app: Implement AT+IFC command handling

Adds the ability to turn hardware flow control
on and off at runtime.

Signed-off-by: Mariano Goluboff <mariano.goluboff@nordicsemi.no>

Author: mgolu

app/src/sm_at_commands.c

@@ -271,11 +271,13 @@ STATIC int handle_at_clac(enum at_parser_cmd_type cmd_type, struct at_parser *,
 		 *	* AT+IPR
 		 *	* AT+CMUX
 		 *	* AT+CGDATA
+		 *	* AT+IFC
 		 */
 		if ((strncasecmp(cmd, "AT+", strlen("AT+")) == 0 &&
 		     strncasecmp(cmd, "AT+IPR", strlen("AT+IPR")) != 0 &&
 		     strncasecmp(cmd, "AT+CMUX", strlen("AT+CMUX")) != 0 &&
-		     strncasecmp(cmd, "AT+CGDATA", strlen("AT+CGDATA")) != 0) ||
+		     strncasecmp(cmd, "AT+CGDATA", strlen("AT+CGDATA")) != 0 &&
+			 strncasecmp(cmd, "AT+IFC", strlen("AT+IFC")) != 0) ||
 		    strncasecmp(cmd, "AT%%", strlen("AT%%")) == 0) {
 			continue;
 		}

app/src/sm_uart_handler.c

@@ -653,3 +653,71 @@ static int handle_at_ipr(enum at_parser_cmd_type cmd_type, struct at_parser *par
 
 	return -SILENT_AT_COMMAND_RET;
 }
+SM_AT_CMD_CUSTOM(ifc, "AT+IFC", handle_at_ifc);
+static int handle_at_ifc(enum at_parser_cmd_type cmd_type, struct at_parser *parser,
+			  uint32_t param_count)
+{
+	int err;
+	struct uart_config cfg;
+	uint16_t flow_ctrl;
+
+	err = uart_config_get(sm_uart_dev, &cfg);
+	if (err) {
+		LOG_ERR("uart_config_get: %d", err);
+		return err;
+	}
+
+	if (cmd_type == AT_PARSER_CMD_TYPE_READ) {
+		rsp_send("\r\n+IFC: %u\r\n", cfg.flow_ctrl & UART_CFG_FLOW_CTRL_RTS_CTS ? 2 : 0);
+		return 0;
+	}
+
+	if (cmd_type == AT_PARSER_CMD_TYPE_TEST) {
+		rsp_send("\r\n+IFC: (0,2)\r\n");
+		return 0;
+	}
+
+	if (cmd_type != AT_PARSER_CMD_TYPE_SET || param_count != 2) {
+		return -EINVAL;
+	}
+
+	if (sm_cmux_is_started()) {
+		LOG_ERR("Cannot change flow control while CMUX is active.");
+		return -EBUSY;
+	}
+
+	err = at_parser_num_get(parser, 1, &flow_ctrl);
+	if (err) {
+		return err;
+	}
+
+	/* Convert standard AT values of 0 and 2 to the right definition */
+	if (flow_ctrl == 0) {
+		cfg.flow_ctrl = UART_CFG_FLOW_CTRL_NONE;
+	} else if (flow_ctrl == 2) {
+		cfg.flow_ctrl = UART_CFG_FLOW_CTRL_RTS_CTS;
+	} else {
+		LOG_ERR("Unsupported flow control: %u", flow_ctrl);
+		return -EINVAL;
+	}
+
+	rsp_send_ok();
+	
+	err = modem_pipe_close(&sm_pipe.pipe, K_SECONDS(1));
+	if (err) {
+		LOG_ERR("modem_pipe_close: %d", err);
+		return err;
+	}
+	err = uart_configure(sm_uart_dev, &cfg);
+	if (err) {
+		LOG_ERR("uart_configure: %d", err);
+		return err;
+	}
+	err = modem_pipe_open(&sm_pipe.pipe, K_SECONDS(1));
+	if (err) {
+		LOG_ERR("modem_pipe_open: %d", err);
+		return err;
+	}
+
+	return -SILENT_AT_COMMAND_RET;
+}

doc/app/at_generic.rst

@@ -101,6 +101,107 @@ Example
    +IPR: (),(115200,230400,460800,921600,1000000)
    OK
 
+|SM| UART flow control AT+IFC
+=============================
+
+The ``AT+IFC`` command sets the UART flow control.
+
+Set command
+-----------
+
+The set command sets the UART flow control.
+
+Syntax
+~~~~~~
+
+::
+
+   AT+IFC=<flow_control>
+
+The ``<flow_control>`` parameter is an integer value specifying the desired flow control:
+
+- 0: Disable flow control
+- 2: Enable RTS/CTS flow control
+
+.. note::
+
+   The flow control change takes effect after the modem responds with ``OK``.
+   The host must switch to the new flow control settings to continue communication.
+
+Example
+~~~~~~~
+
+Disable flow control.
+
+::
+
+   AT+IFC=0
+   OK
+
+Enable RTS/CTS flow control.
+
+::
+
+   AT+IFC=2
+   OK
+
+Read command
+------------
+
+The read command reads the current UART flow control.
+
+Syntax
+~~~~~~
+
+::
+
+   AT+IFC?
+
+Response syntax
+~~~~~~~~~~~~~~~
+
+::
+
+   +IFC: <flow_control>
+
+Example
+~~~~~~~
+
+::
+
+   AT+IFC?
+   +IFC: 0
+   OK
+
+Test command
+------------
+
+The test command lists the supported flow control modes.
+
+Syntax
+~~~~~~
+
+::
+
+   AT+IFC=?
+
+Response syntax
+~~~~~~~~~~~~~~~
+
+::
+
+   +IFC: (list of supported flow control modes)
+
+Example
+~~~~~~~
+
+::
+
+   AT+IFC=?
+   +IFC: (0,2)
+   OK
+
+
 |SM| echo E0/E1
 ===============