linux总线对象bus_type

linux总线对象bus_type

struct bus_type {    const char      *name; //总线名字    struct bus_attribute    *bus_attrs;    struct device_attribute *dev_attrs;    struct driver_attribute *drv_attrs;    int (*match)(struct device *dev, struct device_driver *drv);    int (*uevent)(struct device *dev, struct kobj_uevent_env *env);    int (*probe)(struct device *dev);    int (*remove)(struct device *dev);    void (*shutdown)(struct device *dev);    int (*suspend)(struct device *dev, pm_message_t state);    int (*resume)(struct device *dev);    const struct dev_pm_ops *pm;    struct bus_type_private *p; //管理总线上的设备与驱动};struct bus_type_private {    struct kset subsys; //总线的kset    struct kset *drivers_kset; //驱动对象的kset    struct kset *devices_kset; //设备对象的kset    struct klist klist_devices;    struct klist klist_drivers;    struct blocking_notifier_head bus_notifier;    unsigned int drivers_autoprobe:1;    struct bus_type *bus;};//注册总线/base/bus.cint __init buses_init(void){    bus_kset = kset_create_and_add("bus", &bus_uevent_ops, NULL);    if (!bus_kset)        return -ENOMEM;    return 0;}int bus_register(struct bus_type *bus){    priv = kzalloc(sizeof(struct bus_type_private), GFP_KERNEL);    priv->subsys.kobj.kset = bus_kset;     priv->subsys.kobj.ktype = &bus_ktype; //kobject_type    retval = kobject_set_name(&priv->subsys.kobj, "%s", bus->name);    retval = kset_register(&priv->subsys); //注册subsys的kset    retval = bus_create_file(bus, &bus_attr_uevent); //创建 sysbus 的 attr     priv->devices_kset = kset_create_and_add("devices", NULL,  //创建subsys的kset的driver            &priv-subsys.kobj    priv->drivers_kset = kset_create_and_add("drivers", NULL,  //创建subsys的kset的device            &priv->subsys.kobj);}举例：操作总线属性//操作属性文件static BUS_ATTR(uevent, S_IWUSR, NULL, bus_uevent_store);#define BUS_ATTR(_name, _mode, _show, _store)   \    struct bus_attribute bus_attr_##_name = __ATTR(_name, _mode, _show, _store)举例:int bus_register(struct bus_type *bus){    retval = bus_create_file(bus, &bus_attr_uevent);    retval = add_probe_files(bus);        retval = bus_create_file(bus, &bus_attr_drivers_probe);        retval = bus_create_file(bus, &bus_attr_drivers_autoprobe);}static BUS_ATTR(drivers_autoprobe, S_IWUSR | S_IRUGO,        show_drivers_autoprobe, store_drivers_autoprobe);#define BUS_ATTR(_name, _mode, _show, _store)   \struct bus_attribute bus_attr_##_name = __ATTR(_name, _mode, _show, _store)static ssize_t show_drivers_autoprobe(struct bus_type *bus, char *buf){    return sprintf(buf, "%d\n", bus->p->drivers_autoprobe);}static ssize_t store_drivers_autoprobe(struct bus_type *bus,                       const char *buf, size_t count){    if (buf[0] == '0')        bus->p->drivers_autoprobe = 0;    else        bus->p->drivers_autoprobe = 1;    return count;}//应用空间修改attr文件的值 [root@EmbedSky i2c]# cat drivers_autoprobe 1[root@EmbedSky i2c]# echo 0 > drivers_autoprobe[root@EmbedSky i2c]# cat drivers_autoprobe 0