drivers: serial: native_tty: config_get support

This commit adds config_get support for native_tty. This is helpful as
some driver code (e.g. u_blox m8) will error out if they can't read the
current configuration.

Signed-off-by: Vytautas Virvičius <vytautas@virvicius.dev>

Author: vytvir

drivers/serial/uart_native_tty.c

@@ -130,6 +130,74 @@ static int native_tty_conv_to_bottom_cfg(struct native_tty_bottom_cfg *bottom_cf
 	return 0;
 }
 
+/**
+ * @brief Convert from native_tty_bottom_cfg to uart_config
+ *
+ * @param bottom_cfg
+ * @param cfg
+ *
+ * @return 0 on success, negative errno otherwise.
+ */
+int native_tty_conv_from_bottom_cfg(int fd, struct uart_config *cfg)
+{
+	struct native_tty_bottom_cfg bottom_cfg;
+	int rc = 0;
+
+	native_tty_read_bottom_cfg(fd, &bottom_cfg);
+	if (rc != 0) {
+		return rc;
+	}
+
+	cfg->baudrate = bottom_cfg.baudrate;
+
+	switch (bottom_cfg.parity) {
+	case NTB_PARITY_NONE:
+		cfg->parity = UART_CFG_PARITY_NONE;
+		break;
+	case NTB_PARITY_ODD:
+		cfg->parity = UART_CFG_PARITY_ODD;
+		break;
+	case NTB_PARITY_EVEN:
+		cfg->parity = UART_CFG_PARITY_EVEN;
+		break;
+	default:
+		return -ENOTSUP;
+	}
+
+	switch (bottom_cfg.stop_bits) {
+	case NTB_STOP_BITS_1:
+		cfg->stop_bits = UART_CFG_STOP_BITS_1;
+		break;
+	case NTB_STOP_BITS_2:
+		cfg->stop_bits = UART_CFG_STOP_BITS_2;
+		break;
+	default:
+		return -ENOTSUP;
+	}
+
+	switch (bottom_cfg.data_bits) {
+	case NTB_DATA_BITS_5:
+		cfg->data_bits = UART_CFG_DATA_BITS_5;
+		break;
+	case NTB_DATA_BITS_6:
+		cfg->data_bits = UART_CFG_DATA_BITS_6;
+		break;
+	case NTB_DATA_BITS_7:
+		cfg->data_bits = UART_CFG_DATA_BITS_7;
+		break;
+	case NTB_DATA_BITS_8:
+		cfg->data_bits = UART_CFG_DATA_BITS_8;
+		break;
+	default:
+		return -ENOTSUP;
+	}
+
+	cfg->flow_ctrl = UART_CFG_FLOW_CTRL_NONE;
+
+	return 0;
+}
+
+
 /*
  * @brief Output a character towards the serial port
  *
@@ -177,6 +245,21 @@ static int native_tty_configure(const struct device *dev, const struct uart_conf
 	return native_tty_configure_bottom(fd, &bottom_cfg);
 }
 
+static int native_tty_config_get(const struct device *dev, struct uart_config *cfg)
+{
+	int fd = ((struct native_tty_data *)dev->data)->fd;
+	int rc = 0;
+
+	rc = native_tty_conv_from_bottom_cfg(fd, cfg);
+	if (rc) {
+		WARN("Could not convert native tty bottom cfg to uart config\n");
+		return rc;
+	}
+
+	return 0;
+}
+
+
 #ifdef CONFIG_UART_INTERRUPT_DRIVEN
 static int native_tty_uart_fifo_fill(const struct device *dev,
 				     const uint8_t *tx_data,
@@ -375,6 +458,7 @@ static DEVICE_API(uart, native_tty_uart_driver_api) = {
 	.poll_in = native_tty_uart_poll_in,
 #ifdef CONFIG_UART_USE_RUNTIME_CONFIGURE
 	.configure = native_tty_configure,
+	.config_get = native_tty_config_get,
 #endif
 #ifdef CONFIG_UART_INTERRUPT_DRIVEN
 	.fifo_fill        = native_tty_uart_fifo_fill,

drivers/serial/uart_native_tty_bottom.c

@@ -90,6 +90,36 @@ static inline void native_tty_baud_speed_set(struct termios *ter, int baudrate)
 	ERROR("Could not set baudrate, as %d is not supported.\n", baudrate);
 }
 
+/**
+ * @brief Get the baud rate speed from the termios structure
+ *
+ * @param ter
+ * @param baudrate
+ *
+ * @return 0 on success, -1 on error
+ */
+static inline int native_tty_baud_speed_get(const struct termios *ter, uint32_t *baudrate)
+{
+	speed_t ispeed = cfgetispeed(ter);
+	speed_t ospeed = cfgetospeed(ter);
+
+	if (ispeed != ospeed) {
+		ERROR("Input and output baud rates differ: %d vs %d\n", ispeed, ospeed);
+		return -1;
+	}
+
+	for (int i = 0; i < ARRAY_SIZE(baudrate_lut); i++) {
+		if (baudrate_lut[i].termios_baudrate == ispeed) {
+			*baudrate = baudrate_lut[i].baudrate;
+			return 0;
+		}
+	}
+
+	ERROR("Unsupported termios baudrate: %d\n", ispeed);
+	return -1;
+}
+
+
 /**
  * @brief Set parity setting in the termios structure
  *
@@ -117,6 +147,27 @@ static inline void native_tty_baud_parity_set(struct termios *ter,
 	}
 }
 
+/**
+ * @brief Get the parity setting from the termios structure
+ *
+ * @param ter
+ * @param parity
+ *
+ * @return 0 on success
+ */
+static inline int native_tty_baud_parity_get(const struct termios *ter,
+					     enum native_tty_bottom_parity *parity)
+{
+	if ((ter->c_cflag & PARENB) == 0) {
+		*parity = NTB_PARITY_NONE;
+	} else if (ter->c_cflag & PARODD) {
+		*parity = NTB_PARITY_ODD;
+	} else {
+		*parity = NTB_PARITY_EVEN;
+	}
+	return 0;
+}
+
 /**
  * @brief Set the number of stop bits in the termios structure
  *
@@ -140,6 +191,22 @@ static inline void native_tty_stop_bits_set(struct termios *ter,
 	}
 }
 
+/**
+ * @brief Get the number of stop bits from the termios structure
+ *
+ * @param ter
+ * @param stop_bits
+ *
+ * @return 0 on success
+ */
+static inline int native_tty_stop_bits_get(const struct termios *ter,
+					   enum native_tty_bottom_stop_bits *stop_bits)
+{
+	*stop_bits = (ter->c_cflag & CSTOPB) ? NTB_STOP_BITS_2 : NTB_STOP_BITS_1;
+	return 0;
+}
+
+
 /**
  * @brief Set the number of data bits in the termios structure
  *
@@ -175,6 +242,38 @@ static inline void native_tty_data_bits_set(struct termios *ter,
 	ter->c_cflag |= data_bits_to_set;
 }
 
+/**
+ * @brief Get the number of data bits from the termios structure
+ *
+ * @param ter
+ * @param data_bits
+ *
+ * @return 0 on success, -1 if unsupported
+ */
+static inline int native_tty_data_bits_get(const struct termios *ter,
+					   enum native_tty_bottom_data_bits *data_bits)
+{
+	switch (ter->c_cflag & CSIZE) {
+	case CS5:
+		*data_bits = NTB_DATA_BITS_5;
+		break;
+	case CS6:
+		*data_bits = NTB_DATA_BITS_6;
+		break;
+	case CS7:
+		*data_bits = NTB_DATA_BITS_7;
+		break;
+	case CS8:
+		*data_bits = NTB_DATA_BITS_8;
+		break;
+	default:
+		ERROR("Unsupported data bits setting in termios.\n");
+		return -1;
+	}
+	return 0;
+}
+
+
 int native_tty_poll_bottom(int fd)
 {
 	struct pollfd pfd = { .fd = fd, .events = POLLIN };
@@ -252,3 +351,42 @@ int native_tty_configure_bottom(int fd, struct native_tty_bottom_cfg *cfg)
 
 	return 0;
 }
+
+int native_tty_read_bottom_cfg(int fd, struct native_tty_bottom_cfg *cfg)
+{
+	struct termios ter;
+	int rc = 0;
+
+	rc = tcgetattr(fd, &ter);
+	if (rc != 0) {
+		int err = 0;
+
+		err = errno;
+		WARN("Could not read terminal driver settings: %s\n", strerror(err));
+		return -err;
+	}
+
+	rc = native_tty_baud_speed_get(&ter, &cfg->baudrate);
+	if (rc != 0) {
+		return rc;
+	}
+
+	rc = native_tty_baud_parity_get(&ter, &cfg->parity);
+	if (rc != 0) {
+		return rc;
+	}
+
+	rc = native_tty_data_bits_get(&ter, &cfg->data_bits);
+	if (rc != 0) {
+		return rc;
+	}
+
+	rc = native_tty_stop_bits_get(&ter, &cfg->stop_bits);
+	if (rc != 0) {
+		return rc;
+	}
+
+	cfg->flow_ctrl = NTB_FLOW_CTRL_NONE;
+
+	return 0;
+}

drivers/serial/uart_native_tty_bottom.h

@@ -86,6 +86,16 @@ int native_tty_open_tty_bottom(const char *pathname);
  */
 int native_tty_configure_bottom(int fd, struct native_tty_bottom_cfg *cfg);
 
+/**
+ * @brief Read bottom tty configuration
+ *
+ * @param fd
+ * @param cfg
+ *
+ * @return 0 on success, negative value on error
+ */
+int native_tty_read_bottom_cfg(int fd, struct native_tty_bottom_cfg *cfg);
+
 #ifdef __cplusplus
 }
 #endif