[PATCH v4 0/5] Add fastboot to SPL

Some recovery and initial-provisioning flows need a standard host protocol
before usable firmware is available in persistent storage. U-Boot already
provides fastboot, but the implementation can currently be started only
from the U-Boot-proper command line.

This series makes USB fastboot available as an opt-in SPL service,
including MMC partition flashing and Android sparse images. The interface
is kept deliberately narrower in SPL: it does not support the boot command
or filesystem probing, and reboot support remains platform-dependent.

The first four patches separate the generic preparation from SPL
enablement. They factor out the USB session runner, route USB reboot
through the common handler, make shared fastboot configuration phase-aware,
and add phase-aware sparse-image support. The final patch then contains the
SPL-specific Kconfig, gadget behavior, and documentation.

No fastboot code or supporting library is added to SPL when SPL_FASTBOOT is
disabled, so the feature has no size cost for existing SPL builds.

---
Changes in v4:
- Drop RFC status.
- Make the USB fastboot helper and gadget build rules phase-aware.
- Use a separate command table for the SPL-supported command subset.
- Document the commands available in SPL.
- Apply the requested Makefile, annotation and preprocessor cleanups.
- Link to v3: https://patch.msgid.link/20260731-ccaione-upstream-spl-fastboot-v3-0-dbea3ff4529e@baylibre.com

Changes in v3:
- Rename the USB session helper to fastboot_usb_run().
- Initialize UDP and TCP sessions in their transport helpers.
- Remove a redundant USB session return assignment.
- Collect the Reviewed-by tag.
- Link to v2: https://patch.msgid.link/20260722-ccaione-upstream-spl-fastboot-v2-0-2ba3f71c42bc@baylibre.com

Changes in v2:
- Split the common USB session runner into a prerequisite patch.
- Route USB reboot through the common fastboot handler separately.
- Split phase-aware fastboot configuration and build rules.
- Split phase-aware Android sparse-image support.
- Keep SPL-specific behavior in the final patch.
- No functional change from v1.
- Link to v1: https://patch.msgid.link/20260719-ccaione-upstream-spl-fastboot-v1-1-c9bab5b0ba72@baylibre.com

---
Carlo Caione (5):
      fastboot: factor out the USB session runner
      fastboot: use the common handler for USB reboot
      fastboot: make shared configuration checks phase-aware
      image: sparse: add phase-aware SPL support
      fastboot: add SPL support

 cmd/fastboot.c                  | 53 +++-------------------
 doc/android/fastboot.rst        | 31 +++++++++++++
 drivers/Makefile                |  2 +-
 drivers/fastboot/Kconfig        | 92 +++++++++++++++++++++++++++++++++++++-
 drivers/fastboot/Makefile       |  9 ++--
 drivers/fastboot/fb_block.c     |  9 ++--
 drivers/fastboot/fb_command.c   | 97 ++++++++++++++++++++++++++++++++---------
 drivers/fastboot/fb_common.c    | 23 +++++++++-
 drivers/fastboot/fb_getvar.c    | 19 +++++---
 drivers/fastboot/fb_mmc.c       | 36 +++++++--------
 drivers/fastboot/fb_usb.c       | 66 ++++++++++++++++++++++++++++
 drivers/usb/gadget/Makefile     |  2 +-
 drivers/usb/gadget/f_fastboot.c |  6 ++-
 include/fastboot.h              | 10 +++++
 lib/Kconfig                     | 11 +++++
 lib/Makefile                    |  3 +-
 lib/image-sparse.c              |  2 +-
 17 files changed, 360 insertions(+), 111 deletions(-)
---
base-commit: 527115ef6783cec49e5610c523c124b399011361
change-id: 20260718-ccaione-upstream-spl-fastboot-14fa2b6b2b64

Best regards,
--  
Carlo Caione <[email protected]>