LED驱动，自动创建设备节点

/**
* @：0xf4028004和0xf4028008是GPIO端口3输出与输出寄存器虚拟地址
* 地址是我直接算出来的，可以用io_p2v()函数实现
* @: __raw_writel()向地址写数据
* @: class_create()创建总线，class_destroy()删除
* @: device_create()创建设备节点,device_destroy()删除
*/

#include <linux/init.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/errno.h>
#include <linux/device.h>
#include <linux/miscdevice.h>
#include <linux/platform_device.h>
#include <linux/types.h>
#include <linux/io.h>
#include <linux/delay.h>
#include <linux/irq.h>
#include <linux/interrupt.h>

#include <asm/uaccess.h>
#include <mach/irq.h>
#include <asm/io.h>
#include <asm/pgtable.h>
#include <asm/page.h>
#include <mach/hardware.h>
#include <mach/platform.h>
#include <mach/lpc32xx_gpio.h>

#define DEVNAME "LED"
#define LED_MAJOR 251

#define P3_SET ((volatile unsigned int) 0xf4028004)
#define P3_CLR ((volatile unsigned int) 0xf4028008)

struct led_dev
{
struct cdev cdev;
unsigned int value;
};

struct led_dev *led_dev;

int led_open(struct inode *inode, struct file *filp)
{
struct led_dev *dev;
dev = container_of(inode->i_cdev, struct led_dev, cdev);
filp->private_data = dev;
try_module_get(THIS_MODULE);
return 0;
}

int led_release(struct inode *inode, struct file *filp)
{
module_put(THIS_MODULE);
return 0;
}

static int led_write(struct file *filp, const char __user *buf, size_t count, loff_t *ppos)
{
struct led_dev *dev = filp->private_data;
if(copy_from_user(&(dev->value), buf , 1))
{
return -EFAULT;
}
if(dev->value == 1)
__raw_writel(1 << 5, P3_SET);
else
__raw_writel(1 << 5, P3_CLR);
return 1;
}

int led_ioctl(struct inode *inode, struct file *filp, unsigned int cmd, unsigned long arg)
{
struct led_dev *dev = filp->private_data;
switch (cmd)
{
case 0:
dev->value = 0;
__raw_writel(1 << 5, P3_CLR);
break;
case 1:
dev->value = 1;
__raw_writel(1 << 5, P3_SET);
break;
default :
dev->value = 1;
__raw_writel(1 << 5, P3_SET);
break;
}
return 0;
}

struct file_operations led_fops =
{
.owner = THIS_MODULE,
.write = led_write,
.ioctl = led_ioctl,
.open = led_open,
.release = led_release,
};

static void led_setup_cdev(struct led_dev *dev, int index)
{
int err, devno = MKDEV(LED_MAJOR, 0);
cdev_init(&dev->cdev, &led_fops);
dev->cdev.owner = THIS_MODULE;
dev->cdev.ops = &led_fops;
err = cdev_add(&dev->cdev, devno, 1);
if(err)
printk(KERN_NOTICE "Error adding LED");
}

struct class *led_class;
static int __init led_init(void)
{
int i,result;
dev_t dev = MKDEV(LED_MAJOR, 0);
result = register_chrdev_region(dev, 1, DEVNAME);
if(result < 0)
return result;
led_dev = kmalloc(sizeof(struct led_dev), GFP_KERNEL);
if(!led_dev)
{
result = ~ENOMEM;
goto fail;
}
memset(led_dev, 0, sizeof(struct led_dev));
led_setup_cdev(led_dev, 0);
led_class = class_create(THIS_MODULE, "led_class");
device_create(led_class, NULL, MKDEV(LED_MAJOR, 0), "LED","LED%d", 0);
__raw_writel(1 << 5, P3_SET);
for(i = 0; i< 5; i++)
{
msleep(1000);
}
__raw_writel(1 << 5, P3_CLR);
for(i = 0; i < 10; i++)
{
msleep(1000);
}
__raw_writel(1 << 5, P3_SET);
return 0;
fail:
unregister_chrdev_region(dev, 1);
return result;
}

static void __exit led_exit(void)
{
cdev_del(&led_dev->cdev);
device_destroy(led_class, MKDEV(LED_MAJOR, 0));
class_destroy(led_class);
kfree(led_dev);
unregister_chrdev_region(MKDEV(LED_MAJOR, 0), 1);
}

module_init(led_init);
module_exit(led_exit);

MODULE_LICENSE("GPL");