/*
 * scan.c - support for transforming the ACPI namespace into individual objects
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/acpi.h>
#include <linux/signal.h>
#include <linux/kthread.h>
#include <linux/dmi.h>
#include <linux/nls.h>

#include <asm/pgtable.h>

#include "internal.h"

#define _COMPONENT              ACPI_BUS_COMPONENT
ACPI_MODULE_NAME("scan");
extern struct acpi_device *acpi_root;

#define ACPI_BUS_CLASS                  "system_bus"
#define ACPI_BUS_HID                    "LNXSYBUS"
#define ACPI_BUS_DEVICE_NAME            "System Bus"

#define ACPI_IS_ROOT_DEVICE(device)    (!(device)->parent)

#define INVALID_ACPI_HANDLE     ((acpi_handle)empty_zero_page)

/*
 * If set, devices will be hot-removed even if they cannot be put offline
 * gracefully (from the kernel's standpoint).
 */
bool acpi_force_hot_remove;

static const char *dummy_hid = "device";

static LIST_HEAD(acpi_dep_list);
static DEFINE_MUTEX(acpi_dep_list_lock);
static LIST_HEAD(acpi_bus_id_list);
static DEFINE_MUTEX(acpi_scan_lock);
static LIST_HEAD(acpi_scan_handlers_list);
DEFINE_MUTEX(acpi_device_lock);
LIST_HEAD(acpi_wakeup_device_list);
static DEFINE_MUTEX(acpi_hp_context_lock);

struct acpi_dep_data {
        struct list_head node;
        acpi_handle master;
        acpi_handle slave;
};

struct acpi_device_bus_id{
        char bus_id[15];
        unsigned int instance_no;
        struct list_head node;
};

void acpi_scan_lock_acquire(void)
{
        mutex_lock(&acpi_scan_lock);
}
EXPORT_SYMBOL_GPL(acpi_scan_lock_acquire);

void acpi_scan_lock_release(void)
{
        mutex_unlock(&acpi_scan_lock);
}
EXPORT_SYMBOL_GPL(acpi_scan_lock_release);

void acpi_lock_hp_context(void)
{
        mutex_lock(&acpi_hp_context_lock);
}

void acpi_unlock_hp_context(void)
{
        mutex_unlock(&acpi_hp_context_lock);
}

void acpi_initialize_hp_context(struct acpi_device *adev,
                                struct acpi_hotplug_context *hp,
                                int (*notify)(struct acpi_device *, u32),
                                void (*uevent)(struct acpi_device *, u32))
{
        acpi_lock_hp_context();
        hp->notify = notify;
        hp->uevent = uevent;
        acpi_set_hp_context(adev, hp);
        acpi_unlock_hp_context();
}
EXPORT_SYMBOL_GPL(acpi_initialize_hp_context);

int acpi_scan_add_handler(struct acpi_scan_handler *handler)
{
        if (!handler)
                return -EINVAL;

        list_add_tail(&handler->list_node, &acpi_scan_handlers_list);
        return 0;
}

int acpi_scan_add_handler_with_hotplug(struct acpi_scan_handler *handler,
                                       const char *hotplug_profile_name)
{
        int error;

        error = acpi_scan_add_handler(handler);
        if (error)
                return error;

        acpi_sysfs_add_hotplug_profile(&handler->hotplug, hotplug_profile_name);
        return 0;
}

/**
 * create_pnp_modalias - Create hid/cid(s) string for modalias and uevent
 * @acpi_dev: ACPI device object.
 * @modalias: Buffer to print into.
 * @size: Size of the buffer.
 *
 * Creates hid/cid(s) string needed for modalias and uevent
 * e.g. on a device with hid:IBM0001 and cid:ACPI0001 you get:
 * char *modalias: "acpi:IBM0001:ACPI0001"
 * Return: 0: no _HID and no _CID
 *         -EINVAL: output error
 *         -ENOMEM: output is truncated
*/
static int create_pnp_modalias(struct acpi_device *acpi_dev, char *modalias,
                               int size)
{
        int len;
        int count;
        struct acpi_hardware_id *id;

        /*
         * Since we skip PRP0001 from the modalias below, 0 should be returned
         * if PRP0001 is the only ACPI/PNP ID in the device's list.
         */
        count = 0;
        list_for_each_entry(id, &acpi_dev->pnp.ids, list)
                if (strcmp(id->id, "PRP0001"))
                        count++;

        if (!count)
                return 0;

        len = snprintf(modalias, size, "acpi:");
        if (len <= 0)
                return len;

        size -= len;

        list_for_each_entry(id, &acpi_dev->pnp.ids, list) {
                if (!strcmp(id->id, "PRP0001"))
                        continue;

                count = snprintf(&modalias[len], size, "%s:", id->id);
                if (count < 0)
                        return -EINVAL;

                if (count >= size)
                        return -ENOMEM;

                len += count;
                size -= count;
        }
        modalias[len] = '\0';
        return len;
}

/**
 * create_of_modalias - Creates DT compatible string for modalias and uevent
 * @acpi_dev: ACPI device object.
 * @modalias: Buffer to print into.
 * @size: Size of the buffer.
 *
 * Expose DT compatible modalias as of:NnameTCcompatible.  This function should
 * only be called for devices having PRP0001 in their list of ACPI/PNP IDs.
 */
static int create_of_modalias(struct acpi_device *acpi_dev, char *modalias,
                              int size)
{
        struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER };
        const union acpi_object *of_compatible, *obj;
        int len, count;
        int i, nval;
        char *c;

        acpi_get_name(acpi_dev->handle, ACPI_SINGLE_NAME, &buf);
        /* DT strings are all in lower case */
        for (c = buf.pointer; *c != '\0'; c++)
                *c = tolower(*c);

        len = snprintf(modalias, size, "of:N%sT", (char *)buf.pointer);
        ACPI_FREE(buf.pointer);

        if (len <= 0)
                return len;

        of_compatible = acpi_dev->data.of_compatible;
        if (of_compatible->type == ACPI_TYPE_PACKAGE) {
                nval = of_compatible->package.count;
                obj = of_compatible->package.elements;
        } else { /* Must be ACPI_TYPE_STRING. */
                nval = 1;
                obj = of_compatible;
        }
        for (i = 0; i < nval; i++, obj++) {
                count = snprintf(&modalias[len], size, "C%s",
                                 obj->string.pointer);
                if (count < 0)
                        return -EINVAL;

                if (count >= size)
                        return -ENOMEM;

                len += count;
                size -= count;
        }
        modalias[len] = '\0';
        return len;
}

/*
 * acpi_companion_match() - Can we match via ACPI companion device
 * @dev: Device in question
 *
 * Check if the given device has an ACPI companion and if that companion has
 * a valid list of PNP IDs, and if the device is the first (primary) physical
 * device associated with it.  Return the companion pointer if that's the case
 * or NULL otherwise.
 *
 * If multiple physical devices are attached to a single ACPI companion, we need
 * to be careful.  The usage scenario for this kind of relationship is that all
 * of the physical devices in question use resources provided by the ACPI
 * companion.  A typical case is an MFD device where all the sub-devices share
 * the parent's ACPI companion.  In such cases we can only allow the primary
 * (first) physical device to be matched with the help of the companion's PNP
 * IDs.
 *
 * Additional physical devices sharing the ACPI companion can still use
 * resources available from it but they will be matched normally using functions
 * provided by their bus types (and analogously for their modalias).
 */
static struct acpi_device *acpi_companion_match(const struct device *dev)
{
        struct acpi_device *adev;
        struct mutex *physical_node_lock;

        adev = ACPI_COMPANION(dev);
        if (!adev)
                return NULL;

        if (list_empty(&adev->pnp.ids))
                return NULL;

        physical_node_lock = &adev->physical_node_lock;
        mutex_lock(physical_node_lock);
        if (list_empty(&adev->physical_node_list)) {
                adev = NULL;
        } else {
                const struct acpi_device_physical_node *node;

                node = list_first_entry(&adev->physical_node_list,
                                        struct acpi_device_physical_node, node);
                if (node->dev != dev)
                        adev = NULL;
        }
        mutex_unlock(physical_node_lock);

        return adev;
}

static int __acpi_device_uevent_modalias(struct acpi_device *adev,
                                         struct kobj_uevent_env *env)
{
        int len;

        if (!adev)
                return -ENODEV;

        if (list_empty(&adev->pnp.ids))
                return 0;

        if (add_uevent_var(env, "MODALIAS="))
                return -ENOMEM;

        len = create_pnp_modalias(adev, &env->buf[env->buflen - 1],
                                  sizeof(env->buf) - env->buflen);
        if (len < 0)
                return len;

        env->buflen += len;
        if (!adev->data.of_compatible)
                return 0;

        if (len > 0 && add_uevent_var(env, "MODALIAS="))
                return -ENOMEM;

        len = create_of_modalias(adev, &env->buf[env->buflen - 1],
                                 sizeof(env->buf) - env->buflen);
        if (len < 0)
                return len;

        env->buflen += len;

        return 0;
}

/*
 * Creates uevent modalias field for ACPI enumerated devices.
 * Because the other buses does not support ACPI HIDs & CIDs.
 * e.g. for a device with hid:IBM0001 and cid:ACPI0001 you get:
 * "acpi:IBM0001:ACPI0001"
 */
int acpi_device_uevent_modalias(struct device *dev, struct kobj_uevent_env *env)
{
        return __acpi_device_uevent_modalias(acpi_companion_match(dev), env);
}
EXPORT_SYMBOL_GPL(acpi_device_uevent_modalias);

static int __acpi_device_modalias(struct acpi_device *adev, char *buf, int size)
{
        int len, count;

        if (!adev)
                return -ENODEV;

        if (list_empty(&adev->pnp.ids))
                return 0;

        len = create_pnp_modalias(adev, buf, size - 1);
        if (len < 0) {
                return len;
        } else if (len > 0) {
                buf[len++] = '\n';
                size -= len;
        }
        if (!adev->data.of_compatible)
                return len;

        count = create_of_modalias(adev, buf + len, size - 1);
        if (count < 0) {
                return count;
        } else if (count > 0) {
                len += count;
                buf[len++] = '\n';
        }

        return len;
}

/*
 * Creates modalias sysfs attribute for ACPI enumerated devices.
 * Because the other buses does not support ACPI HIDs & CIDs.
 * e.g. for a device with hid:IBM0001 and cid:ACPI0001 you get:
 * "acpi:IBM0001:ACPI0001"
 */
int acpi_device_modalias(struct device *dev, char *buf, int size)
{
        return __acpi_device_modalias(acpi_companion_match(dev), buf, size);
}
EXPORT_SYMBOL_GPL(acpi_device_modalias);

static ssize_t
acpi_device_modalias_show(struct device *dev, struct device_attribute *attr, char *buf) {
        return __acpi_device_modalias(to_acpi_device(dev), buf, 1024);
}
static DEVICE_ATTR(modalias, 0444, acpi_device_modalias_show, NULL);

bool acpi_scan_is_offline(struct acpi_device *adev, bool uevent)
{
        struct acpi_device_physical_node *pn;
        bool offline = true;

        /*
         * acpi_container_offline() calls this for all of the container's
         * children under the container's physical_node_lock lock.
         */
        mutex_lock_nested(&adev->physical_node_lock, SINGLE_DEPTH_NESTING);

        list_for_each_entry(pn, &adev->physical_node_list, node)
                if (device_supports_offline(pn->dev) && !pn->dev->offline) {
                        if (uevent)
                                kobject_uevent(&pn->dev->kobj, KOBJ_CHANGE);

                        offline = false;
                        break;
                }

        mutex_unlock(&adev->physical_node_lock);
        return offline;
}

static acpi_status acpi_bus_offline(acpi_handle handle, u32 lvl, void *data,
                                    void **ret_p)
{
        struct acpi_device *device = NULL;
        struct acpi_device_physical_node *pn;
        bool second_pass = (bool)data;
        acpi_status status = AE_OK;

        if (acpi_bus_get_device(handle, &device))
                return AE_OK;

        if (device->handler && !device->handler->hotplug.enabled) {
                *ret_p = &device->dev;
                return AE_SUPPORT;
        }

        mutex_lock(&device->physical_node_lock);

        list_for_each_entry(pn, &device->physical_node_list, node) {
                int ret;

                if (second_pass) {
                        /* Skip devices offlined by the first pass. */
                        if (pn->put_online)
                                continue;
                } else {
                        pn->put_online = false;
                }
                ret = device_offline(pn->dev);
                if (acpi_force_hot_remove)
                        continue;

                if (ret >= 0) {
                        pn->put_online = !ret;
                } else {
                        *ret_p = pn->dev;
                        if (second_pass) {
                                status = AE_ERROR;
                                break;
                        }
                }
        }

        mutex_unlock(&device->physical_node_lock);

        return status;
}

static acpi_status acpi_bus_online(acpi_handle handle, u32 lvl, void *data,
                                   void **ret_p)
{
        struct acpi_device *device = NULL;
        struct acpi_device_physical_node *pn;

        if (acpi_bus_get_device(handle, &device))
                return AE_OK;

        mutex_lock(&device->physical_node_lock);

        list_for_each_entry(pn, &device->physical_node_list, node)
                if (pn->put_online) {
                        device_online(pn->dev);
                        pn->put_online = false;
                }

        mutex_unlock(&device->physical_node_lock);

        return AE_OK;
}

static int acpi_scan_try_to_offline(struct acpi_device *device)
{
        acpi_handle handle = device->handle;
        struct device *errdev = NULL;
        acpi_status status;

        /*
         * Carry out two passes here and ignore errors in the first pass,
         * because if the devices in question are memory blocks and
         * CONFIG_MEMCG is set, one of the blocks may hold data structures
         * that the other blocks depend on, but it is not known in advance which
         * block holds them.
         *
         * If the first pass is successful, the second one isn't needed, though.
         */
        status = acpi_walk_namespace(ACPI_TYPE_ANY, handle, ACPI_UINT32_MAX,
                                     NULL, acpi_bus_offline, (void *)false,
                                     (void **)&errdev);
        if (status == AE_SUPPORT) {
                dev_warn(errdev, "Offline disabled.\n");
                acpi_walk_namespace(ACPI_TYPE_ANY, handle, ACPI_UINT32_MAX,
                                    acpi_bus_online, NULL, NULL, NULL);
                return -EPERM;
        }
        acpi_bus_offline(handle, 0, (void *)false, (void **)&errdev);
        if (errdev) {
                errdev = NULL;
                acpi_walk_namespace(ACPI_TYPE_ANY, handle, ACPI_UINT32_MAX,
                                    NULL, acpi_bus_offline, (void *)true,
                                    (void **)&errdev);
                if (!errdev || acpi_force_hot_remove)
                        acpi_bus_offline(handle, 0, (void *)true,
                                         (void **)&errdev);

                if (errdev && !acpi_force_hot_remove) {
                        dev_warn(errdev, "Offline failed.\n");
                        acpi_bus_online(handle, 0, NULL, NULL);
                        acpi_walk_namespace(ACPI_TYPE_ANY, handle,
                                            ACPI_UINT32_MAX, acpi_bus_online,
                                            NULL, NULL, NULL);
                        return -EBUSY;
                }
        }
        return 0;
}

static int acpi_scan_hot_remove(struct acpi_device *device)
{
        acpi_handle handle = device->handle;
        unsigned long long sta;
        acpi_status status;

        if (device->handler && device->handler->hotplug.demand_offline
            && !acpi_force_hot_remove) {
                if (!acpi_scan_is_offline(device, true))
                        return -EBUSY;
        } else {
                int error = acpi_scan_try_to_offline(device);
                if (error)
                        return error;
        }

        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                "Hot-removing device %s...\n", dev_name(&device->dev)));

        acpi_bus_trim(device);

        acpi_evaluate_lck(handle, 0);
        /*
         * TBD: _EJD support.
         */
        status = acpi_evaluate_ej0(handle);
        if (status == AE_NOT_FOUND)
                return -ENODEV;
        else if (ACPI_FAILURE(status))
                return -EIO;

        /*
         * Verify if eject was indeed successful.  If not, log an error
         * message.  No need to call _OST since _EJ0 call was made OK.
         */
        status = acpi_evaluate_integer(handle, "_STA", NULL, &sta);
        if (ACPI_FAILURE(status)) {
                acpi_handle_warn(handle,
                        "Status check after eject failed (0x%x)\n", status);
        } else if (sta & ACPI_STA_DEVICE_ENABLED) {
                acpi_handle_warn(handle,
                        "Eject incomplete - status 0x%llx\n", sta);
        }

        return 0;
}

static int acpi_scan_device_not_present(struct acpi_device *adev)
{
        if (!acpi_device_enumerated(adev)) {
                dev_warn(&adev->dev, "Still not present\n");
                return -EALREADY;
        }
        acpi_bus_trim(adev);
        return 0;
}

static int acpi_scan_device_check(struct acpi_device *adev)
{
        int error;

        acpi_bus_get_status(adev);
        if (adev->status.present || adev->status.functional) {
                /*
                 * This function is only called for device objects for which
                 * matching scan handlers exist.  The only situation in which
                 * the scan handler is not attached to this device object yet
                 * is when the device has just appeared (either it wasn't
                 * present at all before or it was removed and then added
                 * again).
                 */
                if (adev->handler) {
                        dev_warn(&adev->dev, "Already enumerated\n");
                        return -EALREADY;
                }
                error = acpi_bus_scan(adev->handle);
                if (error) {
                        dev_warn(&adev->dev, "Namespace scan failure\n");
                        return error;
                }
                if (!adev->handler) {
                        dev_warn(&adev->dev, "Enumeration failure\n");
                        error = -ENODEV;
                }
        } else {
                error = acpi_scan_device_not_present(adev);
        }
        return error;
}

static int acpi_scan_bus_check(struct acpi_device *adev)
{
        struct acpi_scan_handler *handler = adev->handler;
        struct acpi_device *child;
        int error;

        acpi_bus_get_status(adev);
        if (!(adev->status.present || adev->status.functional)) {
                acpi_scan_device_not_present(adev);
                return 0;
        }
        if (handler && handler->hotplug.scan_dependent)
                return handler->hotplug.scan_dependent(adev);

        error = acpi_bus_scan(adev->handle);
        if (error) {
                dev_warn(&adev->dev, "Namespace scan failure\n");
                return error;
        }
        list_for_each_entry(child, &adev->children, node) {
                error = acpi_scan_bus_check(child);
                if (error)
                        return error;
        }
        return 0;
}

static int acpi_generic_hotplug_event(struct acpi_device *adev, u32 type)
{
        switch (type) {
        case ACPI_NOTIFY_BUS_CHECK:
                return acpi_scan_bus_check(adev);
        case ACPI_NOTIFY_DEVICE_CHECK:
                return acpi_scan_device_check(adev);
        case ACPI_NOTIFY_EJECT_REQUEST:
        case ACPI_OST_EC_OSPM_EJECT:
                if (adev->handler && !adev->handler->hotplug.enabled) {
                        dev_info(&adev->dev, "Eject disabled\n");
                        return -EPERM;
                }
                acpi_evaluate_ost(adev->handle, ACPI_NOTIFY_EJECT_REQUEST,
                                  ACPI_OST_SC_EJECT_IN_PROGRESS, NULL);
                return acpi_scan_hot_remove(adev);
        }
        return -EINVAL;
}

void acpi_device_hotplug(struct acpi_device *adev, u32 src)
{
        u32 ost_code = ACPI_OST_SC_NON_SPECIFIC_FAILURE;
        int error = -ENODEV;

        lock_device_hotplug();
        mutex_lock(&acpi_scan_lock);

        /*
         * The device object's ACPI handle cannot become invalid as long as we
         * are holding acpi_scan_lock, but it might have become invalid before
         * that lock was acquired.
         */
        if (adev->handle == INVALID_ACPI_HANDLE)
                goto err_out;

        if (adev->flags.is_dock_station) {
                error = dock_notify(adev, src);
        } else if (adev->flags.hotplug_notify) {
                error = acpi_generic_hotplug_event(adev, src);
                if (error == -EPERM) {
                        ost_code = ACPI_OST_SC_EJECT_NOT_SUPPORTED;
                        goto err_out;
                }
        } else {
                int (*notify)(struct acpi_device *, u32);

                acpi_lock_hp_context();
                notify = adev->hp ? adev->hp->notify : NULL;
                acpi_unlock_hp_context();
                /*
                 * There may be additional notify handlers for device objects
                 * without the .event() callback, so ignore them here.
                 */
                if (notify)
                        error = notify(adev, src);
                else
                        goto out;
        }
        if (!error)
                ost_code = ACPI_OST_SC_SUCCESS;

 err_out:
        acpi_evaluate_ost(adev->handle, src, ost_code, NULL);

 out:
        acpi_bus_put_acpi_device(adev);
        mutex_unlock(&acpi_scan_lock);
        unlock_device_hotplug();
}

static ssize_t real_power_state_show(struct device *dev,
                                     struct device_attribute *attr, char *buf)
{
        struct acpi_device *adev = to_acpi_device(dev);
        int state;
        int ret;

        ret = acpi_device_get_power(adev, &state);
        if (ret)
                return ret;

        return sprintf(buf, "%s\n", acpi_power_state_string(state));
}

static DEVICE_ATTR(real_power_state, 0444, real_power_state_show, NULL);

static ssize_t power_state_show(struct device *dev,
                                struct device_attribute *attr, char *buf)
{
        struct acpi_device *adev = to_acpi_device(dev);

        return sprintf(buf, "%s\n", acpi_power_state_string(adev->power.state));
}

static DEVICE_ATTR(power_state, 0444, power_state_show, NULL);

static ssize_t
acpi_eject_store(struct device *d, struct device_attribute *attr,
                const char *buf, size_t count)
{
        struct acpi_device *acpi_device = to_acpi_device(d);
        acpi_object_type not_used;
        acpi_status status;

        if (!count || buf[0] != '1')
                return -EINVAL;

        if ((!acpi_device->handler || !acpi_device->handler->hotplug.enabled)
            && !acpi_device->driver)
                return -ENODEV;

        status = acpi_get_type(acpi_device->handle, &not_used);
        if (ACPI_FAILURE(status) || !acpi_device->flags.ejectable)
                return -ENODEV;

        get_device(&acpi_device->dev);
        status = acpi_hotplug_schedule(acpi_device, ACPI_OST_EC_OSPM_EJECT);
        if (ACPI_SUCCESS(status))
                return count;

        put_device(&acpi_device->dev);
        acpi_evaluate_ost(acpi_device->handle, ACPI_OST_EC_OSPM_EJECT,
                          ACPI_OST_SC_NON_SPECIFIC_FAILURE, NULL);
        return status == AE_NO_MEMORY ? -ENOMEM : -EAGAIN;
}

static DEVICE_ATTR(eject, 0200, NULL, acpi_eject_store);

static ssize_t
acpi_device_hid_show(struct device *dev, struct device_attribute *attr, char *buf) {
        struct acpi_device *acpi_dev = to_acpi_device(dev);

        return sprintf(buf, "%s\n", acpi_device_hid(acpi_dev));
}
static DEVICE_ATTR(hid, 0444, acpi_device_hid_show, NULL);

static ssize_t acpi_device_uid_show(struct device *dev,
                                    struct device_attribute *attr, char *buf)
{
        struct acpi_device *acpi_dev = to_acpi_device(dev);

        return sprintf(buf, "%s\n", acpi_dev->pnp.unique_id);
}
static DEVICE_ATTR(uid, 0444, acpi_device_uid_show, NULL);

static ssize_t acpi_device_adr_show(struct device *dev,
                                    struct device_attribute *attr, char *buf)
{
        struct acpi_device *acpi_dev = to_acpi_device(dev);

        return sprintf(buf, "0x%08x\n",
                       (unsigned int)(acpi_dev->pnp.bus_address));
}
static DEVICE_ATTR(adr, 0444, acpi_device_adr_show, NULL);

static ssize_t
acpi_device_path_show(struct device *dev, struct device_attribute *attr, char *buf) {
        struct acpi_device *acpi_dev = to_acpi_device(dev);
        struct acpi_buffer path = {ACPI_ALLOCATE_BUFFER, NULL};
        int result;

        result = acpi_get_name(acpi_dev->handle, ACPI_FULL_PATHNAME, &path);
        if (result)
                goto end;

        result = sprintf(buf, "%s\n", (char*)path.pointer);
        kfree(path.pointer);
end:
        return result;
}
static DEVICE_ATTR(path, 0444, acpi_device_path_show, NULL);

/* sysfs file that shows description text from the ACPI _STR method */
static ssize_t description_show(struct device *dev,
                                struct device_attribute *attr,
                                char *buf) {
        struct acpi_device *acpi_dev = to_acpi_device(dev);
        int result;

        if (acpi_dev->pnp.str_obj == NULL)
                return 0;

        /*
         * The _STR object contains a Unicode identifier for a device.
         * We need to convert to utf-8 so it can be displayed.
         */
        result = utf16s_to_utf8s(
                (wchar_t *)acpi_dev->pnp.str_obj->buffer.pointer,
                acpi_dev->pnp.str_obj->buffer.length,
                UTF16_LITTLE_ENDIAN, buf,
                PAGE_SIZE);

        buf[result++] = '\n';

        return result;
}
static DEVICE_ATTR(description, 0444, description_show, NULL);

static ssize_t
acpi_device_sun_show(struct device *dev, struct device_attribute *attr,
                     char *buf) {
        struct acpi_device *acpi_dev = to_acpi_device(dev);
        acpi_status status;
        unsigned long long sun;

        status = acpi_evaluate_integer(acpi_dev->handle, "_SUN", NULL, &sun);
        if (ACPI_FAILURE(status))
                return -ENODEV;

        return sprintf(buf, "%llu\n", sun);
}
static DEVICE_ATTR(sun, 0444, acpi_device_sun_show, NULL);

static ssize_t status_show(struct device *dev, struct device_attribute *attr,
                                char *buf) {
        struct acpi_device *acpi_dev = to_acpi_device(dev);
        acpi_status status;
        unsigned long long sta;

        status = acpi_evaluate_integer(acpi_dev->handle, "_STA", NULL, &sta);
        if (ACPI_FAILURE(status))
                return -ENODEV;

        return sprintf(buf, "%llu\n", sta);
}
static DEVICE_ATTR_RO(status);

static int acpi_device_setup_files(struct acpi_device *dev)
{
        struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
        acpi_status status;
        int result = 0;

        /*
         * Devices gotten from FADT don't have a "path" attribute
         */
        if (dev->handle) {
                result = device_create_file(&dev->dev, &dev_attr_path);
                if (result)
                        goto end;
        }

        if (!list_empty(&dev->pnp.ids)) {
                result = device_create_file(&dev->dev, &dev_attr_hid);
                if (result)
                        goto end;

                result = device_create_file(&dev->dev, &dev_attr_modalias);
                if (result)
                        goto end;
        }

        /*
         * If device has _STR, 'description' file is created
         */
        if (acpi_has_method(dev->handle, "_STR")) {
                status = acpi_evaluate_object(dev->handle, "_STR",
                                        NULL, &buffer);
                if (ACPI_FAILURE(status))
                        buffer.pointer = NULL;
                dev->pnp.str_obj = buffer.pointer;
                result = device_create_file(&dev->dev, &dev_attr_description);
                if (result)
                        goto end;
        }

        if (dev->pnp.type.bus_address)
                result = device_create_file(&dev->dev, &dev_attr_adr);
        if (dev->pnp.unique_id)
                result = device_create_file(&dev->dev, &dev_attr_uid);

        if (acpi_has_method(dev->handle, "_SUN")) {
                result = device_create_file(&dev->dev, &dev_attr_sun);
                if (result)
                        goto end;
        }

        if (acpi_has_method(dev->handle, "_STA")) {
                result = device_create_file(&dev->dev, &dev_attr_status);
                if (result)
                        goto end;
        }

        /*
         * If device has _EJ0, 'eject' file is created that is used to trigger
         * hot-removal function from userland.
         */
        if (acpi_has_method(dev->handle, "_EJ0")) {
                result = device_create_file(&dev->dev, &dev_attr_eject);
                if (result)
                        return result;
        }

        if (dev->flags.power_manageable) {
                result = device_create_file(&dev->dev, &dev_attr_power_state);
                if (result)
                        return result;

                if (dev->power.flags.power_resources)
                        result = device_create_file(&dev->dev,
                                                    &dev_attr_real_power_state);
        }

end:
        return result;
}

static void acpi_device_remove_files(struct acpi_device *dev)
{
        if (dev->flags.power_manageable) {
                device_remove_file(&dev->dev, &dev_attr_power_state);
                if (dev->power.flags.power_resources)
                        device_remove_file(&dev->dev,
                                           &dev_attr_real_power_state);
        }

        /*
         * If device has _STR, remove 'description' file
         */
        if (acpi_has_method(dev->handle, "_STR")) {
                kfree(dev->pnp.str_obj);
                device_remove_file(&dev->dev, &dev_attr_description);
        }
        /*
         * If device has _EJ0, remove 'eject' file.
         */
        if (acpi_has_method(dev->handle, "_EJ0"))
                device_remove_file(&dev->dev, &dev_attr_eject);

        if (acpi_has_method(dev->handle, "_SUN"))
                device_remove_file(&dev->dev, &dev_attr_sun);

        if (dev->pnp.unique_id)
                device_remove_file(&dev->dev, &dev_attr_uid);
        if (dev->pnp.type.bus_address)
                device_remove_file(&dev->dev, &dev_attr_adr);
        device_remove_file(&dev->dev, &dev_attr_modalias);
        device_remove_file(&dev->dev, &dev_attr_hid);
        if (acpi_has_method(dev->handle, "_STA"))
                device_remove_file(&dev->dev, &dev_attr_status);
        if (dev->handle)
                device_remove_file(&dev->dev, &dev_attr_path);
}
/* --------------------------------------------------------------------------
                        ACPI Bus operations
   -------------------------------------------------------------------------- */

/**
 * acpi_of_match_device - Match device object using the "compatible" property.
 * @adev: ACPI device object to match.
 * @of_match_table: List of device IDs to match against.
 *
 * If @dev has an ACPI companion which has the special PRP0001 device ID in its
 * list of identifiers and a _DSD object with the "compatible" property, use
 * that property to match against the given list of identifiers.
 */
static bool acpi_of_match_device(struct acpi_device *adev,
                                 const struct of_device_id *of_match_table)
{
        const union acpi_object *of_compatible, *obj;
        int i, nval;

        if (!adev)
                return false;

        of_compatible = adev->data.of_compatible;
        if (!of_match_table || !of_compatible)
                return false;

        if (of_compatible->type == ACPI_TYPE_PACKAGE) {

                nval = of_compatible->package.count;
                obj = of_compatible->package.elements;
        } else { /* Must be ACPI_TYPE_STRING. */
                nval = 1;
                obj = of_compatible;
        }
        /* Now we can look for the driver DT compatible strings */
        for (i = 0; i < nval; i++, obj++) {
                const struct of_device_id *id;

                for (id = of_match_table; id->compatible[0]; id++)
                        if (!strcasecmp(obj->string.pointer, id->compatible))
                                return true;
        }

        return false;
}

static const struct acpi_device_id *__acpi_match_device(
        struct acpi_device *device,
        const struct acpi_device_id *ids,
        const struct of_device_id *of_ids)
{
        const struct acpi_device_id *id;
        struct acpi_hardware_id *hwid;

        /*
         * If the device is not present, it is unnecessary to load device
         * driver for it.
         */
        if (!device || !device->status.present)
                return NULL;

        list_for_each_entry(hwid, &device->pnp.ids, list) {
                /* First, check the ACPI/PNP IDs provided by the caller. */
                for (id = ids; id->id[0]; id++)
                        if (!strcmp((char *) id->id, hwid->id))
                                return id;

                /*
                 * Next, check the special "PRP0001" ID and try to match the
                 * "compatible" property if found.
                 *
                 * The id returned by the below is not valid, but the only
                 * caller passing non-NULL of_ids here is only interested in
                 * whether or not the return value is NULL.
                 */
                if (!strcmp("PRP0001", hwid->id)
                    && acpi_of_match_device(device, of_ids))
                        return id;
        }
        return NULL;
}

/**
 * acpi_match_device - Match a struct device against a given list of ACPI IDs
 * @ids: Array of struct acpi_device_id object to match against.
 * @dev: The device structure to match.
 *
 * Check if @dev has a valid ACPI handle and if there is a struct acpi_device
 * object for that handle and use that object to match against a given list of
 * device IDs.
 *
 * Return a pointer to the first matching ID on success or %NULL on failure.
 */
const struct acpi_device_id *acpi_match_device(const struct acpi_device_id *ids,
                                               const struct device *dev)
{
        return __acpi_match_device(acpi_companion_match(dev), ids, NULL);
}
EXPORT_SYMBOL_GPL(acpi_match_device);

int acpi_match_device_ids(struct acpi_device *device,
                          const struct acpi_device_id *ids)
{
        return __acpi_match_device(device, ids, NULL) ? 0 : -ENOENT;
}
EXPORT_SYMBOL(acpi_match_device_ids);

bool acpi_driver_match_device(struct device *dev,
                              const struct device_driver *drv)
{
        if (!drv->acpi_match_table)
                return acpi_of_match_device(ACPI_COMPANION(dev),
                                            drv->of_match_table);

        return !!__acpi_match_device(acpi_companion_match(dev),
                                     drv->acpi_match_table, drv->of_match_table);
}
EXPORT_SYMBOL_GPL(acpi_driver_match_device);

static void acpi_free_power_resources_lists(struct acpi_device *device)
{
        int i;

        if (device->wakeup.flags.valid)
                acpi_power_resources_list_free(&device->wakeup.resources);

        if (!device->power.flags.power_resources)
                return;

        for (i = ACPI_STATE_D0; i <= ACPI_STATE_D3_HOT; i++) {
                struct acpi_device_power_state *ps = &device->power.states[i];
                acpi_power_resources_list_free(&ps->resources);
        }
}

static void acpi_device_release(struct device *dev)
{
        struct acpi_device *acpi_dev = to_acpi_device(dev);

        acpi_free_properties(acpi_dev);
        acpi_free_pnp_ids(&acpi_dev->pnp);
        acpi_free_power_resources_lists(acpi_dev);
        kfree(acpi_dev);
}

static int acpi_bus_match(struct device *dev, struct device_driver *drv)
{
        struct acpi_device *acpi_dev = to_acpi_device(dev);
        struct acpi_driver *acpi_drv = to_acpi_driver(drv);

        return acpi_dev->flags.match_driver
                && !acpi_match_device_ids(acpi_dev, acpi_drv->ids);
}

static int acpi_device_uevent(struct device *dev, struct kobj_uevent_env *env)
{
        return __acpi_device_uevent_modalias(to_acpi_device(dev), env);
}

static void acpi_device_notify(acpi_handle handle, u32 event, void *data)
{
        struct acpi_device *device = data;

        device->driver->ops.notify(device, event);
}

static void acpi_device_notify_fixed(void *data)
{
        struct acpi_device *device = data;

        /* Fixed hardware devices have no handles */
        acpi_device_notify(NULL, ACPI_FIXED_HARDWARE_EVENT, device);
}

static u32 acpi_device_fixed_event(void *data)
{
        acpi_os_execute(OSL_NOTIFY_HANDLER, acpi_device_notify_fixed, data);
        return ACPI_INTERRUPT_HANDLED;
}

static int acpi_device_install_notify_handler(struct acpi_device *device)
{
        acpi_status status;

        if (device->device_type == ACPI_BUS_TYPE_POWER_BUTTON)
                status =
                    acpi_install_fixed_event_handler(ACPI_EVENT_POWER_BUTTON,
                                                     acpi_device_fixed_event,
                                                     device);
        else if (device->device_type == ACPI_BUS_TYPE_SLEEP_BUTTON)
                status =
                    acpi_install_fixed_event_handler(ACPI_EVENT_SLEEP_BUTTON,
                                                     acpi_device_fixed_event,
                                                     device);
        else
                status = acpi_install_notify_handler(device->handle,
                                                     ACPI_DEVICE_NOTIFY,
                                                     acpi_device_notify,
                                                     device);

        if (ACPI_FAILURE(status))
                return -EINVAL;
        return 0;
}

static void acpi_device_remove_notify_handler(struct acpi_device *device)
{
        if (device->device_type == ACPI_BUS_TYPE_POWER_BUTTON)
                acpi_remove_fixed_event_handler(ACPI_EVENT_POWER_BUTTON,
                                                acpi_device_fixed_event);
        else if (device->device_type == ACPI_BUS_TYPE_SLEEP_BUTTON)
                acpi_remove_fixed_event_handler(ACPI_EVENT_SLEEP_BUTTON,
                                                acpi_device_fixed_event);
        else
                acpi_remove_notify_handler(device->handle, ACPI_DEVICE_NOTIFY,
                                           acpi_device_notify);
}

static int acpi_device_probe(struct device *dev)
{
        struct acpi_device *acpi_dev = to_acpi_device(dev);
        struct acpi_driver *acpi_drv = to_acpi_driver(dev->driver);
        int ret;

        if (acpi_dev->handler && !acpi_is_pnp_device(acpi_dev))
                return -EINVAL;

        if (!acpi_drv->ops.add)
                return -ENOSYS;

        ret = acpi_drv->ops.add(acpi_dev);
        if (ret)
                return ret;

        acpi_dev->driver = acpi_drv;
        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                          "Driver [%s] successfully bound to device [%s]\n",
                          acpi_drv->name, acpi_dev->pnp.bus_id));

        if (acpi_drv->ops.notify) {
                ret = acpi_device_install_notify_handler(acpi_dev);
                if (ret) {
                        if (acpi_drv->ops.remove)
                                acpi_drv->ops.remove(acpi_dev);

                        acpi_dev->driver = NULL;
                        acpi_dev->driver_data = NULL;
                        return ret;
                }
        }

        ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found driver [%s] for device [%s]\n",
                          acpi_drv->name, acpi_dev->pnp.bus_id));
        get_device(dev);
        return 0;
}

static int acpi_device_remove(struct device * dev)
{
        struct acpi_device *acpi_dev = to_acpi_device(dev);
        struct acpi_driver *acpi_drv = acpi_dev->driver;

        if (acpi_drv) {
                if (acpi_drv->ops.notify)
                        acpi_device_remove_notify_handler(acpi_dev);
                if (acpi_drv->ops.remove)
                        acpi_drv->ops.remove(acpi_dev);
        }
        acpi_dev->driver = NULL;
        acpi_dev->driver_data = NULL;

        put_device(dev);
        return 0;
}

struct bus_type acpi_bus_type = {
        .name           = "acpi",
        .match          = acpi_bus_match,
        .probe          = acpi_device_probe,
        .remove         = acpi_device_remove,
        .uevent         = acpi_device_uevent,
};

static void acpi_device_del(struct acpi_device *device)
{
        mutex_lock(&acpi_device_lock);
        if (device->parent)
                list_del(&device->node);

        list_del(&device->wakeup_list);
        mutex_unlock(&acpi_device_lock);

        acpi_power_add_remove_device(device, false);
        acpi_device_remove_files(device);
        if (device->remove)
                device->remove(device);

        device_del(&device->dev);
}

static LIST_HEAD(acpi_device_del_list);
static DEFINE_MUTEX(acpi_device_del_lock);

static void acpi_device_del_work_fn(struct work_struct *work_not_used)
{
        for (;;) {
                struct acpi_device *adev;

                mutex_lock(&acpi_device_del_lock);

                if (list_empty(&acpi_device_del_list)) {
                        mutex_unlock(&acpi_device_del_lock);
                        break;
                }
                adev = list_first_entry(&acpi_device_del_list,
                                        struct acpi_device, del_list);
                list_del(&adev->del_list);

                mutex_unlock(&acpi_device_del_lock);

                acpi_device_del(adev);
                /*
                 * Drop references to all power resources that might have been
                 * used by the device.
                 */
                acpi_power_transition(adev, ACPI_STATE_D3_COLD);
                put_device(&adev->dev);
        }
}

/**
 * acpi_scan_drop_device - Drop an ACPI device object.
 * @handle: Handle of an ACPI namespace node, not used.
 * @context: Address of the ACPI device object to drop.
 *
 * This is invoked by acpi_ns_delete_node() during the removal of the ACPI
 * namespace node the device object pointed to by @context is attached to.
 *
 * The unregistration is carried out asynchronously to avoid running
 * acpi_device_del() under the ACPICA's namespace mutex and the list is used to
 * ensure the correct ordering (the device objects must be unregistered in the
 * same order in which the corresponding namespace nodes are deleted).
 */
static void acpi_scan_drop_device(acpi_handle handle, void *context)
{
        static DECLARE_WORK(work, acpi_device_del_work_fn);
        struct acpi_device *adev = context;

        mutex_lock(&acpi_device_del_lock);

        /*
         * Use the ACPI hotplug workqueue which is ordered, so this work item
         * won't run after any hotplug work items submitted subsequently.  That
         * prevents attempts to register device objects identical to those being
         * deleted from happening concurrently (such attempts result from
         * hotplug events handled via the ACPI hotplug workqueue).  It also will
         * run after all of the work items submitted previosuly, which helps
         * those work items to ensure that they are not accessing stale device
         * objects.
         */
        if (list_empty(&acpi_device_del_list))
                acpi_queue_hotplug_work(&work);

        list_add_tail(&adev->del_list, &acpi_device_del_list);
        /* Make acpi_ns_validate_handle() return NULL for this handle. */
        adev->handle = INVALID_ACPI_HANDLE;

        mutex_unlock(&acpi_device_del_lock);
}

static int acpi_get_device_data(acpi_handle handle, struct acpi_device **device,
                                void (*callback)(void *))
{
        acpi_status status;

        if (!device)
                return -EINVAL;

        status = acpi_get_data_full(handle, acpi_scan_drop_device,
                                    (void **)device, callback);
        if (ACPI_FAILURE(status) || !*device) {
                ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No context for object [%p]\n",
                                  handle));
                return -ENODEV;
        }
        return 0;
}

int acpi_bus_get_device(acpi_handle handle, struct acpi_device **device)
{
        return acpi_get_device_data(handle, device, NULL);
}
EXPORT_SYMBOL(acpi_bus_get_device);

static void get_acpi_device(void *dev)
{
        if (dev)
                get_device(&((struct acpi_device *)dev)->dev);
}

struct acpi_device *acpi_bus_get_acpi_device(acpi_handle handle)
{
        struct acpi_device *adev = NULL;

        acpi_get_device_data(handle, &adev, get_acpi_device);
        return adev;
}

void acpi_bus_put_acpi_device(struct acpi_device *adev)
{
        put_device(&adev->dev);
}

int acpi_device_add(struct acpi_device *device,
                    void (*release)(struct device *))
{
        int result;
        struct acpi_device_bus_id *acpi_device_bus_id, *new_bus_id;
        int found = 0;

        if (device->handle) {
                acpi_status status;

                status = acpi_attach_data(device->handle, acpi_scan_drop_device,
                                          device);
                if (ACPI_FAILURE(status)) {
                        acpi_handle_err(device->handle,
                                        "Unable to attach device data\n");
                        return -ENODEV;
                }
        }

        /*
         * Linkage
         * -------
         * Link this device to its parent and siblings.
         */
        INIT_LIST_HEAD(&device->children);
        INIT_LIST_HEAD(&device->node);
        INIT_LIST_HEAD(&device->wakeup_list);
        INIT_LIST_HEAD(&device->physical_node_list);
        INIT_LIST_HEAD(&device->del_list);
        mutex_init(&device->physical_node_lock);

        new_bus_id = kzalloc(sizeof(struct acpi_device_bus_id), GFP_KERNEL);
        if (!new_bus_id) {
                pr_err(PREFIX "Memory allocation error\n");
                result = -ENOMEM;
                goto err_detach;
        }

        mutex_lock(&acpi_device_lock);
        /*
         * Find suitable bus_id and instance number in acpi_bus_id_list
         * If failed, create one and link it into acpi_bus_id_list
         */
        list_for_each_entry(acpi_device_bus_id, &acpi_bus_id_list, node) {
                if (!strcmp(acpi_device_bus_id->bus_id,
                            acpi_device_hid(device))) {
                        acpi_device_bus_id->instance_no++;
                        found = 1;
                        kfree(new_bus_id);
                        break;
                }
        }
        if (!found) {
                acpi_device_bus_id = new_bus_id;
                strcpy(acpi_device_bus_id->bus_id, acpi_device_hid(device));
                acpi_device_bus_id->instance_no = 0;
                list_add_tail(&acpi_device_bus_id->node, &acpi_bus_id_list);
        }
        dev_set_name(&device->dev, "%s:%02x", acpi_device_bus_id->bus_id, acpi_device_bus_id->instance_no);

        if (device->parent)
                list_add_tail(&device->node, &device->parent->children);

        if (device->wakeup.flags.valid)
                list_add_tail(&device->wakeup_list, &acpi_wakeup_device_list);
        mutex_unlock(&acpi_device_lock);

        if (device->parent)
                device->dev.parent = &device->parent->dev;
        device->dev.bus = &acpi_bus_type;
        device->dev.release = release;
        result = device_add(&device->dev);
        if (result) {
                dev_err(&device->dev, "Error registering device\n");
                goto err;
        }

        result = acpi_device_setup_files(device);
        if (result)
                printk(KERN_ERR PREFIX "Error creating sysfs interface for device %s\n",
                       dev_name(&device->dev));

        return 0;

 err:
        mutex_lock(&acpi_device_lock);
        if (device->parent)
                list_del(&device->node);
        list_del(&device->wakeup_list);
        mutex_unlock(&acpi_device_lock);

 err_detach:
        acpi_detach_data(device->handle, acpi_scan_drop_device);
        return result;
}

struct acpi_device *acpi_get_next_child(struct device *dev,
                                        struct acpi_device *child)
{
        struct acpi_device *adev = ACPI_COMPANION(dev);
        struct list_head *head, *next;

        if (!adev)
                return NULL;

        head = &adev->children;
        if (list_empty(head))
                return NULL;

        if (!child)
                return list_first_entry(head, struct acpi_device, node);

        next = child->node.next;
        return next == head ? NULL : list_entry(next, struct acpi_device, node);
}

/* --------------------------------------------------------------------------
                                 Driver Management
   -------------------------------------------------------------------------- */
/**
 * acpi_bus_register_driver - register a driver with the ACPI bus
 * @driver: driver being registered
 *
 * Registers a driver with the ACPI bus.  Searches the namespace for all
 * devices that match the driver's criteria and binds.  Returns zero for
 * success or a negative error status for failure.
 */
int acpi_bus_register_driver(struct acpi_driver *driver)
{
        int ret;

        if (acpi_disabled)
                return -ENODEV;
        driver->drv.name = driver->name;
        driver->drv.bus = &acpi_bus_type;
        driver->drv.owner = driver->owner;

        ret = driver_register(&driver->drv);
        return ret;
}

EXPORT_SYMBOL(acpi_bus_register_driver);

/**
 * acpi_bus_unregister_driver - unregisters a driver with the ACPI bus
 * @driver: driver to unregister
 *
 * Unregisters a driver with the ACPI bus.  Searches the namespace for all
 * devices that match the driver's criteria and unbinds.
 */
void acpi_bus_unregister_driver(struct acpi_driver *driver)
{
        driver_unregister(&driver->drv);
}

EXPORT_SYMBOL(acpi_bus_unregister_driver);

/* --------------------------------------------------------------------------
                                 Device Enumeration
   -------------------------------------------------------------------------- */
static struct acpi_device *acpi_bus_get_parent(acpi_handle handle)
{
        struct acpi_device *device = NULL;
        acpi_status status;

        /*
         * Fixed hardware devices do not appear in the namespace and do not
         * have handles, but we fabricate acpi_devices for them, so we have
         * to deal with them specially.
         */
        if (!handle)
                return acpi_root;

        do {
                status = acpi_get_parent(handle, &handle);
                if (ACPI_FAILURE(status))
                        return status == AE_NULL_ENTRY ? NULL : acpi_root;
        } while (acpi_bus_get_device(handle, &device));
        return device;
}

acpi_status
acpi_bus_get_ejd(acpi_handle handle, acpi_handle *ejd)
{
        acpi_status status;
        acpi_handle tmp;
        struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
        union acpi_object *obj;

        status = acpi_get_handle(handle, "_EJD", &tmp);
        if (ACPI_FAILURE(status))
                return status;

        status = acpi_evaluate_object(handle, "_EJD", NULL, &buffer);
        if (ACPI_SUCCESS(status)) {
                obj = buffer.pointer;
                status = acpi_get_handle(ACPI_ROOT_OBJECT, obj->string.pointer,
                                         ejd);
                kfree(buffer.pointer);
        }
        return status;
}
EXPORT_SYMBOL_GPL(acpi_bus_get_ejd);

static int acpi_bus_extract_wakeup_device_power_package(acpi_handle handle,
                                        struct acpi_device_wakeup *wakeup)
{
        struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
        union acpi_object *package = NULL;
        union acpi_object *element = NULL;
        acpi_status status;
        int err = -ENODATA;

        if (!wakeup)
                return -EINVAL;

        INIT_LIST_HEAD(&wakeup->resources);

        /* _PRW */
        status = acpi_evaluate_object(handle, "_PRW", NULL, &buffer);
        if (ACPI_FAILURE(status)) {
                ACPI_EXCEPTION((AE_INFO, status, "Evaluating _PRW"));
                return err;
        }

        package = (union acpi_object *)buffer.pointer;

        if (!package || package->package.count < 2)
                goto out;

        element = &(package->package.elements[0]);
        if (!element)
                goto out;

        if (element->type == ACPI_TYPE_PACKAGE) {
                if ((element->package.count < 2) ||
                    (element->package.elements[0].type !=
                     ACPI_TYPE_LOCAL_REFERENCE)
                    || (element->package.elements[1].type != ACPI_TYPE_INTEGER))
                        goto out;

                wakeup->gpe_device =
                    element->package.elements[0].reference.handle;
                wakeup->gpe_number =
                    (u32) element->package.elements[1].integer.value;
        } else if (element->type == ACPI_TYPE_INTEGER) {
                wakeup->gpe_device = NULL;
                wakeup->gpe_number = element->integer.value;
        } else {
                goto out;
        }

        element = &(package->package.elements[1]);
        if (element->type != ACPI_TYPE_INTEGER)
                goto out;

        wakeup->sleep_state = element->integer.value;

        err = acpi_extract_power_resources(package, 2, &wakeup->resources);
        if (err)
                goto out;

        if (!list_empty(&wakeup->resources)) {
                int sleep_state;

                err = acpi_power_wakeup_list_init(&wakeup->resources,
                                                  &sleep_state);
                if (err) {
                        acpi_handle_warn(handle, "Retrieving current states "
                                         "of wakeup power resources failed\n");
                        acpi_power_resources_list_free(&wakeup->resources);
                        goto out;
                }
                if (sleep_state < wakeup->sleep_state) {
                        acpi_handle_warn(handle, "Overriding _PRW sleep state "
                                         "(S%d) by S%d from power resources\n",
                                         (int)wakeup->sleep_state, sleep_state);
                        wakeup->sleep_state = sleep_state;
                }
        }

 out:
        kfree(buffer.pointer);
        return err;
}

static void acpi_wakeup_gpe_init(struct acpi_device *device)
{
        struct acpi_device_id button_device_ids[] = {
                {"PNP0C0C", 0},
                {"PNP0C0D", 0},
                {"PNP0C0E", 0},
                {"", 0},
        };
        struct acpi_device_wakeup *wakeup = &device->wakeup;
        acpi_status status;
        acpi_event_status event_status;

        wakeup->flags.notifier_present = 0;

        /* Power button, Lid switch always enable wakeup */
        if (!acpi_match_device_ids(device, button_device_ids)) {
                wakeup->flags.run_wake = 1;
                if (!acpi_match_device_ids(device, &button_device_ids[1])) {
                        /* Do not use Lid/sleep button for S5 wakeup */
                        if (wakeup->sleep_state == ACPI_STATE_S5)
                                wakeup->sleep_state = ACPI_STATE_S4;
                }
                acpi_mark_gpe_for_wake(wakeup->gpe_device, wakeup->gpe_number);
                device_set_wakeup_capable(&device->dev, true);
                return;
        }

        acpi_setup_gpe_for_wake(device->handle, wakeup->gpe_device,
                                wakeup->gpe_number);
        status = acpi_get_gpe_status(wakeup->gpe_device, wakeup->gpe_number,
                                     &event_status);
        if (ACPI_FAILURE(status))
                return;

        wakeup->flags.run_wake = !!(event_status & ACPI_EVENT_FLAG_HAS_HANDLER);
}

static void acpi_bus_get_wakeup_device_flags(struct acpi_device *device)
{
        int err;

        /* Presence of _PRW indicates wake capable */
        if (!acpi_has_method(device->handle, "_PRW"))
                return;

        err = acpi_bus_extract_wakeup_device_power_package(device->handle,
                                                           &device->wakeup);
        if (err) {
                dev_err(&device->dev, "_PRW evaluation error: %d\n", err);
                return;
        }

        device->wakeup.flags.valid = 1;
        device->wakeup.prepare_count = 0;
        acpi_wakeup_gpe_init(device);
        /* Call _PSW/_DSW object to disable its ability to wake the sleeping
         * system for the ACPI device with the _PRW object.
         * The _PSW object is depreciated in ACPI 3.0 and is replaced by _DSW.
         * So it is necessary to call _DSW object first. Only when it is not
         * present will the _PSW object used.
         */
        err = acpi_device_sleep_wake(device, 0, 0, 0);
        if (err)
                ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                                "error in _DSW or _PSW evaluation\n"));
}

static void acpi_bus_init_power_state(struct acpi_device *device, int state)
{
        struct acpi_device_power_state *ps = &device->power.states[state];
        char pathname[5] = { '_', 'P', 'R', '0' + state, '\0' };
        struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
        acpi_status status;

        INIT_LIST_HEAD(&ps->resources);

        /* Evaluate "_PRx" to get referenced power resources */
        status = acpi_evaluate_object(device->handle, pathname, NULL, &buffer);
        if (ACPI_SUCCESS(status)) {
                union acpi_object *package = buffer.pointer;

                if (buffer.length && package
                    && package->type == ACPI_TYPE_PACKAGE
                    && package->package.count) {
                        int err = acpi_extract_power_resources(package, 0,
                                                               &ps->resources);
                        if (!err)
                                device->power.flags.power_resources = 1;
                }
                ACPI_FREE(buffer.pointer);
        }

        /* Evaluate "_PSx" to see if we can do explicit sets */
        pathname[2] = 'S';
        if (acpi_has_method(device->handle, pathname))
                ps->flags.explicit_set = 1;

        /*
         * State is valid if there are means to put the device into it.
         * D3hot is only valid if _PR3 present.
         */
        if (!list_empty(&ps->resources)
            || (ps->flags.explicit_set && state < ACPI_STATE_D3_HOT)) {
                ps->flags.valid = 1;
                ps->flags.os_accessible = 1;
        }

        ps->power = -1;         /* Unknown - driver assigned */
        ps->latency = -1;       /* Unknown - driver assigned */
}

static void acpi_bus_get_power_flags(struct acpi_device *device)
{
        u32 i;

        /* Presence of _PS0|_PR0 indicates 'power manageable' */
        if (!acpi_has_method(device->handle, "_PS0") &&
            !acpi_has_method(device->handle, "_PR0"))
                return;

        device->flags.power_manageable = 1;

        /*
         * Power Management Flags
         */
        if (acpi_has_method(device->handle, "_PSC"))
                device->power.flags.explicit_get = 1;

        if (acpi_has_method(device->handle, "_IRC"))
                device->power.flags.inrush_current = 1;

        if (acpi_has_method(device->handle, "_DSW"))
                device->power.flags.dsw_present = 1;

        /*
         * Enumerate supported power management states
         */
        for (i = ACPI_STATE_D0; i <= ACPI_STATE_D3_HOT; i++)
                acpi_bus_init_power_state(device, i);

        INIT_LIST_HEAD(&device->power.states[ACPI_STATE_D3_COLD].resources);

        /* Set defaults for D0 and D3 states (always valid) */
        device->power.states[ACPI_STATE_D0].flags.valid = 1;
        device->power.states[ACPI_STATE_D0].power = 100;
        device->power.states[ACPI_STATE_D3_COLD].flags.valid = 1;
        device->power.states[ACPI_STATE_D3_COLD].power = 0;

        /* Set D3cold's explicit_set flag if _PS3 exists. */
        if (device->power.states[ACPI_STATE_D3_HOT].flags.explicit_set)
                device->power.states[ACPI_STATE_D3_COLD].flags.explicit_set = 1;

        /* Presence of _PS3 or _PRx means we can put the device into D3 cold */
        if (device->power.states[ACPI_STATE_D3_HOT].flags.explicit_set ||
                        device->power.flags.power_resources)
                device->power.states[ACPI_STATE_D3_COLD].flags.os_accessible = 1;

        if (acpi_bus_init_power(device))
                device->flags.power_manageable = 0;
}

static void acpi_bus_get_flags(struct acpi_device *device)
{
        /* Presence of _STA indicates 'dynamic_status' */
        if (acpi_has_method(device->handle, "_STA"))
                device->flags.dynamic_status = 1;

        /* Presence of _RMV indicates 'removable' */
        if (acpi_has_method(device->handle, "_RMV"))
                device->flags.removable = 1;

        /* Presence of _EJD|_EJ0 indicates 'ejectable' */
        if (acpi_has_method(device->handle, "_EJD") ||
            acpi_has_method(device->handle, "_EJ0"))
                device->flags.ejectable = 1;
}

static void acpi_device_get_busid(struct acpi_device *device)
{
        char bus_id[5] = { '?', 0 };
        struct acpi_buffer buffer = { sizeof(bus_id), bus_id };
        int i = 0;

        /*
         * Bus ID
         * ------
         * The device's Bus ID is simply the object name.
         * TBD: Shouldn't this value be unique (within the ACPI namespace)?
         */
        if (ACPI_IS_ROOT_DEVICE(device)) {
                strcpy(device->pnp.bus_id, "ACPI");
                return;
        }

        switch (device->device_type) {
        case ACPI_BUS_TYPE_POWER_BUTTON:
                strcpy(device->pnp.bus_id, "PWRF");
                break;
        case ACPI_BUS_TYPE_SLEEP_BUTTON:
                strcpy(device->pnp.bus_id, "SLPF");
                break;
        default:
                acpi_get_name(device->handle, ACPI_SINGLE_NAME, &buffer);
                /* Clean up trailing underscores (if any) */
                for (i = 3; i > 1; i--) {
                        if (bus_id[i] == '_')
                                bus_id[i] = '\0';
                        else
                                break;
                }
                strcpy(device->pnp.bus_id, bus_id);
                break;
        }
}

/*
 * acpi_ata_match - see if an acpi object is an ATA device
 *
 * If an acpi object has one of the ACPI ATA methods defined,
 * then we can safely call it an ATA device.
 */
bool acpi_ata_match(acpi_handle handle)
{
        return acpi_has_method(handle, "_GTF") ||
               acpi_has_method(handle, "_GTM") ||
               acpi_has_method(handle, "_STM") ||
               acpi_has_method(handle, "_SDD");
}

/*
 * acpi_bay_match - see if an acpi object is an ejectable driver bay
 *
 * If an acpi object is ejectable and has one of the ACPI ATA methods defined,
 * then we can safely call it an ejectable drive bay
 */
bool acpi_bay_match(acpi_handle handle)
{
        acpi_handle phandle;

        if (!acpi_has_method(handle, "_EJ0"))
                return false;
        if (acpi_ata_match(handle))
                return true;
        if (ACPI_FAILURE(acpi_get_parent(handle, &phandle)))
                return false;

        return acpi_ata_match(phandle);
}

bool acpi_device_is_battery(struct acpi_device *adev)
{
        struct acpi_hardware_id *hwid;

        list_for_each_entry(hwid, &adev->pnp.ids, list)
                if (!strcmp("PNP0C0A", hwid->id))
                        return true;

        return false;
}

static bool is_ejectable_bay(struct acpi_device *adev)
{
        acpi_handle handle = adev->handle;

        if (acpi_has_method(handle, "_EJ0") && acpi_device_is_battery(adev))
                return true;

        return acpi_bay_match(handle);
}

/*
 * acpi_dock_match - see if an acpi object has a _DCK method
 */
bool acpi_dock_match(acpi_handle handle)
{
        return acpi_has_method(handle, "_DCK");
}

const char *acpi_device_hid(struct acpi_device *device)
{
        struct acpi_hardware_id *hid;

        if (list_empty(&device->pnp.ids))
                return dummy_hid;

        hid = list_first_entry(&device->pnp.ids, struct acpi_hardware_id, list);
        return hid->id;
}
EXPORT_SYMBOL(acpi_device_hid);

static void acpi_add_id(struct acpi_device_pnp *pnp, const char *dev_id)
{
        struct acpi_hardware_id *id;

        id = kmalloc(sizeof(*id), GFP_KERNEL);
        if (!id)
                return;

        id->id = kstrdup(dev_id, GFP_KERNEL);
        if (!id->id) {
                kfree(id);
                return;
        }

        list_add_tail(&id->list, &pnp->ids);
        pnp->type.hardware_id = 1;
}

/*
 * Old IBM workstations have a DSDT bug wherein the SMBus object
 * lacks the SMBUS01 HID and the methods do not have the necessary "_"
 * prefix.  Work around this.
 */
static bool acpi_ibm_smbus_match(acpi_handle handle)
{
        char node_name[ACPI_PATH_SEGMENT_LENGTH];
        struct acpi_buffer path = { sizeof(node_name), node_name };

        if (!dmi_name_in_vendors("IBM"))
                return false;

        /* Look for SMBS object */
        if (ACPI_FAILURE(acpi_get_name(handle, ACPI_SINGLE_NAME, &path)) ||
            strcmp("SMBS", path.pointer))
                return false;

        /* Does it have the necessary (but misnamed) methods? */
        if (acpi_has_method(handle, "SBI") &&
            acpi_has_method(handle, "SBR") &&

            acpi_has_method(handle, "SBW"))
                return true;

        return false;
}

static bool acpi_object_is_system_bus(acpi_handle handle)
{
        acpi_handle tmp;

        if (ACPI_SUCCESS(acpi_get_handle(NULL, "\\_SB", &tmp)) &&
            tmp == handle)
                return true;
        if (ACPI_SUCCESS(acpi_get_handle(NULL, "\\_TZ", &tmp)) &&
            tmp == handle)
                return true;

        return false;
}

static void acpi_set_pnp_ids(acpi_handle handle, struct acpi_device_pnp *pnp,
                                int device_type)
{
        acpi_status status;
        struct acpi_device_info *info;
        struct acpi_pnp_device_id_list *cid_list;
        int i;

        switch (device_type) {
        case ACPI_BUS_TYPE_DEVICE:
                if (handle == ACPI_ROOT_OBJECT) {
                        acpi_add_id(pnp, ACPI_SYSTEM_HID);
                        break;
                }

                status = acpi_get_object_info(handle, &info);
                if (ACPI_FAILURE(status)) {
                        pr_err(PREFIX "%s: Error reading device info\n",
                                        __func__);
                        return;
                }

                if (info->valid & ACPI_VALID_HID) {
                        acpi_add_id(pnp, info->hardware_id.string);
                        pnp->type.platform_id = 1;
                }
                if (info->valid & ACPI_VALID_CID) {
                        cid_list = &info->compatible_id_list;
                        for (i = 0; i < cid_list->count; i++)
                                acpi_add_id(pnp, cid_list->ids[i].string);
                }
                if (info->valid & ACPI_VALID_ADR) {
                        pnp->bus_address = info->address;
                        pnp->type.bus_address = 1;
                }
                if (info->valid & ACPI_VALID_UID)
                        pnp->unique_id = kstrdup(info->unique_id.string,
                                                        GFP_KERNEL);

                kfree(info);

                /*
                 * Some devices don't reliably have _HIDs & _CIDs, so add
                 * synthetic HIDs to make sure drivers can find them.
                 */
                if (acpi_is_video_device(handle))
                        acpi_add_id(pnp, ACPI_VIDEO_HID);
                else if (acpi_bay_match(handle))
                        acpi_add_id(pnp, ACPI_BAY_HID);
                else if (acpi_dock_match(handle))
                        acpi_add_id(pnp, ACPI_DOCK_HID);
                else if (acpi_ibm_smbus_match(handle))
                        acpi_add_id(pnp, ACPI_SMBUS_IBM_HID);
                else if (list_empty(&pnp->ids) &&
                         acpi_object_is_system_bus(handle)) {
                        /* \_SB, \_TZ, LNXSYBUS */
                        acpi_add_id(pnp, ACPI_BUS_HID);
                        strcpy(pnp->device_name, ACPI_BUS_DEVICE_NAME);
                        strcpy(pnp->device_class, ACPI_BUS_CLASS);
                }

                break;
        case ACPI_BUS_TYPE_POWER:
                acpi_add_id(pnp, ACPI_POWER_HID);
                break;
        case ACPI_BUS_TYPE_PROCESSOR:
                acpi_add_id(pnp, ACPI_PROCESSOR_OBJECT_HID);
                break;
        case ACPI_BUS_TYPE_THERMAL:
                acpi_add_id(pnp, ACPI_THERMAL_HID);
                break;
        case ACPI_BUS_TYPE_POWER_BUTTON:
                acpi_add_id(pnp, ACPI_BUTTON_HID_POWERF);
                break;
        case ACPI_BUS_TYPE_SLEEP_BUTTON:
                acpi_add_id(pnp, ACPI_BUTTON_HID_SLEEPF);
                break;
        }
}

void acpi_free_pnp_ids(struct acpi_device_pnp *pnp)
{
        struct acpi_hardware_id *id, *tmp;

        list_for_each_entry_safe(id, tmp, &pnp->ids, list) {
                kfree(id->id);
                kfree(id);
        }
        kfree(pnp->unique_id);
}

void acpi_init_device_object(struct acpi_device *device, acpi_handle handle,
                             int type, unsigned long long sta)
{
        INIT_LIST_HEAD(&device->pnp.ids);
        device->device_type = type;
        device->handle = handle;
        device->parent = acpi_bus_get_parent(handle);
        device->fwnode.type = FWNODE_ACPI;
        acpi_set_device_status(device, sta);
        acpi_device_get_busid(device);
        acpi_set_pnp_ids(handle, &device->pnp, type);
        acpi_init_properties(device);
        acpi_bus_get_flags(device);
        device->flags.match_driver = false;
        device->flags.initialized = true;
        device->flags.visited = false;
        device_initialize(&device->dev);
        dev_set_uevent_suppress(&device->dev, true);
}

void acpi_device_add_finalize(struct acpi_device *device)
{
        dev_set_uevent_suppress(&device->dev, false);
        kobject_uevent(&device->dev.kobj, KOBJ_ADD);
}

static int acpi_add_single_object(struct acpi_device **child,
                                  acpi_handle handle, int type,
                                  unsigned long long sta)
{
        int result;
        struct acpi_device *device;
        struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };

        device = kzalloc(sizeof(struct acpi_device), GFP_KERNEL);
        if (!device) {
                printk(KERN_ERR PREFIX "Memory allocation error\n");
                return -ENOMEM;
        }

        acpi_init_device_object(device, handle, type, sta);
        acpi_bus_get_power_flags(device);
        acpi_bus_get_wakeup_device_flags(device);

        result = acpi_device_add(device, acpi_device_release);
        if (result) {
                acpi_device_release(&device->dev);
                return result;
        }

        acpi_power_add_remove_device(device, true);
        acpi_device_add_finalize(device);
        acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
        ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Added %s [%s] parent %s\n",
                dev_name(&device->dev), (char *) buffer.pointer,
                device->parent ? dev_name(&device->parent->dev) : "(null)"));
        kfree(buffer.pointer);
        *child = device;
        return 0;
}

static int acpi_bus_type_and_status(acpi_handle handle, int *type,
                                    unsigned long long *sta)
{
        acpi_status status;
        acpi_object_type acpi_type;

        status = acpi_get_type(handle, &acpi_type);
        if (ACPI_FAILURE(status))
                return -ENODEV;

        switch (acpi_type) {
        case ACPI_TYPE_ANY:             /* for ACPI_ROOT_OBJECT */
        case ACPI_TYPE_DEVICE:
                *type = ACPI_BUS_TYPE_DEVICE;
                status = acpi_bus_get_status_handle(handle, sta);
                if (ACPI_FAILURE(status))
                        return -ENODEV;
                break;
        case ACPI_TYPE_PROCESSOR:
                *type = ACPI_BUS_TYPE_PROCESSOR;
                status = acpi_bus_get_status_handle(handle, sta);
                if (ACPI_FAILURE(status))
                        return -ENODEV;
                break;
        case ACPI_TYPE_THERMAL:
                *type = ACPI_BUS_TYPE_THERMAL;
                *sta = ACPI_STA_DEFAULT;
                break;
        case ACPI_TYPE_POWER:
                *type = ACPI_BUS_TYPE_POWER;
                *sta = ACPI_STA_DEFAULT;
                break;
        default:
                return -ENODEV;
        }

        return 0;
}

bool acpi_device_is_present(struct acpi_device *adev)
{
        if (adev->status.present || adev->status.functional)
                return true;

        adev->flags.initialized = false;
        return false;
}

static bool acpi_scan_handler_matching(struct acpi_scan_handler *handler,
                                       char *idstr,
                                       const struct acpi_device_id **matchid)
{
        const struct acpi_device_id *devid;

        if (handler->match)
                return handler->match(idstr, matchid);

        for (devid = handler->ids; devid->id[0]; devid++)
                if (!strcmp((char *)devid->id, idstr)) {
                        if (matchid)
                                *matchid = devid;

                        return true;
                }

        return false;
}

static struct acpi_scan_handler *acpi_scan_match_handler(char *idstr,
                                        const struct acpi_device_id **matchid)
{
        struct acpi_scan_handler *handler;

        list_for_each_entry(handler, &acpi_scan_handlers_list, list_node)
                if (acpi_scan_handler_matching(handler, idstr, matchid))
                        return handler;

        return NULL;
}

void acpi_scan_hotplug_enabled(struct acpi_hotplug_profile *hotplug, bool val)
{
        if (!!hotplug->enabled == !!val)
                return;

        mutex_lock(&acpi_scan_lock);

        hotplug->enabled = val;

        mutex_unlock(&acpi_scan_lock);
}

static void acpi_scan_init_hotplug(struct acpi_device *adev)
{
        struct acpi_hardware_id *hwid;

        if (acpi_dock_match(adev->handle) || is_ejectable_bay(adev)) {
                acpi_dock_add(adev);
                return;
        }
        list_for_each_entry(hwid, &adev->pnp.ids, list) {
                struct acpi_scan_handler *handler;

                handler = acpi_scan_match_handler(hwid->id, NULL);
                if (handler) {
                        adev->flags.hotplug_notify = true;
                        break;
                }
        }
}

static void acpi_device_dep_initialize(struct acpi_device *adev)
{
        struct acpi_dep_data *dep;
        struct acpi_handle_list dep_devices;
        acpi_status status;
        int i;

        if (!acpi_has_method(adev->handle, "_DEP"))
                return;

        status = acpi_evaluate_reference(adev->handle, "_DEP", NULL,
                                        &dep_devices);
        if (ACPI_FAILURE(status)) {
                dev_dbg(&adev->dev, "Failed to evaluate _DEP.\n");
                return;
        }

        for (i = 0; i < dep_devices.count; i++) {
                struct acpi_device_info *info;
                int skip;

                status = acpi_get_object_info(dep_devices.handles[i], &info);
                if (ACPI_FAILURE(status)) {
                        dev_dbg(&adev->dev, "Error reading _DEP device info\n");
                        continue;
                }

                /*
                 * Skip the dependency of Windows System Power
                 * Management Controller
                 */
                skip = info->valid & ACPI_VALID_HID &&
                        !strcmp(info->hardware_id.string, "INT3396");

                kfree(info);

                if (skip)
                        continue;

                dep = kzalloc(sizeof(struct acpi_dep_data), GFP_KERNEL);
                if (!dep)
                        return;

                dep->master = dep_devices.handles[i];
                dep->slave  = adev->handle;
                adev->dep_unmet++;

                mutex_lock(&acpi_dep_list_lock);
                list_add_tail(&dep->node , &acpi_dep_list);
                mutex_unlock(&acpi_dep_list_lock);
        }
}

static acpi_status acpi_bus_check_add(acpi_handle handle, u32 lvl_not_used,
                                      void *not_used, void **return_value)
{
        struct acpi_device *device = NULL;
        int type;
        unsigned long long sta;
        int result;

        acpi_bus_get_device(handle, &device);
        if (device)
                goto out;

        result = acpi_bus_type_and_status(handle, &type, &sta);
        if (result)
                return AE_OK;

        if (type == ACPI_BUS_TYPE_POWER) {
                acpi_add_power_resource(handle);
                return AE_OK;
        }

        acpi_add_single_object(&device, handle, type, sta);
        if (!device)
                return AE_CTRL_DEPTH;

        acpi_scan_init_hotplug(device);
        acpi_device_dep_initialize(device);

 out:
        if (!*return_value)
                *return_value = device;

        return AE_OK;
}

static int acpi_check_spi_i2c_slave(struct acpi_resource *ares, void *data)
{
        bool *is_spi_i2c_slave_p = data;

        if (ares->type != ACPI_RESOURCE_TYPE_SERIAL_BUS)
                return 1;

        /*
         * devices that are connected to UART still need to be enumerated to
         * platform bus
         */
        if (ares->data.common_serial_bus.type != ACPI_RESOURCE_SERIAL_TYPE_UART)
                *is_spi_i2c_slave_p = true;

         /* no need to do more checking */
        return -1;
}

static void acpi_default_enumeration(struct acpi_device *device)
{
        struct list_head resource_list;
        bool is_spi_i2c_slave = false;

        /*
         * Do not enemerate SPI/I2C slaves as they will be enuerated by their
         * respective parents.
         */
        INIT_LIST_HEAD(&resource_list);
        acpi_dev_get_resources(device, &resource_list, acpi_check_spi_i2c_slave,
                               &is_spi_i2c_slave);
        acpi_dev_free_resource_list(&resource_list);
        if (!is_spi_i2c_slave)
                acpi_create_platform_device(device);
}

static const struct acpi_device_id generic_device_ids[] = {
        {"PRP0001", },
        {"", },
};

static int acpi_generic_device_attach(struct acpi_device *adev,
                                      const struct acpi_device_id *not_used)
{
        /*
         * Since PRP0001 is the only ID handled here, the test below can be
         * unconditional.
         */
        if (adev->data.of_compatible)
                acpi_default_enumeration(adev);

        return 1;
}

static struct acpi_scan_handler generic_device_handler = {
        .ids = generic_device_ids,
        .attach = acpi_generic_device_attach,
};

static int acpi_scan_attach_handler(struct acpi_device *device)
{
        struct acpi_hardware_id *hwid;
        int ret = 0;

        list_for_each_entry(hwid, &device->pnp.ids, list) {
                const struct acpi_device_id *devid;
                struct acpi_scan_handler *handler;

                handler = acpi_scan_match_handler(hwid->id, &devid);
                if (handler) {
                        if (!handler->attach) {
                                device->pnp.type.platform_id = 0;
                                continue;
                        }
                        device->handler = handler;
                        ret = handler->attach(device, devid);
                        if (ret > 0)
                                break;

                        device->handler = NULL;
                        if (ret < 0)
                                break;
                }
        }

        return ret;
}

static void acpi_bus_attach(struct acpi_device *device)
{
        struct acpi_device *child;
        acpi_handle ejd;
        int ret;

        if (ACPI_SUCCESS(acpi_bus_get_ejd(device->handle, &ejd)))
                register_dock_dependent_device(device, ejd);

        acpi_bus_get_status(device);
        /* Skip devices that are not present. */
        if (!acpi_device_is_present(device)) {
                device->flags.visited = false;
                device->flags.power_manageable = 0;
                return;
        }
        if (device->handler)
                goto ok;

        if (!device->flags.initialized) {
                device->flags.power_manageable =
                        device->power.states[ACPI_STATE_D0].flags.valid;
                if (acpi_bus_init_power(device))
                        device->flags.power_manageable = 0;

                device->flags.initialized = true;
        }
        device->flags.visited = false;
        ret = acpi_scan_attach_handler(device);
        if (ret < 0)
                return;

        device->flags.match_driver = true;
        if (!ret) {
                ret = device_attach(&device->dev);
                if (ret < 0)
                        return;

                if (!ret && device->pnp.type.platform_id)
                        acpi_default_enumeration(device);
        }
        device->flags.visited = true;

 ok:
        list_for_each_entry(child, &device->children, node)
                acpi_bus_attach(child);

        if (device->handler && device->handler->hotplug.notify_online)
                device->handler->hotplug.notify_online(device);
}

void acpi_walk_dep_device_list(acpi_handle handle)
{
        struct acpi_dep_data *dep, *tmp;
        struct acpi_device *adev;

        mutex_lock(&acpi_dep_list_lock);
        list_for_each_entry_safe(dep, tmp, &acpi_dep_list, node) {
                if (dep->master == handle) {
                        acpi_bus_get_device(dep->slave, &adev);
                        if (!adev)
                                continue;

                        adev->dep_unmet--;
                        if (!adev->dep_unmet)
                                acpi_bus_attach(adev);
                        list_del(&dep->node);
                        kfree(dep);
                }
        }
        mutex_unlock(&acpi_dep_list_lock);
}
EXPORT_SYMBOL_GPL(acpi_walk_dep_device_list);

/**
 * acpi_bus_scan - Add ACPI device node objects in a given namespace scope.
 * @handle: Root of the namespace scope to scan.
 *
 * Scan a given ACPI tree (probably recently hot-plugged) and create and add
 * found devices.
 *
 * If no devices were found, -ENODEV is returned, but it does not mean that
 * there has been a real error.  There just have been no suitable ACPI objects
 * in the table trunk from which the kernel could create a device and add an
 * appropriate driver.
 *
 * Must be called under acpi_scan_lock.
 */
int acpi_bus_scan(acpi_handle handle)
{
        void *device = NULL;

        if (ACPI_SUCCESS(acpi_bus_check_add(handle, 0, NULL, &device)))
                acpi_walk_namespace(ACPI_TYPE_ANY, handle, ACPI_UINT32_MAX,
                                    acpi_bus_check_add, NULL, NULL, &device);

        if (device) {
                acpi_bus_attach(device);
                return 0;
        }
        return -ENODEV;
}
EXPORT_SYMBOL(acpi_bus_scan);

/**
 * acpi_bus_trim - Detach scan handlers and drivers from ACPI device objects.
 * @adev: Root of the ACPI namespace scope to walk.
 *
 * Must be called under acpi_scan_lock.
 */
void acpi_bus_trim(struct acpi_device *adev)
{
        struct acpi_scan_handler *handler = adev->handler;
        struct acpi_device *child;

        list_for_each_entry_reverse(child, &adev->children, node)
                acpi_bus_trim(child);

        adev->flags.match_driver = false;
        if (handler) {
                if (handler->detach)
                        handler->detach(adev);

                adev->handler = NULL;
        } else {
                device_release_driver(&adev->dev);
        }
        /*
         * Most likely, the device is going away, so put it into D3cold before
         * that.
         */
        acpi_device_set_power(adev, ACPI_STATE_D3_COLD);
        adev->flags.initialized = false;
        adev->flags.visited = false;
}
EXPORT_SYMBOL_GPL(acpi_bus_trim);

static int acpi_bus_scan_fixed(void)
{
        int result = 0;

        /*
         * Enumerate all fixed-feature devices.
         */
        if (!(acpi_gbl_FADT.flags & ACPI_FADT_POWER_BUTTON)) {
                struct acpi_device *device = NULL;

                result = acpi_add_single_object(&device, NULL,
                                                ACPI_BUS_TYPE_POWER_BUTTON,
                                                ACPI_STA_DEFAULT);
                if (result)
                        return result;

                device->flags.match_driver = true;
                result = device_attach(&device->dev);
                if (result < 0)
                        return result;

                device_init_wakeup(&device->dev, true);
        }

        if (!(acpi_gbl_FADT.flags & ACPI_FADT_SLEEP_BUTTON)) {
                struct acpi_device *device = NULL;

                result = acpi_add_single_object(&device, NULL,
                                                ACPI_BUS_TYPE_SLEEP_BUTTON,
                                                ACPI_STA_DEFAULT);
                if (result)
                        return result;

                device->flags.match_driver = true;
                result = device_attach(&device->dev);
        }

        return result < 0 ? result : 0;
}

int __init acpi_scan_init(void)
{
        int result;

        result = bus_register(&acpi_bus_type);
        if (result) {
                /* We don't want to quit even if we failed to add suspend/resume */
                printk(KERN_ERR PREFIX "Could not register bus type\n");
        }

        acpi_pci_root_init();
        acpi_pci_link_init();
        acpi_processor_init();
        acpi_lpss_init();
        acpi_apd_init();
        acpi_cmos_rtc_init();
        acpi_container_init();
        acpi_memory_hotplug_init();
        acpi_pnp_init();
        acpi_int340x_thermal_init();

        acpi_scan_add_handler(&generic_device_handler);

        mutex_lock(&acpi_scan_lock);
        /*
         * Enumerate devices in the ACPI namespace.
         */
        result = acpi_bus_scan(ACPI_ROOT_OBJECT);
        if (result)
                goto out;

        result = acpi_bus_get_device(ACPI_ROOT_OBJECT, &acpi_root);
        if (result)
                goto out;

        /* Fixed feature devices do not exist on HW-reduced platform */
        if (!acpi_gbl_reduced_hardware) {
                result = acpi_bus_scan_fixed();
                if (result) {
                        acpi_detach_data(acpi_root->handle,
                                         acpi_scan_drop_device);
                        acpi_device_del(acpi_root);
                        put_device(&acpi_root->dev);
                        goto out;
                }
        }

        acpi_update_all_gpes();

 out:
        mutex_unlock(&acpi_scan_lock);
        return result;
}