USB: Use (get|put)_unaligned for accessing wMaxPacketSize

In 9792987721c7980453fe6447c3fa6593b44f8458 Stefan describes a usecase
where the previous behavior of leaving wMaxPacketSize be unaligned
caused fatal problems.  The initial fix for this problem was incomplete
however as it showed another cases of non-aligned access that previously
worked implicitly.  This switches to making sure that all access of
wMaxPacketSize are done via (get|put)_unaligned.

In order to maintain a level of readability to the code in some cases
we now use a variable for the value of wMaxPacketSize and in others, a
macro.

Cc: Minkyu Kang <mk7.kang@samsung.com>
Cc: Remy Bohmer <linux@bohmer.net>

OpenRISC:
Tested-by: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>

Beagleboard xM, Pandaboard run-tested, s5p_goni build-tested.
Signed-off-by: Tom Rini <trini@ti.com>

2 files changed, 11 insertions, 7 deletions

diff --git a/drivers/usb/gadget/epautoconf.c b/drivers/usb/gadget/epautoconf.c
index 1896489421..5b8776e0b7 100644
--- a/drivers/usb/gadget/epautoconf.c
+++ b/drivers/usb/gadget/epautoconf.c
@@ -25,6 +25,7 @@
 #include <linux/usb/ch9.h>
 #include <asm/errno.h>
 #include <linux/usb/gadget.h>
+#include <asm/unaligned.h>
 #include "gadget_chips.h"
 
 #define isdigit(c)      ('0' <= (c) && (c) <= '9')
@@ -127,7 +128,7 @@ static int ep_matches(
 	 * where it's an output parameter representing the full speed limit.
 	 * the usb spec fixes high speed bulk maxpacket at 512 bytes.
 	 */
-	max = 0x7ff & le16_to_cpu(desc->wMaxPacketSize);
+	max = 0x7ff & le16_to_cpu(get_unaligned(&desc->wMaxPacketSize));
 	switch (type) {
 	case USB_ENDPOINT_XFER_INT:
 		/* INT:  limit 64 bytes full speed, 1024 high speed */
@@ -143,7 +144,8 @@ static int ep_matches(
 			return 0;
 
 		/* BOTH:  "high bandwidth" works only at high speed */
-		if ((desc->wMaxPacketSize & __constant_cpu_to_le16(3<<11))) {
+		if ((get_unaligned(&desc->wMaxPacketSize) &
+					__constant_cpu_to_le16(3<<11))) {
 			if (!gadget->is_dualspeed)
 				return 0;
 			/* configure your hardware with enough buffering!! */
@@ -176,7 +178,7 @@ static int ep_matches(
 		/* min() doesn't work on bitfields with gcc-3.5 */
 		if (size > 64)
 			size = 64;
-		desc->wMaxPacketSize = cpu_to_le16(size);
+		put_unaligned(cpu_to_le16(size), &desc->wMaxPacketSize);
 	}
 	return 1;
 }
diff --git a/drivers/usb/gadget/s3c_udc_otg.c b/drivers/usb/gadget/s3c_udc_otg.c
index 5a3ac78ff2..901fac982a 100644
--- a/drivers/usb/gadget/s3c_udc_otg.c
+++ b/drivers/usb/gadget/s3c_udc_otg.c
@@ -40,6 +40,7 @@
 #include <linux/usb/gadget.h>
 
 #include <asm/byteorder.h>
+#include <asm/unaligned.h>
 #include <asm/io.h>
 
 #include <asm/mach-types.h>
@@ -586,7 +587,8 @@ static int s3c_ep_enable(struct usb_ep *_ep,
 	if (!_ep || !desc || ep->desc || _ep->name == ep0name
 	    || desc->bDescriptorType != USB_DT_ENDPOINT
 	    || ep->bEndpointAddress != desc->bEndpointAddress
-	    || ep_maxpacket(ep) < le16_to_cpu(desc->wMaxPacketSize)) {
+	    || ep_maxpacket(ep) <
+	    le16_to_cpu(get_unaligned(&desc->wMaxPacketSize))) {
 
 		DEBUG("%s: bad ep or descriptor\n", __func__);
 		return -EINVAL;
@@ -603,8 +605,8 @@ static int s3c_ep_enable(struct usb_ep *_ep,
 
 	/* hardware _could_ do smaller, but driver doesn't */
 	if ((desc->bmAttributes == USB_ENDPOINT_XFER_BULK
-	     && le16_to_cpu(desc->wMaxPacketSize) != ep_maxpacket(ep))
-	    || !desc->wMaxPacketSize) {
+	     && le16_to_cpu(get_unaligned(&desc->wMaxPacketSize)) !=
+	     ep_maxpacket(ep)) || !get_unaligned(&desc->wMaxPacketSize)) {
 
 		DEBUG("%s: bad %s maxpacket\n", __func__, _ep->name);
 		return -ERANGE;
@@ -620,7 +622,7 @@ static int s3c_ep_enable(struct usb_ep *_ep,
 	ep->stopped = 0;
 	ep->desc = desc;
 	ep->pio_irqs = 0;
-	ep->ep.maxpacket = le16_to_cpu(desc->wMaxPacketSize);
+	ep->ep.maxpacket = le16_to_cpu(get_unaligned(&desc->wMaxPacketSize));
 
 	/* Reset halt state */
 	s3c_udc_set_nak(ep);