Add a boot device driver for UBI (Unsorted Block Images) that enables
bootstd to scan UBI volumes for FIT images.
The driver:
- Has a hunt callback that auto-attaches UBI: walks the DT for the
first partition with compatible = "linux,ubi", finds the matching
MTD device, and calls ubi_part_from_mtd() to attach
- Binds directly via bootdev_bind() as a child of the top-level MTD
device, using a distinct name ("ubibootdev") to coexist with the
MTD bootdev
- Iterates UBI volumes using iter->part as an index
- Reads the first bytes of each volume and checks for a valid FDT
header via fdt_check_header()
- Stores the UBI volume name in bflow->bootmeth_priv for the
bootmeth's boot() to pass to image_loader_init_ubi()
- Returns -ESHUTDOWN when all volumes are exhausted
Like the MTD bootdev, calls bootmeth_check() first so that only
compatible bootmeths produce bootflows. Inert until bootmeth_openwrt
is extended to accept UBI bootdevs.
Signed-off-by: Daniel Golle <[email protected]>
---
boot/Kconfig | 9 +++
boot/Makefile | 1 +
boot/ubi_bootdev.c | 180 +++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 190 insertions(+)
create mode 100644 boot/ubi_bootdev.c
diff --git a/boot/Kconfig b/boot/Kconfig
index 63e373cc62d..75d40744e69 100644
--- a/boot/Kconfig
+++ b/boot/Kconfig
@@ -594,6 +594,15 @@ config BOOTDEV_MTD
This scans MTD partitions for uImage.FIT firmware images,
enabling raw-flash boot via the OpenWrt boot method.
+config BOOTDEV_UBI
+ bool "UBI bootdev support"
+ depends on CMD_UBI
+ depends on BOOTSTD
+ help
+ Enable a boot device for UBI (Unsorted Block Images).
+ This scans UBI volumes for uImage.FIT firmware images,
+ enabling raw-flash boot via the OpenWrt boot method.
+
config BOOTMETH_OPENWRT
bool "Bootdev support for OpenWrt"
depends on FIT
diff --git a/boot/Makefile b/boot/Makefile
index feeed4924dd..aa7968c3932 100644
--- a/boot/Makefile
+++ b/boot/Makefile
@@ -73,6 +73,7 @@ obj-$(CONFIG_$(PHASE_)BOOTMETH_VBE_SIMPLE_OS) +=
vbe_simple_os.o
obj-$(CONFIG_$(PHASE_)BOOTMETH_ANDROID) += bootmeth_android.o
obj-$(CONFIG_$(PHASE_)BOOTDEV_MTD) += mtd_bootdev.o
+obj-$(CONFIG_$(PHASE_)BOOTDEV_UBI) += ubi_bootdev.o
obj-$(CONFIG_$(PHASE_)BOOTMETH_OPENWRT) += bootmeth_openwrt.o
obj-$(CONFIG_IMAGE_LOADER) += image-loader.o
diff --git a/boot/ubi_bootdev.c b/boot/ubi_bootdev.c
new file mode 100644
index 00000000000..03131a4ee1b
--- /dev/null
+++ b/boot/ubi_bootdev.c
@@ -0,0 +1,180 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * UBI boot device
+ *
+ * Copyright (C) 2026 Daniel Golle <[email protected]>
+ */
+
+#define LOG_CATEGORY UCLASS_BOOTSTD
+
+#include <bootdev.h>
+#include <bootflow.h>
+#include <bootmeth.h>
+#include <dm.h>
+#include <dm/ofnode.h>
+#include <malloc.h>
+#include <mtd.h>
+#include <ubi_uboot.h>
+#include <linux/libfdt.h>
+
+static int ubi_bootdev_get_bootflow(struct udevice *dev,
+ struct bootflow_iter *iter,
+ struct bootflow *bflow)
+{
+ struct ubi_device *ubi;
+ struct ubi_volume *vol;
+ struct mtd_info *ubi_mtd, *top_mtd, *part;
+ char buf[40];
+ char dname[60];
+ int ubi_part_idx = 0;
+ int n = 0;
+ int i, ret;
+
+ ret = bootmeth_check(bflow->method, iter);
+ if (ret)
+ return log_msg_ret("chk", ret);
+
+ ubi = ubi_devices[0];
+ if (!ubi)
+ return log_msg_ret("ubi", -ENODEV);
+
+ /* Count volumes so the scanning framework knows the bound */
+ for (i = 0; i < ubi->vtbl_slots; i++) {
+ if (ubi->volumes[i])
+ n++;
+ }
+ if (n)
+ iter->max_part = n - 1;
+
+ n = 0;
+
+ /* Walk to the iter->part'th UBI volume */
+ for (i = 0; i < ubi->vtbl_slots; i++) {
+ vol = ubi->volumes[i];
+ if (!vol)
+ continue;
+ if (n == iter->part)
+ goto found;
+ n++;
+ }
+ return -ESHUTDOWN;
+
+found:
+ ret = ubi_volume_read(vol->name, buf, 0, sizeof(buf));
+ if (ret)
+ return log_msg_ret("rd", -EIO);
+
+ if (fdt_check_header(buf))
+ return log_msg_ret("fdt", -ENOENT);
+
+ /*
+ * Find the MTD partition index hosting UBI so we can display
+ * a meaningful partition number in the bootflow listing.
+ */
+ ubi_mtd = ubi->mtd;
+ top_mtd = ubi_mtd;
+ while (top_mtd->parent)
+ top_mtd = top_mtd->parent;
+
+ n = 0;
+ list_for_each_entry(part, &top_mtd->partitions, node) {
+ if (part == ubi_mtd) {
+ ubi_part_idx = n;
+ break;
+ }
+ n++;
+ }
+
+ /* Device-style name and partition index for bootflow list display */
+ snprintf(dname, sizeof(dname), "%s.part_%x", dev->name, ubi_part_idx);
+ bflow->name = strdup(dname);
+ bflow->part = ubi_part_idx;
+ bflow->fname = strdup(vol->name);
+ bflow->bootmeth_priv = strdup(vol->name);
+ bflow->state = BOOTFLOWST_MEDIA;
+
+ return bootmeth_read_bootflow(bflow->method, bflow);
+}
+
+static int ubi_bootdev_bind(struct udevice *dev)
+{
+ struct bootdev_uc_plat *ucp = dev_get_uclass_plat(dev);
+
+ ucp->prio = BOOTDEVP_4_SCAN_FAST;
+
+ return 0;
+}
+
+/**
+ * ubi_bootdev_hunt() - attach UBI and bind a bootdev for it
+ *
+ * Walk the DT for the first partition with compatible = "linux,ubi",
+ * find its MTD device, attach UBI via ubi_part_from_mtd(), then bind
+ * a ubi_bootdev as a child of the top-level MTD DM device.
+ */
+static int ubi_bootdev_hunt(struct bootdev_hunter *info, bool show)
+{
+ struct udevice *bdev;
+ struct mtd_info *mtd;
+ ofnode node;
+ int ret;
+
+ mtd_probe_devices();
+
+ if (!ubi_devices[0]) {
+ ofnode_for_each_compatible_node(node, "linux,ubi") {
+ mtd_for_each_device(mtd) {
+ if (ofnode_equal(mtd->flash_node, node))
+ goto found;
+ }
+ }
+ return -ENOENT;
+found:
+ ret = ubi_part_from_mtd(mtd);
+ if (ret)
+ return log_msg_ret("att", -ENOENT);
+ }
+
+ /* Find the top-level MTD device for the attached UBI */
+ mtd = ubi_devices[0]->mtd;
+ while (mtd->parent)
+ mtd = mtd->parent;
+
+ if (!mtd->dev)
+ return log_msg_ret("dev", -ENODEV);
+
+ /*
+ * Bind directly — bootdev_setup_for_dev() cannot be used here
+ * because the MTD bootdev may already occupy the single bootdev
+ * child slot.
+ */
+ ret = bootdev_bind(mtd->dev, "ubi_bootdev", "ubibootdev", &bdev);
+ if (ret)
+ return log_msg_ret("bd", ret);
+
+ return 0;
+}
+
+struct bootdev_ops ubi_bootdev_ops = {
+ .get_bootflow = ubi_bootdev_get_bootflow,
+};
+
+static const struct udevice_id ubi_bootdev_ids[] = {
+ { .compatible = "u-boot,bootdev-ubi" },
+ { }
+};
+
+U_BOOT_DRIVER(ubi_bootdev) = {
+ .name = "ubi_bootdev",
+ .id = UCLASS_BOOTDEV,
+ .ops = &ubi_bootdev_ops,
+ .bind = ubi_bootdev_bind,
+ .of_match = ubi_bootdev_ids,
+};
+
+BOOTDEV_HUNTER(ubi_bootdev_hunter) = {
+ .prio = BOOTDEVP_4_SCAN_FAST,
+ .uclass = UCLASS_MTD,
+ .drv = DM_DRIVER_REF(ubi_bootdev),
+ .hunt = ubi_bootdev_hunt,
+};
--
2.53.0
