drivers: udc_dwc2: Process SETUP stage when allowed

DWC2 programming guide mentions that SETUP can only be processed by
application after DOEPINTn.SETUP interrupt. Not respecting this
requirement makes setting Global OUT NAK hang while waiting for
GOUTNAKEFF interrupt until the host starts next control transfer.
Global OUT NAK is necessary if the application ever wants to properly
cancel any ongoing transfer.

Change the processing to comply with the programming guide.

Signed-off-by: Tomasz Moń <[email protected]>

Author: tmon-nordic

drivers/usb/udc/udc_dwc2.c

@@ -349,7 +349,7 @@ static inline int dwc2_read_fifo(const struct device *dev, const uint8_t ep,
 				 struct net_buf *const buf, const size_t size)
 {
 	struct usb_dwc2_reg *const base = dwc2_get_base(dev);
-	size_t len = MIN(size, net_buf_tailroom(buf));
+	size_t len = buf ? MIN(size, net_buf_tailroom(buf)) : 0;
 	const size_t d = sizeof(uint32_t);
 
 	/* FIFO access is always in 32-bit words */
@@ -389,7 +389,7 @@ static void dwc2_prep_rx(const struct device *dev,
 
 	doeptsiz = (1 << USB_DWC2_DOEPTSIZ0_PKTCNT_POS) | cfg->mps;
 	if (cfg->addr == USB_CONTROL_EP_OUT) {
-		doeptsiz |= (1 << USB_DWC2_DOEPTSIZ0_SUPCNT_POS);
+		doeptsiz |= (3 << USB_DWC2_DOEPTSIZ0_SUPCNT_POS);
 	}
 
 	sys_write32(doeptsiz, doeptsiz_reg);
@@ -650,7 +650,7 @@ static void dwc2_on_bus_reset(const struct device *dev)
 		}
 	}
 
-	sys_write32(0UL, (mem_addr_t)&base->doepmsk);
+	sys_write32(USB_DWC2_DOEPINT_SETUP, (mem_addr_t)&base->doepmsk);
 	sys_set_bits((mem_addr_t)&base->gintmsk, USB_DWC2_GINTSTS_RXFLVL);
 	sys_set_bits((mem_addr_t)&base->diepmsk, USB_DWC2_DIEPINT_XFERCOMPL);
 
@@ -668,22 +668,36 @@ static void dwc2_handle_enumdone(const struct device *dev)
 	priv->enumspd = usb_dwc2_get_dsts_enumspd(dsts);
 }
 
-static inline int dwc2_read_fifo_setup(const struct device *dev)
+static inline int dwc2_read_fifo_setup(const struct device *dev, uint8_t ep,
+				       const size_t size)
 {
 	struct usb_dwc2_reg *const base = dwc2_get_base(dev);
 	struct udc_dwc2_data *const priv = udc_get_private(dev);
+	size_t offset;
 
 	/* FIFO access is always in 32-bit words */
 
+	if (size != 8) {
+		LOG_ERR("%d bytes SETUP", size);
+	}
+
 	/*
 	 * We store the setup packet temporarily in the driver's private data
 	 * because there is always a race risk after the status stage OUT
 	 * packet from the host and the new setup packet. This is fine in
 	 * bottom-half processing because the events arrive in a queue and
 	 * there will be a next net_buf for the setup packet.
 	 */
-	sys_put_le32(sys_read32(UDC_DWC2_EP_FIFO(base, 0)), priv->setup);
-	sys_put_le32(sys_read32(UDC_DWC2_EP_FIFO(base, 0)), &priv->setup[4]);
+	for (offset = 0; offset < MIN(size, 8); offset += 4) {
+		sys_put_le32(sys_read32(UDC_DWC2_EP_FIFO(base, ep)),
+			     &priv->setup[offset]);
+	}
+
+	/* On protocol error simply discard extra data */
+	while (offset < size) {
+		sys_read32(UDC_DWC2_EP_FIFO(base, ep));
+		offset += 4;
+	}
 
 	return 0;
 }
@@ -706,26 +720,23 @@ static inline void dwc2_handle_rxflvl(const struct device *dev)
 
 	switch (pktsts) {
 	case USB_DWC2_GRXSTSR_PKTSTS_SETUP:
-		evt.type = DWC2_DRV_EVT_SETUP;
-
-		__ASSERT(evt.bcnt == 8, "Incorrect setup packet length");
-		dwc2_read_fifo_setup(dev);
-
-		k_msgq_put(&drv_msgq, &evt, K_NO_WAIT);
+		dwc2_read_fifo_setup(dev, evt.ep, evt.bcnt);
 		break;
 	case USB_DWC2_GRXSTSR_PKTSTS_OUT_DATA:
 		evt.type = DWC2_DRV_EVT_DOUT;
 		ep_cfg = udc_get_ep_cfg(dev, evt.ep);
 
 		buf = udc_buf_peek(dev, ep_cfg->addr);
+
+		/* RxFIFO data must be retrieved even when buf is NULL */
+		dwc2_read_fifo(dev, evt.ep, buf, evt.bcnt);
+
 		if (buf == NULL) {
 			LOG_ERR("No buffer for ep 0x%02x", ep_cfg->addr);
 			udc_submit_event(dev, UDC_EVT_ERROR, -ENOBUFS);
 			break;
 		}
 
-		dwc2_read_fifo(dev, USB_CONTROL_EP_OUT, buf, evt.bcnt);
-
 		if (net_buf_tailroom(buf) && evt.bcnt == ep_cfg->mps) {
 			dwc2_prep_rx(dev, ep_cfg, 0);
 		} else {
@@ -734,9 +745,11 @@ static inline void dwc2_handle_rxflvl(const struct device *dev)
 
 		break;
 	case USB_DWC2_GRXSTSR_PKTSTS_OUT_DATA_DONE:
-	case USB_DWC2_GRXSTSR_PKTSTS_SETUP_DONE:
 		LOG_DBG("RX pktsts DONE");
 		break;
+	case USB_DWC2_GRXSTSR_PKTSTS_SETUP_DONE:
+		LOG_DBG("SETUP pktsts DONE");
+		break;
 	default:
 		break;
 	}
@@ -813,7 +826,6 @@ static inline void dwc2_handle_oepint(const struct device *dev)
 	doepmsk = sys_read32((mem_addr_t)&base->doepmsk);
 	daint = sys_read32((mem_addr_t)&base->daint);
 
-	/* No OUT interrupt expected in FIFO mode, just clear interrupt */
 	for (uint8_t n = 0U; n < n_max; n++) {
 		mem_addr_t doepint_reg = (mem_addr_t)&base->out_ep[n].doepint;
 		uint32_t doepint;
@@ -826,6 +838,16 @@ static inline void dwc2_handle_oepint(const struct device *dev)
 			sys_write32(status, doepint_reg);
 
 			LOG_DBG("ep 0x%02x interrupt status: 0x%x", n, status);
+
+			if (status & USB_DWC2_DOEPINT_SETUP) {
+				struct dwc2_drv_event evt = {
+					.type = DWC2_DRV_EVT_SETUP,
+					.ep = USB_CONTROL_EP_OUT,
+					.bcnt = 8,
+				};
+
+				k_msgq_put(&drv_msgq, &evt, K_NO_WAIT);
+			}
 		}
 	}