USB: Interface callbacks now return an error code

A non-zero error code returned by the callback causes EP0 to STALL.
This is the common mechanism used in USB to indicate an error while
processing a control request.  This simplifies the implementation
of interface callbacks.

Signed-off-by: Anton Staaf <robotboy@chromium.org>

BRANCH=None
BUG=None
TEST=make buildall -j

Change-Id: I89ceb4892f9f810fcaf6e975e6982fc5b2ae447b
Reviewed-on: https://chromium-review.googlesource.com/232368
Reviewed-by: Anton Staaf <robotboy@chromium.org>
Commit-Queue: Anton Staaf <robotboy@chromium.org>
Tested-by: Anton Staaf <robotboy@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>

4 files changed, 30 insertions, 28 deletions

diff --git a/chip/stm32/usb.c b/chip/stm32/usb.c
index b4dfb31fb5..64bff8bd40 100644
--- a/chip/stm32/usb.c
+++ b/chip/stm32/usb.c
@@ -94,8 +94,9 @@ static void ep0_rx(void)
 	/* interface specific requests */
 	if ((req & USB_RECIP_MASK) == USB_RECIP_INTERFACE) {
 		uint8_t iface = ep0_buf_rx[2] & 0xff;
-		if (iface < USB_IFACE_COUNT)
-			usb_iface_request[iface](ep0_buf_rx, ep0_buf_tx);
+		if (iface < USB_IFACE_COUNT &&
+		    usb_iface_request[iface](ep0_buf_rx, ep0_buf_tx))
+			goto unknown_req;
 		return;
 	}
 
diff --git a/chip/stm32/usb_endpoints.S b/chip/stm32/usb_endpoints.S
index 0c950ccbe1..cc13cadeb3 100644
--- a/chip/stm32/usb_endpoints.S
+++ b/chip/stm32/usb_endpoints.S
@@ -100,6 +100,8 @@ interface  7
 .code 16
 
 .thumb_func
-ep_undefined:
+/* Undefined interface callbacks fail by returning non-zero*/
 iface_undefined:
+	mov r0, #1
+ep_undefined:
 	bx lr
diff --git a/chip/stm32/usb_hid.c b/chip/stm32/usb_hid.c
index 347140f9ac..bdcf09c3f8 100644
--- a/chip/stm32/usb_hid.c
+++ b/chip/stm32/usb_hid.c
@@ -118,7 +118,7 @@ static void hid_reset(void)
 
 USB_DECLARE_EP(USB_EP_HID, hid_tx, hid_tx, hid_reset);
 
-static void hid_iface_request(usb_uint *ep0_buf_rx, usb_uint *ep0_buf_tx)
+static int hid_iface_request(usb_uint *ep0_buf_rx, usb_uint *ep0_buf_tx)
 {
 	if ((ep0_buf_rx[0] == (USB_DIR_IN | USB_RECIP_INTERFACE |
 			      (USB_REQ_GET_DESCRIPTOR << 8))) &&
@@ -132,9 +132,10 @@ static void hid_iface_request(usb_uint *ep0_buf_rx, usb_uint *ep0_buf_tx)
 			  EP_STATUS_OUT);
 		CPRINTF("RPT %04x[l %04x]\n", STM32_USB_EP(0),
 			ep0_buf_rx[3]);
-	} else {
-		STM32_TOGGLE_EP(0, EP_TX_RX_MASK, EP_RX_VALID | EP_TX_STALL, 0);
+		return 0;
 	}
+
+	return 1;
 }
 USB_DECLARE_IFACE(USB_IFACE_HID, hid_iface_request)
 
diff --git a/chip/stm32/usb_ms.c b/chip/stm32/usb_ms.c
index 8c0abbe1d5..329f80e8a1 100644
--- a/chip/stm32/usb_ms.c
+++ b/chip/stm32/usb_ms.c
@@ -163,35 +163,33 @@ static void ms_rx(void)
 USB_DECLARE_EP(USB_EP_MS_TX, ms_tx, ms_tx, ms_tx_reset);
 USB_DECLARE_EP(USB_EP_MS_RX, ms_rx, ms_rx, ms_rx_reset);
 
-static void ms_iface_request(usb_uint *ep0_buf_rx, usb_uint *ep0_buf_tx)
+static int ms_iface_request(usb_uint *ep0_buf_rx, usb_uint *ep0_buf_tx)
 {
 	uint16_t *req = (uint16_t *) ep0_buf_rx;
 
-	if ((req[0] & (USB_DIR_OUT | USB_RECIP_INTERFACE | USB_TYPE_CLASS)) ==
-	    (USB_DIR_OUT | USB_RECIP_INTERFACE | USB_TYPE_CLASS)) {
-		switch (req[0] >> 8) {
-		case USB_MS_REQ_RESET:
-			if (req[1] == 0 && req[2] == USB_IFACE_MS &&
-			    req[3] == 0) {
-				ms_rx_reset();
-			}
+	if ((req[0] & (USB_DIR_OUT | USB_RECIP_INTERFACE | USB_TYPE_CLASS)) !=
+	    (USB_DIR_OUT | USB_RECIP_INTERFACE | USB_TYPE_CLASS))
+		return 1;
+
+	switch (req[0] >> 8) {
+	case USB_MS_REQ_RESET:
+		if (req[1] == 0 && req[2] == USB_IFACE_MS &&
+		    req[3] == 0) {
+			ms_rx_reset();
+		}
 		break;
-		case USB_MS_REQ_GET_MAX_LUN:
-			if (req[1] == 0 && req[2] == USB_IFACE_MS &&
-			    req[3] == 1) {
-				ep0_buf_tx[0] = SCSI_MAX_LUN;
-				btable_ep[0].tx_count = sizeof(uint8_t);
-				STM32_TOGGLE_EP(USB_EP_CONTROL, EP_TX_RX_MASK,
+	case USB_MS_REQ_GET_MAX_LUN:
+		if (req[1] == 0 && req[2] == USB_IFACE_MS &&
+		    req[3] == 1) {
+			ep0_buf_tx[0] = SCSI_MAX_LUN;
+			btable_ep[0].tx_count = sizeof(uint8_t);
+			STM32_TOGGLE_EP(USB_EP_CONTROL, EP_TX_RX_MASK,
 					EP_TX_RX_VALID, 0);
-			}
-		break;
 		}
-	} else {
-		CPRINTF("ms stalling: %x %x %x %x\n",
-			req[0], req[1], req[2], req[3]);
-		STM32_TOGGLE_EP(USB_EP_CONTROL, EP_TX_RX_MASK,
-			EP_RX_VALID | EP_TX_STALL, 0);
+		break;
 	}
+
+	return 0;
 }
 USB_DECLARE_IFACE(USB_IFACE_MS, ms_iface_request);