samd21,samd51,nrf52840: add support for USBHID (keyboard / mouse)

src/machine/usb/hid/hid.go

@@ -0,0 +1,51 @@
+package hid
+
+import (
+	"errors"
+	"machine"
+)
+
+// from usb-hid.go
+var (
+	ErrHIDInvalidPort    = errors.New("invalid USB port")
+	ErrHIDInvalidCore    = errors.New("invalid USB core")
+	ErrHIDReportTransfer = errors.New("failed to transfer HID report")
+)
+
+const (
+	hidEndpoint = 4
+)
+
+type hidDevicer interface {
+	Callback() bool
+}
+
+var devices [5]hidDevicer
+var size int
+
+// SetCallbackHandler sets the callback. Only the first time it is called, it
+// calls machine.EnableHID for USB configuration
+func SetCallbackHandler(d hidDevicer) {
+	if size == 0 {
+		machine.EnableHID(callback)
+	}
+
+	devices[size] = d
+	size++
+}
+
+func callback() {
+	for _, d := range devices {
+		if d == nil {
+			continue
+		}
+		if done := d.Callback(); done {
+			return
+		}
+	}
+}
+
+// SendUSBPacket sends a HIDPacket.
+func SendUSBPacket(b []byte) {
+	machine.SendUSBHIDPacket(hidEndpoint, b)
+}