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From:   Drew Fustini <dfustini@baylibre.com>
To:     =?UTF-8?q?Beno=C3=AEt=20Cousson?= <bcousson@baylibre.com>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Dave Gerlach <d-gerlach@ti.com>, devicetree@vger.kernel.org,
        Drew Fustini <dfustini@baylibre.com>,
        Keerthy <j-keerthy@ti.com>, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org,
        linux-remoteproc@vger.kernel.org,
        Mathieu Poirier <mathieu.poirier@linaro.org>,
        Nishanth Menon <nm@ti.com>, Rob Herring <robh+dt@kernel.org>,
        Santosh Shilimkar <ssantosh@kernel.org>,
        Tony Lindgren <tony@atomide.com>, s-anna@ti.com,
        khilman@baylibre.com
Subject: [PATCH 02/11] dt-bindings: wkup_m3_ipc: Add vtt toggling bindings
Date:   Sat, 19 Feb 2022 13:53:19 -0800
Message-Id: <20220219215328.485660-3-dfustini@baylibre.com>
In-Reply-To: <20220219215328.485660-1-dfustini@baylibre.com>
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From: Dave Gerlach <d-gerlach@ti.com>

Add description of the wkup_m3_ipc DT properties that can be used to
toggle VTT regulator during low power mode transitions.

Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
Signed-off-by: Drew Fustini <dfustini@baylibre.com>
---
 .../bindings/soc/ti/wkup_m3_ipc.txt           | 34 +++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/Documentation/devicetree/bindings/soc/ti/wkup_m3_ipc.txt b/Documentation/devicetree/bindings/soc/ti/wkup_m3_ipc.txt
index 401550487ed6..4cdbb60fd0d0 100644
--- a/Documentation/devicetree/bindings/soc/ti/wkup_m3_ipc.txt
+++ b/Documentation/devicetree/bindings/soc/ti/wkup_m3_ipc.txt
@@ -55,3 +55,37 @@ Example:
 			...
 		};
 	};
+
+Support for VTT Toggle
+==================================
+In order to enable the support for VTT toggle during Suspend/Resume
+sequence needed by some boards (like AM335x EVM-SK & AM437x GP EVM),
+the below DT properties are required. It is possible to toggle VTT
+using one of two methods depending on the SoC being used, either
+GPIO0 toggle (AM335x and AM437x), or any GPIO with DS_PAD_CONFIG
+bits in the control module (AM437x only).
+
+VTT Toggle using GPIO0
+----------------------------------
+Supported by: AM335x and AM437x
+Used on: AM335x EVM-SK
+
+Optional properties:
+- ti,needs-vtt-toggle:	Indicates that the boards requires VTT toggling
+			during suspend/resume.
+- ti,vtt-gpio-pin:	Specifies the GPIO0 pin used for VTT toggle.
+
+Important Note:
+- Here it is assumed that VTT Toggle will be done using a pin on GPIO-0 Instance.
+  It will not work on any other GPIO using the above properties, regardless of
+  which part is being used.
+
+Example:
+	wkup_m3_ipc: wkup_m3_ipc@1324 {
+		compatible = "ti,am3352-wkup-m3-ipc";
+		...
+		...
+		ti,needs-vtt-toggle;
+		ti,vtt-gpio-pin = <7>;
+		...
+	};
-- 
2.32.0