USB: Implement support for EHCI with big endian MMIO

This patch implements supports for EHCI controllers whose MMIO
registers are big endian and enables that functionality for
the Toshiba SCC chip. It does _not_ add support for big endian
in-memory data structures as this is not needed for that chip
and I hope it will never be.

The guts of the patch are to convert readl(...) to
ehci_readl(ehci, ...) and similarly for register writes.

Signed-off-by: Kou Ishizaki <kou.ishizaki@toshiba.co.jp>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: Geoff Levand <geoffrey.levand@am.sony.com>
Acked-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 32 insertions, 0 deletions

diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index 74dbc6c8228f..5f28b74bb8d3 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -92,6 +92,7 @@ struct ehci_hcd {			/* one per controller */
 	unsigned		is_tdi_rh_tt:1;	/* TDI roothub with TT */
 	unsigned		no_selective_suspend:1;
 	unsigned		has_fsl_port_bug:1; /* FreeScale */
+	unsigned		big_endian_mmio:1;
 
 	u8			sbrn;		/* packed release number */
 
@@ -651,6 +652,37 @@ ehci_port_speed(struct ehci_hcd *ehci, unsigned int portsc)
 #define	ehci_has_fsl_portno_bug(e)		(0)
 #endif
 
+/*
+ * While most USB host controllers implement their registers in
+ * little-endian format, a minority (celleb companion chip) implement
+ * them in big endian format.
+ *
+ * This attempts to support either format at compile time without a
+ * runtime penalty, or both formats with the additional overhead
+ * of checking a flag bit.
+ */
+
+#ifdef CONFIG_USB_EHCI_BIG_ENDIAN_MMIO
+#define ehci_big_endian_mmio(e)		((e)->big_endian_mmio)
+#else
+#define ehci_big_endian_mmio(e)		0
+#endif
+
+static inline unsigned int ehci_readl (const struct ehci_hcd *ehci,
+				       __u32 __iomem * regs)
+{
+	return ehci_big_endian_mmio(ehci) ?
+		readl_be((__force u32 *)regs) :
+		readl((__force u32 *)regs);
+}
+
+static inline void ehci_writel (const struct ehci_hcd *ehci,
+				const unsigned int val, __u32 __iomem *regs)
+{
+	ehci_big_endian_mmio(ehci) ?
+		writel_be(val, (__force u32 *)regs) :
+		writel(val, (__force u32 *)regs);
+}
 
 /*-------------------------------------------------------------------------*/