stmhal: Clean up reset/soft-reset code; fix bug init'ing VCP exc.

Make a clearer distinction between init functions that must be done
before any scripts can run (xxx_init0) and those that can be safely
deferred (xxx_init).

Fix bug initialising USB VCP exception.  Addresses issue #788.

Re-order some init function to improve reliability of
reset/soft-reset.

stmhal/extint.c

@@ -346,7 +346,7 @@ const mp_obj_type_t extint_type = {
     .locals_dict = (mp_obj_t)&extint_locals_dict,
 };
 
-void extint_init(void) {
+void extint_init0(void) {
     for (extint_vector_t *v = extint_vector; v < &extint_vector[EXTI_NUM_VECTORS]; v++) {
         v->callback_obj = mp_const_none;
         v->param = NULL;

stmhal/extint.h

@@ -46,7 +46,7 @@
 #define EXTI_TRIGGER_FALLING        (offsetof(EXTI_TypeDef, FTSR))
 #define EXTI_TRIGGER_RISING_FALLING (EXTI_TRIGGER_RISING + EXTI_TRIGGER_FALLING)  // just different from RISING or FALLING
 
-void extint_init(void);
+void extint_init0(void);
 
 uint extint_register(mp_obj_t pin_obj, uint32_t mode, uint32_t pull, mp_obj_t callback_obj, bool override_callback_obj, void *param);
 

stmhal/main.c

@@ -333,11 +333,26 @@ soft_reset:
     pyb_stdio_uart = NULL;
 #endif
 
-    readline_init();
-    pin_init();
-    extint_init();
+    // Initialise low-level sub-systems.  Here we need to very basic things like
+    // zeroing out memory and resetting any of the sub-systems.  Following this
+    // we can run Python scripts (eg boot.py), but anything that is configurable
+    // by boot.py must be set after boot.py is run.
 
-    // local filesystem init
+    readline_init0();
+    pin_init0();
+    extint_init0();
+    timer_init0();
+
+#if MICROPY_HW_ENABLE_RNG
+    rng_init0();
+#endif
+
+    i2c_init0();
+    spi_init0();
+    pyb_usb_init0();
+
+    // Initialise the local flash filesystem.
+    // Create it if needed, and mount in on /flash.
     {
         // try to mount the flash
         FRESULT res = f_mount(&fatfs0, "/flash", 1);
@@ -383,7 +398,11 @@ soft_reset:
         }
     }
 
-    // make sure we have a /flash/boot.py
+    // The current directory is used as the boot up directory.
+    // It is set to the internal flash filesystem by default.
+    f_chdrive("/flash");
+
+    // Make sure we have a /flash/boot.py.  Create it if needed.
     {
         FILINFO fno;
 #if _USE_LFN
@@ -419,9 +438,6 @@ soft_reset:
         }
     }
 
-    // root device defaults to internal flash filesystem
-    f_chdrive("/flash");
-
 #if defined(USE_DEVICE_MODE)
     usb_storage_medium_t usb_medium = USB_STORAGE_MEDIUM_FLASH;
 #endif
@@ -433,7 +449,7 @@ soft_reset:
         if (res != FR_OK) {
             printf("[SD] could not mount SD card\n");
         } else {
-            // use SD card as root device
+            // use SD card as current directory
             f_chdrive("/sd");
 
             // TODO these should go before the /flash entries in the path
@@ -448,9 +464,6 @@ soft_reset:
             }
         }
     }
-#else
-    // Get rid of compiler warning if no SDCARD is configured.
-    (void)first_soft_reset;
 #endif
 
     // run boot.py, if it exists
@@ -469,6 +482,10 @@ soft_reset:
     led_state(3, 0);
     led_state(4, 0);
 
+    // Now we initialise sub-systems that need configuration from boot.py,
+    // or whose initialisation can be safely deferred until after running
+    // boot.py.
+
 #if defined(USE_HOST_MODE)
     // USB host
     pyb_usb_host_init();
@@ -487,15 +504,6 @@ soft_reset:
     }
 #endif
 
-    timer_init0();
-
-#if MICROPY_HW_ENABLE_RNG
-    rng_init0();
-#endif
-
-    i2c_init0();
-    spi_init0();
-
 #if MICROPY_HW_HAS_MMA7660
     // MMA accel: init and reset
     accel_init();
@@ -511,7 +519,15 @@ soft_reset:
     dac_init();
 #endif
 
-    // now that everything is initialised, run main script
+#if MICROPY_HW_ENABLE_CC3K
+    // wifi using the CC3000 driver
+    pyb_wlan_init();
+    pyb_wlan_start();
+#endif
+
+    // At this point everything is fully configured and initialised.
+
+    // Run the main script from the current directory.
     if (reset_mode == 1 && pyexec_mode_kind == PYEXEC_MODE_FRIENDLY_REPL) {
         const char *main_py;
         if (pyb_config_main == MP_OBJ_NULL) {
@@ -527,14 +543,8 @@ soft_reset:
         }
     }
 
-#if MICROPY_HW_ENABLE_CC3K
-    // wifi using the CC3000 driver
-    pyb_wlan_init();
-    pyb_wlan_start();
-#endif
-
-    // enter REPL
-    // REPL mode can change, or it can request a soft reset
+    // Main script is finished, so now go into REPL mode.
+    // The REPL mode can change, or it can request a soft reset.
     for (;;) {
         if (pyexec_mode_kind == PYEXEC_MODE_RAW_REPL) {
             if (pyexec_raw_repl() != 0) {
@@ -547,6 +557,8 @@ soft_reset:
         }
     }
 
+    // soft reset
+
     printf("PYB: sync filesystems\n");
     storage_flush();
 

stmhal/pin.c

@@ -98,7 +98,7 @@ STATIC mp_obj_t pin_class_mapper;
 STATIC mp_obj_t pin_class_map_dict;
 STATIC bool pin_class_debug;
 
-void pin_init(void) {
+void pin_init0(void) {
     pin_class_mapper = mp_const_none;
     pin_class_map_dict = mp_const_none;
     pin_class_debug = false;

stmhal/pin.h

@@ -78,7 +78,7 @@ typedef struct {
 extern const pin_named_pins_obj_t pin_board_pins_obj;
 extern const pin_named_pins_obj_t pin_cpu_pins_obj;
 
-void pin_init(void);
+void pin_init0(void);
 const pin_obj_t *pin_find(mp_obj_t user_obj);
 const pin_obj_t *pin_find_named_pin(const pin_named_pin_t *pins, const char *name);
 const pin_af_obj_t *pin_find_af(const pin_obj_t *pin, uint8_t fn, uint8_t unit, uint8_t pin_type);

stmhal/readline.c

@@ -52,7 +52,7 @@ static const char *readline_hist[READLINE_HIST_SIZE] = {NULL, NULL, NULL, NULL,
 
 enum { ESEQ_NONE, ESEQ_ESC, ESEQ_ESC_BRACKET, ESEQ_ESC_BRACKET_DIGIT, ESEQ_ESC_O };
 
-void readline_init(void) {
+void readline_init0(void) {
     memset(readline_hist, 0, READLINE_HIST_SIZE * sizeof(const char*));
 }
 

stmhal/readline.h

@@ -24,5 +24,5 @@
  * THE SOFTWARE.
  */
 
-void readline_init(void);
+void readline_init0(void);
 int readline(vstr_t *line, const char *prompt);

stmhal/usb.c

@@ -45,8 +45,14 @@
 USBD_HandleTypeDef hUSBDDevice;
 #endif
 
-static int dev_is_enabled = 0;
-mp_obj_t mp_const_vcp_interrupt = MP_OBJ_NULL;
+STATIC int dev_is_enabled = 0;
+STATIC mp_obj_t mp_const_vcp_interrupt = MP_OBJ_NULL;
+
+void pyb_usb_init0(void) {
+    // create an exception object for interrupting by VCP
+    mp_const_vcp_interrupt = mp_obj_new_exception_msg(&mp_type_OSError, "VCPInterrupt");
+    USBD_CDC_SetInterrupt(VCP_CHAR_NONE, mp_const_vcp_interrupt);
+}
 
 void pyb_usb_dev_init(usb_device_mode_t mode, usb_storage_medium_t medium) {
 #ifdef USE_DEVICE_MODE
@@ -72,9 +78,6 @@ void pyb_usb_dev_init(usb_device_mode_t mode, usb_storage_medium_t medium) {
         USBD_Start(&hUSBDDevice);
     }
     dev_is_enabled = 1;
-
-    // create an exception object for interrupting by VCP
-    mp_const_vcp_interrupt = mp_obj_new_exception_msg(&mp_type_OSError, "VCPInterrupt");
 #endif
 }
 

stmhal/usb.h

@@ -43,6 +43,7 @@ typedef enum {
 
 const mp_obj_type_t pyb_usb_vcp_type;
 
+void pyb_usb_init0(void);
 void pyb_usb_dev_init(usb_device_mode_t mode, usb_storage_medium_t medium);
 void pyb_usb_dev_stop(void);
 bool usb_vcp_is_enabled(void);