Merge with Linux 2.5.56.

[linux-2.6/linux-mips.git] / drivers / acpi / scan.c

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

#include <linux/init.h>
#include <linux/acpi.h>

#include "acpi_drivers.h"
#include "include/acinterp.h"   /* for acpi_ex_eisa_id_to_string() */


#define _COMPONENT              ACPI_BUS_COMPONENT
ACPI_MODULE_NAME                ("scan")

#define STRUCT_TO_INT(s)        (*((int*)&s))

extern struct acpi_device               *acpi_root;


#define ACPI_BUS_CLASS                  "system_bus"
#define ACPI_BUS_HID                    "ACPI_BUS"
#define ACPI_BUS_DRIVER_NAME            "ACPI Bus Driver"
#define ACPI_BUS_DEVICE_NAME            "System Bus"

static LIST_HEAD(acpi_device_list);
static spinlock_t acpi_device_lock = SPIN_LOCK_UNLOCKED;

static void acpi_device_release(struct kobject * kobj)
{
        struct acpi_device * dev = container_of(kobj,struct acpi_device,kobj);
        kfree(dev);
}

static struct kobj_type ktype_acpi_ns = {
        .release        = acpi_device_release,
};

static struct kset acpi_namespace_kset = {
        .kobj           = { 
                .name = "namespace",
        },
        .subsys = &acpi_subsys,
        .ktype  = &ktype_acpi_ns,
};


static void acpi_device_register(struct acpi_device * device, struct acpi_device * parent)
{
        /*
         * Linkage
         * -------
         * Link this device to its parent and siblings.
         */
        INIT_LIST_HEAD(&device->children);
        INIT_LIST_HEAD(&device->node);
        INIT_LIST_HEAD(&device->g_list);

        spin_lock(&acpi_device_lock);
        if (device->parent) {
                list_add_tail(&device->node, &device->parent->children);
                list_add_tail(&device->g_list,&device->parent->g_list);
        } else
                list_add_tail(&device->g_list,&acpi_device_list);
        spin_unlock(&acpi_device_lock);

        kobject_init(&device->kobj);
        strncpy(device->kobj.name,device->pnp.bus_id,KOBJ_NAME_LEN);
        if (parent)
                device->kobj.parent = &parent->kobj;
        device->kobj.ktype = &ktype_acpi_ns;
        device->kobj.kset = &acpi_namespace_kset;
        kobject_register(&device->kobj);
}

static int
acpi_device_unregister (
        struct acpi_device      *device, 
        int                     type)
{
        kobject_unregister(&device->kobj);
        return 0;
}

void
acpi_bus_data_handler (
        acpi_handle             handle,
        u32                     function,
        void                    *context)
{
        ACPI_FUNCTION_TRACE("acpi_bus_data_handler");

        /* TBD */

        return_VOID;
}

static int
acpi_bus_get_power_flags (
        struct acpi_device      *device)
{
        acpi_status             status = 0;
        acpi_handle             handle = 0;
        u32                     i = 0;

        ACPI_FUNCTION_TRACE("acpi_bus_get_power_flags");

        /*
         * Power Management Flags
         */
        status = acpi_get_handle(device->handle, "_PSC", &handle);
        if (ACPI_SUCCESS(status))
                device->power.flags.explicit_get = 1;
        status = acpi_get_handle(device->handle, "_IRC", &handle);
        if (ACPI_SUCCESS(status))
                device->power.flags.inrush_current = 1;
        status = acpi_get_handle(device->handle, "_PRW", &handle);
        if (ACPI_SUCCESS(status))
                device->power.flags.wake_capable = 1;

        /*
         * Enumerate supported power management states
         */
        for (i = ACPI_STATE_D0; i <= ACPI_STATE_D3; i++) {
                struct acpi_device_power_state *ps = &device->power.states[i];
                char            object_name[5] = {'_','P','R','0'+i,'\0'};

                /* Evaluate "_PRx" to se if power resources are referenced */
                acpi_evaluate_reference(device->handle, object_name, NULL,
                        &ps->resources);
                if (ps->resources.count) {
                        device->power.flags.power_resources = 1;
                        ps->flags.valid = 1;
                }

                /* Evaluate "_PSx" to see if we can do explicit sets */
                object_name[2] = 'S';
                status = acpi_get_handle(device->handle, object_name, &handle);
                if (ACPI_SUCCESS(status)) {
                        ps->flags.explicit_set = 1;
                        ps->flags.valid = 1;
                }

                /* State is valid if we have some power control */
                if (ps->resources.count || ps->flags.explicit_set)
                        ps->flags.valid = 1;

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

        /* 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].flags.valid = 1;
        device->power.states[ACPI_STATE_D3].power = 0;

        /* TBD: System wake support and resource requirements. */

        device->power.state = ACPI_STATE_UNKNOWN;

        return 0;
}


/* --------------------------------------------------------------------------
                              Performance Management
   -------------------------------------------------------------------------- */

static int
acpi_bus_get_perf_flags (
        struct acpi_device      *device)
{
        device->performance.state = ACPI_STATE_UNKNOWN;
        return 0;
}

/* --------------------------------------------------------------------------
                                 Driver Management
   -------------------------------------------------------------------------- */

static LIST_HEAD(acpi_bus_drivers);
static DECLARE_MUTEX(acpi_bus_drivers_lock);


/**
 * acpi_bus_match 
 * --------------
 * Checks the device's hardware (_HID) or compatible (_CID) ids to see if it
 * matches the specified driver's criteria.
 */
static int
acpi_bus_match (
        struct acpi_device      *device,
        struct acpi_driver      *driver)
{
        int error = 0;
        struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};

        if (device->flags.hardware_id)
                if (strstr(driver->ids, device->pnp.hardware_id))
                        goto Done;

        if (device->flags.compatible_ids) {
                acpi_status             status = AE_OK;
                union acpi_object       *object = NULL;
                char                    cid[256] = {};

                status = acpi_evaluate_object(device->handle, "_CID", NULL, 
                        &buffer);
                if (ACPI_FAILURE(status) || !buffer.pointer)
                        return -ENOENT;

                object = (union acpi_object *) buffer.pointer;

                switch (object->type) {
                case ACPI_TYPE_INTEGER:
                        acpi_ex_eisa_id_to_string((u32) object->integer.value, 
                                cid);
                        break;
                case ACPI_TYPE_STRING:
                        strncpy(cid, object->string.pointer, sizeof(cid) - 1);
                        break;
                case ACPI_TYPE_PACKAGE:
                        /* TBD: Support CID packages */
                        break;
                }

                if (strlen(cid) && strstr(driver->ids,cid))
                        goto Done;
        }
        error = -ENOENT;

 Done:
        if (buffer.pointer)
                acpi_os_free(buffer.pointer);
        return error;
}


/**
 * acpi_bus_driver_init 
 * --------------------
 * Used to initialize a device via its device driver.  Called whenever a 
 * driver is bound to a device.  Invokes the driver's add() and start() ops.
 */
static int
acpi_bus_driver_init (
        struct acpi_device      *device, 
        struct acpi_driver      *driver)
{
        int                     result = 0;

        ACPI_FUNCTION_TRACE("acpi_bus_driver_init");

        if (!device || !driver)
                return_VALUE(-EINVAL);

        if (!driver->ops.add)
                return_VALUE(-ENOSYS);

        result = driver->ops.add(device);
        if (result) {
                device->driver = NULL;
                acpi_driver_data(device) = NULL;
                return_VALUE(result);
        }

        device->driver = driver;

        /*
         * TBD - Configuration Management: Assign resources to device based
         * upon possible configuration and currently allocated resources.
         */

        if (driver->ops.start) {
                result = driver->ops.start(device);
                if (result && driver->ops.remove)
                        driver->ops.remove(device, ACPI_BUS_REMOVAL_NORMAL);
                return_VALUE(result);
        }

        ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Driver successfully bound to device\n"));

        if (driver->ops.scan) {
                driver->ops.scan(device);
        }

        return_VALUE(0);
}

static int acpi_driver_attach(struct acpi_driver * drv)
{
        struct list_head * node, * next;

        ACPI_FUNCTION_TRACE("acpi_driver_attach");

        spin_lock(&acpi_device_lock);
        list_for_each_safe(node,next,&acpi_device_list) {
                struct acpi_device * dev = container_of(node,struct acpi_device,g_list);

                if (dev->driver || !dev->status.present)
                        continue;
                spin_unlock(&acpi_device_lock);

                if (!acpi_bus_match(dev,drv)) {
                        if (!acpi_bus_driver_init(dev,drv)) {
                                atomic_inc(&drv->references);
                                ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found driver [%s] for device [%s]\n",
                                                  drv->name, dev->pnp.bus_id));
                        }
                }
                spin_lock(&acpi_device_lock);
        }
        spin_unlock(&acpi_device_lock);
        return_VALUE(0);
}

static int acpi_driver_detach(struct acpi_driver * drv)
{
        struct list_head * node, * next;

        ACPI_FUNCTION_TRACE("acpi_driver_detach");

        spin_lock(&acpi_device_lock);
        list_for_each_safe(node,next,&acpi_device_list) {
                struct acpi_device * dev = container_of(node,struct acpi_device,g_list);

                if (dev->driver == drv) {
                        if (drv->ops.remove)
                                drv->ops.remove(dev,ACPI_BUS_REMOVAL_NORMAL);
                        dev->driver = NULL;
                        dev->driver_data = NULL;
                        atomic_dec(&drv->references);
                }
        }
        spin_unlock(&acpi_device_lock);
        return_VALUE(0);
}

/**
 * acpi_bus_register_driver 
 * ------------------------ 
 * Registers a driver with the ACPI bus.  Searches the namespace for all
 * devices that match the driver's criteria and binds.
 */
int
acpi_bus_register_driver (
        struct acpi_driver      *driver)
{
        int error = 0;

        ACPI_FUNCTION_TRACE("acpi_bus_register_driver");

        if (driver) {
                spin_lock(&acpi_device_lock);
                list_add_tail(&driver->node, &acpi_bus_drivers);
                spin_unlock(&acpi_device_lock);
                acpi_driver_attach(driver);
        } else
                error = -EINVAL;

        return_VALUE(error);
}


/**
 * acpi_bus_unregister_driver 
 * --------------------------
 * Unregisters a driver with the ACPI bus.  Searches the namespace for all
 * devices that match the driver's criteria and unbinds.
 */
int
acpi_bus_unregister_driver (
        struct acpi_driver      *driver)
{
        int error = 0;

        ACPI_FUNCTION_TRACE("acpi_bus_unregister_driver");

        if (driver) {
                acpi_driver_detach(driver);

                if (!atomic_read(&driver->references)) {
                        spin_lock(&acpi_device_lock);
                        list_del_init(&driver->node);
                        spin_unlock(&acpi_device_lock);
                } 
        } else 
                error = -EINVAL;
        return_VALUE(error);
}

/**
 * acpi_bus_find_driver 
 * --------------------
 * Parses the list of registered drivers looking for a driver applicable for
 * the specified device.
 */
static int
acpi_bus_find_driver (
        struct acpi_device      *device)
{
        int                     result = 0;
        struct list_head        * node, *next;

        ACPI_FUNCTION_TRACE("acpi_bus_find_driver");

        if (!device->flags.hardware_id && !device->flags.compatible_ids)
                goto Done;

        spin_lock(&acpi_device_lock);
        list_for_each_safe(node,next,&acpi_bus_drivers) {
                struct acpi_driver * driver = container_of(node,struct acpi_driver,node);

                atomic_inc(&driver->references);
                spin_unlock(&acpi_device_lock);
                if (!acpi_bus_match(device, driver)) {
                        result = acpi_bus_driver_init(device, driver);
                        if (!result)
                                goto Done;
                }
                atomic_dec(&driver->references);
                spin_lock(&acpi_device_lock);
        }
        spin_unlock(&acpi_device_lock);

 Done:
        return_VALUE(result);
}


/* --------------------------------------------------------------------------
                                 Device Enumeration
   -------------------------------------------------------------------------- */

static int 
acpi_bus_get_flags (
        struct acpi_device      *device)
{
        acpi_status             status = AE_OK;
        acpi_handle             temp = NULL;

        ACPI_FUNCTION_TRACE("acpi_bus_get_flags");

        /* Presence of _STA indicates 'dynamic_status' */
        status = acpi_get_handle(device->handle, "_STA", &temp);
        if (ACPI_SUCCESS(status))
                device->flags.dynamic_status = 1;

        /* Presence of _CID indicates 'compatible_ids' */
        status = acpi_get_handle(device->handle, "_CID", &temp);
        if (ACPI_SUCCESS(status))
                device->flags.compatible_ids = 1;

        /* Presence of _RMV indicates 'removable' */
        status = acpi_get_handle(device->handle, "_RMV", &temp);
        if (ACPI_SUCCESS(status))
                device->flags.removable = 1;

        /* Presence of _EJD|_EJ0 indicates 'ejectable' */
        status = acpi_get_handle(device->handle, "_EJD", &temp);
        if (ACPI_SUCCESS(status))
                device->flags.ejectable = 1;
        else {
                status = acpi_get_handle(device->handle, "_EJ0", &temp);
                if (ACPI_SUCCESS(status))
                        device->flags.ejectable = 1;
        }

        /* Presence of _LCK indicates 'lockable' */
        status = acpi_get_handle(device->handle, "_LCK", &temp);
        if (ACPI_SUCCESS(status))
                device->flags.lockable = 1;

        /* Presence of _PS0|_PR0 indicates 'power manageable' */
        status = acpi_get_handle(device->handle, "_PS0", &temp);
        if (ACPI_FAILURE(status))
                status = acpi_get_handle(device->handle, "_PR0", &temp);
        if (ACPI_SUCCESS(status))
                device->flags.power_manageable = 1;

        /* TBD: Peformance management */

        return_VALUE(0);
}

static void acpi_device_get_busid(struct acpi_device * device, acpi_handle handle, int type)
{
        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)?
         */
        switch (type) {
        case ACPI_BUS_TYPE_SYSTEM:
                sprintf(device->pnp.bus_id, "%s", "ACPI");
                break;
        case ACPI_BUS_TYPE_POWER_BUTTON:
                sprintf(device->pnp.bus_id, "%s", "PWRF");
                break;
        case ACPI_BUS_TYPE_SLEEP_BUTTON:
                sprintf(device->pnp.bus_id, "%s", "SLPF");
                break;
        default:
                acpi_get_name(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;
                }
                sprintf(device->pnp.bus_id, "%s", bus_id);
                break;
        }
}

static void acpi_device_set_id(struct acpi_device * device, struct acpi_device * parent,
                               acpi_handle handle, int type)
{
        struct acpi_device_info info;
        char                    *hid = NULL;
        char                    *uid = NULL;
        acpi_status             status;

        switch (type) {
        case ACPI_BUS_TYPE_DEVICE:
                status = acpi_get_object_info(handle, &info);
                if (ACPI_FAILURE(status)) {
                        printk("%s: Error reading device info\n",__FUNCTION__);
                        return;
                }
                /* Clean up info strings (not NULL terminated) */
                info.hardware_id[sizeof(info.hardware_id)-1] = '\0';
                info.unique_id[sizeof(info.unique_id)-1] = '\0';
                if (info.valid & ACPI_VALID_HID)
                        hid = info.hardware_id;
                if (info.valid & ACPI_VALID_UID)
                        uid = info.unique_id;
                if (info.valid & ACPI_VALID_ADR) {
                        device->pnp.bus_address = info.address;
                        device->flags.bus_address = 1;
                }
                break;
        case ACPI_BUS_TYPE_POWER:
                hid = ACPI_POWER_HID;
                break;
        case ACPI_BUS_TYPE_PROCESSOR:
                hid = ACPI_PROCESSOR_HID;
                break;
        case ACPI_BUS_TYPE_SYSTEM:
                hid = ACPI_SYSTEM_HID;
                break;
        case ACPI_BUS_TYPE_THERMAL:
                hid = ACPI_THERMAL_HID;
                break;
        case ACPI_BUS_TYPE_POWER_BUTTON:
                hid = ACPI_BUTTON_HID_POWERF;
                break;
        case ACPI_BUS_TYPE_SLEEP_BUTTON:
                hid = ACPI_BUTTON_HID_SLEEPF;
                break;
        }

        /* 
         * \_SB
         * ----
         * Fix for the system root bus device -- the only root-level device.
         */
        if ((parent == ACPI_ROOT_OBJECT) && (type == ACPI_BUS_TYPE_DEVICE)) {
                hid = ACPI_BUS_HID;
                sprintf(device->pnp.device_name, "%s", ACPI_BUS_DEVICE_NAME);
                sprintf(device->pnp.device_class, "%s", ACPI_BUS_CLASS);
        }

        if (hid) {
                sprintf(device->pnp.hardware_id, "%s", hid);
                device->flags.hardware_id = 1;
        }
        if (uid) {
                sprintf(device->pnp.unique_id, "%s", uid);
                device->flags.unique_id = 1;
        }
}

int acpi_device_set_context(struct acpi_device * device, int type)
{
        acpi_status status = AE_OK;
        int result = 0;
        /*
         * Context
         * -------
         * Attach this 'struct acpi_device' to the ACPI object.  This makes
         * resolutions from handle->device very efficient.  Note that we need
         * to be careful with fixed-feature devices as they all attach to the
         * root object.
         */
        if (type != ACPI_BUS_TYPE_POWER_BUTTON && 
            type != ACPI_BUS_TYPE_SLEEP_BUTTON) {
                status = acpi_attach_data(device->handle,
                        acpi_bus_data_handler, device);

                if (ACPI_FAILURE(status)) {
                        printk("Error attaching device data\n");
                        result = -ENODEV;
                }
        }
        return result;
}

void acpi_device_get_debug_info(struct acpi_device * device, acpi_handle handle, int type)
{
#ifdef CONFIG_ACPI_DEBUG_OUTPUT
        char            *type_string = NULL;
        char            name[80] = {'?','\0'};
        acpi_buffer     buffer = {sizeof(name), name};

        switch (type) {
        case ACPI_BUS_TYPE_DEVICE:
                type_string = "Device";
                acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
                break;
        case ACPI_BUS_TYPE_POWER:
                type_string = "Power Resource";
                acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
                break;
        case ACPI_BUS_TYPE_PROCESSOR:
                type_string = "Processor";
                acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
                break;
        case ACPI_BUS_TYPE_SYSTEM:
                type_string = "System";
                acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
                break;
        case ACPI_BUS_TYPE_THERMAL:
                type_string = "Thermal Zone";
                acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
                break;
        case ACPI_BUS_TYPE_POWER_BUTTON:
                type_string = "Power Button";
                sprintf(name, "PWRB");
                break;
        case ACPI_BUS_TYPE_SLEEP_BUTTON:
                type_string = "Sleep Button";
                sprintf(name, "SLPB");
                break;
        }

        printk(KERN_DEBUG "Found %s %s [%p]\n", type_string, name, handle);
#endif /*CONFIG_ACPI_DEBUG_OUTPUT*/
}

static int 
acpi_bus_add (
        struct acpi_device      **child,
        struct acpi_device      *parent,
        acpi_handle             handle,
        int                     type)
{
        int                     result = 0;
        struct acpi_device      *device = NULL;

        ACPI_FUNCTION_TRACE("acpi_bus_add");

        if (!child)
                return_VALUE(-EINVAL);

        device = kmalloc(sizeof(struct acpi_device), GFP_KERNEL);
        if (!device) {
                ACPI_DEBUG_PRINT((ACPI_DB_ERROR, "Memory allocation error\n"));
                return_VALUE(-ENOMEM);
        }
        memset(device, 0, sizeof(struct acpi_device));

        device->handle = handle;
        device->parent = parent;

        acpi_device_get_busid(device,handle,type);

        /*
         * Flags
         * -----
         * Get prior to calling acpi_bus_get_status() so we know whether
         * or not _STA is present.  Note that we only look for object
         * handles -- cannot evaluate objects until we know the device is
         * present and properly initialized.
         */
        result = acpi_bus_get_flags(device);
        if (result)
                goto end;

        /*
         * Status
         * ------
         * See if the device is present.  We always assume that non-Device()
         * objects (e.g. thermal zones, power resources, processors, etc.) are
         * present, functioning, etc. (at least when parent object is present).
         * Note that _STA has a different meaning for some objects (e.g.
         * power resources) so we need to be careful how we use it.
         */
        switch (type) {
        case ACPI_BUS_TYPE_DEVICE:
                result = acpi_bus_get_status(device);
                if (!result)
                        break;
                if (!device->status.present) 
                        result = -ENOENT;
                goto end;
        default:
                STRUCT_TO_INT(device->status) = 0x0F;
                break;
        }

        /*
         * Initialize Device
         * -----------------
         * TBD: Synch with Core's enumeration/initialization process.
         */

        /*
         * Hardware ID, Unique ID, & Bus Address
         * -------------------------------------
         */
        acpi_device_set_id(device,parent,handle,type);

        /*
         * Power Management
         * ----------------
         */
        if (device->flags.power_manageable) {
                result = acpi_bus_get_power_flags(device);
                if (result)
                        goto end;
        }

        /*
         * Performance Management
         * ----------------------
         */
        if (device->flags.performance_manageable) {
                result = acpi_bus_get_perf_flags(device);
                if (result)
                        goto end;
        }

        if ((result = acpi_device_set_context(device,type)))
                goto end;

        acpi_device_get_debug_info(device,handle,type);

        acpi_device_register(device,parent);

        /*
         * Bind _ADR-Based Devices
         * -----------------------
         * If there's a a bus address (_ADR) then we utilize the parent's 
         * 'bind' function (if exists) to bind the ACPI- and natively-
         * enumerated device representations.
         */
        if (device->flags.bus_address) {
                if (device->parent && device->parent->ops.bind)
                        device->parent->ops.bind(device);
        }

        /*
         * Locate & Attach Driver
         * ----------------------
         * If there's a hardware id (_HID) or compatible ids (_CID) we check
         * to see if there's a driver installed for this kind of device.  Note
         * that drivers can install before or after a device is enumerated.
         *
         * TBD: Assumes LDM provides driver hot-plug capability.
         */
        acpi_bus_find_driver(device);

end:
        if (!result)
                *child = device;
        else
                kfree(device);
        return_VALUE(result);
}



static int acpi_bus_scan (struct acpi_device    *start)
{
        acpi_status             status = AE_OK;
        struct acpi_device      *parent = NULL;
        struct acpi_device      *child = NULL;
        acpi_handle             phandle = 0;
        acpi_handle             chandle = 0;
        acpi_object_type        type = 0;
        u32                     level = 1;

        ACPI_FUNCTION_TRACE("acpi_bus_scan");

        if (!start)
                return_VALUE(-EINVAL);

        parent = start;
        phandle = start->handle;
        
        /*
         * Parse through the ACPI namespace, identify all 'devices', and
         * create a new 'struct acpi_device' for each.
         */
        while ((level > 0) && parent) {

                status = acpi_get_next_object(ACPI_TYPE_ANY, phandle,
                        chandle, &chandle);

                /*
                 * If this scope is exhausted then move our way back up.
                 */
                if (ACPI_FAILURE(status)) {
                        level--;
                        chandle = phandle;
                        acpi_get_parent(phandle, &phandle);
                        if (parent->parent)
                                parent = parent->parent;
                        continue;
                }

                status = acpi_get_type(chandle, &type);
                if (ACPI_FAILURE(status))
                        continue;

                /*
                 * If this is a scope object then parse it (depth-first).
                 */
                if (type == ACPI_TYPE_LOCAL_SCOPE) {
                        level++;
                        phandle = chandle;
                        chandle = 0;
                        continue;
                }

                /*
                 * We're only interested in objects that we consider 'devices'.
                 */
                switch (type) {
                case ACPI_TYPE_DEVICE:
                        type = ACPI_BUS_TYPE_DEVICE;
                        break;
                case ACPI_TYPE_PROCESSOR:
                        type = ACPI_BUS_TYPE_PROCESSOR;
                        break;
                case ACPI_TYPE_THERMAL:
                        type = ACPI_BUS_TYPE_THERMAL;
                        break;
                case ACPI_TYPE_POWER:
                        type = ACPI_BUS_TYPE_POWER;
                        break;
                default:
                        continue;
                }

                status = acpi_bus_add(&child, parent, chandle, type);
                if (ACPI_FAILURE(status))
                        continue;

                /*
                 * If the device is present, enabled, and functioning then
                 * parse its scope (depth-first).  Note that we need to
                 * represent absent devices to facilitate PnP notifications
                 * -- but only the subtree head (not all of its children,
                 * which will be enumerated when the parent is inserted).
                 *
                 * TBD: Need notifications and other detection mechanisms
                 *      in place before we can fully implement this.
                 */
                if (child->status.present) {
                        status = acpi_get_next_object(ACPI_TYPE_ANY, chandle,
                                0, NULL);
                        if (ACPI_SUCCESS(status)) {
                                level++;
                                phandle = chandle;
                                chandle = 0;
                                parent = child;
                        }
                }
        }

        return_VALUE(0);
}


static int
acpi_bus_scan_fixed (
        struct acpi_device      *root)
{
        int                     result = 0;
        struct acpi_device      *device = NULL;

        ACPI_FUNCTION_TRACE("acpi_bus_scan_fixed");

        if (!root)
                return_VALUE(-ENODEV);

        /*
         * Enumerate all fixed-feature devices.
         */
        if (acpi_fadt.pwr_button == 0)
                result = acpi_bus_add(&device, acpi_root, 
                        NULL, ACPI_BUS_TYPE_POWER_BUTTON);

        if (acpi_fadt.sleep_button == 0)
                result = acpi_bus_add(&device, acpi_root, 
                        NULL, ACPI_BUS_TYPE_SLEEP_BUTTON);

        return_VALUE(result);
}


static int __init acpi_scan_init(void)
{
        int result;

        ACPI_FUNCTION_TRACE("acpi_scan_init");

        if (acpi_disabled)
                return_VALUE(0);

        kset_register(&acpi_namespace_kset);

        /*
         * Create the root device in the bus's device tree
         */
        result = acpi_bus_add(&acpi_root, NULL, ACPI_ROOT_OBJECT, 
                ACPI_BUS_TYPE_SYSTEM);
        if (result)
                goto Done;

        /*
         * Enumerate devices in the ACPI namespace.
         */
        result = acpi_bus_scan_fixed(acpi_root);
        if (!result) 
                result = acpi_bus_scan(acpi_root);

        if (result)
                acpi_device_unregister(acpi_root, ACPI_BUS_REMOVAL_NORMAL);

 Done:
        return_VALUE(result);
}

subsys_initcall(acpi_scan_init);