USB: UHCI: Support big endian GRUSBHC HC

This patch adds support for big endian GRUSBHC UHCI controllers.
The HCD bus glue will probe the register interface to determine
the endianness of the controller.

Tested on GR-LEON4-ITX board which has a controller with little endian
interface and on custom LEON3 board with a BE controller.

Signed-off-by: Jan Andersson <jan@gaisler.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 18 insertions, 2 deletions

diff --git a/drivers/usb/host/Kconfig b/drivers/usb/host/Kconfig
index 584424804d0b..ab085f12d570 100644
--- a/drivers/usb/host/Kconfig
+++ b/drivers/usb/host/Kconfig
@@ -418,11 +418,13 @@ config USB_UHCI_SUPPORT_NON_PCI_HC
 
 config USB_UHCI_BIG_ENDIAN_MMIO
         bool
-        depends on USB_UHCI_SUPPORT_NON_PCI_HC
+        depends on USB_UHCI_SUPPORT_NON_PCI_HC && SPARC_LEON
+        default y
 
 config USB_UHCI_BIG_ENDIAN_DESC
         bool
-        depends on USB_UHCI_SUPPORT_NON_PCI_HC
+        depends on USB_UHCI_SUPPORT_NON_PCI_HC && SPARC_LEON
+        default y
 
 config USB_FHCI_HCD
         tristate "Freescale QE USB Host Controller support"
diff --git a/drivers/usb/host/uhci-grlib.c b/drivers/usb/host/uhci-grlib.c
index b1addd60a1ef..d01c1e227681 100644
--- a/drivers/usb/host/uhci-grlib.c
+++ b/drivers/usb/host/uhci-grlib.c
@@ -25,6 +25,20 @@ static int uhci_grlib_init(struct usb_hcd *hcd)
 {
         struct uhci_hcd *uhci = hcd_to_uhci(hcd);
 
+        /*
+         * Probe to determine the endianness of the controller.
+         * We know that bit 7 of the PORTSC1 register is always set
+         * and bit 15 is always clear.  If uhci_readw() yields a value
+         * with bit 7 (0x80) turned on then the current little-endian
+         * setting is correct.  Otherwise we assume the value was
+         * byte-swapped; hence the register interface and presumably
+         * also the descriptors are big-endian.
+         */
+        if (!(uhci_readw(uhci, USBPORTSC1) & 0x80)) {
+                uhci->big_endian_mmio = 1;
+                uhci->big_endian_desc = 1;
+        }
+
         uhci->rh_numports = uhci_count_ports(hcd);
 
         /* Set up pointers to to generic functions */