Document the new platform build options for the MSM8916 port which now
supports multiple similar Qualcomm SoCs:
- Snapdragon 410 (PLAT=msm8916) as before
- Snapdragon 615 (PLAT=msm8939)
- Snapdragon 210 (PLAT=msm8909)
- Snapdragon X5 Modem (PLAT=mdm9607)
The latter two use AArch32-only ARM Cortex-A7 cores that only support
using BL32/SP_MIN and not BL31 on AArch64.
Change-Id: I9fffe60dd0ad2acc18f006f11e91854b9e8dcb8f
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Update the MSM8916 platform documentation with the new build options
introduced in the previous changes:
- AArch32 (BL32/SP_MIN)
- UART selection
While at it, also document the build options that allow changing the
memory addresses (PRELOADED_BL33_BASE, BL31_BASE, BL32_BASE).
Change-Id: I2370c8264982317693f69fda0b03a255f12bafe2
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
The Qualcomm Snapdragon 410 is Qualcomm's first 64-bit SoC, released
in 2014 with four ARM Cortex-A53 cores. There are differents variants
(MSM8916, APQ8016(E), ...) that are all very similar. A popular device
based on APQ8016E is the DragonBoard 410c single-board computer,
but the SoC is also used in various mid-range smartphones/tablets.
This commit adds documentation for a minimal, community-maintained port
of TF-A/BL31 for MSM8916. The actual platform port is added in the
following four separate small commits to simplify the review process.
The code is primarily based on the information from the public
Snapdragon 410E Technical Reference Manual [1], combined with a lot of
trial and error to actually make it work.
Note that this port is a pure community effort without any
commercial interests and is not related to Qualcomm in any way.
The main motivation for this port is to have a minimal, updatable
firmware since this old chip does not receive many updates anymore from
Qualcomm. It works quite well for many use cases so I am willing to
maintain it as a "code owner". I have also added Nikita Travkin as
second code owner to help with reviews.
The main limitation so far is the lack of memory protection for TF-A.
This is similar to the ports for the Raspberry Pi but in this case not
a lack of hardware support but rather a lack of documentation. However,
this does not limit the usefulness of the port when used as a minimal
PSCI implementation.
[1]: https://developer.qualcomm.com/download/sd410/snapdragon-410e-technical-reference-manual.pdf
Change-Id: I676adf86061638cfc2f3ae8615470d145e84f172
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
