extmod/fsusermount: Introduce separate mkfs() function.

Per the previously discussed plan. mount() still stays backward-compatible,
and new mkfs() is rought and takes more args than needed. But is a step
in a forward direction.

extmod/fsusermount.c

@@ -32,7 +32,7 @@
 #include "lib/fatfs/ff.h"
 #include "fsusermount.h"
 
-STATIC mp_obj_t pyb_mount(mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+STATIC mp_obj_t fatfs_mount_mkfs(mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args, bool mkfs) {
     static const mp_arg_t allowed_args[] = {
         { MP_QSTR_readonly, MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} },
         { MP_QSTR_mkfs, MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} },
@@ -85,15 +85,28 @@ STATIC mp_obj_t pyb_mount(mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *
             vfs->writeblocks[0] = MP_OBJ_NULL;
         }
 
-        // mount the block device
-        FRESULT res = f_mount(&vfs->fatfs, vfs->str, 1);
+        // mount the block device (if mkfs, only pre-mount)
+        FRESULT res = f_mount(&vfs->fatfs, vfs->str, !mkfs);
         // check the result
         if (res == FR_OK) {
+            if (mkfs) {
+                goto mkfs;
+            }
         } else if (res == FR_NO_FILESYSTEM && args[1].u_bool) {
+mkfs:
             res = f_mkfs(vfs->str, 1, 0);
             if (res != FR_OK) {
+mkfs_error:
                 nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, "can't mkfs"));
             }
+            if (mkfs) {
+                // If requested to only mkfs, unmount pre-mounted device
+                res = f_mount(NULL, vfs->str, 0);
+                if (res != FR_OK) {
+                    goto mkfs_error;
+                }
+                MP_STATE_PORT(fs_user_mount) = NULL;
+            }
         } else {
             nlr_raise(mp_obj_new_exception_msg(&mp_type_OSError, "can't mount"));
         }
@@ -112,6 +125,15 @@ STATIC mp_obj_t pyb_mount(mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *
     }
     return mp_const_none;
 }
-MP_DEFINE_CONST_FUN_OBJ_KW(pyb_mount_obj, 2, pyb_mount);
+
+STATIC mp_obj_t fatfs_mount(mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    return fatfs_mount_mkfs(n_args, pos_args, kw_args, false);
+}
+MP_DEFINE_CONST_FUN_OBJ_KW(fsuser_mount_obj, 2, fatfs_mount);
+
+STATIC mp_obj_t fatfs_mkfs(mp_uint_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
+    return fatfs_mount_mkfs(n_args, pos_args, kw_args, true);
+}
+MP_DEFINE_CONST_FUN_OBJ_KW(fsuser_mkfs_obj, 2, fatfs_mkfs);
 
 #endif // MICROPY_FSUSERMOUNT

extmod/fsusermount.h

@@ -34,4 +34,5 @@ typedef struct _fs_user_mount_t {
     FATFS fatfs;
 } fs_user_mount_t;
 
-MP_DECLARE_CONST_FUN_OBJ(pyb_mount_obj);
+MP_DECLARE_CONST_FUN_OBJ(fsuser_mount_obj);
+MP_DECLARE_CONST_FUN_OBJ(fsuser_mkfs_obj);

stmhal/modpyb.c

@@ -61,6 +61,7 @@
 #include "usb.h"
 #include "portmodules.h"
 #include "modmachine.h"
+#include "extmod/fsusermount.h"
 
 /// \function millis()
 /// Returns the number of milliseconds since the board was last reset.
@@ -164,7 +165,7 @@ STATIC const mp_map_elem_t pyb_module_globals_table[] = {
     { MP_OBJ_NEW_QSTR(MP_QSTR_delay), (mp_obj_t)&time_sleep_ms_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_udelay), (mp_obj_t)&time_sleep_us_obj },
     { MP_OBJ_NEW_QSTR(MP_QSTR_sync), (mp_obj_t)&mod_os_sync_obj },
-    { MP_OBJ_NEW_QSTR(MP_QSTR_mount), (mp_obj_t)&pyb_mount_obj },
+    { MP_OBJ_NEW_QSTR(MP_QSTR_mount), (mp_obj_t)&fsuser_mount_obj },
 
     { MP_OBJ_NEW_QSTR(MP_QSTR_Timer), (mp_obj_t)&pyb_timer_type },