stm32/mboot: Add support for a raw filesystem.

This is enabled by default if MBOOT_FSLOAD is enabled, although a board
can explicitly disable it by `#define MBOOT_VFS_RAW (0)`.

Signed-off-by: Damien George <damien@micropython.org>

7 files changed, 232 insertions, 29 deletions

diff --git a/ports/stm32/mboot/Makefile b/ports/stm32/mboot/Makefile
index 389f9f5d0..07053b329 100755
--- a/ports/stm32/mboot/Makefile
+++ b/ports/stm32/mboot/Makefile
@@ -120,6 +120,7 @@ SRC_C += \
 	ui.c \
 	vfs_fat.c \
 	vfs_lfs.c \
+	vfs_raw.c \
 	drivers/bus/softspi.c \
 	drivers/bus/softqspi.c \
 	drivers/memory/spiflash.c \
diff --git a/ports/stm32/mboot/README.md b/ports/stm32/mboot/README.md
index 73e32fced..221e3a7c3 100644
--- a/ports/stm32/mboot/README.md
+++ b/ports/stm32/mboot/README.md
@@ -71,13 +71,23 @@ How to use
     #define MBOOT_FSLOAD (1)
 
    and then enable one or more of the following depending on what filesystem
-   support is required in Mboot (note that the FAT driver is read-only and
-   quite compact, but littlefs supports both read and write so is rather
-   large):
+   support is required in Mboot:
 
     #define MBOOT_VFS_FAT (1)
     #define MBOOT_VFS_LFS1 (1)
     #define MBOOT_VFS_LFS2 (1)
+    #define MBOOT_VFS_RAW (1)
+
+   Note that the FAT and LFS2 drivers are read-only and quite compact, but
+   LFS1 supports both read and write so is rather large.
+
+   The raw filesystem type is enabled by default and is a flat section of
+   storage containing a single file without any metadata.  The raw filesystem
+   can either be one regoin, or split over two separate, contiguous regions.
+   The latter is useful for wear levelling: given a chunk of flash, write the
+   firmware starting at a random block within that chunk and wrap around to
+   the beginning of the chunk when the end is reached.  Then use a split
+   raw filesystem to inform mboot of this wrapping.
 
 2. Build the board's main application firmware as usual.
 
diff --git a/ports/stm32/mboot/fsload.c b/ports/stm32/mboot/fsload.c
index abc3514ed..83905eb49 100644
--- a/ports/stm32/mboot/fsload.c
+++ b/ports/stm32/mboot/fsload.c
@@ -39,7 +39,7 @@
 
 #if MBOOT_FSLOAD
 
-#if !(MBOOT_VFS_FAT || MBOOT_VFS_LFS1 || MBOOT_VFS_LFS2)
+#if !(MBOOT_VFS_FAT || MBOOT_VFS_LFS1 || MBOOT_VFS_LFS2 || MBOOT_VFS_RAW)
 #error Must enable at least one VFS component
 #endif
 
@@ -234,28 +234,51 @@ int fsload_process(void) {
             // End of elements.
             return -MBOOT_ERRNO_FSLOAD_NO_MOUNT;
         }
+
+        // Extract element arguments based on the element length:
+        // - 10 bytes: mount_point fs_type uint32_t uint32_t
+        // - 14 bytes: mount_point fs_type uint32_t uint32_t uint32_t
+        // - 18 bytes: mount_point fs_type uint32_t uint32_t uint32_t uint32_t
+        // - 22 bytes: mount_point fs_type uint64_t uint64_t uint32_t
+        // - 34 bytes: mount_point fs_type uint64_t uint64_t uint64_t uint64_t
         mboot_addr_t base_addr;
         mboot_addr_t byte_len;
-        uint32_t block_size = MBOOT_FSLOAD_DEFAULT_BLOCK_SIZE;
-        if (elem[-1] == 10 || elem[-1] == 14) {
+        mboot_addr_t arg2 = 0;
+        mboot_addr_t arg3 = 0;
+        (void)arg2;
+        (void)arg3;
+        uint8_t elem_len = elem[-1];
+        if (elem_len == 10 || elem_len == 14 || elem_len == 18) {
             // 32-bit base and length given, extract them.
             base_addr = get_le32(&elem[2]);
             byte_len = get_le32(&elem[6]);
-            if (elem[-1] == 14) {
-                // Block size given, extract it.
-                block_size = get_le32(&elem[10]);
+            if (elem_len >= 14) {
+                // Argument 2 given, extract it.
+                arg2 = get_le32(&elem[10]);
+                if (elem_len == 18) {
+                    // Argument 3 given, extract it.
+                    arg3 = get_le32(&elem[14]);
+                }
             }
         #if MBOOT_ADDRESS_SPACE_64BIT
-        } else if (elem[-1] == 22) {
-            // 64-bit base and length given, and block size, so extract them.
+        } else if (elem_len == 22 || elem_len == 34) {
+            // 64-bit base and length given, so extract them.
             base_addr = get_le64(&elem[2]);
             byte_len = get_le64(&elem[10]);
-            block_size = get_le32(&elem[18]);
+            if (elem_len == 22) {
+                // 32-bit argument 2 given, extract it.
+                arg2 = get_le32(&elem[18]);
+            } else {
+                // 64-bit argument 2 and 3 given, extract them.
+                arg2 = get_le64(&elem[18]);
+                arg3 = get_le64(&elem[26]);
+            }
         #endif
         } else {
             // Invalid MOUNT element.
             return -MBOOT_ERRNO_FSLOAD_INVALID_MOUNT;
         }
+
         if (elem[0] == mount_point) {
             int ret;
             union {
@@ -268,27 +291,43 @@ int fsload_process(void) {
                 #if MBOOT_VFS_LFS2
                 vfs_lfs2_context_t lfs2;
                 #endif
+                #if MBOOT_VFS_RAW
+                vfs_raw_context_t raw;
+                #endif
             } ctx;
             const stream_methods_t *methods;
             #if MBOOT_VFS_FAT
             if (elem[1] == ELEM_MOUNT_FAT) {
-                (void)block_size;
                 ret = vfs_fat_mount(&ctx.fat, base_addr, byte_len);
                 methods = &vfs_fat_stream_methods;
             } else
             #endif
             #if MBOOT_VFS_LFS1
             if (elem[1] == ELEM_MOUNT_LFS1) {
+                uint32_t block_size = arg2;
+                if (block_size == 0) {
+                    block_size = MBOOT_FSLOAD_DEFAULT_BLOCK_SIZE;
+                }
                 ret = vfs_lfs1_mount(&ctx.lfs1, base_addr, byte_len, block_size);
                 methods = &vfs_lfs1_stream_methods;
             } else
             #endif
             #if MBOOT_VFS_LFS2
             if (elem[1] == ELEM_MOUNT_LFS2) {
+                uint32_t block_size = arg2;
+                if (block_size == 0) {
+                    block_size = MBOOT_FSLOAD_DEFAULT_BLOCK_SIZE;
+                }
                 ret = vfs_lfs2_mount(&ctx.lfs2, base_addr, byte_len, block_size);
                 methods = &vfs_lfs2_stream_methods;
             } else
             #endif
+            #if MBOOT_VFS_RAW
+            if (elem[1] == ELEM_MOUNT_RAW) {
+                ret = vfs_raw_mount(&ctx.raw, base_addr, byte_len, arg2, arg3);
+                methods = &vfs_raw_stream_methods;
+            } else
+            #endif
             {
                 // Unknown filesystem type
                 return -MBOOT_ERRNO_FSLOAD_INVALID_MOUNT;
diff --git a/ports/stm32/mboot/fwupdate.py b/ports/stm32/mboot/fwupdate.py
index 47ceb19ba..8578ff4fc 100644
--- a/ports/stm32/mboot/fwupdate.py
+++ b/ports/stm32/mboot/fwupdate.py
@@ -9,6 +9,7 @@ import deflate, machine, stm
 VFS_FAT = 1
 VFS_LFS1 = 2
 VFS_LFS2 = 3
+VFS_RAW = 4
 
 # Constants for creating mboot elements.
 _ELEM_TYPE_END = const(1)
@@ -226,28 +227,45 @@ def _create_element(kind, body):
 
 
 def update_app_elements(
-    filename, fs_base, fs_len, fs_type=VFS_FAT, fs_blocksize=0, status_addr=None, addr_64bit=False
+    filename,
+    fs_base,
+    fs_len,
+    fs_type=VFS_FAT,
+    fs_blocksize=0,
+    status_addr=None,
+    addr_64bit=False,
+    *,
+    fs_base2=0,
+    fs_len2=0,
 ):
-    # Check firmware is of .dfu or .dfu.gz type
-    try:
-        with open(filename, "rb") as f:
-            hdr = deflate.DeflateIO(f, deflate.GZIP).read(6)
-    except Exception:
-        with open(filename, "rb") as f:
-            hdr = f.read(6)
-    if hdr != b"DfuSe\x01":
-        print("Firmware must be a .dfu(.gz) file.")
-        return ()
+    if fs_type != VFS_RAW:
+        # Check firmware is of .dfu or .dfu.gz type
+        try:
+            with open(filename, "rb") as f:
+                hdr = deflate.DeflateIO(f, deflate.GZIP).read(6)
+        except Exception:
+            with open(filename, "rb") as f:
+                hdr = f.read(6)
+        if hdr != b"DfuSe\x01":
+            print("Firmware must be a .dfu(.gz) file.")
+            return ()
 
     if fs_type in (VFS_LFS1, VFS_LFS2) and not fs_blocksize:
         raise Exception("littlefs requires fs_blocksize parameter")
 
     mount_point = 1
-    mount_encoding = "<BBQQL" if addr_64bit else "<BBLLL"
-    elems = _create_element(
-        _ELEM_TYPE_MOUNT,
-        struct.pack(mount_encoding, mount_point, fs_type, fs_base, fs_len, fs_blocksize),
-    )
+    if fs_type == VFS_RAW:
+        mount_encoding = "<BBQQQQ" if addr_64bit else "<BBLLLL"
+        elems = _create_element(
+            _ELEM_TYPE_MOUNT,
+            struct.pack(mount_encoding, mount_point, fs_type, fs_base, fs_len, fs_base2, fs_len2),
+        )
+    else:
+        mount_encoding = "<BBQQL" if addr_64bit else "<BBLLL"
+        elems = _create_element(
+            _ELEM_TYPE_MOUNT,
+            struct.pack(mount_encoding, mount_point, fs_type, fs_base, fs_len, fs_blocksize),
+        )
     elems += _create_element(
         _ELEM_TYPE_FSLOAD, struct.pack("<B", mount_point) + bytes(filename, "ascii")
     )
diff --git a/ports/stm32/mboot/mboot.h b/ports/stm32/mboot/mboot.h
index 2c4813332..1fabff008 100644
--- a/ports/stm32/mboot/mboot.h
+++ b/ports/stm32/mboot/mboot.h
@@ -92,6 +92,31 @@
 #define MBOOT_LED_STATE_LED2 (0x04)
 #define MBOOT_LED_STATE_LED3 (0x08)
 
+// Whether to support loading firmware from a filesystem.
+#ifndef MBOOT_FSLOAD
+#define MBOOT_FSLOAD (0)
+#endif
+
+// Whether to support FAT filesystems.
+#ifndef MBOOT_VFS_FAT
+#define MBOOT_VFS_FAT (0)
+#endif
+
+// Whether to support Littlefs v1 filesystems.
+#ifndef MBOOT_VFS_LFS1
+#define MBOOT_VFS_LFS1 (0)
+#endif
+
+// Whether to support Littlefs v2 filesystems.
+#ifndef MBOOT_VFS_LFS2
+#define MBOOT_VFS_LFS2 (0)
+#endif
+
+// Whether to support raw filesystems.
+#ifndef MBOOT_VFS_RAW
+#define MBOOT_VFS_RAW (MBOOT_FSLOAD)
+#endif
+
 // These enum values are passed as the first argument to mboot_state_change() to
 // notify of a change in state of the bootloader activity.  This function has a
 // default implementation in ui.c but can be overridden by a board.  Some states
@@ -158,6 +183,7 @@ enum {
     ELEM_MOUNT_FAT = 1,
     ELEM_MOUNT_LFS1,
     ELEM_MOUNT_LFS2,
+    ELEM_MOUNT_RAW,
 };
 
 // Configure the type used to hold an address in the mboot address space.
diff --git a/ports/stm32/mboot/vfs.h b/ports/stm32/mboot/vfs.h
index 53dac8800..a2e13b158 100644
--- a/ports/stm32/mboot/vfs.h
+++ b/ports/stm32/mboot/vfs.h
@@ -93,4 +93,22 @@ int vfs_lfs2_mount(vfs_lfs2_context_t *ctx, mboot_addr_t base_addr, mboot_addr_t
 
 #endif
 
+#if MBOOT_VFS_RAW
+
+// A raw VFS contains a contiguous, single file without any metadata.
+
+typedef struct _vfs_raw_context_t {
+    mboot_addr_t seg0_base_addr;
+    mboot_addr_t seg0_byte_len;
+    mboot_addr_t seg1_base_addr;
+    mboot_addr_t seg1_byte_len;
+    mboot_addr_t file_pos;
+} vfs_raw_context_t;
+
+extern const stream_methods_t vfs_raw_stream_methods;
+
+int vfs_raw_mount(vfs_raw_context_t *ctx, mboot_addr_t seg0_base_addr, mboot_addr_t seg0_byte_len, mboot_addr_t seg1_base_addr, mboot_addr_t seg1_byte_len);
+
+#endif
+
 #endif // MICROPY_INCLUDED_STM32_MBOOT_VFS_H
diff --git a/ports/stm32/mboot/vfs_raw.c b/ports/stm32/mboot/vfs_raw.c
new file mode 100644
index 000000000..05539c695
--- /dev/null
+++ b/ports/stm32/mboot/vfs_raw.c
@@ -0,0 +1,91 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2024 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "mboot.h"
+#include "vfs.h"
+
+#if MBOOT_FSLOAD && MBOOT_VFS_RAW
+
+#ifndef MIN
+#define MIN(x, y) ((x) < (y) ? (x) : (y))
+#endif
+
+int vfs_raw_mount(vfs_raw_context_t *ctx, mboot_addr_t seg0_base_addr, mboot_addr_t seg0_byte_len, mboot_addr_t seg1_base_addr, mboot_addr_t seg1_byte_len) {
+    ctx->seg0_base_addr = seg0_base_addr;
+    ctx->seg0_byte_len = seg0_byte_len;
+    ctx->seg1_base_addr = seg1_base_addr;
+    ctx->seg1_byte_len = seg1_byte_len;
+    return 0;
+}
+
+static int vfs_raw_stream_open(void *stream_in, const char *fname) {
+    vfs_raw_context_t *stream = stream_in;
+    (void)fname;
+    stream->file_pos = 0;
+    return 0;
+}
+
+static void vfs_raw_stream_close(void *stream_in) {
+    (void)stream_in;
+}
+
+static int vfs_raw_stream_read(void *stream_in, uint8_t *buf, size_t len) {
+    vfs_raw_context_t *stream = stream_in;
+    size_t orig_len = len;
+    while (len) {
+        mboot_addr_t addr;
+        mboot_addr_t remain;
+        if (stream->file_pos < stream->seg0_byte_len) {
+            // Reading from segment 0.
+            mboot_addr_t seg0_pos = stream->file_pos;
+            addr = stream->seg0_base_addr + seg0_pos;
+            remain = stream->seg0_byte_len - seg0_pos;
+        } else {
+            // Reading from segment 1.
+            mboot_addr_t seg1_pos = stream->file_pos - stream->seg0_byte_len;
+            addr = stream->seg1_base_addr + seg1_pos;
+            remain = stream->seg1_byte_len - seg1_pos;
+            if (!remain) {
+                // At the end of segment 1.
+                break;
+            }
+        }
+        size_t l = MIN(len, remain);
+        hw_read(addr, l, buf);
+        stream->file_pos += l;
+        buf += l;
+        len -= l;
+    }
+    return orig_len - len;
+}
+
+const stream_methods_t vfs_raw_stream_methods = {
+    vfs_raw_stream_open,
+    vfs_raw_stream_close,
+    vfs_raw_stream_read,
+};
+
+#endif // MBOOT_FSLOAD && MBOOT_VFS_RAW