nrf,sam,rp2040: add machine.HardwareID function

src/machine/machine_atsam.go

@@ -0,0 +1,31 @@
+//go:build sam
+
+package machine
+
+import (
+	"runtime/volatile"
+	"unsafe"
+)
+
+var deviceID [16]byte
+
+// DeviceID returns an identifier that is unique within
+// a particular chipset.
+//
+// The identity is one burnt into the MCU itself, or the
+// flash chip at time of manufacture.
+//
+// It's possible that two different vendors may allocate
+// the same DeviceID, so callers should take this into
+// account if needing to generate a globally unique id.
+//
+// The length of the hardware ID is vendor-specific, but
+// 8 bytes (64 bits) and 16 bytes (128 bits) are common.
+func DeviceID() []byte {
+	for i := 0; i < len(deviceID); i++ {
+		word := (*volatile.Register32)(unsafe.Pointer(deviceIDAddr[i/4])).Get()
+		deviceID[i] = byte(word >> ((i % 4) * 8))
+	}
+
+	return deviceID[:]
+}