i2c: core: add generic I2C GPIO recovery

Multiple I2C bus drivers use similar bindings to obtain information needed
for I2C recovery. For example, for platforms using device-tree, the
properties look something like this:

&i2c {
	...
	pinctrl-names = "default", "gpio";
	pinctrl-0 = <&pinctrl_i2c_default>;
	pinctrl-1 = <&pinctrl_i2c_gpio>;
	sda-gpios = <&pio 0 GPIO_ACTIVE_HIGH>;
	scl-gpios = <&pio 1 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
	...
}

For this reason, we can add this common initialization in the core. This
way, other I2C bus drivers will be able to support GPIO recovery just by
providing a pointer to platform's pinctrl and calling i2c_recover_bus()
when SDA is stuck low.

Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
[wsa: inverted one logic for better readability, minor update to kdoc]
Signed-off-by: Wolfram Sang <wsa@kernel.org>

1 files changed, 11 insertions, 0 deletions

diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 8ea9c3f86dba..d387d3786429 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -606,6 +606,14 @@ struct i2c_timings {
  *	may configure padmux here for SDA/SCL line or something else they want.
  * @scl_gpiod: gpiod of the SCL line. Only required for GPIO recovery.
  * @sda_gpiod: gpiod of the SDA line. Only required for GPIO recovery.
+ * @pinctrl: pinctrl used by GPIO recovery to change the state of the I2C pins.
+ *      Optional.
+ * @pins_default: default pinctrl state of SCL/SDA lines, when they are assigned
+ *      to the I2C bus. Optional. Populated internally for GPIO recovery, if
+ *      state with the name PINCTRL_STATE_DEFAULT is found and pinctrl is valid.
+ * @pins_gpio: recovery pinctrl state of SCL/SDA lines, when they are used as
+ *      GPIOs. Optional. Populated internally for GPIO recovery, if this state
+ *      is called "gpio" or "recovery" and pinctrl is valid.
  */
 struct i2c_bus_recovery_info {
 	int (*recover_bus)(struct i2c_adapter *adap);
@@ -622,6 +630,9 @@ struct i2c_bus_recovery_info {
 	/* gpio recovery */
 	struct gpio_desc *scl_gpiod;
 	struct gpio_desc *sda_gpiod;
+	struct pinctrl *pinctrl;
+	struct pinctrl_state *pins_default;
+	struct pinctrl_state *pins_gpio;
 };
 
 int i2c_recover_bus(struct i2c_adapter *adap);