设备模型4之kobject（实例）

写过vfs和sysfs之后发现网上的文章太多了，很多写的比我好多了。kobject也不例外，所以我就不再说理论知识了，接下来主要以图片和实例为主。先声明一下我的实验平台是arm920t+linux-3.2.36+busybox-1.16.1

我的kobj框架

代码

#include <linux/device.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/slab.h>

MODULE_AUTHOR("wwxxxxll");
MODULE_LICENSE("Dual BSD/GPL");

#define DEBUG_EN//debug使能开关

#define PRINT_COLOR_RESET     "\33[0m"
#define PRINT_COLOR_BLACK     "\33[30m"
#define PRINT_COLOR_RED       "\33[31m"
#define PRINT_COLOR_GREEN     "\33[32m"
#define PRINT_COLOR_YELLOW    "\33[33m"
#define PRINT_COLOR_BLUE      "\33[34m"
#define PRINT_COLOR_MAGENTA   "\33[35m"
#define PRINT_COLOR_CYAN      "\33[36m"
#define PRINT_COLOR_WHITE     "\33[37m"
//选择输出的颜色，没有过的同学可借鉴一下，卖弄了！
//KERN_DEBUG终端显示没有的话用kmesg
#define Printk(COLOR, ARGs...) \
    printk(COLOR);             \
    printk(KERN_DEBUG ARGs);   \
    printk(PRINT_COLOR_RESET)  \

#ifdef DEBUG_EN
#define MY_DEBUG(ARGs...) Printk(PRINT_COLOR_YELLOW, ARGs)
#else
#define MY_DEBUG(ARGs...) ;
#endif

#define CHILD_NUM 3
#define MY_BIN_SIZE 1
#define to_my_kobj(data) container_of(data, struct my_kobj, kobj)
#define to_my_kobj_child(data)  container_of(data, struct my_kobj_child, kobj_true)
#define to_my_kobj_child2(data)  container_of(data, struct my_kobj_child, kobj_cacogenic)

//长度简单定为PAGE_SIZE吧
struct child_info
{
    char name[PAGE_SIZE];
    int age;
    int height;
    int weight;
};//太像c++类的概念了，受不了！
    
//bin和link，在sysfs一章中我没细讲，大家可以看别人写的，我就偷一下懒了
struct my_kobj_child
{
    struct kobject kobj_cacogenic;//一个畸形的儿子,是bin文件
    struct kobject kobj_virtual;//一个虚拟的儿子,是一个link
    struct kobject kobj_true;//一个真实的儿子
    struct child_info true_child_info;
    char cacogenic_info;//畸形等级
};//三个儿子，两个非人类

struct my_kobj
{
    struct kobject kobj;    
    struct my_kobj_child kobj_child;
};

/***************************************/
//parent
void my_kobj_release(struct kobject *kobj)
{
    struct my_kobj *my_kobj_p = to_my_kobj(kobj);

    MY_DEBUG("my_kobj_release\n");

    kfree(my_kobj_p);
}

static struct kobj_type my_ktype=
{
        .release = my_kobj_release,
        .sysfs_ops = NULL,
        .default_attrs = NULL,
};

/***************************************/

/***************child*******************/

//true child define
static ssize_t my_true_child_show(struct kobject *kobj,struct attribute *attr,char *buf)
{
    struct my_kobj_child *my_kobj_child_p = to_my_kobj_child(kobj);
 
    if (0 == strcmp(attr->name, "name"))
    {
        return snprintf(buf, PAGE_SIZE, "%s\n", my_kobj_child_p->true_child_info.name);
    }
    else if (0 == strcmp(attr->name, "age"))
    {
        return snprintf(buf, PAGE_SIZE, "%d\n", my_kobj_child_p->true_child_info.age);
    }
    else if (0 == strcmp(attr->name, "height"))
    {
        return snprintf(buf, PAGE_SIZE, "%d\n", my_kobj_child_p->true_child_info.height);
    }
    else if (0 == strcmp(attr->name, "weight"))
    {
        return snprintf(buf, PAGE_SIZE, "%d\n", my_kobj_child_p->true_child_info.weight);
    }

    return 0;
}

static ssize_t my_true_child_store(struct kobject *kobj,struct attribute *attr,const char *buf,size_t count)
{
    struct my_kobj_child *my_kobj_child_p = to_my_kobj_child(kobj);

    //没做什么输入的判断，大家不要搞我，输入一些变态字符串
    if (0 == strcmp(attr->name, "name"))
    {
        sscanf(buf, "%s", my_kobj_child_p->true_child_info.name);//输入不要加空格
    }
    else if (0 == strcmp(attr->name, "age"))
    {
        sscanf(buf, "%d", &my_kobj_child_p->true_child_info.age);
    }
    else if (0 == strcmp(attr->name, "height"))
    {
        sscanf(buf, "%d", &my_kobj_child_p->true_child_info.height);
    }
    else if (0 == strcmp(attr->name, "weight"))
    {
        sscanf(buf, "%d", &my_kobj_child_p->true_child_info.weight);
    }

    return count;
}

static struct attribute my_true_child_name =
{
    .name = "name",
    .mode = S_IRUGO | S_IWUSR,//root 用户才能写
};

static struct attribute my_true_child_age =
{
    .name = "age",
    .mode = S_IRUGO | S_IWUSR,//root 用户才能写
};

static struct attribute my_true_child_height =
{
    .name = "height",
    .mode = S_IRUGO | S_IWUSR,//root 用户才能写
};

static struct attribute my_true_child_weight =
{
    .name = "weight",
    .mode = S_IRUGO | S_IWUSR,//root 用户才能写
};

static struct attribute *my_true_child_def[] =
{
    &my_true_child_name,
    &my_true_child_age,
    &my_true_child_height,
    &my_true_child_weight,
    NULL,
};

void my_true_child_release(struct kobject *kobj)
{
    MY_DEBUG("my_true_child_release\n");
}

static struct sysfs_ops my_true_child_op =
{
    .show = my_true_child_show,
    .store = my_true_child_store,
};

static struct kobj_type my_true_child_ktype =
{
    .release = my_true_child_release,
    .sysfs_ops = &my_true_child_op,
    .default_attrs = my_true_child_def,
};
//end true child define

//virtaul child define
static void my_virtaul_child_release(struct kobject *kobj)
{
    MY_DEBUG("my_virtaul_child_release\n");
}

static struct kobj_type my_virtaul_child_ktype =
{
    .release = my_virtaul_child_release,
    .sysfs_ops = NULL,
    .default_attrs = NULL,
};
//end virtaul child define

//cacogenic child define
static void my_cacogenic_child_release(struct kobject *kobj)
{
    MY_DEBUG("my_cacogenic_child_release\n");
}

static ssize_t my_bin_read(struct file *filp, struct kobject *kobj,
                struct bin_attribute *attr,
                char *buf, loff_t off, size_t count)
{
    //我看了at24.c的read，会从eeprom中读256字节信息。

    ssize_t size = 0;
    struct my_kobj_child *my_kobj_child_p = to_my_kobj_child2(kobj);

    while(count)
    {
        *buf = my_kobj_child_p->cacogenic_info;
        buf += 1;
        off += 1;
        count -= 1;
        size += 1;
    }

    return size;
}

static struct bin_attribute my_bin_attr = {
        .attr = {
                .name = "my_bin",
                .mode = S_IRUGO | S_IWUSR,//root 用户才能写
        },
        .size = MY_BIN_SIZE,
        .read = my_bin_read,
        //write和mmap就不实现了
};

static struct kobj_type my_cacogenic_child_ktype =
{
    .release = my_cacogenic_child_release,
    .sysfs_ops = NULL,
    .default_attrs = NULL,
};
//end cacogenic child define

/***************************************/
static struct my_kobj *my_kobj_p;

static int __init my_kobj_init(void)
{
    int ret = 0;
    my_kobj_p = (struct my_kobj *)kzalloc(sizeof(struct my_kobj), GFP_KERNEL);
    if (my_kobj_p == NULL)
    {
        ret = -ENOMEM;
        goto fail;
    }

    snprintf(my_kobj_p->kobj_child.true_child_info.name, PAGE_SIZE, "wwxxxxll");
    my_kobj_p->kobj_child.true_child_info.age = 25;
    my_kobj_p->kobj_child.true_child_info.height = 171;
    my_kobj_p->kobj_child.true_child_info.weight = 77;

    my_kobj_p->kobj_child.cacogenic_info = 1;//初始化畸形等级为1

    ret = kobject_init_and_add(&my_kobj_p->kobj, &my_ktype, NULL, "my_kobj");    
    if (ret)
    {
        goto fail1;
    }
    //kobject_init_and_add会调用kobject_init和kobject_add_varg()
    //kset的关系建立是调用kobj_kset_join(),我就不深入了
    ret = kobject_init_and_add(&my_kobj_p->kobj_child.kobj_cacogenic, &my_cacogenic_child_ktype, &my_kobj_p->kobj, "cacogenic");
    if (ret)
    {
        goto fail2;
    }

    ret = kobject_init_and_add(&my_kobj_p->kobj_child.kobj_true, &my_true_child_ktype, &my_kobj_p->kobj, "true");
    if (ret)
    {
        goto fail3;
    }

    ret = kobject_init_and_add(&my_kobj_p->kobj_child.kobj_virtual, &my_virtaul_child_ktype, &my_kobj_p->kobj, "virtual");
    if (ret)
    {
        goto fail4;
    }
    //不愧为虚拟的，只是连接到true，无实体struct ktype。
    ret = sysfs_create_link(&my_kobj_p->kobj_child.kobj_virtual, &my_kobj_p->kobj_child.kobj_true, "virtual_child");
    if (ret)
    {
        sysfs_remove_link(&my_kobj_p->kobj_child.kobj_virtual, "virtual_child");//我看内核中的程序错误也remove一下，我也这么写了。

        goto fail5;
    }

    ret = sysfs_create_bin_file(&my_kobj_p->kobj_child.kobj_cacogenic, &my_bin_attr);
    if (ret)
    {
        goto fail6;
    }
    return 0;

fail6:
    sysfs_remove_link(&my_kobj_p->kobj_child.kobj_virtual, "virtual_child");
fail5:
    kobject_del(&my_kobj_p->kobj_child.kobj_virtual);
    kobject_put(&my_kobj_p->kobj_child.kobj_virtual);
fail4:
    kobject_del(&my_kobj_p->kobj_child.kobj_true);
    kobject_put(&my_kobj_p->kobj_child.kobj_true);
fail3:
    kobject_del(&my_kobj_p->kobj_child.kobj_cacogenic);
    kobject_put(&my_kobj_p->kobj_child.kobj_cacogenic);
fail2:
    kobject_del(&my_kobj_p->kobj);
    kobject_put(&my_kobj_p->kobj);//会调用my_kobj_release
fail1:
    kfree(my_kobj_p);
fail:
    return ret;
}
static void __exit my_kobj_exit(void)
{
    sysfs_remove_bin_file(&my_kobj_p->kobj_child.kobj_cacogenic, &my_bin_attr);//这个是int返回，有点特别。

    sysfs_remove_link(&my_kobj_p->kobj_child.kobj_virtual, "virtual_child");

    kobject_del(&my_kobj_p->kobj_child.kobj_virtual);
    kobject_put(&my_kobj_p->kobj_child.kobj_virtual);

    kobject_del(&my_kobj_p->kobj_child.kobj_true);
    kobject_put(&my_kobj_p->kobj_child.kobj_true);

    kobject_del(&my_kobj_p->kobj_child.kobj_cacogenic);
    kobject_put(&my_kobj_p->kobj_child.kobj_cacogenic);

    kobject_del(&my_kobj_p->kobj);
    kobject_put(&my_kobj_p->kobj);//会调用my_kobj_release
}

module_init(my_kobj_init);
module_exit(my_kobj_exit);

调试

# insmod kobj.ko

先查看一下，不好意思我的平台没tree命令

# ls /sys/my_kobj/

cacogenic  true      virtual

# ls /sys/my_kobj/true/

age     height name    weight

看名字

# cat/sys/my_kobj/true/name

wwxxxxll

修改名字

# echo wxl >/sys/my_kobj/true/name

# cat/sys/my_kobj/true/name

wxl

看一下年龄

# cat/sys/my_kobj/true/age

25

再看一下virtual

# ls/sys/my_kobj/virtual/

virtual_child

# ls/sys/my_kobj/virtual/virtual_child/

age     height name    weight

他就是true的link

我们通过他来改true的age

# echo 24 >/sys/my_kobj/virtual/virtual_child/age

再看一下true确认

# cat/sys/my_kobj/true/age

24

成功，返老还童！

看一下畸形等级

# hexdump/sys/my_kobj/cacogenic/my_bin

0000000 0001                                  

0000001

1级畸形

完，希望有人喜欢！

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总线，设备和驱动。