2022年10月14日 | mini2440 简单按键中断模式驱动程序

Makefile

KERN_DIR = /home/grh/kernel_source_code/linux-2.6.32.2

all : 

make -C $(KERN_DIR) M=`pwd` modules

arm-linux-gcc key_interrupt_app.c -o key_interrupt_app

clean :

make -C $(KERN_DIR) M=`pwd` modules clean

rm -rf modules.order

obj-m += key_interrupt.o

copy : 

cp key_interrupt.ko key_interrupt_app /nfs

驱动程序代码：

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#define GRH_MODULE_NAME "key_interrupt"

static int major;

static struct class *key_interrupt_class;

static struct class_device *key_interrupt_device; 

static int key_value;

//wait_event_interruptible函数需要的两个变量

static DECLARE_WAIT_QUEUE_HEAD(grh_wait_interrupt); //休眠的进程队列头

static volatile int sleep_for_interrupt; //这个变量为0的时候read函数会休眠，中断里面将其置1，read函数末尾将其设置为0

//pin_desc是对每一个按键中断的描述，不仅仅可以是整数，也可以是更复杂到的字段，这里用简单的按键值就行了

int pin_desc[6] = {

1, 2, 3, 4, 5, 6

};

//中断处理函数

static irqreturn_t grh_handle_key_eint(int irq, void *dev_id){

int *p;

p = dev_id;

//printk(KERN_EMERG"key pressed! key=%dn", *p);

key_value = *p;

//唤醒休眠的进程

sleep_for_interrupt = 1;

wake_up_interruptible(&grh_wait_interrupt);

return IRQ_HANDLED;

}

static void init_key(void){

//注册irq中断处理函数，将按键值和中断号绑定，所有清中断操作以及初始化中断相关寄存器的操作全部交给

//内核自动完成了，不再需要像裸机程序一样显式地对寄存器进行读写了，中断发生后会自动跳到grh_handle_key_eint

request_irq(IRQ_EINT8, grh_handle_key_eint, IRQ_TYPE_EDGE_BOTH, "key1", pin_desc);

request_irq(IRQ_EINT11, grh_handle_key_eint, IRQ_TYPE_EDGE_BOTH, "key2", pin_desc+1);

request_irq(IRQ_EINT13, grh_handle_key_eint, IRQ_TYPE_EDGE_BOTH, "key3", pin_desc+2);

request_irq(IRQ_EINT14, grh_handle_key_eint, IRQ_TYPE_EDGE_BOTH, "key4", pin_desc+3);

request_irq(IRQ_EINT15, grh_handle_key_eint, IRQ_TYPE_EDGE_BOTH, "key5", pin_desc+4);

request_irq(IRQ_EINT19, grh_handle_key_eint, IRQ_TYPE_EDGE_BOTH, "key6", pin_desc+5);

}

static int key_interrupt_open(struct inode *inode, struct file *file){

printk(KERN_EMERG"DRIVER: OPENn");

sleep_for_interrupt = 0;

init_key();

return 0;

}

static ssize_t key_interrupt_write(struct inode *inode, const char __user *buf, size_t count, loff_t *ppos){

printk(KERN_EMERG"DRIVER: WRITEn");

return 0;

}

static ssize_t key_interrupt_read(struct file *file, char __user *buf, size_t count, loff_t *ppos){

printk(KERN_EMERG"DRIVER: READn");

//根据sleep_for_interrupt的数值决定是否将驱动进程加进休眠队列grh_wait_interrupt中

wait_event_interruptible(grh_wait_interrupt, sleep_for_interrupt);

copy_to_user(buf, &key_value, 4);

//下一次进入read的时候继续休眠等待中断发生

sleep_for_interrupt = 0;

return 0;

}

int key_interrupt_release(struct inode *inode, struct file *file){

//注销中断

free_irq(IRQ_EINT8, pin_desc);

free_irq(IRQ_EINT11, pin_desc+1);

free_irq(IRQ_EINT13, pin_desc+2);

free_irq(IRQ_EINT14, pin_desc+3);

free_irq(IRQ_EINT15, pin_desc+4);

free_irq(IRQ_EINT19, pin_desc+5);

printk(KERN_EMERG"DRIVER: RELEASEn");

return 0;

}

static struct file_operations key_interrupt_fops = {

.owner = THIS_MODULE,

.open = key_interrupt_open,

.write = key_interrupt_write,

.read = key_interrupt_read,

.release = key_interrupt_release,

};

int key_interrupt_module_init(void){

printk(KERN_EMERG"INIT MODULE!n");

//register the driver with the device

major = register_chrdev(0, GRH_MODULE_NAME, &key_interrupt_fops);

//create my own device class

key_interrupt_class = class_create(THIS_MODULE, "key_interrupt_class");

//create my device of my own class

key_interrupt_device = device_create(key_interrupt_class, NULL, MKDEV(major,0), NULL, "key_interrupt_device");

return 0;

}

void key_interrupt_module_exit(void){

unregister_chrdev(major, GRH_MODULE_NAME);

device_unregister(key_interrupt_device);

class_destroy(key_interrupt_class);

printk(KERN_EMERG"EXIT MODULE!n");

}

module_init(key_interrupt_module_init);

module_exit(key_interrupt_module_exit);

MODULE_AUTHOR("GRH");

MODULE_VERSION("1.0");

MODULE_DESCRIPTION("KEY POLL DRIVER");

MODULE_LICENSE("GPL");

用户空间测试程序：

#include

#include

#include

#include

#include

#include

int main(void){

int fd;

int i, sum;

int key_value;

fd = open("/dev/key_interrupt_device", O_RDWR);

if(-1 == fd){

printf("open key device error!n");

return -1;

}

while(1){

read(fd, &key_value, 4);

printf("key pressed : %dn", key_value);

}

close(fd);

return 0;

}

按下按键之后的运行结果：

当没有按键按下的时候，测试程序进程在内核态处于休眠状态，这样比起轮询式的驱动而言，资源的消耗就小了太多了：