Imbus/kernelmod_demo
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Imbus 2025-10-16 15:08:16 +02:00
parent 83db8ec77e
commit 40295d6d45
1 changed files with 68 additions and 48 deletions
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116
chardev/chardev.c
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@ -1,9 +1,18 @@
#include "linux/fs.h" #include "linux/fs.h"
#include "linux/types.h" #include "linux/types.h"
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/uaccess.h>
#include <linux/cdev.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/gpio/consumer.h> #include <linux/gpio/consumer.h>
#include <linux/init.h> #include <linux/init.h>
#include <linux/irq.h>
#include <linux/kernel.h> #include <linux/kernel.h>
#include <linux/module.h> #include <linux/module.h>
#include <linux/poll.h>
/* /*
* Last compiled with Linux 6.14.5-300.fc42.x86_64 * Last compiled with Linux 6.14.5-300.fc42.x86_64
@ -15,98 +24,109 @@ MODULE_VERSION("0.0.1");
MODULE_AUTHOR("Imbus"); MODULE_AUTHOR("Imbus");
MODULE_LICENSE("GPL"); MODULE_LICENSE("GPL");
#define DEVICE_NAME "hello_cdev"
// Since were dynamically assigned a major device number, we will store it here // Since were dynamically assigned a major device number, we will store it here
static int major; static int major;
static char text[64]; static char text[64];
static struct class *cls;
// Regular forward decls // Regular forward decls
static ssize_t my_read(struct file *f, char __user *u, size_t l, loff_t *o); static ssize_t my_read(struct file *f, char __user *u, size_t l, loff_t *o);
static ssize_t my_write(struct file *, const char __user *, size_t, loff_t *); static ssize_t my_write(struct file *, const char __user *, size_t, loff_t *);
static int my_open(struct inode *, struct file *); static int my_open(struct inode *, struct file *);
static int my_release(struct inode *, struct file *); static int my_release(struct inode *, struct file *);
// See: https://elixir.bootlin.com/linux/v6.14.5/source/include/linux/fs.h#L2131 // See: https://elixir.bootlin.com/linux/v6.14.5/source/include/linux/fs.h#L2131
static struct file_operations fops = { static struct file_operations fops = {
.read = my_read, .write = my_write, .open = my_open, .release = my_release}; .read = my_read,
.write = my_write,
.open = my_open,
.release = my_release,
};
static ssize_t my_write(struct file *filp, const char __user *user_buf, static ssize_t my_write(struct file *filp, const char __user *user_buf, size_t len, loff_t *off) {
size_t len, loff_t *off) { pr_info("hello_cdev - Write is called by %s...\n", current->comm);
printk(KERN_INFO "hello_cdev - Write is called by %s...\n", current->comm);
int not_copied, delta, int not_copied, delta, to_copy = (len + *off) < sizeof(text) ? len : (sizeof(text) - *off);
to_copy = (len + *off) < sizeof(text) ? len : (sizeof(text) - *off);
if (*off >= sizeof(text)) if (*off >= sizeof(text))
return 0; return 0;
not_copied = copy_from_user(text, user_buf, to_copy); not_copied = copy_from_user(text, user_buf, to_copy);
delta = to_copy - not_copied; delta = to_copy - not_copied;
if (not_copied) if (not_copied)
pr_warn("hello_cdev - Could only copy %d bytes\n", delta); pr_warn("hello_cdev - Could only copy %d bytes\n", delta);
*off = delta; *off = delta;
return delta; return delta;
} }
static ssize_t my_read(struct file *filp, char __user *user_buf, size_t len, static ssize_t my_read(struct file *filp, char __user *user_buf, size_t len, loff_t *off) {
loff_t *off) { pr_info("hello_cdev - Read is called\n");
printk(KERN_INFO "hello_cdev - Read is called\n");
int not_copied, delta, int not_copied, delta, to_copy = (len + *off) < sizeof(text) ? len : (sizeof(text) - *off);
to_copy = (len + *off) < sizeof(text) ? len : (sizeof(text) - *off);
if (*off >= sizeof(text)) if (*off >= sizeof(text))
return 0; return 0;
not_copied = copy_to_user(user_buf, text, to_copy); not_copied = copy_to_user(user_buf, text, to_copy);
delta = to_copy - not_copied; delta = to_copy - not_copied;
if (not_copied) if (not_copied)
pr_warn("hello_cdev - Could only copy %d bytes\n", delta); pr_warn("hello_cdev - Could only copy %d bytes\n", delta);
*off = delta; *off = delta;
return delta; return delta;
} }
static int my_open(struct inode *inode, struct file *filp) { static int my_open(struct inode *inode, struct file *filp) {
pr_info("hello-cdev - Major %d, Minor %d\n", imajor(inode), iminor(inode)); pr_info("hello-cdev - Major %d, Minor %d\n", imajor(inode), iminor(inode));
pr_info("hello-cdev - filp->f_pos: %lld\n", filp->f_pos);
pr_info("hello-cdev - filp->f_mode: 0x%x\n", filp->f_mode);
pr_info("hello-cdev - filp->f_flags: 0x%x\n", filp->f_flags);
pr_info("hello-cdev - filp->f_pos: %lld\n", filp->f_pos); return 0;
pr_info("hello-cdev - filp->f_mode: 0x%x\n", filp->f_mode);
pr_info("hello-cdev - filp->f_flags: 0x%x\n", filp->f_flags);
return 0;
} }
static int my_release(struct inode *inode, struct file *filp) { static int my_release(struct inode *inode, struct file *filp) {
pr_info("hello-cdev - Closed \n"); pr_info("hello-cdev - Closed \n");
return 0; return 0;
} }
/** /**
* @brief Called on load * @brief Called on load
*/ */
static int __init demo_mod_init(void) { static int __init demo_mod_init(void) {
major = register_chrdev(0, "hello_cdev", &fops); major = register_chrdev(0, DEVICE_NAME, &fops);
if (major < 0) { if (major < 0) {
printk(KERN_INFO "hello_cdev - Error registering chrdev\n"); pr_info("hello_cdev - Error registering chrdev\n");
return major; return major;
} }
printk(KERN_INFO "hello_cdev - Major nbr %d loaded successfully...", major); pr_info("I was assigned major number %d.\n", major);
return 0;
cls = class_create(DEVICE_NAME);
device_create(cls, NULL, MKDEV(major, 0), NULL, DEVICE_NAME);
pr_info("Device created on /dev/%s\n", DEVICE_NAME);
pr_info("hello_cdev - Major nbr %d loaded successfully...", major);
return 0;
} }
/** /**
* @brief Called on unload * @brief Called on unload
*/ */
static void __exit demo_mod_exit(void) { static void __exit demo_mod_exit(void) {
unregister_chrdev(major, "hello_cdev"); device_destroy(cls, MKDEV(major, 0));
printk(KERN_INFO "hello_cdev - unloaded successfully..."); class_destroy(cls);
unregister_chrdev(major, DEVICE_NAME);
pr_info("hello_cdev - unloaded successfully...");
} }
module_init(demo_mod_init); module_init(demo_mod_init);