嵌入式Linux驱动学习之路(十四)按键驱动-同步、互斥、阻塞

时间:2023-02-05 18:19:55

目的:同一个时刻,只能有一个应用程序打开我们的驱动程序。

①原子操作:

v = ATOMIC_INIT( i )   定义原子变量v并初始化为i

atomic_read(v)        返回原子变量的值
atomic_set(v,i)        设置原子变量的值

atomic_inc_and_test(v)     自加后和测试是否为0  为0则返回true

atomic_dec_and_test(v)     自减后和测试是否为0  为0则返回true

atomic_inc(v)      自加
#atomic_dec(v)     自减

驱动代码:

#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/spinlock.h>
#include <linux/errno.h>
#include <linux/random.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/wait.h>
#include <linux/mutex.h>
#include <linux/io.h>
#include <asm/irq.h>
#include <linux/irq.h>
#include <linux/fs.h>
#include <asm/arch/regs-gpio.h>
#include <linux/interrupt.h>
#include <linux/poll.h> static struct class *key_class; //创建类
static struct class_device *key_class_devs; //创建类对应的设备 struct pin_desc{
unsigned int pin;
unsigned int key_val;
};
struct pin_desc pins_desc[] = {
{S3C2410_GPF0,0X01},
{S3C2410_GPF2,0X02},
{S3C2410_GPG3,0X03},
{S3C2410_GPG11,0X04},
};
unsigned char keyvals=; static volatile int ev_press = ;
static DECLARE_WAIT_QUEUE_HEAD(button_waitq); static struct fasync_struct *key_async_queue; atomic_t canopen = ATOMIC_INIT(); static irqreturn_t keys_irq(int irq, void *dev_id)
{
struct pin_desc *pindesc = (struct pin_desc *)dev_id;
unsigned int pinval;
pinval = s3c2410_gpio_getpin(pindesc->pin);
if(pinval)
{
keyvals = pindesc->key_val|0x80;
}
else
{
keyvals = pindesc->key_val;
}
ev_press = ;
wake_up_interruptible(&button_waitq); kill_fasync (&key_async_queue, SIGIO, POLL_IN); return IRQ_HANDLED;
} int key_open(struct inode *inode, struct file *fp)
{
if(!atomic_dec_and_test(&canopen)) //if --canopen==0 return ture /*自减后和0相比 如果等于0 则返回true*/
{
atomic_inc(&canopen);
return -EBUSY;
} request_irq( IRQ_EINT0, keys_irq, IRQT_BOTHEDGE, "key2", &pins_desc[]);
request_irq( IRQ_EINT2, keys_irq, IRQT_BOTHEDGE, "key3", &pins_desc[]);
request_irq( IRQ_EINT11, keys_irq, IRQT_BOTHEDGE, "key4", &pins_desc[]);
request_irq( IRQ_EINT19, keys_irq, IRQT_BOTHEDGE, "key5", &pins_desc[]);
return ;
} ssize_t key_read(struct file *fp, char __user *buff, size_t count, loff_t *offp){ if(count != )
{
return -EINVAL;
}
wait_event_interruptible(button_waitq,ev_press); copy_to_user(buff,&keyvals,);
ev_press = ;
return ;
} ssize_t key_write(struct file *fp, const char __user *buf, size_t count, loff_t *ppos){
} int key_close(struct inode *inode, struct file *file)
{
atomic_inc(&canopen);
free_irq(IRQ_EINT0,&pins_desc[]);
free_irq(IRQ_EINT2,&pins_desc[]);
free_irq(IRQ_EINT11,&pins_desc[]);
free_irq(IRQ_EINT19,&pins_desc[]);
} static unsigned int key_poll(struct file *file, struct poll_table_struct *wait)
{
unsigned int mask = ;
poll_wait(file, &button_waitq,wait);
if(ev_press)
mask |= POLLIN|POLLRDNORM;
return mask;
} static int key_fsync (int fd, struct file *filp, int on)
{
printk("ok\n");
return fasync_helper (fd, filp, on, &key_async_queue);
} struct file_operations led_fops={
.owner = THIS_MODULE,
.open = key_open,
.write = key_write,
.read = key_read,
.release = key_close,
.poll = key_poll,
.fasync = key_fsync,
}; int major;
static int key_init(void)
{
major = register_chrdev( ,"key_drv", &led_fops );
key_class = class_create(THIS_MODULE,"key_class");
key_class_devs = class_device_create(key_class,NULL,MKDEV(major,),NULL,"my_keys"); printk("key install Module\n");
return ;
} static void key_exit(void)
{
unregister_chrdev( major, "key_drv" );
class_device_unregister(key_class_devs);
class_destroy(key_class);
printk("key Module exit\n");
} module_init(key_init);
module_exit(key_exit);
MODULE_LICENSE("GPL");

信号量:

#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/spinlock.h>
#include <linux/errno.h>
#include <linux/random.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/wait.h>
#include <linux/mutex.h>
#include <linux/io.h>
#include <asm/irq.h>
#include <linux/irq.h>
#include <linux/fs.h>
#include <asm/arch/regs-gpio.h>
#include <linux/interrupt.h>
#include <linux/poll.h> static struct class *key_class; //创建类
static struct class_device *key_class_devs; //创建类对应的设备 struct pin_desc{
unsigned int pin;
unsigned int key_val;
};
struct pin_desc pins_desc[] = {
{S3C2410_GPF0,0X01},
{S3C2410_GPF2,0X02},
{S3C2410_GPG3,0X03},
{S3C2410_GPG11,0X04},
};
unsigned char keyvals=; static volatile int ev_press = ;
static DECLARE_WAIT_QUEUE_HEAD(button_waitq); static struct fasync_struct *key_async_queue; static DECLARE_MUTEX(canopen); //定义互斥锁 static irqreturn_t keys_irq(int irq, void *dev_id)
{
struct pin_desc *pindesc = (struct pin_desc *)dev_id;
unsigned int pinval;
pinval = s3c2410_gpio_getpin(pindesc->pin);
if(pinval)
{
keyvals = pindesc->key_val|0x80;
}
else
{
keyvals = pindesc->key_val;
}
ev_press = ;
wake_up_interruptible(&button_waitq); kill_fasync (&key_async_queue, SIGIO, POLL_IN); return IRQ_HANDLED;
} int key_open(struct inode *inode, struct file *fp)
{
/*获取信号量*/
down(&canopen);      //如果设备已经被打开,那么程序将会一直停在这里知道信号量被释放。 request_irq( IRQ_EINT0, keys_irq, IRQT_BOTHEDGE, "key2", &pins_desc[]);
request_irq( IRQ_EINT2, keys_irq, IRQT_BOTHEDGE, "key3", &pins_desc[]);
request_irq( IRQ_EINT11, keys_irq, IRQT_BOTHEDGE, "key4", &pins_desc[]);
request_irq( IRQ_EINT19, keys_irq, IRQT_BOTHEDGE, "key5", &pins_desc[]);
return ;
} ssize_t key_read(struct file *fp, char __user *buff, size_t count, loff_t *offp){ if(count != )
{
return -EINVAL;
}
wait_event_interruptible(button_waitq,ev_press); copy_to_user(buff,&keyvals,);
ev_press = ;
return ;
} ssize_t key_write(struct file *fp, const char __user *buf, size_t count, loff_t *ppos){
} int key_close(struct inode *inode, struct file *file)
{
free_irq(IRQ_EINT0,&pins_desc[]);
free_irq(IRQ_EINT2,&pins_desc[]);
free_irq(IRQ_EINT11,&pins_desc[]);
free_irq(IRQ_EINT19,&pins_desc[]);
up(&canopen);
} static unsigned int key_poll(struct file *file, struct poll_table_struct *wait)
{
unsigned int mask = ;
poll_wait(file, &button_waitq,wait);
if(ev_press)
mask |= POLLIN|POLLRDNORM;
return mask;
} static int key_fsync (int fd, struct file *filp, int on)
{
printk("ok\n");
return fasync_helper (fd, filp, on, &key_async_queue);
} struct file_operations led_fops={
.owner = THIS_MODULE,
.open = key_open,
.write = key_write,
.read = key_read,
.release = key_close,
.poll = key_poll,
.fasync = key_fsync,
}; int major;
static int key_init(void)
{
major = register_chrdev( ,"key_drv", &led_fops );
key_class = class_create(THIS_MODULE,"key_class");
key_class_devs = class_device_create(key_class,NULL,MKDEV(major,),NULL,"my_keys"); printk("key install Module\n");
return ;
} static void key_exit(void)
{
unregister_chrdev( major, "key_drv" );
class_device_unregister(key_class_devs);
class_destroy(key_class);
printk("key Module exit\n");
} module_init(key_init);
module_exit(key_exit);
MODULE_LICENSE("GPL");

阻塞:分为阻塞和非阻塞

  如何分辨阻塞和非阻塞呢?则需要在打开设备文件的时候传入一个参数

#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/spinlock.h>
#include <linux/errno.h>
#include <linux/random.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/wait.h>
#include <linux/mutex.h>
#include <linux/io.h>
#include <asm/irq.h>
#include <linux/irq.h>
#include <linux/fs.h>
#include <asm/arch/regs-gpio.h>
#include <linux/interrupt.h>
#include <linux/poll.h> static struct class *key_class; //创建类
static struct class_device *key_class_devs; //创建类对应的设备 struct pin_desc{
unsigned int pin;
unsigned int key_val;
};
struct pin_desc pins_desc[] = {
{S3C2410_GPF0,0X01},
{S3C2410_GPF2,0X02},
{S3C2410_GPG3,0X03},
{S3C2410_GPG11,0X04},
};
unsigned char keyvals=; static volatile int ev_press = ;
static DECLARE_WAIT_QUEUE_HEAD(button_waitq); static struct fasync_struct *key_async_queue; static DECLARE_MUTEX(canopen); //定义互斥锁 static irqreturn_t keys_irq(int irq, void *dev_id)
{
struct pin_desc *pindesc = (struct pin_desc *)dev_id;
unsigned int pinval;
pinval = s3c2410_gpio_getpin(pindesc->pin);
if(pinval)
{
keyvals = pindesc->key_val|0x80;
}
else
{
keyvals = pindesc->key_val;
}
ev_press = ;
wake_up_interruptible(&button_waitq); kill_fasync (&key_async_queue, SIGIO, POLL_IN); return IRQ_HANDLED;
} int key_open(struct inode *inode, struct file *fp)
{
/*获取信号量*/
if( fp->f_flags & O_NONBLOCK )
{
if(down_trylock(&canopen))
return -EBUSY;
}
else
{
down(&canopen);
}
request_irq( IRQ_EINT0, keys_irq, IRQT_BOTHEDGE, "key2", &pins_desc[]);
request_irq( IRQ_EINT2, keys_irq, IRQT_BOTHEDGE, "key3", &pins_desc[]);
request_irq( IRQ_EINT11, keys_irq, IRQT_BOTHEDGE, "key4", &pins_desc[]);
request_irq( IRQ_EINT19, keys_irq, IRQT_BOTHEDGE, "key5", &pins_desc[]);
return ;
} ssize_t key_read(struct file *fp, char __user *buff, size_t count, loff_t *offp){ if(fp->f_flags & O_NONBLOCK )
{
if(!ev_press)
return -EAGAIN;
}
else
{
wait_event_interruptible(button_waitq,ev_press);
}
if(count != )
{
return -EINVAL;
} copy_to_user(buff,&keyvals,);
ev_press = ;
return ;
} ssize_t key_write(struct file *fp, const char __user *buf, size_t count, loff_t *ppos){
} int key_close(struct inode *inode, struct file *file)
{
free_irq(IRQ_EINT0,&pins_desc[]);
free_irq(IRQ_EINT2,&pins_desc[]);
free_irq(IRQ_EINT11,&pins_desc[]);
free_irq(IRQ_EINT19,&pins_desc[]);
up(&canopen);
} static unsigned int key_poll(struct file *file, struct poll_table_struct *wait)
{
unsigned int mask = ;
poll_wait(file, &button_waitq,wait);
if(ev_press)
mask |= POLLIN|POLLRDNORM;
return mask;
} static int key_fsync (int fd, struct file *filp, int on)
{
printk("ok\n");
return fasync_helper (fd, filp, on, &key_async_queue);
} struct file_operations led_fops={
.owner = THIS_MODULE,
.open = key_open,
.write = key_write,
.read = key_read,
.release = key_close,
.poll = key_poll,
.fasync = key_fsync,
}; int major;
static int key_init(void)
{
major = register_chrdev( ,"key_drv", &led_fops );
key_class = class_create(THIS_MODULE,"key_class");
key_class_devs = class_device_create(key_class,NULL,MKDEV(major,),NULL,"my_keys"); printk("key install Module\n");
return ;
} static void key_exit(void)
{
unregister_chrdev( major, "key_drv" );
class_device_unregister(key_class_devs);
class_destroy(key_class);
printk("key Module exit\n");
} module_init(key_init);
module_exit(key_exit);
MODULE_LICENSE("GPL");

阻塞测试文件:

#include <stdio.h>
#include <signal.h>
#include <fcntl.h>
#include <unistd.h> int fd; static char key_val;
int main( int argc, char **argv )
{
int oflags;
fd = open("/dev/my_keys",O_RDWR|O_NONBLOCK);  /* O_NONBLOCK为非阻塞*/ if(fd<)
{
printf("open failed\n");
return ;
} while()
{
read(fd,&key_val,);
printf("key_val:%d\n",key_val);
sleep();
} return ;
}

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