globalmem: move major to 230 as usbmon holds 250
/*
* a simple char device driver: globalmem without mutex
*
* Copyright (C) 2014 Barry Song (baohua@kernel.org)
*
* Licensed under GPLv2 or later.
*/
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/cdev.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#define GLOBALMEM_SIZE 0x1000
#define MEM_CLEAR 0x1
#define GLOBALMEM_MAJOR 230
static int globalmem_major = GLOBALMEM_MAJOR;
module_param(globalmem_major, int, S_IRUGO);
struct globalmem_dev {
struct cdev cdev;
unsigned char mem[GLOBALMEM_SIZE];
};
struct globalmem_dev *globalmem_devp;
static int globalmem_open(struct inode *inode, struct file *filp)
{
filp->private_data = globalmem_devp;
return 0;
}
static int globalmem_release(struct inode *inode, struct file *filp)
{
return 0;
}
static long globalmem_ioctl(struct file *filp, unsigned int cmd,
unsigned long arg)
{
struct globalmem_dev *dev = filp->private_data;
switch (cmd) {
case MEM_CLEAR:
memset(dev->mem, 0, GLOBALMEM_SIZE);
printk(KERN_INFO "globalmem is set to zero\n");
break;
default:
return -EINVAL;
}
return 0;
}
static ssize_t globalmem_read(struct file *filp, char __user * buf, size_t size,
loff_t * ppos)
{
unsigned long p = *ppos;
unsigned int count = size;
int ret = 0;
struct globalmem_dev *dev = filp->private_data;
if (p >= GLOBALMEM_SIZE)
return 0;
if (count > GLOBALMEM_SIZE - p)
count = GLOBALMEM_SIZE - p;
if (copy_to_user(buf, dev->mem + p, count)) {
ret = -EFAULT;
} else {
*ppos += count;
ret = count;
printk(KERN_INFO "read %u bytes(s) from %lu\n", count, p);
}
return ret;
}
static ssize_t globalmem_write(struct file *filp, const char __user * buf,
size_t size, loff_t * ppos)
{
unsigned long p = *ppos;
unsigned int count = size;
int ret = 0;
struct globalmem_dev *dev = filp->private_data;
if (p >= GLOBALMEM_SIZE)
return 0;
if (count > GLOBALMEM_SIZE - p)
count = GLOBALMEM_SIZE - p;
if (copy_from_user(dev->mem + p, buf, count))
ret = -EFAULT;
else {
*ppos += count;
ret = count;
printk(KERN_INFO "written %u bytes(s) from %lu\n", count, p);
}
return ret;
}
static loff_t globalmem_llseek(struct file *filp, loff_t offset, int orig)
{
loff_t ret = 0;
switch (orig) {
case 0:
if (offset < 0) {
ret = -EINVAL;
break;
}
if ((unsigned int)offset > GLOBALMEM_SIZE) {
ret = -EINVAL;
break;
}
filp->f_pos = (unsigned int)offset;
ret = filp->f_pos;
break;
case 1:
if ((filp->f_pos + offset) > GLOBALMEM_SIZE) {
ret = -EINVAL;
break;
}
if ((filp->f_pos + offset) < 0) {
ret = -EINVAL;
break;
}
filp->f_pos += offset;
ret = filp->f_pos;
break;
default:
ret = -EINVAL;
break;
}
return ret;
}
static const struct file_operations globalmem_fops = {
.owner = THIS_MODULE,
.llseek = globalmem_llseek,
.read = globalmem_read,
.write = globalmem_write,
.unlocked_ioctl = globalmem_ioctl,
.open = globalmem_open,
.release = globalmem_release,
};
static void globalmem_setup_cdev(struct globalmem_dev *dev, int index)
{
int err, devno = MKDEV(globalmem_major, index);
cdev_init(&dev->cdev, &globalmem_fops);
dev->cdev.owner = THIS_MODULE;
err = cdev_add(&dev->cdev, devno, 1);
if (err)
printk(KERN_NOTICE "Error %d adding globalmem%d", err, index);
}
static int __init globalmem_init(void)
{
int ret;
dev_t devno = MKDEV(globalmem_major, 0);
if (globalmem_major)
ret = register_chrdev_region(devno, 1, "globalmem");
else {
ret = alloc_chrdev_region(&devno, 0, 1, "globalmem");
globalmem_major = MAJOR(devno);
}
if (ret < 0)
return ret;
globalmem_devp = kzalloc(sizeof(struct globalmem_dev), GFP_KERNEL);
if (!globalmem_devp) {
ret = -ENOMEM;
goto fail_malloc;
}
globalmem_setup_cdev(globalmem_devp, 0);
return 0;
fail_malloc:
unregister_chrdev_region(devno, 1);
return ret;
}
module_init(globalmem_init);
static void __exit globalmem_exit(void)
{
cdev_del(&globalmem_devp->cdev);
kfree(globalmem_devp);
unregister_chrdev_region(MKDEV(globalmem_major, 0), 1);
}
module_exit(globalmem_exit);
MODULE_AUTHOR("Barry Song <baohua@kernel.org>");
MODULE_LICENSE("GPL v2");