ACPI / scan: Add bind/unbind callbacks to struct acpi_scan_handler

In some cases it may be necessary to perform certain setup/cleanup
operations on a device object representing a physical device after
it has been associated with an ACPI companion by acpi_bind_one() or
before disassociating it from that companion by acpi_unbind_one(),
respectively.  If there is a struct acpi_bus_type object for the
given device's bus type, the .setup()/.cleanup() callbacks from there
are executed for these purposes.  However, an analogous mechanism will
be necessary for devices whose bus types don't have corresponding
struct acpi_bus_type objects and that have specific ACPI scan handlers.

For those devices, add new .bind() and .unbind() callbacks to struct
acpi_scan_handler that will be executed by acpi_platform_notify()
right after the given device has been associated with an ACPI
comapnion and by acpi_platform_notify_remove() right before calling
acpi_unbind_one() for that device, respectively.

To make that work for scan handlers registering new devices in their
.attach() callbacks, modify acpi_scan_attach_handler() to set the
ACPI device object's handler field before calling .attach() from the
scan handler at hand.

This changeset includes a fix from Mika Westerberg.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/glue.c

@@ -287,6 +287,7 @@ EXPORT_SYMBOL_GPL(acpi_unbind_one);
 static int acpi_platform_notify(struct device *dev)
 {
 	struct acpi_bus_type *type = acpi_get_bus_type(dev);
+	struct acpi_device *adev;
 	int ret;
 
 	ret = acpi_bind_one(dev, NULL);
@@ -303,9 +304,14 @@ static int acpi_platform_notify(struct device *dev)
 		if (ret)
 			goto out;
 	}
+	adev = ACPI_COMPANION(dev);
+	if (!adev)
+		goto out;
 
 	if (type && type->setup)
 		type->setup(dev);
+	else if (adev->handler && adev->handler->bind)
+		adev->handler->bind(dev);
 
  out:
 #if ACPI_GLUE_DEBUG
@@ -324,11 +330,17 @@ static int acpi_platform_notify(struct device *dev)
 
 static int acpi_platform_notify_remove(struct device *dev)
 {
+	struct acpi_device *adev = ACPI_COMPANION(dev);
 	struct acpi_bus_type *type;
 
+	if (!adev)
+		return 0;
+
 	type = acpi_get_bus_type(dev);
 	if (type && type->cleanup)
 		type->cleanup(dev);
+	else if (adev->handler && adev->handler->unbind)
+		adev->handler->unbind(dev);
 
 	acpi_unbind_one(dev);
 	return 0;

drivers/acpi/scan.c

@@ -2015,13 +2015,14 @@ static int acpi_scan_attach_handler(struct acpi_device *device)
 
 		handler = acpi_scan_match_handler(hwid->id, &devid);
 		if (handler) {
+			device->handler = handler;
 			ret = handler->attach(device, devid);
-			if (ret > 0) {
-				device->handler = handler;
+			if (ret > 0)
 				break;
-			} else if (ret < 0) {
+
+			device->handler = NULL;
+			if (ret < 0)
 				break;
-			}
 		}
 	}
 	return ret;

include/acpi/acpi_bus.h

@@ -133,6 +133,8 @@ struct acpi_scan_handler {
 	struct list_head list_node;
 	int (*attach)(struct acpi_device *dev, const struct acpi_device_id *id);
 	void (*detach)(struct acpi_device *dev);
+	void (*bind)(struct device *phys_dev);
+	void (*unbind)(struct device *phys_dev);
 	struct acpi_hotplug_profile hotplug;
 };