1.驱动代码
/* 关灯 */
/* 开灯 */
/* timer设备结构体 */
struct timer_dev{
dev_t devid; /* 设备号 */
struct cdev cdev; /* 字符设备 */
struct class *class; /* 类 */
struct device *device; /* 设备 */
int major; /* 注设备号 */
int minor; /* 次设备号 */
struct device_node *nd; /* 设备节点 */
int led_gpio; /* 设备树里面的编号 */
struct timer_list timer; /* 设备里面定义一个定时器 */
};
struct timer_dev timerDev; /* 定义LED结构体 */
/* 初始化led */
static int led_init(struct timer_dev *dev)
{
int ret = 0;
/* 1. 获取设备节点 */
dev->nd = of_find_node_by_path("/gpioled");
if( dev->nd == NULL){
ret = -EINVAL;
printk("gpioled node can not found!\r\n");
goto fail_findnd;
}
/* 2. 获取设备所对应的gpio */
/* 注意第三个参数，因为只有一个索引，所以是0 */
dev->led_gpio = of_get_named_gpio(dev->nd, "led-gpios", 0);
if( dev->led_gpio < 0) {
printk("Can't find led gpio \r\n");
ret = -EINVAL;
goto fail_findnd;
}
printk("Led gpio num = %d. \r\n", dev->led_gpio);
/* 3. 获取到IO之后，申请IO */
/* 作用是申请之后，就能知道该IO是否被其他函数占用 */
/* 如果申请失败，说明被战用啦 */
/* 解决方法：1.搜索所需管脚 2.在搜索复用管脚，例如 &gpio1 3 */
ret = gpio_request(dev->led_gpio, "led-gpio");
if(ret) {
printk("Failed to request the led gpio! \r\n");
ret = -EINVAL;
goto fail_findnd;
}
/* 4. 使用IO */
ret = gpio_direction_output(dev->led_gpio, 1); /* 设置输出，默认高电平不点亮 */
if(ret < 0){
printk("Failed to set input or output! \r\n");
goto fail_set_output;
}
/* 5. 输出低电平，点亮LED */
gpio_set_value(dev->led_gpio, 0);
return 0;
/* 错误处理 */
fail_set_output:
gpio_free(dev->led_gpio);
fail_findnd:
return ret;
}
/* 定时器处理函数 */
static void timer_func(unsigned long arg)
{
/* 先取得函数传递的参数 */
struct timer_dev *dev =(struct timer_dev *)arg;
static int sta = 1;
sta = !sta;
gpio_set_value(dev->led_gpio, sta);
/* 这里是再加500ms，每进一次中断就会把中断时间提升500ms，这样可以一直运行 */
mod_timer(&dev->timer, jiffies + msecs_to_jiffies(500));
}
/* 初始化定时器 */
static void mytimer_init(void)
{
/* 初始化定时器 */
init_timer(&timerDev.timer);
/* 定义定时器的中断函数 */
timerDev.timer.function = timer_func;
/* 函数传递的参数 */
timerDev.timer.data = (unsigned long)&timerDev;
/* 定义定时器的周期 */
/* 当前系统定时+500ms周期 */
/* 设定好了之后，过了500ms之后就会进入function */
timerDev.timer.expires = jiffies + msecs_to_jiffies(500);
/* 添加定时器 */
add_timer(&timerDev.timer);
}
static void led_switch(struct timer_dev *dev, u8 sta)
{
if(sta == LEDON) {
gpio_set_value(dev->led_gpio, 0);
}else if(sta == LEDOFF) {
gpio_set_value(dev->led_gpio, 1);
} else {
printk("Error Number! \r\n");
}
}
static int timer_open(struct inode *inode, struct file *filp)
{
filp->private_data = &timerDev;
return 0;
}
static int timer_release(struct inode *inode, struct file *filp)
{
//struct timer_dev *dev = (struct timer_dev *)filp->private_data;
return 0;
}
static ssize_t timer_write(struct file *filp, const char __user *buf, size_t count, loff_t *ppos)
{
int retvalue;
unsigned char databuf[1];
// unsigned char ledstat;
struct timer_dev *dev = (struct timer_dev *)filp->private_data;
retvalue = copy_from_user(databuf, buf, count);
if(retvalue < 0) {
printk("kernel write failed!\r\n");
return -EFAULT;
}
led_switch(dev, databuf[0]);
return 0;
}
static ssize_t timer_read(struct file *filp, char __user *buf,
size_t cnt, loff_t *offt)
{
return 0;
}
/* 字符设备操作集 */
static const struct file_operations timer_fops = {
.owner = THIS_MODULE,
.write = timer_write,
.open = timer_open,
.read = timer_read,
.release = timer_release,
};
/* 模块入口函数 */
static int __init timer_init(void)
{
/* 定义一些所需变量 */
int ret = 0;
/* 1. 注册字符设备驱动 */
timerDev.major = 0;
if(timerDev.major) {
timerDev.devid = MKDEV(timerDev.major, 0);
ret = register_chrdev_region(timerDev.devid, TIMER_CNT, TIMER_NAME);
} else {
alloc_chrdev_region(&timerDev.devid, 0, TIMER_CNT, TIMER_NAME);
timerDev.major = MAJOR(timerDev.devid);
timerDev.minor = MINOR(timerDev.devid);
}
if(ret < 0){
goto fail_devid;
}
printk("Make devid success! \r\n");
printk("major = %d, minor = %d \r\n", timerDev.major, timerDev.minor);
/* 2. 初始化cdev */
timerDev.cdev.owner = THIS_MODULE;
cdev_init(&timerDev.cdev, &timer_fops);
ret = cdev_add(&timerDev.cdev, timerDev.devid, TIMER_CNT);
if (ret < 0){
goto fail_cdev;
} else {
printk("Cdev add sucess! \r\n");
}
/* 3. 自动创建设备节点 */
timerDev.class = class_create(THIS_MODULE, TIMER_NAME);
if(IS_ERR(timerDev.class)) {
ret = PTR_ERR(timerDev.class);
goto fail_class;
} else {
printk("Class create sucess! \r\n");
}
timerDev.device = device_create(timerDev.class, NULL, timerDev.devid, NULL, TIMER_NAME);
if(IS_ERR(timerDev.device)) {
ret = PTR_ERR(timerDev.device);
goto fail_device;
} else {
printk("Device create sucess! \r\n");
}
/* 初始化Led */
ret = led_init(&timerDev);
if(ret < 0) {
goto fail_led_init;
}
/* 初始化定时器 */
mytimer_init();
printk("timerDev init! \r\n");
return 0;
/* 错误处理 */
fail_led_init:
fail_device:
class_destroy(timerDev.class);
fail_class:
cdev_del(&timerDev.cdev);
fail_cdev:
unregister_chrdev_region(timerDev.devid, TIMER_CNT);
fail_devid:
return ret;
}
/* 模块出口函数 */
static void __exit timer_exit(void)
{
/* 关闭定时器 */
del_timer(&timerDev.timer);
/* 关灯 */
gpio_set_value(timerDev.led_gpio, 1);
/* 1. 释放设备号 */
cdev_del(&timerDev.cdev);
/* 2. 注销设备号 */
unregister_chrdev_region(timerDev.devid, TIMER_CNT);
/* 3. 摧毁设备 */
device_destroy(timerDev.class, timerDev.devid);
/* 4.摧毁类 */
class_destroy(timerDev.class);
/* 释放IO， 和上面的申请IO对应 */
gpio_free(timerDev.led_gpio);
printk("timerDev exit! \r\n");
}
/* 模块入口和出口注册 */
module_init(timer_init);
module_exit(timer_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Shao Zheming");
2.使用ioctl
- unlocked_ioctl
提供对程序的控制功能，与应用函数的ioctl对应 - compat_ioctl
64位系统上的unlocked_ioctl - ioctl中的cmd
命令是自己定义的，但是要符合linux规则。
一个cmd被分为了4个段，每一段都有各自的意义，cmd的定义在<linux/ioctl.h>。注：但实际上<linux/ioctl.h>中只是包含了<asm/ioctl.h>，这说明了这是跟平台相关的，ARM的定义在<arch/arm/include/asm/ioctl.h>，但这文件也是包含别的文件<asm-generic/ioctl.h>。
/* 关闭定时器 */
/* 打开定时器 */
/* 设置定时器周期命令 */
/* 关灯 */
/* 开灯 */
/* timer设备结构体 */
struct timer_dev{
dev_t devid; /* 设备号 */
struct cdev cdev; /* 字符设备 */
struct class *class; /* 类 */
struct device *device; /* 设备 */
int major; /* 注设备号 */
int minor; /* 次设备号 */
struct device_node *nd; /* 设备节点 */
int led_gpio; /* 设备树里面的编号 */
struct timer_list timer; /* 设备里面定义一个定时器 */
int timeperiod; /* 定时周期,单位为 ms */
spinlock_t lock; /* 定义自旋锁 */
};
struct timer_dev timerDev; /* 定义LED结构体 */
/* 初始化led */
static int led_init(struct timer_dev *dev)
{
int ret = 0;
/* 1. 获取设备节点 */
dev->nd = of_find_node_by_path("/gpioled");
if( dev->nd == NULL){
ret = -EINVAL;
printk("gpioled node can not found!\r\n");
goto fail_findnd;
}
/* 2. 获取设备所对应的gpio */
/* 注意第三个参数，因为只有一个索引，所以是0 */
dev->led_gpio = of_get_named_gpio(dev->nd, "led-gpios", 0);
if( dev->led_gpio < 0) {
printk("Can't find led gpio \r\n");
ret = -EINVAL;
goto fail_findnd;
}
printk("Led gpio num = %d. \r\n", dev->led_gpio);
/* 3. 获取到IO之后，申请IO */
/* 作用是申请之后，就能知道该IO是否被其他函数占用 */
/* 如果申请失败，说明被战用啦 */
/* 解决方法：1.搜索所需管脚 2.在搜索复用管脚，例如 &gpio1 3 */
ret = gpio_request(dev->led_gpio, "led-gpio");
if(ret) {
printk("Failed to request the led gpio! \r\n");
ret = -EINVAL;
goto fail_findnd;
}
/* 4. 使用IO */
ret = gpio_direction_output(dev->led_gpio, 1); /* 设置输出，默认高电平不点亮 */
if(ret < 0){
printk("Failed to set input or output! \r\n");
goto fail_set_output;
}
/* 5. 输出低电平，点亮LED */
gpio_set_value(dev->led_gpio, 0);
return 0;
/* 错误处理 */
fail_set_output:
gpio_free(dev->led_gpio);
fail_findnd:
return ret;
}
/* 定时器处理函数 */
static void timer_func(unsigned long arg)
{
/* 先取得函数传递的参数 */
struct timer_dev *dev =(struct timer_dev *)arg;
static int sta = 1;
sta = !sta;
gpio_set_value(dev->led_gpio, sta);
/* 这里是再加500ms，每进一次中断就会把中断时间提升500ms，这样可以一直运行 */
mod_timer(&dev->timer, jiffies + msecs_to_jiffies(timerDev.timeperiod));
}
/* 初始化定时器 */
static void mytimer_init(void)
{
/* 初始化定时器 */
init_timer(&timerDev.timer);
/* 初始化定时器的周期为500ms */
timerDev.timeperiod = 500;
/* 定义定时器的中断函数 */
timerDev.timer.function = timer_func;
/* 函数传递的参数 */
timerDev.timer.data = (unsigned long)&timerDev;
/* 定义定时器的周期 */
/* 当前系统定时+500ms周期 */
/* 设定好了之后，过了500ms之后就会进入function */
timerDev.timer.expires = jiffies + msecs_to_jiffies(timerDev.timeperiod);
/* 添加定时器 */
add_timer(&timerDev.timer);
}
static int timer_open(struct inode *inode, struct file *filp)
{
filp->private_data = &timerDev;
return 0;
}
static int timer_release(struct inode *inode, struct file *filp)
{
//struct timer_dev *dev = (struct timer_dev *)filp->private_data;
return 0;
}
static long timer_ioctl (struct file *filp, unsigned int cmd,
unsigned long arg)
{
struct timer_dev *dev = (struct timer_dev *)filp->private_data;
int timerperiod;
unsigned long flags;
switch (cmd) {
case CLOSE_CMD: /* 关闭定时器 */
del_timer_sync(&dev->timer);
break;
case OPEN_CMD: /* 打开定时器 */
spin_lock_irqsave(&dev->lock, flags);
timerperiod = dev->timeperiod;
spin_unlock_irqrestore(&dev->lock, flags);
mod_timer(&dev->timer, jiffies + msecs_to_jiffies(timerperiod));
break;
case SETPERIOD_CMD: /* 设置定时器周期 */
spin_lock_irqsave(&dev->lock, flags);
dev->timeperiod = arg;
spin_unlock_irqrestore(&dev->lock, flags);
mod_timer(&dev->timer, jiffies + msecs_to_jiffies(arg));
break;
default:
break;
}
return 0;
}
/* 字符设备操作集 */
static const struct file_operations timer_fops = {
.owner = THIS_MODULE,
.open = timer_open,
.release = timer_release,
.unlocked_ioctl = timer_ioctl,
};
/* 模块入口函数 */
static int __init timer_init(void)
{
/* 定义一些所需变量 */
int ret = 0;
/* 1. 注册字符设备驱动 */
timerDev.major = 0;
if(timerDev.major) {
timerDev.devid = MKDEV(timerDev.major, 0);
ret = register_chrdev_region(timerDev.devid, TIMER_CNT, TIMER_NAME);
} else {
alloc_chrdev_region(&timerDev.devid, 0, TIMER_CNT, TIMER_NAME);
timerDev.major = MAJOR(timerDev.devid);
timerDev.minor = MINOR(timerDev.devid);
}
if(ret < 0){
goto fail_devid;
}
printk("Make devid success! \r\n");
printk("major = %d, minor = %d \r\n", timerDev.major, timerDev.minor);
/* 2. 初始化cdev */
timerDev.cdev.owner = THIS_MODULE;
cdev_init(&timerDev.cdev, &timer_fops);
ret = cdev_add(&timerDev.cdev, timerDev.devid, TIMER_CNT);
if (ret < 0){
goto fail_cdev;
} else {
printk("Cdev add sucess! \r\n");
}
/* 3. 自动创建设备节点 */
timerDev.class = class_create(THIS_MODULE, TIMER_NAME);
if(IS_ERR(timerDev.class)) {
ret = PTR_ERR(timerDev.class);
goto fail_class;
} else {
printk("Class create sucess! \r\n");
}
timerDev.device = device_create(timerDev.class, NULL, timerDev.devid, NULL, TIMER_NAME);
if(IS_ERR(timerDev.device)) {
ret = PTR_ERR(timerDev.device);
goto fail_device;
} else {
printk("Device create sucess! \r\n");
}
/* 初始化Led */
ret = led_init(&timerDev);
if(ret < 0) {
goto fail_led_init;
}
/* 初始化定时器 */
mytimer_init();
printk("timerDev init! \r\n");
return 0;
/* 错误处理 */
fail_led_init:
fail_device:
class_destroy(timerDev.class);
fail_class:
cdev_del(&timerDev.cdev);
fail_cdev:
unregister_chrdev_region(timerDev.devid, TIMER_CNT);
fail_devid:
return ret;
}
/* 模块出口函数 */
static void __exit timer_exit(void)
{
/* 关闭定时器 */
del_timer(&timerDev.timer);
/* 关灯 */
gpio_set_value(timerDev.led_gpio, 1);
/* 1. 释放设备号 */
cdev_del(&timerDev.cdev);
/* 2. 注销设备号 */
unregister_chrdev_region(timerDev.devid, TIMER_CNT);
/* 3. 摧毁设备 */
device_destroy(timerDev.class, timerDev.devid);
/* 4.摧毁类 */
class_destroy(timerDev.class);
/* 释放IO， 和上面的申请IO对应 */
gpio_free(timerDev.led_gpio);
printk("timerDev exit! \r\n");
}
/* 模块入口和出口注册 */
module_init(timer_init);
module_exit(timer_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Shao Zheming");
3.应用代码
/*
* argc: 应用程序参数个数
* argv[]: 参数是什么，具体的参数，说明参数是字符串的形式
* .chrdevbaseApp <filename> <0:1> 0表示关灯，1表示开灯
* .chrdevbaseApp /dev/led 0 关灯
* .chrdevbaseApp /dev/led 1 开灯
* */
/* 关闭定时器 */
/* 打开定时器 */
/* 设置定时器周期命令 */
int main(int argc, char *argv[])
{
if(argc != 2)
{
printf("Error Usage!\r\n");
return -1;
}
int fd, ret;
char *filename;
unsigned int cmd;
unsigned int arg;
unsigned char str[100];
filename = argv[1];
fd = open(filename, O_RDWR);
if(fd < 0)
{
printf("file %s open failed! \r\n", filename);
return -1;
}
while (1) {
printf("Input CMD:");
ret = scanf("%d", &cmd);
if (ret != 1) { /* 参数输入错误 */
/* 输入参数错误的时候会有错误的字符串卡死在缓冲区里，所以使用get */
gets(str); /* 防止卡死 */
}
if(cmd == 1) /* 关闭 LED 灯 */
cmd = CLOSE_CMD;
else if(cmd == 2) /* 打开 LED 灯 */
cmd = OPEN_CMD;
else if(cmd == 3) {
cmd = SETPERIOD_CMD; /* 设置周期值 */
printf("Input Timer Period:");
ret = scanf("%d", &arg);
if (ret != 1) { /* 参数输入错误 */
gets(str); /* 防止卡死 */
}
}
ioctl(fd, cmd, arg); /* 控制定时器的打开和关闭 */
}
close(fd);
return 0;
}
4.注意
也可以用IOW来说明要写数据，但是在驱动中，就只能用copy_from_user，里面的&arg应该以地址的形式传递。但是应用程序传递过来的就可以是地址，所以里面的arg直接就是指针，前面强制转化成（int*）就可以了
copy_from_user中的第二个参数必须是地址！
主要是给自己看的，所以肯定会出现很多错误哈哈哈哈哈
