接上一篇文章,继续device_add()中的代码:
error = bus_add_device(dev);
if (error)
goto BusError;
在对应总线目录下的
device
目录下创建几个到
device
的链接文件。
error = dpm_sysfs_add(dev);
if (error)
goto DPMError;
device_pm_add(dev);
添加
power
文件。
/* Notify clients of device addition. This call must come
* after dpm_sysf_add() and before kobject_uevent().
*/
if (dev->bus)
blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
BUS_NOTIFY_ADD_DEVICE, dev);
>
调用
bus
的回调函数。
kobject_uevent(&dev->kobj, KOBJ_ADD);
产生一个
add
事件。
bus_probe_device(dev);
这个函数将匹配已经注册到总线的驱动程序,如下:
void bus_probe_device(struct device *dev)
{
struct bus_type *bus = dev->bus;
int ret;
if (bus && bus->p->drivers_autoprobe) {
ret = device_attach(dev);
WARN_ON(ret < 0);
}
}
只有
bus->p->drivers_autoprobe
设置为
1
是才会去匹配,
device_attach()
如下:
int device_attach(struct device *dev)
{
int ret = 0;
down(&dev->sem);
if (dev->driver) {
ret = device_bind_driver(dev);
if (ret == 0)
ret = 1;
else {
dev->driver = NULL;
ret = 0;
}
} else {
pm_runtime_get_noresume(dev);
ret = bus_for_each_drv(dev->bus, NULL, dev, __device_attach);
pm_runtime_put_sync(dev);
}
up(&dev->sem);
return ret;
}
如果已指定了
dev->driver
,则直接在相应的
driver
目录下建立链接文件,将驱动和设备绑定。
int device_bind_driver(struct device *dev)
{
int ret;
ret = driver_sysfs_add(dev);
if (!ret)
driver_bound(dev);
return ret;
}
driver_bound()
函数如下:
static void driver_bound(struct device *dev)
{
if (klist_node_attached(&dev->p->knode_driver)) {
printk(KERN_WARNING "%s: device %s already bound\n",
__func__, kobject_name(&dev->kobj));
; return;
}
pr_debug("driver: '%s': %s: bound to device '%s'\n", dev_name(dev),
__func__, dev->driver->name);
if (dev->bus)
blocking_notifier_call_chain(&dev->bus->p->bus_notifier,
BUS_NOTIFY_BOUND_DRIVER, dev);
klist_add_tail(&dev->p->knode_driver, &dev->driver->p->klist_devices);
}
通知总线绑定驱动,将设备添加到驱动的设备链表。
否则调用
bus_for_each_drv()
匹配总线上的驱动:
int bus_for_each_drv(struct bus_type *bus, struct device_driver *start,
void *data, int (*fn)(struct device_driver *, void *))
{
struct klist_iter i;
struct device_driver *drv;
int error = 0;
if (!bus)
return -EINVAL;
klist_iter_init_node(&bus->p->klist_drivers, &i,
start ? &start->p->knode_bus : NULL);
while ((drv = next_driver(&i)) && !error)
error = fn(drv, data); http://msnpiki./index.php/Main_Page-->
size: 10.5pt"> klist_iter_exit(&i);
return error;
}
历遍总线上的驱动,每次都调用回调函数
fn()
(这里是
__device_attach
),如果
fn()
返回
1
则匹配成功,
__device_attach()
如下:
static int __device_attach(struct device_driver *drv, void *data)
{
struct device *dev = data;
if (!driver_match_device(drv, dev))
return 0;
return driver_probe_device(drv, dev);
}
driver_match_device()
如下:
static inline int driver_match_device(struct device_driver *drv,
struct device *dev)
{
return drv->bus->match ? drv->bus ->match(dev, drv) : 1;
}
用
drv->bus
的
match
方法进行匹配,如果成功就会继续调用
driver_probe_device()
:
int driver_probe_device(struct device_driver *drv, struct device *dev)
{
int ret = 0;
if (!device_is_registered(dev)) http://msnpiki./index.php/Main_Page--> cm 0cm 0pt"> return -ENODEV; pr_debug("bus: '%s': %s: matched device %s with driver %s\n", drv->bus->name, __func__, dev_name(dev), drv->name); pm_runtime_get_noresume(dev); pm_runtime_barrier(dev); ret = really_probe(dev, drv); pm_runtime_put_sync(dev); return ret; } 进行一下验证和同步后调用really_probe()最终详细的匹配: static int really_probe(struct device *dev, struct device_driver *drv) { int ret = 0; atomic_inc(&probe_count); pr_debug("bus: '%s': %s: probing driver %s with device %s\n", drv->bus->name, __func__, drv->name, dev_name(dev)); WARN_ON(!list_empty(&dev->devres_head)); dev->driver = drv; if (driver_sysfs_add(dev)) { printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n", __func__, dev_name(dev)); goto probe_failed; } 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;
}
driver_bound(dev);
ret = 1;
pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
drv->bus->name, __func__, dev_name(dev), drv->name);
goto done;
probe_failed:
devres_release_all(dev);
driver_sysfs_remove(dev);
dev->driver = NULL;
if (ret != -ENODEV && ret != -ENXIO) {
/* driver matched but the probe failed */
printk(KERN_WARNING
"%s: probe of %s failed with error %d\n",
drv->name, dev_name(dev), ret);
}
/*
* Ignore errors returned by ->probe so that the next driver can try * its luck. */ ret = 0; done: atomic_dec(&probe_count); wake_up(&probe_waitqueue); return ret; } 先假定dev的驱动为drv,然后如果总线闪的probe存在,则调用它,否则调用drv的probe()函数,返回0则匹配成功,调用driver_bound()进行设备和驱动的绑定。driver_bound()函数在上面已经分析。 接着device_add()函数中的代码: if (dev->class) { mutex_lock(&dev->class->p->class_mutex); /* tie the class to the device */ klist_add_tail(&dev->knode_class, &dev->class->p->class_devices); /* notify any interfaces that the device is here */ list_for_each_entry(class_intf, &dev->class->p->class_interfaces, node) http://msnpiki./index.php/Main_Page--> b-count: 3"> if (class_intf->add_dev) class_intf->add_dev(dev, class_intf); mutex_unlock(&dev->class->p->class_mutex); } Dev所属class的一些操作。 done: put_device(dev); return error; DPMError: bus_remove_device(dev); BusError: device_remove_attrs(dev); AttrsError: device_remove_class_symlinks(dev); SymlinkError: if (MAJOR(dev->devt)) device_remove_sys_dev_entry(dev); devtattrError: if (MAJOR(dev->devt)) device_remove_file(dev, &devt_attr); ueventattrError: device_remove_file(dev, &uevent_attr); attrError: kobject_uevent(&dev->kobj, KOBJ_REMOVE); kobject_del(&dev->kobj); Error: cleanup_device_parent(dev); if (parent) put_device(parent);
name_error:
kfree(dev->p);
dev->p = NULL;
goto done;
最后是一下除错撤销处理。
}
至此,已经详细的分析了创建和注册设备的函数。
内核撤销设备注册的函数为
device_unregister()
,这里不再分析。
内核提供注册驱动的函数为
driver_register()
:
int driver_register(struct device_driver *drv)
{
int ret;
struct device_driver *other;
BUG_ON(!drv->bus->p);
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);
验证
driver
的包含了需要的方法,并打印信息。
other = driver_find(drv->name, drv->bus);
if (other) { &nb sp; put_driver(other); printk(KERN_ERR "Error: Driver '%s' is already registered, " "aborting...\n", drv->name); return -EBUSY; } 如果驱动已注册则返回-EBUSY。 ret = bus_add_driver(drv); if (ret) return ret; ret = driver_add_groups(drv, drv->groups); if (ret) bus_remove_driver(drv); return ret; } bus_add_driver()代码如下: 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; pr_debug("bus: '%s': add driver %s\n", bus->name, drv->name); priv = kzalloc(sizeof(*priv), GFP_KERNEL); if (!priv) { &
o-hansi-font-family: 'Times New Roman'">同样内核提供
driver_unregister()
函数撤销驱动注册,这里不再分析。
至此,已经清楚了设备驱动模型的 device 、 driver 和 bus ,在此基础上就可以轻松的去分析各个模块的驱动程序了 ^_^!
nbsp; error = -ENOMEM;
goto out_put_bus;
}
klist_init(&priv->klist_devices, NULL, NULL);
priv->driver = drv;
drv->p = priv;
priv->kobj.kset = bus->p->drivers_kset;
error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,
"%s", drv->name);
if (error)
goto out_unregister;
if (drv->bus->p->drivers_autoprobe) {
error = driver_attach(drv);
if (error)
goto out_unregister;
}
klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);
module_add_driver(drv->owner, drv);
error = driver_create_file(drv, &driver_attr_uevent);
if (error) {
printk(KERN_ERR "%s: uevent attr (%s) failed\n",
__func__, drv->name);
}
error = driver_add_attrs(bus, drv);
if (error) {
/* How the hell do we get out of this pickle? Give up */ http://msnpiki./index.php/Main_Page--> t"> printk(KERN_ERR "%s: driver_add_attrs(%s) failed\n", __func__, drv->name); } if (!drv->suppress_bind_attrs) { error = add_bind_files(drv); if (error) { /* Ditto */ printk(KERN_ERR "%s: add_bind_files(%s) failed\n", __func__, drv->name); } } kobject_uevent(&priv->kobj, KOBJ_ADD); return 0; out_unregister: kfree(drv->p); drv->p = NULL; kobject_put(&priv->kobj); out_put_bus: bus_put(bus); return error; } 简单的分析一下:为drv分配内存并初始化,创建文件系统中相应的目录、属性文件和链接,调用driver_attach()匹配总线上的设备,将驱动注册到bus上,产生一个kobject_uevent() ADD事件。详细的过程请参考内核源码。 http://msnpiki./index.php/Main_Page--> |
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来自: langhuayipian > 《linux内核》