[PATCH v3 0/6] arm: snapdragon: Add snagboot support for Lemans-EVK

[Balaji Selvanathan]

This series adds support for running U-Boot in snagboot mode on
Qualcomm Snapdragon platforms, targeting the Lemans-EVK board.

Snagboot is an open-source, scriptable flashing framework that provides
an alternative to the proprietary Firehose protocol for device
provisioning. Like the traditional EDL+Firehose flow, Snagboot uses the
Qualcomm boot ROM recovery mode (EDL) and Sahara protocol to download
and execute bootloaders. However, instead of using the proprietary
Firehose programmer, Snagboot loads U-Boot into DDR and uses the
standard fastboot protocol for device flashing.

The framework consists of three modular components: snagrecover
(downloads XBL/QCLib to initialize DDR and load U-Boot into RAM),
snagflash (communicates with U-Boot over USB using fastboot to flash
system images), and snagfactory (orchestrates parallel factory
flashing tasks).

In the snagboot execution flow, ROM code in recovery mode loads
snagrecover, which downloads XBL to internal memory. XBL executes
and initializes DDR, then snagrecover downloads U-Boot into DDR and
transfers control to it. At this point, XBL has left the MMU enabled
with its own page tables and has not initialized PSCI firmware or
populated the Command DB. U-Boot must handle this non-standard boot
environment to enter fastboot mode for device flashing.

This series addresses the specific requirements of the snagboot flow:

Patch 1 changes SYSRESET_PSCI from 'select' to 'imply' so it can
be disabled on platforms where PSCI firmware is unavailable.

Patch 2 guards show_psci_version() and qcom_psci_fixup() with
CONFIG_ARM_SMCCC to prevent build failures when SMCCC is disabled.

Patch 3 adds CONFIG_QCOM_SNAGBOOT_SUPPORT option to enable snagboot
mode support on Qualcomm platforms.

Patch 4 disables the MMU and invalidates TLBs at the earliest entry
point to clear stale page tables left by previous bootloader
before U-Boot sets up its own MMU.

Patch 5 adds QCOM_COMMAND_DB_OPTIONAL to allow the CMD DB driver to
bind successfully when CMD DB data is not populated by XBL, logging
a warning instead of failing.

Patch 6 adds qcom_lemans_snagboot_defconfig for Lemans-EVK, based
on qcom_defconfig with snagboot-specific settings.

Signed-off-by: Balaji Selvanathan <balaji.selvanathan at oss.qualcomm.com>
---
Changes in v3:
- Brought the MMU disable logic under CONFIG_QCOM_SNAGBOOT_SUPPORT
  ifdef condition
- Moved the MMU disable codes to a new seperate file
- Used "if (IS_ENABLED(CONFIG_QCOM_COMMAND_DB_OPTIONAL))" instead
  of #ifdef
- Removed enabling QCOM_COMMAND_DB_OPTIONAL, ENABLE_ARM_SOC_BOOT0_HOOK
  and SKIP_RELOCATE as they are now automatically enabled by
  QCOM_SNAGBOOT_SUPPORT selection 
- Removed updating MAINTAINERS as the defconfig file is picked up by
  the "N: qcom" line
- Link to v2: https://lore.kernel.org/u-boot/20260608-snagboot-v2-0-036bb0343bf7@oss.qualcomm.com/

Changes in v2:
- Changed SYSRESET_PSCI from 'select' to 'imply'
- Guard show_psci_version() and qcom_psci_fixup() with CONFIG_ARM_SMCCC
- Disables the MMU and invalidates TLBs at the earliest entry point
- Add qcom_lemans_snagboot_defconfig for Lemans-EVK
- Link to v1: https://lore.kernel.org/u-boot/20260409-cmddb-v1-1-b10549b34133@oss.qualcomm.com/

---
Balaji Selvanathan (6):
      arm: snapdragon: Make SYSRESET_PSCI optional
      arm: snapdragon: Guard PSCI functions with CONFIG_ARM_SMCCC
      arm: snapdragon: Add CONFIG_QCOM_SNAGBOOT_SUPPORT option
      arm: snapdragon: Disable MMU early before U-Boot reset vector
      soc: qcom: cmd-db: Allow boot without CMD DB data
      configs: add qcom_lemans_snagboot_defconfig for Lemans-EVK

 arch/arm/Kconfig                                   |  2 +-
 arch/arm/mach-snapdragon/Kconfig                   | 13 ++++++
 arch/arm/mach-snapdragon/board.c                   |  6 +++
 arch/arm/mach-snapdragon/include/mach/boot0.h      |  2 +
 .../mach-snapdragon/include/mach/snagboot_boot0.h  | 53 ++++++++++++++++++++++
 configs/qcom_lemans_snagboot_defconfig             | 45 ++++++++++++++++++
 drivers/soc/qcom/Kconfig                           | 18 ++++++++
 drivers/soc/qcom/cmd-db.c                          | 14 +++++-
 8 files changed, 150 insertions(+), 3 deletions(-)
---
base-commit: e1c3db1f788ed8106840e81b795e030cbe0020b7
change-id: 20260616-sngboot-760714938d18

Best regards,
-- 
Balaji Selvanathan <balaji.selvanathan at oss.qualcomm.com>