[rp20xx][pico] platform and target for rp20xx and pico board

- just a skeleton to get us started
- cpu feature config and irq names / vectab2 setup done
- pulled in the second stage for pico as a blob for now
- seems to be hard faulting out of systick setup in platform_init()

target/pico/boot.stage2.S

@@ -0,0 +1,69 @@
+// This is a hack
+// TODO: replace with actual second stage boot source
+
+.section .text.boot.secondstage
+
+.word 0x4b32b500
+.word 0x60582021
+.word 0x21026898
+.word 0x60984388
+.word 0x611860d8
+.word 0x4b2e6158
+.word 0x60992100
+.word 0x61592102
+.word 0x22f02101
+.word 0x492b5099
+.word 0x21016019
+.word 0x20356099
+.word 0xf844f000
+.word 0x42902202
+.word 0x2106d014
+.word 0xf0006619
+.word 0x6e19f834
+.word 0x66192101
+.word 0x66182000
+.word 0xf000661a
+.word 0x6e19f82c
+.word 0x6e196e19
+.word 0xf0002005
+.word 0x2101f82f
+.word 0xd1f94208
+.word 0x60992100
+.word 0x6019491b
+.word 0x60592100
+.word 0x481b491a
+.word 0x21016001
+.word 0x21eb6099
+.word 0x21a06619
+.word 0xf0006619
+.word 0x2100f812
+.word 0x49166099
+.word 0x60014814
+.word 0x60992101
+.word 0x2800bc01
+.word 0x4700d000
+.word 0x49134812
+.word 0xc8036008
+.word 0x8808f380
+.word 0xb5034708
+.word 0x20046a99
+.word 0xd0fb4201
+.word 0x42012001
+.word 0xbd03d1f8
+.word 0x6618b502
+.word 0xf7ff6618
+.word 0x6e18fff2
+.word 0xbd026e18
+.word 0x40020000
+.word 0x18000000
+.word 0x00070000
+.word 0x005f0300
+.word 0x00002221
+.word 0x180000f4
+.word 0xa0002022
+.word 0x10000100
+.word 0xe000ed08
+.word 0x00000000
+.word 0x00000000
+.word 0x00000000
+.word 0x7a4eb274

target/pico/include/target/debugconfig.h

@@ -0,0 +1,3 @@
+#pragma once
+
+#define DEBUG_UART 0

target/pico/rules.mk

@@ -0,0 +1,14 @@
+LOCAL_DIR := $(GET_LOCAL_DIR)
+
+MODULE := $(LOCAL_DIR)
+
+PLATFORM := rp20xx
+
+GLOBAL_DEFINES += \
+	TARGET_HAS_DEBUG_LED=1
+
+MODULE_SRCS += \
+	$(LOCAL_DIR)/boot.stage2.S \
+	$(LOCAL_DIR)/target.c
+
+include make/module.mk

target/pico/target.c

@@ -0,0 +1,19 @@
+// Copyright (c) 2020 Brian Swetland
+//
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file or at
+// https://opensource.org/licenses/MIT
+
+#include <target.h>
+#include <platform/gpio.h>
+
+
+void target_early_init(void) {
+}
+
+void target_set_debug_led(unsigned int led, bool on) {
+}
+
+void target_init(void) {
+}
+