[PATCH] ACPI: introduce .handle_children flag for acpi scan handler

[Zhang Rui]

For some devices with scan handler attached, their children devices
are enumerated by the scan handler, indirectly, as well.

In this case, we do not want to enumerate the children devices in
acpi scan code explicitly.

Thus a new flag .handle_children is introduced in this patch.

For scan handlers with this flag set, we will do default enumeration neither
for the attached devices nor for the children of the attached devices.

Signed-off-by: Zhang Rui <rui.zhang@xxxxxxxxx>
---
 drivers/acpi/acpi_lpss.c |    1 +
 drivers/acpi/scan.c      |   28 ++++++++++++++++++++++++++--
 include/acpi/acpi_bus.h  |    4 +++-
 3 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/drivers/acpi/acpi_lpss.c b/drivers/acpi/acpi_lpss.c
index cfbf2c0..9857343 100644
--- a/drivers/acpi/acpi_lpss.c
+++ b/drivers/acpi/acpi_lpss.c
@@ -453,6 +453,7 @@ static int acpi_lpss_dummy_attach(struct acpi_device *adev,
 static struct acpi_scan_handler lpss_dummy_handler = {
 	.ids = acpi_lpss_device_ids,
 	.attach = acpi_lpss_dummy_attach,
+	.handle_children = true,
 };
 
 void __init acpi_lpss_init(void)
diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index c0456e7..cd833f4 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -2016,6 +2016,31 @@ static acpi_status acpi_bus_check_add(acpi_handle handle, u32 lvl_not_used,
 	return AE_OK;
 }
 
+static void acpi_do_default_enumeration(struct acpi_device *device)
+{
+	/*
+	 * Do not do enumeration for device object that
+	 * its parent doesn't want to
+	 */
+	if (device->parent && device->parent->flags.no_child_enumeration) {
+		device->flags.no_child_enumeration = 1;
+		return;
+	}
+
+	/* Do not do enumeration for device object with scan handler attached */
+	if (device->handler) {
+		if (device->handler->handle_children)
+			device->flags.no_child_enumeration = 1;
+		return;
+	}
+
+	/* Do not do enumeration for device object w/o platform_id */
+	if (!device->pnp.type.platform_id)
+		return;
+
+	acpi_create_platform_device(device, NULL);
+}
+
 static int acpi_scan_attach_handler(struct acpi_device *device)
 {
 	struct acpi_hardware_id *hwid;
@@ -2035,8 +2060,7 @@ static int acpi_scan_attach_handler(struct acpi_device *device)
 		}
 	}
 end:
-	if (device->pnp.type.platform_id && !device->handler)
-		acpi_create_platform_device(device, NULL);
+	acpi_do_default_enumeration(device);
 	return ret;
 }
 
diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
index f998746..bc7235f 100644
--- a/include/acpi/acpi_bus.h
+++ b/include/acpi/acpi_bus.h
@@ -135,6 +135,7 @@ struct acpi_scan_handler {
 	int (*attach)(struct acpi_device *dev, const struct acpi_device_id *id);
 	void (*detach)(struct acpi_device *dev);
 	struct acpi_hotplug_profile hotplug;
+	bool handle_children;
 };
 
 /*
@@ -191,7 +192,8 @@ struct acpi_device_flags {
 	u32 initialized:1;
 	u32 visited:1;
 	u32 no_hotplug:1;
-	u32 reserved:24;
+	u32 no_child_enumeration:1;
+	u32 reserved:23;
 };
 
 /* File System */
-- 
1.7.9.5



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