148 lines
4.2 KiB
C
148 lines
4.2 KiB
C
/* skeleton.c */
|
|
#include <linux/cdev.h> /* needed for char device driver */
|
|
#include <linux/fs.h> /* needed for device drivers */
|
|
#include <linux/init.h> /* needed for macros */
|
|
#include <linux/kernel.h> /* needed for debugging */
|
|
#include <linux/module.h> /* needed by all modules */
|
|
#include <linux/moduleparam.h> /* needed for module parameters */
|
|
#include <linux/slab.h> /* needed for dynamic memory management */
|
|
#include <linux/uaccess.h> /* needed to copy data to/from user */
|
|
|
|
static int instances = 3;
|
|
module_param(instances, int, 0);
|
|
|
|
#define BUFFER_SZ 10000
|
|
static char** buffers = 0;
|
|
|
|
static int skeleton_open(struct inode* i, struct file* f)
|
|
{
|
|
pr_info("skeleton : open operation... major:%d, minor:%d\n",
|
|
imajor(i),
|
|
iminor(i));
|
|
|
|
if (iminor(i) >= instances) {
|
|
return -EFAULT;
|
|
}
|
|
|
|
if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) != 0) {
|
|
pr_info("skeleton : opened for reading & writing...\n");
|
|
} else if ((f->f_mode & FMODE_READ) != 0) {
|
|
pr_info("skeleton : opened for reading...\n");
|
|
} else if ((f->f_mode & FMODE_WRITE) != 0) {
|
|
pr_info("skeleton : opened for writing...\n");
|
|
}
|
|
|
|
f->private_data = buffers[iminor(i)];
|
|
pr_info("skeleton: private_data=%p\n", f->private_data);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int skeleton_release(struct inode* i, struct file* f)
|
|
{
|
|
pr_info("skeleton: release operation...\n");
|
|
|
|
return 0;
|
|
}
|
|
|
|
static ssize_t skeleton_read(struct file* f,
|
|
char __user* buf,
|
|
size_t count,
|
|
loff_t* off)
|
|
{
|
|
// compute remaining bytes to copy, update count and pointers
|
|
ssize_t remaining = BUFFER_SZ - (ssize_t)(*off);
|
|
char* ptr = (char*)f->private_data + *off;
|
|
if (count > remaining) count = remaining;
|
|
*off += count;
|
|
|
|
// copy required number of bytes
|
|
if (copy_to_user(buf, ptr, count) != 0) count = -EFAULT;
|
|
|
|
pr_info("skeleton: read operation... read=%ld\n", count);
|
|
|
|
return count;
|
|
}
|
|
|
|
static ssize_t skeleton_write(struct file* f,
|
|
const char __user* buf,
|
|
size_t count,
|
|
loff_t* off)
|
|
{
|
|
// compute remaining space in buffer and update pointers
|
|
ssize_t remaining = BUFFER_SZ - (ssize_t)(*off);
|
|
|
|
// check if still remaining space to store additional bytes
|
|
if (count >= remaining) count = -EIO;
|
|
|
|
// store additional bytes into internal buffer
|
|
if (count > 0) {
|
|
char* ptr = f->private_data + *off;
|
|
*off += count;
|
|
ptr[count] = 0; // make sure string is null terminated
|
|
if (copy_from_user(ptr, buf, count)) count = -EFAULT;
|
|
}
|
|
|
|
pr_info("skeleton: write operation... private_data=%p, written=%ld\n",
|
|
f->private_data,
|
|
count);
|
|
|
|
return count;
|
|
}
|
|
|
|
static struct file_operations skeleton_fops = {
|
|
.owner = THIS_MODULE,
|
|
.open = skeleton_open,
|
|
.read = skeleton_read,
|
|
.write = skeleton_write,
|
|
.release = skeleton_release,
|
|
};
|
|
|
|
static dev_t skeleton_dev;
|
|
static struct cdev skeleton_cdev;
|
|
|
|
static int __init skeleton_init(void)
|
|
{
|
|
int i;
|
|
int status = -EFAULT;
|
|
|
|
if (instances <= 0) return -EFAULT;
|
|
|
|
status = alloc_chrdev_region(&skeleton_dev, 0, instances, "mymodule");
|
|
if (status == 0) {
|
|
cdev_init(&skeleton_cdev, &skeleton_fops);
|
|
skeleton_cdev.owner = THIS_MODULE;
|
|
status = cdev_add(&skeleton_cdev, skeleton_dev, instances);
|
|
}
|
|
|
|
if (status == 0) {
|
|
buffers = kzalloc(sizeof(char*) * instances, GFP_KERNEL);
|
|
for (i = 0; i < instances; i++)
|
|
buffers[i] = kzalloc(BUFFER_SZ, GFP_KERNEL);
|
|
}
|
|
|
|
pr_info("Linux module skeleton loaded\n");
|
|
pr_info("The number of instances: %d\n", instances);
|
|
return status;
|
|
}
|
|
|
|
static void __exit skeleton_exit(void)
|
|
{
|
|
int i;
|
|
|
|
cdev_del(&skeleton_cdev);
|
|
unregister_chrdev_region(skeleton_dev, instances);
|
|
|
|
for (i = 0; i < instances; i++) kfree(buffers[i]);
|
|
kfree(buffers);
|
|
|
|
pr_info("Linux module skeleton unloaded\n");
|
|
}
|
|
|
|
module_init(skeleton_init);
|
|
module_exit(skeleton_exit);
|
|
|
|
MODULE_AUTHOR("Daniel Gachet <daniel.gachet@hefr.ch>");
|
|
MODULE_DESCRIPTION("Module skeleton");
|
|
MODULE_LICENSE("GPL");
|