TQ2440按键驱动实现方法1--混杂设备

利用混杂设备实现按键驱动
1.TQ2440按键资源
     k1  --  GPF1 -- EINT1
     k2  --  GPF4 -- EINT4
     k3  --  GPF2 -- EINT2
     k4  --  GPF0 -- EINT0
2.内核介绍
    本驱动基于linux-2.6.32.67内核
3.混杂设备介绍
    linux中特殊的一类字符设备，他们共享一个主设备号（10），但是次设备号不同，其设备文件自动创建。结构如下：   

struct miscdevice {
    int minor;
    const char *name;
    const struct file_operations *fops;
    struct list_head list;
    struct device *parent;
    struct device *this_device;
    const char *nodename;
    mode_t mode;
};

4.按键驱动程序（基于混杂设备实现）
   misc_button.c

#include "linux/module.h"
#include "linux/types.h"
#include "linux/fs.h"
#include "linux/platform_device.h"
#include "mach/regs-gpio.h"
#include "mach/irqs.h"
#include "mach/gpio-fns.h"
#include "linux/interrupt.h"
#include "linux/device.h"
#include "linux/io.h"
#include "linux/miscdevice.h"
#include "linux/clk.h"
#include "linux/uaccess.h"
#include "linux/sched.h"
#include "linux/poll.h"
#include "linux/unistd.h"
#include "linux/irq.h"

static DECLARE_WAIT_QUEUE_HEAD(button_waitq);
static volatile int ev_press=0;
static volatile char key_value[]={'0','0','0','0'};

struct button_irq_desc{
  int irq;
  int pin;
  int pin_setting;
  int number;
  char *name;
};

static struct button_irq_desc button_irqs[]={
  {IRQ_EINT1,S3C2410_GPF(1),S3C2410_GPF1_EINT1,0,"key1"},
  {IRQ_EINT4,S3C2410_GPF(4),S3C2410_GPF4_EINT4,1,"key2"},
  {IRQ_EINT2,S3C2410_GPF(2),S3C2410_GPF2_EINT2,2,"key3"},
  {IRQ_EINT0,S3C2410_GPF(0),S3C2410_GPF0_EINT0,3,"key4"},
};

//isr
static irqreturn_t buttons_isr(int irq,void *dev_id){
  int down;
  struct button_irq_desc *pirqs=(struct button_irq_desc*)dev_id;

  down=!s3c2410_gpio_getpin(pirqs->pin);

  if(down!=(key_value[pirqs->number]&1)){
    key_value[pirqs->number]='0'+down;
    ev_press=1;
    wake_up_interruptible(&button_waitq);
  }
  return IRQ_RETVAL(IRQ_HANDLED);
}

//misc opt
static int s3c2440_buttons_open(struct inode *inode,struct file *file){
  int i;
  int err=0;

  for(i=0;i<sizeof(button_irqs)/sizeof(button_irqs[0]);i++){
    if(button_irqs[i].irq<0){
      continue;
    }

    err=request_irq(button_irqs[i].irq,buttons_isr,IRQ_TYPE_EDGE_BOTH,button_irqs[i].name,(void*)&button_irqs[i]);
    if(err)
      break;
  }

  if(err){
    i--;
    for(;i>=0;i--){
      if(button_irqs[i].irq<0)
        continue;
      disable_irq(button_irqs[i].irq);
      free_irq(button_irqs[i].irq,(void*)&button_irqs[i]);
    }
    return -EBUSY;
  }

  ev_press=0;
  return 0;
}
static int s3c2440_buttons_close(struct inode *inode,struct file *file){
  int i;
  for(i=0;i<sizeof(button_irqs)/sizeof(button_irqs[0]);i++){
    if(button_irqs[i].irq<0)
      continue;
    free_irq(button_irqs[i].irq,(void*)&button_irqs);
  }
  return 0;
}
static int s3c2440_buttons_read(struct file *filp,char __user *buff,size_t count,loff_t *offp){
  unsigned long err;
  if(!ev_press){
    if(filp->f_flags&O_NONBLOCK)
      return -EAGAIN;
    else
      wait_event_interruptible(button_waitq,ev_press);
  }
  ev_press=0;
  err=copy_to_user(buff,&key_value,sizeof(key_value));
  return sizeof(key_value);
}
//misc ops
static struct file_operations s3c2440_buttons_fops={
  .owner=THIS_MODULE,
  .open=s3c2440_buttons_open,
  .release=s3c2440_buttons_close,
  .read=s3c2440_buttons_read,
};

//misc
static struct miscdevice s3c2440_miscdev={
  .minor=MISC_DYNAMIC_MINOR,
  .name="buttons-test",
  .fops=&s3c2440_buttons_fops,
};

static int dev_init(void){
  int ret;
  ret=misc_register(&s3c2440_miscdev);
  printk("misc dev init.\n");
  return ret;
}

static void dev_exit(void){
  misc_deregister(&s3c2440_miscdev);
}

module_init(dev_init);
module_exit(dev_exit);

MODULE_LICENSE("GPL");

5.测试程序
  根据驱动的实现方法，实现测试程序如下：
  button_test.c

#include "stdio.h"
#include "string.h"
#include "stdlib.h"
#include "unistd.h"
#include "sys/ioctl.h"
#include "sys/types.h"
#include "sys/stat.h"
#include "fcntl.h"
#include "sys/select.h"
#include "sys/time.h"
#include "errno.h"


int main(void){
  int buttons_fd;
  char key_value[4];
  char first=1;
  int i;

  buttons_fd=open("/dev/buttons-test",0);
  if(buttons_fd<0){
    perror("open device buttons.\n");
    exit(1);
  }

  for(;;){
    char key_value_temp[4];
    int ret;
    ret=read(buttons_fd,key_value_temp,sizeof(key_value_temp));
    if(ret!=sizeof(key_value_temp)){
      perror("read button.");
      exit(1);
    }
    for(i=0;i<sizeof(key_value);i++){
      if(key_value[i]!=key_value_temp[i]){
        key_value[i]=key_value_temp[i];
        printf("k%d is %s%s",i+1,key_value[i]=='0'?"up":"down",first?",":"");
      }
    }
    first=0;
    if(first==0){
      printf("\n");
    }

  }
  close(buttons_fd);
  return 0;
}

6.编译，下载
   分别编译内核模块和测试程序，分别生成misc_button.ko和button_test，通过nfs方式下载到TQ2440开发板中。运行结果如下：