extmod/modvfs: Add vfs.rom_ioctl function and its ioctl constants.

dpgeorge · dpgeorge · commit 89e6c58c8007 · 2025-03-06T12:52:35.000+11:00
This is a generic interface to allow querying and modifying the read-only
memory area of a device, if it has such an area.

Signed-off-by: Damien George &lt;damien@micropython.org&gt;
diff --git a/extmod/modvfs.c b/extmod/modvfs.c
@@ -38,11 +38,18 @@
 #error "MICROPY_PY_VFS requires MICROPY_VFS"
 #endif
 
+#if MICROPY_VFS_ROM_IOCTL
+static MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(mp_vfs_rom_ioctl_obj, 1, 4, mp_vfs_rom_ioctl);
+#endif
+
 static const mp_rom_map_elem_t vfs_module_globals_table[] = {
     { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_vfs) },
 
     { MP_ROM_QSTR(MP_QSTR_mount), MP_ROM_PTR(&mp_vfs_mount_obj) },
     { MP_ROM_QSTR(MP_QSTR_umount), MP_ROM_PTR(&mp_vfs_umount_obj) },
+    #if MICROPY_VFS_ROM_IOCTL
+    { MP_ROM_QSTR(MP_QSTR_rom_ioctl), MP_ROM_PTR(&mp_vfs_rom_ioctl_obj) },
+    #endif
     #if MICROPY_VFS_FAT
     { MP_ROM_QSTR(MP_QSTR_VfsFat), MP_ROM_PTR(&mp_fat_vfs_type) },
     #endif
diff --git a/extmod/vfs.h b/extmod/vfs.h
@@ -52,6 +52,13 @@
 #define MP_BLOCKDEV_IOCTL_BLOCK_SIZE    (5)
 #define MP_BLOCKDEV_IOCTL_BLOCK_ERASE   (6)
 
+// Constants for vfs.rom_ioctl() function.
+#define MP_VFS_ROM_IOCTL_GET_NUMBER_OF_SEGMENTS     (1) // rom_ioctl(1)
+#define MP_VFS_ROM_IOCTL_GET_SEGMENT                (2) // rom_ioctl(2, <id>)
+#define MP_VFS_ROM_IOCTL_WRITE_PREPARE              (3) // rom_ioctl(3, <id>, <len>)
+#define MP_VFS_ROM_IOCTL_WRITE                      (4) // rom_ioctl(4, <id>, <offset>, <buf>)
+#define MP_VFS_ROM_IOCTL_WRITE_COMPLETE             (5) // rom_ioctl(5, <id>)
+
 // At the moment the VFS protocol just has import_stat, but could be extended to other methods
 typedef struct _mp_vfs_proto_t {
     mp_import_stat_t (*import_stat)(void *self, const char *path);
@@ -122,4 +129,12 @@ MP_DECLARE_CONST_FUN_OBJ_1(mp_vfs_rmdir_obj);
 MP_DECLARE_CONST_FUN_OBJ_1(mp_vfs_stat_obj);
 MP_DECLARE_CONST_FUN_OBJ_1(mp_vfs_statvfs_obj);
 
+#if MICROPY_VFS_ROM_IOCTL
+// When MICROPY_VFS_ROM_IOCTL is enabled a port must define the following function.
+// This is a generic interface to allow querying and modifying the user-accessible,
+// read-only memory area of a device, if it is configured with such an area.
+// Supported ioctl commands are given by MP_VFS_ROM_IOCTL_xxx.
+mp_obj_t mp_vfs_rom_ioctl(size_t n_args, const mp_obj_t *args);
+#endif
+
 #endif // MICROPY_INCLUDED_EXTMOD_VFS_H
diff --git a/ports/qemu/mpconfigport.h b/ports/qemu/mpconfigport.h
@@ -64,6 +64,7 @@
 #define MICROPY_PY_MACHINE_PIN_BASE (1)
 #define MICROPY_VFS                 (1)
 #define MICROPY_VFS_ROM             (1)
+#define MICROPY_VFS_ROM_IOCTL       (0)
 
 // type definitions for the specific machine
 
diff --git a/ports/unix/variants/mpconfigvariant_common.h b/ports/unix/variants/mpconfigvariant_common.h
@@ -123,3 +123,4 @@
 #define MICROPY_PY_MACHINE_PIN_BASE    (1)
 
 #define MICROPY_VFS_ROM                (1)
+#define MICROPY_VFS_ROM_IOCTL          (0)
diff --git a/py/mpconfig.h b/py/mpconfig.h
@@ -1006,6 +1006,11 @@ typedef double mp_float_t;
 #define MICROPY_VFS_WRITABLE (1)
 #endif
 
+// Whether to enable the mp_vfs_rom_ioctl C function, and vfs.rom_ioctl Python function
+#ifndef MICROPY_VFS_ROM_IOCTL
+#define MICROPY_VFS_ROM_IOCTL (MICROPY_VFS_ROM)
+#endif
+
 // Support for VFS POSIX component, to mount a POSIX filesystem within VFS
 #ifndef MICROPY_VFS_POSIX
 #define MICROPY_VFS_POSIX (0)

Original file line number	Diff line number	Diff line change
`@@ -123,3 +123,4 @@`
`123`	`123`	`#define MICROPY_PY_MACHINE_PIN_BASE (1)`
`124`	`124`
`125`	`125`	`#define MICROPY_VFS_ROM (1)`
	`126`	`+#define MICROPY_VFS_ROM_IOCTL (0)`