Merge branch 'x86-mrst-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...

[pandora-kernel.git] / drivers / pci / pci.c

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 5b548ae..77b493b 100644 (file)
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -303,6 +303,49 @@ int pci_find_ext_capability(struct pci_dev *dev, int cap)
 }
 EXPORT_SYMBOL_GPL(pci_find_ext_capability);
 
+/**
+ * pci_bus_find_ext_capability - find an extended capability
+ * @bus:   the PCI bus to query
+ * @devfn: PCI device to query
+ * @cap:   capability code
+ *
+ * Like pci_find_ext_capability() but works for pci devices that do not have a
+ * pci_dev structure set up yet.
+ *
+ * Returns the address of the requested capability structure within the
+ * device's PCI configuration space or 0 in case the device does not
+ * support it.
+ */
+int pci_bus_find_ext_capability(struct pci_bus *bus, unsigned int devfn,
+                               int cap)
+{
+       u32 header;
+       int ttl;
+       int pos = PCI_CFG_SPACE_SIZE;
+
+       /* minimum 8 bytes per capability */
+       ttl = (PCI_CFG_SPACE_EXP_SIZE - PCI_CFG_SPACE_SIZE) / 8;
+
+       if (!pci_bus_read_config_dword(bus, devfn, pos, &header))
+               return 0;
+       if (header == 0xffffffff || header == 0)
+               return 0;
+
+       while (ttl-- > 0) {
+               if (PCI_EXT_CAP_ID(header) == cap)
+                       return pos;
+
+               pos = PCI_EXT_CAP_NEXT(header);
+               if (pos < PCI_CFG_SPACE_SIZE)
+                       break;
+
+               if (!pci_bus_read_config_dword(bus, devfn, pos, &header))
+                       break;
+       }
+
+       return 0;
+}
+
 static int __pci_find_next_ht_cap(struct pci_dev *dev, int pos, int ht_cap)
 {
        int rc, ttl = PCI_FIND_CAP_TTL;