samd21,samd51,nrf52840: move usbcdc to machine/usb/cdc (#2972)

* samd21,samd51,nrf52840: move usbcdc to machine/usb/cdc

src/machine/usb/cdc/usbcdc.go

@@ -0,0 +1,189 @@
+package cdc
+
+import (
+	"errors"
+	"machine"
+	"runtime/interrupt"
+)
+
+var (
+	ErrBufferEmpty = errors.New("USB-CDC buffer empty")
+)
+
+const cdcLineInfoSize = 7
+
+type cdcLineInfo struct {
+	dwDTERate   uint32
+	bCharFormat uint8
+	bParityType uint8
+	bDataBits   uint8
+	lineState   uint8
+}
+
+// Read from the RX buffer.
+func (usbcdc *USBCDC) Read(data []byte) (n int, err error) {
+	// check if RX buffer is empty
+	size := usbcdc.Buffered()
+	if size == 0 {
+		return 0, nil
+	}
+
+	// Make sure we do not read more from buffer than the data slice can hold.
+	if len(data) < size {
+		size = len(data)
+	}
+
+	// only read number of bytes used from buffer
+	for i := 0; i < size; i++ {
+		v, _ := usbcdc.ReadByte()
+		data[i] = v
+	}
+
+	return size, nil
+}
+
+// ReadByte reads a single byte from the RX buffer.
+// If there is no data in the buffer, returns an error.
+func (usbcdc *USBCDC) ReadByte() (byte, error) {
+	// check if RX buffer is empty
+	buf, ok := usbcdc.rxBuffer.Get()
+	if !ok {
+		return 0, ErrBufferEmpty
+	}
+	return buf, nil
+}
+
+// Buffered returns the number of bytes currently stored in the RX buffer.
+func (usbcdc *USBCDC) Buffered() int {
+	return int(usbcdc.rxBuffer.Used())
+}
+
+// Receive handles adding data to the UART's data buffer.
+// Usually called by the IRQ handler for a machine.
+func (usbcdc *USBCDC) Receive(data byte) {
+	usbcdc.rxBuffer.Put(data)
+}
+
+// USBCDC is the USB CDC aka serial over USB interface.
+type USBCDC struct {
+	rxBuffer *rxRingBuffer
+	txBuffer *txRingBuffer
+	waitTxc  bool
+}
+
+var (
+	// USB is a USB CDC interface.
+	USB *USBCDC
+
+	usbLineInfo = cdcLineInfo{115200, 0x00, 0x00, 0x08, 0x00}
+)
+
+// Configure the USB CDC interface. The config is here for compatibility with the UART interface.
+func (usbcdc *USBCDC) Configure(config machine.UARTConfig) error {
+	return nil
+}
+
+// Flush flushes buffered data.
+func (usbcdc *USBCDC) Flush() {
+	mask := interrupt.Disable()
+	if b, ok := usbcdc.txBuffer.Get(); ok {
+		machine.SendUSBInPacket(cdcEndpointIn, b)
+	} else {
+		usbcdc.waitTxc = false
+	}
+	interrupt.Restore(mask)
+}
+
+// Write data to the USBCDC.
+func (usbcdc *USBCDC) Write(data []byte) (n int, err error) {
+	if usbLineInfo.lineState > 0 {
+		mask := interrupt.Disable()
+		usbcdc.txBuffer.Put(data)
+		if !usbcdc.waitTxc {
+			usbcdc.waitTxc = true
+			usbcdc.Flush()
+		}
+		interrupt.Restore(mask)
+	}
+	return len(data), nil
+}
+
+// WriteByte writes a byte of data to the USB CDC interface.
+func (usbcdc *USBCDC) WriteByte(c byte) error {
+	usbcdc.Write([]byte{c})
+	return nil
+}
+
+func (usbcdc *USBCDC) DTR() bool {
+	return (usbLineInfo.lineState & usb_CDC_LINESTATE_DTR) > 0
+}
+
+func (usbcdc *USBCDC) RTS() bool {
+	return (usbLineInfo.lineState & usb_CDC_LINESTATE_RTS) > 0
+}
+
+func cdcCallbackRx(b []byte) {
+	for i := range b {
+		USB.Receive(b[i])
+	}
+}
+
+func cdcSetup(setup machine.USBSetup) bool {
+	if setup.BmRequestType == usb_REQUEST_DEVICETOHOST_CLASS_INTERFACE {
+		if setup.BRequest == usb_CDC_GET_LINE_CODING {
+			var b [cdcLineInfoSize]byte
+			b[0] = byte(usbLineInfo.dwDTERate)
+			b[1] = byte(usbLineInfo.dwDTERate >> 8)
+			b[2] = byte(usbLineInfo.dwDTERate >> 16)
+			b[3] = byte(usbLineInfo.dwDTERate >> 24)
+			b[4] = byte(usbLineInfo.bCharFormat)
+			b[5] = byte(usbLineInfo.bParityType)
+			b[6] = byte(usbLineInfo.bDataBits)
+
+			machine.SendUSBInPacket(0, b[:])
+			return true
+		}
+	}
+
+	if setup.BmRequestType == usb_REQUEST_HOSTTODEVICE_CLASS_INTERFACE {
+		if setup.BRequest == usb_CDC_SET_LINE_CODING {
+			b, err := machine.ReceiveUSBControlPacket()
+			if err != nil {
+				return false
+			}
+
+			usbLineInfo.dwDTERate = uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
+			usbLineInfo.bCharFormat = b[4]
+			usbLineInfo.bParityType = b[5]
+			usbLineInfo.bDataBits = b[6]
+		}
+
+		if setup.BRequest == usb_CDC_SET_CONTROL_LINE_STATE {
+			usbLineInfo.lineState = setup.WValueL
+		}
+
+		if setup.BRequest == usb_CDC_SET_LINE_CODING || setup.BRequest == usb_CDC_SET_CONTROL_LINE_STATE {
+			// auto-reset into the bootloader
+			if usbLineInfo.dwDTERate == 1200 && usbLineInfo.lineState&usb_CDC_LINESTATE_DTR == 0 {
+				machine.EnterBootloader()
+			} else {
+				// TODO: cancel any reset
+			}
+			machine.SendZlp()
+		}
+
+		if setup.BRequest == usb_CDC_SEND_BREAK {
+			// TODO: something with this value?
+			// breakValue = ((uint16_t)setup.wValueH << 8) | setup.wValueL;
+			// return false;
+			machine.SendZlp()
+		}
+		return true
+	}
+	return false
+}
+
+func EnableUSBCDC() {
+	machine.USBCDC = New()
+	machine.EnableCDC(USB.Flush, cdcCallbackRx, cdcSetup)
+}