#include <linux/module.h> #include <linux/fs.h> #include <linux/major.h> #include <linux/capability.h> #include <asm/uaccess.h> #include <linux/cdev.h> static ssize_t sample_char_read(struct file * file, char __user * buf, size_t count, loff_t *ppos) { printk("sample_char_read size(%ld)\n", count); return 0; } static ssize_t sample_char_write(struct file *filp, const char *buf, size_t size, loff_t *offp) { printk("sample_char_write size(%ld)\n", size); return size; } int sample_char_open(struct inode *inode, struct file *filp) { printk("sample_char_open\n"); return 0; } int sample_char_release(struct inode *inode, struct file *filp) { printk("sample_char_release\n"); return 0; } static struct file_operations sample_char_fops = { read: sample_char_read, write: sample_char_write, open: sample_char_open, release: sample_char_release, }; #define sample_major_number 249 #define max_minors 1 static struct cdev char_cdev; static dev_t dev; int init_module(void) { int ret = 0; dev = MKDEV(sample_major_number, 0); printk("\nLoading the sample char device driver\n"); ret = register_chrdev_region(dev, max_minors, "sample_char"); if (ret) { printk("register_chrdev_region Error\n"); goto error; } cdev_init(&char_cdev, &sample_char_fops); ret = cdev_add(&char_cdev, dev, max_minors); if (ret) { printk("cdev_add Error\n"); goto error_region; } return 0; error_region: unregister_chrdev_region(dev, max_minors); error: return ret; } void cleanup_module(void) { cdev_del(&char_cdev); unregister_chrdev_region(dev, max_minors); printk("\nUnloading the sample char device driver\n"); }
Sunday, 18 May 2014
static MAJOR number allocation in character device driver in linux
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device driver
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