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Markus Schneider-Pargmann (TI.com) <msp@baylibre.com> says: 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. Previous versions: 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 v7: https://lore.kernel.org/r/20250421-topic-mcan-wakeup-source-v6-12-v7-0-1b7b916c9832@baylibre.com v8: https://lore.kernel.org/r/20250812-topic-mcan-wakeup-source-v6-12-v8-0-6972a810d63b@baylibre.com v9: https://lore.kernel.org/r/20250820-topic-mcan-wakeup-source-v6-12-v9-0-0ac13f2ddd67@baylibre.com Changes in v10: - Change dt-binding to be able to set pinctrl-names = "default", "wakeup"; - Fix wording in the dt-binging - Fix mcan commit message to have correct naming of the SoC - Change function name from m_can_class_setup_optional_pinctrl() to m_can_class_parse_pinctrl() Changes in v9: - Update the binding to accept the sleep pinctrl state which is already in use by other devicetrees - Modify suspend/resume to not set the sleep state if wakeup is enabled and a wakeup pinctrl state is present. If wakeup pinctrl is active this should be kept enabled even after suspend - Modify m_can_set_wol() to use pinctrl_pm_select_default_state() to get rid of the manually managed default pinctrl. 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(). Link: https://patch.msgid.link/20251001-topic-mcan-wakeup-source-v6-12-v10-0-4ab508ac5d1e@baylibre.com Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
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