dts/bindings/pinctrl/espressif,esp32-pinctrl.yaml - third_party/github/zephyrproject-rtos/zephyr - Git at Google

 # Copyright (c) 2022 Espressif Systems (Shanghai) Co., Ltd.
 # SPDX-License-Identifier: Apache-2.0

 description: |
     Espressif's Pin controller Node
     Based on pincfg-node.yaml binding.
     Espressif's pin controller is in charge of controlling pin configurations, pin
     functionalities and pin properties as defined by pin states. In its turn, pin
     states are composed of pre-defined pin muxing definitions and user-provided
     pin properties.

     Each Zephyr-based application has its own set of pin muxing/pin configuration
     requirements. The next steps use ESP-WROVER-KIT's I2C_0 to illustrate how one
     could change a node's pin state properties. Though based on a particular board,
     the same steps can be tweaked to address specifics of any other target board.

     Suppose an application running on top of the ESP-WROVER-KIT board, for some
     reason it needs I2C_0's SDA signal to be routed to GPIO_33. When looking at
     that board's original device tree source file (i.e., 'esp_wrover_kit.dts'),
     you'll notice that the I2C_0 node is already assigned to a set of states.
     Below is highlighted the information that most interests us on that file


         #include "esp_wrover_kit-pinctrl.dtsi"

         &i2c0 {
                 pinctrl-0 = <&i2c0_sda_gpio21 &i2c0_scl_gpio22>;
                 pinctrl-names = "default";
         };


     From the above excerpt, the pincrl-0 property is composed of 'i2c0_sda_gpio21'
     and 'i2c0_scl_gpio22' pin states. The naming convention makes it clear that
     I2C_0's SDA signal is, by default, routed to GPIO_21 on the target board. Pin
     states are defined on another file (i.e, 'esp_wrover_kit-pinctrl.dtsi') on
     the same folder of the DTS file. Check below the excerpt describing SDA's
     pin state


         i2c0_sda_gpio21: i2c0_sda_gpio21 {
                 pinmux = <I2C0_SDA_GPIO21>;
                 bias-pull-up;
                 drive-open-drain;
                 output-high;
         };


     Only the 'pinmux' property above is actually required, other properties can
     be chosen if meaningful for the target application and, of course, supported
     by your target hardware. For example, some custom board may have an external
     pull-up resistor soldered to GPIO_21's pin pad, in which case, 'bias-pull-up'
     could be no longer required.

     Back to our fictional application, the previous SDA state definition does not
     meet our expectations, remember, we would like to route I2C_0's SDA signal to
     GPIO_33 and not to GPIO_21. To achieve our goal, we need to update the 'pinmux'
     property accordingly.

     Note that replacing 'I2C0_SDA_GPIO21' by 'I2C0_SDA_GPIO33' is very tempting and
     may even work, however, unless you have checked the hardware documentation first,
     it is not recommended. That's because there are no guarantees that a particular
     IO pin has the capability to route any specific signal.

     The recommendation is to check the pinmux macros definitions available for the
     target SoC in the following URL


     https://github.com/zephyrproject-rtos/hal_espressif/tree/zephyr/include/dt-bindings/pinctrl


     The ESP-WROVER-KIT board is based on the ESP32 SoC, in that case, we search
     through the file 'esp32-pinctrl.h' in the above URL. Luckily for us, there is
     one definition on that file that corresponds to our needs


         #define I2C0_SDA_GPIO33 \
                 ESP32_PINMUX(33, ESP_I2CEXT0_SDA_IN, ESP_I2CEXT0_SDA_OUT)


     Now, we go back to edit 'esp_wrover_kit-pinctrl.dtsi' and create a new pin state
     on that file (or replace/update the one already defined) using the pinmux macro
     definition above, yielding


         i2c0_sda_gpio33: i2c0_sda_gpio33 {
                 pinmux = <I2C0_SDA_GPIO33>;
                 bias-pull-up;
                 drive-open-drain;
                 output-high;
         };


     Finally, update the I2C0 node state information in the device tree source using the
     new (or updated) state


         &ic20 {
                 pinctrl-0 = <&i2c0_sda_gpio33 &i2c0_scl_gpio22>;
                 pinctrl-names = "default";
         };


     With proper adaptations, the same steps above apply when using different
     combinations of boards, SoCs, peripherals and peripheral pins.

     Note: Not all pins are available for a given peripheral, it depends if that
           pin supports a set of properties required by the target peripheral.

           When defining a state, the pin muxing information is constrained to
           the definitions at 'hal_espressif', however, pin properties (like
           bias-push-pull, drive-open-drain, etc) can be freely chosen, given the
           property is meaningful to the peripheral signal and that it is also
           available in the target GPIO.


 compatible: "espressif,esp32-pinctrl"

 include:
     - name: base.yaml
     - name: pincfg-node.yaml
       child-binding:
         property-allowlist:
           - bias-disable
           - bias-pull-down
           - bias-pull-up
           - drive-push-pull
           - drive-open-drain
           - input-enable
           - output-enable
           - output-high
           - output-low

 properties:
     reg:
       required: false

 child-binding:
     description: |
         This binding gives a base representation of the ESP32 pins configuration

     properties:
         pinmux:
           required: true
           type: int
           description: |
             Integer value, represents pin mux settings.
             With:
             - pin: The gpio pin number (0, 1, ..., GPIO_NUM_MAX)
             - sigi: The input signal assigned to a pin, if not available, it gets
               assigned to ESP_NOSIG
             - sigo: The output signal assigned to a pin, if not available, it gets
               assigned to ESP_NOSIG
             To simplify the usage, macro is available to generate "pinmux" field.
             This macro is available here:
               -include/zephyr/dt-bindings/pinctrl/esp-pinctrl-common.h
             Some examples of macro usage:
                GPIO 3 set as UART0's RX pin
             ... {
                      pinmux = <ESP32_PINMUX(3, ESP_U0RXD_IN, ESP_NOSIG)>;
             };
	# Copyright (c) 2022 Espressif Systems (Shanghai) Co., Ltd.
	# SPDX-License-Identifier: Apache-2.0

	description: \|
	Espressif's Pin controller Node
	Based on pincfg-node.yaml binding.
	Espressif's pin controller is in charge of controlling pin configurations, pin
	functionalities and pin properties as defined by pin states. In its turn, pin
	states are composed of pre-defined pin muxing definitions and user-provided
	pin properties.

	Each Zephyr-based application has its own set of pin muxing/pin configuration
	requirements. The next steps use ESP-WROVER-KIT's I2C_0 to illustrate how one
	could change a node's pin state properties. Though based on a particular board,
	the same steps can be tweaked to address specifics of any other target board.

	Suppose an application running on top of the ESP-WROVER-KIT board, for some
	reason it needs I2C_0's SDA signal to be routed to GPIO_33. When looking at
	that board's original device tree source file (i.e., 'esp_wrover_kit.dts'),
	you'll notice that the I2C_0 node is already assigned to a set of states.
	Below is highlighted the information that most interests us on that file


	#include "esp_wrover_kit-pinctrl.dtsi"

	&i2c0 {
	pinctrl-0 = <&i2c0_sda_gpio21 &i2c0_scl_gpio22>;
	pinctrl-names = "default";
	};


	From the above excerpt, the pincrl-0 property is composed of 'i2c0_sda_gpio21'
	and 'i2c0_scl_gpio22' pin states. The naming convention makes it clear that
	I2C_0's SDA signal is, by default, routed to GPIO_21 on the target board. Pin
	states are defined on another file (i.e, 'esp_wrover_kit-pinctrl.dtsi') on
	the same folder of the DTS file. Check below the excerpt describing SDA's
	pin state


	i2c0_sda_gpio21: i2c0_sda_gpio21 {
	pinmux = <I2C0_SDA_GPIO21>;
	bias-pull-up;
	drive-open-drain;
	output-high;
	};


	Only the 'pinmux' property above is actually required, other properties can
	be chosen if meaningful for the target application and, of course, supported
	by your target hardware. For example, some custom board may have an external
	pull-up resistor soldered to GPIO_21's pin pad, in which case, 'bias-pull-up'
	could be no longer required.

	Back to our fictional application, the previous SDA state definition does not
	meet our expectations, remember, we would like to route I2C_0's SDA signal to
	GPIO_33 and not to GPIO_21. To achieve our goal, we need to update the 'pinmux'
	property accordingly.

	Note that replacing 'I2C0_SDA_GPIO21' by 'I2C0_SDA_GPIO33' is very tempting and
	may even work, however, unless you have checked the hardware documentation first,
	it is not recommended. That's because there are no guarantees that a particular
	IO pin has the capability to route any specific signal.

	The recommendation is to check the pinmux macros definitions available for the
	target SoC in the following URL


	https://github.com/zephyrproject-rtos/hal_espressif/tree/zephyr/include/dt-bindings/pinctrl


	The ESP-WROVER-KIT board is based on the ESP32 SoC, in that case, we search
	through the file 'esp32-pinctrl.h' in the above URL. Luckily for us, there is
	one definition on that file that corresponds to our needs


	#define I2C0_SDA_GPIO33 \
	ESP32_PINMUX(33, ESP_I2CEXT0_SDA_IN, ESP_I2CEXT0_SDA_OUT)


	Now, we go back to edit 'esp_wrover_kit-pinctrl.dtsi' and create a new pin state
	on that file (or replace/update the one already defined) using the pinmux macro
	definition above, yielding


	i2c0_sda_gpio33: i2c0_sda_gpio33 {
	pinmux = <I2C0_SDA_GPIO33>;
	bias-pull-up;
	drive-open-drain;
	output-high;
	};


	Finally, update the I2C0 node state information in the device tree source using the
	new (or updated) state


	&ic20 {
	pinctrl-0 = <&i2c0_sda_gpio33 &i2c0_scl_gpio22>;
	pinctrl-names = "default";
	};


	With proper adaptations, the same steps above apply when using different
	combinations of boards, SoCs, peripherals and peripheral pins.

	Note: Not all pins are available for a given peripheral, it depends if that
	pin supports a set of properties required by the target peripheral.

	When defining a state, the pin muxing information is constrained to
	the definitions at 'hal_espressif', however, pin properties (like
	bias-push-pull, drive-open-drain, etc) can be freely chosen, given the
	property is meaningful to the peripheral signal and that it is also
	available in the target GPIO.


	compatible: "espressif,esp32-pinctrl"

	include:
	- name: base.yaml
	- name: pincfg-node.yaml
	child-binding:
	property-allowlist:
	- bias-disable
	- bias-pull-down
	- bias-pull-up
	- drive-push-pull
	- drive-open-drain
	- input-enable
	- output-enable
	- output-high
	- output-low

	properties:
	reg:
	required: false

	child-binding:
	description: \|
	This binding gives a base representation of the ESP32 pins configuration

	properties:
	pinmux:
	required: true
	type: int
	description: \|
	Integer value, represents pin mux settings.
	With:
	- pin: The gpio pin number (0, 1, ..., GPIO_NUM_MAX)
	- sigi: The input signal assigned to a pin, if not available, it gets
	assigned to ESP_NOSIG
	- sigo: The output signal assigned to a pin, if not available, it gets
	assigned to ESP_NOSIG
	To simplify the usage, macro is available to generate "pinmux" field.
	This macro is available here:
	-include/zephyr/dt-bindings/pinctrl/esp-pinctrl-common.h
	Some examples of macro usage:
	GPIO 3 set as UART0's RX pin
	... {
	pinmux = <ESP32_PINMUX(3, ESP_U0RXD_IN, ESP_NOSIG)>;
	};