PCI: add a new function to map BAR offsets

Add a function to map a given resource number to a corresponding
register so drivers can get the offset and type of device specific BARs.

Signed-off-by: Yu Zhao <yu.zhao@intel.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 22 insertions, 0 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index deeab19d7d10..7e9c0f3936dd 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2201,6 +2201,28 @@ int pci_select_bars(struct pci_dev *dev, unsigned long flags)
         return bars;
 }
 
+/**
+ * pci_resource_bar - get position of the BAR associated with a resource
+ * @dev: the PCI device
+ * @resno: the resource number
+ * @type: the BAR type to be filled in
+ *
+ * Returns BAR position in config space, or 0 if the BAR is invalid.
+ */
+int pci_resource_bar(struct pci_dev *dev, int resno, enum pci_bar_type *type)
+{
+        if (resno < PCI_ROM_RESOURCE) {
+                *type = pci_bar_unknown;
+                return PCI_BASE_ADDRESS_0 + 4 * resno;
+        } else if (resno == PCI_ROM_RESOURCE) {
+                *type = pci_bar_mem32;
+                return dev->rom_base_reg;
+        }
+
+        dev_err(&dev->dev, "BAR: invalid resource #%d\n", resno);
+        return 0;
+}
+
 static void __devinit pci_no_domains(void)
 {
 #ifdef CONFIG_PCI_DOMAINS