設(shè)備驅(qū)動模型

1、簡介作者：hjlin內(nèi)核版本：2.6.29設(shè)備驅(qū)動模型框架是linux驅(qū)動編程的基礎(chǔ)。它通過kobject,kset,ktype等底層數(shù)據(jù)結(jié)構(gòu)將 bus_type, device, device_driver等高層數(shù)據(jù)結(jié)構(gòu)組織起來，形成一個層次、分類清晰的驅(qū)動 模型。優(yōu)點如下：代碼重用。將對象抽象為總線、驅(qū)動、設(shè)備三種，各司其職。同一總線的多個驅(qū)動使用 相同的總線對象。同一驅(qū)動可以關(guān)聯(lián)驅(qū)動多個設(shè)備。通過sysfs文件系統(tǒng)，清晰了展示內(nèi)核驅(qū)動模型中的層次關(guān)系。同時sysfs文件系統(tǒng)還提 供了方便的同用戶控件交互的接口?？蚣躶truct kset.t_opsitruct attributestru

2、ct sysfs_ops-const char *name-struct module *owner-mode_t modeTtv+int (*filter) (struct kset *kset, struct kobject *kobj)()+const char *(*name) (struct kset *kset, struct kobject *kobj)()+int (*uevent) (struct kset *kset, struct ko&ct *kobj, struct kobj_uevent_env *env)()+ssize_t (*show) (struct kob

3、ject *, struct attribute *, char *)()+ssize_t (*store) (struct kobject *, stfpct attribute *, const char *, size_t)()uct kobjectstruct kset-struct list_head list-spinlock_t list_lock-struct kobject kobj-struct kset_uevent_ops *uevent_ops-const char *name-struct list_head entry-struct kobject *parent

4、-struct kset *kset-struct kobj_type *ktype-struct sysfs_dirent *sd-struct kref kref-uint state_initialized:1-uint state_in_sysfs:1-uint state_add_uevent_sent:1-unit state_remove_uevent_sent:1-uint uevent_suppress:1struct kobj_*ype-struct sysfs_ops *sysfs_ops-struct attribute *default_attrs+void (*re

5、lease) (struct kobject *kobj)()struct bus_typestruct devicestruct device_driver-const char *name-struct bus_attribute *bus_attrs-struct device_attribute *dev_attrs-struct driver_attribute *drv_attrs-const struct dev_pm_ops *pm-struct bus_type_private *p+int (*match) (struct device *dev, struct devic

6、e_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)()-struct de

7、vice *parent-struct device_private *p-struct kobject kobj-char bus_idBUS_ID_SIZE-const char *init_name-struct device_type *type-struct semaphore sem-struct bus_type *bus-struct device_driver *driver-void *platform_data-struct dev_pm_info power-dev_t devt-spinlock_t devres_lock-struct list_head devre

8、s_head-struct klist_node knode_class-struct class *class-const struct attribute_group *groups+void (*release) (struct device *dev)()-const char *name-struct bus_type *bus-struct module *owner-const char *mod_name-bool suppress_bind_attrs-const struct attribute_group *groups-const struct dev_pm_ops *

9、pm-struct driver_private *p+int (*probe) (struct device *dev)()+int (*remove) (struct device *dev)()+vod (*shutdown) (struct device *dev)()+int (*suspend) (struct device *dev, pm message t state)()+int (*resume) (struct device *dev)()struct bus_type_private-struct kset subsys-struct kset *drivers_ks

10、et-struct kset *devices_kset-struct klist klist_devices-struct klist klist_drivers-struct blocking_notifier_head bus_notifier-unsigned int drivers_autoprobe:1-struct bus_type *busstruct device_privateuct driver_privatestruct klist klist_childrenstruct klist_node knode_parent struct klist_node konde_

11、driver struct klist_node knode_bus void *driver_datastruct device ,device-struct kobject kobj-struct klist klist_devices-struct klist_node knode_bus-struct module_kobject *mkobj-struct device_driver *driverbus_at!ribule-struct attribute attrstruct driver_attribute-struct attribute attr+ssize_t (*sho

12、w) (struct bus_type *bus, char *buf)()+ssize_t (*store) (struct bus_type *bus, const char *buf, size_t count)()+ssize_t (*show) (struct device_driver *driver, char *buf)()+ssize_t (*store) (struct device_driver *driver, const char *buf, size_t count)()struct devic_attribut-struct attribute attr +ssi

13、ze_t (*show) (struct device *dev, char *buf)()+ssize_t (*store) (struct device *dev, const char *buf, size_t count)()數(shù)據(jù)結(jié)構(gòu)KobjectKobject是代表驅(qū)動模型中的一個對象?？偩€、驅(qū)動、設(shè)備都繼承了它。（在結(jié)構(gòu)體中包含 kobject）。每個kobject在sysfs中表現(xiàn)為一個目錄。每個kobject都有一個parent kobject和所屬的kset。Kset就是kobject所屬的kset,通過kset 的鏈表可以找到所有屬于它的kobject。這些kobject進

14、行uevent操作時，都會調(diào)用所屬的kset 的uevent_ops方法。父kobj，用于表示kobject之間或者kobject和kset，kset之間的在sysfs 中的目錄結(jié)構(gòu)關(guān)系。如果父kobj不存在，并且所屬的kset存在的話，則父kobj就是設(shè)置為 所屬的kset的內(nèi)嵌kobj。因此，注冊設(shè)備、驅(qū)動或者總線的時候如果不指定parent kobj的 話，父kobj則會設(shè)置為所屬的kset的kobj。（todo：最好畫圖表示關(guān)系）struct kobject (const char* k_name;struct krefkref;struct list_headentry;連入到所屬的

15、kset的liststruct kobject* parent; /父kobj，如果沒有父kobj，則使用所屬的kset內(nèi)嵌kobjstruct kset* kset; /所屬的kset （如果有的話）struct kobj_type* ktype; /所屬的ktype，如果所屬的kset也有ktype，則用kset的ktype。struct sysfs_dirent ;* sd;Kest通過kset可以將kobject組織成一顆層次樹。struct kset (struct list_headlist; /屬于該kset的kobj鏈表spinlock_tlist_lock;struct ko

16、bjectkobj; 內(nèi)嵌的 kobjectstruct kset_uevent_ops *uevent_ops; /uevent 方法，對所有該 kset 下的 kobj 進彳亍 uevent操作時的方法。；struct kset_uevent_ops (int (*filter)(struct kset *kset, struct kobject *kobj);const char *(*name)(struct kset *kset, struct kobject *kobj);int (*uevent)(struct kset *kset, struct kobject *kobj,

17、struct kobj_uevent_env *env);kobj_typestruct kobj_type (void (*release)(struct kobject *kobj); /kobject 釋放時調(diào)用struct sysfs_ops *sysfs_ops; /臊縱默認屬性的讀寫方法struct attribute *default_attrs; 相應(yīng)的 kobject (kset)的默認屬性。對應(yīng)于 sysfs 下的文 件。;struct sysfs_ops (ssize_t (*show)(struct kobject *, struct attribute *,char

18、*);ssize_t (*store)(struct kobject *,struct attribute *,const char *, size_t);J;struct attribute (const char*name;struct module*owner;mode_t ;mode;bus_type代表一個總線。對應(yīng)/sys/bus下的一個目錄。管理相應(yīng)總線下的所有驅(qū)動和設(shè)備。struct bus_type (const char *name;總線名稱struct bus_attribute *bus_attrs;該總線目錄下的屬性文件以及相應(yīng)的訪問方法struct device_a

19、ttribute *dev_attrs; 該總線設(shè)備子目錄下的屬性文件以及相應(yīng)的訪問方 法struct driver_attribute *drv_attrs; 該總線驅(qū)動子目錄下的屬性文件以及相應(yīng)的訪問方 法int (*match)(struct device *dev, struct device_driver *drv); 驅(qū)動模型進行驅(qū)動和設(shè)備的匹 配時調(diào)用int (*uevent)(struct device *dev, struct kobj_uevent_env *env); /ueven方法int (*probe)(struct device *dev); /match成功之后

20、會調(diào)用。一般該probe方法內(nèi)部會調(diào)用 相應(yīng)的device_driver的probe方法int (*remove)(struct device *dev);void (*shutdown)(struct device *dev);int (*suspend)(struct device *dev, pm_message_t state);int (*suspend_late)(struct device *dev, pm_message_t state);int (*resume_early)(struct device *dev);int (*resume)(struct device *d

21、ev);struct dev_pm_ops *pm;struct bus_type_private *p;struct bus_type_private (struct kset subsys; 總線本身目錄struct kset *drivers_kset; 驅(qū)動目錄struct kset *devices_kset; 設(shè)備目錄struct klist klist_devices;struct klist klist_drivers;struct blocking_notifier_head bus_notifier;unsigned int drivers_autoprobe:1;stru

22、ct bus_type *bus;Devicestruct device (struct device *parent; 父設(shè)備struct device_private *p;struct kobject kobj;char bus_idBUS_ID_SIZE;const char*init_name; /* initial name of the device */struct device_type *type;struct semaphore sem;/* semaphore to synchronize calls to* its driver.*/struct bus_type *

23、bus;/* type of bus device is on */struct device_driver *driver; /* which driver has allocated thisdevice */void *platform_data; /* Platform specific data, device core doesnt touch it */struct dev_pm_info power;#ifdef CONFIG_NUMA int numa_node; /* NUMA node this device is close to */ #endifu64 *dma_m

24、ask; /* dma mask (if dmaable device) */ u64 coherent_dma_mask;/* Like dma_mask, but for alloc_coherent mappings as not all hardware supports 64 bit addresses for consistent allocations such descriptors. */struct device_dma_parameters *dma_parms;struct list_head dma_pools; /* dma pools (if dmable) */

25、struct dma_coherent_mem *dma_mem; /* internal for coherent mem override */* arch specific additions */struct dev_archdata archdata;dev_tdevt;/* dev_t, creates the sysfs dev */spinlock_t struct list_headdevres_lock;devres_head;struct klist_nodestruct classknode_class;*class;const struct attribute_gro

26、up *groups; /* optional groups */void (*release)(struct device *dev);struct device_private (struct klist klist_children; /子設(shè)備的鏈表struct klist_node knode_parent; /作為父設(shè)備的字設(shè)備鏈表(klist_children)的一個節(jié)點 struct klist_node knode_driver; /(作為所屬驅(qū)動的設(shè)備鏈表(klist_devices)的一個節(jié)點 struct klist_node knode_bus; /作為所屬總線的設(shè)備鏈

27、表(klist_devices)的一個節(jié)點 void *driver_data;struct device *device;device_driverstruct device_driver (const char*name;struct bus_type*bus;struct module*owner;const char*mod_name; /* used for built-in modules */int (*probe) (struct device *dev);int (*remove) (struct device *dev);void (shutdown) (struct de

28、vice *dev);int (*suspend) (struct device *dev, pm_message_t state);int (*resume) (struct device *dev);struct attribute_group *groups;struct dev_pm_ops *pm;struct driver_private *p;；struct driver_private (struct kobject kobj;struct klist klist_devices; /所驅(qū)動的設(shè)備的鏈表struct klist_node knode_bus; /作為所屬總線的驅(qū)

29、動鏈表(klist_drivers)的一個節(jié)點 struct module_kobject *mkobj;struct device_driver *driver;基礎(chǔ)方法kobject_add_internalstatic int kobject_add_internal(struct kobject *kobj)將kobject添加到設(shè)備驅(qū)動模型中。主要設(shè)置父kobj以及將自己添加到所屬的kset的list中， 并且在sysfs中創(chuàng)建目錄。父kobj存在否kobject_add_internal()Endkobject_get(kobj-parent)獲取父kobj并增加引用計數(shù)creat

30、e_dir(kobj) 在sysfs中創(chuàng)建kobj相應(yīng)目錄設(shè)置父kobj為所屬的kset的 內(nèi)嵌kobj將kobj加入到所屬kset的 kobj鏈表中 Kobj-entry + kset-listkobject_ueventint kobject_uevent(struct kobject *kobj, enum kobject_action action) send an uevent to userspacekobject_uevent( struct kobject *kobj, enum kobject_action actii rEnd通過Netlink_broadcast(ueve

31、nt_sock,.)發(fā)送出去call_usermodehelper 調(diào)用用戶進程。一般是/sbin/hotplug，手機上一般沒有核心方法注冊總線bus_register(struct bus_type *bus)注冊一個總線到驅(qū)動模型中。在sysfs中的結(jié)構(gòu)是:/sys/bus/platform/|- devices|-.|- drivers|- .|- drivers_autoprobe|- drivers_probe-ueventBUS_ATTR(uevent, S_IWUSR, NULL, bus_uevent_store);屬性的寫方法直接調(diào)用kobject_uevent發(fā)送事件分配

32、Bus.p的空間 bus_type_private設(shè)置Bus內(nèi)建的kobject: name 等于 所屬 kset 為 &bus_kset Ktype等于&bus ktypeIPus)Bus_register(Struct bus_1- *bBus 內(nèi)建 kobj 的所屬 kset 是 bus_kset, bus_kset 是一個 kset，相對于/sys/Bus -目錄。由于bus的內(nèi)建kobj沒有父 kobj。所以Bus_kset將做為它的父 kobj，因此內(nèi)建的kobj的，9，目錄為/ sys/bus/xxx_busint bus_register(struct bus

33、_type *bus)int retval;struct bus_type_private *priv;/初始化private數(shù)據(jù)結(jié)構(gòu)priv = kzalloc(sizeof(struct bus_type_private), GFP_KERNEL);if (!priv)return -ENOMEM;priv-bus = bus;bus-p = priv;BLOCKING_INIT_NOTIFIER_HEAD(&priv-bus_notifier);設(shè)置kobject名稱。即/bus/sys/下的目錄名稱retval = kobject_set_name(&priv-subsys.kobj,

34、 %s, bus-name); if (retval)goto out;priv-subsys.kobj.kset = bus_kset;priv-subsys.kobj.ktype = &bus_ktype;priv-drivers_autoprobe = 1;/注冊內(nèi)嵌ksetretval = kset_register(&priv-subsys);if (retval)goto out;retval = bus_create_file(bus, &bus_attr_uevent);if (retval)goto bus_uevent_fail;創(chuàng)建設(shè)備kset并且注冊priv-devic

35、es_kset = kset_create_and_add(devices”, NULL, &priv-subsys.kobj);if (!priv-devices_kset) ( retval = -ENOMEM; goto bus_devices_fail;創(chuàng)建驅(qū)動kset并且注冊priv-drivers_kset = kset_create_and_add(drivers”, NULL, &priv-subsys.kobj);if (!priv-drivers_kset) ( retval = -ENOMEM; goto bus_drivers_fail;klist_init(&priv

36、-klist_devices, klist_devices_get, klist_devices_put);klist_init(&priv-klist_drivers, NULL, NULL);retval = add_probe_files(bus);if (retval)goto bus_probe_files_fail;retval = bus_add_attrs(bus);if (retval)goto bus_attrs_fail;pr_debug(bus: %s: registered, bus-name);return 0;0 0 0out:return retval;注冊設(shè)備

37、主要有兩個工作，初始化設(shè)備，將設(shè)備掛接到設(shè)備驅(qū)動模型中并且處理uevent事件和自動匹配設(shè)備驅(qū)動。在 platform.c 的 platform_bus_init 方法中使用了 device_register(&platform_bus),注冊了 一個設(shè) 備，該設(shè)備的sys目錄為/sys/devices/platform/。但是一般情況下，內(nèi)核對于不同的總線會提 供不同的封裝方法在內(nèi)部調(diào)用device_register來注冊設(shè)備。比如說platform_register_device， 并且在platform_register_device方法中設(shè)置了 device的父kobj為platfor

38、m_bus，導致所有通 過的 platform_register_device 注冊的設(shè)備的目錄都會在/sys/devices/platform/下 0在sys文件系統(tǒng)中的結(jié)構(gòu)是：todoDev設(shè)置了所屬kset，但是dev的父kobj 一般為被設(shè)置為其他的dev。比如說 platform_device_register 中會將 dev 的 父kobj設(shè)置為platform_bus (相對于/ sys/devices/platform_bus 目錄)，因 此dev在sys中的目錄可能就是/sys/ devices/platform_bus/xxx_devicedevice_register(s

39、truct device-*dev)device_initialize() 設(shè)置內(nèi)嵌kobj的所屬kset為 device ksetdev_set_name(dev, %sH,dev-init_name);設(shè)置內(nèi)嵌kobj的name為Device_create_file(dev, &devt_attr);創(chuàng)建dev屬性文件，讀方法 就是輸出相應(yīng)的主次設(shè)備號Kobject_add(&dev-kobj,dev-kobj.parent, NULL);注冊內(nèi)嵌kobjo這時，已經(jīng)在/sys/devices/xxx/下創(chuàng)建好目錄Device_add_class_symlinks

40、 如果有class，創(chuàng)建subsystem 軟連接到/sys/class/相應(yīng)目 錄EndBus_probe_device探測總線上驅(qū)動和該設(shè)備進行匹配int device_register(struct device *dev)device_initialize(dev);return device_add(dev);void device_initialize(struct device *dev)kobj_set_kset_s(dev, devices_subsys);kobject_init(&dev-kobj);klist_init(&dev-klist_children, klis

41、t_children_get, klist_children_put);INIT_LIST_HEAD(&dev-dma_pools);INIT_LIST_HEAD(&dev-node);init_MUTEX(&dev-sem);spin_lock_init(&dev-devres_lock);INIT_LIST_HEAD(&dev-devres_head);device_init_wakeup(dev, 0);set_dev_node(dev, -1);int device_add(struct device *dev)struct device *parent = NULL;struct c

42、lass_interface *class_intf;int error = -EINVAL;dev = get_device(dev);if (!dev | !strlen(dev-bus_id) goto Error;pr_debug(DEV: registering device: ID = %sn, dev-bus_id);parent = get_device(dev-parent);error = setup_parent(dev, parent);if (error)goto Error;/* first, register with generic layer. */kobje

43、ct_set_name(&dev-kobj, %s, dev-bus_id);error = kobject_add(&dev-kobj);if (error)goto Error;/* notify platform of device entry */if (platform_notify) platform_notify(dev);/* notify clients of device entry (new way) */if (dev-bus)blocking_notifier_call_chain(&dev-bus-bus_notifier, BUS_NOTIFY_ADD_DEVIC

44、E, dev);創(chuàng)建uevent屬性文件。可以通過該文件發(fā)送事件 error = device_create_file(dev, &uevent_attr);if (error)goto attrError;創(chuàng)建dev的屬性文件。if (MAJOR(dev-devt) (error = device_create_file(dev, &devt_attr);if (error)goto ueventattrError;error = device_add_class_symlinks(dev);if (error)goto SymlinkError;創(chuàng)建所屬class, kobject_typ

45、e,以及device本身自帶的屬性文件error = device_add_attrs(dev);if (error)goto AttrsError;創(chuàng)建電源管理子目錄powererror = dpm_sysfs_add(dev);if (error)goto PMError;/將該設(shè)備掛接到電源鏈表下device_pm_add(dev);/將該dev添加到buserror = bus_add_device(dev);if (error)goto BusError;kobject_uevent(&dev-kobj, KOBJ_ADD); 發(fā)送一個 uevent 事件到用戶空間，實現(xiàn)熱插 拔bu

46、s_attach_device(dev); /自動匹配設(shè)備和驅(qū)動if (parent)klist_add_tail(&dev-knode_parent, &parent-klist_children);if (dev-class) (down(&dev-class-sem);/* tie the class to the device */list_add_tail(&dev-node, &dev-class-devices);/* notify any interfaces that the device is here */list_for_each_entry(class_intf, &

47、dev-class-interfaces, node)if (class_intf-add_dev)class_intf-add_dev(dev, class_intf);up(&dev-class-sem);Done:put_device(dev);return error;BusError:device_pm_remove(dev);dpm_sysfs_remove(dev);PMError:if (dev-bus)blocking_notifier_call_chain(&dev-bus-bus_notifier, BUS_NOTIFY_DEL_DEVICE, dev);device_r

48、emove_attrs(dev);AttrsError:device_remove_class_symlinks(dev);SymlinkError:if (MAJOR(dev-devt)device_remove_file(dev, &devt_attr);if (dev-class) (sysfs_remove_link(&dev-kobj, subsystem);/* If this is not a fake compatible device, remove the* symlink from the class to the device. */if (dev-kobj.paren

49、t != &dev-class-subsys.kobj) sysfs_remove_link(&dev-class-subsys.kobj, dev-bus_id);if (parent) (#ifdef CONFIG_SYSFS_DEPRECATEDchar *class_name = make_class_name(dev-class-name, &dev-kobj);if (class_name)sysfs_remove_link(&dev-parent-kobj, class_name);kfree(class_name);#endifsysfs_remove_link(&dev-ko

50、bj, device);ueventattrError:device_remove_file(dev, &uevent_attr);attrError:kobject_uevent(&dev-kobj, KOBJ_REMOVE);kobject_del(&dev-kobj);Error:if (parent)put_device(parent);goto Done;void bus_attach_device(struct device * dev)struct bus_type *bus = dev-bus;int ret = 0;if (bus) (dev-is_registered =

51、1;如果總線自動探測設(shè)備，則進行設(shè)備驅(qū)動匹配。(可以通過bus下的autoprobe屬 性文件查看和修改是否支持自動探測)if (bus-drivers_autoprobe)ret = device_attach(dev);WARN_ON(ret = 0)klist_add_tail(&dev-knode_bus, &bus-klist_devices);elsedev-is_registered = 0;int device_attach(struct device * dev)int ret = 0;down(&dev-sem);if (dev-driver) ret = device_b

52、ind_driver(dev);if (ret = 0)ret = 1;else dev-driver = NULL;ret = 0; else /將設(shè)備和該總線上的所有驅(qū)動進行匹配ret = bus_for_each_drv(dev-bus, NULL, dev, _device_attach);up(&dev-sem);return ret;static int _device_attach(struct device_driver * drv, void * data)struct device * dev = data;return driver_probe_device(drv, d

53、ev);int driver_probe_device(struct device_driver * drv, struct device * dev)int ret = 0;if (!device_is_registered(dev)return -ENODEV;首先調(diào)用總線的match方法進行匹配if (drv-bus-match & !drv-bus-match(dev, drv) goto done;pr_debug(%s: Matched Device %s with Driver %sn, drv-bus-name, dev-bus_id, drv-name);調(diào)用總線或者驅(qū)動的p

54、robe方法繼續(xù)進一步的匹配。ret = really_probe(dev, drv);done:return ret;注冊驅(qū)動int driver_register(struct device_driver *drv)注冊驅(qū)動到設(shè)備驅(qū)動模型，在sysfs創(chuàng)建相應(yīng)的目錄結(jié)構(gòu)，以及自動匹配設(shè)備驅(qū)動。一般在 內(nèi)核中會包裝在其他的方法中在內(nèi)部調(diào)用driver_register方法。在sysfs中的結(jié)構(gòu)是： /sys/bus/platform/drivers/serial8250/|- bind|- serial8250 - ././././devices/platform/serial8250|-

55、uevent-unbind/sys/devices/platform/serial8250I- driver - ./././bus/platform/drivers/serial8250driver_register(struct device driver *drv) ./Drv 設(shè)置了所屬 kset，但是 parent kobj 為空。所以parent kobj也會被設(shè)置為 所屬kset。創(chuàng)建sys目錄時，會在/sys/ bus/xxx_bus/drivers/ 下面。 Kobject_init_and_add注冊內(nèi)建的kobj設(shè)置drv內(nèi)建的kobj的所屬kset為相應(yīng)bus的驅(qū)動kset。Bus-p-drivers kset將drv加入到所屬bus的驅(qū)動鏈表中所屬的bus是否自動套probeBus_