Add iomuxc-lpsr devicetree bindings documentation
Provide documentation context as well an example on
pheriperals that could use pad from either iomuxc controller
supported by iMX7D SoC
Signed-off-by: Adrian Alonso <aalonso@xxxxxxxxxxxxx>
---
Changes for V2: New patch on imx7d iomuxc-lpsr patch series
Changes for V3: Add shared input select register notes
Changes for V4: Resend
Changes for V5:
- Fix spell error
- Remove references of SHARE_INPUT_SELECT_REG flag
Changes for v6: Resend
.../bindings/pinctrl/fsl,imx7d-pinctrl.txt | 63 +++++++++++++++++++++-
1 file changed, 62 insertions(+), 1 deletion(-)
diff --git a/Documentation/devicetree/bindings/pinctrl/fsl,imx7d-pinctrl.txt b/Documentation/devicetree/bindings/pinctrl/fsl,imx7d-pinctrl.txt
index 8bbf25d..aae069f 100644
--- a/Documentation/devicetree/bindings/pinctrl/fsl,imx7d-pinctrl.txt
+++ b/Documentation/devicetree/bindings/pinctrl/fsl,imx7d-pinctrl.txt
@@ -1,16 +1,42 @@
* Freescale i.MX7 Dual IOMUX Controller
+iMX7D supports two iomuxc controllers, fsl,imx7d-iomuxc controller is similar
+as previous iMX SoC generation and fsl,imx7d-iomuxc-lpsr which provides low
+power state retention capabilities on gpios that are part of iomuxc-lpsr
+(GPIO1_IO7..GPIO1_IO0). While iomuxc-lpsr provides its own set of registers for
+mux and pad control settings, it shares the input select register from main
+iomuxc controller for daisy chain settings, the fsl,input-sel property extends
+fsl,imx-pinctrl driver to support iomuxc-lpsr controller.
+
+iomuxc_lpsr: iomuxc-lpsr@302c0000 {
+ compatible = "fsl,imx7d-iomuxc-lpsr";
+ reg = <0x302c0000 0x10000>;
+ fsl,input-sel = <&iomuxc>;
+};
+
+iomuxc: iomuxc@30330000 {
+ compatible = "fsl,imx7d-iomuxc";
+ reg = <0x30330000 0x10000>;
+};
+
+Pheriparials using pads from iomuxc-lpsr support low state retention power
+state, under LPSR mode GPIO's state of pads are retain.
+
Please refer to fsl,imx-pinctrl.txt in this directory for common binding part
and usage.
Required properties:
-- compatible: "fsl,imx7d-iomuxc"
+- compatible: "fsl,imx7d-iomuxc" for main IOMUXC controller, or
+ "fsl,imx7d-iomuxc-lpsr" for Low Power State Retention IOMUXC controller.
- fsl,pins: each entry consists of 6 integers and represents the mux and config
setting for one pin. The first 5 integers <mux_reg conf_reg input_reg mux_val
input_val> are specified using a PIN_FUNC_ID macro, which can be found in
imx7d-pinfunc.h under device tree source folder. The last integer CONFIG is
the pad setting value like pull-up on this pin. Please refer to i.MX7 Dual
Reference Manual for detailed CONFIG settings.
+- fsl,input-sel: required property for iomuxc-lpsr controller, this property is
+ a phandle for main iomuxc controller which shares the input select register for
+ daisy chain settings.
CONFIG bits definition:
PAD_CTL_PUS_100K_DOWN (0 << 5)
@@ -25,3 +51,38 @@ PAD_CTL_DSE_X1 (0 << 0)
PAD_CTL_DSE_X2 (1 << 0)
PAD_CTL_DSE_X3 (2 << 0)
PAD_CTL_DSE_X4 (3 << 0)
+
+Examples:
+While iomuxc-lpsr is intended to be used by dedicated peripherals to take
+advantages of LPSR power mode, is also possible that an IP to use pads from
+any of the iomux controllers. For example the I2C1 IP can use SCL pad from
+iomuxc-lpsr controller and SDA pad from iomuxc controller as:
+
+i2c1: i2c@30a20000 {
+ pinctrl-names = "default";
+ pinctrl-0 = <&pinctrl_i2c1_1 &pinctrl_i2c1_2>;
+ status = "okay";
+};
+
+iomuxc-lpsr@302c0000 {
+ compatible = "fsl,imx7d-iomuxc-lpsr";
+ reg = <0x302c0000 0x10000>;
+ fsl,input-sel = <&iomuxc>;
+
+ pinctrl_i2c1_1: i2c1grp-1 {
+ fsl,pins = <
+ MX7D_PAD_GPIO1_IO04__I2C1_SCL 0x4000007f
+ >;
+ };
+};
+
+iomuxc@30330000 {
+ compatible = "fsl,imx7d-iomuxc";
+ reg = <0x30330000 0x10000>;
+
+ pinctrl_i2c1_2: i2c1grp-2 {
+ fsl,pins = <
+ MX7D_PAD_I2C1_SCL__I2C1_SCL 0x4000007f
+ >;
+ };
+};
--
2.1.4
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