/*
 * IOPortTest uCHobby 8.20.2010
 * sets bit 0 and 1 of the Parallel port Data pins high for 10mS.
 * These two bits are pins 2 and 3 on the standard DB25 connector.
 *
 * Two methods are shown, the first using IOCTL calls,the second
 * uses direct I/O writes. To use direct writes we need to know
 * the IO port addresses, I found mine by hunting through boot
 * up messages.
 */

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>

#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/io.h>
#include <linux/ppdev.h>
#include <linux/parport.h>

void ToggleWithIOCTL(void);
void ToggleWithIORaw(void);

int main() {
	ToggleWithIOCTL();  //Use the IOCTL driver method to toggle the pins
	sleep(1);           //Sleep for one second
	ToggleWithIORaw();  //This time use the raw IO methods to toggle the pins
	exit(EXIT_SUCCESS);
}

//Use IOCTL calls to control printer port IO - Works well.
void ToggleWithIOCTL (void){
	int portHandle;  //Handle to reference the parallel port as a file

	portHandle=open("/dev/parport0", O_RDWR);  //Open the port.
	if (portHandle == -1) {  //Did the port fail to open?
		perror ("open");     //Could not open, output error with an explanation
	}

    if (portHandle != -1) { //if the port opened OK, claim it for our purposes
    	if (ioctl (portHandle, PPCLAIM)) { //Were we able to claim it?
    		perror ("PPCLAIM");  //Cannot claim port, output an explanation
			close (portHandle);  //Close the file we had
			portHandle=-1;       //set the handle to show not-valid
		}
	 }

	if(portHandle != -1){  //Do we have a valid file handle?
		int iTemp=0x03;  //Just need to turn on the lower two bits, D0 and D1, 
                         //leave D2-D7 low. Use a temp because we have to pass 
                         //by reference.
		if(ioctl(portHandle, PPWDATA,&iTemp)) { //Set the port value
			printf("PPWDATA"); //Write failed, output error with an explanation
		}

		usleep(10000);  //Sleep for 10 milliseconds, value is in microseconds.

		iTemp=0x00;  //turn off all the bits D0-D7
		if(ioctl(portHandle, PPWDATA,&iTemp)) {  //Set the port value
			printf("PPWDATA"); //Write failed, output error with an explanation
		}
	}

	if(ioctl(portHandle, PPRELEASE)) { //Try and release the ppdev file handle
		printf("PPRELEASE");  //Did not release, output an explanation
	}
	close(portHandle);
}

#define PPDEV_BASEPORT   0xC400  //Found by hunting in boot messages near ppdev
#define PPDEV_DATA    (PPDEV_BASEPORT+0)  //Define constant for the DATA port
#define PPDEV_STATUS  (PPDEV_BASEPORT+1)  //Define constant for the STATUS port
#define PPDEV_CONTROL (PPDEV_BASEPORT+2)  //Define constant for the CONTROL port

#define TRUE  1 //These should be defined somewhere in a generic module, 
#define FALSE 0 //for now I'm defining them here.

//Use raw I/O method to control printer port IO
void ToggleWithIORaw (void) {
	int portOK=FALSE;

	if(iopl(3)){            //Request permission to access IO ports using raw 
                            //functions. This may not be necessary
		perror("iopl");     //No permission, output error with an explanation
	}
	else { //We got permission
	  /* Get access to the ports */
	  if (ioperm(PPDEV_BASEPORT, 3, 1)) {  //Get permission to access the 
                                           //specific ports we need.
	      perror("ioperm");   //No permission, output error with an explanation
		  exit(EXIT_FAILURE); //We are done, bad code should not exit here
	  }
	  else {
		  portOK=TRUE;  //We have permission and have claimed the ports we need
	  }
	}

	if (portOK) {
		outb(0x03, PPDEV_DATA);  //Set the lower two bits of DATA register.
	    usleep(10000);           //Sleep for 10 milliseconds, in microseconds.
	    outb(0x00, PPDEV_DATA);  //turn off all the bits D0-D7
	}

	if (ioperm(PPDEV_BASEPORT, 3, 0)) {  //Release the IO ports
	   perror("ioperm");  //Could not release, output error with an explanation
	   portOK=FALSE; //We had some trouble ending port access.
	}
//	return(portOK);  //not returning value right now.
}