Hi!
I've checked in the BIOS of the box that the parallel port (only one) is indeed:
base address = 0x378
irq = 7
mode:bi-directional mode
I try to write a parallel port kernel module that is able to out all 1
to the output port of the parallel port, which is connected to a dummy
device that all output port is connected to ground via a set of LED
diode and the most significant bit of the parallel port is also
connected to the interrupt pin, which will trigger an interrupt, as
described in chapter 9 (communicating with hardware) of the book
"Linux Device Drivers (3rd ed)"
I have already unloaded parport, lp,. parport_pc and one more modules
that are automatically loaded in the kernel and /proc/ioports now
shows that 0x378 to 0x37a is unoccupied.
Then I load my module, which request_region(tem_base, PORT_SIZE,
"tem") at the beginning of init. If error occurs, abort, but if
successful, then I try to set all output bits on by:
mb();
outb_p(0xFF, tem_base);
mb();
The module loads successfully and /proc/ioports shows that 0x378 to
0x37a is now occupied by my module. However the LED of my dummy
module fails to glow. What else do I need to do to write to the
output port?
However when the original system-provided modules are not unloaded, I
can successfully turn on all LEDs from the user space by executing
this program:
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <asm/io.h>
#define base 0x378 /* printer port base address */
#define value 255 /* numeric value to send to printer port */
int main(int argc, char **argv)
{
if (ioperm(base,1,1))
fprintf(stderr, "Couldn't get the port at %x\n", base), exit(1);
outb(value, base);
}
Here is the sourcecode of my toy module:
#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/list.h>
#include <asm/uaccess.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/proc_fs.h>
#include <linux/wait.h>
#include <linux/interrupt.h>
#include <asm/system.h>
#include <asm/io.h>
#include <linux/ioport.h>
#define PORT_SIZE 3
struct cdev *tem_dev;
MODULE_LICENSE("GPL");
MODULE_AUTHOR("codemaster");
MODULE_DESCRIPTION("dummy parport module");
/**
* module_param interface is provided for specifying the tem_major,
* tem_minor and tem_dev_count variables, but this customarization is not yet
* supported and therefore will be reset to default values at the beginning
* of the tem_init_module function.
*/
int tem_major; /* major number of module */
int tem_minor; /* minor number of module */
int tem_dev_count; /* number of devices */
dev_t dev; /* the device */
module_param(tem_major, int, S_IRUGO);
MODULE_PARM_DESC(tem_major, "major number");
module_param(tem_minor, int, S_IRUGO);
MODULE_PARM_DESC(tem_minor, "minor number");
module_param(tem_dev_count, int, S_IRUGO);
MODULE_PARM_DESC(tem_dev_count, "number of devices");
unsigned long tem_base = 0x378;
/* module_param(tem_base, unsigned long, S_IRUGO); */
/**
* This function opens the virtual disk, if it is opened in the write-only
* mode, all memory pages will be freed.
*/
int tem_open(struct inode *inode, struct file *filp) {
return 0; /* success */
}
/**
* This function releases the virtual disk, but nothing needs to be done
* in this case.
*/
int tem_release (struct inode *inode, struct file *filp) {
return 0;
}
ssize_t tem_read (struct file *filp, char __user *buf, size_t count,
loff_t *f_pos) {
printk(KERN_WARNING "in tem_read");
return count;
}
/**
* This function writes from the user buffer to the virtual disk of this
* module
*/
ssize_t tem_write(struct file *filp, const char __user *buf, size_t count,
loff_t *f_pos) {
return count;
}
/**
* The ioctl function, which nothing needs to be done in this case.
*/
int tem_ioctl (struct inode *inode, struct file *filp, unsigned cmd,
unsigned long arg) {
return 0;
}
struct file_operations tem_fops = {
.owner = THIS_MODULE,
.read = tem_read,
.write = tem_write,
.ioctl = tem_ioctl,
.open = tem_open,
.release = tem_release,
};
/**
* Initialise the module and create the master device
*/
int __init tem_init_module(void){
int result;
/* initialization of tem global variables, which resets values
possibily modified by module_param, which modifications are currently
not yet supported */
tem_major = 0;
tem_minor = 0;
tem_dev_count = 1;
if (NULL == request_region(tem_base, PORT_SIZE, "tem")) {
printk(KERN_WARNING "mod_tem: can't get I/O port address 0x%03lx\n",
tem_base);
return -EBUSY;
/* return -ENODEV; */
}
mb();
outb_p(0xFF, tem_base); /* to set all output bits in base_addr to high */
mb();
dev = MKDEV(tem_major, tem_minor);
if (tem_major) {
result = register_chrdev_region(dev, tem_dev_count, "tem");
} else {
result = alloc_chrdev_region(&dev, tem_minor, tem_dev_count, "tem");
tem_major = MAJOR(dev);
}
if (result < 0) {
printk(KERN_WARNING "mod_tem: can't get major number\n");
release_region(tem_base, PORT_SIZE);
return result;
}
tem_dev = cdev_alloc();
tem_dev->ops = &tem_fops;
tem_dev->owner = THIS_MODULE;
result = cdev_add(tem_dev, dev, tem_dev_count);
if (result < 0) {
printk(KERN_WARNING "mod_tem: can't add tem to the system\n");
unregister_chrdev_region(dev, tem_dev_count);
release_region(tem_base, PORT_SIZE);
return result;
}
printk(KERN_WARNING "Hello world from Template Module\n");
return 0;
}
/**
* Finalise the module
*/
void __exit tem_exit_module(void){
cdev_del(tem_dev);
unregister_chrdev_region(dev, tem_dev_count);
release_region(tem_base, PORT_SIZE);
printk(KERN_WARNING "Good bye from Template Module\n");
}
module_init(tem_init_module);
module_exit(tem_exit_module);
Thanks!
#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/list.h>
#include <asm/uaccess.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/proc_fs.h>
#include <linux/wait.h>
#include <linux/interrupt.h>
#include <asm/system.h>
#include <asm/io.h>
#include <linux/ioport.h>
#define PORT_SIZE 3
struct cdev *tem_dev;
MODULE_LICENSE("GPL");
MODULE_AUTHOR("abc");
MODULE_DESCRIPTION("dummy parport module");
/**
* module_param interface is provided for specifying the tem_major,
* tem_minor and tem_dev_count variables, but this customarization is not yet
* supported and therefore will be reset to default values at the beginning
* of the tem_init_module function.
*/
int tem_major; /* major number of module */
int tem_minor; /* minor number of module */
int tem_dev_count; /* number of devices */
dev_t dev; /* the device */
module_param(tem_major, int, S_IRUGO);
MODULE_PARM_DESC(tem_major, "major number");
module_param(tem_minor, int, S_IRUGO);
MODULE_PARM_DESC(tem_minor, "minor number");
module_param(tem_dev_count, int, S_IRUGO);
MODULE_PARM_DESC(tem_dev_count, "number of devices");
unsigned long tem_base = 0x378;
/* module_param(tem_base, unsigned long, S_IRUGO); */
/**
* This function opens the virtual disk, if it is opened in the write-only
* mode, all memory pages will be freed.
*/
int tem_open(struct inode *inode, struct file *filp) {
return 0; /* success */
}
/**
* This function releases the virtual disk, but nothing needs to be done
* in this case.
*/
int tem_release (struct inode *inode, struct file *filp) {
return 0;
}
ssize_t tem_read (struct file *filp, char __user *buf, size_t count,
loff_t *f_pos) {
printk(KERN_WARNING "in tem_read");
return count;
}
/**
* This function writes from the user buffer to the virtual disk of this
* module
*/
ssize_t tem_write(struct file *filp, const char __user *buf, size_t count,
loff_t *f_pos) {
return count;
}
/**
* The ioctl function, which nothing needs to be done in this case.
*/
int tem_ioctl (struct inode *inode, struct file *filp, unsigned cmd,
unsigned long arg) {
return 0;
}
struct file_operations tem_fops = {
.owner = THIS_MODULE,
.read = tem_read,
.write = tem_write,
.ioctl = tem_ioctl,
.open = tem_open,
.release = tem_release,
};
/**
* Initialise the module and create the master device
*/
int __init tem_init_module(void){
int result;
/* initialization of tem global variables, which resets values
possibily modified by module_param, which modifications are currently
not yet supported */
tem_major = 0;
tem_minor = 0;
tem_dev_count = 1;
if (NULL == request_region(tem_base, PORT_SIZE, "tem")) {
printk(KERN_WARNING "mod_tem: can't get I/O port address 0x%03lx\n",
tem_base);
return -EBUSY;
/* return -ENODEV; */
}
mb();
outb_p(0xFF, tem_base); /* to set all output bits in base_addr to high */
mb();
dev = MKDEV(tem_major, tem_minor);
if (tem_major) {
result = register_chrdev_region(dev, tem_dev_count, "tem");
} else {
result = alloc_chrdev_region(&dev, tem_minor, tem_dev_count, "tem");
tem_major = MAJOR(dev);
}
if (result < 0) {
printk(KERN_WARNING "mod_tem: can't get major number\n");
release_region(tem_base, PORT_SIZE);
return result;
}
tem_dev = cdev_alloc();
tem_dev->ops = &tem_fops;
tem_dev->owner = THIS_MODULE;
result = cdev_add(tem_dev, dev, tem_dev_count);
if (result < 0) {
printk(KERN_WARNING "mod_tem: can't add tem to the system\n");
unregister_chrdev_region(dev, tem_dev_count);
release_region(tem_base, PORT_SIZE);
return result;
}
printk(KERN_WARNING "Hello world from Template Module\n");
return 0;
}
/**
* Finalise the module
*/
void __exit tem_exit_module(void){
cdev_del(tem_dev);
unregister_chrdev_region(dev, tem_dev_count);
release_region(tem_base, PORT_SIZE);
printk(KERN_WARNING "Good bye from Template Module\n");
}
module_init(tem_init_module);
module_exit(tem_exit_module);
Attachment:
Makefile
Description: Binary data
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <asm/io.h>
#define base 0x378 /* printer port base address */
#define value 255 /* numeric value to send to printer port */
int main(int argc, char **argv)
{
if (ioperm(base,1,1))
fprintf(stderr, "Couldn't get the port at %x\n", base), exit(1);
outb(value, base);
}
