lib: Add rp2040 build files

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

lib/rp2040/hardware/structs/resets.h

@@ -0,0 +1,22 @@
+/*
+ * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+#ifndef _HARDWARE_STRUCTS_RESETS_H
+#define _HARDWARE_STRUCTS_RESETS_H
+
+#include "hardware/address_mapped.h"
+#include "hardware/regs/resets.h"
+
+/// \tag::resets_hw[]
+typedef struct {
+    io_rw_32 reset;
+    io_rw_32 wdsel;
+    io_rw_32 reset_done;
+} resets_hw_t;
+
+#define resets_hw ((resets_hw_t *const)RESETS_BASE)
+/// \end::resets_hw[]
+
+#endif