ACPI/PCI: call _OSC support during root bridge discovery

Add pci_acpi_osc_support() and call it when a PCI bridge is added.  This
allows us to avoid having every individual PCI root bridge driver call
_OSC support for every root bridge in their probe functions, a
significant savings in boot time.
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

drivers/acpi/pci_root.c

@@ -31,6 +31,7 @@
 #include <linux/spinlock.h>
 #include <linux/pm.h>
 #include <linux/pci.h>
+#include <linux/pci-acpi.h>
 #include <linux/acpi.h>
 #include <acpi/acpi_bus.h>
 #include <acpi/acpi_drivers.h>
@@ -193,6 +194,7 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
 	unsigned long long value = 0;
 	acpi_handle handle = NULL;
 	struct acpi_device *child;
+	u32 flags;
 
 
 	if (!device)
@@ -210,6 +212,13 @@ static int __devinit acpi_pci_root_add(struct acpi_device *device)
 
 	device->ops.bind = acpi_pci_bind;
 
+	/*
+	 * All supported architectures that use ACPI have support for
+	 * PCI domains, so we indicate this in _OSC support capabilities.
+	 */
+	flags = OSC_PCI_SEGMENT_GROUPS_SUPPORT;
+	pci_acpi_osc_support(device->handle, flags);
+
 	/* 
 	 * Segment
 	 * -------

drivers/pci/pci-acpi.c

@@ -143,28 +143,42 @@ static acpi_status __acpi_query_osc(u32 flags, struct acpi_osc_data *osc_data,
 	return status;
 }
 
-static acpi_status acpi_query_osc(acpi_handle handle,
-				  u32 level, void *context, void **retval)
+/*
+ * pci_acpi_osc_support: Invoke _OSC indicating support for the given feature
+ * @flags: Bitmask of flags to support
+ *
+ * See the ACPI spec for the definition of the flags
+ */
+int pci_acpi_osc_support(acpi_handle handle, u32 flags)
 {
+	u32 dummy;
 	acpi_status status;
-	struct acpi_osc_data *osc_data;
-	u32 flags = (unsigned long)context, dummy;
 	acpi_handle tmp;
+	struct acpi_osc_data *osc_data;
+	int rc = 0;
 
 	status = acpi_get_handle(handle, "_OSC", &tmp);
 	if (ACPI_FAILURE(status))
-		return AE_OK;
+		return -ENOTTY;
 
 	mutex_lock(&pci_acpi_lock);
 	osc_data = acpi_get_osc_data(handle);
 	if (!osc_data) {
 		printk(KERN_ERR "acpi osc data array is full\n");
+		rc = -ENOMEM;
 		goto out;
 	}
 
 	__acpi_query_osc(flags, osc_data, &dummy);
 out:
 	mutex_unlock(&pci_acpi_lock);
+	return rc;
+}
+
+static acpi_status acpi_query_osc(acpi_handle handle, u32 level,
+				  void *context, void **retval)
+{
+	pci_acpi_osc_support(handle, (unsigned long)context);
 	return AE_OK;
 }
 

include/linux/pci-acpi.h

@@ -51,6 +51,7 @@
 #ifdef CONFIG_ACPI
 extern acpi_status pci_osc_control_set(acpi_handle handle, u32 flags);
 extern acpi_status __pci_osc_support_set(u32 flags, const char *hid);
+int pci_acpi_osc_support(acpi_handle handle, u32 flags);
 static inline acpi_status pci_osc_support_set(u32 flags)
 {
 	return __pci_osc_support_set(flags, PCI_ROOT_HID_STRING);