yaakov/scream-driver
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works now, clean me up pls

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Yaakov 2024-08-11 14:42:56 +10:00
parent 252c5eaf2a
commit 0b2fa3282f
1 changed files with 44 additions and 51 deletions
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121
scream.c
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@ -3,6 +3,7 @@
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/uaccess.h>
MODULE_AUTHOR("Yaakov");
@ -20,87 +21,79 @@ static struct cdev scream_cdev;
static int scream_device_open(struct inode*, struct file*);
static int scream_device_release(struct inode*, struct file*);
static ssize_t scream_device_read(struct file*, char*, size_t, loff_t*);
static ssize_t scream_device_write(struct file*, const char*, size_t, loff_t*);
static struct file_operations fops = {
static const struct file_operations scream_fops = {
.owner = THIS_MODULE,
.open = scream_device_open,
.read = scream_device_read,
.write = scream_device_write,
.release = scream_device_release,
};
static int __init scream_module_init(void) {
printk(KERN_INFO "[scream] loading...\n");
static int __init scream_module_init(void)
{
int err;
dev_t dev;
if (alloc_chrdev_region(&major_number, 0, 1, DEVICE_NAME) < 0) {
printk(KERN_ALERT "[scream] Failed to register a major number.\n");
return major_number;
}
err = alloc_chrdev_region(&dev, 0, 1, DEVICE_NAME);
major_number = MAJOR(dev);
scream_class = class_create(CLASS_NAME);
if (IS_ERR(scream_class)) {
unregister_chrdev_region(major_number, 1);
printk(KERN_ALERT "[scream] Failed to register device class\n");
return PTR_ERR(scream_class);
}
scream_device = device_create(scream_class, NULL, MKDEV(major_number, 0), NULL, DEVICE_NAME);
if (IS_ERR(scream_device)) {
class_destroy(scream_class);
unregister_chrdev_region(major_number, 1);
printk(KERN_ALERT "[scream] Failed to create the device\n");
return PTR_ERR(scream_device);
}
cdev_init(&scream_cdev, &scream_fops);
scream_cdev.owner = THIS_MODULE;
printk(KERN_INFO "[scream] %s/%s device registered.", CLASS_NAME, DEVICE_NAME);
cdev_add(&scream_cdev, MKDEV(major_number, 0), 1);
cdev_init(&scream_cdev, &fops);
int add_result = cdev_add(&scream_cdev, MKDEV(major_number, 0), 1);
if (add_result < 0) {
device_create(scream_class, NULL, MKDEV(major_number, 0), NULL, DEVICE_NAME);
return 0;
}
static void __exit scream_module_exit(void)
{
device_destroy(scream_class, MKDEV(major_number, 0));
class_unregister(scream_class);
class_destroy(scream_class);
unregister_chrdev_region(major_number, 1);
printk(KERN_ALERT "[scream] Failed to add cdev: %d\n", add_result);
return -1;
unregister_chrdev_region(MKDEV(major_number, 0), MINORMASK);
}
static int scream_device_open(struct inode *inode, struct file *file)
{
printk(KERN_INFO "[scream] Device open\n");
return 0;
}
static int scream_device_release(struct inode *inode, struct file *file)
{
printk(KERN_INFO "[scream] Device close\n");
return 0;
}
static ssize_t scream_device_read(struct file *file, char __user *buf, size_t count, loff_t *offset)
{
uint8_t rand;
for (size_t i = 0; i < count; i++)
{
get_random_bytes(&rand, sizeof(rand));
char value;
if (rand > 200) {
value = 'A';
} else {
value = 'a';
}
printk(KERN_INFO "[scream] loaded.\n");
return 0;
}
if (copy_to_user(buf + i, &value, 1)) {
return -EFAULT;
}
}
static void __exit scream_module_exit(void) {
printk(KERN_INFO "[scream] exiting...\n");
cdev_del(&scream_cdev);
device_destroy(scream_class, MKDEV(major_number, 0));
class_destroy(scream_class);
unregister_chrdev_region(major_number, 1);
printk(KERN_INFO "[scream] done.\n");
}
static int scream_device_open(struct inode* node, struct file* file)
{
printk(KERN_INFO "[scream] opening device.\n");
return 0;
}
static int scream_device_release(struct inode* node, struct file* file)
{
printk(KERN_INFO "[scream] releasing device.\n");
return 0;
}
static ssize_t scream_device_read(struct file* file, char* __user user_buffer, size_t size, loff_t* offset)
{
printk(KERN_INFO "[scream] reading from device.\n");
return 0;
}
static ssize_t scream_device_write(struct file* file, const char* __user user_buffer, size_t size, loff_t* offset)
{
printk(KERN_INFO "[scream] writing to device.\n");
return 0;
return count;
}
module_init(scream_module_init);