/*
 * Toshiba HDD Active Protection Sensor (HAPS) driver
 *
 * Copyright (C) 2014 Azael Avalos <coproscefalo@gmail.com>
 *
 * 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.
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

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

MODULE_AUTHOR("Azael Avalos <coproscefalo@gmail.com>");
MODULE_DESCRIPTION("Toshiba HDD Active Protection Sensor");
MODULE_LICENSE("GPL");

struct toshiba_haps_dev {
        struct acpi_device *acpi_dev;

        int protection_level;
};

static struct toshiba_haps_dev *toshiba_haps;

/* HAPS functions */
static int toshiba_haps_reset_protection(acpi_handle handle)
{
        acpi_status status;

        status = acpi_evaluate_object(handle, "RSSS", NULL, NULL);
        if (ACPI_FAILURE(status)) {
                pr_err("Unable to reset the HDD protection\n");
                return -EIO;
        }

        return 0;
}

static int toshiba_haps_protection_level(acpi_handle handle, int level)
{
        acpi_status status;

        status = acpi_execute_simple_method(handle, "PTLV", level);
        if (ACPI_FAILURE(status)) {
                pr_err("Error while setting the protection level\n");
                return -EIO;
        }

        pr_info("HDD protection level set to: %d\n", level);

        return 0;
}

/* sysfs files */
static ssize_t protection_level_show(struct device *dev,
                                     struct device_attribute *attr, char *buf)
{
        struct toshiba_haps_dev *haps = dev_get_drvdata(dev);

        return sprintf(buf, "%i\n", haps->protection_level);
}

static ssize_t protection_level_store(struct device *dev,
                                      struct device_attribute *attr,
                                      const char *buf, size_t count)
{
        struct toshiba_haps_dev *haps = dev_get_drvdata(dev);
        int level;
        int ret;

        ret = kstrtoint(buf, 0, &level);
        if (ret)
                return ret;
        /*
         * Check for supported levels, which can be:
         * 0 - Disabled | 1 - Low | 2 - Medium | 3 - High
         */
        if (level < 0 || level > 3)
                return -EINVAL;

        /* Set the sensor level */
        ret = toshiba_haps_protection_level(haps->acpi_dev->handle, level);
        if (ret != 0)
                return ret;

        haps->protection_level = level;

        return count;
}
static DEVICE_ATTR_RW(protection_level);

static ssize_t reset_protection_store(struct device *dev,
                                      struct device_attribute *attr,
                                      const char *buf, size_t count)
{
        struct toshiba_haps_dev *haps = dev_get_drvdata(dev);
        int reset;
        int ret;

        ret = kstrtoint(buf, 0, &reset);
        if (ret)
                return ret;
        /* The only accepted value is 1 */
        if (reset != 1)
                return -EINVAL;

        /* Reset the protection interface */
        ret = toshiba_haps_reset_protection(haps->acpi_dev->handle);
        if (ret != 0)
                return ret;

        return count;
}
static DEVICE_ATTR_WO(reset_protection);

static struct attribute *haps_attributes[] = {
        &dev_attr_protection_level.attr,
        &dev_attr_reset_protection.attr,
        NULL,
};

static struct attribute_group haps_attr_group = {
        .attrs = haps_attributes,
};

/*
 * ACPI stuff
 */
static void toshiba_haps_notify(struct acpi_device *device, u32 event)
{
        pr_info("Received event: 0x%x", event);

        acpi_bus_generate_netlink_event(device->pnp.device_class,
                                        dev_name(&device->dev),
                                        event, 0);
}

static int toshiba_haps_remove(struct acpi_device *device)
{
        sysfs_remove_group(&device->dev.kobj, &haps_attr_group);

        if (toshiba_haps)
                toshiba_haps = NULL;

        return 0;
}

/* Helper function */
static int toshiba_haps_available(acpi_handle handle)
{
        acpi_status status;
        u64 hdd_present;

        /*
         * A non existent device as well as having (only)
         * Solid State Drives can cause the call to fail.
         */
        status = acpi_evaluate_integer(handle, "_STA", NULL,
                                       &hdd_present);
        if (ACPI_FAILURE(status) || !hdd_present) {
                pr_info("HDD protection not available or using SSD\n");
                return 0;
        }

        return 1;
}

static int toshiba_haps_add(struct acpi_device *acpi_dev)
{
        struct toshiba_haps_dev *haps;
        int ret;

        if (toshiba_haps)
                return -EBUSY;

        if (!toshiba_haps_available(acpi_dev->handle))
                return -ENODEV;

        pr_info("Toshiba HDD Active Protection Sensor device\n");

        haps = kzalloc(sizeof(struct toshiba_haps_dev), GFP_KERNEL);
        if (!haps)
                return -ENOMEM;

        haps->acpi_dev = acpi_dev;
        haps->protection_level = 2;
        acpi_dev->driver_data = haps;
        dev_set_drvdata(&acpi_dev->dev, haps);

        /* Set the protection level, currently at level 2 (Medium) */
        ret = toshiba_haps_protection_level(acpi_dev->handle, 2);
        if (ret != 0)
                return ret;

        ret = sysfs_create_group(&acpi_dev->dev.kobj, &haps_attr_group);
        if (ret)
                return ret;

        toshiba_haps = haps;

        return 0;
}

#ifdef CONFIG_PM_SLEEP
static int toshiba_haps_suspend(struct device *device)
{
        struct toshiba_haps_dev *haps;
        int ret;

        haps = acpi_driver_data(to_acpi_device(device));

        /* Deactivate the protection on suspend */
        ret = toshiba_haps_protection_level(haps->acpi_dev->handle, 0);

        return ret;
}

static int toshiba_haps_resume(struct device *device)
{
        struct toshiba_haps_dev *haps;
        int ret;

        haps = acpi_driver_data(to_acpi_device(device));

        /* Set the stored protection level */
        ret = toshiba_haps_protection_level(haps->acpi_dev->handle,
                                            haps->protection_level);

        /* Reset the protection on resume */
        ret = toshiba_haps_reset_protection(haps->acpi_dev->handle);
        if (ret != 0)
                return ret;

        return ret;
}
#endif

static SIMPLE_DEV_PM_OPS(toshiba_haps_pm,
                         toshiba_haps_suspend, toshiba_haps_resume);

static const struct acpi_device_id haps_device_ids[] = {
        {"TOS620A", 0},
        {"", 0},
};
MODULE_DEVICE_TABLE(acpi, haps_device_ids);

static struct acpi_driver toshiba_haps_driver = {
        .name = "Toshiba HAPS",
        .owner = THIS_MODULE,
        .ids = haps_device_ids,
        .flags = ACPI_DRIVER_ALL_NOTIFY_EVENTS,
        .ops = {
                .add =          toshiba_haps_add,
                .remove =       toshiba_haps_remove,
                .notify =       toshiba_haps_notify,
        },
        .drv.pm = &toshiba_haps_pm,
};

module_acpi_driver(toshiba_haps_driver);