android驱动学习-sysfs文件系统设备--LED(3)

目的：学习sysfs文件系统，直接在应用层使用cat 和echo命令来控制LED。

 

===============================================

驱动：

 #include
 #include
 #include
 #include
 #include
 #include
 #include
 #include
 #include
 #include

 #define GPIO_LED1  S5PV210_GPH1(3)
 struct kobject *kobj;
 const static char *str_ledon = "ledon";
 const static char *str_ledoff= "ledoff";

 static ssize_t led_show(struct kobject *kobj, struct kobj_attribute *attr,char *buf )
 {
     char *s= buf;
     int len;
     if(gpio_get_value(GPIO_LED1))
        s += sprintf(s,"%s\n",str_ledon);
     else
       s += sprintf(s,"%s\n",str_ledoff);
     if (s != buf)
         *(s-1) = '\n';

     return (s - buf);
 }
 static ssize_t led_store(struct kobject *kobj,struct kobj_attribute *attr,const char* buf, size_t n)
 {

     char *p;
     int len;
     p = memchr(buf, '\n', n);
     len = p ? p - buf : n;
     printk(KERN_INFO "%s:enter\n",__func__);

     s3c_gpio_cfgpin(GPIO_LED1,S3C_GPIO_OUTPUT  );
     s3c_gpio_setpull(GPIO_LED1,S3C_GPIO_PULL_UP );
     if(gpio_request(GPIO_LED1,"led_sysfs")> 0)
     {
         if(!strncmp(buf,str_ledon,len ))
         {
             printk(KERN_INFO "%s:1\n",__func__);
             gpio_set_value(GPIO_LED1,0);
         }
         else if(!strncmp(buf,str_ledoff,len ))
         {
             printk(KERN_INFO "%s:2\n",__func__);
             gpio_set_value(GPIO_LED1,1);
         }
     }
     else
        printk(KERN_INFO "%s:3\n",__func__);

     return len ;
 }
 //具体属性参数
 static struct kobj_attribute  kobj_attr ={
     .attr = {
         .name =  __stringify(ledstate), //把ledstate转换成字符串
         .mode = 0666, //表示此属性可读可写
      },
     .show = led_show, //对应读
     .store= led_store, //对应写

 };
 //属性数组
 static struct attribute *attr_g[] ={
     &kobj_attr.attr,
     NULL,// 必须包含NULL
 };
 //对属性数组的封装。
 static struct attribute_group grp ={
     .attrs = attr_g,
 };

 static int __init led_init(void)
 {


     kobj = kobject_create_and_add("led_sysfs",NULL);
     if(!kobj )
     {
         printk(KERN_INFO "kobject don't create \n");
         return -ENOMEM;
     }
    return  sysfs_create_group(kobj, &grp);

 }
 static void __exit led_exit(void)
 {
    printk(KERN_INFO "%s:enter\n",__func__);
    sysfs_remove_group(kobj, &grp);
    kobject_del(kobj);
 }


 module_init(led_init);
 module_exit(led_exit);
 MODULE_LICENSE("GPL");

 

Makefile：

 

 OBJ = /home/xhy/kernel

 all :
     make -C $(OBJ) M=`pwd` modules
 clean:
     make -C $(OBJ) M=`pwd` clean

 obj-m   += led_sysfs.o

 --------------------------------------------------

  make后把生成的led_sysfs.ko文件push到小机上，

  adb shell

  insmod led_sysfs.ko

  cd /sys/

 # lsmod
 led_sysfs 1432 0 - Live 0xbf02a000

 

  cd led_sysfs

 

 # cat ledstate
 ledoff