你了解Embeded linux中的probe.doc
你了解Embeded linux中的probe一、基于linux-3.18.20、mac驱动二、启动时机：所谓的"probe”，是指在Linux内核中，如果存在相同名称的device和device_driver，内核就会执行device_driver中的probe回调函数，而该函数就是所有driver的入口，可以执行诸如硬件设备初始化、字符设备注册、设备文件操作ops注册等动作（"remove”是它的反操作，发生在device或者device_driver任何一方从内核注销时。将struct device类型的变量注册到内核中时自动触发（device_register，device_add，device_create_vargs，device_create）将struct device_driver类型的变量注册到内核中时自动触发（driver_register）手动查找同一bus下的所有device_driver，如果有和指定device同名的driver，执行probe操作（device_attach）手动查找同一bus下的所有device，如果有和指定driver同名的device，执行probe操作（driver_attach）自行调用driver的probe接口，并在该接口中将该driver绑定到某个device结构中-即设置dev->driver（device_bind_driver）三、流程3.1 注册平台驱动ret = platform_driver_register(#define platform_driver_register(drv) platform_driver_register(drv, THIS_MODULE)_platform_driver_register(drv, THIS_MODULE).return driver_register(int driver_attach(struct device_driver *drv).ret = bus_add_driver(drv);.int bus_add_driver(struct device_driver *drv).return bus_for_each_dev(drv->bus, NULL, drv, _driver_attach);.本函数没有给_driver_attach传递参数。int bus_for_each_dev(struct bus_type *bus, struct device *start, void *data, int (*fn)(struct device *, void *).klist_iter_init_node(while (dev = next_device(.分支一：赋值i->i_klist、i->i_cur因为start为NULL，故传递的第三个参数n为NULLvoid klist_iter_init_node(struct klist *k, struct klist_iter *i,struct klist_node *n)i->i_klist = k;i->i_cur = n;if (n)kref_get(其中i->i_klist = k = ">i->i_cur = n = (start ? 分之二：static struct device *next_device(struct klist_iter *i)struct klist_node *n = klist_next(i);struct device *dev = NULL;struct device_private *dev_prv;if (n)dev_prv = to_device_private_bus(n);dev = dev_prv->device;return dev;#define to_device_private_bus(obj) container_of(obj, struct device_private, knode_bus)参数：i为struct klist_iter struct klist *i_klist;struct klist_node *i_cur;被赋值为i->i_klist = k;i->i_cur = n;next_device(">struct klist_node *n = klist_next(i);n为struct klist_node void *n_klist; /* never access directly */struct list_head n_node;struct kref n_ref;struct kref atomic_t refcount;klist_iter_init_node(">struct klist_node *klist_next(struct klist_iter *i).struct klist_node *last = i->i_cur;if (last)/此处不执行elsenext = to_klist_node(i->i_klist->k_list.next);i->i_cur = NULL;while (next != to_klist_node(">if (likely(!knode_dead(next)kref_get(i->i_cur = next;break;next = to_klist_node(next->n_node.next);.staTIc struct klist_node *to_klist_node(struct list_head *n)return container_of(n, struct klist_node, n_node);取出了包含i->i_klist->k_list.next的n_node指针，不过next所指的和n_node地址偏差一个head指针（list_head包括head和next俩指针）。while循环是从第一个目标to_klist_node(i->i_klist->k_list.next)循环，当再次循环到头节点to_klist_node(">还一个结束的条件，当循环到knode_dead(next)为真时break，不过，likely说明了next通常不会是dead的。Klist_iter找到合适的即停止搜索，找到此处的device_private的device。此结构即为传入probe函数的参数。找到参数后，继续执行return bus_for_each_dev(drv->bus, NULL, drv, _driver_attach);中error = fn(dev, data);即_driver_attach函数。第一个参数dev为刚刚while (dev = next_device(">staTIc int _driver_attach(struct device *dev, void *data).if (!dev->driver)driver_probe_device(drv, dev);.int driver_probe_device(struct device_driver *drv, struct device *dev).ret = really_probe(dev, drv);.staTIc int really_probe(struct device *dev, struct device_driver *drv).if (dev->bus->probe)ret = dev->bus->probe(dev);if (ret)goto probe_failed;else if (drv->probe)ret = drv->probe(dev);if (ret)goto probe_failed;.staTIc struct platform_driver usrmac_dev_driver = .probe = usrmac_dev_probe,.remove = usrmac_dev_remove,.suspend = usrmac_dev_suspend,.resume = usrmac_dev_resume,.driver =.owner = THIS_MODULE,.name = USRMAC_DRIVER_NAME,.of_match_table = usrmac_of_match,;static int usrmac_dev_probe(struct platform_device *pdev)/struct platform_device *pdev即Klist_iter找到的
