Hi Kevin,
As you know serial ports can be opened, configured and read/write operations can be performed using open(), tcsetattr(), read() and write() system calls, as in the below sample code. Here tcsetattr() in turn calls ioctl() system call, I think. But all these tcsetattr()/ioctl()/read()/write() corresponding calls to the driver are implemented in the base class and are not exposed as virtual functions in derived IOUserUSBSerial() class.
So if I need to call/send any specific custom request to the driver with a special IOCTL code, what are the options available to the user is my question.
This is the sample user app code which uses system calls to access the serial ports.
BEGIN-->
const char *portname = "/dev/cu.usbserial-YOURDEVICEID";
int serial_port = open(portname, O_RDWR | O_NOCTTY | O_SYNC);
// Check for errors opening the serial port
if (serial_port < 0) {
printf("Error %i from open: %s\n", errno, strerror(errno));
return 1;
}
// Configure the serial port settings
struct termios tty;
if (tcgetattr(serial_port, &tty) != 0) {
printf("Error %i from tcgetattr: %s\n", errno, strerror(errno));
return 1;
}
cfsetospeed(&tty, B9600); // Set output baud rate (e.g., 9600)
cfsetispeed(&tty, B9600); // Set input baud rate
tty.c_cflag |= (CLOCAL | CREAD); // Enable receiver, ignore modem control lines
tty.c_cflag &= ~PARENB; // No parity
tty.c_cflag &= ~CSTOPB; // One stop bit
tty.c_cflag &= ~CSIZE; // Clear all size bits
tty.c_cflag |= CS8; // 8 data bits
tty.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG); // Raw input
tty.c_oflag &= ~OPOST; // Raw output
// Apply the settings
if (tcsetattr(serial_port, TCSANOW, &tty) != 0) {
printf("Error %i from tcsetattr: %s\n", errno, strerror(errno));
return 1;
}
// Write data to the serial port
char msg[] = "Hello, serial port!\n";
write(serial_port, msg, strlen(msg));
// Read data from the serial port (example)
char read_buf[256];
int num_bytes = read(serial_port, read_buf, sizeof(read_buf) - 1);
if (num_bytes < 0) {
printf("Error %i from read: %s\n", errno, strerror(errno));
} else if (num_bytes > 0) {
read_buf[num_bytes] = '\0'; // Null-terminate the string
printf("Received: %s\n", read_buf);
}
close(serial_port); // Close the serial port
<--END
So, my requirement is if I need to call
ioctl(serial_port, MY_IOCTL_REQUEST, &myargs,...)
what is the corresponding code/method that needs to be overridden in my driver (.dext) whose IOClass is IOUserSerial and the driver's base class is IOUserUSBSerial.
Thanks in advance.
