Add support for reboot on not ok for stm32 platform

Adds the cmake configuration option `AVM_CONFIG_REBOOT_ON_NOT_OK` to allow the
automatic rebooting of the device if the user application exits with any return
value other than `ok`.

Signed-off-by: Winford <[email protected]>

CHANGELOG.md

@@ -6,6 +6,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [0.6.0-alpha.2] - Unreleased
 
+### Added
+
+- Added cmake configuration option `AVM_CONFIG_REBOOT_ON_NOT_OK` for STM32
+
 ### Fixed
 
 - Fixed a bug where guards would raise exceptions instead of just being false

doc/src/build-instructions.md

@@ -551,6 +551,9 @@ is 8N1 with no flow control.
 
 > If building for a different target USART and gpio pins may need to be adjusted in `main.c`.
 
+### Configuring for "deployment"
+After your application has been tested (_and debugged_) and is ready to put into active use you may want to tune the build of AtomVM.  For instance disabling logging with `-DAVM_LOG_DISABLE=on` as a `cmake` configuration option may result in slightly better performance. This will have no affect on the console output of your application, just disable low level log messages from the AtomVM system. You may also want to enabling automatic reboot in the case that your application ever exits with a return other than `ok`. This can be enabled with the `cmake` option `-DAVM_CONFIG_REBOOT_ON_NOT_OK=on`.
+
 ## Building for Raspberry Pi Pico
 
 ### Prerequisites

src/platforms/stm32/CMakeLists.txt

@@ -32,6 +32,7 @@ option(AVM_NEWLIB_NANO "Use 'nano' newlib. Saves 46kB, no `long long` support" O
 option(AVM_LOG_DISABLE "Disable log output" OFF)
 option(AVM_ENABLE_LOG_COLOR "Use color log output" OFF)
 option(AVM_ENABLE_LOG_LINES "Include source and line info for all enbled levels" OFF)
+option(AVM_CONFIG_REBOOT_ON_NOT_OK "Reboot when application exits with non 'ok' return" OFF)
 
 set(AVM_DISABLE_SMP ON FORCE)
 
@@ -40,7 +41,11 @@ if (AVM_NEWLIB_NANO)
     set(AVM_LOG_DISABLE ON FORCE)
 endif()
 
-# Configure logging
+if (AVM_CONFIG_REBOOT_ON_NOT_OK)
+    add_compile_definitions(CONFIG_REBOOT_ON_NOT_OK)
+endif()
+
+    # Configure logging
 if (AVM_LOG_DISABLE)
     add_compile_definitions(AVM_LOG_DISABLE)
 elseif (AVM_LOG_LEVEL_MAX)

src/platforms/stm32/src/main.c

@@ -23,14 +23,17 @@
 #include <stdio.h>
 #include <unistd.h>
 
+#include <libopencm3/cm3/cortex.h>
 #include <libopencm3/cm3/nvic.h>
+#include <libopencm3/cm3/scb.h>
 #include <libopencm3/cm3/systick.h>
 #include <libopencm3/stm32/gpio.h>
 #include <libopencm3/stm32/rcc.h>
 #include <libopencm3/stm32/usart.h>
 
 #include <avmpack.h>
 #include <context.h>
+#include <defaultatoms.h>
 #include <globalcontext.h>
 #include <module.h>
 #include <utils.h>
@@ -146,7 +149,8 @@ int _kill(pid_t pid, int sig)
 }
 
 // Redefine weak linked while(1) loop from libopencm3/cm3/nvic.h.
-void hard_fault_handler() {
+void hard_fault_handler()
+{
     fprintf(stderr, "\nHard Fault detected!\n");
     AVM_ABORT();
 }
@@ -197,10 +201,31 @@ int main()
 
     AVM_LOGI(TAG, "Starting: %s...\n", startup_module_name);
     context_execute_loop(ctx, mod, "start", 0);
-    AVM_LOGI(TAG, "Return value: %lx", (long) term_to_int32(ctx->x[0]));
 
-    while (1)
-        ;
+    term ret_value = ctx->x[0];
+    char *ret_atom_string = interop_atom_to_string(ctx, ret_value);
+    if (ret_atom_string != NULL) {
+        AVM_LOGI(TAG, "Exited with return: %s", ret_atom_string);
+    } else {
+        AVM_LOGI(TAG, "Exited with return value: %lx", (long) term_to_int32(ret_value));
+    }
 
+    bool reboot_on_not_ok =
+#if defined(CONFIG_REBOOT_ON_NOT_OK)
+        CONFIG_REBOOT_ON_NOT_OK ? true : false;
+#else
+        false;
+#endif
+    if (reboot_on_not_ok && ret_value != OK_ATOM) {
+        AVM_LOGE(TAG, "AtomVM application terminated with non-ok return value.  Rebooting ...");
+        scb_reset_system();
+    } else {
+        AVM_LOGI(TAG, "AtomVM application terminated.  Going to sleep forever ...");
+        // Disable all interrupts
+        cm_disable_interrupts();
+        while (1) {
+            ;
+        }
+    }
     return 0;
 }