drivers: can: Add get_max_filters API

The maximum number of concurrent filters depends on the hardware and
the driver implementation. This API allows the application to obtain
the maximum number of available filters.

Signed-off-by: Martin Jäger <martin@libre.solar>

drivers/can/can_loopback.c

@@ -236,6 +236,13 @@ int can_loopback_get_core_clock(const struct device *dev, uint32_t *rate)
 	return 0;
 }
 
+int can_loopback_get_max_filters(const struct device *dev, enum can_ide id_type)
+{
+	ARG_UNUSED(id_type);
+
+	return CONFIG_CAN_MAX_FILTER;
+}
+
 static const struct can_driver_api can_api_funcs = {
 	.set_mode = can_loopback_set_mode,
 	.set_timing = can_loopback_set_timing,
@@ -248,6 +255,7 @@ static const struct can_driver_api can_api_funcs = {
 #endif
 	.register_state_change_isr = can_loopback_register_state_change_isr,
 	.get_core_clock = can_loopback_get_core_clock,
+	.get_max_filters = can_loopback_get_max_filters,
 	.timing_min = {
 		.sjw = 0x1,
 		.prop_seg = 0x01,

drivers/can/can_mcp2515.c

@@ -314,6 +314,12 @@ static int mcp2515_get_core_clock(const struct device *dev, uint32_t *rate)
 	return 0;
 }
 
+int mcp2515_get_max_filters(const struct device *dev, enum can_ide id_type)
+{
+	ARG_UNUSED(id_type);
+
+	return CONFIG_CAN_MAX_FILTER;
+}
 
 static int mcp2515_set_timing(const struct device *dev,
 			      const struct can_timing *timing,
@@ -785,6 +791,7 @@ static const struct can_driver_api can_api_funcs = {
 #endif
 	.register_state_change_isr = mcp2515_register_state_change_isr,
 	.get_core_clock = mcp2515_get_core_clock,
+	.get_max_filters = mcp2515_get_max_filters,
 	.timing_min = {
 		.sjw = 0x1,
 		.prop_seg = 0x01,

drivers/can/can_mcux_flexcan.c

@@ -127,6 +127,13 @@ static int mcux_flexcan_get_core_clock(const struct device *dev, uint32_t *rate)
 	return clock_control_get_rate(config->clock_dev, config->clock_subsys, rate);
 }
 
+int mcux_flexcan_get_max_filters(const struct device *dev, enum can_ide id_type)
+{
+	ARG_UNUSED(id_type);
+
+	return CONFIG_CAN_MAX_FILTER;
+}
+
 static int mcux_flexcan_set_timing(const struct device *dev,
 				   const struct can_timing *timing,
 				   const struct can_timing *timing_data)
@@ -747,6 +754,7 @@ static const struct can_driver_api mcux_flexcan_driver_api = {
 #endif
 	.register_state_change_isr = mcux_flexcan_register_state_change_isr,
 	.get_core_clock = mcux_flexcan_get_core_clock,
+	.get_max_filters = mcux_flexcan_get_max_filters,
 	/*
 	 * FlexCAN timing limits are specified in the "FLEXCANx_CTRL1 field
 	 * descriptions" table in the SoC reference manual.

drivers/can/can_rcar.c

@@ -981,6 +981,13 @@ static int can_rcar_get_core_clock(const struct device *dev, uint32_t *rate)
 	return 0;
 }
 
+int can_rcar_get_max_filters(const struct device *dev, enum can_ide id_type)
+{
+	ARG_UNUSED(id_type);
+
+	return CONFIG_CAN_RCAR_MAX_FILTER;
+}
+
 static const struct can_driver_api can_rcar_driver_api = {
 	.set_mode = can_rcar_set_mode,
 	.set_timing = can_rcar_set_timing,
@@ -993,6 +1000,7 @@ static const struct can_driver_api can_rcar_driver_api = {
 #endif
 	.register_state_change_isr = can_rcar_register_state_change_isr,
 	.get_core_clock = can_rcar_get_core_clock,
+	.get_max_filters = can_rcar_get_max_filters,
 	.timing_min = {
 		.sjw = 0x1,
 		.prop_seg = 0x00,

drivers/can/can_stm32.c

@@ -412,6 +412,13 @@ int can_stm32_get_core_clock(const struct device *dev, uint32_t *rate)
 	return 0;
 }
 
+int can_stm32_get_max_filters(const struct device *dev, enum can_ide id_type)
+{
+	ARG_UNUSED(id_type);
+
+	return CONFIG_CAN_MAX_FILTER;
+}
+
 static int can_stm32_init(const struct device *dev)
 {
 	const struct can_stm32_config *cfg = DEV_CFG(dev);
@@ -1105,6 +1112,7 @@ static const struct can_driver_api can_api_funcs = {
 #endif
 	.register_state_change_isr = can_stm32_register_state_change_isr,
 	.get_core_clock = can_stm32_get_core_clock,
+	.get_max_filters = can_stm32_get_max_filters,
 	.timing_min = {
 		.sjw = 0x1,
 		.prop_seg = 0x00,

drivers/can/can_stm32fd.c

@@ -38,6 +38,15 @@ int can_stm32fd_get_core_clock(const struct device *dev, uint32_t *rate)
 	return 0;
 }
 
+int can_stm32fd_get_max_filters(const struct device *dev, enum can_ide id_type)
+{
+	if (id_type == CAN_STANDARD_IDENTIFIER) {
+		return NUM_STD_FILTER_DATA;
+	} else {
+		return NUM_EXT_FILTER_DATA;
+	}
+}
+
 void can_stm32fd_clock_enable(void)
 {
 	LL_RCC_SetFDCANClockSource(LL_RCC_FDCAN_CLKSOURCE_PCLK1);
@@ -175,6 +184,7 @@ static const struct can_driver_api can_api_funcs = {
 	.recover = can_mcan_recover,
 #endif
 	.get_core_clock = can_stm32fd_get_core_clock,
+	.get_max_filters = can_stm32fd_get_max_filters,
 	.register_state_change_isr = can_stm32fd_register_state_change_isr,
 	.timing_min = {
 		.sjw = 0x7f,

include/drivers/can.h

@@ -370,6 +370,9 @@ typedef void(*can_register_state_change_isr_t)(const struct device *dev,
 
 typedef int (*can_get_core_clock_t)(const struct device *dev, uint32_t *rate);
 
+typedef int (*can_get_max_filters_t)(const struct device *dev,
+				     enum can_ide id_type);
+
 #ifndef CONFIG_CAN_WORKQ_FRAMES_BUF_CNT
 #define CONFIG_CAN_WORKQ_FRAMES_BUF_CNT 4
 #endif
@@ -404,6 +407,7 @@ __subsystem struct can_driver_api {
 	can_get_state_t get_state;
 	can_register_state_change_isr_t register_state_change_isr;
 	can_get_core_clock_t get_core_clock;
+	can_get_max_filters_t get_max_filters;
 	/* Min values for the timing registers */
 	struct can_timing timing_min;
 	/* Max values for the timing registers */
@@ -661,6 +665,31 @@ static inline int z_impl_can_get_core_clock(const struct device *dev,
 	return api->get_core_clock(dev, rate);
 }
 
+/**
+ * @brief Retrieve maximum number of filters
+ *
+ * @param dev Pointer to the device structure for the driver instance.
+ * @param id_type CAN identifier type (standard or extended)
+ *
+ * @retval Number of maximum concurrent filters
+ * @retval -EIO General input / output error, failed to query device
+ * @retval -ENOSYS If this function is not implemented by the driver
+ */
+__syscall int can_get_max_filters(const struct device *dev, enum can_ide id_type);
+
+static inline int z_impl_can_get_max_filters(const struct device *dev,
+					     enum can_ide id_type)
+{
+	const struct can_driver_api *api =
+		(const struct can_driver_api *)dev->api;
+
+	if (api->get_max_filters == NULL) {
+		return -ENOSYS;
+	}
+
+	return api->get_max_filters(dev, id_type);
+}
+
 /**
  * @brief Calculate timing parameters from bitrate and sample point
  *