// SPDX-License-Identifier: GPL-2.0-only
/*
 * power/home/volume button support for
 * Microsoft Surface Pro 3/4 tablet.
 *
 * Copyright (c) 2015 Intel Corporation.
 * All rights reserved.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/input.h>
#include <linux/acpi.h>
#include <acpi/button.h>

#define SURFACE_PRO3_BUTTON_HID         "MSHW0028"
#define SURFACE_PRO4_BUTTON_HID         "MSHW0040"
#define SURFACE_BUTTON_OBJ_NAME         "VGBI"
#define SURFACE_BUTTON_DEVICE_NAME      "Surface Pro 3/4 Buttons"

#define MSHW0040_DSM_REVISION           0x01
#define MSHW0040_DSM_GET_OMPR           0x02    // get OEM Platform Revision
static const guid_t MSHW0040_DSM_UUID =
        GUID_INIT(0x6fd05c69, 0xcde3, 0x49f4, 0x95, 0xed, 0xab, 0x16, 0x65,
                  0x49, 0x80, 0x35);

#define SURFACE_BUTTON_NOTIFY_TABLET_MODE       0xc8

#define SURFACE_BUTTON_NOTIFY_PRESS_POWER       0xc6
#define SURFACE_BUTTON_NOTIFY_RELEASE_POWER     0xc7

#define SURFACE_BUTTON_NOTIFY_PRESS_HOME        0xc4
#define SURFACE_BUTTON_NOTIFY_RELEASE_HOME      0xc5

#define SURFACE_BUTTON_NOTIFY_PRESS_VOLUME_UP   0xc0
#define SURFACE_BUTTON_NOTIFY_RELEASE_VOLUME_UP 0xc1

#define SURFACE_BUTTON_NOTIFY_PRESS_VOLUME_DOWN         0xc2
#define SURFACE_BUTTON_NOTIFY_RELEASE_VOLUME_DOWN       0xc3

MODULE_AUTHOR("Chen Yu");
MODULE_DESCRIPTION("Surface Pro3 Button Driver");
MODULE_LICENSE("GPL v2");

/*
 * Power button, Home button, Volume buttons support is supposed to
 * be covered by drivers/input/misc/soc_button_array.c, which is implemented
 * according to "Windows ACPI Design Guide for SoC Platforms".
 * However surface pro3 seems not to obey the specs, instead it uses
 * device VGBI(MSHW0028) for dispatching the events.
 * We choose acpi_driver rather than platform_driver/i2c_driver because
 * although VGBI has an i2c resource connected to i2c controller, it
 * is not embedded in any i2c controller's scope, thus neither platform_device
 * will be created, nor i2c_client will be enumerated, we have to use
 * acpi_driver.
 */
static const struct acpi_device_id surface_button_device_ids[] = {
        {SURFACE_PRO3_BUTTON_HID,    0},
        {SURFACE_PRO4_BUTTON_HID,    0},
        {"", 0},
};
MODULE_DEVICE_TABLE(acpi, surface_button_device_ids);

struct surface_button {
        unsigned int type;
        struct input_dev *input;
        char phys[32];                  /* for input device */
        unsigned long pushed;
        bool suspended;
};

static void surface_button_notify(struct acpi_device *device, u32 event)
{
        struct surface_button *button = acpi_driver_data(device);
        struct input_dev *input;
        int key_code = KEY_RESERVED;
        bool pressed = false;

        switch (event) {
        /* Power button press,release handle */
        case SURFACE_BUTTON_NOTIFY_PRESS_POWER:
                pressed = true;
                fallthrough;
        case SURFACE_BUTTON_NOTIFY_RELEASE_POWER:
                key_code = KEY_POWER;
                break;
        /* Home button press,release handle */
        case SURFACE_BUTTON_NOTIFY_PRESS_HOME:
                pressed = true;
                fallthrough;
        case SURFACE_BUTTON_NOTIFY_RELEASE_HOME:
                key_code = KEY_LEFTMETA;
                break;
        /* Volume up button press,release handle */
        case SURFACE_BUTTON_NOTIFY_PRESS_VOLUME_UP:
                pressed = true;
                fallthrough;
        case SURFACE_BUTTON_NOTIFY_RELEASE_VOLUME_UP:
                key_code = KEY_VOLUMEUP;
                break;
        /* Volume down button press,release handle */
        case SURFACE_BUTTON_NOTIFY_PRESS_VOLUME_DOWN:
                pressed = true;
                fallthrough;
        case SURFACE_BUTTON_NOTIFY_RELEASE_VOLUME_DOWN:
                key_code = KEY_VOLUMEDOWN;
                break;
        case SURFACE_BUTTON_NOTIFY_TABLET_MODE:
                dev_warn_once(&device->dev, "Tablet mode is not supported\n");
                break;
        default:
                dev_info_ratelimited(&device->dev,
                                     "Unsupported event [0x%x]\n", event);
                break;
        }
        input = button->input;
        if (key_code == KEY_RESERVED)
                return;
        if (pressed)
                pm_wakeup_dev_event(&device->dev, 0, button->suspended);
        if (button->suspended)
                return;
        input_report_key(input, key_code, pressed?1:0);
        input_sync(input);
}

#ifdef CONFIG_PM_SLEEP
static int surface_button_suspend(struct device *dev)
{
        struct acpi_device *device = to_acpi_device(dev);
        struct surface_button *button = acpi_driver_data(device);

        button->suspended = true;
        return 0;
}

static int surface_button_resume(struct device *dev)
{
        struct acpi_device *device = to_acpi_device(dev);
        struct surface_button *button = acpi_driver_data(device);

        button->suspended = false;
        return 0;
}
#endif

/*
 * Surface Pro 4 and Surface Book 2 / Surface Pro 2017 use the same device
 * ID (MSHW0040) for the power/volume buttons. Make sure this is the right
 * device by checking for the _DSM method and OEM Platform Revision.
 *
 * Returns true if the driver should bind to this device, i.e. the device is
 * either MSWH0028 (Pro 3) or MSHW0040 on a Pro 4 or Book 1.
 */
static bool surface_button_check_MSHW0040(struct acpi_device *dev)
{
        acpi_handle handle = dev->handle;
        union acpi_object *result;
        u64 oem_platform_rev = 0;       // valid revisions are nonzero

        // get OEM platform revision
        result = acpi_evaluate_dsm_typed(handle, &MSHW0040_DSM_UUID,
                                         MSHW0040_DSM_REVISION,
                                         MSHW0040_DSM_GET_OMPR,
                                         NULL, ACPI_TYPE_INTEGER);

        /*
         * If evaluating the _DSM fails, the method is not present. This means
         * that we have either MSHW0028 or MSHW0040 on Pro 4 or Book 1, so we
         * should use this driver. We use revision 0 indicating it is
         * unavailable.
         */

        if (result) {
                oem_platform_rev = result->integer.value;
                ACPI_FREE(result);
        }

        dev_dbg(&dev->dev, "OEM Platform Revision %llu\n", oem_platform_rev);

        return oem_platform_rev == 0;
}


static int surface_button_add(struct acpi_device *device)
{
        struct surface_button *button;
        struct input_dev *input;
        const char *hid = acpi_device_hid(device);
        int error;

        if (strncmp(acpi_device_bid(device), SURFACE_BUTTON_OBJ_NAME,
            strlen(SURFACE_BUTTON_OBJ_NAME)))
                return -ENODEV;

        if (!surface_button_check_MSHW0040(device))
                return -ENODEV;

        button = kzalloc_obj(struct surface_button);
        if (!button)
                return -ENOMEM;

        device->driver_data = button;
        button->input = input = input_allocate_device();
        if (!input) {
                error = -ENOMEM;
                goto err_free_button;
        }

        strscpy(acpi_device_name(device), SURFACE_BUTTON_DEVICE_NAME);
        snprintf(button->phys, sizeof(button->phys), "%s/buttons", hid);

        input->name = acpi_device_name(device);
        input->phys = button->phys;
        input->id.bustype = BUS_HOST;
        input->dev.parent = &device->dev;
        input_set_capability(input, EV_KEY, KEY_POWER);
        input_set_capability(input, EV_KEY, KEY_LEFTMETA);
        input_set_capability(input, EV_KEY, KEY_VOLUMEUP);
        input_set_capability(input, EV_KEY, KEY_VOLUMEDOWN);

        error = input_register_device(input);
        if (error)
                goto err_free_input;

        device_init_wakeup(&device->dev, true);
        dev_info(&device->dev, "%s [%s]\n", acpi_device_name(device),
                 acpi_device_bid(device));
        return 0;

 err_free_input:
        input_free_device(input);
 err_free_button:
        kfree(button);
        return error;
}

static void surface_button_remove(struct acpi_device *device)
{
        struct surface_button *button = acpi_driver_data(device);

        input_unregister_device(button->input);
        kfree(button);
}

static SIMPLE_DEV_PM_OPS(surface_button_pm,
                surface_button_suspend, surface_button_resume);

static struct acpi_driver surface_button_driver = {
        .name = "surface_pro3_button",
        .class = "SurfacePro3",
        .ids = surface_button_device_ids,
        .ops = {
                .add = surface_button_add,
                .remove = surface_button_remove,
                .notify = surface_button_notify,
        },
        .drv.pm = &surface_button_pm,
};

module_acpi_driver(surface_button_driver);