Hi,

This series adds support for wakeup capabilities to the m_can driver, which 
is necessary for enabling Partial-IO functionality on am62, am62a, and am62p 
SoCs. It implements the wake-on-lan interface for m_can devices and handles 
the pinctrl states needed for wakeup functionality.

am62, am62a and am62p support Partial-IO, a low power system state in which 
nearly everything is turned off except the pins of the CANUART group. This group
contains mcu_mcan0, mcu_mcan1, wkup_uart0 and mcu_uart0 devices.

To support mcu_mcan0 and mcu_mcan1 wakeup for the mentioned SoCs, the
series introduces a notion of wake-on-lan for m_can. If the user decides
to enable wake-on-lan for a m_can device, the device is set to wakeup
enabled. A 'wakeup' pinctrl state is selected to enable wakeup flags for
the relevant pins. If wake-on-lan is disabled the default pinctrl is
selected.

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. This series (m_can driver): Implements device-specific wakeup functionality
   for m_can devices, allowing them to be set as wakeup sources.

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/v6.17?ref_type=heads

3. TI-SCI firmware series: Implements the firmware interface to enter Partial-IO
   mode when appropriate wakeup sources are enabled.
   https://gitlab.baylibre.com/msp8/linux/-/tree/topic/tisci-partialio/v6.17?ref_type=heads

Devicetree Bindings
-------------------
The wakeup-source property is used with references to
system-idle-states. This depends on the dt-schema pull request that adds
bindings for system-idle-states and updates the binding for wakeup-source:
  https://github.com/devicetree-org/dt-schema/pull/150

This is merged now and upstream in dt-schema.

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/v6.17?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

I tested these patches on am62-lp-sk.

Best,
Markus

Previous versions:
 v1: https://lore.kernel.org/lkml/20240523075347.1282395-1-msp@baylibre.com/ (local)
 v2: https://lore.kernel.org/lkml/20240729074135.3850634-1-msp@baylibre.com/ (local)
 v3: https://lore.kernel.org/lkml/20241011-topic-mcan-wakeup-source-v6-12-v3-0-9752c714ad12@baylibre.com (local)
 v4: https://lore.kernel.org/r/20241015-topic-mcan-wakeup-source-v6-12-v4-0-fdac1d1e7aa6@baylibre.com (local)
 v5: https://lore.kernel.org/r/20241028-topic-mcan-wakeup-source-v6-12-v5-0-33edc0aba629@baylibre.com (local)
 v6: https://lore.kernel.org/r/20241219-topic-mcan-wakeup-source-v6-12-v6-0-1356c7f7cfda@baylibre.com (local)
 v7: https://lore.kernel.org/r/20250421-topic-mcan-wakeup-source-v6-12-v7-0-1b7b916c9832@baylibre.com (local)

Changes in v8:
 - Rebase to v6.17-rc1

Changes in v7:
 - Separate this series from "firmware: ti_sci: Partial-IO support"
   again as was requested internally
 - All DT changes are now in their own series to avoid conflicts
 - wakeup-source definition in the m_can binding is now only an
   extension to the dt-schema binding and a pull request was created

Changes in v6:
 - Rebased to v6.13-rc1
 - After feedback of the other Partial-IO series, I updated this series
   and removed all use of regulator-related patches.
 - wakeup-source is now not only a boolean property but can also be a
   list of power states in which the device is wakeup capable.

Changes in v5:
 - Make the check of wol options nicer to read

Changes in v4:
 - Remove leftover testing code that always returned -EIO in a specific
 - Redesign pincontrol setup to be easier understandable and less nested
 - Fix missing parantheses around wol_enable expression
 - Remove | from binding description

Changes in v3:
 - Rebase to v6.12-rc1
 - Change 'wakeup-source' to only 'true'
 - Simplify m_can_set_wol by returning early on error
 - Add vio-suuply binding and handling of this optional property.
   vio-supply is used to reflect the SoC architecture and which power
   line powers the m_can unit. This is important as some units are
   powered in special low power modes.

Changes in v2:
 - Rebase to v6.11-rc1
 - Squash these two patches for the binding into one:
   dt-bindings: can: m_can: Add wakeup-source property
   dt-bindings: can: m_can: Add wakeup pinctrl state
 - Add error handling to multiple patches of the m_can driver
 - Add error handling in m_can_class_allocate_dev(). This also required
   to add a new patch to return error pointers from
   m_can_class_allocate_dev().

Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
---
Markus Schneider-Pargmann (4):
      dt-bindings: can: m_can: Add wakeup properties
      can: m_can: Map WoL to device_set_wakeup_enable
      can: m_can: Return ERR_PTR on error in allocation
      can: m_can: Support pinctrl wakeup state

 .../devicetree/bindings/net/can/bosch,m_can.yaml   |  22 ++++
 drivers/net/can/m_can/m_can.c                      | 111 ++++++++++++++++++++-
 drivers/net/can/m_can/m_can.h                      |   4 +
 drivers/net/can/m_can/m_can_pci.c                  |   4 +-
 drivers/net/can/m_can/m_can_platform.c             |   4 +-
 drivers/net/can/m_can/tcan4x5x-core.c              |   4 +-
 6 files changed, 140 insertions(+), 9 deletions(-)
---
base-commit: 8f5ae30d69d7543eee0d70083daf4de8fe15d585
change-id: 20241009-topic-mcan-wakeup-source-v6-12-8c1d69931bd8

Best regards,
-- 
Markus Schneider-Pargmann [off-list ref]