From: Dave Gerlach <[email protected]>
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 <[email protected]>
Signed-off-by: Drew Fustini <[email protected]>
---
.../bindings/soc/ti/wkup_m3_ipc.txt | 46 +++++++++++++++++++
1 file changed, 46 insertions(+)
diff --git a/Documentation/devicetree/bindings/soc/ti/wkup_m3_ipc.txt b/Documentation/devicetree/bindings/soc/ti/wkup_m3_ipc.txt
index 4cdbb60fd0d0..df6b600abf4c 100644
--- a/Documentation/devicetree/bindings/soc/ti/wkup_m3_ipc.txt
+++ b/Documentation/devicetree/bindings/soc/ti/wkup_m3_ipc.txt
@@ -89,3 +89,49 @@ Example:
ti,vtt-gpio-pin = <7>;
...
};
+
+
+IO Isolation
+============
+Supported by: AM43xx SoCs
+
+It is possible to configure any pin with a corresponding CTRL_CONF_*
+register in the control module to use the states defined in the DS_PAD_CONFIG
+bits by enabling IO isolation on the SoC. The 'ti,set-io-isolation' property
+tells the wkup_m3_ipc driver to enable IO isolation late in the suspend path
+after all drivers have been disabled.
+
+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 (VTT Toggle using any GPIO on am437x-gp-evm):
+-----------------------------------------------------
+
+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;
+ ...
+ };
--
2.32.0