remove unicode/utf16 pkg, properly reset EPDATASTATUS register

syoder · syoder · commit efbff512ff3c · 2020-02-04T21:35:28.000-06:00
Previously it was attempting to reset the register by setting it to
zero, but the manual says to reset bits you need to set them to 1. Once
this was changed, the device began properly acknowledging when it
received data from the host on the out endpoint.
diff --git a/src/machine/usb.go b/src/machine/usb.go
@@ -376,6 +376,23 @@ type cdcLineInfo struct {
 	lineState   uint8
 }
 
+// strToUTF16LEDescriptor converts a utf8 string into a string descriptor
+// note: the following code only converts ascii characters to UTF16LE. In order
+// to do a "proper" conversion, we would need to pull in the 'unicode/utf16'
+// package, which at the time this was written added 512 bytes to the compiled
+// binary.
+func strToUTF16LEDescriptor(in string) []byte {
+	size := (len(in) << 1) + 2
+	out := make([]byte, size)
+	out[0] = byte(size)
+	out[1] = 0x03
+	for i, rune := range in {
+		out[(i<<1)+2] = byte(rune)
+		out[(i<<1)+3] = 0
+	}
+	return out
+}
+
 var (
 	// TODO: allow setting these
 	usb_STRING_LANGUAGE     = [2]uint16{(3 << 8) | (2 + 2), 0x0409} // English
diff --git a/src/machine/usb_nrf52840.go b/src/machine/usb_nrf52840.go
@@ -7,7 +7,6 @@ import (
 	"device/nrf"
 	"runtime/interrupt"
 	"runtime/volatile"
-	"unicode/utf16"
 	"unsafe"
 )
 
@@ -21,17 +20,13 @@ type USBCDC struct {
 func (usbcdc USBCDC) WriteByte(c byte) error {
 	// Supposedly to handle problem with Windows USB serial ports?
 	if usbLineInfo.lineState > 0 {
-		cdcInBusy.Set(1)
+		enterCriticalSection()
 		udd_ep_in_cache_buffer[usb_CDC_ENDPOINT_IN][0] = c
 		sendViaEPIn(
 			usb_CDC_ENDPOINT_IN,
 			&udd_ep_in_cache_buffer[usb_CDC_ENDPOINT_IN][0],
 			1,
 		)
-
-		for cdcInBusy.Get() == 1 {
-			arm.Asm("wfi")
-		}
 	}
 
 	return nil
@@ -46,7 +41,8 @@ func (usbcdc USBCDC) RTS() bool {
 }
 
 var (
-	USB                    = USBCDC{Buffer: NewRingBuffer()}
+	USB = USBCDC{Buffer: NewRingBuffer()}
+
 	usbEndpointDescriptors [8]usbDeviceDescriptor
 
 	udd_ep_in_cache_buffer  [7][128]uint8
@@ -68,9 +64,26 @@ var (
 	usbLineInfo      = cdcLineInfo{115200, 0x00, 0x00, 0x08, 0x00}
 	epinen           uint32
 	epouten          uint32
-	cdcInBusy        volatile.Register8
+	easyDMABusy      volatile.Register8
 )
 
+// enterCriticalSection is used to protect access to easyDMA - only one thing
+// can be done with it at a time
+func enterCriticalSection() {
+	waitForEasyDMA()
+	easyDMABusy.SetBits(1)
+}
+
+func waitForEasyDMA() {
+	for easyDMABusy.HasBits(1) {
+		arm.Asm("wfi")
+	}
+}
+
+func exitCriticalSection() {
+	easyDMABusy.ClearBits(1)
+}
+
 // Configure the USB CDC interface. The config is here for compatibility with the UART interface.
 func (usbcdc *USBCDC) Configure(config UARTConfig) {
 	// enable IRQ
@@ -83,7 +96,7 @@ func (usbcdc *USBCDC) Configure(config UARTConfig) {
 
 	// enable interrupt for end of reset and start of frame
 	nrf.USBD.INTENSET.Set(
-		nrf.USBD_INTENSET_SOF |
+		nrf.USBD_INTENSET_EPDATA |
 			nrf.USBD_INTENSET_EP0DATADONE |
 			nrf.USBD_INTENSET_USBEVENT |
 			nrf.USBD_INTENSET_EP0SETUP,
@@ -110,12 +123,6 @@ func (usbcdc *USBCDC) handleInterrupt(interrupt.Interrupt) {
 		nrf.USBD.EVENTCAUSE.Set(0)
 	}
 
-	// Start of frame
-	if nrf.USBD.EVENTS_SOF.Get() == 1 {
-		nrf.USBD.EVENTS_SOF.Set(0)
-		// if you want to blink LED showing traffic, this would be the place...
-	}
-
 	if nrf.USBD.EVENTS_EP0DATADONE.Get() == 1 {
 		// done sending packet - either need to send another or enter status stage
 		nrf.USBD.EVENTS_EP0DATADONE.Set(0)
@@ -164,29 +171,40 @@ func (usbcdc *USBCDC) handleInterrupt(interrupt.Interrupt) {
 	if nrf.USBD.EVENTS_EPDATA.Get() > 0 {
 		nrf.USBD.EVENTS_EPDATA.Set(0)
 		epDataStatus := nrf.USBD.EPDATASTATUS.Get()
-		nrf.USBD.EPDATASTATUS.Set(0)
+		nrf.USBD.EPDATASTATUS.Set(epDataStatus)
 		var i uint32
 		for i = 1; i < uint32(len(endPoints)); i++ {
 			// Check if endpoint has a pending interrupt
-			inDataDone := epDataStatus&(1<<i) > 0
-			outDataDone := epDataStatus&(0x10000<<i) > 0
+			inDataDone := epDataStatus&(nrf.USBD_EPDATASTATUS_EPIN1<<(i-1)) > 0
+			outDataDone := epDataStatus&(nrf.USBD_EPDATASTATUS_EPOUT1<<(i-1)) > 0
 			if inDataDone || outDataDone {
 				switch i {
 				case usb_CDC_ENDPOINT_OUT:
-					nrf.USBD.EPOUT[i].PTR.Set(uint32(uintptr(unsafe.Pointer(&udd_ep_out_cache_buffer[i]))))
-					nrf.USBD.EPOUT[i].MAXCNT.Set(64)
-					nrf.USBD.TASKS_STARTEPOUT[i].Set(1)
-				case usb_CDC_ENDPOINT_IN, usb_CDC_ENDPOINT_ACM:
-					cdcInBusy.Set(0)
+					// setup buffer to receive from host
+					if outDataDone {
+						enterCriticalSection()
+						nrf.USBD.EPOUT[i].PTR.Set(uint32(uintptr(unsafe.Pointer(&udd_ep_out_cache_buffer[i]))))
+						count := nrf.USBD.SIZE.EPOUT[i].Get()
+						nrf.USBD.EPOUT[i].MAXCNT.Set(count)
+						nrf.USBD.TASKS_STARTEPOUT[i].Set(1)
+					}
+				case usb_CDC_ENDPOINT_IN: //, usb_CDC_ENDPOINT_ACM:
+					if inDataDone {
+						exitCriticalSection()
+					}
 				}
 			}
 		}
 	}
 
+	// ENDEPOUT[n] events
 	for i := 0; i < len(endPoints); i++ {
 		if nrf.USBD.EVENTS_ENDEPOUT[i].Get() > 0 {
 			nrf.USBD.EVENTS_ENDEPOUT[i].Set(0)
-			handleEndpoint(uint32(i))
+			if i == usb_CDC_ENDPOINT_OUT {
+				handleEndpoint(uint32(i))
+			}
+			exitCriticalSection()
 		}
 	}
 }
@@ -208,7 +226,6 @@ func initEndpoint(ep, config uint32) {
 		enableEPIn(ep)
 
 	case usb_ENDPOINT_TYPE_BULK | usbEndpointOut:
-		nrf.USBD.INTENSET.Set(nrf.USBD_INTENSET_EPDATA)
 		nrf.USBD.INTENSET.Set(nrf.USBD_INTENSET_ENDEPOUT0 << ep)
 		nrf.USBD.SIZE.EPOUT[ep].Set(0)
 		enableEPOut(ep)
@@ -219,7 +236,6 @@ func initEndpoint(ep, config uint32) {
 		enableEPOut(ep)
 
 	case usb_ENDPOINT_TYPE_BULK | usbEndpointIn:
-		nrf.USBD.INTENSET.Set(nrf.USBD_INTENSET_EPDATA)
 		enableEPIn(ep)
 
 	case usb_ENDPOINT_TYPE_CONTROL:
@@ -238,7 +254,6 @@ func handleStandardSetup(setup usbSetup) bool {
 		buf := []byte{0, 0}
 
 		if setup.bmRequestType != 0 { // endpoint
-			// TODO: actually check if the endpoint in question is currently halted
 			if isEndpointHalt {
 				buf[0] = 1
 			}
@@ -354,9 +369,6 @@ func cdcSetup(setup usbSetup) bool {
 		}
 
 		if setup.bRequest == usb_CDC_SEND_BREAK {
-			// TODO: something with this value?
-			// breakValue = ((uint16_t)setup.wValueH << 8) | setup.wValueL;
-			// return false;
 			nrf.USBD.TASKS_EP0STATUS.Set(1)
 		}
 		return true
@@ -431,11 +443,19 @@ func sendDescriptor(setup usbSetup) {
 
 		case usb_IPRODUCT:
 			b := strToUTF16LEDescriptor(usb_STRING_PRODUCT)
-			sendUSBPacket(0, b[:setup.wLength])
+			if setup.wLength == 2 {
+				sendUSBPacket(0, b[:2])
+			} else {
+				sendUSBPacket(0, b)
+			}
 
 		case usb_IMANUFACTURER:
 			b := strToUTF16LEDescriptor(usb_STRING_MANUFACTURER)
-			sendUSBPacket(0, b[:setup.wLength])
+			if setup.wLength == 2 {
+				sendUSBPacket(0, b[:2])
+			} else {
+				sendUSBPacket(0, b)
+			}
 
 		case usb_ISERIAL:
 			// TODO: allow returning a product serial number
@@ -500,7 +520,7 @@ func sendConfiguration(setup usbSetup) {
 
 func handleEndpoint(ep uint32) {
 	// get data
-	count := int(nrf.USBD.SIZE.EPOUT[ep].Get())
+	count := int(nrf.USBD.EPOUT[ep].AMOUNT.Get())
 
 	// move to ring buffer
 	for i := 0; i < count; i++ {
@@ -516,7 +536,6 @@ func sendViaEPIn(ep uint32, ptr *byte, count int) {
 		uint32(uintptr(unsafe.Pointer(ptr))),
 	)
 	nrf.USBD.EPIN[ep].MAXCNT.Set(uint32(count))
-	nrf.USBD.EVENTS_ENDEPIN[ep].Set(0)
 	nrf.USBD.TASKS_STARTEPIN[ep].Set(1)
 }
 
@@ -529,17 +548,3 @@ func enableEPIn(ep uint32) {
 	epinen = epinen | (nrf.USBD_EPINEN_IN0 << ep)
 	nrf.USBD.EPINEN.Set(epinen)
 }
-
-func strToUTF16LEDescriptor(in string) []byte {
-	runes := []rune(in)
-	encoded := utf16.Encode(runes)
-	size := (len(encoded) << 1) + 2
-	out := make([]byte, size)
-	out[0] = byte(size)
-	out[1] = 0x03
-	for i, value := range encoded {
-		out[(i<<1)+2] = byte(value & 0xff)
-		out[(i<<1)+3] = byte(value >> 8)
-	}
-	return out
-}
