设备模型五(实例代码)

• 前言
  这篇主要是对前四章的总结
  本例子参考<<深入linux设备驱动内核机制>>
  例子真好, 我在此之上又添加了一些

#include <linux/init.h>#include <linux/module.h>#include <linux/kernel.h>#include <linux/kobject.h>#include <linux/sysfs.h>#include <linux/slab.h>static struct kobject * parent;static struct kobject * child;static struct kset *c_kset;static unsigned long flag = 1;static unsigned long xx = 1;static ssize_t att_show(struct kobject *kobj, struct attribute *attr, char *buf){    size_t count = 0;    count += sprintf(&buf[count], "%lu\n", flag);    return count;}static ssize_t att_store(struct kobject *kobj, struct attribute *attr, const char* buf, size_t count){    flag = buf[0] - '0';    switch(flag)    {        case 0:            printk(KERN_ALERT "ADD===============\n");            //消息发不出去            kobj->uevent_suppress = 1;            kobject_uevent(kobj, KOBJ_ADD);            break;        case 1:            printk(KERN_ALERT "REMOVE===============\n");            //消息可以发出去            kobj->uevent_suppress = 0;            kobject_uevent(kobj, KOBJ_REMOVE);            break;        case 2:            printk(KERN_ALERT "CHANGE===============\n");            xx = 1;            kobject_uevent(kobj, KOBJ_CHANGE);            break;        case 3:            xx = 0;            printk(KERN_ALERT "MOVE===============\n");            kobject_uevent(kobj, KOBJ_MOVE);            break;        case 4:            printk(KERN_ALERT "ONLINE===============\n");            kobject_uevent(kobj, KOBJ_ONLINE);            break;        case 5:            printk(KERN_ALERT "OFFLINE===============\n");            kobject_uevent(kobj, KOBJ_OFFLINE);            break;    }    return count;}static struct attribute cld_att={    .name = "cldatt",    .mode = S_IRUGO | S_IWUSR,};static const struct sysfs_ops att_ops={    .show = att_show,    .store = att_store,};static struct kobj_type cld_ktype={    .sysfs_ops = &att_ops,};static int ma_ok_uevent(struct kset *kset, struct kobject *kobj,               struct kobj_uevent_env *env){    add_uevent_var(env, "autor_name=%s", "mxg......");    add_uevent_var(env, "shi[%s]", "dashen");    return 0;}static int uevent_filter(struct kset *kset, struct kobject *kobj){    struct kobj_type *ktype = get_ktype(kobj);//过滤机制，kobject_uevent发送消息调用c_kset的.filter确定是不是cld_obj发的//通过ktype的对比,比如前一篇的说明中,如果有xx其kset也是c_kset, xx的kobj调用kobject_uevent，调用c_kset的.filter判断不是xx的ktype类型,    if (ktype == &cld_ktype)        return xx;    return 0;}static const struct kset_uevent_ops ma_uevent = {    .uevent = ma_ok_uevent,    .filter = uevent_filter,};static int kobj_demo_init(void){    int err;    parent = kobject_create_and_add("pa_obj", NULL);    child = kzalloc(sizeof(*child), GFP_KERNEL);    if(!child)        return -1;    c_kset = kset_create_and_add("c_kset", &ma_uevent, parent);    if(!c_kset)        return -1;    child->kset=c_kset;    err = kobject_init_and_add(child, &cld_ktype, parent, "cld_obj");    if(err)        return err;    err = sysfs_create_file(child, &cld_att);    return err;}static void  kobj_demo_exit(void){    sysfs_remove_file(child, &cld_att);    kset_unregister(c_kset);    kobject_del(child);    kobject_del(parent);}MODULE_LICENSE("GPL");module_init(kobj_demo_init);module_exit(kobj_demo_exit);

代码所对应的关系如下图