Hi Daniel,
On Mon, 16 Feb 2026 at 14:24, Daniel Golle <[email protected]> wrote:
>
> 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;
This can just be done once, when !iter->part, since it cannot change.
> +
> + 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:
The above code need tightening up a bit!
> + 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;
Eek no we need to find the device, not the node. There must surely be
a link between the UBI and MTD in the data structures somewhere.
> +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
Regards,
Simon
