How High the Pin of Parallel Port - linux-device-driver

Question

/* Necessary includes for drivers */
#include <linux/init.h>
//#include <linux/config.h>
#include <linux/module.h>
#include <linux/kernel.h> /* printk() */
#include <linux/slab.h> /* kmalloc() */
#include <linux/fs.h> /* everything... */
#include <linux/errno.h> /* error codes */
#include <linux/types.h> /* size_t */
#include <linux/proc_fs.h>
#include <linux/fcntl.h> /* O_ACCMODE */
#include <linux/ioport.h>
#include <asm/system.h> /* cli(), *_flags */
#include <asm/uaccess.h> /* copy_from/to_user */
#include <asm/io.h> /* inb, outb */
MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("Nikunj");
/* Function declaration of parlelport.c */
int parlelport_open(struct inode *inode, struct file *filp);
int parlelport_release(struct inode *inode, struct file *filp);
ssize_t parlelport_read(struct file *filp, char *buf, size_t count, loff_t *f_pos);
ssize_t parlelport_write(struct file *filp, char *buf, size_t count, loff_t *f_pos);
void parlelport_exit(void);
int parlelport_init(void);
/* Structure that declares the common */
/* file access fcuntions */
struct file_operations parlelport_fops = {
read : parlelport_read,
write : parlelport_write,
open : parlelport_open,
release : parlelport_release
};
/* Driver global variables */
/* Major number */
int parlelport_major = 61;
/* Control variable for memory */
/* reservation of the parallel port*/
int port;
module_init(parlelport_init);
module_exit(parlelport_exit);
int parlelport_init(void)
{
int result;
/* Registering device */
result = register_chrdev(parlelport_major, "parlelport", &parlelport_fops);
if (result < 0)
{
printk("<1>parlelport: cannot obtain major number %d\n",parlelport_major);
return result;
}
/* Registering port */
port = check_region(0x378, 1);
if (port)
{
printk("<1>parlelport: cannot reserve 0x378\n");
result = port;
goto fail;
}
request_region(0x378, 1, "parlelport");
printk("<1>Inserting parlelport module\n");
return 0;
fail:
parlelport_exit();
return result;
}
void parlelport_exit(void)
{
/* Make major number free! */
unregister_chrdev(parlelport_major, "parlelport");
/* Make port free! */
if (!port)
{
release_region(0x378,1);
}
printk("<1>Removing parlelport module\n");
}
int parlelport_open(struct inode *inode, struct file *filp)
{
/* Success */
return 0;
}
int parlelport_release(struct inode *inode, struct file *filp)
{
/* Success */
return 0;
}
ssize_t parlelport_read(struct file *filp, char *buf, size_t count, loff_t *f_pos)
{
/* Buffer to read the device */
char parlelport_buffer;
/* Reading port */
parlelport_buffer = inb(0x378);
/* We transfer data to user space */
copy_to_user(buf,&parlelport_buffer,1);
/* We change the reading position as best suits */
if (*f_pos == 0)
{
*f_pos+=1;
return 1;
}
else
{
return 0;
}
}
ssize_t parlelport_write( struct file *filp, char *buf, size_t count, loff_t *f_pos)
{
char *tmp;
/* Buffer writing to the device */
char parlelport_buffer;
tmp=buf+count-1;
copy_from_user(&parlelport_buffer,tmp,1);
/* Writing to the port */
outb(parlelport_buffer,0x378);
return 1;
}
this is the code of parallel port device driver and this is my first c code for that.
Please help me to solve the below problem
i have successfully compile the code and create the .ko file successfully and successfully load in the ubuntu 9.10 OS but thee is no high or low the pin so please help me

Answer 1

How you are checking answer?? After installed module do
dmesg

Answer 2

Actually you can not acquire region at 0x378. Because by default system allocate this one to parport0.
Do cat /proc/ioports so you will find that at 0x378 there is parport0.
You can directly write on that address (0x378), without using that checking and requesting.
My suggestion is that don't directly go in complex form. In write function just write
outb(0x378,1) and check (by inserting hardware having LEDs) LED on/off on data pins.