1 files changed, 62 insertions, 0 deletions
diff --git a/src/machine/machine_rp2_watchdog.go b/src/machine/machine_rp2_watchdog.go
new file mode 100644
index 000000000..f776c5ca4
--- /dev/null
+++ b/src/machine/machine_rp2_watchdog.go
@@ -0,0 +1,62 @@
+//go:build rp2040 || rp2350
+
+package machine
+
+import (
+	"device/rp"
+)
+
+// Watchdog provides access to the hardware watchdog available
+// in the RP2040.
+var Watchdog = &watchdogImpl{}
+
+const (
+	// WatchdogMaxTimeout in milliseconds (approx 8.3s).
+	//
+	// Nominal 1us per watchdog tick, 24-bit counter,
+	// but due to errata two ticks consumed per 1us.
+	// See: Errata RP2040-E1
+	WatchdogMaxTimeout = (rp.WATCHDOG_LOAD_LOAD_Msk / 1000) / 2
+)
+
+type watchdogImpl struct {
+	// The value to reset the counter to on each Update
+	loadValue uint32
+}
+
+// Configure the watchdog.
+//
+// This method should not be called after the watchdog is started and on
+// some platforms attempting to reconfigure after starting the watchdog
+// is explicitly forbidden / will not work.
+func (wd *watchdogImpl) Configure(config WatchdogConfig) error {
+	// x2 due to errata RP2040-E1
+	wd.loadValue = config.TimeoutMillis * 1000 * 2
+	if wd.loadValue > rp.WATCHDOG_LOAD_LOAD_Msk {
+		wd.loadValue = rp.WATCHDOG_LOAD_LOAD_Msk
+	}
+
+	rp.WATCHDOG.CTRL.ClearBits(rp.WATCHDOG_CTRL_ENABLE)
+
+	// Reset everything apart from ROSC and XOSC
+	rp.PSM.WDSEL.Set(0x0001ffff &^ (rp.PSM_WDSEL_ROSC | rp.PSM_WDSEL_XOSC))
+
+	// Pause watchdog during debug
+	rp.WATCHDOG.CTRL.SetBits(rp.WATCHDOG_CTRL_PAUSE_DBG0 | rp.WATCHDOG_CTRL_PAUSE_DBG1 | rp.WATCHDOG_CTRL_PAUSE_JTAG)
+
+	// Load initial counter
+	rp.WATCHDOG.LOAD.Set(wd.loadValue)
+
+	return nil
+}
+
+// Starts the watchdog.
+func (wd *watchdogImpl) Start() error {
+	rp.WATCHDOG.CTRL.SetBits(rp.WATCHDOG_CTRL_ENABLE)
+	return nil
+}
+
+// Update the watchdog, indicating that the app is healthy.
+func (wd *watchdogImpl) Update() {
+	rp.WATCHDOG.LOAD.Set(wd.loadValue)
+}