[PATCH v6 0/8] arm: snapdragon: Add snagboot support for Lemans-EVK

[Balaji Selvanathan via U-Boot <u-boot@lists.u-boot-project.org>]

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 EDL mode 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 EDL 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.

Support for Qualcomm Lemans-EVK SOC in Snagboot is now available in
https://github.com/qualcomm-linux/snagboot/tree/qcom-next
Soon these Snagboot changes will be upstreamed to https://github.com/bootlin/snagboot

When U-Boot executes in Snagboot flow, it has to deal with missing
platform services such as TrustZone (TZ), Hypervisor and AOP (which 
populates CMD DB data).

This series depends on the following patch/series, which are already
picked up in qcom-next
https://lore.kernel.org/all/20260508-qcom_spl-v7-4-7d0e22aaaa8f@seznam.cz/
https://lore.kernel.org/u-boot/20260618-b4-modernise-smem-v3-0-472391477988@linaro.org/

Signed-off-by: Balaji Selvanathan <balaji.selvanathan@oss.qualcomm.com>
---
Changes in v6:
- Forget to send summary in v5 cover letter, no other changes
  in v6
- Link to v5: https://marc.info/?l=u-boot&m=178577208345353&w=2

Changes in v5:
- Make QCOM_BOOT0_SNAGBOOT_MODE as hidden config dependent on 
  QCOM_SNAGBOOT_MODE
- Disable C (Dcache) bit of SCTLR_EL3 register during MMU disable
- Remove now unused QCOM_COMMAND_DB_OPTIONAL Kconfig definition
- Disable unnecessar I2C configs (for Snagboot) in Qcom Snagboot
  config fragment
- Add build steps for compiling U-Boot for Snagboot mode in
  Qcom Snagboot doc
- Link to v4: https://lore.kernel.org/u-boot/20260619-snagboot-v4-0-385497442db2@oss.qualcomm.com/

Changes in v4:
- Renamed QCOM_SNAGBOOT_SUPPORT to QCOM_SNAGBOOT_MODE
- Make SYSRESET_PSCI dependent on QCOM_SNAGBOOT_MODE
- Place Snagboot related configs in seperate config fragment
  called configs/qcom-snagboot.config
- Include above config fragment in
  configs/qcom_lemans_snagboot_defconfig
- Removed Lemans EVK override dtsi: arch/arm/dts/lemans-evk-u-boot.dtsi
- Removed QCOM_COMMAND_DB_OPTIONAL as now we use
  CONFIG_QCOM_SNAGBOOT_MODE
- Added documentation on U-Boot for Snagboot 
- Link to v3: https://lore.kernel.org/u-boot/20260616-sngboot-v3-0-6fb0dee8125c@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 (8):
      arm: snapdragon: Make SYSRESET_PSCI optional
      arm: snapdragon: Guard PSCI functions with CONFIG_ARM_SMCCC
      arm: snapdragon: Disable MMU early before U-Boot reset vector
      arm: snapdragon: Add CONFIG_QCOM_SNAGBOOT_MODE option
      soc: qcom: cmd-db: Allow boot without CMD DB data
      arch: arm: dts: remove Lemans EVK override DTS
      configs: add qcom_lemans_snagboot_defconfig for Lemans-EVK
      doc: qualcomm: Add snagboot mode documentation

 arch/arm/Kconfig                                   |   2 +-
 arch/arm/dts/lemans-evk-u-boot.dtsi                |  19 --
 arch/arm/mach-snapdragon/Kconfig                   |  20 ++
 arch/arm/mach-snapdragon/board.c                   |   6 +
 arch/arm/mach-snapdragon/include/mach/boot0.h      |   2 +
 .../mach-snapdragon/include/mach/snagboot_boot0.h  |  27 +++
 configs/qcom-snagboot.config                       |  46 +++++
 configs/qcom_lemans_snagboot_defconfig             |  18 ++
 doc/board/qualcomm/index.rst                       |   1 +
 doc/board/qualcomm/snagboot.rst                    | 224 +++++++++++++++++++++
 drivers/soc/qcom/cmd-db.c                          |  15 +-
 11 files changed, 358 insertions(+), 22 deletions(-)
---
base-commit: f79edc9ad08ec0c3e40323ff17cc7166ad2b9e71
change-id: 20260731-snagboot-4e9f66f0252d

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