SoC: stm32c0 support

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

docs/docs/config/bootloader.md

@@ -0,0 +1,42 @@
+---
+title: Bootloader Integration Configuration
+sidebar_label: Bootloader Integration
+---
+
+These are general settings that control the various bootloader integration features of ZMK.
+
+See [Configuration Overview](index.md) for instructions on how to change these settings.
+
+## Kconfig
+
+Definition file: [zmk/app/src/boot/Kconfig](https://github.com/zmkfirmware/zmk/blob/main/app/src/boot/Kconfig)
+
+### Double Tap To Bootloader
+
+Some SoCs, like RP2040 or the various STM32 offerings, require holding a certain "boot button" down to enter the bootloader, on a hardware level. To make it easier to enter the bootloader on those platforms, ZMK integrates an optional feature to allow entering the bootloader by simply double tapping reset within the configured timeout period.
+
+| Config                                     | Type | Description                                                         | Default                     |
+| ------------------------------------------ | ---- | ------------------------------------------------------------------- | --------------------------- |
+| `CONFIG_ZMK_DBL_TAP_BOOTLOADER`            | bool | Enable the double-tap to enter bootloader functionality             | y if STM32 or RP2040/RP2350 |
+| `CONFIG_ZMK_DBL_TAP_BOOTLOADER_TIMEOUT_MS` | int  | Duration (in ms) to wait for a second reset to enter the bootloader | 500                         |
+
+### STM32 nBOOT_SEL Option Byte Setup
+
+Some newer STM32 series SoCs, in particular stm32c0 and stm32g0, enable the `nBOOT_SEL` bit of the option bytes by default. This bit prevents entering the system ROM bootloader by holding the BOOT0 pin/button during a reset/startup.
+
+To ensure the BOOT button on keyboard and controllers using these SoCs works as expected after being flashed with ZMK, we check the `nBOOT_SEL` bit on startup and clear it if it is set. Should you _not_ want that functionality, for some reason, this can be disabled.
+
+| Config                                    | Type | Description                           | Default                 |
+| ----------------------------------------- | ---- | ------------------------------------- | ----------------------- |
+| `CONFIG_ZMK_BOOT_STM32_ENFORCE_NBOOT_SEL` | bool | Ensure the `nBOOT_SEL` bit is not set | y if STM32CO or STM32G0 |
+
+### Bootmode Magic Value Mapper
+
+Some target SoCs may use the bootmode magic value mapper for [bootloader integration](docs/development/hardware-integration/bootloader/index.mdx). When doing so, the following configurations are used:
+
+| Config                                                           | Type | Description                                                                           | Default |
+| ---------------------------------------------------------------- | ---- | ------------------------------------------------------------------------------------- | ------- |
+| `CONFIG_ZMK_BOOTMODE_BOOTLOADER_MAGIC_VALUE`                     | hex  | The magic value to place into retained memory when the bootloader boot mode is set    | none    |
+| `CONFIG_ZMK_BOOTMODE_MAGIC_VALUE_BOOTLOADER_TYPE_TINYUF2`        | bool | Used to default the bootloader magic value for the tinyuf2 bootloader                 | false   |
+| `CONFIG_ZMK_BOOTMODE_MAGIC_VALUE_BOOTLOADER_TYPE_ADAFRUIT_BOSSA` | bool | Used to default the bootloader magic value for the Adafruit BOSSA (SAMD21) bootloader | false   |
+| `CONFIG_ZMK_BOOTMODE_MAGIC_VALUE_BOOTLOADER_TYPE_ADAFRUIT_NRF52` | bool | Used to default the bootloader magic value for the Adafruit nRF52 bootloader          | false   |

docs/docs/config/system.md

@@ -120,13 +120,6 @@ Note that `CONFIG_BT_MAX_CONN` and `CONFIG_BT_MAX_PAIRED` should be set to the s
 | `CONFIG_ZMK_USB_LOGGING` | bool | Enable USB CDC ACM logging for debugging | n       |
 | `CONFIG_ZMK_LOG_LEVEL`   | int  | Log level for ZMK debug messages         | 4       |
 
-### Double Tap To Bootloader
-
-| Config                                     | Type | Description                                                         | Default                     |
-| ------------------------------------------ | ---- | ------------------------------------------------------------------- | --------------------------- |
-| `CONFIG_ZMK_DBL_TAP_BOOTLOADER`            | bool | Enable the double-tap to enter bootloader functionality             | y if STM32 or RP2040/RP2350 |
-| `CONFIG_ZMK_DBL_TAP_BOOTLOADER_TIMEOUT_MS` | int  | Duration (in ms) to wait for a second reset to enter the bootloader | 500                         |
-
 ## Snippets
 
 :::danger

docs/sidebars.js

@@ -122,6 +122,7 @@ module.exports = {
         "config/battery",
         "config/behaviors",
         "config/bluetooth",
+        "config/bootloader",
         "config/combos",
         "config/displays",
         "config/encoders",