HAL_ChibiOS: fixed fallback to microSD for storage

this is used when FRAM fails on a board with microSD support. The
double init caused the validate() in the FATFS code to fail

libraries/AP_HAL_ChibiOS/Storage.cpp

@@ -72,7 +72,7 @@ void Storage::_storage_open(void)
     _flash_load();
 #elif defined(USE_POSIX)
     // allow for fallback to microSD based storage
-    sdcard_init();
+    sdcard_retry();
     
     log_fd = open(HAL_STORAGE_FILE, O_RDWR|O_CREAT);
     if (log_fd == -1) {
@@ -110,7 +110,7 @@ void Storage::_save_backup(void)
 {
 #ifdef USE_POSIX
     // allow for fallback to microSD based storage
-    sdcard_init();
+    sdcard_retry();
     int fd = open(HAL_STORAGE_BACKUP_FILE, O_WRONLY|O_CREAT|O_TRUNC);
     if (fd != -1) {
         write(fd, _buffer, CH_STORAGE_SIZE);

libraries/AP_HAL_ChibiOS/Util.cpp

@@ -258,6 +258,6 @@ bool Util::get_system_id(char buf[40])
  */
 bool Util::fs_init(void)
 {
-    return sdcard_init();
+    return sdcard_retry();
 }
 #endif

libraries/AP_HAL_ChibiOS/sdcard.cpp

@@ -95,6 +95,7 @@ bool sdcard_init()
     device = AP_HAL::get_HAL().spi->get_device("sdcard");
     if (!device) {
         printf("No sdcard SPI device found\n");
+        sdcard_running = false;
         sem.give();
         return false;
     }
@@ -131,8 +132,8 @@ bool sdcard_init()
         sem.give();
         return true;
     }
-    sdcard_running = false;
 #endif
+    sdcard_running = false;
     sem.give();
 #endif
     return false;
@@ -162,13 +163,15 @@ void sdcard_stop(void)
 #endif
 }
 
-void sdcard_retry(void)
+bool sdcard_retry(void)
 {
 #ifdef USE_POSIX
     if (!sdcard_running) {
         sdcard_init();
     }
+    return sdcard_running;
 #endif
+    return false;
 }
 
 #if HAL_USE_MMC_SPI

libraries/AP_HAL_ChibiOS/sdcard.h

@@ -17,4 +17,4 @@
 
 bool sdcard_init();
 void sdcard_stop();
-void sdcard_retry();
+bool sdcard_retry();