Message-Id: <20251030-topic-am62-partialio-v6-12-b4-v9-0-074f55d9c16b@baylibre.com>
Date: Thu, 30 Oct 2025 10:26:07 +0100
From: "Markus Schneider-Pargmann (TI.com)" <msp@...libre.com>
To: Nishanth Menon <nm@...com>, Tero Kristo <kristo@...nel.org>, 
 Santosh Shilimkar <ssantosh@...nel.org>
Cc: Vishal Mahaveer <vishalm@...com>, Kevin Hilman <khilman@...libre.com>, 
 Dhruva Gole <d-gole@...com>, Sebin Francis <sebin.francis@...com>, 
 Kendall Willis <k-willis@...com>, Akashdeep Kaur <a-kaur@...com>, 
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 "Markus Schneider-Pargmann (TI.com)" <msp@...libre.com>
Subject: [PATCH v9 0/3] firmware: ti_sci: Partial-IO support

Hi,

This series adds support for Partial-IO to the ti-sci driver,
implementing the firmware interface necessary to enter this low power
state. It processes the wakeup-source properties from the devicetree and
communicates with the system firmware to enter Partial-IO mode when
appropriate wakeup sources are enabled.

Partial-IO Overview
------------------
Partial-IO is a low power system state in which nearly everything is
turned off except the pins of the CANUART group (mcu_mcan0, mcu_mcan1,
wkup_uart0 and mcu_uart0). These devices can trigger a wakeup of the
system on pin activity. Note that this does not resume the system as the
DDR is off as well. So this state can be considered a power-off state
with wakeup capabilities.

A documentation can also be found in section 6.2.4 in the TRM:
  https://www.ti.com/lit/pdf/spruiv7

Implementation Details
----------------------
The complete Partial-IO feature requires three coordinated series, each
handling a different aspect of the implementation:

1. [MERGED] m_can driver series: Implements device-specific wakeup functionality
   for m_can devices, allowing them to be set as wakeup sources. This is
   now available in linux-next.
   https://lore.kernel.org/r/20251001-topic-mcan-wakeup-source-v6-12-v10-0-4ab508ac5d1e@baylibre.com

2. Devicetree series: Defines system states and wakeup sources in the
   devicetree for am62, am62a and am62p.
   https://gitlab.baylibre.com/msp8/linux/-/tree/topic/am62-dt-partialio/v6.18?ref_type=heads
   https://lore.kernel.org/r/20251030-topic-am62-dt-partialio-v6-15-v4-0-6b520dfa8591@baylibre.com

3. This series (TI-SCI firmware): Implements the firmware interface to
   enter Partial-IO mode when appropriate wakeup sources are enabled.

Testing
-------
A test branch is available here that includes all patches required to
test Partial-IO:

https://gitlab.baylibre.com/msp8/linux/-/tree/integration/am62-partialio/v6.18?ref_type=heads

After enabling Wake-on-LAN the system can be powered off and will enter
the Partial-IO state in which it can be woken up by activity on the
specific pins:
    ethtool -s can0 wol p
    ethtool -s can1 wol p
    poweroff

These patches are tested on am62-lp-sk.

Best,
Markus

Previous versions "firmware: ti_sci: Partial-IO support":
 v1: https://lore.kernel.org/lkml/20240523080225.1288617-1-msp@baylibre.com/
 v2: https://lore.kernel.org/lkml/20240729080101.3859701-1-msp@baylibre.com/
 v3: https://lore.kernel.org/r/20241012-topic-am62-partialio-v6-13-b4-v3-0-f7c6c2739681@baylibre.com
 v4: https://lore.kernel.org/r/20241219-topic-am62-partialio-v6-12-b4-v4-0-1cb8eabd407e@baylibre.com
 v5: https://lore.kernel.org/r/20250306-topic-am62-partialio-v6-12-b4-v5-0-f9323d3744a2@baylibre.com
 v6: https://lore.kernel.org/r/20250421-topic-am62-partialio-v6-12-b4-v6-0-3b5cefab1339@baylibre.com
 v7: https://lore.kernel.org/r/20250812-topic-am62-partialio-v6-12-b4-v7-0-ac10865c2d87@baylibre.com
 v8: https://lore.kernel.org/r/20251001-topic-am62-partialio-v6-12-b4-v8-0-76a742605110@baylibre.com

Previous versions "can: m_can: Add am62 wakeup support":
 v1: https://lore.kernel.org/lkml/20240523075347.1282395-1-msp@baylibre.com/
 v2: https://lore.kernel.org/lkml/20240729074135.3850634-1-msp@baylibre.com/
 v3: https://lore.kernel.org/lkml/20241011-topic-mcan-wakeup-source-v6-12-v3-0-9752c714ad12@baylibre.com
 v4: https://lore.kernel.org/r/20241015-topic-mcan-wakeup-source-v6-12-v4-0-fdac1d1e7aa6@baylibre.com
 v5: https://lore.kernel.org/r/20241028-topic-mcan-wakeup-source-v6-12-v5-0-33edc0aba629@baylibre.com
 v6: https://lore.kernel.org/r/20241219-topic-mcan-wakeup-source-v6-12-v6-0-1356c7f7cfda@baylibre.com

Changes in v9:
- Rebased to next-20251029

Changes in v8:
 - Add a patch to remove constant 0 argument passing to
   ti_sci_cmd_prepare_sleep
 - Move partial-io functions further up in the file before the first
   static const initializations

Changes in v7:
 - Rebase to v6.17-rc1
 - Update the idle-state-name used to off-wake as introduced in
   dt-schema

Changes in v6:
 - Narrowed down the wakeup-source binding to phandle lists
 - Split off the mcan and DT changes into separate series

Changes in v5:
 - Rebased to v6.14-rc1
 - Merged m_can and ti_sci series to avoid conflicts and show
   dependencies more easily
 - Added definitions of system-states for am62/am62a/am62p
 - Moved wakeup-source definitions into board dts files as they require
   a bit of support on the board.
 - Updated ti_sci support to walk through the wakeup-source phandle
   lists
 - Added pinctrl settings for mcu_mcan0/1 on all boards
 - Minor style updates for ti_sci support for transfers without response
 - Update and move the dt-binding for wakeup-source from the m_can
   binding to the dt-schema repository

Changes in v4:
 - Rebased to v6.13-rc1
 - Removed all regulator related structures from patches and implemented
   the wakeup-source property use instead.

Changes in v3:
 - Remove other modes declared for PREPARE_SLEEP as they probably won't
   ever be used in upstream.
 - Replace the wait loop after sending PREPARE_SLEEP with msleep and do
   an emergency_restart if it exits
 - Remove uarts from DT wakeup sources
 - Split no response handling in ti_sci_do_xfer() into a separate patch
   and use goto instead of if ()
 - Remove DT binding parital-io-wakeup-sources. Instead I am modeling
   the devices that are in the relevant group that are powered during
   Partial-IO with the power supplies that are externally provided to
   the SoC. In this case they are provided through 'vddshv_canuart'. All
   devices using this regulator can be considered a potential wakeup
   source if they are wakeup capable and wakeup enabled.
 - Added devicetree patches adding vcc_3v3_sys regulator and
   vddshv_canuart for am62-lp-sk
 - Add pinctrl entries for am62-lp-sk to add WKUP_EN for mcu_mcan0 and
   mcu_mcan1

Changes in v2:
 - Rebase to v6.11-rc1
 - dt-binding:
    - Update commit message
    - Add more verbose description of the new binding for a better
      explanation.
 - ti_sci driver:
    - Combine ti_sci_do_send() into ti_sci_do_xfer and only wait on a
      response if a flag is set.
    - On failure to enter Partial-IO, do emergency_restart()
    - Add comments
    - Fix small things

Signed-off-by: Markus Schneider-Pargmann (TI.com) <msp@...libre.com>
---
Markus Schneider-Pargmann (TI.com) (3):
      firmware: ti_sci: Remove constant 0 function arguments
      firmware: ti_sci: Support transfers without response
      firmware: ti_sci: Partial-IO support

 drivers/firmware/ti_sci.c | 154 ++++++++++++++++++++++++++++++++++++++++++----
 drivers/firmware/ti_sci.h |   5 ++
 2 files changed, 146 insertions(+), 13 deletions(-)
---
base-commit: c9a389ffad27e7847c69f4d2b67ba56b77190209
change-id: 20241008-topic-am62-partialio-v6-12-b4-c273fbac4447

Best regards,
-- 
Markus Schneider-Pargmann (TI.com) <msp@...libre.com>

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