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 <linux/module.h>
#include <asm/uaccess.h>
#include <linux/version.h>
#include <linux/io.h>
#include <linux/gpio.h>
#include <plat/gpio-cfg.h>
#include <mach/regs-gpio.h>
#include <asm/mach/arch.h>
#include <linux/kobject.h>
#include <linux/string.h>

#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