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>

2 files changed, 28 insertions, 5 deletions

diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
index 642554b1b60c..de4d57114fe4 100644
--- a/drivers/acpi/pci_root.c
+++ b/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
          * -------
diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index 2ed3f10d0860..8a1f02c3c915 100644
--- a/drivers/pci/pci-acpi.c
+++ b/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;
 }