[PATCH v2 0/5] board: samsung: e850-96: Support USB boot

[Sam Protsenko]

When U-Boot is executed during USB boot [1,2] on E850-96 board, two
issues happen:

  1. eMMC fails to initialize
  2. Attempt to use USB PHY driver leads to abort

It was identified that issue #1 happens due to enalbed Flash Memory
Protector bits in MMC block registers during USB boot, and it's handled
in patch series [3].

Issue #2 on the other hand happens because ROM code expects the
bootloader (U-Boot) to download remaining binaries (LDFW and TZSW) over
USB using SMC calls. Before that, the access to USB blocks (USB PHY and
DWC3) is disabled, probably because corresponding TrustZone domains are
configured for access from Secure World only.

This patch series implements downloading LDFW and TZSW firmware over USB
during USB boot, which makes it possible to use U-Boot for flashing
images to eMMC using fastboot and DFU protocols. That in turn simplifies
the U-Boot development, as one can use `dltool' [1] to run U-Boot binary
during USB boot, and update U-Boot on eMMC this way (e.g. using DFU).
It's not possible when using LittleKernel bootloader, as it expects
non-standard Samsung GPT partition, but in case of U-Boot we use the
regular one.

Once this patch series and patch series [3] are applied it'll be
possible to use U-Boot during USB boot. The two series are independent
of each other, and can be applied in any particular order.

Changes in v2:
  - [PATCH 4/5]: Return 0 on success in load_image_usb()

[1] https://gitlab.com/LinaroLtd/e850-96/tools/dltool
[2] https://docs.u-boot.org/en/latest/board/samsung/e850-96.html
[3] https://lore.kernel.org/u-boot/20251026010658.19271-1-semen.protsenko@linaro.org/

Sam Protsenko (5):
  board: samsung: e850-96: Keep public functions together
  board: samsung: e850-96: Add routines for checking boot dev
  board: samsung: e850-96: Split LDFW loading and init
  board: samsung: e850-96: Add routine for loading images over USB
  board: samsung: e850-96: Load firmwares over USB on USB boot

 board/samsung/e850-96/Makefile  |  2 +-
 board/samsung/e850-96/bootdev.c | 99 +++++++++++++++++++++++++++++++++
 board/samsung/e850-96/bootdev.h | 23 ++++++++
 board/samsung/e850-96/e850-96.c | 65 +++++++++++++++++-----
 board/samsung/e850-96/fw.c      | 76 ++++++++++++++++++-------
 board/samsung/e850-96/fw.h      | 10 +++-
 6 files changed, 240 insertions(+), 35 deletions(-)
 create mode 100644 board/samsung/e850-96/bootdev.c
 create mode 100644 board/samsung/e850-96/bootdev.h


base-commit: fd976ff3a233ae7c6a9f5bec790b02bbbf57bb24
-- 
2.39.5