examples/uart_bridge: Add an example for bridging data

Add an example for bridging data between UART0 and UART2.

examples/uart_bridge/.gitignore

@@ -0,0 +1,12 @@
+/Make.dep
+/.depend
+/.built
+/*.asm
+/*.obj
+/*.rel
+/*.lst
+/*.sym
+/*.adb
+/*.lib
+/*.src
+/*.spk

examples/uart_bridge/Kconfig

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+
+config EXAMPLES_UART_BRIDGE
+	tristate "UART Bridge Example"
+	default n
+	---help---
+		Enable the uart_bridge app. This app is bridging data between UART0 and UART2.
+
+if EXAMPLES_UART_BRIDGE
+
+config EXAMPLES_UART_BRIDGE_PROGNAME
+	string "Program name"
+	default "uart_bridge"
+	---help---
+		This is the name of the program that will be use when the NSH ELF
+		program is installed.
+
+config EXAMPLES_UART_BRIDGE_PRIORITY
+	int "uart_bridge task priority"
+	default 100
+
+config EXAMPLES_UART_BRIDGE_STACKSIZE
+	int "uart_bridge stack size"
+	default 2048
+
+endif

examples/uart_bridge/Make.defs

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+
+ifneq ($(CONFIG_EXAMPLES_UART_BRIDGE),)
+CONFIGURED_APPS += uart_bridge
+endif

examples/uart_bridge/Makefile

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+
+include $(APPDIR)/Make.defs
+include $(SDKDIR)/Make.defs
+
+PROGNAME = $(CONFIG_EXAMPLES_UART_BRIDGE_PROGNAME)
+PRIORITY = $(CONFIG_EXAMPLES_UART_BRIDGE_PRIORITY)
+STACKSIZE = $(CONFIG_EXAMPLES_UART_BRIDGE_STACKSIZE)
+MODULE = $(CONFIG_EXAMPLES_UART_BRIDGE)
+
+ASRCS =
+CSRCS =
+MAINSRC = uart_bridge_main.c
+
+include $(APPDIR)/Application.mk

examples/uart_bridge/uart_bridge_main.c

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+/****************************************************************************
+ * examples/uart_bridge/uart_bridge_main.c
+ *
+ *   Copyright 2024 Sony Semiconductor Solutions Corporation
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name of Sony Semiconductor Solutions Corporation nor
+ *    the names of its contributors may be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <poll.h>
+#include <fcntl.h>
+
+/****************************************************************************
+ * Preprocessor Definitions
+ ****************************************************************************/
+
+#define DEV_UART0 "/dev/ttyS0"
+#define DEV_UART2 "/dev/ttyS2"
+
+#define BUFLEN  (256)
+
+/****************************************************************************
+ * Privete Data
+ ****************************************************************************/
+
+static char buf[BUFLEN];
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+int main(int argc, FAR char *argv[])
+{
+  int ret;
+  int uart0;
+  int uart2;
+  struct pollfd pfd[2];
+
+  uart0 = open(DEV_UART0, O_RDWR);
+  uart2 = open(DEV_UART2, O_RDWR);
+
+  if (uart0 < 0 || uart2 < 0)
+    {
+      printf("Could not open device files\n");
+      close(uart0); /* Maybe opened, try close */
+      close(uart2); /* Maybe opened, try close */
+      return -1;
+    }
+
+  fclose(stdin);
+  fclose(stdout);
+
+  while (1)
+    {
+      pfd[0].fd     = uart0;
+      pfd[0].events = POLLIN;
+
+      pfd[1].fd     = uart2;
+      pfd[1].events = POLLIN;
+
+      /* Wait for receiving data from both side */
+
+      poll(pfd, 2, -1);
+
+      /* Check if it receives some from uart0 */
+
+      if (pfd[0].revents & POLLIN)
+        {
+          ret = read(uart0, buf, BUFLEN);
+          write(uart2, buf, ret);
+        }
+
+      /* Check if it receives some from uart2 */
+
+      if (pfd[1].revents & POLLIN)
+        {
+          ret = read(uart2, buf, BUFLEN);
+          write(uart0, buf, ret);
+        }
+    }
+
+  /* Never reach here, but just in case */
+
+  close(uart0);
+  close(uart2);
+
+  return 0;
+}