machine: implement usb receive message throttling

src/machine/machine_atsamd21_usb.go

@@ -194,10 +194,9 @@ func handleUSBIRQ(intr interrupt.Interrupt) {
 		setEPINTFLAG(i, epFlags)
 		if (epFlags & sam.USB_DEVICE_EPINTFLAG_TRCPT0) > 0 {
 			buf := handleEndpointRx(i)
-			if usbRxHandler[i] != nil {
+			if usbRxHandler[i] == nil || usbRxHandler[i](buf) {
-				usbRxHandler[i](buf)
+				AckUsbOutTransfer(i)
 			}
-			handleEndpointRxComplete(i)
 		} else if (epFlags & sam.USB_DEVICE_EPINTFLAG_TRCPT1) > 0 {
 			if usbTxHandler[i] != nil {
 				usbTxHandler[i]()
@@ -417,7 +416,8 @@ func handleEndpointRx(ep uint32) []byte {
 	return udd_ep_out_cache_buffer[ep][:count]
 }
 
-func handleEndpointRxComplete(ep uint32) {
+// AckUsbOutTransfer is called to acknowledge the completion of a USB OUT transfer.
+func AckUsbOutTransfer(ep uint32) {
 	// set byte count to zero
 	usbEndpointDescriptors[ep].DeviceDescBank[0].PCKSIZE.ClearBits(usb_DEVICE_PCKSIZE_BYTE_COUNT_Mask << usb_DEVICE_PCKSIZE_BYTE_COUNT_Pos)
 

src/machine/machine_atsamd51_usb.go

@@ -197,10 +197,9 @@ func handleUSBIRQ(intr interrupt.Interrupt) {
 		setEPINTFLAG(i, epFlags)
 		if (epFlags & sam.USB_DEVICE_ENDPOINT_EPINTFLAG_TRCPT0) > 0 {
 			buf := handleEndpointRx(i)
-			if usbRxHandler[i] != nil {
+			if usbRxHandler[i] == nil || usbRxHandler[i](buf) {
-				usbRxHandler[i](buf)
+				AckUsbOutTransfer(i)
 			}
-			handleEndpointRxComplete(i)
 		} else if (epFlags & sam.USB_DEVICE_ENDPOINT_EPINTFLAG_TRCPT1) > 0 {
 			if usbTxHandler[i] != nil {
 				usbTxHandler[i]()
@@ -420,7 +419,8 @@ func handleEndpointRx(ep uint32) []byte {
 	return udd_ep_out_cache_buffer[ep][:count]
 }
 
-func handleEndpointRxComplete(ep uint32) {
+// AckUsbOutTransfer is called to acknowledge the completion of a USB OUT transfer.
+func AckUsbOutTransfer(ep uint32) {
 	// set byte count to zero
 	usbEndpointDescriptors[ep].DeviceDescBank[0].PCKSIZE.ClearBits(usb_DEVICE_PCKSIZE_BYTE_COUNT_Mask << usb_DEVICE_PCKSIZE_BYTE_COUNT_Pos)
 

src/machine/machine_nrf52840_usb.go

@@ -206,10 +206,9 @@ func handleUSBIRQ(interrupt.Interrupt) {
 		if nrf.USBD.EVENTS_ENDEPOUT[i].Get() > 0 {
 			nrf.USBD.EVENTS_ENDEPOUT[i].Set(0)
 			buf := handleEndpointRx(uint32(i))
-			if usbRxHandler[i] != nil {
+			if usbRxHandler[i] == nil || usbRxHandler[i](buf) {
-				usbRxHandler[i](buf)
+				AckUsbOutTransfer(uint32(i))
 			}
-			handleEndpointRxComplete(uint32(i))
 			exitCriticalSection()
 		}
 	}
@@ -304,7 +303,8 @@ func handleEndpointRx(ep uint32) []byte {
 	return udd_ep_out_cache_buffer[ep][:count]
 }
 
-func handleEndpointRxComplete(ep uint32) {
+// AckUsbOutTransfer is called to acknowledge the completion of a USB OUT transfer.
+func AckUsbOutTransfer(ep uint32) {
 	// set ready for next data
 	nrf.USBD.SIZE.EPOUT[ep].Set(0)
 }

src/machine/machine_rp2040_usb.go

@@ -95,10 +95,9 @@ func handleUSBIRQ(intr interrupt.Interrupt) {
 		for i := 0; i < 16; i++ {
 			if s2&(1<<(i*2+1)) > 0 {
 				buf := handleEndpointRx(uint32(i))
-				if usbRxHandler[i] != nil {
+				if usbRxHandler[i] == nil || usbRxHandler[i](buf) {
-					usbRxHandler[i](buf)
+					AckUsbOutTransfer(uint32(i))
 				}
-				handleEndpointRxComplete(uint32(i))
 			}
 		}
 

src/machine/machine_rp2350_usb.go

@@ -98,10 +98,9 @@ func handleUSBIRQ(intr interrupt.Interrupt) {
 		for i := 0; i < 16; i++ {
 			if s2&(1<<(i*2+1)) > 0 {
 				buf := handleEndpointRx(uint32(i))
-				if usbRxHandler[i] != nil {
+				if usbRxHandler[i] == nil || usbRxHandler[i](buf) {
-					usbRxHandler[i](buf)
+					AckUsbOutTransfer(uint32(i))
 				}
-				handleEndpointRxComplete(uint32(i))
 			}
 		}
 

src/machine/machine_rp2_usb.go

@@ -128,7 +128,8 @@ func handleEndpointRx(ep uint32) []byte {
 	return _usbDPSRAM.EPxBuffer[ep].Buffer0[:sz]
 }
 
-func handleEndpointRxComplete(ep uint32) {
+// AckUsbOutTransfer is called to acknowledge the completion of a USB OUT transfer.
+func AckUsbOutTransfer(ep uint32) {
 	ep = ep & 0x7F
 	setEPDataPID(ep, !epXdata0[ep])
 }

src/machine/usb.go

@@ -319,7 +319,12 @@ func ConfigureUSBEndpoint(desc descriptor.Descriptor, epSettings []usb.EndpointC
 		} else {
 			endPoints[ep.Index] = uint32(ep.Type | usb.EndpointOut)
 			if ep.RxHandler != nil {
-				usbRxHandler[ep.Index] = ep.RxHandler
+				usbRxHandler[ep.Index] = func(b []byte) bool {
+					ep.RxHandler(b)
+					return true
+				}
+			} else if ep.DelayRxHandler != nil {
+				usbRxHandler[ep.Index] = ep.DelayRxHandler
 			}
 		}
 		if ep.StallHandler != nil {

src/machine/usb/config.go

@@ -1,12 +1,13 @@
 package usb
 
 type EndpointConfig struct {
-	Index        uint8
+	Index          uint8
-	IsIn         bool
+	IsIn           bool
-	TxHandler    func()
+	TxHandler      func()
-	RxHandler    func([]byte)
+	RxHandler      func([]byte)
-	StallHandler func(Setup) bool
+	DelayRxHandler func([]byte) bool
-	Type         uint8
+	StallHandler   func(Setup) bool
+	Type           uint8
 }
 
 type SetupConfig struct {