usb: r8a66597-hcd: Flush the D-cache for the pipe-in transfer buffers.

This implements the same D-cache flushing logic for r8a66597-hcd as
Catalin's isp1760 (http://patchwork.kernel.org/patch/76391/) change,
with the same note applying here as well:

    When the HDC driver writes the data to the transfer buffers it
    pollutes the D-cache (unlike DMA drivers where the device writes
    the data). If the corresponding pages get mapped into user space,
    there are no additional cache flushing operations performed and
    this causes random user space faults on architectures with
    separate I and D caches (Harvard) or those with aliasing D-cache.

This fixes up crashes during USB boot on SH7724 and others:

	http://marc.info/?l=linux-sh&m=126439837308912&w=2

Reported-by: Goda Yusuke <goda.yusuke@renesas.com>
Tested-by: Goda Yusuke <goda.yusuke@renesas.com>
Cc: stable@kernel.org
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Acked-by: Yoshihiro Shimoda <shimoda.yoshihiro@renesas.com>

drivers/usb/host/r8a66597-hcd.c

@@ -35,7 +35,9 @@
 #include <linux/usb.h>
 #include <linux/platform_device.h>
 #include <linux/io.h>
+#include <linux/mm.h>
 #include <linux/irq.h>
+#include <asm/cacheflush.h>
 
 #include "../core/hcd.h"
 #include "r8a66597.h"
@@ -820,6 +822,26 @@ static void enable_r8a66597_pipe(struct r8a66597 *r8a66597, struct urb *urb,
 	enable_r8a66597_pipe_dma(r8a66597, dev, pipe, urb);
 }
 
+static void r8a66597_urb_done(struct r8a66597 *r8a66597, struct urb *urb,
+			      int status)
+__releases(r8a66597->lock)
+__acquires(r8a66597->lock)
+{
+	if (usb_pipein(urb->pipe) && usb_pipetype(urb->pipe) != PIPE_CONTROL) {
+		void *ptr;
+
+		for (ptr = urb->transfer_buffer;
+		     ptr < urb->transfer_buffer + urb->transfer_buffer_length;
+		     ptr += PAGE_SIZE)
+			flush_dcache_page(virt_to_page(ptr));
+	}
+
+	usb_hcd_unlink_urb_from_ep(r8a66597_to_hcd(r8a66597), urb);
+	spin_unlock(&r8a66597->lock);
+	usb_hcd_giveback_urb(r8a66597_to_hcd(r8a66597), urb, status);
+	spin_lock(&r8a66597->lock);
+}
+
 /* this function must be called with interrupt disabled */
 static void force_dequeue(struct r8a66597 *r8a66597, u16 pipenum, u16 address)
 {
@@ -838,15 +860,9 @@ static void force_dequeue(struct r8a66597 *r8a66597, u16 pipenum, u16 address)
 		list_del(&td->queue);
 		kfree(td);
 
-		if (urb) {
-			usb_hcd_unlink_urb_from_ep(r8a66597_to_hcd(r8a66597),
-					urb);
+		if (urb)
+			r8a66597_urb_done(r8a66597, urb, -ENODEV);
 
-			spin_unlock(&r8a66597->lock);
-			usb_hcd_giveback_urb(r8a66597_to_hcd(r8a66597), urb,
-					-ENODEV);
-			spin_lock(&r8a66597->lock);
-		}
 		break;
 	}
 }
@@ -1283,10 +1299,7 @@ __releases(r8a66597->lock) __acquires(r8a66597->lock)
 		if (usb_pipeisoc(urb->pipe))
 			urb->start_frame = r8a66597_get_frame(hcd);
 
-		usb_hcd_unlink_urb_from_ep(r8a66597_to_hcd(r8a66597), urb);
-		spin_unlock(&r8a66597->lock);
-		usb_hcd_giveback_urb(hcd, urb, status);
-		spin_lock(&r8a66597->lock);
+		r8a66597_urb_done(r8a66597, urb, status);
 	}
 
 	if (restart) {