lib: Add rp2040 build files

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

lib/rp2040/hardware/structs/uart.h

@@ -0,0 +1,35 @@
+/*
+ * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef _HARDWARE_STRUCTS_UART_H
+#define _HARDWARE_STRUCTS_UART_H
+
+#include "hardware/address_mapped.h"
+#include "hardware/regs/uart.h"
+
+typedef struct {
+    io_rw_32 dr;
+    io_rw_32 rsr;
+    uint32_t _pad0[4];
+    io_rw_32 fr;
+    uint32_t _pad1;
+    io_rw_32 ilpr;
+    io_rw_32 ibrd;
+    io_rw_32 fbrd;
+    io_rw_32 lcr_h;
+    io_rw_32 cr;
+    io_rw_32 ifls;
+    io_rw_32 imsc;
+    io_rw_32 ris;
+    io_rw_32 mis;
+    io_rw_32 icr;
+    io_rw_32 dmacr;
+} uart_hw_t;
+
+#define uart0_hw ((uart_hw_t *const)UART0_BASE)
+#define uart1_hw ((uart_hw_t *const)UART1_BASE)
+
+#endif