// SPDX-License-Identifier: GPL-2.0+
/*
 * Azoteq IQS620A/621/622/624/625 Keys and Switches
 *
 * Copyright (C) 2019 Jeff LaBundy <jeff@labundy.com>
 */

#include <linux/device.h>
#include <linux/input.h>
#include <linux/kernel.h>
#include <linux/mfd/iqs62x.h>
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/regmap.h>
#include <linux/slab.h>

enum {
        IQS62X_SW_HALL_N,
        IQS62X_SW_HALL_S,
};

static const char * const iqs62x_switch_names[] = {
        [IQS62X_SW_HALL_N] = "hall-switch-north",
        [IQS62X_SW_HALL_S] = "hall-switch-south",
};

struct iqs62x_switch_desc {
        enum iqs62x_event_flag flag;
        unsigned int code;
        bool enabled;
};

struct iqs62x_keys_private {
        struct iqs62x_core *iqs62x;
        struct input_dev *input;
        struct notifier_block notifier;
        struct iqs62x_switch_desc switches[ARRAY_SIZE(iqs62x_switch_names)];
        unsigned int keycode[IQS62X_NUM_KEYS];
        unsigned int keycodemax;
        u8 interval;
};

static int iqs62x_keys_parse_prop(struct platform_device *pdev,
                                  struct iqs62x_keys_private *iqs62x_keys)
{
        unsigned int val;
        int ret, i;

        ret = device_property_count_u32(&pdev->dev, "linux,keycodes");
        if (ret > IQS62X_NUM_KEYS) {
                dev_err(&pdev->dev, "Too many keycodes present\n");
                return -EINVAL;
        } else if (ret < 0) {
                dev_err(&pdev->dev, "Failed to count keycodes: %d\n", ret);
                return ret;
        }
        iqs62x_keys->keycodemax = ret;

        ret = device_property_read_u32_array(&pdev->dev, "linux,keycodes",
                                             iqs62x_keys->keycode,
                                             iqs62x_keys->keycodemax);
        if (ret) {
                dev_err(&pdev->dev, "Failed to read keycodes: %d\n", ret);
                return ret;
        }

        for (i = 0; i < ARRAY_SIZE(iqs62x_keys->switches); i++) {
                struct fwnode_handle *child __free(fwnode_handle) =
                        device_get_named_child_node(&pdev->dev,
                                                    iqs62x_switch_names[i]);
                if (!child)
                        continue;

                ret = fwnode_property_read_u32(child, "linux,code", &val);
                if (ret) {
                        dev_err(&pdev->dev, "Failed to read switch code: %d\n",
                                ret);
                        return ret;
                }
                iqs62x_keys->switches[i].code = val;
                iqs62x_keys->switches[i].enabled = true;

                if (fwnode_property_present(child, "azoteq,use-prox"))
                        iqs62x_keys->switches[i].flag = (i == IQS62X_SW_HALL_N ?
                                                         IQS62X_EVENT_HALL_N_P :
                                                         IQS62X_EVENT_HALL_S_P);
                else
                        iqs62x_keys->switches[i].flag = (i == IQS62X_SW_HALL_N ?
                                                         IQS62X_EVENT_HALL_N_T :
                                                         IQS62X_EVENT_HALL_S_T);
        }

        return 0;
}

static int iqs62x_keys_init(struct iqs62x_keys_private *iqs62x_keys)
{
        struct iqs62x_core *iqs62x = iqs62x_keys->iqs62x;
        enum iqs62x_event_flag flag;
        unsigned int event_reg, val;
        unsigned int event_mask = 0;
        int ret, i;

        switch (iqs62x->dev_desc->prod_num) {
        case IQS620_PROD_NUM:
        case IQS621_PROD_NUM:
        case IQS622_PROD_NUM:
                event_reg = IQS620_GLBL_EVENT_MASK;

                /*
                 * Discreet button, hysteresis and SAR UI flags represent keys
                 * and are unmasked if mapped to a valid keycode.
                 */
                for (i = 0; i < iqs62x_keys->keycodemax; i++) {
                        if (iqs62x_keys->keycode[i] == KEY_RESERVED)
                                continue;

                        if (iqs62x_events[i].reg == IQS62X_EVENT_PROX)
                                event_mask |= iqs62x->dev_desc->prox_mask;
                        else if (iqs62x_events[i].reg == IQS62X_EVENT_HYST)
                                event_mask |= (iqs62x->dev_desc->hyst_mask |
                                               iqs62x->dev_desc->sar_mask);
                }

                ret = regmap_read(iqs62x->regmap, iqs62x->dev_desc->hall_flags,
                                  &val);
                if (ret)
                        return ret;

                /*
                 * Hall UI flags represent switches and are unmasked if their
                 * corresponding child nodes are present.
                 */
                for (i = 0; i < ARRAY_SIZE(iqs62x_keys->switches); i++) {
                        if (!(iqs62x_keys->switches[i].enabled))
                                continue;

                        flag = iqs62x_keys->switches[i].flag;

                        if (iqs62x_events[flag].reg != IQS62X_EVENT_HALL)
                                continue;

                        event_mask |= iqs62x->dev_desc->hall_mask;

                        input_report_switch(iqs62x_keys->input,
                                            iqs62x_keys->switches[i].code,
                                            (val & iqs62x_events[flag].mask) ==
                                            iqs62x_events[flag].val);
                }

                input_sync(iqs62x_keys->input);
                break;

        case IQS624_PROD_NUM:
                event_reg = IQS624_HALL_UI;

                /*
                 * Interval change events represent keys and are unmasked if
                 * either wheel movement flag is mapped to a valid keycode.
                 */
                if (iqs62x_keys->keycode[IQS62X_EVENT_WHEEL_UP] != KEY_RESERVED)
                        event_mask |= IQS624_HALL_UI_INT_EVENT;

                if (iqs62x_keys->keycode[IQS62X_EVENT_WHEEL_DN] != KEY_RESERVED)
                        event_mask |= IQS624_HALL_UI_INT_EVENT;

                ret = regmap_read(iqs62x->regmap, iqs62x->dev_desc->interval,
                                  &val);
                if (ret)
                        return ret;

                iqs62x_keys->interval = val;
                break;

        default:
                return 0;
        }

        return regmap_update_bits(iqs62x->regmap, event_reg, event_mask, 0);
}

static int iqs62x_keys_notifier(struct notifier_block *notifier,
                                unsigned long event_flags, void *context)
{
        struct iqs62x_event_data *event_data = context;
        struct iqs62x_keys_private *iqs62x_keys;
        int ret, i;

        iqs62x_keys = container_of(notifier, struct iqs62x_keys_private,
                                   notifier);

        if (event_flags & BIT(IQS62X_EVENT_SYS_RESET)) {
                ret = iqs62x_keys_init(iqs62x_keys);
                if (ret) {
                        dev_err(iqs62x_keys->input->dev.parent,
                                "Failed to re-initialize device: %d\n", ret);
                        return NOTIFY_BAD;
                }

                return NOTIFY_OK;
        }

        for (i = 0; i < iqs62x_keys->keycodemax; i++) {
                if (iqs62x_events[i].reg == IQS62X_EVENT_WHEEL &&
                    event_data->interval == iqs62x_keys->interval)
                        continue;

                input_report_key(iqs62x_keys->input, iqs62x_keys->keycode[i],
                                 event_flags & BIT(i));
        }

        for (i = 0; i < ARRAY_SIZE(iqs62x_keys->switches); i++)
                if (iqs62x_keys->switches[i].enabled)
                        input_report_switch(iqs62x_keys->input,
                                            iqs62x_keys->switches[i].code,
                                            event_flags &
                                            BIT(iqs62x_keys->switches[i].flag));

        input_sync(iqs62x_keys->input);

        if (event_data->interval == iqs62x_keys->interval)
                return NOTIFY_OK;

        /*
         * Each frame contains at most one wheel event (up or down), in which
         * case a complementary release cycle is emulated.
         */
        if (event_flags & BIT(IQS62X_EVENT_WHEEL_UP)) {
                input_report_key(iqs62x_keys->input,
                                 iqs62x_keys->keycode[IQS62X_EVENT_WHEEL_UP],
                                 0);
                input_sync(iqs62x_keys->input);
        } else if (event_flags & BIT(IQS62X_EVENT_WHEEL_DN)) {
                input_report_key(iqs62x_keys->input,
                                 iqs62x_keys->keycode[IQS62X_EVENT_WHEEL_DN],
                                 0);
                input_sync(iqs62x_keys->input);
        }

        iqs62x_keys->interval = event_data->interval;

        return NOTIFY_OK;
}

static int iqs62x_keys_probe(struct platform_device *pdev)
{
        struct iqs62x_core *iqs62x = dev_get_drvdata(pdev->dev.parent);
        struct iqs62x_keys_private *iqs62x_keys;
        struct input_dev *input;
        int ret, i;

        iqs62x_keys = devm_kzalloc(&pdev->dev, sizeof(*iqs62x_keys),
                                   GFP_KERNEL);
        if (!iqs62x_keys)
                return -ENOMEM;

        platform_set_drvdata(pdev, iqs62x_keys);

        ret = iqs62x_keys_parse_prop(pdev, iqs62x_keys);
        if (ret)
                return ret;

        input = devm_input_allocate_device(&pdev->dev);
        if (!input)
                return -ENOMEM;

        input->keycodemax = iqs62x_keys->keycodemax;
        input->keycode = iqs62x_keys->keycode;
        input->keycodesize = sizeof(*iqs62x_keys->keycode);

        input->name = iqs62x->dev_desc->dev_name;
        input->id.bustype = BUS_I2C;

        for (i = 0; i < iqs62x_keys->keycodemax; i++)
                if (iqs62x_keys->keycode[i] != KEY_RESERVED)
                        input_set_capability(input, EV_KEY,
                                             iqs62x_keys->keycode[i]);

        for (i = 0; i < ARRAY_SIZE(iqs62x_keys->switches); i++)
                if (iqs62x_keys->switches[i].enabled)
                        input_set_capability(input, EV_SW,
                                             iqs62x_keys->switches[i].code);

        iqs62x_keys->iqs62x = iqs62x;
        iqs62x_keys->input = input;

        ret = iqs62x_keys_init(iqs62x_keys);
        if (ret) {
                dev_err(&pdev->dev, "Failed to initialize device: %d\n", ret);
                return ret;
        }

        ret = input_register_device(iqs62x_keys->input);
        if (ret) {
                dev_err(&pdev->dev, "Failed to register device: %d\n", ret);
                return ret;
        }

        iqs62x_keys->notifier.notifier_call = iqs62x_keys_notifier;
        ret = blocking_notifier_chain_register(&iqs62x_keys->iqs62x->nh,
                                               &iqs62x_keys->notifier);
        if (ret)
                dev_err(&pdev->dev, "Failed to register notifier: %d\n", ret);

        return ret;
}

static void iqs62x_keys_remove(struct platform_device *pdev)
{
        struct iqs62x_keys_private *iqs62x_keys = platform_get_drvdata(pdev);
        int ret;

        ret = blocking_notifier_chain_unregister(&iqs62x_keys->iqs62x->nh,
                                                 &iqs62x_keys->notifier);
        if (ret)
                dev_err(&pdev->dev, "Failed to unregister notifier: %d\n", ret);
}

static struct platform_driver iqs62x_keys_platform_driver = {
        .driver = {
                .name = "iqs62x-keys",
        },
        .probe = iqs62x_keys_probe,
        .remove = iqs62x_keys_remove,
};
module_platform_driver(iqs62x_keys_platform_driver);

MODULE_AUTHOR("Jeff LaBundy <jeff@labundy.com>");
MODULE_DESCRIPTION("Azoteq IQS620A/621/622/624/625 Keys and Switches");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:iqs62x-keys");