usb/uhci: Add support for Aspeed BMC SoCs

The Aspeed 2400/2500 families have a variant of UHCI which requires
some quirks to the driver to work:

 - The register offsets are different. We add a remapping helper.

 - All accesses have to be done via 32-bit loads and stores. We
   force all accessors to use readl/writel. This is of no consequence
   for reads as we never read "in the middle" of a register. For writes
   it also works fine as the registers only actually implement the bits
   we try to write (16-bit for the registers accessed with writew and
   8-bit for the register accessed with writeb), so always using a
   32-bit write will have no negative effect. We never do partial writes.

 - The resume detect interrupt is broken

 - The number of ports is (optionally) provided via the device-tree

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
--

v2. Remove the bulk of the #ifdef's

 drivers/usb/host/Kconfig         |  6 ++++-
 drivers/usb/host/uhci-hcd.c      | 17 +++++++++++---
 drivers/usb/host/uhci-hcd.h      | 51 ++++++++++++++++++++++++++++++++++++++++
 drivers/usb/host/uhci-platform.c | 22 ++++++++++++++++-
 4 files changed, 91 insertions(+), 5 deletions(-)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 14 insertions, 3 deletions

diff --git a/drivers/usb/host/uhci-hcd.c b/drivers/usb/host/uhci-hcd.c
index 94b150196d4f..c3267a78c94e 100644
--- a/drivers/usb/host/uhci-hcd.c
+++ b/drivers/usb/host/uhci-hcd.c
@@ -265,9 +265,13 @@ static void configure_hc(struct uhci_hcd *uhci)
 
 static int resume_detect_interrupts_are_broken(struct uhci_hcd *uhci)
 {
-	/* If we have to ignore overcurrent events then almost by definition
-	 * we can't depend on resume-detect interrupts. */
-	if (ignore_oc)
+	/*
+	 * If we have to ignore overcurrent events then almost by definition
+	 * we can't depend on resume-detect interrupts.
+	 *
+	 * Those interrupts also don't seem to work on ASpeed SoCs.
+	 */
+	if (ignore_oc || uhci_is_aspeed(uhci))
 		return 1;
 
 	return uhci->resume_detect_interrupts_are_broken ?
@@ -384,6 +388,13 @@ static void start_rh(struct uhci_hcd *uhci)
 {
 	uhci->is_stopped = 0;
 
+	/*
+	 * Clear stale status bits on Aspeed as we get a stale HCH
+	 * which causes problems later on
+	 */
+	if (uhci_is_aspeed(uhci))
+		uhci_writew(uhci, uhci_readw(uhci, USBSTS), USBSTS);
+
 	/* Mark it configured and running with a 64-byte max packet.
 	 * All interrupts are enabled, even though RESUME won't do anything.
 	 */