ACPI / scan: Introduce struct acpi_scan_handler

Introduce struct acpi_scan_handler for representing objects that
will do configuration tasks depending on ACPI device nodes'
hardware IDs (HIDs).

Currently, those tasks are done either directly by the ACPI namespace
scanning code or by ACPI device drivers designed specifically for
this purpose.  None of the above is desirable, however, because
doing that directly in the namespace scanning code makes that code
overly complicated and difficult to follow and doing that in
"special" device drivers leads to a great deal of confusion about
their role and to confusing interactions with the driver core (for
example, sysfs directories are created for those drivers, but they
are completely unnecessary and only increase the kernel's memory
footprint in vain).

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Yinghai Lu <yinghai@kernel.org>
Acked-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>

1 files changed, 53 insertions, 7 deletions

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index fe9f2c926663..1453cd0672fb 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -53,6 +53,7 @@ static const struct acpi_device_id acpi_platform_device_ids[] = {
 static LIST_HEAD(acpi_device_list);
 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);
 
@@ -62,6 +63,15 @@ struct acpi_device_bus_id{
 	struct list_head node;
 };
 
+int acpi_scan_add_handler(struct acpi_scan_handler *handler)
+{
+	if (!handler || !handler->attach)
+		return -EINVAL;
+
+	list_add_tail(&handler->list_node, &acpi_scan_handlers_list);
+	return 0;
+}
+
 /*
  * Creates hid/cid(s) string needed for modalias and uevent
  * e.g. on a device with hid:IBM0001 and cid:ACPI0001 you get:
@@ -1570,20 +1580,42 @@ static acpi_status acpi_bus_check_add(acpi_handle handle, u32 lvl_not_used,
 	return AE_OK;
 }
 
+static int acpi_scan_attach_handler(struct acpi_device *device)
+{
+	struct acpi_scan_handler *handler;
+	int ret = 0;
+
+	list_for_each_entry(handler, &acpi_scan_handlers_list, list_node) {
+		const struct acpi_device_id *id;
+
+		id = __acpi_match_device(device, handler->ids);
+		if (!id)
+			continue;
+
+		ret = handler->attach(device, id);
+		if (ret > 0) {
+			device->handler = handler;
+			break;
+		} else if (ret < 0) {
+			break;
+		}
+	}
+	return ret;
+}
+
 static acpi_status acpi_bus_device_attach(acpi_handle handle, u32 lvl_not_used,
 					  void *not_used, void **ret_not_used)
 {
 	const struct acpi_device_id *id;
-	acpi_status status = AE_OK;
 	struct acpi_device *device;
 	unsigned long long sta_not_used;
-	int type_not_used;
+	int ret;
 
 	/*
 	 * Ignore errors ignored by acpi_bus_check_add() to avoid terminating
 	 * namespace walks prematurely.
 	 */
-	if (acpi_bus_type_and_status(handle, &type_not_used, &sta_not_used))
+	if (acpi_bus_type_and_status(handle, &ret, &sta_not_used))
 		return AE_OK;
 
 	if (acpi_bus_get_device(handle, &device))
@@ -1593,10 +1625,15 @@ static acpi_status acpi_bus_device_attach(acpi_handle handle, u32 lvl_not_used,
 	if (id) {
 		/* This is a known good platform device. */
 		acpi_create_platform_device(device, id->driver_data);
-	} else if (device_attach(&device->dev) < 0) {
-		status = AE_CTRL_DEPTH;
+		return AE_OK;
 	}
-	return status;
+
+	ret = acpi_scan_attach_handler(device);
+	if (ret)
+		return ret > 0 ? AE_OK : AE_CTRL_DEPTH;
+
+	ret = device_attach(&device->dev);
+	return ret >= 0 ? AE_OK : AE_CTRL_DEPTH;
 }
 
 /**
@@ -1639,8 +1676,17 @@ static acpi_status acpi_bus_device_detach(acpi_handle handle, u32 lvl_not_used,
 	struct acpi_device *device = NULL;
 
 	if (!acpi_bus_get_device(handle, &device)) {
+		struct acpi_scan_handler *dev_handler = device->handler;
+
 		device->removal_type = ACPI_BUS_REMOVAL_EJECT;
-		device_release_driver(&device->dev);
+		if (dev_handler) {
+			if (dev_handler->detach)
+				dev_handler->detach(device);
+
+			device->handler = NULL;
+		} else {
+			device_release_driver(&device->dev);
+		}
 	}
 	return AE_OK;
 }