SoC: stm32c0 support (#3174)

deps: Use hal_stm32 with stm32c0 USB device fixes.

Pull in ZMK fork of hal_stm32 with USB device driver fixes for stm32c0.

feat: Add nBOOT_SEL bit setup for STM32 G0/C0 targets

Newer STM32 C0 and G0 series SoCs do not by default allow use of the
BOOT0 pin/button to enter the bootloader once something has been flash
to the device, which is a change from previous series, and usually not
what's wanted for keyboards running ZMK. To address this, add some
optional, but default initialization code to check the nBOOT_SEL bit and
override it if necessary to ensure BOOT pin/button functionality.

docs: Extract bootloader config into a dedicated page.

Pull the bootloader intergration options out of the system configuration
page into their own dedicated one.

Co-authored-by: Nicolas Munnich <98408764+nmunnich@users.noreply.github.com>

---------

Co-authored-by: Nicolas Munnich <98408764+nmunnich@users.noreply.github.com>

app/src/boot/CMakeLists.txt

@@ -1,3 +1,4 @@
 
 target_sources_ifdef(CONFIG_ZMK_BOOTMODE_TO_MAGIC_VALUE_MAPPER app PRIVATE bootmode_to_magic_mapper.c)
-target_sources_ifdef(CONFIG_ZMK_DBL_TAP_BOOTLOADER app PRIVATE dbl_tap_bootloader.c)
+target_sources_ifdef(CONFIG_ZMK_DBL_TAP_BOOTLOADER app PRIVATE dbl_tap_bootloader.c)
+target_sources_ifdef(CONFIG_ZMK_BOOT_STM32_ENFORCE_NBOOT_SEL app PRIVATE stm32_enforce_nboot_sel.c)

app/src/boot/Kconfig

@@ -41,3 +41,11 @@ config ZMK_BOOTMODE_BOOTLOADER_MAGIC_VALUE
     hex
 
 endif
+
+config ZMK_BOOT_STM32_ENFORCE_NBOOT_SEL
+    bool
+    default y
+    depends on FLASH && (SOC_STM32C071XX || SOC_STM32G0B1XX)
+    select FLASH_EX_OP_ENABLED
+    select FLASH_STM32_OPTION_BYTES
+

app/src/boot/Kconfig.defaults

@@ -25,3 +25,4 @@ config ZMK_BOOTMODE_BOOTLOADER_MAGIC_VALUE
     default 0x57 if ZMK_BOOTMODE_MAGIC_VALUE_BOOTLOADER_TYPE_ADAFRUIT_NRF52
 
 endif
+

app/src/boot/stm32_enforce_nboot_sel.c

@@ -0,0 +1,46 @@
+#include <soc.h>
+#include <zephyr/kernel.h>
+#include <zephyr/init.h>
+#include <zephyr/drivers/flash.h>
+#include <zephyr/drivers/flash/stm32_flash_api_extensions.h>
+#include <zephyr/storage/flash_map.h>
+
+#include <zephyr/logging/log.h>
+
+LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);
+
+const struct device *flash_dev = FIXED_PARTITION_DEVICE(storage_partition);
+
+static int stm32_enforce_nboot_sel_init(void) {
+    uint32_t opts = 0;
+    int ret = 0;
+
+    if (!device_is_ready(flash_dev)) {
+        LOG_ERR("flash dev not ready");
+        return 0;
+    }
+
+    ret = flash_ex_op(flash_dev, FLASH_STM32_EX_OP_OPTB_READ, (uintptr_t)NULL, &opts);
+
+    if (ret < 0) {
+        LOG_ERR("Failed to read option bytes with flash ext op (%d)\n", ret);
+        return ret;
+    }
+
+    LOG_DBG("Current option bytes: %02X\n", opts);
+
+    if (opts & FLASH_OPTR_nBOOT_SEL) {
+        WRITE_BIT(opts, FLASH_OPTR_nBOOT_SEL_Pos, false);
+
+        LOG_DBG("Writing new option bytes %02X\n", opts);
+        ret = flash_ex_op(flash_dev, FLASH_STM32_EX_OP_OPTB_WRITE, opts, NULL);
+        if (ret < 0) {
+            LOG_ERR("Failed to write new option bytes (%d)", ret);
+            return ret;
+        }
+    }
+
+    return 0;
+}
+
+SYS_INIT(stm32_enforce_nboot_sel_init, APPLICATION, 10);

app/west.yml

@@ -28,6 +28,12 @@ manifest:
           - openthread
           - edtt
           - trusted-firmware-m
+    - name: hal_stm32
+      revision: 4fcc3a3f32abe1c4cb76d9d1cef967728dd03908
+      path: modules/hal/stm32
+      remote: zmkfirmware
+      groups:
+        - hal
     - name: lvgl
       revision: f1db87ee98f1810328a8419572fa42a3b5f352ae
       path: modules/lib/gui/lvgl