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+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/soc/ti/wkup-m3-ipc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Wakeup M3 IPC device
+
+maintainers:
+ - Dave Gerlach <d-gerlach@ti.com>
+ - Drew Fustini <dfustini@baylibre.com>
+
+description: |+
+ The TI AM33xx and AM43xx family of devices use a small Cortex M3 co-processor
+ (commonly referred to as Wakeup M3 or CM3) to help with various low power tasks
+ that cannot be controlled from the MPU, like suspend/resume and certain deep
+ C-states for CPU Idle. Once the wkup_m3_ipc driver uses the wkup_m3_rproc driver
+ to boot the wkup_m3, it handles communication with the CM3 using IPC registers
+ present in the SoC's control module and a mailbox. The wkup_m3_ipc exposes an
+ API to allow the SoC PM code to execute specific PM tasks.
+
+ Wkup M3 Device Node
+ ====================
+ A wkup_m3_ipc device node is used to represent the IPC registers within an
+ SoC.
+
+ Support for VTT Toggle with GPIO pin
+ ====================================
+ On some boards like the AM335x EVM-SK and the AM437x GP EVM, a GPIO pin is
+ connected to the enable pin on the DDR VTT regulator. This allows the
+ regulator to be disabled upon suspend and enabled upon resume. Please note
+ that the GPIO pin must be part of the GPIO0 module as only this GPIO module
+ is in the wakeup power domain.
+
+ Support for IO Isolation
+ ========================
+ On AM437x SoCs, certain pins can be forced into an alternate state when IO
+ isolation is activated. Those pins have pad control registers prefixed by
+ 'CTRL_CONF_' that contain DS0 (e.g. deep sleep) configuration bits that can
+ override the pin's existing bias (pull-up/pull-down) and value (high/low) when
+ IO isolation is active.
+
+ Support for I2C PMIC Voltage Scaling
+ ====================================
+ It is possible to pass the name of a binary file to load into the CM3 memory.
+ The binary data is the I2C sequences for the CM3 to send out to the PMIC
+ during low power mode entry.
+
+properties:
+ compatible:
+ enum:
+ - ti,am3352-wkup-m3-ipc # for AM33xx SoCs
+ - ti,am4372-wkup-m3-ipc # for AM43xx SoCs
+
+ reg:
+ description:
+ The IPC register address space to communicate with the Wakeup M3 processor
+ maxItems: 1
+
+ interrupts:
+ description: wkup_m3 interrupt that signals the MPU
+ maxItems: 1
+
+ ti,rproc:
+ $ref: /schemas/types.yaml#/definitions/phandle
+ description:
+ phandle to the wkup_m3 rproc node so the IPC driver can boot it
+
+ mboxes:
+ description:
+ phandles used by IPC framework to get correct mbox
+ channel for communication. Must point to appropriate
+ mbox_wkupm3 child node.
+ maxItems: 1
+
+ firmware-name:
+ description:
+ Name of binary file with I2C sequences for PMIC voltage scaling
+
+ ti,vtt-gpio-pin:
+ $ref: /schemas/types.yaml#/definitions/uint32
+ description: GPIO pin connected to enable pin on VTT regulator
+
+ ti,set-io-isolation:
+ type: boolean
+ description:
+ If this property is present, then the wkup_m3_ipc driver will instruct
+ the CM3 firmware to activate IO isolation when suspending to deep sleep.
+ This can be leveraged by a board design to put other devices on the board
+ into a low power state.
+
+allOf:
+ - if:
+ properties:
+ compatible:
+ not:
+ contains:
+ const: ti,am4372-wkup-m3-ipc
+ then:
+ properties:
+ ti,set-io-isolation: false
+
+required:
+ - compatible
+ - reg
+ - interrupts
+ - ti,rproc
+ - mboxes
+
+additionalProperties: false
+
+examples:
+ - |
+ /* Example for AM335x SoC */
+ soc {
+ #address-cells = <1>;
+ #size-cells = <1>;
+
+ am335x_mailbox: mailbox {
+ #mbox-cells = <1>;
+ };
+
+ wkup_m3_ipc@1324 {
+ compatible = "ti,am3352-wkup-m3-ipc";
+ reg = <0x1324 0x24>;
+ interrupts = <78>;
+ ti,rproc = <&wkup_m3>;
+ mboxes = <&am335x_mailbox &mbox_wkupm3>;
+ ti,vtt-gpio-pin = <7>;
+ firmware-name = "am335x-evm-scale-data.bin";
+ };
+ };
+
+ - |
+ /*
+ * Example for AM473x SoC:
+ * On the AM437x-GP-EVM board, gpio5_7 is wired to enable pin of the DDR VTT
+ * regulator. The 'ddr_vtt_toggle_default' pinmux node configures gpio5_7
+ * for pull-up during normal system operation. However, the DS0 (deep sleep)
+ * state of the pin is configured for pull-down and thus the VTT regulator
+ * will be disabled to save power when IO isolation is active. Note that
+ * this method is an alternative to using the 'ti,vtt-gpio-pin' property.
+ */
+ #include <dt-bindings/pinctrl/am43xx.h>
+ soc {
+ #address-cells = <1>;
+ #size-cells = <1>;
+
+ am437x_mailbox: mailbox {
+ #mbox-cells = <1>;
+ };
+
+ am43xx_pinmux {
+ pinctrl-names = "default";
+ pinctrl-0 = <&ddr3_vtt_toggle_default>;
+
+ ddr3_vtt_toggle_default: ddr_vtt_toggle_default {
+ pinctrl-single,pins = <
+ 0x25C (DS0_PULL_UP_DOWN_EN | PIN_OUTPUT_PULLUP | DS0_FORCE_OFF_MODE | MUX_MODE7)
+ >;
+ };
+ };
+
+ wkup_m3_ipc@1324 {
+ compatible = "ti,am4372-wkup-m3-ipc";
+ reg = <0x1324 0x24>;
+ interrupts = <78>;
+ ti,rproc = <&wkup_m3>;
+ mboxes = <&am437x_mailbox &mbox_wkupm3>;
+ ti,set-io-isolation;
+ firmware-name = "am43x-evm-scale-data.bin";
+ };
+ };
+
+...