tree 3b123655ce0dda88ddad220b2de2fdb1a9e8ddcb
parent 701c207f90da087d02c530440eada1f91ccaa3b7
author Caleb Connolly <caleb.connolly@linaro.org> 1699976164 +0000
committer Caleb Connolly <caleb.connolly@linaro.org> 1701783324 +0000
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Qualcomm generic board support

Historically, Qualcomm boards in U-Boot have all had their own
board/qualcomm/xyz directory, their own CONFIG_TARGET_XYZ option, their
own hardcoded sysmap-xyz.c file, and their own U-Boot specific
devicetree with little/no compatibility with upstream DT.

This series makes a few final prepatory changes, and then replaces
almost all of the board specific code with generic alternatives. The end
result is that all Qualcomm boards both current and future (with the
exception of the db410c and db820c) can be supported by a single U-Boot
binary by just providing the correct DT. New boards can be added without
introducing any addition mach/ or board/ code or config options.

Due to the nature of this change, the patch ("mach-snapdragon:
generalise board support") has become pretty big, I tried a few
different ways to represent this in git history, but the other methods
(e.g. adding a stub "generic" target and removing it again) were more
confusing and made for much messier git history. The current patch is
mostly atomic, but requires regenerating the config.

The QCS404 EVB board had some code to enable the USB VBUS regulator,
this is dropped in favour of a adding a new vbus-supply property to the
dwc3-generic driver. This will also be used by the dragonboard845c in a
future patch. This handles the common case of a board requiring some
regulator be enabled for USB host mode.

A more detailed description of the changes is below.

== Memory map ==

The memory map was historically hardcoded into U-Boot, this meant that
U-Boot had to be built for a specific variant of a device. This is
changed to instead read the memory map from the DT /memory node.

Additionally, most boards mapped addresss 0x0 as valid, as a result if a
null pointer access happens then it will cause a bus stall (and board
hang). This is fixed so that null pointer accesses will now correctly
throw an exception.

== DT loading ==

Previously, boards used the FDT blob embedded into U-Boot (via
OF_SEPARATE). However, most Qualcomm boards run U-Boot as a secondary
bootloader, so we can instead rely on the first-stage bootloader to
populate some useful FDT properties for us (notably the /memory node and
KASLR seed) and fetch the DTB that it provides. Combined with the memory
map changes above, this let's us entirely avoid configuring the memory
map explicitly.

== defconfig ==

Most of the board defconfigs and config headers were quite similar, to
simplify maintenance going forward, all the fully generic boards (sdm845
and qcs404-evb so far) are adapted to use the new qcom_defconfig. Going
forward, all new Qualcomm boards should be supported by this defconfig.
A notable exception is for specific usecases (like U-Boot as the primary
bootloader).

== The older dragonboards ==

The db410c and db820c both have some custom board init code, as a result
they aren't yet binary compatible. mach-snapdragon is adjusted so
that all the necessary config options (e.g. CONFIG_SYS_BOARD) can be set
from their defconfigs, this makes it possible to enable support for new
boards without introducing additional config options.

The db410c can run U-Boot either chainloaded like the other boards, or
as a first-stage bootloader replacing aboot. However it was hardcoded to
only build for the latter option. This series introduces a new
"chainloaded" defconfig to enable easier testing via fastboot.

== dynamic environment variables ==

This series also introduces runtime-allocated load addresses via the lmb
allocator. This allows for booting on boards with vastly different
memory layouts without any pre-calculation or macro magic in the config
header. This feature is based on similar code in mach-apple.

The soc, board, and fdtfile environment variables are also generated
automatically. Many Qualcomm boards follow a similar scheme for DTB
naming such that the name can often be derived from the root compatible
properties. This is intended to cover the most common cases and be a
simple solution for booting generic distro images without having to
explicitly choose the right DTB. The U-Boot DTS can be tweaked if
necessary to produce the correct name, the variable can be overwritten,
or a bootloader like GRUB can load the devicetree instead.

== Upstream DT ==

All Qualcomm boards have had their devicetree files rewritten to be
based on the upstream SoC/PMIC DTSI files. Previous patch series made
the necessary driver adjustments to fully support the upstream DT
format. All future Qualcomm boards should use upstream DTS by default.

---

I have tested this series on the Dragonboard410c, Dragonboard820c, and
Dragonboard845c. I unfortunately don't have access to a QCS404 EVB board
to test.

This series is based on the qcom-next branch [1] and depends on my PMIC
fixes series [2], an integration branch for testing can be found at [3].
The non-qualcomm-specific changes (patches 1, 2, and 3) don't have any
dependencies.

[1]: https://source.denx.de/u-boot/custodians/u-boot-snapdragon
[2]: https://lore.kernel.org/u-boot/20231114-b4-qcom-dt-compat-v3-0-88a92f8f00ba@linaro.org/
[3]: https://source.denx.de/u-boot/custodians/u-boot-snapdragon/-/tree/b4/qcom-common-target

# Describe the purpose of this series. The information you put here
# will be used by the project maintainer to make a decision whether
# your patches should be reviewed, and in what priority order. Please be
# very detailed and link to any relevant discussions or sites that the
# maintainer can review to better understand your proposed changes. If you
# only have a single patch in your series, the contents of the cover
# letter will be appended to the "under-the-cut" portion of the patch.

# Lines starting with # will be removed from the cover letter. You can
# use them to add notes or reminders to yourself. If you want to use
# markdown headers in your cover letter, start the line with ">#".

# You can add trailers to the cover letter. Any email addresses found in
# these trailers will be added to the addresses specified/generated
# during the b4 send stage. You can also run "b4 prep --auto-to-cc" to
# auto-populate the To: and Cc: trailers based on the code being
# modified.

To: Neil Armstrong <neil.armstrong@linaro.org>
To: Sumit Garg <sumit.garg@linaro.org>
To: Ramon Fried <rfried.dev@gmail.com>
Cc: Marek Vasut <marex@denx.de>
To: Dzmitry Sankouski <dsankouski@gmail.com>
To: Caleb Connolly <caleb.connolly@linaro.org>
To: Peng Fan <peng.fan@nxp.com>
To: Jaehoon Chung <jh80.chung@samsung.com>
To: Rayagonda Kokatanur <rayagonda.kokatanur@broadcom.com>
To: Lukasz Majewski <lukma@denx.de>
To: Sean Anderson <seanga2@gmail.com>
To: Jorge Ramirez-Ortiz <jorge.ramirez.ortiz@gmail.com>
To: Stephan Gerhold <stephan@gerhold.net>
Cc:  <u-boot@lists.denx.de>

---
Changes in v2:
- EDITME: describe what is new in this series revision.
- EDITME: use bulletpoints and terse descriptions.
- Link to v1: https://lore.kernel.org/r/20231121-b4-qcom-common-target-v1-0-9492198e0c15@linaro.org


--- b4-submit-tracking ---
# This section is used internally by b4 prep for tracking purposes.
{
  "series": {
    "revision": 2,
    "change-id": "20231114-b4-qcom-common-target-4f9e17463ee5",
    "prefixes": [],
    "history": {
      "v1": [
        "20231121-b4-qcom-common-target-v1-0-9492198e0c15@linaro.org"
      ]
    }
  }
}