[PATCH v2] spl: Add generic SPL MTD loader support

[Santhosh Kumar K]

Hello Fabio,

On 20/02/26 08:42, Fabio Estevam wrote:
> From: Fabio Estevam <festevam at nabladev.com>
> 
> Add support for loading the next stage from an MTD device in SPL.
> 
> Introduce CONFIG_SPL_MTD_LOAD and a generic SPL MTD loader
> implementation that uses the MTD subsystem to read the U-Boot payload.
> 
> The loader works with any MTD-backed storage, including raw NAND and
> SPI NAND, without being tied to a specific NAND type.
> 
> The payload offset defaults to CONFIG_SYS_MTD_U_BOOT_OFFS and can be
> overridden via the device tree property:
> 
>      u-boot,spl-payload-offset
> 
> To support both raw NAND and SPI NAND boot flows, the loader is
> registered for BOOT_DEVICE_NAND and BOOT_DEVICE_SPI. This allows it
> to operate correctly on platforms where the ROM reports either NAND
> or SPI as the boot source while using the same MTD-based loading
> infrastructure.
> 
> The required NAND core and SPI NAND drivers are built for SPL when
> CONFIG_SPL_MTD_LOAD is enabled.
> 
> This provides reusable infrastructure for boards that boot from MTD
> devices without relying on SPI-specific or NAND-specific SPL loaders.
> 
> Signed-off-by: Fabio Estevam <festevam at nabladev.com>
> ---
> Changes since v1:
> - Use uclass_get_device_by_seq().
> - Use puts() instead of debug() for error.
> - Include the new loader to include/spl_load.h.
> - Introduce SPL_MTD_SPI_NAND.
> 
>   common/spl/Kconfig        | 30 ++++++++++++++
>   common/spl/Makefile       |  1 +
>   common/spl/spl_mtd.c      | 83 +++++++++++++++++++++++++++++++++++++++
>   drivers/mtd/Makefile      |  1 +
>   drivers/mtd/nand/Makefile |  4 +-
>   include/spl_load.h        |  1 +
>   6 files changed, 119 insertions(+), 1 deletion(-)
>   create mode 100644 common/spl/spl_mtd.c
> 
> diff --git a/common/spl/Kconfig b/common/spl/Kconfig
> index 2998b7acb75f..16dbc5b54324 100644
> --- a/common/spl/Kconfig
> +++ b/common/spl/Kconfig
> @@ -933,6 +933,12 @@ config SYS_MMCSD_FS_BOOT_PARTITION
>   	  used in fs mode.
>   	  Use -1 as a special value to use the first bootable partition.
>   
> +config SYS_SPL_MTD_SEQ
> +	int "MTD device number for the SPL load"
> +	default 0
> +	help
> +	  MTD device number used for the SPL load.
> +
>   config SPL_MMC_TINY
>   	bool "Tiny MMC framework in SPL"
>   	depends on SPL_MMC
> @@ -1578,6 +1584,30 @@ config SPL_SPI_LOAD
>   
>   endif # SPL_SPI_FLASH_SUPPORT
>   
> +config SPL_MTD_LOAD
> +	bool "Support loading from a generic MTD device"
> +	depends on SPL
> +	depends on MTD && DM_MTD
> +	help
> +	  Enable support for loading the next stage from an MTD device
> +	  using the MTD subsystem in SPL.
> +
> +	  This supports raw NAND and SPI NAND devices.
> +
> +config SPL_MTD_SPI_NAND
> +	bool "Enable SPI NAND support in SPL"
> +	depends on SPL_MTD_LOAD
> +	select MTD_SPI_NAND
> +	help
> +	 Build SPI NAND support for SPL.
> +
> +config SYS_MTD_U_BOOT_OFFS
> +	hex "address of U-boot payload in the MTD device"
> +	default 0x0
> +	help
> +	 Address within the MTD device where the U-boot payload is fetched
> +	 from.
> +
>   config SYS_SPI_U_BOOT_OFFS
>   	hex "address of u-boot payload in SPI flash"
>   	default 0x8000 if ARCH_SUNXI
> diff --git a/common/spl/Makefile b/common/spl/Makefile
> index 4c9482bd3096..67fc1cd1b396 100644
> --- a/common/spl/Makefile
> +++ b/common/spl/Makefile
> @@ -35,6 +35,7 @@ obj-$(CONFIG_$(PHASE_)NVME) += spl_nvme.o
>   obj-$(CONFIG_$(PHASE_)SEMIHOSTING) += spl_semihosting.o
>   obj-$(CONFIG_$(PHASE_)DFU) += spl_dfu.o
>   obj-$(CONFIG_$(PHASE_)SPI_LOAD) += spl_spi.o
> +obj-$(CONFIG_SPL_MTD_LOAD) += spl_mtd.o
>   obj-$(CONFIG_$(PHASE_)RAM_SUPPORT) += spl_ram.o
>   obj-$(CONFIG_$(PHASE_)USB_SDP_SUPPORT) += spl_sdp.o
>   endif
> diff --git a/common/spl/spl_mtd.c b/common/spl/spl_mtd.c
> new file mode 100644
> index 000000000000..904f1fbad834
> --- /dev/null
> +++ b/common/spl/spl_mtd.c
> @@ -0,0 +1,83 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +
> +/*
> + * Generic SPL loader for MTD devices.
> + *
> + * Based on spl_spi.c, which is:
> + *
> + * Copyright (C) 2011 OMICRON electronics GmbH
> + *
> + * based on drivers/mtd/nand/raw/nand_spl_load.c
> + *
> + * Copyright (C) 2011
> + * Heiko Schocher, DENX Software Engineering, hs at denx.de.
> + */
> +
> +#include <config.h>
> +#include <errno.h>
> +#include <image.h>
> +#include <log.h>
> +#include <spl.h>
> +#include <spl_load.h>
> +
> +#include <dm.h>
> +#include <dm/ofnode.h>
> +#include <dm/uclass.h>
> +#include <mtd.h>
> +
> +static struct mtd_info *spl_mtd_get_device(void)
> +{
> +	struct udevice *dev;
> +	int ret;
> +
> +	ret = uclass_get_device_by_seq(UCLASS_MTD, CONFIG_SYS_SPL_MTD_SEQ, &dev);
> +	if (ret)
> +		return NULL;
> +
> +	return dev_get_uclass_priv(dev);
> +}
> +
> +static ulong spl_mtd_read(struct spl_load_info *load,
> +			  ulong offs, ulong size, void *buf)
> +{
> +	struct mtd_info *mtd = load->priv;
> +	size_t retlen;
> +	int ret;
> +
> +	ret = mtd_read(mtd, offs, size, &retlen, buf);
> +	if (ret && !mtd_is_bitflip(ret))
> +		return 0;
> +
> +	if (retlen != size)
> +		return 0;
> +
> +	return retlen;
> +}
> +
> +static int spl_mtd_load_image(struct spl_image_info *spl_image,
> +			      struct spl_boot_device *bootdev)
> +{
> +	struct spl_load_info load;
> +	struct mtd_info *mtd;
> +	ulong offset;
> +
> +	mtd = spl_mtd_get_device();
> +	if (!mtd) {
> +		puts("SPL: No MTD device found\n");
> +		return -ENODEV;
> +	}
> +
> +	spl_load_init(&load, spl_mtd_read, mtd, mtd->writesize);
> +
> +	offset = CONFIG_SYS_MTD_U_BOOT_OFFS;
> +
> +	if (CONFIG_IS_ENABLED(OF_REAL))
> +		offset = ofnode_conf_read_int("u-boot,spl-payload-offset",
> +					      offset);
> +
> +	return spl_load(spl_image, bootdev, &load, 0, offset);
> +}

I believe bad block management is critical during image loading, as
this directly impacts the device boot flow. But, I do not see any check
for bad blocks or logic to skip them in the load_image implementation.

Regards,
Santhosh.

> +