// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Toshiba HDD Active Protection Sensor (HAPS) driver
 *
 * Copyright (C) 2014 Azael Avalos <coproscefalo@gmail.com>
 */

#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>
#include <linux/platform_device.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_debug("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 const struct attribute_group haps_attr_group = {
        .attrs = haps_attributes,
};

/*
 * ACPI stuff
 */
static void toshiba_haps_notify(acpi_handle handle, u32 event, void *data)
{
        struct acpi_device *device = data;

        pr_debug("Received event: 0x%x\n", event);

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

static void toshiba_haps_remove(struct platform_device *pdev)
{
        struct acpi_device *device = ACPI_COMPANION(&pdev->dev);

        acpi_dev_remove_notify_handler(device, ACPI_DEVICE_NOTIFY,
                                       toshiba_haps_notify);

        sysfs_remove_group(&device->dev.kobj, &haps_attr_group);

        if (toshiba_haps)
                toshiba_haps = NULL;

        dev_set_drvdata(&device->dev, NULL);
}

/* 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)) {
                pr_err("ACPI call to query HDD protection failed\n");
                return 0;
        }

        if (!hdd_present) {
                pr_info("HDD protection not available or using SSD\n");
                return 0;
        }

        return 1;
}

static int toshiba_haps_probe(struct platform_device *pdev)
{
        struct toshiba_haps_dev *haps;
        struct acpi_device *acpi_dev;
        int ret;

        if (toshiba_haps)
                return -EBUSY;

        acpi_dev = ACPI_COMPANION(&pdev->dev);
        if (!acpi_dev)
                return -ENODEV;

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

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

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

        haps->acpi_dev = acpi_dev;
        haps->protection_level = 2;

        dev_set_drvdata(&acpi_dev->dev, haps);
        platform_set_drvdata(pdev, 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;

        ret = acpi_dev_install_notify_handler(acpi_dev, ACPI_DEVICE_NOTIFY,
                                              toshiba_haps_notify, acpi_dev);
        if (ret)
                goto err;

        toshiba_haps = haps;

        return 0;

err:
        sysfs_remove_group(&acpi_dev->dev.kobj, &haps_attr_group);
        return ret;
}

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

        /* 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 = dev_get_drvdata(device);
        int ret;

        /* 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 platform_driver toshiba_haps_driver = {
        .probe = toshiba_haps_probe,
        .remove = toshiba_haps_remove,
        .driver = {
                .name = "Toshiba HAPS",
                .acpi_match_table = haps_device_ids,
                .pm = &toshiba_haps_pm,
        },
};

module_platform_driver(toshiba_haps_driver);