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Date: Thu, 14 Apr 2022 07:49:40 -0500
From: Dave Gerlach <d-gerlach@...com>
To: Rob Herring <robh@...nel.org>, Drew Fustini <dfustini@...libre.com>
CC: Krzysztof Kozlowski <krzk+dt@...nel.org>,
Tony Lindgren <tony@...mide.com>, Nishanth Menon <nm@...com>,
Santosh Shilimkar <ssantosh@...nel.org>,
<devicetree@...r.kernel.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] dt-bindings: wkup-m3-ipc: Add ti,io-isolation
property
Hi,
On 4/14/22 07:34, Rob Herring wrote:
> 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.
>>
$subject should be 'ti,set-io-isolation'.
>> Signed-off-by: Dave Gerlach <d-gerlach@...com>
>> [dfustini: convert to YAML, make DTS example that passes check]
>> Signed-off-by: Drew Fustini <dfustini@...libre.com>
>> ---
>> .../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?
All AM437x SoCs support it, but it may be enabled/disabled on different
boards. For example, this will be set for am437x-gp-evm, but not
am43x-epos-evm.
Regards,
Dave
>
>> +
>> 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@...4 {
>> + wkup_m3_ipc@...4 {
>> 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@...4 {
>> + 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
>>
>>
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