scan.c

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		hid = ACPI_BUTTON_HID_SLEEPF;
		break;
	}

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

	if (hid) {
		strcpy(device->pnp.hardware_id, hid);
		device->flags.hardware_id = 1;
	}
	if (uid) {
		strcpy(device->pnp.unique_id, uid);
		device->flags.unique_id = 1;
	}
	if (cid_list) {
		device->pnp.cid_list = kmalloc(cid_list->size, GFP_KERNEL);
		if (device->pnp.cid_list)
			memcpy(device->pnp.cid_list, cid_list, cid_list->size);
		else
			printk(KERN_ERR "Memory allocation error\n");
	}

	kfree(buffer.pointer);
}

static 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;
}

static int acpi_bus_remove(struct acpi_device *dev, int rmdevice)
{
	if (!dev)
		return -EINVAL;

	dev->removal_type = ACPI_BUS_REMOVAL_EJECT;
	device_release_driver(&dev->dev);

	if (!rmdevice)
		return 0;

	/*
	 * unbind _ADR-Based Devices when hot removal
	 */
	if (dev->flags.bus_address) {
		if ((dev->parent) && (dev->parent->ops.unbind))
			dev->parent->ops.unbind(dev);
	}
	acpi_device_unregister(dev, ACPI_BUS_REMOVAL_EJECT);

	return 0;
}

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


	if (!child)
		return -EINVAL;

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

	device->handle = handle;
	device->parent = parent;
	device->bus_ops = *ops; /* workround for not call .start */


	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
	 * and non-Processor objects (e.g. thermal zones, power resources,
	 * 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_PROCESSOR:
	case ACPI_BUS_TYPE_DEVICE:
		result = acpi_bus_get_status(device);
		if (ACPI_FAILURE(result) || !device->status.present) {
			result = -ENOENT;
			goto end;
		}
		break;
	default:
		STRUCT_TO_INT(device->status) =
		    ACPI_STA_DEVICE_PRESENT | ACPI_STA_DEVICE_ENABLED |
		    ACPI_STA_DEVICE_UI      | ACPI_STA_DEVICE_FUNCTIONING;
		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;
	}

	/*
	 * Wakeup device management
	 *-----------------------
	 */
	if (device->flags.wake_capable) {
		result = acpi_bus_get_wakeup_device_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;

	result = acpi_device_register(device, parent);

	/*
	 * Bind _ADR-Based Devices when hot add
	 */
	if (device->flags.bus_address) {
		if (device->parent && device->parent->ops.bind)
			device->parent->ops.bind(device);
	}

      end:
	if (!result)
		*child = device;
	else {
		kfree(device->pnp.cid_list);
		kfree(device);
	}

	return result;
}

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


	if (!start)
		return -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 = NULL;
			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;
		}

		if (ops->acpi_op_add)
			status = acpi_add_single_object(&child, parent,
				chandle, type, ops);
		else
			status = acpi_bus_get_device(chandle, &child);

		if (ACPI_FAILURE(status))
			continue;

		if (ops->acpi_op_start && !(ops->acpi_op_add)) {
			status = acpi_start_single_object(child);
			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,
						      NULL, NULL);
			if (ACPI_SUCCESS(status)) {
				level++;
				phandle = chandle;
				chandle = NULL;
				parent = child;
			}
		}
	}

	return 0;
}

int
acpi_bus_add(struct acpi_device **child,
	     struct acpi_device *parent, acpi_handle handle, int type)
{
	int result;
	struct acpi_bus_ops ops;

	memset(&ops, 0, sizeof(ops));
	ops.acpi_op_add = 1;

	result = acpi_add_single_object(child, parent, handle, type, &ops);
	if (!result)
		result = acpi_bus_scan(*child, &ops);

	return result;
}

EXPORT_SYMBOL(acpi_bus_add);

int acpi_bus_start(struct acpi_device *device)
{
	int result;
	struct acpi_bus_ops ops;


	if (!device)
		return -EINVAL;

	result = acpi_start_single_object(device);
	if (!result) {
		memset(&ops, 0, sizeof(ops));
		ops.acpi_op_start = 1;
		result = acpi_bus_scan(device, &ops);
	}
	return result;
}

EXPORT_SYMBOL(acpi_bus_start);

int acpi_bus_trim(struct acpi_device *start, int rmdevice)
{
	acpi_status status;
	struct acpi_device *parent, *child;
	acpi_handle phandle, chandle;
	acpi_object_type type;
	u32 level = 1;
	int err = 0;

	parent = start;
	phandle = start->handle;
	child = chandle = NULL;

	while ((level > 0) && parent && (!err)) {
		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);
			child = parent;
			parent = parent->parent;

			if (level == 0)
				err = acpi_bus_remove(child, rmdevice);
			else
				err = acpi_bus_remove(child, 1);

			continue;
		}

		status = acpi_get_type(chandle, &type);
		if (ACPI_FAILURE(status)) {
			continue;
		}
		/*
		 * If there is a device corresponding to chandle then
		 * parse it (depth-first).
		 */
		if (acpi_bus_get_device(chandle, &child) == 0) {
			level++;
			phandle = chandle;
			chandle = NULL;
			parent = child;
		}
		continue;
	}
	return err;
}
EXPORT_SYMBOL_GPL(acpi_bus_trim);


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

	if (!root)
		return -ENODEV;

	memset(&ops, 0, sizeof(ops));
	ops.acpi_op_add = 1;
	ops.acpi_op_start = 1;

	/*
	 * Enumerate all fixed-feature devices.
	 */
	if ((acpi_gbl_FADT.flags & ACPI_FADT_POWER_BUTTON) == 0) {
		result = acpi_add_single_object(&device, acpi_root,
						NULL,
						ACPI_BUS_TYPE_POWER_BUTTON,
						&ops);
	}

	if ((acpi_gbl_FADT.flags & ACPI_FADT_SLEEP_BUTTON) == 0) {
		result = acpi_add_single_object(&device, acpi_root,
						NULL,
						ACPI_BUS_TYPE_SLEEP_BUTTON,
						&ops);
	}

	return result;
}

int __init acpi_boot_ec_enable(void);

static int __init acpi_scan_init(void)
{
	int result;
	struct acpi_bus_ops ops;


	if (acpi_disabled)
		return 0;

	memset(&ops, 0, sizeof(ops));
	ops.acpi_op_add = 1;
	ops.acpi_op_start = 1;

	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");
	}

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

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

	/* EC region might be needed at bus_scan, so enable it now */
	acpi_boot_ec_enable();

	if (!result)
		result = acpi_bus_scan(acpi_root, &ops);

	if (result)
		acpi_device_unregister(acpi_root, ACPI_BUS_REMOVAL_NORMAL);

      Done:
	return result;
}

subsys_initcall(acpi_scan_init);