arm: rpi_pico: Add boot mode bootloader support

Add early init function for RP2 that checks the retained boot mode and
jumps to the bootloader if requested.

Signed-off-by: Peter Johanson <[email protected]>

Author: petejohanson

modules/hal_rpi_pico/CMakeLists.txt

@@ -56,7 +56,6 @@ if(CONFIG_HAS_RPI_PICO)
     ${rp2_common_dir}/hardware_xosc/xosc.c
     ${rp2_common_dir}/hardware_watchdog/watchdog.c
     ${rp2_common_dir}/pico_platform/platform.c
-    ${rp2_common_dir}/pico_bootrom/bootrom.c
   )
 
   zephyr_include_directories(
@@ -69,12 +68,10 @@ if(CONFIG_HAS_RPI_PICO)
     ${rp2_common_dir}/hardware_sync/include
     ${rp2_common_dir}/hardware_timer/include
     ${rp2_common_dir}/hardware_resets/include
-    ${rp2_common_dir}/pico_bootrom/include
     ${rp2040_dir}/hardware_regs/include
     ${rp2040_dir}/hardware_structs/include
     ${common_dir}/pico_base/include
     ${rp2_common_dir}/pico_platform/include
-    ${rp2_common_dir}/pico_bootrom/include
     ${CMAKE_CURRENT_LIST_DIR}
   )
 
@@ -116,6 +113,11 @@ if(CONFIG_HAS_RPI_PICO)
   zephyr_include_directories_ifdef(CONFIG_PICOSDK_USE_CLAIM
           ${rp2_common_dir}/hardware_claim/include)
 
+  zephyr_library_sources_ifdef(CONFIG_PICOSDK_USE_PICO_BOOTROM
+          ${rp2_common_dir}/pico_bootrom/bootrom.c)
+  zephyr_include_directories_ifdef(CONFIG_PICOSDK_USE_PICO_BOOTROM
+          ${rp2_common_dir}/pico_bootrom/include)
+
   # Some flash driver functions must be executed from the RAM.
   # Originally pico-sdk places them in the RW data section, so this
   # implementation does the same.

modules/hal_rpi_pico/Kconfig

@@ -49,3 +49,8 @@ config PICOSDK_USE_TIMER
 	bool
 	help
 	  Use the TIMER driver from pico-sdk
+
+config PICOSDK_USE_PICO_BOOTROM
+	bool
+	help
+	  Use the pico bootrom library from pico-sdk

soc/arm/rpi_pico/rp2/CMakeLists.txt

@@ -4,3 +4,4 @@
 zephyr_library()
 
 zephyr_library_sources(soc.c)
+zephyr_library_sources_ifdef(CONFIG_RP2_BOOTLOADER bootloader.c)

soc/arm/rpi_pico/rp2/Kconfig.soc

@@ -17,6 +17,13 @@ config RP2_REQUIRES_SECOND_STAGE_BOOT
 	bool
 	default y if FLASH_LOAD_OFFSET = 0x100
 
+
+config RP2_BOOTLOADER
+	bool
+	default y
+	depends on RETENTION_BOOT_MODE
+	select PICOSDK_USE_PICO_BOOTROM
+
 # Flash type used by the SoC. The board should select the one used.
 
 config RP2_FLASH_W25Q080

soc/arm/rpi_pico/rp2/bootloader.c

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2024 Pete Johanson
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <soc.h>
+#include <zephyr/init.h>
+#include <zephyr/retention/retention.h>
+#include <zephyr/retention/bootmode.h>
+#include <pico/bootrom.h>
+
+static FUNC_NORETURN void jump_to_bootloader(void)
+{
+	uint32_t boot_led_mask = 0;
+
+#if DT_HAS_CHOSEN(zephyr_rpi_pico_boot_led)
+	boot_led_mask = BIT(DT_GPIO_PIN_BY_IDX(DT_CHOSEN(zephyr_rpi_pico_boot_led), gpios, 0));
+#endif
+
+	reset_usb_boot(boot_led_mask,0);
+
+	while (1) { }
+}
+
+static int rp2_bootloader_check_boot_init(void)
+{
+	if (bootmode_check(BOOT_MODE_TYPE_BOOTLOADER) > 0) {
+		bootmode_clear();
+		jump_to_bootloader();
+	}
+
+	return 0;
+}
+
+SYS_INIT(rp2_bootloader_check_boot_init, PRE_KERNEL_2, 0);
+

soc/arm/rpi_pico/rp2/soc.c

@@ -25,21 +25,9 @@
 #include <hardware/regs/resets.h>
 #include <hardware/clocks.h>
 #include <hardware/resets.h>
-#include <pico/bootrom.h>
 
 LOG_MODULE_REGISTER(soc, CONFIG_SOC_LOG_LEVEL);
 
-/* Overrides the weak ARM implementation:
-   Set general purpose retention register and reboot */
-void sys_arch_reboot(int type)
-{
-	if (type != 0) {
-		reset_usb_boot(0,0);
-	} else {
-		NVIC_SystemReset();
-	}
-}
-
 static int rp2040_init(void)
 {
 	reset_block(~(RESETS_RESET_IO_QSPI_BITS | RESETS_RESET_PADS_QSPI_BITS |