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From:   Drew Fustini <dfustini@baylibre.com>
To:     Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzk+dt@kernel.org>,
        Dave Gerlach <d-gerlach@ti.com>,
        Tony Lindgren <tony@atomide.com>, Nishanth Menon <nm@ti.com>,
        Santosh Shilimkar <ssantosh@kernel.org>
Cc:     devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org, Drew Fustini <dfustini@baylibre.com>
Subject: [PATCH v2 1/2] dt-bindings: wkup-m3-ipc: Add vtt toggle gpio pin property
Date:   Sat,  9 Apr 2022 14:12:14 -0700
Message-Id: <20220409211215.2529387-2-dfustini@baylibre.com>
In-Reply-To: <20220409211215.2529387-1-dfustini@baylibre.com>
References: <20220409211215.2529387-1-dfustini@baylibre.com>
MIME-Version: 1.0
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Precedence: bulk

Document Wakeup M3 IPC property that indicates a GPIO pin is connected
to the enable pin on DDR VTT regulator and can be toggled during low
power mode transitions.

Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
[dfustini: converted to YAML, removed unnecessary "ti,needs-vtt-toggle"]
Signed-off-by: Drew Fustini <dfustini@baylibre.com>
---
 .../devicetree/bindings/soc/ti/wkup-m3-ipc.yaml     | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/Documentation/devicetree/bindings/soc/ti/wkup-m3-ipc.yaml b/Documentation/devicetree/bindings/soc/ti/wkup-m3-ipc.yaml
index d855c01ce61c..7f4a75c5fcaa 100644
--- a/Documentation/devicetree/bindings/soc/ti/wkup-m3-ipc.yaml
+++ b/Documentation/devicetree/bindings/soc/ti/wkup-m3-ipc.yaml
@@ -24,6 +24,14 @@ description: |+
   A wkup_m3_ipc device node is used to represent the IPC registers within an
   SoC.
 
+  Support for VTT Toggle
+  ==================================
+  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.
+
 properties:
   compatible:
     enum:
@@ -51,6 +59,10 @@ properties:
       mbox_wkupm3 child node.
     maxItems: 1
 
+  ti,vtt-gpio-pin:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description: GPIO pin connected to enable pin on VTT regulator
+
 required:
   - compatible
   - reg
@@ -76,6 +88,7 @@ examples:
            interrupts = <78>;
            ti,rproc = <&wkup_m3>;
            mboxes = <&mailbox &mbox_wkupm3>;
+           ti,vtt-gpio-pin = <7>;
         };
     };
 ...
-- 
2.32.0