Linux设备驱动模型探究--4(driver)

四. 关于驱动(driver)--driver.c

/*数据结构*/
struct device_driver {
const char  *name;  /*驱动名字*/
struct bus_type  *bus; /*驱动所属总线*/
struct module  *owner; /*驱动所在内核模块*/

int (*probe) (struct device *dev);  /*当总线bus将该驱动和对应得设备相互绑定的时候，
           /*内核会首先调用bus的probe函数，如果没有就会调用该probe函数，在driver_register中调用*/

int (*remove) (struct device *dev);  /*原理和probe一样, 但是在driver_unregister中调用*/

struct driver_private *p;
};

驱动上主要的操作：

/*在bus的drivers_kset集合查找驱动，name-查找名称，bus-哪个总线*/-->在bus上查找名称为name的驱动，成功返回driver
struct device_driver *driver_find(const char *name, struct bus_type *bus)
{
struct kobject *k = kset_find_obj(bus->p->drivers_kset, name);
struct driver_private *priv;

if (k) {
priv = to_driver(k);
return priv->driver;
}
return NULL;
}

/**
* driver_register - register driver with bus
* @drv: driver to register
*
* We pass off most of the work to the bus_add_driver() call,
* since most of the things we have to do deal with the bus
* structures.
*/
int driver_register(struct device_driver *drv)
{
int ret;
struct device_driver *other;
if ((drv->bus->probe && drv->probe) ||
     (drv->bus->remove && drv->remove) ||
     (drv->bus->shutdown && drv->shutdown))
  printk(KERN_WARNING "Driver '%s' needs updating - please use "
   "bus_type methods\n", drv->name);

other = driver_find(drv->name, drv->bus);  /*先判断驱动是否注册了*/
if (other) {
  put_driver(other);
  printk(KERN_ERR "Error: Driver '%s' is already registered, "
   "aborting...\n", drv->name);
  return -EBUSY;
}

ret = bus_add_driver(drv);   /*往bus上注册(添加)驱动*/
if (ret)
  return ret;
ret = driver_add_groups(drv, drv->groups);
if (ret)
  bus_remove_driver(drv);
return ret;
}

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***********************接下分析bus_add_driver()****************************

/**
* bus_add_driver - Add a driver to the bus.
* @drv: driver.
*/
int bus_add_driver(struct device_driver *drv)
{
struct bus_type *bus;
struct driver_private *priv;
int error = 0;

bus = bus_get(drv->bus);
if (!bus)
return -EINVAL;

/*初始化驱动私有数据 p*/
priv = kzalloc(sizeof(*priv), GFP_KERNEL);
if (!priv) {
  error = -ENOMEM;
  goto out_put_bus;
}

klist_init(&priv->klist_devices, NULL, NULL);
priv->driver = drv;
drv->p = priv;

/*建立priv->kobj和bus->p->drivers_kset(扮演parent)层次关系,*/
priv->kobj.kset = bus->p->drivers_kset;

error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
         "%s", drv->name);

if (drv->bus->p->drivers_autoprobe) {
  error = driver_attach(drv);   //匹配设备
  if (error)
   goto out_unregister;
}

klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);//向bus驱动链表中添加驱动
module_add_driver(drv->owner, drv);  //向模块中添加驱动

error = driver_create_file(drv, &driver_attr_uevent); //创建uevent属性文件

error = driver_add_attrs(bus, drv); //创先驱动属性文件

/* * kobject_uevent - notify userspace by sending an uevent
*
* @action: action that is happening
* @kobj: struct kobject that the action is happening to
*
*/
kobject_uevent(&priv->kobj, KOBJ_ADD);
return 0;
}

/*参考资料：

Linux设备驱动模型探究--4(driver)

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