linux-kernel - [PATCH 0/3] Add AIC support for A7-A11 SoCs

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Message-ID: <20240829092610.89731-1-towinchenmi@gmail.com>
Date: Thu, 29 Aug 2024 17:03:10 +0800
From: Nick Chan <towinchenmi@...il.com>
To: Hector Martin <marcan@...can.st>,
	Sven Peter <sven@...npeter.dev>,
	Alyssa Rosenzweig <alyssa@...enzweig.io>,
	Thomas Gleixner <tglx@...utronix.de>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	asahi@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org
Cc: ~postmarketos/upstreaming@...ts.sr.ht,
	Nick Chan <towinchenmi@...il.com>
Subject: [PATCH 0/3] Add AIC support for A7-A11 SoCs

Hi,

This series is a second attempt at adding support for A7-A11 SoCs to
Linux, it is based on a previous attempt, which you can find at [1].
However, there have been quite a bit of changes.

First, the boot process has changed, now, the boot process includes
a "1337" version of checkra1n [2], a custom PongoOS binary [3], and
a modified version of m1n1 [4]. The kernel is appended to m1n1 and loaded
by it.

This attempt also supports SMP, which has uncovered some differences
in the A7-A11 AIC. Namely, although A11 supported fast IPI, it only
supported "global" fast IPIs via SYS_IMP_APL_IPI_RR_GLOBAL_EL1,
and SYS_IMP_APL_IPI_RR_LOCAL_EL1 does not exist on A11. As a result,
there are now three feature levels:

A7 - A10: No fast IPI
A11: "Global" fast IPI
M1: Global and Local fast IPI

Each feature level is strictly an extension of the previous, for example,
M1 will also work with the A7-A10 compatible. As a result, the
modifications only includes if'ing out of features, in order to make
the existing driver work on older SoCs.

The A10(X) contains P-core and E-core pairs where only one core in each
pair may be active at one time, controlled by CPU frequency. A RFC patch
will be posted to disable 32-bit executable support on A10(X), as it only
supported 16KB page size anyways. However, such a patch is not required
to run AArch64 Linux on A10. At worst, any attempt to run 32-bit
executables will result in the process crashing.

Initial device trees will be posted in a later patch series, likely when
the AIC modifications are accepted.

Asahi Linux downstream kernel note:
These patches will not work with the Asahi Linux downstream kernel,
as these earlier SoCs do not support state retention across deep WFI,
which results in the CPUs going back to RVBAR on cpuidle.

[1]: https://lore.kernel.org/asahi/20221007200022.22844-1-konrad.dybcio@somainline.org/
[2]: https://checkra.in/1337
[3]: https://github.com/asdfugil/pongoOS/tree/mini
[4]: https://github.com/asdfugil/m1n1-idevice

Nick Chan (3):
  dt-bindings: apple,aic: Document A7-A11 compatibles
  irqchip/apple-aic: Only access IPI sysregs when use_fast_ipi is true
  irqchip/apple-aic: Add a new "Global fast IPIs only" feature level

 .../interrupt-controller/apple,aic.yaml       | 15 ++++--
 drivers/irqchip/irq-apple-aic.c               | 49 ++++++++++++++-----
 2 files changed, 48 insertions(+), 16 deletions(-)

-- 
2.46.0