linux-kernel - [PATCH v3 0/2] support Linux reboot modes in syscon-reboot

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Message-Id: <20250227-syscon-reboot-reset-mode-v3-0-959ac53c338a@linaro.org>
Date: Thu, 27 Feb 2025 10:46:12 +0000
From: André Draszik <andre.draszik@...aro.org>
To: Sebastian Reichel <sre@...nel.org>, Rob Herring <robh@...nel.org>, 
 Krzysztof Kozlowski <krzk+dt@...nel.org>, 
 Conor Dooley <conor+dt@...nel.org>
Cc: Peter Griffin <peter.griffin@...aro.org>, 
 Tudor Ambarus <tudor.ambarus@...aro.org>, 
 Will McVicker <willmcvicker@...gle.com>, kernel-team@...roid.com, 
 linux-pm@...r.kernel.org, devicetree@...r.kernel.org, 
 linux-kernel@...r.kernel.org, 
 André Draszik <andre.draszik@...aro.org>
Subject: [PATCH v3 0/2] support Linux reboot modes in syscon-reboot

This series teaches syscon-reboot some of Linux' different reboot
modes.

Linux supports a couple different reboot modes, but syscon-reboot
doesn't distinguish between them and issues the same syscon register
write irrespective of the reboot mode requested by the kernel.

This is a problem when platforms want to do a cold reboot most of the
time, which could e.g. wipe RAM etc, but also want to support rebooting
while keeping RAM contents in certain cases.

One example of such a platform is Google Pixel.

DTs can now specify the existing properties prefixed with one of the
Linux reboot modes. All the changes to support this are optional and
opt-in, platforms that don't, or don't specify a register/value/mask
pair for a specific mode will behave just as before.

Signed-off-by: André Draszik <andre.draszik@...aro.org>
---
Changes in v3:
- support <reset-mode>-reg in driver, not just in binding, doh...
- correctly parse <reset-mode>-offset
- add a comment for all the BUILD_BUG_ON() checks
- Link to v2: https://lore.kernel.org/r/20250226-syscon-reboot-reset-mode-v2-0-f80886370bb7@linaro.org

Changes in v2:
- fix whitespace issues in binding
- Link to v1: https://lore.kernel.org/r/20250226-syscon-reboot-reset-mode-v1-0-91c1b62166ae@linaro.org

---
André Draszik (2):
      dt-bindings: reset: syscon-reboot: support reset modes
      power: reset: syscon-reboot: support different reset modes

 .../bindings/power/reset/syscon-reboot.yaml        | 74 +++++++++++++++++
 drivers/power/reset/syscon-reboot.c                | 96 +++++++++++++++++++---
 2 files changed, 159 insertions(+), 11 deletions(-)
---
base-commit: 0226d0ce98a477937ed295fb7df4cc30b46fc304
change-id: 20250226-syscon-reboot-reset-mode-566588b847e1

Best regards,
-- 
André Draszik <andre.draszik@...aro.org>