I/O through a digiboard using inb and outb

[Raja.Hayek@xxxxxxxxxxxxxx]

I have a digiboard and have been successful
doing I/O through by using the standard method of creating devices (using
mknod), configuring the ports (using setserial) and then opening the ports
and performing I/O (using open("/dev/ttyS....,) and read() and write()).

However, when I try to use the port
for I/O from within a module in RTAI things do not go so well. Basically,
I am trying to access those ports using memory addresses (which match the
addresses set on the digiboard dipswitches). When load up the RTAI modules
(including this one) , the program does not recognize the port at all.

// some includes up here...

#define  COM3    0x100
               
               
       // the address given to COM3 as per
setserial 

static const int BRDL   = 0;          
               
     // Baud rate divisor register offset
static const int BRDH   = 1;
static const int IER    = 1;
static const int LCR    = 3;        
               
       // line control register

static const int LCR_data = 0x03;          
             // 8 bits,
no parity, 1 stop bit 
static const int LCR_access_baudrate = 0x80;        //
allow access to the baud rate divisor registers

static const int baud19200high  = 0;
static const int baud19200low   = 6;

static const int IER_data   = 0;        
               //
disable all COM interrupts 

int init_module(void){ ... }

static void sample_timer(int t){ ... }

static void sample_timer_signal(void)
{ 
        outb(LCR_access_baudrate, COM3+LCR);  
     // COM3: this line causes segmentation fault
        outb(baud19200low, COM3+BRDL);    
           // Setup the baud
rate divisor 
        outb(baud19200high, COM3+BRDH);
        outb(LCR_data, COM3+LCR);      
               
 // Access TX and RX data ports
        outb(IER_data, COM3+IER);      
               
 // Setup interrupt masks

        outb(data_byte,
COM3);

// more code down here... 

Thanks a lot. Any help would be appreciated.

Raja Hayek.