简单的GPIO驱动代码,C代码库,德仔网

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【C】简单的GPIO驱动
作者:简单的GPIO驱动模板 / 发布于2011/6/7/ 720
#include <linux/module.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/cdev.h>
#include <linux/slab.h>
#include <asm/io.h>
#include <asm/system.h>
#include <asm/uaccess.h></div>
<div>define DEVICE_NAME "GPIODEVICE"//定义设备名
#define GPIO_MAJOR 231//定义主设备号
#defineGPIO_MAGIC 0xBB //定义幻数</div>
<div>//定义操作
#defineCMD_SOME _IO(GPIO_MAGIC, 0)</div>
<div>//设置主设备号
static int gpio_major = GPIO_MAJOR;
//static dev_t devno = MKDEV(GPIO_MAJOR, 0);</div>
<div>//定义设备结构体
struct gpio_dev
{
struct cdev cdev;
struct semaphore sem;//定义信号量
};</div>
<div>struct gpio_dev *gpio_devp;</div>
<div>/////////////////////////////////////////////////////
//open函数
static int gpio_open(struct inode *inode, struct file *filp)
{
struct gpio_dev *dev;
dev = container_of(inode->i_cdev, struct gpio_dev, cdev);//通过结构体成员指针找到对应结构体的指针
filp->private_data = dev;//将设备结构体指针赋给文件私有数据指针
printk("gpio device opened\n");
//TODO
return 0;
}
<div>//release函数
int gpio_release(struct inode *inode, struct file *filp)
{
printk("gpio device released\n");
//TODO
return 0;
}
<div>//read函数
static ssize_t gpio_read(struct file *filp, char __user *buf, size_t count, loff_t *offp)
{
struct gpio_dev *dev = filp->private_data;
down(&dev->sem);//获得信号量
printk("gpio device readed\n");
//TODO
up(&dev->sem);//释放信号量
return 0;
}
<div>//write函数
static ssize_t gpio_write(struct file *filp, const char __user *buf, size_t size, loff_t *ppos)
{
struct gpio_dev *dev = filp->private_data;
down(&dev->sem);
printk("led write\n");
//TODO
up(&dev->sem);
return 0;
}
<div>//ioctl函数
static int gpio_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
{
switch (cmd)
{
case CMD_SOME:
//TODO
return 0;
default:
return -EINVAL;
}
}
<div>//file_operations
static struct file_operations gpio_fops =
{
.owner = THIS_MODULE,
.open = gpio_open,
.release = gpio_release,
.read = gpio_read,
.write = gpio_write,
.ioctl = gpio_ioctl,
};</div>
<div>//初始化并注册cdev
static void gpio_setup_cdev(struct gpio_dev *dev, int index)
{
int err;
int devno = MKDEV(gpio_major, index);</div>
<div>//初始化cdev,建立与fops的连接
cdev_init(&dev->cdev, &gpio_fops);
dev->cdev.owner = THIS_MODULE;
dev->cdev.ops = &gpio_fops;</div>
<div>//向系统增加一个cdev
err = cdev_add(&dev->cdev, devno, 1);
if (err)
printk("Error %d adding gpio device", err);
}
<div>static int gpio_init(void)
{
int result;
dev_t devno = MKDEV(gpio_major, 0); //创建设备号</div>
<div>//如果定义了设备号,就静态注册,如果没定义就动态注册设备号
if (gpio_major)
{
result = register_chrdev_region(devno, 1, DEVICE_NAME);
}
else
{
result = alloc_chrdev_region(&devno, 0, 1, DEVICE_NAME);
gpio_major = MAJOR(devno);
}
if (result < 0)
{
printk("Can't register\n");
return result;
}
<div>//分配内存
gpio_devp = kmalloc(sizeof(struct gpio_dev), GFP_KERNEL);</div>
if (!gpio_devp)
{
result = -ENOMEM;
unregister_chrdev_region(devno, 1);
return result;
}
<div>memset(gpio_devp, 0, sizeof(struct gpio_dev));
gpio_setup_cdev(gpio_devp, 0);</div>
<div>//初始化信号量
init_MUTEX(&gpio_devp->sem);
printk("gpio device init\n");
return 0;
}
<div>//exit函数
static void gpio_exit(void)
{
cdev_del(&gpio_devp->cdev);
kfree(gpio_devp);
unregister_chrdev_region(MKDEV(gpio_major, 0), 1);
printk("gpio device exit\n");
}
<div>module_init(gpio_init);
module_exit(gpio_exit);</div>
<div>MODULE_AUTHOR("yisen");
MODULE_DESCRIPTION("GPIO Driver"); // 一些描述信息
MODULE_LICENSE("GPL");</div>
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