drivers: can: transceiver: termination gpio

The functionality for termination gpio is used on
some boards like ST's b-g431b-esc1 motor controller board.
This feature is also supported by SocketCAN in linux.

Signed-off-by: Alexander Kozhinov <ak.alexander.kozhinov@gmail.com>

drivers/can/transceiver/can_transceiver_gpio.c

@@ -21,13 +21,20 @@ LOG_MODULE_REGISTER(can_transceiver_gpio, CONFIG_CAN_LOG_LEVEL);
 #define INST_HAS_STANDBY_GPIOS_OR(inst) DT_INST_NODE_HAS_PROP(inst, standby_gpios) ||
 #define ANY_INST_HAS_STANDBY_GPIOS DT_INST_FOREACH_STATUS_OKAY(INST_HAS_STANDBY_GPIOS_OR) 0
 
+/* Does any devicetree instance have a term-gpios property? */
+#define INST_HAS_TERM_GPIOS_OR(inst) DT_INST_NODE_HAS_PROP(inst, termination_gpios) ||
+#define ANY_INST_HAS_TERM_GPIOS DT_INST_FOREACH_STATUS_OKAY(INST_HAS_TERM_GPIOS_OR) 0
+
 struct can_transceiver_gpio_config {
 #if ANY_INST_HAS_ENABLE_GPIOS
 	struct gpio_dt_spec enable_gpio;
 #endif /* ANY_INST_HAS_ENABLE_GPIOS */
 #if ANY_INST_HAS_STANDBY_GPIOS
 	struct gpio_dt_spec standby_gpio;
 #endif /* ANY_INST_HAS_STANDBY_GPIOS */
+#if ANY_INST_HAS_TERM_GPIOS
+	struct gpio_dt_spec termination_gpio;
+#endif /* ANY_INST_HAS_TERM_GPIOS */
 };
 
 static int can_transceiver_gpio_set_state(const struct device *dev, bool enabled)
@@ -110,9 +117,37 @@ static int can_transceiver_gpio_init(const struct device *dev)
 	return 0;
 }
 
+static int can_transceiver_gpio_set_termination(const struct device *dev,
+												bool enabled)
+{
+#if ANY_INST_HAS_TERM_GPIOS
+	if (config->termination_gpio.port != NULL) {
+		err = gpio_pin_set_dt(&config->termination_gpio, enabled ? 0 : 1);
+		if (err != 0) {
+			LOG_ERR("failed to set termination GPIO pin (err %d)", err);
+			return -EIO;
+		}
+	}
+#endif /* ANY_INST_HAS_TERM_GPIOS */
+
+	return 0;
+}
+
+static int can_transceiver_gpio_termination_enable(const struct device *dev)
+{
+	return can_transceiver_gpio_set_termination(dev, true);
+}
+
+static int can_transceiver_gpio_termination_disable(const struct device *dev)
+{
+	return can_transceiver_gpio_set_termination(dev, false);
+}
+
 static DEVICE_API(can_transceiver, can_transceiver_gpio_driver_api) = {
 	.enable = can_transceiver_gpio_enable,
 	.disable = can_transceiver_gpio_disable,
+	.termination_enable = can_transceiver_gpio_termination_enable,
+	.termination_disable = can_transceiver_gpio_termination_disable,
 };
 
 #define CAN_TRANSCEIVER_GPIO_COND(inst, name)				\
@@ -121,13 +156,16 @@ static DEVICE_API(can_transceiver, can_transceiver_gpio_driver_api) = {
 
 #define CAN_TRANSCEIVER_GPIO_INIT(inst)					\
 	BUILD_ASSERT(DT_INST_NODE_HAS_PROP(inst, enable_gpios) ||	\
-		     DT_INST_NODE_HAS_PROP(inst, standby_gpios),	\
+		     DT_INST_NODE_HAS_PROP(inst, standby_gpios),		\
+		     DT_INST_NODE_HAS_PROP(inst, termination_gpios),	\
 		     "Missing GPIO property on "			\
 		     DT_NODE_FULL_NAME(DT_DRV_INST(inst)));		\
 									\
 	static const struct can_transceiver_gpio_config	can_transceiver_gpio_config_##inst = { \
 		CAN_TRANSCEIVER_GPIO_COND(inst, enable)			\
 		CAN_TRANSCEIVER_GPIO_COND(inst, standby)		\
+		CAN_TRANSCEIVER_GPIO_COND(inst, termination_enable)		\
+		CAN_TRANSCEIVER_GPIO_COND(inst, termination_disable)	\
 	};								\
 									\
 	DEVICE_DT_INST_DEFINE(inst, &can_transceiver_gpio_init,		\

dts/bindings/phy/can-transceiver-gpio.yaml

@@ -21,3 +21,9 @@ properties:
       GPIO to use to put the CAN transceiver into standby. This GPIO is driven
       inactive when the CAN transceiver is enabled and active when the CAN
       transceiver is disabled.
+
+  termination-gpios:
+    type: phandle-array
+    description: |
+      GPIO to use to enable/disable the CAN transceiver termination resistor.
+      This GPIO will be not changed during CAN transceiver initialzation phase.

include/zephyr/drivers/can/transceiver.h

@@ -41,9 +41,23 @@ typedef int (*can_transceiver_enable_t)(const struct device *dev, can_mode_t mod
  */
 typedef int (*can_transceiver_disable_t)(const struct device *dev);
 
+/**
+ * @brief Callback API upon enabling CAN transceiver termination
+ * See @a can_transceiver_termination_enable() for argument description
+ */
+typedef int (*can_transceiver_termination_enable_t)(const struct device *dev);
+
+/**
+ * @brief Callback API upon disabling CAN transceiver termination
+ * See @a can_transceiver_termination_disable() for argument description
+ */
+typedef int (*can_transceiver_termination_disable_t)(const struct device *dev);
+
 __subsystem struct can_transceiver_driver_api {
 	can_transceiver_enable_t enable;
 	can_transceiver_disable_t disable;
+	can_transceiver_termination_enable_t termination_enable;
+	can_transceiver_termination_disable_t termination_disable;
 };
 
 /** @endcond */
@@ -87,6 +101,40 @@ static inline int can_transceiver_disable(const struct device *dev)
 	return DEVICE_API_GET(can_transceiver, dev)->disable(dev);
 }
 
+/**
+ * @brief Enable CAN transceiver termination
+ *
+ * Enable CAN transceiver termination by puttig 120ohm between CAN_H and CAN_L.
+ *
+ * @note The CAN transceiver is controlled by the CAN controller driver and
+ *       should not normally be controlled by the application.
+ *
+ * @param dev Pointer to the device structure for the driver instance.
+ * @retval 0 If successful.
+ * @retval -EIO General input/output error, failed to enable device.
+ */
+static inline int can_transceiver_termination_enable(const struct device *dev)
+{
+	return DEVICE_API_GET(can_transceiver, dev)->termination_enable(dev);
+}
+
+/**
+ * @brief Disable CAN transceiver termination
+ *
+ * Disable CAN transceiver termination by puttig 120ohm between CAN_H and CAN_L.
+ *
+ * @note The CAN transceiver is controlled by the CAN controller driver and
+ *       should not normally be controlled by the application.
+ *
+ * @param dev Pointer to the device structure for the driver instance.
+ * @retval 0 If successful.
+ * @retval -EIO General input/output error, failed to enable device.
+ */
+static inline int can_transceiver_termination_disable(const struct device *dev)
+{
+	return DEVICE_API_GET(can_transceiver, dev)->termination_disable(dev);
+}
+
 /**
  * @}
  */