字符设备驱动程序按键驱动---中断方式
中断函数：包含#include<linux/irq.h>
request_irq(irq,handle,irqflag,name,dev_id)
{
1,分配一个irqaction结构体
2、把这个结构体放到irq_desc[irq]（action链表）中
3、设置引脚
4、使能中断
}
free_irq(irq,dev_id)
{
1、irqaciton出链
2、禁止中断
}
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1、open函数里，配置中断引脚，中断方式irqflags,中断号irq(如外部中断,用于表明哪个引脚)，处理函数handle，中断名name,设备号dev_id
调用request_irq(irq,handle,irqflag,name,dev_id)
static int third_drv_open(struct inode *inode, struct file *file)
{
/* 配置GPF0,2为输入引脚 */
/* 配置GPG3,11为输入引脚 */
request_irq(IRQ_EINT0, buttons_irq, IRQT_BOTHEDGE, "S2", &pins_desc[0]);
request_irq(IRQ_EINT2, buttons_irq, IRQT_BOTHEDGE, "S3", &pins_desc[1]);
request_irq(IRQ_EINT11, buttons_irq, IRQT_BOTHEDGE, "S4", &pins_desc[2]);
request_irq(IRQ_EINT19, buttons_irq, IRQT_BOTHEDGE, "S5", &pins_desc[3]);
return 0;
}
2、在file_operation结构体添加
.release = third_drv_close,
用于关闭中断函数
int third_drv_close(struct inode *inode, struct file *file)
{
free_irq(IRQ_EINT0, &pins_desc[0]);
free_irq(IRQ_EINT2, &pins_desc[1]);
free_irq(IRQ_EINT11, &pins_desc[2]);
free_irq(IRQ_EINT19, &pins_desc[3]);
return 0;
}
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中断处理函数Button_irq对中断发生时需要处理的事件，本次主要时对按键中断函数处理
/* 键值: 按下时, 0x01, 0x02, 0x03, 0x04 */
/* 键值: 松开时, 0x81, 0x82, 0x83, 0x84 */
static unsigned char key_val;
struct pin_desc pins_desc[4] = {
{S3C2410_GPF0, 0x01},
{S3C2410_GPF2, 0x02},
{S3C2410_GPG3, 0x03},
{S3C2410_GPG11, 0x04},
};
/*
* 确定按键值
*/
static irqreturn_t buttons_irq(int irq, void *dev_id)
{
/* 引脚描述结构体 */
struct pin_desc * pindesc = (struct pin_desc *)dev_id;
unsigned int pinval;
/* 系统函数读出引脚值 */
pinval = s3c2410_gpio_getpin(pindesc->pin);
if (pinval)
{
/* 松开 */
key_val = 0x80 | pindesc->key_val;
}
else
{
/* 按下 */
key_val = pindesc->key_val;
}
ev_press = 1; /* 表示中断发生了 */
wake_up_interruptible(&button_waitq); /* 唤醒休眠的进程 */
return IRQ_RETVAL(IRQ_HANDLED);
}
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读函数需要处理的事件
1、判断按键发生事件 ，没有就休眠，让出CPU
2、有按键事件发生，返回按键值
/* 中断事件标志, 中断服务程序将它置1，third_drv_read将它清0 */
static volatile int ev_press = 0;
struct pin_desc{
unsigned int pin;
unsigned int key_val;
};
ssize_t third_drv_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
{
if (size != 1)
return -EINVAL;
/* 如果没有按键动作, 休眠 */
wait_event_interruptible(button_waitq, ev_press);
/* 如果有按键动作, 返回键值 */
copy_to_user(buf, &key_val, 1);
ev_press = 0;
return 1;
}
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相关按键中断驱动代码：
third_drv.c
#include <linux/module.h> #include <linux/kernel.h> #include <linux/fs.h> #include <linux/init.h> #include <linux/delay.h> #include <linux/irq.h> #include <asm/uaccess.h> #include <asm/irq.h> #include <asm/io.h> #include <asm/arch/regs-gpio.h> #include <asm/hardware.h> static struct class *thirddrv_class; static struct class_device *thirddrv_class_dev; volatile unsigned long *gpfcon; volatile unsigned long *gpfdat; volatile unsigned long *gpgcon; volatile unsigned long *gpgdat; static DECLARE_WAIT_QUEUE_HEAD(button_waitq); /* 中断事件标志, 中断服务程序将它置1，third_drv_read将它清0 */ static volatile int ev_press = 0; struct pin_desc{ unsigned int pin; unsigned int key_val; }; /* 键值: 按下时, 0x01, 0x02, 0x03, 0x04 */ /* 键值: 松开时, 0x81, 0x82, 0x83, 0x84 */ static unsigned char key_val; struct pin_desc pins_desc[4] = { {S3C2410_GPF0, 0x01}, {S3C2410_GPF2, 0x02}, {S3C2410_GPG3, 0x03}, {S3C2410_GPG11, 0x04}, }; /* * 确定按键值 */ static irqreturn_t buttons_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) { /* 松开 */ key_val = 0x80 | pindesc->key_val; } else { /* 按下 */ key_val = pindesc->key_val; } ev_press = 1; /* 表示中断发生了 */ wake_up_interruptible(&button_waitq); /* 唤醒休眠的进程 */ return IRQ_RETVAL(IRQ_HANDLED); } static int third_drv_open(struct inode *inode, struct file *file) { /* 配置GPF0,2为输入引脚 */ /* 配置GPG3,11为输入引脚 */ request_irq(IRQ_EINT0, buttons_irq, IRQT_BOTHEDGE, "S2", &pins_desc[0]); request_irq(IRQ_EINT2, buttons_irq, IRQT_BOTHEDGE, "S3", &pins_desc[1]); request_irq(IRQ_EINT11, buttons_irq, IRQT_BOTHEDGE, "S4", &pins_desc[2]); request_irq(IRQ_EINT19, buttons_irq, IRQT_BOTHEDGE, "S5", &pins_desc[3]); return 0; } ssize_t third_drv_read(struct file *file, char __user *buf, size_t size, loff_t *ppos) { if (size != 1) return -EINVAL; /* 如果没有按键动作, 休眠 */ wait_event_interruptible(button_waitq, ev_press); /* 如果有按键动作, 返回键值 */ copy_to_user(buf, &key_val, 1); ev_press = 0; return 1; } int third_drv_close(struct inode *inode, struct file *file) { free_irq(IRQ_EINT0, &pins_desc[0]); free_irq(IRQ_EINT2, &pins_desc[1]); free_irq(IRQ_EINT11, &pins_desc[2]); free_irq(IRQ_EINT19, &pins_desc[3]); return 0; } static struct file_operations sencod_drv_fops = { .owner = THIS_MODULE, /* 这是一个宏，推向编译模块时自动创建的__this_module变量 */ .open = third_drv_open, .read = third_drv_read, .release = third_drv_close, }; int major; static int third_drv_init(void) { major = register_chrdev(0, "third_drv", &sencod_drv_fops); thirddrv_class = class_create(THIS_MODULE, "third_drv"); thirddrv_class_dev = class_device_create(thirddrv_class, NULL, MKDEV(major, 0), NULL, "buttons"); /* /dev/buttons */ gpfcon = (volatile unsigned long *)ioremap(0x56000050, 16); gpfdat = gpfcon + 1; gpgcon = (volatile unsigned long *)ioremap(0x56000060, 16); gpgdat = gpgcon + 1; return 0; } static void third_drv_exit(void) { unregister_chrdev(major, "third_drv"); class_device_unregister(thirddrv_class_dev); class_destroy(thirddrv_class); iounmap(gpfcon); iounmap(gpgcon); return 0; } module_init(third_drv_init); module_exit(third_drv_exit); MODULE_LICENSE("GPL");
Makefile
KERN_DIR = /work/system/linux-2.6.22.6 all: make -C $(KERN_DIR) M=`pwd` modules clean: make -C $(KERN_DIR) M=`pwd` modules clean rm -rf modules.order obj-m += third_drv.o
thirddrvtest.c
#include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <stdio.h> /* thirddrvtest */ int main(int argc, char **argv) { int fd; unsigned char key_val; fd = open("/dev/buttons", O_RDWR); if (fd < 0) { printf("can't open!\n"); } while (1) { read(fd, &key_val, 1); printf("key_val = 0x%x\n", key_val); } return 0; }
