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。
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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：
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OBJ = /home/xhy/kernelall : make -C $(OBJ) M=`pwd` modulesclean: make -C $(OBJ) M=`pwd` cleanobj-m += led_sysfs.o
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? make后把生成的led_sysfs.ko文件push到小机上，
? adb shell
? insmod led_sysfs.ko
??cd /sys/
# lsmodled_sysfs 1432 0 - Live 0xbf02a000
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? cd led_sysfs
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# cat ledstateledoff
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