[PATCH v2 2/3] usb: dwc3: gadget: Add support for snps,reserved-endpoints property

[Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>]

The snps,reserved-endpoints property lists the reserved endpoints
that shouldn't be used for normal transfers. Add support for that
to the driver.

While at it, make sure we don't crash by a sudden access to those
endpoints in the gadget driver.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
 drivers/usb/dwc3/gadget.c | 60 +++++++++++++++++++++++++++++++++++----
 1 file changed, 55 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index d27af65eb08a..93b1e389a983 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -547,6 +547,7 @@ static int dwc3_gadget_set_xfer_resource(struct dwc3_ep *dep)
 int dwc3_gadget_start_config(struct dwc3 *dwc, unsigned int resource_index)
 {
 	struct dwc3_gadget_ep_cmd_params params;
+	struct dwc3_ep		*dep;
 	u32			cmd;
 	int			i;
 	int			ret;
@@ -563,8 +564,13 @@ int dwc3_gadget_start_config(struct dwc3 *dwc, unsigned int resource_index)
 		return ret;
 
 	/* Reset resource allocation flags */
-	for (i = resource_index; i < dwc->num_eps && dwc->eps[i]; i++)
-		dwc->eps[i]->flags &= ~DWC3_EP_RESOURCE_ALLOCATED;
+	for (i = resource_index; i < dwc->num_eps; i++) {
+		dep = dwc->eps[i];
+		if (!dep)
+			continue;
+
+		dep->flags &= ~DWC3_EP_RESOURCE_ALLOCATED;
+	}
 
 	return 0;
 }
@@ -751,9 +757,11 @@ void dwc3_gadget_clear_tx_fifos(struct dwc3 *dwc)
 
 	dwc->last_fifo_depth = fifo_depth;
 	/* Clear existing TXFIFO for all IN eps except ep0 */
-	for (num = 3; num < min_t(int, dwc->num_eps, DWC3_ENDPOINTS_NUM);
-	     num += 2) {
+	for (num = 3; num < min_t(int, dwc->num_eps, DWC3_ENDPOINTS_NUM); num += 2) {
 		dep = dwc->eps[num];
+		if (!dep)
+			continue;
+
 		/* Don't change TXFRAMNUM on usb31 version */
 		size = DWC3_IP_IS(DWC3) ? 0 :
 			dwc3_readl(dwc->regs, DWC3_GTXFIFOSIZ(num >> 1)) &
@@ -3395,14 +3403,52 @@ static int dwc3_gadget_init_endpoint(struct dwc3 *dwc, u8 epnum)
 	return 0;
 }
 
+static int dwc3_gadget_parse_reserved_endpoints(struct dwc3 *dwc, const char *propname,
+						u8 *eps, u8 num)
+{
+	u8 count;
+	int ret;
+
+	if (!device_property_present(dwc->dev, propname))
+		return 0;
+
+	ret = device_property_count_u8(dwc->dev, propname);
+	if (ret < 0)
+		return ret;
+	count = ret;
+
+	ret = device_property_read_u8_array(dwc->dev, propname, eps, min(num, count));
+	if (ret)
+		return ret;
+
+	return count;
+}
+
 static int dwc3_gadget_init_endpoints(struct dwc3 *dwc, u8 total)
 {
+	const char			*propname = "snps,reserved-endpoints";
 	u8				epnum;
+	u8				eps[DWC3_ENDPOINTS_NUM];
+	u8				count;
+	u8				num;
+	int				ret;
 
 	INIT_LIST_HEAD(&dwc->gadget->ep_list);
 
+	ret = dwc3_gadget_parse_reserved_endpoints(dwc, propname, eps, ARRAY_SIZE(eps));
+	if (ret < 0) {
+		dev_err(dwc->dev, "failed to read %s\n", propname);
+		return ret;
+	}
+	count = ret;
+
 	for (epnum = 0; epnum < total; epnum++) {
-		int			ret;
+		for (num = 0; num < count; num++) {
+			if (epnum == eps[num])
+				break;
+		}
+		if (num < count)
+			continue;
 
 		ret = dwc3_gadget_init_endpoint(dwc, epnum);
 		if (ret)
@@ -3669,6 +3715,8 @@ static bool dwc3_gadget_endpoint_trbs_complete(struct dwc3_ep *dep,
 
 		for (i = 0; i < DWC3_ENDPOINTS_NUM; i++) {
 			dep = dwc->eps[i];
+			if (!dep)
+				continue;
 
 			if (!(dep->flags & DWC3_EP_ENABLED))
 				continue;
@@ -3818,6 +3866,8 @@ static void dwc3_endpoint_interrupt(struct dwc3 *dwc,
 	u8			epnum = event->endpoint_number;
 
 	dep = dwc->eps[epnum];
+	if (!dep)
+		return;
 
 	if (!(dep->flags & DWC3_EP_ENABLED)) {
 		if ((epnum > 1) && !(dep->flags & DWC3_EP_TRANSFER_STARTED))
-- 
2.43.0.rc1.1336.g36b5255a03ac