extmod/fsusermount: Change block protocol to support ioctl method.

The new block protocol is:
- readblocks(self, n, buf)
- writeblocks(self, n, buf)
- ioctl(self, cmd, arg)

The new ioctl method handles the old sync and count methods, as well as
a new "get sector size" method.

The old protocol is still supported, and used if the device doesn't have
the ioctl method.

1 files changed, 9 insertions, 2 deletions

diff --git a/extmod/fsusermount.h b/extmod/fsusermount.h
index c141ecb99..53442a368 100644
--- a/extmod/fsusermount.h
+++ b/extmod/fsusermount.h
@@ -29,8 +29,15 @@ typedef struct _fs_user_mount_t {
     mp_uint_t len;
     mp_obj_t readblocks[4];
     mp_obj_t writeblocks[4];
-    mp_obj_t sync[2];
-    mp_obj_t count[2];
+    // new protocol uses just ioctl, old uses sync (optional) and count
+    // if ioctl[3]=count[1]=MP_OBJ_SENTINEL then we have the new protocol, else old
+    union {
+        mp_obj_t ioctl[4];
+        struct {
+            mp_obj_t sync[2];
+            mp_obj_t count[2];
+        } old;
+    } u;
     FATFS fatfs;
 } fs_user_mount_t;