Linux 驱动——Button驱动2

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button_drv.c驱动文件：

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <asm/io.h>   //包含iomap函数iounmap函数
#include <asm/uaccess.h> //包含copy_from_user函数
#include <linux/device.h> //包含类相关的处理函数
#include <asm/arch/regs-gpio.h>    //包含S3C2410_GPF0等相关的
#include <linux/irq.h>   //包含IRQ_HANDLED、IRQ_TYPE_EDGE_RISING
#include <asm-arm/irq.h> //包含IRQT_BOTHEDGE触发类型
#include <linux/interrupt.h>request_irq、free_irq函数
#include <linux/delay.h>
#include <asm/hardware.h>

#define DRIVER_NAME "button_drv"
#define DEVICE_NAME "button_dev"

int major;

volatile unsigned long *gpfcon;
volatile unsigned long *gpfdat;

volatile unsigned long *gpgcon;
volatile unsigned long *gpgdat;

struct class *buttondrv_class;
struct class_device *buttondrv_class_device;

unsigned int key_val;
unsigned int ev_press = 0;
DECLARE_WAIT_QUEUE_HEAD(button_waitq); //注册等待队列button_waitq

struct pin_desc{
unsigned int pin;
unsigned int key_val;
};

struct pin_desc pins_desc[4] = {
{S3C2410_GPF0, 0x01},
{S3C2410_GPF2, 0x02},
{S3C2410_GPG3, 0x03},
{S3C2410_GPG11, 0x04},
};

irqreturn_t buttons_irq(int irq, void *dev_id)//按键中断服务函数
{
unsigned int pin_val;
struct pin_desc *pin_desc = (struct pin_desc *)dev_id;

pin_val = s3c2410_gpio_getpin(pin_desc->pin);

if(pin_val)
{
key_val = 0x80 | pin_desc->key_val;
}
else
{
key_val = pin_desc->key_val;
}
wake_up_interruptible(&button_waitq);//唤醒休眠的进程, 即调用read函数的进程
ev_press = 1;
return IRQ_HANDLED;
}

int button_drv_open(struct inode *inode, struct file *file)
{
int ret;
ret = request_irq(IRQ_EINT0, buttons_irq, IRQT_BOTHEDGE, "S1", (void*)&pins_desc[0]); //注册一个外部中断S1, 双边沿触发

//dev_id为&pins_desc[0]

if(ret)
{
printk("open failed 1 \n");
return -1;
}
ret = request_irq(IRQ_EINT2, buttons_irq, IRQT_BOTHEDGE, "S2", (void*)&pins_desc[1]);
if(ret)
{
printk("open failed 2 \n");
return -1;
}
ret = request_irq(IRQ_EINT11, buttons_irq, IRQT_BOTHEDGE, "S3", (void*)&pins_desc[2]);
if(ret)
{
printk("open fail 3 \n");
return -1;
}
ret = request_irq(IRQ_EINT19, buttons_irq, IRQT_BOTHEDGE, "S4", (void*)&pins_desc[3]);
if(ret)
{
printk("open fail 4 \n");
return -1;
}
return 0;
}

ssize_t button_drv_read(struct file *file, char __user *userbuf, size_t count, loff_t *off)
{
int ret;

wait_event_interruptible(button_waitq, ev_press);//上层应用调用read函数时, ev_press为0, 就将button_waitq加入等待队列, 并释放cpu进入睡眠状态

//当有按键按下时, 中断处理函数唤醒休眠进程，将ev_press置为1，当上层应用再次调用read函数时

//就会不进入睡眠状态而直接读取按键值
ret = copy_to_user(userbuf, &key_val, 1);//将取得的键值传递给上层应用
if(ret)
{
printk("copy eror \n");
return -1;
}
ev_press = 0; //按键值读取后再次将ev_press置0, 这样上层再次调用时就又会进入睡眠，直到中断再次唤醒
return 1;
}

int button_drv_close(struct inode *inode, struct file *file)
{
free_irq(IRQ_EINT0, (void*)&pins_desc[0]);//释放中断, 根据IRQEINT0找到irq_desc结构, 根据pins_desc[0]找到irq_desc->action结构
free_irq(IRQ_EINT2, (void*)&pins_desc[1]);
free_irq(IRQ_EINT11, (void*)&pins_desc[2]);
free_irq(IRQ_EINT19, (void*)&pins_desc[3]);
return 0;
}

struct file_operations button_drv_fops = {
.owner = THIS_MODULE,
.open = button_drv_open,
.read = button_drv_read,
.release = button_drv_close,
};

int __init button_drv_init(void)
{
major = register_chrdev(0, DRIVER_NAME, &button_drv_fops);
if(major<0)
{
printk("fail 1 button_drv \n");
}

buttondrv_class = class_create(THIS_MODULE, DEVICE_NAME);
if(buttondrv_class<0)
{
printk("fail 2 button_dev \n");
}
buttondrv_class_device = class_device_create(buttondrv_class, NULL, MKDEV(major,0), NULL, DEVICE_NAME);
if(buttondrv_class_device<0)
{
printk("fail 3 button_dev \n");
}

gpfcon = (volatile unsigned long *)ioremap(0x56000050, 16);
gpfdat = gpfcon + 1;
gpgcon = (volatile unsigned long *)ioremap(0x56000060, 16);
gpgdat = gpgcon + 1;
return 0;
}

void __exit button_drv_exit(void)
{
unregister_chrdev(major, DEVICE_NAME);
class_device_unregister(buttondrv_class_device);
class_destroy(buttondrv_class);
iounmap(gpfcon);
iounmap(gpgcon);
}

module_init(button_drv_init);
module_exit(button_drv_exit);

MODULE_LICENSE("GPL");

Makefile文件：

obj-m += button_drv.o

KERN_DIR = /work/system/linux-2.6.22.6

all:
make -C $(KERN_DIR) M=`pwd` modules
clean:
rm -rf *.o *.ko *.order *.symvers *.mod.c

button_app.c文件：

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>

int main(int argc, char **argv)
{
int fd;
char *filename;
unsigned char keyVal;

filename = argv[1];

fd = open(filename, O_RDWR);
if(fd<0)
{
printf("can not open \n");
}

while(1)
{
read(fd, &keyVal, 1);
printf("keyVal: %x \n",keyVal);
}