标签：
device_driver和device必须依附总线。总线、驱动、设备最终会落实为sysfs中的一个目录。kobject对应sysfs的一个目录。
attribute直接落实sysfs中的一个文件，如果attribute非常多，show/sore函数里的分支会很凌乱。解决这个问题，提供kobj——attribute：
struct
struct kobj_attribute{ struct attribute attr; ssize_t (*show)(struct kobject *kobj,struct kobj_attribute *attr, char *buf); ssize_t (*store)(struct kobject *kobj,struct kobj_attribute *attr ,const char *buf, size_t count); };
每一个attribute会对 应自己的show、store函数，这样就极大的提高了灵活性 。sysfs是通过kobject里的kobj_type->sysfs_ops来读写attribute的，那如果利用kobj_attribute中的show/store来读写attribute，就必须在kobj_type->sysfs_ops里面指定。
static ssize_t kobj_attr_show(struct kobjct *kobj, struct attribute *attr,char *buf ) { struct kobj_attribute *kattr; ssize _t ret=-EIO; kattr=container_of(attr,struct kobj_attribute,attr); if(kattr->show) ret=kattr->show(kobj,kattr,buf); return ret; }static ssize_t kobj_attr_store(struct kobject *kobj, struct attribute *attr, const char *buf, size_t count) { struct kobj_attribute *kattr; ssize_t ret = -EIO; kattr = container_of(attr, struct kobj_attribute, attr); if (kattr->store) ret = kattr->store(kobj, kattr, buf, count); return ret; } const struct sysfs_ops kobj_sysfs_ops = { .show = kobj_attr_show, .store = kobj_attr_store, }; static void dynamic_kobj_release(struct kobject *kobj) { pr_debug("kobject: (%p): %s\n", kobj, __func__); kfree(kobj); } static struct kobj_type dynamic_kobj_ktype = { .release = dynamic_kobj_release, .sysfs_ops = &kobj_sysfs_ops, };
kobj_attribute是内核提供的更加灵活的attribute方式还要使用kobject_create来创建kobject。
struct my_attributte{ struct attribute attr; ssize_t (*sbow)(struct my_kobj kobj, struct my_attribute *attr,char *buf); ssize_t(*store)(struct my_kobj *obj,struct my_attribute *attr,char *buf,size_t count); }
先创建接口：sysfs_creat_group(&xxdev->dev.kobj,&dev_attr_grp);
封装：static struct attribute_group dev_attr_grp={.attrs=dev_attrs,}
结构体：static Strut attribute *dev_attrs[]={&dev_attr_polling.attr,null,}
节点：static device_attr(polling,666,show_polling,set_polling).
读写：size_t show_polling(kobj,attribute,buf);
标签：
原文地址：http://www.cnblogs.com/xjh-2016/p/5459159.html
