drivers: pinctrl: rp2040: oe-override option

This change adds the device tree property for specifying oe-override
(output-enable override behavior), as well as defines for possible values
of the property.

RP2040 GPIOs can be configured to automatically invert the output-enable
signal from the selected peripheral function. This is useful for tasks like
writing efficient PIO code, such as in the i2c example in the rp2040
datasheet.


Signed-off-by: Yiding Jia <yiding.jia@gmail.com>

drivers/pinctrl/pinctrl_rpi_pico.c

@@ -19,6 +19,7 @@ static void pinctrl_configure_pin(const pinctrl_soc_pin_t *pin)
 				GPIO_SLEW_RATE_FAST : GPIO_SLEW_RATE_SLOW));
 	gpio_set_input_hysteresis_enabled(pin->pin_num, pin->schmitt_enable);
 	gpio_set_input_enabled(pin->pin_num, pin->input_enable);
+	gpio_set_oeover(pin->pin_num, pin->oe_override);
 }
 
 int pinctrl_configure_pins(const pinctrl_soc_pin_t *pins, uint8_t pin_cnt,

dts/bindings/pinctrl/raspberrypi,pico-pinctrl.yaml

@@ -121,3 +121,22 @@ child-binding:
         description: |
           The slew rate of a pin. 0 corresponds to slow, and 1 corresponds to fast.
           The default value is 0 (slow), as this is the power on reset value.
+      raspberrypi,oe-override:
+        type: int
+        enum:
+          - 0
+          - 1
+          - 2
+          - 3
+        default: 0
+        description: |
+          Override output-enable for a pin.
+
+          - 0 (RP2_GPIO_OVERRIDE_NORMAL) - drive output enable from selected
+              peripheral signal.
+          - 1 (RP2_GPIO_OVERRIDE_INVERT) - drive output enable from inverse of
+              selected peripheral signal.
+          - 2 (RP2_GPIO_OVERRIDE_LOW) - disable output.
+          - 3 (RP2_GPIO_OVERRIDE_HIGH) - enable output.
+
+          The default value is 0, as this is the power on reset value.

include/zephyr/dt-bindings/pinctrl/rpi-pico-rp2040-pinctrl.h

@@ -25,6 +25,11 @@
 #define RP2_PIN_NUM_POS 4
 #define RP2_PIN_NUM_MASK 0x1f
 
+#define RP2_GPIO_OVERRIDE_NORMAL 0
+#define RP2_GPIO_OVERRIDE_INVERT 1
+#define RP2_GPIO_OVERRIDE_LOW 2
+#define RP2_GPIO_OVERRIDE_HIGH 3
+
 #define RP2040_PINMUX(pin_num, alt_func) (pin_num << RP2_PIN_NUM_POS |	\
 					alt_func << RP2_ALT_FUNC_POS)
 

soc/raspberrypi/rp2xxx/pinctrl_soc.h

@@ -29,6 +29,8 @@ struct rpi_pinctrl_soc_pin {
 	uint32_t input_enable : 1;
 	/** Enable the internal schmitt trigger */
 	uint32_t schmitt_enable : 1;
+	/** Output-enable override */
+	uint32_t oe_override : 2;
 };
 
 typedef struct rpi_pinctrl_soc_pin pinctrl_soc_pin_t;
@@ -50,6 +52,7 @@ typedef struct rpi_pinctrl_soc_pin pinctrl_soc_pin_t;
 		DT_PROP(node_id, bias_pull_down),				\
 		DT_PROP(node_id, input_enable),					\
 		DT_PROP(node_id, input_schmitt_enable),				\
+		DT_PROP(node_id, raspberrypi_oe_override),				\
 	},
 
 /**