platform/avr: add reset to bootloader and reset functions

Signed-off-by: Rafael Silva <perigoso@riseup.net>

Author: perigoso

src/platform/avr/boot.c

@@ -0,0 +1,24 @@
+/*
+ * SPDX-License-Identifier: MIT
+ * SPDX-FileCopyrightText: 2022 Rafael Silva <silvagracarafael@gmail.com>
+ */
+
+#include <avr/wdt.h>
+
+// Assuming the Caterina bootloader that comes with the 32u4
+uint16_t bootKey = 0x7777;
+volatile uint16_t *const bootKeyPtr = (volatile uint16_t *) 0x0800;
+
+void reset()
+{
+	wdt_enable(WDTO_15MS);
+	for (;;) {
+	}
+}
+
+void bootloader()
+{
+	*bootKeyPtr = bootKey;
+
+	reset();
+}

src/platform/avr/boot.h

@@ -0,0 +1,8 @@
+/*
+ * SPDX-License-Identifier: MIT
+ * SPDX-FileCopyrightText: 2022 Rafael Silva <perigoso@riseup.net>
+ */
+
+void reset() __attribute__((noreturn));
+void bootloader() __attribute__((noreturn));
+;