On Tue, Apr 12, 2022 at 07:06:40PM -0700, Drew Fustini wrote:
> Add documentation for the ti,io-isolation DT property on the wkup_m3_ipc
> node which tells the wkup_m3_ipc driver to use the wkup_m3 to enable
> IO Isolation during low power mode transitions on am43xx platforms.
>
> Signed-off-by: Dave Gerlach <d-gerlach@xxxxxx>
> [dfustini: convert to YAML, make DTS example that passes check]
> Signed-off-by: Drew Fustini <dfustini@xxxxxxxxxxxx>
> ---
> .../bindings/soc/ti/wkup-m3-ipc.yaml | 68 +++++++++++++++++--
> 1 file changed, 63 insertions(+), 5 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/soc/ti/wkup-m3-ipc.yaml b/Documentation/devicetree/bindings/soc/ti/wkup-m3-ipc.yaml
> index 7f4a75c5fcaa..30a65b75c024 100644
> --- a/Documentation/devicetree/bindings/soc/ti/wkup-m3-ipc.yaml
> +++ b/Documentation/devicetree/bindings/soc/ti/wkup-m3-ipc.yaml
> @@ -24,14 +24,22 @@ description: |+
> A wkup_m3_ipc device node is used to represent the IPC registers within an
> SoC.
>
> - Support for VTT Toggle
> - ==================================
> + 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.
Can't this feature be implied from the compatible string?
> +
> properties:
> compatible:
> enum:
> @@ -63,6 +71,14 @@ properties:
> $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.
> +
> required:
> - compatible
> - reg
> @@ -74,21 +90,63 @@ additionalProperties: false
>
> examples:
> - |
> + /* Example for AM335x SoC */
> soc {
> #address-cells = <1>;
> #size-cells = <1>;
>
> - mailbox: mailbox {
> + am335x_mailbox: mailbox {
> #mbox-cells = <1>;
> };
>
> - wkup_m3_ipc: wkup_m3_ipc@1324 {
> + wkup_m3_ipc@1324 {
> compatible = "ti,am3352-wkup-m3-ipc";
> reg = <0x1324 0x24>;
> interrupts = <78>;
> ti,rproc = <&wkup_m3>;
> - mboxes = <&mailbox &mbox_wkupm3>;
> + mboxes = <&am335x_mailbox &mbox_wkupm3>;
> ti,vtt-gpio-pin = <7>;
> };
> };
> +
> + - |
> + /*
> + * 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;
> + };
> + };
> +
> ...
> --
> 2.32.0
>
>
