260x_onkey_query(onkey);
}

static irqreturn_t atc260x_onkey_irq(int irq, void *data)
{
        struct atc260x_onkey *onkey = data;
        int ret;

        /* Disable key press interrupts. */
        ret = regmap_update_bits(onkey->atc260x->regmap,
                                 onkey->params->reg_int_ctl,
                                 onkey->params->press_int_en_bm |
                                 onkey->params->kdwn_int_en_bm, 0);
        if (ret)
                dev_err(onkey->atc260x->dev,
                        "Failed to disable interrupts: %d\n", ret);

        input_report_key(onkey->input_dev, KEY_POWER, 1);
        input_sync(onkey->input_dev);

        atc260x_onkey_query(onkey);

        return IRQ_HANDLED;
}

static int atc260x_onkey_open(struct input_dev *dev)
{
        struct atc260x_onkey *onkey = input_get_drvdata(dev);

        enable_irq(onkey->irq);

        return 0;
}

static void atc260x_onkey_close(struct input_dev *dev)
{
        struct atc260x_onkey *onkey = input_get_drvdata(dev);

        disable_irq(onkey->irq);
        cancel_delayed_work_sync(&onkey->work);
}

static int atc260x_onkey_probe(struct platform_device *pdev)
{
        struct atc260x *atc260x = dev_get_drvdata(pdev->dev.parent);
        struct atc260x_onkey *onkey;
        struct input_dev *input_dev;
        enum atc260x_onkey_reset_status reset_status;
        u32 press_time = KEY_PRESS_TIME_SEC, reset_time = 0;
        int val, error;

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

        error = device_property_read_u32(pdev->dev.parent,
                                         "reset-time-sec", &val);
        if (error) {
                reset_status = KEY_RESET_HW_DEFAULT;
        } else if (val) {
                if (val < 6 || val > 12) {
                        dev_err(&pdev->dev, "reset-time-sec out of range\n");
                        return -EINVAL;
                }

                reset_status = KEY_RESET_USER_SEL;
                reset_time = (val - 6) / 2;
        } else {
                reset_status = KEY_RESET_DISABLED;
                dev_dbg(&pdev->dev, "Disabled reset on long-press\n");
        }

        switch (atc260x->ic_type) {
        case ATC2603C:
                onkey->params = &atc2603c_onkey_params;
                press_time = FIELD_PREP(ATC2603C_PMU_SYS_CTL2_ONOFF_PRESS_TIME,
                                        press_time);
                reset_time = FIELD_PREP(ATC2603C_PMU_SYS_CTL2_ONOFF_RESET_TIME_SEL,
                                        reset_time);
                break;
        case ATC2609A:
                onkey->params = &atc2609a_onkey_params;
                press_time = FIELD_PREP(ATC2609A_PMU_SYS_CTL2_ONOFF_PRESS_TIME,
                                        press_time);
                reset_time = FIELD_PREP(ATC2609A_PMU_SYS_CTL2_ONOFF_RESET_TIME_SEL,
                                        reset_time);
                break;
        default:
                dev_err(&pdev->dev,
                        "OnKey not supported for ATC260x PMIC type: %u\n",
                        atc260x->ic_type);
                return -EINVAL;
        }

        input_dev = devm_input_allocate_device(&pdev->dev);
        if (!input_dev) {
                dev_err(&pdev->dev, "Failed to allocate input device\n");
                return -ENOMEM;
        }

        onkey->input_dev = input_dev;
        onkey->atc260x = atc260x;

        input_dev->name = "atc260x-onkey";
        input_dev->phys = "atc260x-onkey/input0";
        input_dev->open = atc260x_onkey_open;
        input_dev->close = atc260x_onkey_close;

        input_set_capability(input_dev, EV_KEY, KEY_POWER);
        input_set_drvdata(input_dev, onkey);

        INIT_DELAYED_WORK(&onkey->work, atc260x_onkey_work);

        onkey->irq = platform_get_irq(pdev, 0);
        if (onkey->irq < 0)
                return onkey->irq;

        error = devm_request_threaded_irq(&pdev->dev, onkey->irq, NULL,
                                          atc260x_onkey_irq, IRQF_ONESHOT,
                                          dev_name(&pdev->dev), onkey);
        if (error) {
                dev_err(&pdev->dev,
                        "Failed to register IRQ %d: %d\n", onkey->irq, error);
                return error;
        }

        /* Keep IRQ disabled until atc260x_onkey_open() is called. */
        disable_irq(onkey->irq);

        error = input_register_device(input_dev);
        if (error) {
                dev_err(&pdev->dev,
                        "Failed to register input device: %d\n", error);
                return error;
        }

        error = atc2603x_onkey_hw_init(onkey, reset_status,
                                       reset_time, press_time);
        if (error)
                return error;

        device_init_wakeup(&pdev->dev, true);

        return 0;
}

static struct platform_driver atc260x_onkey_driver = {
        .probe  = atc260x_onkey_probe,
        .driver = {
                .name = "atc260x-onkey",
        },
};

module_platform_driver(atc260x_onkey_driver);

MODULE_DESCRIPTION("Onkey driver for ATC260x PMICs");
MODULE_AUTHOR("Cristian Ciocaltea <cristian.ciocaltea@gmail.com>");
MODULE_LICENSE("GPL");