/*
 *  quickstart.c - ACPI Direct App Launch driver
 *
 *
 *  Copyright (C) 2007-2010 Angelo Arrifano <miknix@gmail.com>
 *
 *  Information gathered from disassembled dsdt and from here:
 *  <http://www.microsoft.com/whdc/system/platform/firmware/DirAppLaunch.mspx>
 *
 *  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.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */

#define QUICKSTART_VERSION "1.04"

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/types.h>
#include <acpi/acpi_drivers.h>
#include <linux/platform_device.h>
#include <linux/input.h>

MODULE_AUTHOR("Angelo Arrifano");
MODULE_DESCRIPTION("ACPI Direct App Launch driver");
MODULE_LICENSE("GPL");

#define QUICKSTART_ACPI_DEVICE_NAME     "quickstart"
#define QUICKSTART_ACPI_CLASS           "quickstart"
#define QUICKSTART_ACPI_HID             "PNP0C32"

#define QUICKSTART_PF_DRIVER_NAME       "quickstart"
#define QUICKSTART_PF_DEVICE_NAME       "quickstart"

/*
 * There will be two events:
 * 0x02 - A hot button was pressed while device was off/sleeping.
 * 0x80 - A hot button was pressed while device was up.
 */
#define QUICKSTART_EVENT_WAKE           0x02
#define QUICKSTART_EVENT_RUNTIME        0x80

struct quickstart_button {
        char *name;
        unsigned int id;
        struct list_head list;
};

struct quickstart_acpi {
        struct acpi_device *device;
        struct quickstart_button *button;
};

static LIST_HEAD(buttons);
static struct quickstart_button *pressed;

static struct input_dev *quickstart_input;

/* Platform driver functions */
static ssize_t quickstart_buttons_show(struct device *dev,
                                        struct device_attribute *attr,
                                        char *buf)
{
        int count = 0;
        struct quickstart_button *b;

        if (list_empty(&buttons))
                return snprintf(buf, PAGE_SIZE, "none");

        list_for_each_entry(b, &buttons, list) {
                count += snprintf(buf + count, PAGE_SIZE - count, "%u\t%s\n",
                                                        b->id, b->name);

                if (count >= PAGE_SIZE) {
                        count = PAGE_SIZE;
                        break;
                }
        }

        return count;
}

static ssize_t quickstart_pressed_button_show(struct device *dev,
                                                struct device_attribute *attr,
                                                char *buf)
{
        return scnprintf(buf, PAGE_SIZE, "%s\n",
                                        (pressed ? pressed->name : "none"));
}


static ssize_t quickstart_pressed_button_store(struct device *dev,
                                                struct device_attribute *attr,
                                                const char *buf, size_t count)
{
        if (count < 2)
                return -EINVAL;

        if (strncasecmp(buf, "none", 4) != 0)
                return -EINVAL;

        pressed = NULL;
        return count;
}

/* Helper functions */
static struct quickstart_button *quickstart_buttons_add(void)
{
        struct quickstart_button *b;

        b = kzalloc(sizeof(*b), GFP_KERNEL);
        if (!b)
                return NULL;

        list_add_tail(&b->list, &buttons);

        return b;
}

static void quickstart_button_del(struct quickstart_button *data)
{
        if (!data)
                return;

        list_del(&data->list);
        kfree(data->name);
        kfree(data);
}

static void quickstart_buttons_free(void)
{
        struct quickstart_button *b, *n;

        list_for_each_entry_safe(b, n, &buttons, list)
                quickstart_button_del(b);
}

/* ACPI Driver functions */
static void quickstart_acpi_notify(acpi_handle handle, u32 event, void *data)
{
        struct quickstart_acpi *quickstart = data;

        if (!quickstart)
                return;

        switch (event) {
        case QUICKSTART_EVENT_WAKE:
                pressed = quickstart->button;
                break;
        case QUICKSTART_EVENT_RUNTIME:
                input_report_key(quickstart_input, quickstart->button->id, 1);
                input_sync(quickstart_input);
                input_report_key(quickstart_input, quickstart->button->id, 0);
                input_sync(quickstart_input);
                break;
        default:
                pr_err("Unexpected ACPI event notify (%u)\n", event);
                break;
        }
}

static int quickstart_acpi_ghid(struct quickstart_acpi *quickstart)
{
        acpi_status status;
        struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
        int ret = 0;

        /*
         * This returns a buffer telling the button usage ID,
         * and triggers pending notify events (The ones before booting).
         */
        status = acpi_evaluate_object(quickstart->device->handle, "GHID", NULL,
                                                                &buffer);
        if (ACPI_FAILURE(status)) {
                pr_err("%s GHID method failed\n", quickstart->button->name);
                return -EINVAL;
        }

        /*
         * <<The GHID method can return a BYTE, WORD, or DWORD.
         * The value must be encoded in little-endian byte
         * order (least significant byte first).>>
         */
        switch (buffer.length) {
        case 1:
                quickstart->button->id = *(uint8_t *)buffer.pointer;
                break;
        case 2:
                quickstart->button->id = *(uint16_t *)buffer.pointer;
                break;
        case 4:
                quickstart->button->id = *(uint32_t *)buffer.pointer;
                break;
        case 8:
                quickstart->button->id = *(uint64_t *)buffer.pointer;
                break;
        default:
                pr_err("%s GHID method returned buffer of unexpected length %lu\n",
                                quickstart->button->name,
                                (unsigned long)buffer.length);
                ret = -EINVAL;
                break;
        }

        kfree(buffer.pointer);

        return ret;
}

static int quickstart_acpi_config(struct quickstart_acpi *quickstart)
{
        char *bid = acpi_device_bid(quickstart->device);
        char *name;

        name = kmalloc(strlen(bid) + 1, GFP_KERNEL);
        if (!name)
                return -ENOMEM;

        /* Add new button to list */
        quickstart->button = quickstart_buttons_add();
        if (!quickstart->button) {
                kfree(name);
                return -ENOMEM;
        }

        quickstart->button->name = name;
        strcpy(quickstart->button->name, bid);

        return 0;
}

static int quickstart_acpi_add(struct acpi_device *device)
{
        int ret;
        acpi_status status;
        struct quickstart_acpi *quickstart;

        if (!device)
                return -EINVAL;

        quickstart = kzalloc(sizeof(*quickstart), GFP_KERNEL);
        if (!quickstart)
                return -ENOMEM;

        quickstart->device = device;

        strcpy(acpi_device_name(device), QUICKSTART_ACPI_DEVICE_NAME);
        strcpy(acpi_device_class(device), QUICKSTART_ACPI_CLASS);
        device->driver_data = quickstart;

        /* Add button to list and initialize some stuff */
        ret = quickstart_acpi_config(quickstart);
        if (ret < 0)
                goto fail_config;

        status = acpi_install_notify_handler(device->handle, ACPI_ALL_NOTIFY,
                                                quickstart_acpi_notify,
                                                quickstart);
        if (ACPI_FAILURE(status)) {
                pr_err("Notify handler install error\n");
                ret = -ENODEV;
                goto fail_installnotify;
        }

        ret = quickstart_acpi_ghid(quickstart);
        if (ret < 0)
                goto fail_ghid;

        return 0;

fail_ghid:
        acpi_remove_notify_handler(device->handle, ACPI_ALL_NOTIFY,
                                                quickstart_acpi_notify);

fail_installnotify:
        quickstart_button_del(quickstart->button);

fail_config:

        kfree(quickstart);

        return ret;
}

static int quickstart_acpi_remove(struct acpi_device *device)
{
        acpi_status status;
        struct quickstart_acpi *quickstart;

        if (!device)
                return -EINVAL;

        quickstart = acpi_driver_data(device);
        if (!quickstart)
                return -EINVAL;

        status = acpi_remove_notify_handler(device->handle, ACPI_ALL_NOTIFY,
                                                quickstart_acpi_notify);
        if (ACPI_FAILURE(status))
                pr_err("Error removing notify handler\n");

        kfree(quickstart);

        return 0;
}

/* Platform driver structs */
static DEVICE_ATTR(pressed_button, 0666, quickstart_pressed_button_show,
                                         quickstart_pressed_button_store);
static DEVICE_ATTR(buttons, 0444, quickstart_buttons_show, NULL);
static struct platform_device *pf_device;
static struct platform_driver pf_driver = {
        .driver = {
                .name = QUICKSTART_PF_DRIVER_NAME,
                .owner = THIS_MODULE,
        }
};

static const struct acpi_device_id quickstart_device_ids[] = {
        {QUICKSTART_ACPI_HID, 0},
        {"", 0},
};

static struct acpi_driver quickstart_acpi_driver = {
        .name = "quickstart",
        .class = QUICKSTART_ACPI_CLASS,
        .ids = quickstart_device_ids,
        .ops = {
                        .add = quickstart_acpi_add,
                        .remove = quickstart_acpi_remove,
                },
};

/* Module functions */
static void quickstart_exit(void)
{
        input_unregister_device(quickstart_input);

        device_remove_file(&pf_device->dev, &dev_attr_pressed_button);
        device_remove_file(&pf_device->dev, &dev_attr_buttons);

        platform_device_unregister(pf_device);

        platform_driver_unregister(&pf_driver);

        acpi_bus_unregister_driver(&quickstart_acpi_driver);

        quickstart_buttons_free();
}

static int __init quickstart_init_input(void)
{
        struct quickstart_button *b;
        int ret;

        quickstart_input = input_allocate_device();

        if (!quickstart_input)
                return -ENOMEM;

        quickstart_input->name = "Quickstart ACPI Buttons";
        quickstart_input->id.bustype = BUS_HOST;

        list_for_each_entry(b, &buttons, list) {
                set_bit(EV_KEY, quickstart_input->evbit);
                set_bit(b->id, quickstart_input->keybit);
        }

        ret = input_register_device(quickstart_input);
        if (ret) {
                input_free_device(quickstart_input);
                return ret;
        }

        return 0;
}

static int __init quickstart_init(void)
{
        int ret;

        /* ACPI Check */
        if (acpi_disabled)
                return -ENODEV;

        /* ACPI driver register */
        ret = acpi_bus_register_driver(&quickstart_acpi_driver);
        if (ret)
                return ret;

        /* If existing bus with no devices */
        if (list_empty(&buttons)) {
                ret = -ENODEV;
                goto fail_pfdrv_reg;
        }

        /* Platform driver register */
        ret = platform_driver_register(&pf_driver);
        if (ret)
                goto fail_pfdrv_reg;

        /* Platform device register */
        pf_device = platform_device_alloc(QUICKSTART_PF_DEVICE_NAME, -1);
        if (!pf_device) {
                ret = -ENOMEM;
                goto fail_pfdev_alloc;
        }
        ret = platform_device_add(pf_device);
        if (ret)
                goto fail_pfdev_add;

        /* Create device sysfs file */
        ret = device_create_file(&pf_device->dev, &dev_attr_pressed_button);
        if (ret)
                goto fail_dev_file;

        ret = device_create_file(&pf_device->dev, &dev_attr_buttons);
        if (ret)
                goto fail_dev_file2;

        /* Input device */
        ret = quickstart_init_input();
        if (ret)
                goto fail_input;

        pr_info("ACPI Direct App Launch ver %s\n", QUICKSTART_VERSION);

        return 0;
fail_input:
        device_remove_file(&pf_device->dev, &dev_attr_buttons);

fail_dev_file2:
        device_remove_file(&pf_device->dev, &dev_attr_pressed_button);

fail_dev_file:
        platform_device_del(pf_device);

fail_pfdev_add:
        platform_device_put(pf_device);

fail_pfdev_alloc:
        platform_driver_unregister(&pf_driver);

fail_pfdrv_reg:
        acpi_bus_unregister_driver(&quickstart_acpi_driver);

        return ret;
}

module_init(quickstart_init);
module_exit(quickstart_exit);