Add graceful shutdown support

src/hal/interface/syslink.h

@@ -64,8 +64,10 @@
 #define SYSLINK_OW_READ     0x22
 #define SYSLINK_OW_WRITE    0x23
 
-#define SYSLINK_SYS_GROUP        0x30
-#define SYSLINK_SYS_NRF_VERSION  0x30
+#define SYSLINK_SYS_GROUP            0x30
+#define SYSLINK_SYS_NRF_VERSION      0x30
+#define SYSLINK_SYS_SHUTDOWN_REQUEST 0x31
+#define SYSLINK_SYS_SHUTDOWN_ACK     0x32
 
 typedef struct _SyslinkPacket
 {

src/modules/interface/system.h

@@ -30,6 +30,8 @@
 #include <stdbool.h>
 #include <stdint.h>
 
+typedef void (*graceful_shutdown_callback_t)();
+
 void systemInit(void);
 bool systemTest(void);
 
@@ -45,4 +47,6 @@ void systemRequestShutdown();
 void systemRequestNRFVersion();
 void systemSyslinkReceive();
 
+bool systemRegisterGracefulShutdownCallback(graceful_shutdown_callback_t cb);
+
 #endif //__SYSTEM_H__

src/modules/src/system.c

@@ -352,17 +352,70 @@ void systemRequestNRFVersion()
   syslinkSendPacket(&slp);
 }
 
+/*
+ * When a module wants to register a callback to be called on shutdown they
+ * call systemRegisterGracefulShutdownCallback(graceful_shutdown_callback_t),
+ * with a function they which to be run at shutdown. We currently support
+ * GRACEFUL_SHUTDOWN_MAX_CALLBACKS number of callbacks to be registred.
+ */
+#define GRACEFUL_SHUTDOWN_MAX_CALLBACKS 5
+static uint8_t graceful_shutdown_callbacks_index;
+static graceful_shutdown_callback_t graceful_shutdown_callbacks[GRACEFUL_SHUTDOWN_MAX_CALLBACKS];
+
+/*
+ * Please take care in your callback, do not take to long time the nrf
+ * will not wait for you, it will shutdown.
+ */
+bool systemRegisterGracefulShutdownCallback(graceful_shutdown_callback_t cb)
+{
+  // To many registered allready! Increase limit if you think you are important
+  // enough!
+  if (graceful_shutdown_callbacks_index >= GRACEFUL_SHUTDOWN_MAX_CALLBACKS) {
+    return false;
+  }
+
+  graceful_shutdown_callbacks[graceful_shutdown_callbacks_index] = cb;
+  graceful_shutdown_callbacks_index += 1;
+
+  return true;
+}
+
+/*
+ * Iterate through all registered shutdown callbacks and call them one after
+ * the other, when all is done, send the ACK back to nrf to allow power off.
+ */
+void systemGracefulShutdown()
+{
+  for (int i = 0; i < graceful_shutdown_callbacks_index; i++) {
+    graceful_shutdown_callback_t callback = graceful_shutdown_callbacks[i];
+
+    callback();
+  }
+
+  SyslinkPacket slp = {
+    .type = SYSLINK_SYS_SHUTDOWN_ACK,
+  };
+
+  syslinkSendPacket(&slp);
+}
+
 void systemSyslinkReceive(SyslinkPacket *slp)
 {
-  if (slp->type == SYSLINK_SYS_NRF_VERSION)
+  switch (slp->type)
   {
+  case SYSLINK_SYS_NRF_VERSION:{
     size_t len = slp->length - 2;
 
     if (sizeof(nrf_version) - 1 <=  len) {
       len = sizeof(nrf_version) - 1;
     }
     memcpy(&nrf_version, &slp->data[0], len);
     DEBUG_PRINT("NRF51 version: %s\n", nrf_version);
+  } break;
+
+  case SYSLINK_SYS_SHUTDOWN_REQUEST:
+    systemGracefulShutdown();
+    break;
   }
 }