/*
 *  Intel HID event & 5 button array driver
 *
 *  Copyright (C) 2015 Alex Hung <alex.hung@canonical.com>
 *  Copyright (C) 2015 Andrew Lutomirski <luto@kernel.org>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/input.h>
#include <linux/platform_device.h>
#include <linux/input/sparse-keymap.h>
#include <linux/acpi.h>
#include <linux/suspend.h>
#include <acpi/acpi_bus.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Alex Hung");

static const struct acpi_device_id intel_hid_ids[] = {
        {"INT33D5", 0},
        {"", 0},
};

/* In theory, these are HID usages. */
static const struct key_entry intel_hid_keymap[] = {
        /* 1: LSuper (Page 0x07, usage 0xE3) -- unclear what to do */
        /* 2: Toggle SW_ROTATE_LOCK -- easy to implement if seen in wild */
        { KE_KEY, 3, { KEY_NUMLOCK } },
        { KE_KEY, 4, { KEY_HOME } },
        { KE_KEY, 5, { KEY_END } },
        { KE_KEY, 6, { KEY_PAGEUP } },
        { KE_KEY, 7, { KEY_PAGEDOWN } },
        { KE_KEY, 8, { KEY_RFKILL } },
        { KE_KEY, 9, { KEY_POWER } },
        { KE_KEY, 11, { KEY_SLEEP } },
        /* 13 has two different meanings in the spec -- ignore it. */
        { KE_KEY, 14, { KEY_STOPCD } },
        { KE_KEY, 15, { KEY_PLAYPAUSE } },
        { KE_KEY, 16, { KEY_MUTE } },
        { KE_KEY, 17, { KEY_VOLUMEUP } },
        { KE_KEY, 18, { KEY_VOLUMEDOWN } },
        { KE_KEY, 19, { KEY_BRIGHTNESSUP } },
        { KE_KEY, 20, { KEY_BRIGHTNESSDOWN } },
        /* 27: wake -- needs special handling */
        { KE_END },
};

/* 5 button array notification value. */
static const struct key_entry intel_array_keymap[] = {
        { KE_KEY,    0xC2, { KEY_LEFTMETA } },                /* Press */
        { KE_IGNORE, 0xC3, { KEY_LEFTMETA } },                /* Release */
        { KE_KEY,    0xC4, { KEY_VOLUMEUP } },                /* Press */
        { KE_IGNORE, 0xC5, { KEY_VOLUMEUP } },                /* Release */
        { KE_KEY,    0xC6, { KEY_VOLUMEDOWN } },              /* Press */
        { KE_IGNORE, 0xC7, { KEY_VOLUMEDOWN } },              /* Release */
        { KE_SW,     0xC8, { .sw = { SW_ROTATE_LOCK, 1 } } }, /* Press */
        { KE_SW,     0xC9, { .sw = { SW_ROTATE_LOCK, 0 } } }, /* Release */
        { KE_KEY,    0xCE, { KEY_POWER } },                   /* Press */
        { KE_IGNORE, 0xCF, { KEY_POWER } },                   /* Release */
        { KE_END },
};

struct intel_hid_priv {
        struct input_dev *input_dev;
        struct input_dev *array;
        bool wakeup_mode;
};

static int intel_hid_set_enable(struct device *device, bool enable)
{
        acpi_status status;

        status = acpi_execute_simple_method(ACPI_HANDLE(device), "HDSM",
                                            enable);
        if (ACPI_FAILURE(status)) {
                dev_warn(device, "failed to %sable hotkeys\n",
                         enable ? "en" : "dis");
                return -EIO;
        }

        return 0;
}

static void intel_button_array_enable(struct device *device, bool enable)
{
        struct intel_hid_priv *priv = dev_get_drvdata(device);
        acpi_handle handle = ACPI_HANDLE(device);
        unsigned long long button_cap;
        acpi_status status;

        if (!priv->array)
                return;

        /* Query supported platform features */
        status = acpi_evaluate_integer(handle, "BTNC", NULL, &button_cap);
        if (ACPI_FAILURE(status)) {
                dev_warn(device, "failed to get button capability\n");
                return;
        }

        /* Enable|disable features - power button is always enabled */
        status = acpi_execute_simple_method(handle, "BTNE",
                                            enable ? button_cap : 1);
        if (ACPI_FAILURE(status))
                dev_warn(device, "failed to set button capability\n");
}

static int intel_hid_pm_prepare(struct device *device)
{
        struct intel_hid_priv *priv = dev_get_drvdata(device);

        priv->wakeup_mode = true;
        return 0;
}

static int intel_hid_pl_suspend_handler(struct device *device)
{
        if (pm_suspend_via_firmware()) {
                intel_hid_set_enable(device, false);
                intel_button_array_enable(device, false);
        }
        return 0;
}

static int intel_hid_pl_resume_handler(struct device *device)
{
        struct intel_hid_priv *priv = dev_get_drvdata(device);

        priv->wakeup_mode = false;
        if (pm_resume_via_firmware()) {
                intel_hid_set_enable(device, true);
                intel_button_array_enable(device, true);
        }
        return 0;
}

static const struct dev_pm_ops intel_hid_pl_pm_ops = {
        .prepare = intel_hid_pm_prepare,
        .freeze  = intel_hid_pl_suspend_handler,
        .thaw  = intel_hid_pl_resume_handler,
        .restore  = intel_hid_pl_resume_handler,
        .suspend  = intel_hid_pl_suspend_handler,
        .resume  = intel_hid_pl_resume_handler,
};

static int intel_hid_input_setup(struct platform_device *device)
{
        struct intel_hid_priv *priv = dev_get_drvdata(&device->dev);
        int ret;

        priv->input_dev = devm_input_allocate_device(&device->dev);
        if (!priv->input_dev)
                return -ENOMEM;

        ret = sparse_keymap_setup(priv->input_dev, intel_hid_keymap, NULL);
        if (ret)
                return ret;

        priv->input_dev->name = "Intel HID events";
        priv->input_dev->id.bustype = BUS_HOST;

        return input_register_device(priv->input_dev);
}

static int intel_button_array_input_setup(struct platform_device *device)
{
        struct intel_hid_priv *priv = dev_get_drvdata(&device->dev);
        int ret;

        /* Setup input device for 5 button array */
        priv->array = devm_input_allocate_device(&device->dev);
        if (!priv->array)
                return -ENOMEM;

        ret = sparse_keymap_setup(priv->array, intel_array_keymap, NULL);
        if (ret)
                return ret;

        priv->array->name = "Intel HID 5 button array";
        priv->array->id.bustype = BUS_HOST;

        return input_register_device(priv->array);
}

static void notify_handler(acpi_handle handle, u32 event, void *context)
{
        struct platform_device *device = context;
        struct intel_hid_priv *priv = dev_get_drvdata(&device->dev);
        unsigned long long ev_index;
        acpi_status status;

        if (priv->wakeup_mode) {
                /* Wake up on 5-button array events only. */
                if (event == 0xc0 || !priv->array)
                        return;

                if (sparse_keymap_entry_from_scancode(priv->array, event))
                        pm_wakeup_hard_event(&device->dev);
                else
                        dev_info(&device->dev, "unknown event 0x%x\n", event);

                return;
        }

        /* 0xC0 is for HID events, other values are for 5 button array */
        if (event != 0xc0) {
                if (!priv->array ||
                    !sparse_keymap_report_event(priv->array, event, 1, true))
                        dev_info(&device->dev, "unknown event 0x%x\n", event);
                return;
        }

        status = acpi_evaluate_integer(handle, "HDEM", NULL, &ev_index);
        if (ACPI_FAILURE(status)) {
                dev_warn(&device->dev, "failed to get event index\n");
                return;
        }

        if (!sparse_keymap_report_event(priv->input_dev, ev_index, 1, true))
                dev_info(&device->dev, "unknown event index 0x%llx\n",
                         ev_index);
}

static int intel_hid_probe(struct platform_device *device)
{
        acpi_handle handle = ACPI_HANDLE(&device->dev);
        unsigned long long event_cap, mode;
        struct intel_hid_priv *priv;
        acpi_status status;
        int err;

        status = acpi_evaluate_integer(handle, "HDMM", NULL, &mode);
        if (ACPI_FAILURE(status)) {
                dev_warn(&device->dev, "failed to read mode\n");
                return -ENODEV;
        }

        if (mode != 0) {
                /*
                 * This driver only implements "simple" mode.  There appear
                 * to be no other modes, but we should be paranoid and check
                 * for compatibility.
                 */
                dev_info(&device->dev, "platform is not in simple mode\n");
                return -ENODEV;
        }

        priv = devm_kzalloc(&device->dev, sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;
        dev_set_drvdata(&device->dev, priv);

        err = intel_hid_input_setup(device);
        if (err) {
                pr_err("Failed to setup Intel HID hotkeys\n");
                return err;
        }

        /* Setup 5 button array */
        status = acpi_evaluate_integer(handle, "HEBC", NULL, &event_cap);
        if (ACPI_SUCCESS(status) && (event_cap & 0x20000)) {
                dev_info(&device->dev, "platform supports 5 button array\n");
                err = intel_button_array_input_setup(device);
                if (err)
                        pr_err("Failed to setup Intel 5 button array hotkeys\n");
        }

        status = acpi_install_notify_handler(handle,
                                             ACPI_DEVICE_NOTIFY,
                                             notify_handler,
                                             device);
        if (ACPI_FAILURE(status))
                return -EBUSY;

        err = intel_hid_set_enable(&device->dev, true);
        if (err)
                goto err_remove_notify;

        if (priv->array) {
                intel_button_array_enable(&device->dev, true);

                /* Call button load method to enable HID power button */
                status = acpi_evaluate_object(handle, "BTNL", NULL, NULL);
                if (ACPI_FAILURE(status))
                        dev_warn(&device->dev,
                                 "failed to enable HID power button\n");
        }

        device_init_wakeup(&device->dev, true);
        return 0;

err_remove_notify:
        acpi_remove_notify_handler(handle, ACPI_DEVICE_NOTIFY, notify_handler);

        return err;
}

static int intel_hid_remove(struct platform_device *device)
{
        acpi_handle handle = ACPI_HANDLE(&device->dev);

        acpi_remove_notify_handler(handle, ACPI_DEVICE_NOTIFY, notify_handler);
        intel_hid_set_enable(&device->dev, false);
        intel_button_array_enable(&device->dev, false);

        /*
         * Even if we failed to shut off the event stream, we can still
         * safely detach from the device.
         */
        return 0;
}

static struct platform_driver intel_hid_pl_driver = {
        .driver = {
                .name = "intel-hid",
                .acpi_match_table = intel_hid_ids,
                .pm = &intel_hid_pl_pm_ops,
        },
        .probe = intel_hid_probe,
        .remove = intel_hid_remove,
};
MODULE_DEVICE_TABLE(acpi, intel_hid_ids);

/*
 * Unfortunately, some laptops provide a _HID="INT33D5" device with
 * _CID="PNP0C02".  This causes the pnpacpi scan driver to claim the
 * ACPI node, so no platform device will be created.  The pnpacpi
 * driver rejects this device in subsequent processing, so no physical
 * node is created at all.
 *
 * As a workaround until the ACPI core figures out how to handle
 * this corner case, manually ask the ACPI platform device code to
 * claim the ACPI node.
 */
static acpi_status __init
check_acpi_dev(acpi_handle handle, u32 lvl, void *context, void **rv)
{
        const struct acpi_device_id *ids = context;
        struct acpi_device *dev;

        if (acpi_bus_get_device(handle, &dev) != 0)
                return AE_OK;

        if (acpi_match_device_ids(dev, ids) == 0)
                if (acpi_create_platform_device(dev, NULL))
                        dev_info(&dev->dev,
                                 "intel-hid: created platform device\n");

        return AE_OK;
}

static int __init intel_hid_init(void)
{
        acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
                            ACPI_UINT32_MAX, check_acpi_dev, NULL,
                            (void *)intel_hid_ids, NULL);

        return platform_driver_register(&intel_hid_pl_driver);
}
module_init(intel_hid_init);

static void __exit intel_hid_exit(void)
{
        platform_driver_unregister(&intel_hid_pl_driver);
}
module_exit(intel_hid_exit);