xhci: Add option to get next extended capability in list by passing id = 0

Modify xhci_find_next_ext_cap(base, offset, id) to return the next
capability offset if 0 is passed for id. Otherwise it will behave as
previously and return the offset of the next capability with matching id

capability id 0 is not used by xHCI (reserved)

This is useful when we want to loop through all capabilities.

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/host/xhci-ext-caps.h b/drivers/usb/host/xhci-ext-caps.h
index bf7316e130d3a6678bc457c9d9bed9bc9bfaf5e4..631e7cc62604b97ee40f26b04e258c438f2cb90d 100644 (file)
--- a/drivers/usb/host/xhci-ext-caps.h
+++ b/drivers/usb/host/xhci-ext-caps.h
@@ -84,7 +84,8 @@
  * @base       PCI MMIO registers base address.
  * @start      address at which to start looking, (0 or HCC_PARAMS to start at
  *             beginning of list)
- * @id         Extended capability ID to search for.
+ * @id         Extended capability ID to search for, or 0 for the next
+ *             capability
  *
  * Returns the offset of the next matching extended capability structure.
  * Some capabilities can occur several times, e.g., the XHCI_EXT_CAPS_PROTOCOL,
@@ -110,7 +111,7 @@ static inline int xhci_find_next_ext_cap(void __iomem *base, u32 start, int id)
                val = readl(base + offset);
                if (val == ~0)
                        return 0;
-               if (XHCI_EXT_CAPS_ID(val) == id && offset != start)
+               if (offset != start && (id == 0 || XHCI_EXT_CAPS_ID(val) == id))
                        return offset;
 
                next = XHCI_EXT_CAPS_NEXT(val);