裸机中断流程
1.外部触发
2.CPU发生中断,强制跳到异常向量处
3.跳到具体函数
a.保存具体函数
b.处理具体函数
c.恢复中断现场
linux中断
ARM架构的CPU的异常向量基地址可以是0x00000000或0xffff0000这个地址并不是物理地址,是虚拟地址,需要建立物理地址与虚拟地址的映射。所谓"向量",就是一些被安放在固定位置的代码,当发生异常时,CPU会自动执行这些固定位置上的指令。ARM架构CPU的异常向量基地址可以是0x00000000,也可以是0xffff0000,linux呃逆和使用后者。
static inline int __must_check
request_irq(unsigned int irq, irq_handler_t handler, unsigned long flags,
const char *name, void *dev)
irq:中断号
handler:中断函数
flags:触发类型
name:名字
dev:设备id,主要是和irq一起结合起来确定是哪一个。可以较为随意的设置
void free_irq(unsigned int irq, void *dev_id)
wait_event_interruptible(休眠当前进程,不向下继续执行)
eg:
static DECLARE_WAIT_QUEUE_HEAD(button_waitq); //定义一个等待队列
wait_event_interruptible(button_waitq, ev_press);
wait_event_interruptible首先会判断ev_press是否为0,如果为0才会令当前进程进入休眠;否则向下继续执行。它的第一个参数button_waitq是一个等待队列,第二个参数ev_press用来表示中断是否发生,在中断服务程序中把它置为1.
wait_up_interruptible(唤醒休眠进程)
eg:
wake_up_interruptible(&button_waitq); /* 唤醒休眠的进程 */
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
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");
thirddrvtest.c
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <unistd.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);
sleep(5);
}
return 0;
}
原文:https://www.cnblogs.com/huangdengtao/p/12487440.html