drivers: can: remove CAN_BUS_UNKNOWN CAN controller state

The CAN_BUS_UNKNOWN CAN controller state is only used to indicate that
the current CAN controller state could not be read.

Remove it and change the signature of the can_get_state() API function
to return an integer indicating success or failure.

Signed-off-by: Henrik Brix Andersen <hebad@vestas.com>

drivers/can/can_handlers.c

@@ -81,21 +81,24 @@ static inline void z_vrfy_can_remove_rx_filter(const struct device *dev, int fil
 #include <syscalls/can_remove_rx_filter_mrsh.c>
 
 static inline
-enum can_state z_vrfy_can_get_state(const struct device *dev,
+int z_vrfy_can_get_state(const struct device *dev, enum can_state *state,
 			 struct can_bus_err_cnt *err_cnt)
 {
 
 	Z_OOPS(Z_SYSCALL_OBJ(dev, K_OBJ_DRIVER_CAN));
 
-	if (err_cnt) {
+	if (state != NULL) {
-		Z_OOPS(Z_SYSCALL_MEMORY_WRITE(err_cnt, sizeof(err_cnt)));
+		Z_OOPS(Z_SYSCALL_MEMORY_WRITE(state, sizeof(enum can_state)));
 	}
 
-	return z_impl_can_get_state(dev, err_cnt);
+	if (err_cnt != NULL) {
+		Z_OOPS(Z_SYSCALL_MEMORY_WRITE(err_cnt, sizeof(struct can_bus_err_cnt)));
+	}
+
+	return z_impl_can_get_state(dev, state, err_cnt);
 }
 #include <syscalls/can_get_state_mrsh.c>
 
-
 #ifndef CONFIG_CAN_AUTO_BUS_OFF_RECOVERY
 static inline int z_vrfy_can_recover(const struct device *dev,
 				     k_timeout_t timeout)

drivers/can/can_loopback.c

@@ -212,17 +212,21 @@ int can_loopback_set_timing(const struct device *dev,
 	return 0;
 }
 
-static enum can_state can_loopback_get_state(const struct device *dev,
+static int can_loopback_get_state(const struct device *dev, enum can_state *state,
 				  struct can_bus_err_cnt *err_cnt)
 {
 	ARG_UNUSED(dev);
 
+	if (state != NULL) {
+		*state = CAN_ERROR_ACTIVE;
+	}
+
 	if (err_cnt) {
 		err_cnt->tx_err_cnt = 0;
 		err_cnt->rx_err_cnt = 0;
 	}
 
-	return CAN_ERROR_ACTIVE;
+	return 0;
 }
 
 #ifndef CONFIG_CAN_AUTO_BUS_OFF_RECOVERY

drivers/can/can_mcan.c

@@ -451,7 +451,7 @@ static void can_mcan_state_change_handler(const struct can_mcan_config *cfg,
 	const can_state_change_callback_t cb = data->state_change_cb;
 	void *cb_data = data->state_change_cb_data;
 
-	state = can_mcan_get_state(cfg, &err_cnt);
+	(void)can_mcan_get_state(cfg, &state, &err_cnt);
 
 	if (cb != NULL) {
 		cb(state, err_cnt, cb_data);
@@ -642,30 +642,32 @@ void can_mcan_line_1_isr(const struct can_mcan_config *cfg,
 			    CAN_MCAN_IR_RF0L | CAN_MCAN_IR_RF1L));
 }
 
-enum can_state can_mcan_get_state(const struct can_mcan_config *cfg,
+int can_mcan_get_state(const struct can_mcan_config *cfg, enum can_state *state,
 		       struct can_bus_err_cnt *err_cnt)
 {
 	struct can_mcan_reg *can = cfg->can;
 
+	if (state != NULL) {
+		if (can->psr & CAN_MCAN_PSR_BO) {
+			*state = CAN_BUS_OFF;
+		} else if (can->psr & CAN_MCAN_PSR_EP) {
+			*state = CAN_ERROR_PASSIVE;
+		} else if (can->psr & CAN_MCAN_PSR_EW) {
+			*state = CAN_ERROR_WARNING;
+		} else {
+			*state = CAN_ERROR_ACTIVE;
+		}
+	}
+
+	if (err_cnt != NULL) {
 		err_cnt->rx_err_cnt = (can->ecr & CAN_MCAN_ECR_TEC_MSK) <<
 				      CAN_MCAN_ECR_TEC_POS;
 
 		err_cnt->tx_err_cnt = (can->ecr & CAN_MCAN_ECR_REC_MSK) <<
 				      CAN_MCAN_ECR_REC_POS;
-
-	if (can->psr & CAN_MCAN_PSR_BO) {
-		return CAN_BUS_OFF;
 	}
 
-	if (can->psr & CAN_MCAN_PSR_EP) {
+	return 0;
-		return CAN_ERROR_PASSIVE;
-	}
-
-	if (can->psr & CAN_MCAN_PSR_EW) {
-		return CAN_ERROR_WARNING;
-	}
-
-	return CAN_ERROR_ACTIVE;
 }
 
 #ifndef CONFIG_CAN_AUTO_BUS_OFF_RECOVERY

drivers/can/can_mcan.h

@@ -238,7 +238,7 @@ int can_mcan_add_rx_filter(struct can_mcan_data *data,
 void can_mcan_remove_rx_filter(struct can_mcan_data *data,
 			       struct can_mcan_msg_sram *msg_ram, int filter_id);
 
-enum can_state can_mcan_get_state(const struct can_mcan_config *cfg,
+int can_mcan_get_state(const struct can_mcan_config *cfg, enum can_state *state,
 		       struct can_bus_err_cnt *err_cnt);
 
 #endif /* ZEPHYR_DRIVERS_CAN_MCAN_H_ */

drivers/can/can_mcp2515.c

@@ -649,7 +649,7 @@ static void mcp2515_tx_done(const struct device *dev, uint8_t tx_idx)
 	k_sem_give(&dev_data->tx_sem);
 }
 
-static enum can_state mcp2515_get_state(const struct device *dev,
+static int mcp2515_get_state(const struct device *dev, enum can_state *state,
 			     struct can_bus_err_cnt *err_cnt)
 {
 	uint8_t eflg;
@@ -659,34 +659,34 @@ static enum can_state mcp2515_get_state(const struct device *dev,
 	ret = mcp2515_cmd_read_reg(dev, MCP2515_ADDR_EFLG, &eflg, sizeof(eflg));
 	if (ret < 0) {
 		LOG_ERR("Failed to read error register [%d]", ret);
-		return CAN_BUS_UNKNOWN;
+		return -EIO;
 	}
 
-	if (err_cnt) {
+	if (state != NULL) {
+		if (eflg & MCP2515_EFLG_TXBO) {
+			*state = CAN_BUS_OFF;
+		} else if ((eflg & MCP2515_EFLG_RXEP) || (eflg & MCP2515_EFLG_TXEP)) {
+			*state = CAN_ERROR_PASSIVE;
+		} else if (eflg & MCP2515_EFLG_EWARN) {
+			*state = CAN_ERROR_WARNING;
+		} else {
+			*state = CAN_ERROR_ACTIVE;
+		}
+	}
+
+	if (err_cnt != NULL) {
 		ret = mcp2515_cmd_read_reg(dev, MCP2515_ADDR_TEC, err_cnt_buf,
 					   sizeof(err_cnt_buf));
 		if (ret < 0) {
 			LOG_ERR("Failed to read error counters [%d]", ret);
-			return CAN_BUS_UNKNOWN;
+			return -EIO;
 		}
 
 		err_cnt->tx_err_cnt = err_cnt_buf[0];
 		err_cnt->rx_err_cnt = err_cnt_buf[1];
 	}
 
-	if (eflg & MCP2515_EFLG_TXBO) {
+	return 0;
-		return CAN_BUS_OFF;
-	}
-
-	if ((eflg & MCP2515_EFLG_RXEP) || (eflg & MCP2515_EFLG_TXEP)) {
-		return CAN_ERROR_PASSIVE;
-	}
-
-	if (eflg & MCP2515_EFLG_EWARN) {
-		return CAN_ERROR_WARNING;
-	}
-
-	return CAN_ERROR_ACTIVE;
 }
 
 static void mcp2515_handle_errors(const struct device *dev)
@@ -696,8 +696,13 @@ static void mcp2515_handle_errors(const struct device *dev)
 	void *state_change_cb_data = dev_data->state_change_cb_data;
 	enum can_state state;
 	struct can_bus_err_cnt err_cnt;
+	int err;
 
-	state = mcp2515_get_state(dev, state_change_cb ? &err_cnt : NULL);
+	err = mcp2515_get_state(dev, &state, state_change_cb ? &err_cnt : NULL);
+	if (err != 0) {
+		LOG_ERR("Failed to get CAN controller state [%d]", err);
+		return;
+	}
 
 	if (state_change_cb && dev_data->old_state != state) {
 		dev_data->old_state = state;

drivers/can/can_mcux_flexcan.c

@@ -316,32 +316,33 @@ static int mcux_get_tx_alloc(struct mcux_flexcan_data *data)
 	return alloc >= MCUX_FLEXCAN_MAX_TX ? -1 : alloc;
 }
 
-static enum can_state mcux_flexcan_get_state(const struct device *dev,
+static int mcux_flexcan_get_state(const struct device *dev, enum can_state *state,
 				  struct can_bus_err_cnt *err_cnt)
 {
 	const struct mcux_flexcan_config *config = dev->config;
 	uint64_t status_flags;
 
+	if (state != NULL) {
+		status_flags = FLEXCAN_GetStatusFlags(config->base);
+
+		if ((status_flags & CAN_ESR1_FLTCONF(2)) != 0U) {
+			*state = CAN_BUS_OFF;
+		} else if ((status_flags & CAN_ESR1_FLTCONF(1)) != 0U) {
+			*state = CAN_ERROR_PASSIVE;
+		} else if ((status_flags &
+			(kFLEXCAN_TxErrorWarningFlag | kFLEXCAN_RxErrorWarningFlag)) != 0) {
+			*state = CAN_ERROR_WARNING;
+		} else {
+			*state = CAN_ERROR_ACTIVE;
+		}
+	}
+
 	if (err_cnt != NULL) {
 		FLEXCAN_GetBusErrCount(config->base, &err_cnt->tx_err_cnt,
 				       &err_cnt->rx_err_cnt);
 	}
 
-	status_flags = FLEXCAN_GetStatusFlags(config->base);
+	return 0;
-
-	if ((status_flags & CAN_ESR1_FLTCONF(2)) != 0U) {
-		return CAN_BUS_OFF;
-	}
-
-	if ((status_flags & CAN_ESR1_FLTCONF(1)) != 0U) {
-		return CAN_ERROR_PASSIVE;
-	}
-
-	if ((status_flags & (kFLEXCAN_TxErrorWarningFlag | kFLEXCAN_RxErrorWarningFlag)) != 0) {
-		return CAN_ERROR_WARNING;
-	}
-
-	return CAN_ERROR_ACTIVE;
 }
 
 static int mcux_flexcan_send(const struct device *dev,
@@ -352,6 +353,7 @@ static int mcux_flexcan_send(const struct device *dev,
 	const struct mcux_flexcan_config *config = dev->config;
 	struct mcux_flexcan_data *data = dev->data;
 	flexcan_mb_transfer_t xfer;
+	enum can_state state;
 	status_t status;
 	int alloc;
 
@@ -360,7 +362,8 @@ static int mcux_flexcan_send(const struct device *dev,
 		return -EINVAL;
 	}
 
-	if (mcux_flexcan_get_state(dev, NULL) == CAN_BUS_OFF) {
+	(void)mcux_flexcan_get_state(dev, &state, NULL);
+	if (state == CAN_BUS_OFF) {
 		LOG_DBG("Transmit failed, bus-off");
 		return -ENETDOWN;
 	}
@@ -470,10 +473,12 @@ static void mcux_flexcan_set_state_change_callback(const struct device *dev,
 int mcux_flexcan_recover(const struct device *dev, k_timeout_t timeout)
 {
 	const struct mcux_flexcan_config *config = dev->config;
-	int ret = 0;
+	enum can_state state;
 	uint64_t start_time;
+	int ret = 0;
 
-	if (mcux_flexcan_get_state(dev, NULL) != CAN_BUS_OFF) {
+	(void)mcux_flexcan_get_state(dev, &state, NULL);
+	if (state != CAN_BUS_OFF) {
 		return 0;
 	}
 
@@ -481,11 +486,15 @@ int mcux_flexcan_recover(const struct device *dev, k_timeout_t timeout)
 	config->base->CTRL1 &= ~CAN_CTRL1_BOFFREC_MASK;
 
 	if (!K_TIMEOUT_EQ(timeout, K_NO_WAIT)) {
-		while (mcux_flexcan_get_state(dev, NULL) == CAN_BUS_OFF) {
+		(void)mcux_flexcan_get_state(dev, &state, NULL);
+
+		while (state == CAN_BUS_OFF) {
 			if (!K_TIMEOUT_EQ(timeout, K_FOREVER) &&
 			    k_uptime_ticks() - start_time >= timeout.ticks) {
 				ret = -EAGAIN;
 			}
+
+			(void)mcux_flexcan_get_state(dev, &state, NULL);
 		}
 	}
 
@@ -556,7 +565,7 @@ static inline void mcux_flexcan_transfer_error_status(const struct device *dev,
 		LOG_DBG("RX CRC error (error 0x%016llx)", error);
 	}
 
-	state = mcux_flexcan_get_state(dev, &err_cnt);
+	(void)mcux_flexcan_get_state(dev, &state, &err_cnt);
 	if (data->state != state) {
 		data->state = state;
 
@@ -745,7 +754,8 @@ static int mcux_flexcan_init(const struct device *dev)
 #ifndef CONFIG_CAN_AUTO_BUS_OFF_RECOVERY
 	config->base->CTRL1 |= CAN_CTRL1_BOFFREC_MASK;
 #endif /* CONFIG_CAN_AUTO_BUS_OFF_RECOVERY */
-	data->state = mcux_flexcan_get_state(dev, NULL);
+
+	(void)mcux_flexcan_get_state(dev, &data->state, NULL);
 
 	return 0;
 }

drivers/can/can_mcux_mcan.c

@@ -72,12 +72,12 @@ static void mcux_mcan_remove_rx_filter(const struct device *dev, int filter_id)
 	can_mcan_remove_rx_filter(&data->mcan, &data->msg_ram, filter_id);
 }
 
-static enum can_state mcux_mcan_get_state(const struct device *dev,
+static int mcux_mcan_get_state(const struct device *dev, enum can_state *state,
 			       struct can_bus_err_cnt *err_cnt)
 {
 	const struct mcux_mcan_config *config = dev->config;
 
-	return can_mcan_get_state(&config->mcan, err_cnt);
+	return can_mcan_get_state(&config->mcan, state, err_cnt);
 }
 
 static void mcux_mcan_set_state_change_callback(const struct device *dev,

drivers/can/can_rcar.c

@@ -671,16 +671,21 @@ static void can_rcar_set_state_change_callback(const struct device *dev,
 	data->state_change_cb_data = user_data;
 }
 
-static enum can_state can_rcar_get_state(const struct device *dev,
+static int can_rcar_get_state(const struct device *dev, enum can_state *state,
 			      struct can_bus_err_cnt *err_cnt)
 {
 	const struct can_rcar_cfg *config = DEV_CAN_CFG(dev);
 	struct can_rcar_data *data = DEV_CAN_DATA(dev);
 
+	if (state != NULL) {
+		*state = data->state;
+	}
+
 	if (err_cnt != NULL) {
 		can_rcar_get_error_count(config, err_cnt);
 	}
-	return data->state;
+
+	return 0;
 }
 
 #ifndef CONFIG_CAN_AUTO_BUS_OFF_RECOVERY

drivers/can/can_sam.c

@@ -71,12 +71,13 @@ static int can_sam_init(const struct device *dev)
 	return ret;
 }
 
-static enum can_state can_sam_get_state(const struct device *dev, struct can_bus_err_cnt *err_cnt)
+static int can_sam_get_state(const struct device *dev, enum can_state *state,
+			     struct can_bus_err_cnt *err_cnt)
 {
 	const struct can_sam_config *cfg = dev->config;
 	const struct can_mcan_config *mcan_cfg = &cfg->mcan_cfg;
 
-	return can_mcan_get_state(mcan_cfg, err_cnt);
+	return can_mcan_get_state(mcan_cfg, state, err_cnt);
 }
 
 static int can_sam_send(const struct device *dev, const struct zcan_frame *frame,

drivers/can/can_stm32.c

@@ -551,33 +551,32 @@ static void can_stm32_set_state_change_callback(const struct device *dev,
 	}
 }
 
-static enum can_state can_stm32_get_state(const struct device *dev,
+static int can_stm32_get_state(const struct device *dev, enum can_state *state,
 			       struct can_bus_err_cnt *err_cnt)
 {
 	const struct can_stm32_config *cfg = dev->config;
 	CAN_TypeDef *can = cfg->can;
 
-	if (err_cnt) {
+	if (state != NULL) {
+		if (can->ESR & CAN_ESR_BOFF) {
+			*state = CAN_BUS_OFF;
+		} else if (can->ESR & CAN_ESR_EPVF) {
+			*state = CAN_ERROR_PASSIVE;
+		} else if (can->ESR & CAN_ESR_EWGF) {
+			*state = CAN_ERROR_WARNING;
+		} else {
+			*state = CAN_ERROR_ACTIVE;
+		}
+	}
+
+	if (err_cnt != NULL) {
 		err_cnt->tx_err_cnt =
 			((can->ESR & CAN_ESR_TEC) >> CAN_ESR_TEC_Pos);
 		err_cnt->rx_err_cnt =
 			((can->ESR & CAN_ESR_REC) >> CAN_ESR_REC_Pos);
 	}
 
-	if (can->ESR & CAN_ESR_BOFF) {
+	return 0;
-		return CAN_BUS_OFF;
-	}
-
-	if (can->ESR & CAN_ESR_EPVF) {
-		return CAN_ERROR_PASSIVE;
-	}
-
-	if (can->ESR & CAN_ESR_EWGF) {
-		return CAN_ERROR_WARNING;
-	}
-
-	return CAN_ERROR_ACTIVE;
-
 }
 
 #ifndef CONFIG_CAN_AUTO_BUS_OFF_RECOVERY

drivers/can/can_stm32fd.c

@@ -90,13 +90,13 @@ static int can_stm32fd_init(const struct device *dev)
 	return ret;
 }
 
-static enum can_state can_stm32fd_get_state(const struct device *dev,
+static int can_stm32fd_get_state(const struct device *dev, enum can_state *state,
 				 struct can_bus_err_cnt *err_cnt)
 {
 	const struct can_stm32fd_config *cfg = dev->config;
 	const struct can_mcan_config *mcan_cfg = &cfg->mcan_cfg;
 
-	return can_mcan_get_state(mcan_cfg, err_cnt);
+	return can_mcan_get_state(mcan_cfg, state, err_cnt);
 }
 
 static int can_stm32fd_send(const struct device *dev, const struct zcan_frame *frame,

drivers/can/can_stm32h7.c

@@ -120,12 +120,12 @@ static int can_stm32h7_init(const struct device *dev)
 	return 0;
 }
 
-static enum can_state can_stm32h7_get_state(const struct device *dev,
+static int can_stm32h7_get_state(const struct device *dev, enum can_state *state,
 				 struct can_bus_err_cnt *err_cnt)
 {
 	const struct can_stm32h7_config *cfg = dev->config;
 
-	return can_mcan_get_state(&cfg->mcan_cfg, err_cnt);
+	return can_mcan_get_state(&cfg->mcan_cfg, state, err_cnt);
 }
 
 static int can_stm32h7_send(const struct device *dev,

include/drivers/can.h

@@ -104,8 +104,6 @@ enum can_state {
 	CAN_ERROR_PASSIVE,
 	/** Bus-off state (RX/TX error count >= 256). */
 	CAN_BUS_OFF,
-	/** Bus state unknown. */
-	CAN_BUS_UNKNOWN
 };
 
 /**
@@ -347,7 +345,7 @@ typedef int (*can_recover_t)(const struct device *dev, k_timeout_t timeout);
  * @brief Callback API upon getting the CAN controller state
  * See @a can_get_state() for argument description
  */
-typedef enum can_state (*can_get_state_t)(const struct device *dev,
+typedef int (*can_get_state_t)(const struct device *dev, enum can_state *state,
 			       struct can_bus_err_cnt *err_cnt);
 
 /**
@@ -826,19 +824,21 @@ static inline int z_impl_can_get_max_filters(const struct device *dev, enum can_
  * controller.
  *
  * @param dev          Pointer to the device structure for the driver instance.
+ * @param[out] state   Pointer to the state destination enum or NULL.
  * @param[out] err_cnt Pointer to the err_cnt destination structure or NULL.
  *
- * @retval  state
+ * @retval 0 If successful.
+ * @retval -EIO General input/output error, failed to get state.
  */
-__syscall enum can_state can_get_state(const struct device *dev,
+__syscall int can_get_state(const struct device *dev, enum can_state *state,
 			    struct can_bus_err_cnt *err_cnt);
 
-static inline enum can_state z_impl_can_get_state(const struct device *dev,
+static inline int z_impl_can_get_state(const struct device *dev, enum can_state *state,
 				       struct can_bus_err_cnt *err_cnt)
 {
 	const struct can_driver_api *api = (const struct can_driver_api *)dev->api;
 
-	return api->get_state(dev, err_cnt);
+	return api->get_state(dev, state, err_cnt);
 }
 
 /**

modules/canopennode/CO_driver.c

@@ -406,6 +406,7 @@ void CO_CANverifyErrors(CO_CANmodule_t *CANmodule)
 	enum can_state state;
 	uint8_t rx_overflows;
 	uint32_t errors;
+	int err;
 
 	/*
 	 * TODO: Zephyr lacks an API for reading the rx mailbox
@@ -413,7 +414,11 @@ void CO_CANverifyErrors(CO_CANmodule_t *CANmodule)
 	 */
 	rx_overflows  = 0;
 
-	state = can_get_state(CANmodule->dev, &err_cnt);
+	err = can_get_state(CANmodule->dev, &state, &err_cnt);
+	if (err != 0) {
+		LOG_ERR("failed to get CAN controller state (err %d)", err);
+		return;
+	}
 
 	errors = ((uint32_t)err_cnt.tx_err_cnt << 16) |
 		 ((uint32_t)err_cnt.rx_err_cnt << 8) |

samples/drivers/can/src/main.c

@@ -127,9 +127,16 @@ void poll_state_thread(void *unused1, void *unused2, void *unused3)
 	struct can_bus_err_cnt err_cnt_prev = {0, 0};
 	enum can_state state_prev = CAN_ERROR_ACTIVE;
 	enum can_state state;
+	int err;
 
 	while (1) {
-		state = can_get_state(can_dev, &err_cnt);
+		err = can_get_state(can_dev, &state, &err_cnt);
+		if (err != 0) {
+			printk("Failed to get CAN controller state: %d", err);
+			k_sleep(K_MSEC(100));
+			continue;
+		}
+
 		if (err_cnt.tx_err_cnt != err_cnt_prev.tx_err_cnt ||
 		    err_cnt.rx_err_cnt != err_cnt_prev.rx_err_cnt ||
 		    state_prev != state) {