[PATCH 1/2] fastboot: Add UFS flash backend
Mattijs Korpershoek
mkorpershoek at kernel.org
Mon Mar 23 11:00:50 CET 2026
On Wed, Mar 04, 2026 at 17:23, Neil Armstrong <neil.armstrong at linaro.org> wrote:
> Hi,
>
> On 3/3/26 07:29, Ruitong Su wrote:
>> Add a fastboot backend for UFS (Universal Flash Storage) devices.
>> UFS devices are accessed through the SCSI subsystem, with each UFS
>> LUN exposed as a separate SCSI block device.
>>
>> The key feature is multi-LUN partition addressing using the syntax
>> "<scsi_dev>#<partition_name>" (e.g. "0#system", "1#boot_a").
>> Unqualified names fall back to the default SCSI device configured
>> via CONFIG_FASTBOOT_FLASH_UFS_DEV.
>
> I get this is a cool feature, but multi-LUN is exactly like multi-block,
> so could you try to extend the block to support multiple different block
> devices instead ? no need to limit this to UFS...
I agree with Neil here. Can you explain why this needs to be UFS
specific or re-spin a new version to extend block support?
>
> Thanks,
> Neil
>
>>
>> The implementation reuses the existing fb_block helpers for raw
>> image, sparse image, and erase operations, adding only the
>> UFS-specific partition lookup and GPT handling logic on top.
>>
>> Partition lookup uses a quiet iteration via part_get_info() instead
>> of the verbose part_get_info_by_name() / part_get_info_by_dev_and_
>> name_or_num(), which avoids noisy console output during fastboot
>> getvar probing (has-slot, partition-size queries).
>>
>> Signed-off-by: Ruitong Su <suruitong at lixiang.com>
>> ---
>> MAINTAINERS | 1 +
>> drivers/fastboot/Kconfig | 30 ++++++-
>> drivers/fastboot/Makefile | 1 +
>> drivers/fastboot/fb_ufs.c | 164 ++++++++++++++++++++++++++++++++++++++
>> include/fb_ufs.h | 49 ++++++++++++
>> 5 files changed, 243 insertions(+), 2 deletions(-)
>> create mode 100644 drivers/fastboot/fb_ufs.c
>> create mode 100644 include/fb_ufs.h
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index f8d4f6ee8b2..071102f47fd 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -1197,6 +1197,7 @@ F: cmd/fastboot.c
>> F: doc/android/fastboot*.rst
>> F: include/fastboot.h
>> F: include/fastboot-internal.h
>> +F: include/fb_ufs.h
>> F: include/net/fastboot_tcp.h
>> F: include/net/fastboot_udp.h
>> F: drivers/fastboot/
>> diff --git a/drivers/fastboot/Kconfig b/drivers/fastboot/Kconfig
>> index 576c3ef8a45..8569bec5d9b 100644
>> --- a/drivers/fastboot/Kconfig
>> +++ b/drivers/fastboot/Kconfig
>> @@ -92,7 +92,7 @@ config FASTBOOT_FLASH
>> bool "Enable FASTBOOT FLASH command"
>> default y if ARCH_SUNXI && ( MMC || MTD_RAW_NAND )
>> default y if ARCH_ROCKCHIP && MMC
>> - depends on MMC || (MTD_RAW_NAND && CMD_MTDPARTS) || DM_SPI_FLASH || BLK
>> + depends on MMC || (MTD_RAW_NAND && CMD_MTDPARTS) || DM_SPI_FLASH || BLK || (UFS && SCSI)
>> select IMAGE_SPARSE
>> help
>> The fastboot protocol includes a "flash" command for writing
>> @@ -124,12 +124,38 @@ config FASTBOOT_FLASH_SPI
>> bool "FASTBOOT on SPI flash"
>> depends on DM_SPI_FLASH
>>
>> +config FASTBOOT_FLASH_UFS
>> + bool "FASTBOOT on UFS"
>> + depends on UFS && SCSI
>> + help
>> + This enables support for the fastboot "flash" and "erase"
>> + commands on UFS (Universal Flash Storage) devices. UFS
>> + devices are accessed through the SCSI subsystem, with each
>> + UFS LUN exposed as a separate SCSI block device.
>> +
>> + Partitions are addressed using the syntax
>> + "<scsi_dev>#<partition_name>" (e.g. "0#system") to
>> + disambiguate across multiple UFS LUNs. Unqualified names
>> + fall back to the default SCSI device number.
>> +
>> config FASTBOOT_FLASH_BLOCK
>> bool "FASTBOOT on block device"
>> depends on BLK
>>
>> endchoice
>>
>> +config FASTBOOT_FLASH_UFS_DEV
>> + int "Define FASTBOOT UFS default SCSI device number"
>> + depends on FASTBOOT_FLASH_UFS
>> + default 0
>> + help
>> + The default SCSI device number for UFS fastboot operations.
>> + UFS LUNs are exposed as SCSI block devices by the UFS driver.
>> + Use "scsi scan" followed by "scsi info" to discover the
>> + mapping between SCSI device numbers and UFS LUNs. Typically
>> + device 0 corresponds to UFS LUN 0. When the partition name
>> + does not contain a "#" separator, this device is used.
>> +
>> config FASTBOOT_FLASH_MMC_DEV
>> int "Define FASTBOOT MMC FLASH default device"
>> depends on FASTBOOT_FLASH_MMC
>> @@ -227,7 +253,7 @@ config FASTBOOT_FLASH_BLOCK_DEVICE_ID
>>
>> config FASTBOOT_GPT_NAME
>> string "Target name for updating GPT"
>> - depends on FASTBOOT_FLASH_MMC && EFI_PARTITION
>> + depends on (FASTBOOT_FLASH_MMC || FASTBOOT_FLASH_UFS) && EFI_PARTITION
>> default "gpt"
>> help
>> The fastboot "flash" command supports writing the downloaded
>> diff --git a/drivers/fastboot/Makefile b/drivers/fastboot/Makefile
>> index a341af076d1..93a5227b737 100644
>> --- a/drivers/fastboot/Makefile
>> +++ b/drivers/fastboot/Makefile
>> @@ -7,4 +7,5 @@ obj-$(CONFIG_FASTBOOT_FLASH_BLOCK) += fb_block.o
>> # MMC reuses block implementation
>> obj-$(CONFIG_FASTBOOT_FLASH_MMC) += fb_block.o fb_mmc.o
>> obj-$(CONFIG_FASTBOOT_FLASH_NAND) += fb_nand.o
>> +obj-$(CONFIG_FASTBOOT_FLASH_UFS) += fb_block.o fb_ufs.o
>> obj-$(CONFIG_FASTBOOT_FLASH_SPI) += fb_spi_flash.o
>> diff --git a/drivers/fastboot/fb_ufs.c b/drivers/fastboot/fb_ufs.c
>> new file mode 100644
>> index 00000000000..1273c946491
>> --- /dev/null
>> +++ b/drivers/fastboot/fb_ufs.c
>> @@ -0,0 +1,164 @@
>> +// SPDX-License-Identifier: GPL-2.0+
>> +/*
>> + * Copyright (C) 2026 Li Auto Inc.
>> + *
>> + * UFS (Universal Flash Storage) backend for fastboot.
>> + *
>> + * UFS devices in U-Boot are accessed through the SCSI subsystem, with
>> + * each UFS LUN exposed as a separate SCSI block device. This backend
>> + * provides UFS-aware partition lookup with multi-LUN addressing, layered
>> + * on top of the generic fb_block helpers for the actual I/O.
>> + *
>> + * Partition addressing uses the syntax "<scsi_dev>#<partition_name>"
>> + * (e.g. "0#system") to disambiguate across multiple UFS LUNs.
>> + * Unqualified names fall back to CONFIG_FASTBOOT_FLASH_UFS_DEV.
>> + */
>> +
>> +#include <blk.h>
>> +#include <fastboot.h>
>> +#include <fastboot-internal.h>
>> +#include <fb_block.h>
>> +#include <fb_ufs.h>
>> +#include <image-sparse.h>
>> +#include <part.h>
>> +#include <vsprintf.h>
>> +#include <linux/printk.h>
>> +
>> +static struct blk_desc *fastboot_ufs_get_dev(char *response, int dev_num)
>> +{
>> + struct blk_desc *dev_desc;
>> +
>> + dev_desc = blk_get_dev("scsi", dev_num);
>> + if (!dev_desc || dev_desc->type == DEV_TYPE_UNKNOWN) {
>> + pr_err("invalid UFS/SCSI device %d\n", dev_num);
>> + fastboot_fail("invalid UFS device", response);
>> + return NULL;
>> + }
>> +
>> + return dev_desc;
>> +}
>> +
>> +static int fb_ufs_find_part(struct blk_desc *dev_desc, const char *name,
>> + struct disk_partition *info)
>> +{
>> + int i;
>> + int ret;
>> +
>> + for (i = 1; ; i++) {
>> + ret = part_get_info(dev_desc, i, info);
>> + if (ret)
>> + return ret;
>> + if (!strcmp(name, (char *)info->name))
>> + return i;
>> + }
>> +}
>> +
>> +int fastboot_ufs_get_part_info(const char *part_name,
>> + struct blk_desc **dev_desc,
>> + struct disk_partition *part_info,
>> + char *response)
>> +{
>> + int dev_num = CONFIG_FASTBOOT_FLASH_UFS_DEV;
>> + char name_buf[32];
>> + const char *name = part_name;
>> + int ret;
>> +
>> + if (!part_name || !*part_name) {
>> + fastboot_fail("partition not given", response);
>> + return -ENOENT;
>> + }
>> +
>> + /* Parse "<dev>#<name>" syntax for multi-LUN addressing */
>> + if (strchr(part_name, '#')) {
>> + if (sscanf(part_name, "%d#%31s", &dev_num, name_buf) != 2) {
>> + fastboot_fail("invalid partition spec", response);
>> + return -EINVAL;
>> + }
>> + name = name_buf;
>> + }
>> +
>> + *dev_desc = blk_get_dev("scsi", dev_num);
>> + if (!*dev_desc || (*dev_desc)->type == DEV_TYPE_UNKNOWN) {
>> + fastboot_fail("no such device", response);
>> + return -ENODEV;
>> + }
>> +
>> + ret = fb_ufs_find_part(*dev_desc, name, part_info);
>> + if (ret < 0) {
>> + fastboot_fail("no such partition", response);
>> + return -ENOENT;
>> + }
>> +
>> + return ret;
>> +}
>> +
>> +void fastboot_ufs_flash_write(const char *cmd, void *download_buffer,
>> + u32 download_bytes, char *response)
>> +{
>> + struct blk_desc *dev_desc;
>> + struct disk_partition info = {0};
>> +
>> +#if CONFIG_IS_ENABLED(EFI_PARTITION)
>> + {
>> + int dev_num = CONFIG_FASTBOOT_FLASH_UFS_DEV;
>> + char op_buf[16];
>> + const char *op = cmd;
>> +
>> + if (strchr(cmd, '#')) {
>> + if (sscanf(cmd, "%d#%15s", &dev_num, op_buf) == 2)
>> + op = op_buf;
>> + }
>> +
>> + if (!strcmp(op, CONFIG_FASTBOOT_GPT_NAME)) {
>> + dev_desc = fastboot_ufs_get_dev(response, dev_num);
>> + if (!dev_desc)
>> + return;
>> +
>> + printf("%s: updating GPT on scsi %d\n",
>> + __func__, dev_num);
>> + if (is_valid_gpt_buf(dev_desc, download_buffer)) {
>> + printf("%s: invalid GPT - refusing to write\n",
>> + __func__);
>> + fastboot_fail("invalid GPT partition",
>> + response);
>> + return;
>> + }
>> + if (write_mbr_and_gpt_partitions(dev_desc,
>> + download_buffer)) {
>> + printf("%s: writing GPT partitions failed\n",
>> + __func__);
>> + fastboot_fail("writing GPT partitions failed",
>> + response);
>> + return;
>> + }
>> + part_init(dev_desc);
>> + printf("........ success\n");
>> + fastboot_okay(NULL, response);
>> + return;
>> + }
>> + }
>> +#endif
>> +
>> + if (fastboot_ufs_get_part_info(cmd, &dev_desc, &info, response) < 0)
>> + return;
>> +
>> + if (is_sparse_image(download_buffer)) {
>> + fastboot_block_write_sparse_image(dev_desc, &info, cmd,
>> + download_buffer, response);
>> + } else {
>> + fastboot_block_write_raw_image(dev_desc, &info, cmd,
>> + download_buffer,
>> + download_bytes, response);
>> + }
>> +}
>> +
>> +void fastboot_ufs_erase(const char *cmd, char *response)
>> +{
>> + struct blk_desc *dev_desc;
>> + struct disk_partition info;
>> +
>> + if (fastboot_ufs_get_part_info(cmd, &dev_desc, &info, response) < 0)
>> + return;
>> +
>> + fastboot_block_raw_erase(dev_desc, &info, cmd, 0, response);
>> +}
>> diff --git a/include/fb_ufs.h b/include/fb_ufs.h
>> new file mode 100644
>> index 00000000000..d64d5aca81a
>> --- /dev/null
>> +++ b/include/fb_ufs.h
>> @@ -0,0 +1,49 @@
>> +/* SPDX-License-Identifier: GPL-2.0+ */
>> +/*
>> + * Copyright (C) 2026 Li Auto Inc.
>> + */
>> +
>> +#ifndef _FB_UFS_H_
>> +#define _FB_UFS_H_
>> +
>> +struct blk_desc;
>> +struct disk_partition;
>> +
>> +/**
>> + * fastboot_ufs_get_part_info() - Look up partition on UFS device
>> + *
>> + * Supports two naming conventions:
>> + * "<scsi_dev>#<partition_name>" -- explicit LUN targeting (e.g. "0#system")
>> + * "<partition_name>" -- searches on default UFS SCSI device
>> + *
>> + * @part_name: Partition specifier (see above)
>> + * @dev_desc: Pointer to returned block device descriptor
>> + * @part_info: Pointer to returned partition info
>> + * @response: Pointer to fastboot response buffer
>> + * Return: Partition number on success, negative on error
>> + */
>> +int fastboot_ufs_get_part_info(const char *part_name,
>> + struct blk_desc **dev_desc,
>> + struct disk_partition *part_info,
>> + char *response);
>> +
>> +/**
>> + * fastboot_ufs_flash_write() - Write downloaded image to UFS partition
>> + *
>> + * @cmd: Partition specifier ("0#system", "0#gpt", etc.)
>> + * @download_buffer: Pointer to downloaded image data
>> + * @download_bytes: Size of downloaded image
>> + * @response: Pointer to fastboot response buffer
>> + */
>> +void fastboot_ufs_flash_write(const char *cmd, void *download_buffer,
>> + u32 download_bytes, char *response);
>> +
>> +/**
>> + * fastboot_ufs_erase() - Erase a UFS partition
>> + *
>> + * @cmd: Partition specifier ("0#userdata", etc.)
>> + * @response: Pointer to fastboot response buffer
>> + */
>> +void fastboot_ufs_erase(const char *cmd, char *response);
>> +
>> +#endif /* _FB_UFS_H_ */
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