可否幫忙看看為何insmod執行後tree /sys/class, 並沒有hello device產生
hello.c
#include <linux/device.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/cdev.h>
#include <linux/fs.h>
MODULE_LICENSE("Dual BSD/GPL");
#define DEVNAME "hello"
static dev_t dev;
static struct class *hello_class;
static struct cdev *hello_cdev;
int hello_major = 250;
int hello_minor = 0;
static int hello_open(struct inode *inode,struct file *flp)
{
return 0;
}
static int hello_close(struct inode *inode,struct file *flp)
{
return 0;
}
static struct file_operations hello_fops={
.owner=THIS_MODULE,
.open =hello_open,
.release=hello_close,
};
static int __init hello_init(void)
{
//int error;
//error = alloc_chrdev_region(&dev, 0, 2, "hello");
int error, dev = MKDEV (hello_major, hello_minor);
if (error)
{
printk("hello: alloc_chardev_region failed!\n");
goto out;
}
hello_cdev = cdev_alloc();
if (hello_cdev == NULL)
{
printk("hello: alloc cdev failed!\n");
error = -ENOMEM;
goto out_chrdev;
}
hello_cdev->ops = &hello_fops;
hello_cdev->owner = THIS_MODULE;
error = cdev_add(hello_cdev, dev, 1);
if (error)
{
printk("hello: cdev_add failed!\n");
goto out_cdev;
}
hello_class = class_create(THIS_MODULE, DEVNAME);
if (IS_ERR(hello_class))
{
error = PTR_ERR(hello_class);
goto out_chrdev;
}
device_create(hello_class, NULL, dev , NULL, DEVNAME);
//memset (hello_buf, 0, sizeof(hello_buf));
//memcpy(hello_buf, DEFAULT_MSG, sizeof(DEFAULT_MSG));
printk("hello: Hello World!\n");
return 0;
out_cdev:
cdev_del(hello_cdev);
out_chrdev:
unregister_chrdev_region(hello_cdev->dev, 2);
out:
return error;
}
static void __exit hello_exit(void)
{
device_destroy(hello_class, dev);
class_destroy(hello_class);
unregister_chrdev_region(hello_cdev->dev, 2);
cdev_del(hello_cdev);
printk("hello: Goodbye World\n");
}
Makefile
#
# Makefile for kernel test
#
PWD := $(shell pwd)
KVERSION := $(shell uname -r)
KERNEL_DIR = /usr/src/linux-headers-$(KVERSION)/
MODULE_NAME = hello
obj-m := $(MODULE_NAME).o
all:
make -C $(KERNEL_DIR) M=$(PWD) modules
clean:
make -C $(KERNEL_DIR) M=$(PWD) clean
