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-rw-r--r--Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt48
1 files changed, 43 insertions, 5 deletions
diff --git a/Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt b/Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
index bf3f7b014724..71a3c134af1b 100644
--- a/Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
+++ b/Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
@@ -162,8 +162,8 @@ state_2_node_a {
pins = "mfio29", "mfio30";
};
-Optionally an altenative binding can be used if more suitable depending on the
-pin controller hardware. For hardaware where there is a large number of identical
+Optionally an alternative binding can be used if more suitable depending on the
+pin controller hardware. For hardware where there is a large number of identical
pin controller instances, naming each pin and function can easily become
unmaintainable. This is especially the case if the same controller is used for
different pins and functions depending on the SoC revision and packaging.
@@ -198,6 +198,28 @@ registers, and must not be a virtual index of pin instances. The reason for
this is to avoid mapping of the index in the dts files and the pin controller
driver as it can change.
+For hardware where pin multiplexing configurations have to be specified for
+each single pin the number of required sub-nodes containing "pin" and
+"function" properties can quickly escalate and become hard to write and
+maintain.
+
+For cases like this, the pin controller driver may use the pinmux helper
+property, where the pin identifier is packed with mux configuration settings
+in a single integer.
+
+The pinmux property accepts an array of integers, each of them describing
+a single pin multiplexing configuration.
+
+pincontroller {
+ state_0_node_a {
+ pinmux = <PIN_ID_AND_MUX>, <PIN_ID_AND_MUX>, ...;
+ };
+};
+
+Each individual pin controller driver bindings documentation shall specify
+how those values (pin IDs and pin multiplexing configuration) are defined and
+assembled together.
+
== Generic pin configuration node content ==
Many data items that are represented in a pin configuration node are common
@@ -210,18 +232,22 @@ structure of the DT nodes that contain these properties.
Supported generic properties are:
pins - the list of pins that properties in the node
- apply to (either this or "group" has to be
+ apply to (either this, "group" or "pinmux" has to be
specified)
group - the group to apply the properties to, if the driver
supports configuration of whole groups rather than
- individual pins (either this or "pins" has to be
- specified)
+ individual pins (either this, "pins" or "pinmux" has
+ to be specified)
+pinmux - the list of numeric pin ids and their mux settings
+ that properties in the node apply to (either this,
+ "pins" or "groups" have to be specified)
bias-disable - disable any pin bias
bias-high-impedance - high impedance mode ("third-state", "floating")
bias-bus-hold - latch weakly
bias-pull-up - pull up the pin
bias-pull-down - pull down the pin
bias-pull-pin-default - use pin-default pull state
+bi-directional - pin supports simultaneous input/output operations
drive-push-pull - drive actively high and low
drive-open-drain - drive with open drain
drive-open-source - drive with open source
@@ -234,6 +260,7 @@ input-debounce - debounce mode with debound time X
power-source - select between different power supplies
low-power-enable - enable low power mode
low-power-disable - disable low power mode
+output-enable - enable output on pin regardless of output value
output-low - set the pin to output mode with low level
output-high - set the pin to output mode with high level
slew-rate - set the slew rate
@@ -258,6 +285,12 @@ state_2_node_a {
bias-pull-up;
};
};
+state_3_node_a {
+ mux {
+ pinmux = <GPIOx_PINm_MUXn>, <GPIOx_PINj_MUXk)>;
+ input-enable;
+ };
+};
Some of the generic properties take arguments. For those that do, the
arguments are described below.
@@ -266,6 +299,11 @@ arguments are described below.
binding for the hardware defines:
- Whether the entries are integers or strings, and their meaning.
+- pinmux takes a list of pin IDs and mux settings as required argument. The
+ specific bindings for the hardware defines:
+ - How pin IDs and mux settings are defined and assembled together in a single
+ integer.
+
- bias-pull-up, -down and -pin-default take as optional argument on hardware
supporting it the pull strength in Ohm. bias-disable will disable the pull.