diff --git a/Documentation/devicetree/bindings/soc/ti/wkup_m3_ipc.txt b/Documentation/devicetree/bindings/soc/ti/wkup_m3_ipc.txt
index 4cdbb60fd0d0bace26aed3155b7dcf942545275b..2d6c66ba1cdaf76dc9cfa130403501524de30e80 100644 (file)
ti,vtt-gpio-pin = <7>;
...
};
+
+VTT Toggle using any GPIO
+----------------------------------
+Supported by: AM437x ONLY
+Used on: AM437x GP EVM
+
+Many of the pins on AM437x have the ability to configure both normal and
+sleep states. Because of this it is possible to use any pin with a
+corresponding CTRL_CONF_* register in the control module and the
+DS_PAD_CONFIG bits to toggle the VTT regulator enable pin. The DS state of
+the pin must be configured such that the pin disables the VTT regulator. The
+normal state of the pin must be configured such that the VTT regulator is
+enabled by the state alone. This is because the VTT regulator must be enabled
+before context is restored to the controlling GPIO.
+
+Optional properties:
+- ti,set-io-isolation: Indicates that the IO's should be placed into
+ isolation and the DS_PAD_CONFIG values should be
+ used during suspend.
+
+Example:
+
+On the AM437x GP EVM, the VTT enable line must be held low to disable VTT
+regulator and held high to enable, so the following pinctrl entry is used.
+The DS pull is enabled which uses a pull down by default and DS off mode is
+used which outputs a low by default. For the normal state, a pull up is
+specified so that the VTT enable line gets pulled high immediately after
+the DS states are removed upon exit from DeepSleep0.
+
+ &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: wkup_m3_ipc@1324 {
+ compatible = "ti,am4372-wkup-m3-ipc";
+ ...
+ ...
+ ti,set-io-isolation;
+ ...
+ };