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.c
int __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