From 07656bf95c255b51cde4b5a6cd2b1eb9fdd744bd Mon Sep 17 00:00:00 2001
From: Will Hedgecock <will.hedgecock@gmail.com>
Date: Mon, 17 Jan 2022 21:56:40 -0600
Subject: [PATCH] Create new RS485 test case

---
 src/test/c/Makefile    |  2 +
 src/test/c/testRS485.c | 93 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 95 insertions(+)
 create mode 100644 src/test/c/testRS485.c

diff --git a/src/test/c/Makefile b/src/test/c/Makefile
index 2d4396b..1c7e05c 100644
--- a/src/test/c/Makefile
+++ b/src/test/c/Makefile
@@ -35,6 +35,8 @@ $(BUILD_DIR) :
 # Build rules for all tests
 testOpenClose : $(BUILD_DIR)/testOpenClose.o $(BUILD_DIR)/PosixHelperFunctions.o
 	$(COMPILE) $(LDFLAGS) $(LIBRARIES) -o $@ $^
+testRS485 : $(BUILD_DIR)/testRS485.o
+	$(COMPILE) $(LDFLAGS) $(LIBRARIES) -o $@ $^
 testEnumeratePosix : $(BUILD_DIR)/testEnumeratePosix.o $(BUILD_DIR)/PosixHelperFunctions.o
 	$(COMPILE) $(LDFLAGS) $(LIBRARIES) -o $@ $^
 testEnumerateWindows : $(BUILD_DIR)/testEnumerateWindows.o $(BUILD_DIR)/WindowsHelperFunctions.o
diff --git a/src/test/c/testRS485.c b/src/test/c/testRS485.c
new file mode 100644
index 0000000..9d10560
--- /dev/null
+++ b/src/test/c/testRS485.c
@@ -0,0 +1,93 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/file.h>
+#include <sys/ioctl.h>
+#include <termios.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <linux/serial.h>
+#define termios asmtermios
+#define termio asmtermio
+#define winsize asmwinsize
+#include <asm/ioctls.h>
+#include <asm/termios.h>
+#undef termio
+#undef termios
+#undef winsize
+
+int main(int argc, char *argv[])
+{
+	// Ensure that port handle was passed in
+	if (argc != 2)
+	{
+		printf("Usage: ./testRS485 /dev/port/path\n");
+		return 0;
+	}
+	const char *portName = argv[1];
+
+	// Open serial port
+	int portHandle = open(portName, O_RDWR | O_NOCTTY | O_NONBLOCK | O_CLOEXEC);
+	if (portHandle > 0)
+	{
+		// Ensure that multiple root users cannot access the device simultaneously
+		if (flock(portHandle, LOCK_EX | LOCK_NB))
+		{
+			while (close(portHandle) && (errno == EINTR))
+				errno = 0;
+			portHandle = -1;
+		}
+	}
+	if (portHandle <= 0)
+	{
+		printf("Error opening port at %s\n", portName);
+		return -1;
+	}
+
+	// Attempt to retrieve RS485 configuration from connected device
+	struct serial_rs485 rs485Conf = { 0 };
+	int retVal = ioctl(portHandle, TIOCGRS485, &rs485Conf);
+	if (retVal)
+	{
+		printf("Error retrieving RS485 configuration, Code = %d, Errno = %d\n", retVal, errno);
+		return -2;
+	}
+
+	// Attempt to enable RS485 configuration
+	rs485Conf.flags |= SER_RS485_ENABLED;
+	rs485Conf.flags |= SER_RS485_RTS_ON_SEND;
+	rs485Conf.flags &= ~(SER_RS485_RTS_AFTER_SEND);
+	rs485Conf.flags &= ~(SER_RS485_RX_DURING_TX);
+	rs485Conf.flags &= ~(SER_RS485_TERMINATE_BUS);
+	rs485Conf.delay_rts_before_send = 1;
+	rs485Conf.delay_rts_after_send = 1;
+	retVal = ioctl(portHandle, TIOCSRS485, &rs485Conf);
+	if (retVal)
+	{
+		printf("Error enabling RS485 configuration, Code = %d, Errno = %d\n", retVal, errno);
+		return -3;
+	}
+
+	// Attempt to disable RS485 configuration
+	rs485Conf.flags &= ~SER_RS485_ENABLED;
+	rs485Conf.flags &= ~(SER_RS485_RTS_ON_SEND);
+	rs485Conf.flags |= SER_RS485_RTS_AFTER_SEND;
+	rs485Conf.flags |= SER_RS485_RX_DURING_TX;
+	rs485Conf.flags |= SER_RS485_TERMINATE_BUS;
+	retVal = ioctl(portHandle, TIOCSRS485, &rs485Conf);
+	if (retVal)
+	{
+		printf("Error disabling RS485 configuration, Code = %d, Errno = %d\n", retVal, errno);
+		return -4;
+	}
+
+	// Unblock, unlock, and close the port
+	fsync(portHandle);
+	tcdrain(portHandle);
+	tcflush(portHandle, TCIOFLUSH);
+	flock(portHandle, LOCK_UN | LOCK_NB);
+	while (close(portHandle) && (errno == EINTR))
+		errno = 0;
+	portHandle = -1;
+	return 0;
+}