驱动之路-设备模型之上层模型
一、重要知识点：
设备模型由总线、设备、驱动三要素组成。
底层模型决定上层模型，在总线，设备，驱动的结构体中你总是可以看到它们间接或者直接的包含了kobject结构或kset结构。
1.总线
总线是处理器和设备之间的通道，在设备模型中，所有设备都通过总线相连，甚至内部的虚拟“platform”总线。在linux设备模型中，总线由bus_type结构表示。定义在中。
总线描述
structbus_type{
constchar*name;//总线名称
structbus_attribute*bus_attrs//总线属性
structdevice_attribute*dev_attrs;//设备属性
structdriver_attribute*drv_attrs;//驱动属性
int(*match)(structdevice*dev,structdevice_driver*drv);
int(*uevent)(structdevice*dev,structkobj_uevent_env*env);
int(*probe)(structdevice*dev);
int(*remove)(structdevice*dev);
void(*shutdown)(structdevice*dev);
int(*suspend)(structdevice*dev,pm_message_tstate);
int(*suspend_late)(structdevice*dev,pm_message_tstate);
int(*resume_early)(structdevice*dev);
int(*resume)(structdevice*dev);
structdev_pm_ops*pm;
structbus_type_private*p;
};
struct bus_type {const char *name;//总线名称struct bus_attribute *bus_attrs//总线属性struct device_attribute *dev_attrs;//设备属性struct driver_attribute *drv_attrs;//驱动属性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 (*suspend_late)(struct device *dev, pm_message_t state);int (*resume_early)(struct device *dev);int (*resume)(struct device *dev);struct dev_pm_ops *pm;struct bus_type_private *p;};
bus_type的bus_type_private成员
structbus_type_private{
structksetsubsys;
structkset*drivers_kset;
structkset*devices_kset;
structklistklist_devices;
structklistklist_drivers;
structblocking_notifier_headbus_notifier;
unsignedintdrivers_autoprobe:1;
structbus_type*bus;
};
struct bus_type_private {struct kset subsys;struct kset *drivers_kset;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 *bus;};
可以看出该结构体中包含了有device和dirver的kset对象。
总线的注册：
int bus_register(structbus_type *bus);
如果成功，新的总线将被添加到系统，在/sys/bus目录下可以看到。
我们在深入看这个函数
intbus_register(structbus_type*bus)
{
intretval;
structbus_type_private*priv;
priv=kzalloc(sizeof(structbus_type_private),gfp_kernel);
if(!priv)
return-enomem;
priv->busbus=bus;
bus->p=priv;
int bus_register(struct bus_type *bus){int retval;struct bus_type_private *priv;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);
retval=kobject_set_name(&priv->subsys.kobj,%s,bus->name);
if(retval)
gotoout;
priv->subsys.kobj.kset=bus_kset;
priv->subsys.kobj.ktype=&bus_ktype;
priv->drivers_autoprobe=1;
retval=kset_register(&priv->subsys);
if(retval)
gotoout;
retval=bus_create_file(bus,&bus_attr_uevent);
if(retval)
gotobus_uevent_fail;
priv->devices_kset=kset_create_and_add(devices,null,
&priv->subsys.kobj);
if(!priv->devices_kset){
retval=-enomem;
gotobus_devices_fail;
}
priv->drivers_kset=kset_create_and_add(drivers,null,
&priv->subsys.kobj);
if(!priv->drivers_kset){
retval=-enomem;
gotobus_drivers_fail;
}
klist_init(&priv->klist_devices,klist_devices_get,klist_devices_put);
klist_init(&priv->klist_drivers,null,null);
retval=add_probe_files(bus);
if(retval)
gotobus_probe_files_fail;
retval=bus_add_attrs(bus);
if(retval)
gotobus_attrs_fail;
pr_debug(bus:'%s':registered\n,bus->name);
return0;
bus_attrs_fail:
remove_probe_files(bus);
bus_probe_files_fail:
kset_unregister(bus->p->drivers_kset);
bus_drivers_fail:
kset_unregister(bus->p->devices_kset);
bus_devices_fail:
bus_remove_file(bus,&bus_attr_uevent);
bus_uevent_fail:
kset_unregister(&bus->p->subsys);
kfree(bus->p);
out:
returnretval;
}
blocking_init_notifier_head(&priv->bus_notifier);retval = kobject_set_name(&priv->subsys.kobj, %s, bus->name);if (retval)goto out;priv->subsys.kobj.kset = bus_kset;priv->subsys.kobj.ktype = &bus_ktype;priv->drivers_autoprobe = 1;retval = kset_register(&priv->subsys);if (retval)goto out;retval = bus_create_file(bus, &bus_attr_uevent);if (retval)goto bus_uevent_fail;priv->devices_kset = kset_create_and_add(devices, null,&priv->subsys.kobj);if (!priv->devices_kset) {retval = -enomem;goto bus_devices_fail;}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->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\n, bus->name);return 0;bus_attrs_fail:remove_probe_files(bus);bus_probe_files_fail:kset_unregister(bus->p->drivers_kset);bus_drivers_fail:kset_unregister(bus->p->devices_kset);bus_devices_fail:bus_remove_file(bus, &bus_attr_uevent);bus_uevent_fail:kset_unregister(&bus->p->subsys);kfree(bus->p);out:return retval;}
从这里
priv->subsys.kobj.kset = bus_kset;
priv->subsys.kobj.ktype = &bus_ktype;
可以看得出总线初始化了自己的kset对象。
总线的删除
void bus_unregister(struct bus_type *bus);
总线的match方法
int (*match)(struct device *dev, struct device_driver *drv);
当一个新设备或者驱动被添加到这个总线时，该方法被调用，用于判断指定的驱动程序是否能处理指定的设备。若可以，则返回非0值。下面的测试程序采用匹配设备的dev->bus_id字符串和驱动的drv->name字符串是否相同来判断驱动是否能处理该设备。
总线uevent方法
int (*uevent)(structdevice *dev, char **envp, int num_envp)
在为用户产生热插拔事件之前，这个方法允许总线添加环境变量。
总线属性由结构bus_attribute描述：
struct bus_attribute {
struct attribute attr;
ssize_t (*show)(struct bus_type *bus,char *buf);
ssize_t (*store)(struct bus_type *bus,const char *buf, size_t count);
};
bus_attr(name,mode, show, store)
在编译时创建和初始化bus_attribute结构，它将bus_attr_作为给定前缀来创建总线的真正名称。
如：static bus_attr(version, s_irugo, show_bus_version, null);
将创建一个bus_attr_version结构体对象。
int bus_create_file(struct bus_type *bus, struct bus_attribute *attr)
创建属性文件
void bus_remove_file(struct bus_type *bus, struct bus_attribute *attr)
删除属性文件
2.设备
structdevice{
structklistklist_children;
structklist_nodeknode_parent;/*nodeinsiblinglist*/
structklist_nodeknode_driver;
structklist_nodeknode_bus;
structdevice*parent;
structkobjectkobj;
charbus_id[bus_id_size];/*positiononparentbus*/
unsigneduevent_suppress:1;
constchar*init_name;/*initialnameofthedevice*/
structdevice_type*type;
structsemaphoresem;/*semaphoretosynchronizecallsto
*itsdriver.
*/
structbus_type*bus;/*typeofbusdeviceison*/
structdevice_driver*driver;/*whichdriverhasallocatedthis
device*/
void*driver_data;/*dataprivatetothedriver*/
void*platform_data;/*platformspecificdata,device
coredoesn'ttouchit*/
structdev_pm_infopower;
#ifdefconfig_numa
intnuma_node;/*numanodethisdeviceiscloseto*/
#endif
u64*dma_mask;/*dmamask(ifdma'abledevice)*/
u64coherent_dma_mask;/*likedma_mask,butfor
alloc_coherentmappingsas
notallhardwaresupports
64bitaddressesforconsistent
allocationssuchdescriptors.*/
structdevice_dma_parameters*dma_parms;
structlist_headdma_pools;/*dmapools(ifdma'ble)*/
structdma_coherent_mem*dma_mem;/*internalforcoherentmem
override*/
/*archspecificadditions*/
structdev_archdataarchdata;
dev_tdevt;/*dev_t,createsthesysfsdev*/
spinlock_tdevres_lock;
structlist_headdevres_head;
structklist_nodeknode_class;
structclass*class;
structattribute_group**groups;/*optionalgroups*/
void(*release)(structdevice*dev);
};
struct device {struct klist klist_children;struct klist_nodeknode_parent;/* node in sibling list */struct klist_nodeknode_driver;struct klist_nodeknode_bus;struct device *parent;struct kobject kobj;char bus_id[bus_id_size];/* position on parent bus */unsigned uevent_suppress:1;const char *init_name; /* initial name of the device */struct device_type*type;struct semaphoresem;/* semaphore to synchronize calls to* its driver.*/struct bus_type*bus;/* type of bus device is on */struct device_driver *driver;/* which driver has allocated thisdevice */void *driver_data;/* data private to the driver */void *platform_data;/* platform specific data, devicecore doesn't touch it */struct dev_pm_infopower;#ifdef config_numaint numa_node;/* numa node this device is close to */#endifu64 *dma_mask;/* dma mask (if dma'able device) */u64 coherent_dma_mask;/* like dma_mask, but foralloc_coherent mappings asnot all hardware supports64 bit addresses for consistentallocations such descriptors. */struct device_dma_parameters *dma_parms;struct list_headdma_pools;/* dma pools (if dma'ble) */struct dma_coherent_mem*dma_mem; /* internal for coherent memoverride *//* arch specific additions */struct dev_archdataarchdata;dev_t devt;/* dev_t, creates the sysfs dev */spinlock_t devres_lock;struct list_headdevres_head;struct klist_nodeknode_class;struct class *class;struct attribute_group**groups;/* optional groups */void (*release)(struct device *dev);};
可以看出device结构体中也包含了一个kobject对象
intdevice_register(struct device *dev);
注册设备
vioddevice_unregister(struct device *dev)
注销设备
设备属性由struct device_attribute描述
structdevice_attribute {
struct attribute attr;
ssize_t (*show)(struct device *dev,struct device_attribute *attr,
char *buf);
ssize_t (*store)(struct device *dev,struct device_attribute *attr,
const char *buf, size_t count);
};
int device_create_file(struct device *dev, struct device_attibute *entry)
创建属性文件
void device_remove_file(struct device *dev, struct device_attibute *entry)
删除属性文件
3.驱动
驱动程序由struct device_driver描述：
structdevice_driver{
constchar*name;
structbus_type*bus;
structmodule*owner;
constchar*mod_name;/*usedforbuilt-inmodules*/
int(*probe)(structdevice*dev);
int(*remove)(structdevice*dev);
void(*shutdown)(structdevice*dev);
int(*suspend)(structdevice*dev,pm_message_tstate);
int(*resume)(structdevice*dev);
structattribute_group**groups;
structdev_pm_ops*pm;
structdriver_private*p;
};
struct 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 device *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;};
在看device_dirver的driver_private 对象
struct driver_private {
struct kobject kobj;
struct klist klist_devices;
struct klist_node knode_bus;
struct module_kobject *mkobj;
struct device_driver *driver;
};
可以看出driver_private结构体中也包含了一个kobject对象。和连接设备的链表。
当总线的match返回非0值，也就是总线找到与驱动相匹配的设备时，驱动的probe的函数将被调用。
当设备从系统总删除是remove被调用。
当系统关机的时候shutdown被调用。
int driver_register(structdevice_driver *drv)
在总线上注册驱动
void driver_unregister(struct device_driver *drv)
载总线上注销驱动
驱动的属性使用structdriver_attribute来描述
structdriver_attribute{
structattribue attr;
ssize_t(*show)(struct device_driver *drv, const char *buf);
ssize_t(*store)(struct device_driver *drv, const char *buf, size_t count);
}
int dirver_create_file(struct device_driver *drv, struct driver_attribute *attr);
创建属性文件
void driver_remove_file struct device_driver *drv, struct driver_attribute *attr);
删除属性文件
二、测试模块
1.bus
#include
#include
#include
#include
#include
module_author(davidxie);
module_license(dualbsd/gpl);
staticchar*version=$revision:1.9{1}quot;;
staticintmy_match(structdevice*dev,structdevice_driver*driver)
{
return!strncmp(dev->bus_id,driver->name,strlen(driver->name));
}
staticvoidmy_bus_release(structdevice*dev)
{
printk(kern_debugmybusrelease\n);
}
structdevicemy_bus={
.bus_id=my_bus0,
.release=my_bus_release
};
structbus_typemy_bus_type={
.name=my_bus,
.match=my_match,
};
export_symbol(my_bus);
export_symbol(my_bus_type);
/*
*exportasimpleattribute.
*/
staticssize_tshow_bus_version(structbus_type*bus,char*buf)
{
returnsnprintf(buf,page_size,%s\n,version);
}
staticbus_attr(version,s_irugo,show_bus_version,null);
staticint__initmy_bus_init(void)
{
intret;
/*注册总线*/
ret=bus_register(&my_bus_type);
if(ret)
returnret;
/*创建属性文件*/
if(bus_create_file(&my_bus_type,&bus_attr_version))
printk(kern_noticefailtocreateversionattribute!\n);
/*注册总线设备*/
ret=device_register(&my_bus);
if(ret)
printk(kern_noticefailtoregisterdevice:my_bus!\n);
returnret;
}
staticvoidmy_bus_exit(void)
{
device_unregister(&my_bus);
bus_unregister(&my_bus_type);
}
module_init(my_bus_init);
module_exit(my_bus_exit);
#include #include #include #include #include module_author(david xie);module_license(dual bsd/gpl);static char *version = $revision: 1.9 {1}quot;;static int my_match(struct device *dev, struct device_driver *driver){return !strncmp(dev->bus_id, driver->name, strlen(driver->name));}static void my_bus_release(struct device *dev){printk(kern_debug my bus release\n);}struct device my_bus = {.bus_id = my_bus0,.release = my_bus_release};struct bus_type my_bus_type = {.name = my_bus,.match = my_match,};export_symbol(my_bus);export_symbol(my_bus_type);/** export a simple attribute.*/static ssize_t show_bus_version(struct bus_type *bus, char *buf){return snprintf(buf, page_size, %s\n, version);}static bus_attr(version, s_irugo, show_bus_version, null);static int __init my_bus_init(void){int ret;/*注册总线*/ret = bus_register(&my_bus_type);if (ret)return ret;/*创建属性文件*/if (bus_create_file(&my_bus_type, &bus_attr_version))printk(kern_notice fail to create version attribute!\n);/*注册总线设备*/ret = device_register(&my_bus);if (ret)printk(kern_notice fail to register device:my_bus!\n);return ret;}static void my_bus_exit(void){device_unregister(&my_bus);bus_unregister(&my_bus_type);}module_init(my_bus_init);module_exit(my_bus_exit);
创建一条名为my_bus_type的总线和一个名为my_bus的总线设备，注意总线也是一个设备，也需要注册。
测试结果：
2.device
#include
#include
#include
#include
#include
module_author(davidxie);
module_license(dualbsd/gpl);
externstructdevicemy_bus;
externstructbus_typemy_bus_type;
/*whyneedthis?*/
staticvoidmy_dev_release(structdevice*dev)
{
}
structdevicemy_dev={
.bus=&my_bus_type,
.parent=&my_bus,
.release=my_dev_release,
};
/*
*exportasimpleattribute.
*/
staticssize_tmydev_show(structdevice*dev,char*buf)
{
returnsprintf(buf,%s\n,thisismydevice!);
}
staticdevice_attr(dev,s_irugo,mydev_show,null);
staticint__initmy_device_init(void)
{
intret=0;
/*初始化设备*/
strncpy(my_dev.bus_id,my_dev,bus_id_size);
/*注册设备*/
device_register(&my_dev);
/*创建属性文件*/
device_create_file(&my_dev,&dev_attr_dev);
returnret;
}
staticvoidmy_device_exit(void)
{
device_unregister(&my_dev);
}
module_init(my_device_init);
module_exit(my_device_exit);
#include #include #include #include #include module_author(david xie);module_license(dual bsd/gpl);extern struct device my_bus;extern struct bus_type my_bus_type;/* why need this ?*/static void my_dev_release(struct device *dev){}struct device my_dev = {.bus = &my_bus_type,.parent = &my_bus,.release = my_dev_release,};/** export a simple attribute.*/static ssize_t mydev_show(struct device *dev, char *buf){return sprintf(buf, %s\n, this is my device!);}static device_attr(dev, s_irugo, mydev_show, null);static int __init my_device_init(void){int ret = 0;/* 初始化设备 */strncpy(my_dev.bus_id, my_dev, bus_id_size);/*注册设备*/device_register(&my_dev);/*创建属性文件*/device_create_file(&my_dev, &dev_attr_dev);return ret;}static void my_device_exit(void){device_unregister(&my_dev);}module_init(my_device_init);module_exit(my_device_exit);
注册一个bus_id即名字为my_dev的设备，该设备的bus成员指向上一步创建的my_bus_type总线，parent成员指向上一步创建的my_bus总线设备。
测试结果：
3.driver
#include
#include
#include
#include
#include
module_author(davidxie);
module_license(dualbsd/gpl);
externstructbus_typemy_bus_type;
staticintmy_probe(structdevice*dev)
{
printk(driverfounddevicewhichmydrivercanhandle!\n);
return0;
}
staticintmy_remove(structdevice*dev)
{
printk(driverfounddeviceunpluged!\n);
return0;
}
structdevice_drivermy_driver={
.name=my_dev,
.bus=&my_bus_type,
.probe=my_probe,
.remove=my_remove,
};
/*
*exportasimpleattribute.
*/
staticssize_tmydriver_show(structdevice_driver*driver,char*buf)
{
returnsprintf(buf,%s\n,thisismydriver!);
}
staticdriver_attr(drv,s_irugo,mydriver_show,null);
staticint__initmy_driver_init(void)
{
intret=0;
/*注册驱动*/
driver_register(&my_driver);
/*创建属性文件*/
driver_create_file(&my_driver,&driver_attr_drv);
returnret;
}
staticvoidmy_driver_exit(void)
{
driver_unregister(&my_driver);
}
module_init(my_driver_init);
module_exit(my_driver_exit);
#include #include #include #include #include module_author(david xie);module_license(dual bsd/gpl);extern struct bus_type my_bus_type;static int my_probe(struct device *dev){printk(driver found device which my driver can handle!\n);return 0;}static int my_remove(struct device *dev){printk(driver found device unpluged!\n);return 0;}struct device_driver my_driver = {.name = my_dev,.bus = &my_bus_type,.probe = my_probe,.remove= my_remove,};/** export a simple attribute.*/static ssize_t mydriver_show(struct device_driver *driver, char *buf){return sprintf(buf, %s\n, this is my driver!);}static driver_attr(drv, s_irugo, mydriver_show, null);static int __init my_driver_init(void){int ret = 0;/*注册驱动*/driver_register(&my_driver);/*创建属性文件*/driver_create_file(&my_driver, &driver_attr_drv);return ret;}static void my_driver_exit(void){driver_unregister(&my_driver);}module_init(my_driver_init);module_exit(my_driver_exit);
创建一个名为“bus_dev”的驱动，并将bus成员指向第一步创建的my_bus_type总线
测试结果：
关于加快区块链产业发展的六条措施正式发布
近几年，我国直线马达出口数量不断减少的原因
嵌入式经典面试题
海信品质之家24日落地长沙，还要推出限量版小龙虾
用纸板制作抓娃娃机
驱动之路-设备模型之上层模型
过去十年，中国制造业升级可谓如火如荼
有源232转485转换器
亚马逊发布了其最新版本的Prime Air递送无人机
什么是分散加载文件？
三星S8/S8 Plus 于4月10日开始接受预订，售价将为人民币5824元
ToughSonic 14超声波传感器的特点优势及应用范围
音圈模组加持的3D打印血管支架已被成功研制出
数字隔离器芯片哪款默认输出低电平
智能座舱主流音频架构设计方案
RTX 3060笔记本正式上市：显卡集成3840个流处理器 支持光线追踪
积分电路的作用是什么
网络安全股悄然大热 监管机构对数据隐私要求趋严
iPhoneXSMax值不值得买
Nuro 机器人送货车将在美国德克萨斯州进行递送服务
设备模型由总线、设备、驱动三要素组成。
底层模型决定上层模型，在总线，设备，驱动的结构体中你总是可以看到它们间接或者直接的包含了kobject结构或kset结构。
1.总线
总线是处理器和设备之间的通道，在设备模型中，所有设备都通过总线相连，甚至内部的虚拟“platform”总线。在linux设备模型中，总线由bus_type结构表示。定义在中。
总线描述
structbus_type{
constchar*name;//总线名称
structbus_attribute*bus_attrs//总线属性
structdevice_attribute*dev_attrs;//设备属性
structdriver_attribute*drv_attrs;//驱动属性
int(*match)(structdevice*dev,structdevice_driver*drv);
int(*uevent)(structdevice*dev,structkobj_uevent_env*env);
int(*probe)(structdevice*dev);
int(*remove)(structdevice*dev);
void(*shutdown)(structdevice*dev);
int(*suspend)(structdevice*dev,pm_message_tstate);
int(*suspend_late)(structdevice*dev,pm_message_tstate);
int(*resume_early)(structdevice*dev);
int(*resume)(structdevice*dev);
structdev_pm_ops*pm;
structbus_type_private*p;
};
struct bus_type {const char *name;//总线名称struct bus_attribute *bus_attrs//总线属性struct device_attribute *dev_attrs;//设备属性struct driver_attribute *drv_attrs;//驱动属性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 (*suspend_late)(struct device *dev, pm_message_t state);int (*resume_early)(struct device *dev);int (*resume)(struct device *dev);struct dev_pm_ops *pm;struct bus_type_private *p;};
bus_type的bus_type_private成员
structbus_type_private{
structksetsubsys;
structkset*drivers_kset;
structkset*devices_kset;
structklistklist_devices;
structklistklist_drivers;
structblocking_notifier_headbus_notifier;
unsignedintdrivers_autoprobe:1;
structbus_type*bus;
};
struct bus_type_private {struct kset subsys;struct kset *drivers_kset;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 *bus;};
可以看出该结构体中包含了有device和dirver的kset对象。
总线的注册：
int bus_register(structbus_type *bus);
如果成功，新的总线将被添加到系统，在/sys/bus目录下可以看到。
我们在深入看这个函数
intbus_register(structbus_type*bus)
{
intretval;
structbus_type_private*priv;
priv=kzalloc(sizeof(structbus_type_private),gfp_kernel);
if(!priv)
return-enomem;
priv->busbus=bus;
bus->p=priv;
int bus_register(struct bus_type *bus){int retval;struct bus_type_private *priv;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);
retval=kobject_set_name(&priv->subsys.kobj,%s,bus->name);
if(retval)
gotoout;
priv->subsys.kobj.kset=bus_kset;
priv->subsys.kobj.ktype=&bus_ktype;
priv->drivers_autoprobe=1;
retval=kset_register(&priv->subsys);
if(retval)
gotoout;
retval=bus_create_file(bus,&bus_attr_uevent);
if(retval)
gotobus_uevent_fail;
priv->devices_kset=kset_create_and_add(devices,null,
&priv->subsys.kobj);
if(!priv->devices_kset){
retval=-enomem;
gotobus_devices_fail;
}
priv->drivers_kset=kset_create_and_add(drivers,null,
&priv->subsys.kobj);
if(!priv->drivers_kset){
retval=-enomem;
gotobus_drivers_fail;
}
klist_init(&priv->klist_devices,klist_devices_get,klist_devices_put);
klist_init(&priv->klist_drivers,null,null);
retval=add_probe_files(bus);
if(retval)
gotobus_probe_files_fail;
retval=bus_add_attrs(bus);
if(retval)
gotobus_attrs_fail;
pr_debug(bus:'%s':registered\n,bus->name);
return0;
bus_attrs_fail:
remove_probe_files(bus);
bus_probe_files_fail:
kset_unregister(bus->p->drivers_kset);
bus_drivers_fail:
kset_unregister(bus->p->devices_kset);
bus_devices_fail:
bus_remove_file(bus,&bus_attr_uevent);
bus_uevent_fail:
kset_unregister(&bus->p->subsys);
kfree(bus->p);
out:
returnretval;
}
blocking_init_notifier_head(&priv->bus_notifier);retval = kobject_set_name(&priv->subsys.kobj, %s, bus->name);if (retval)goto out;priv->subsys.kobj.kset = bus_kset;priv->subsys.kobj.ktype = &bus_ktype;priv->drivers_autoprobe = 1;retval = kset_register(&priv->subsys);if (retval)goto out;retval = bus_create_file(bus, &bus_attr_uevent);if (retval)goto bus_uevent_fail;priv->devices_kset = kset_create_and_add(devices, null,&priv->subsys.kobj);if (!priv->devices_kset) {retval = -enomem;goto bus_devices_fail;}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->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\n, bus->name);return 0;bus_attrs_fail:remove_probe_files(bus);bus_probe_files_fail:kset_unregister(bus->p->drivers_kset);bus_drivers_fail:kset_unregister(bus->p->devices_kset);bus_devices_fail:bus_remove_file(bus, &bus_attr_uevent);bus_uevent_fail:kset_unregister(&bus->p->subsys);kfree(bus->p);out:return retval;}
从这里
priv->subsys.kobj.kset = bus_kset;
priv->subsys.kobj.ktype = &bus_ktype;
可以看得出总线初始化了自己的kset对象。
总线的删除
void bus_unregister(struct bus_type *bus);
总线的match方法
int (*match)(struct device *dev, struct device_driver *drv);
当一个新设备或者驱动被添加到这个总线时，该方法被调用，用于判断指定的驱动程序是否能处理指定的设备。若可以，则返回非0值。下面的测试程序采用匹配设备的dev->bus_id字符串和驱动的drv->name字符串是否相同来判断驱动是否能处理该设备。
总线uevent方法
int (*uevent)(structdevice *dev, char **envp, int num_envp)
在为用户产生热插拔事件之前，这个方法允许总线添加环境变量。
总线属性由结构bus_attribute描述：
struct bus_attribute {
struct attribute attr;
ssize_t (*show)(struct bus_type *bus,char *buf);
ssize_t (*store)(struct bus_type *bus,const char *buf, size_t count);
};
bus_attr(name,mode, show, store)
在编译时创建和初始化bus_attribute结构，它将bus_attr_作为给定前缀来创建总线的真正名称。
如：static bus_attr(version, s_irugo, show_bus_version, null);
将创建一个bus_attr_version结构体对象。
int bus_create_file(struct bus_type *bus, struct bus_attribute *attr)
创建属性文件
void bus_remove_file(struct bus_type *bus, struct bus_attribute *attr)
删除属性文件
2.设备
structdevice{
structklistklist_children;
structklist_nodeknode_parent;/*nodeinsiblinglist*/
structklist_nodeknode_driver;
structklist_nodeknode_bus;
structdevice*parent;
structkobjectkobj;
charbus_id[bus_id_size];/*positiononparentbus*/
unsigneduevent_suppress:1;
constchar*init_name;/*initialnameofthedevice*/
structdevice_type*type;
structsemaphoresem;/*semaphoretosynchronizecallsto
*itsdriver.
*/
structbus_type*bus;/*typeofbusdeviceison*/
structdevice_driver*driver;/*whichdriverhasallocatedthis
device*/
void*driver_data;/*dataprivatetothedriver*/
void*platform_data;/*platformspecificdata,device
coredoesn'ttouchit*/
structdev_pm_infopower;
#ifdefconfig_numa
intnuma_node;/*numanodethisdeviceiscloseto*/
#endif
u64*dma_mask;/*dmamask(ifdma'abledevice)*/
u64coherent_dma_mask;/*likedma_mask,butfor
alloc_coherentmappingsas
notallhardwaresupports
64bitaddressesforconsistent
allocationssuchdescriptors.*/
structdevice_dma_parameters*dma_parms;
structlist_headdma_pools;/*dmapools(ifdma'ble)*/
structdma_coherent_mem*dma_mem;/*internalforcoherentmem
override*/
/*archspecificadditions*/
structdev_archdataarchdata;
dev_tdevt;/*dev_t,createsthesysfsdev*/
spinlock_tdevres_lock;
structlist_headdevres_head;
structklist_nodeknode_class;
structclass*class;
structattribute_group**groups;/*optionalgroups*/
void(*release)(structdevice*dev);
};
struct device {struct klist klist_children;struct klist_nodeknode_parent;/* node in sibling list */struct klist_nodeknode_driver;struct klist_nodeknode_bus;struct device *parent;struct kobject kobj;char bus_id[bus_id_size];/* position on parent bus */unsigned uevent_suppress:1;const char *init_name; /* initial name of the device */struct device_type*type;struct semaphoresem;/* semaphore to synchronize calls to* its driver.*/struct bus_type*bus;/* type of bus device is on */struct device_driver *driver;/* which driver has allocated thisdevice */void *driver_data;/* data private to the driver */void *platform_data;/* platform specific data, devicecore doesn't touch it */struct dev_pm_infopower;#ifdef config_numaint numa_node;/* numa node this device is close to */#endifu64 *dma_mask;/* dma mask (if dma'able device) */u64 coherent_dma_mask;/* like dma_mask, but foralloc_coherent mappings asnot all hardware supports64 bit addresses for consistentallocations such descriptors. */struct device_dma_parameters *dma_parms;struct list_headdma_pools;/* dma pools (if dma'ble) */struct dma_coherent_mem*dma_mem; /* internal for coherent memoverride *//* arch specific additions */struct dev_archdataarchdata;dev_t devt;/* dev_t, creates the sysfs dev */spinlock_t devres_lock;struct list_headdevres_head;struct klist_nodeknode_class;struct class *class;struct attribute_group**groups;/* optional groups */void (*release)(struct device *dev);};
可以看出device结构体中也包含了一个kobject对象
intdevice_register(struct device *dev);
注册设备
vioddevice_unregister(struct device *dev)
注销设备
设备属性由struct device_attribute描述
structdevice_attribute {
struct attribute attr;
ssize_t (*show)(struct device *dev,struct device_attribute *attr,
char *buf);
ssize_t (*store)(struct device *dev,struct device_attribute *attr,
const char *buf, size_t count);
};
int device_create_file(struct device *dev, struct device_attibute *entry)
创建属性文件
void device_remove_file(struct device *dev, struct device_attibute *entry)
删除属性文件
3.驱动
驱动程序由struct device_driver描述：
structdevice_driver{
constchar*name;
structbus_type*bus;
structmodule*owner;
constchar*mod_name;/*usedforbuilt-inmodules*/
int(*probe)(structdevice*dev);
int(*remove)(structdevice*dev);
void(*shutdown)(structdevice*dev);
int(*suspend)(structdevice*dev,pm_message_tstate);
int(*resume)(structdevice*dev);
structattribute_group**groups;
structdev_pm_ops*pm;
structdriver_private*p;
};
struct 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 device *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;};
在看device_dirver的driver_private 对象
struct driver_private {
struct kobject kobj;
struct klist klist_devices;
struct klist_node knode_bus;
struct module_kobject *mkobj;
struct device_driver *driver;
};
可以看出driver_private结构体中也包含了一个kobject对象。和连接设备的链表。
当总线的match返回非0值，也就是总线找到与驱动相匹配的设备时，驱动的probe的函数将被调用。
当设备从系统总删除是remove被调用。
当系统关机的时候shutdown被调用。
int driver_register(structdevice_driver *drv)
在总线上注册驱动
void driver_unregister(struct device_driver *drv)
载总线上注销驱动
驱动的属性使用structdriver_attribute来描述
structdriver_attribute{
structattribue attr;
ssize_t(*show)(struct device_driver *drv, const char *buf);
ssize_t(*store)(struct device_driver *drv, const char *buf, size_t count);
}
int dirver_create_file(struct device_driver *drv, struct driver_attribute *attr);
创建属性文件
void driver_remove_file struct device_driver *drv, struct driver_attribute *attr);
删除属性文件
二、测试模块
1.bus
#include
#include
#include
#include
#include
module_author(davidxie);
module_license(dualbsd/gpl);
staticchar*version=$revision:1.9{1}quot;;
staticintmy_match(structdevice*dev,structdevice_driver*driver)
{
return!strncmp(dev->bus_id,driver->name,strlen(driver->name));
}
staticvoidmy_bus_release(structdevice*dev)
{
printk(kern_debugmybusrelease\n);
}
structdevicemy_bus={
.bus_id=my_bus0,
.release=my_bus_release
};
structbus_typemy_bus_type={
.name=my_bus,
.match=my_match,
};
export_symbol(my_bus);
export_symbol(my_bus_type);
/*
*exportasimpleattribute.
*/
staticssize_tshow_bus_version(structbus_type*bus,char*buf)
{
returnsnprintf(buf,page_size,%s\n,version);
}
staticbus_attr(version,s_irugo,show_bus_version,null);
staticint__initmy_bus_init(void)
{
intret;
/*注册总线*/
ret=bus_register(&my_bus_type);
if(ret)
returnret;
/*创建属性文件*/
if(bus_create_file(&my_bus_type,&bus_attr_version))
printk(kern_noticefailtocreateversionattribute!\n);
/*注册总线设备*/
ret=device_register(&my_bus);
if(ret)
printk(kern_noticefailtoregisterdevice:my_bus!\n);
returnret;
}
staticvoidmy_bus_exit(void)
{
device_unregister(&my_bus);
bus_unregister(&my_bus_type);
}
module_init(my_bus_init);
module_exit(my_bus_exit);
#include #include #include #include #include module_author(david xie);module_license(dual bsd/gpl);static char *version = $revision: 1.9 {1}quot;;static int my_match(struct device *dev, struct device_driver *driver){return !strncmp(dev->bus_id, driver->name, strlen(driver->name));}static void my_bus_release(struct device *dev){printk(kern_debug my bus release\n);}struct device my_bus = {.bus_id = my_bus0,.release = my_bus_release};struct bus_type my_bus_type = {.name = my_bus,.match = my_match,};export_symbol(my_bus);export_symbol(my_bus_type);/** export a simple attribute.*/static ssize_t show_bus_version(struct bus_type *bus, char *buf){return snprintf(buf, page_size, %s\n, version);}static bus_attr(version, s_irugo, show_bus_version, null);static int __init my_bus_init(void){int ret;/*注册总线*/ret = bus_register(&my_bus_type);if (ret)return ret;/*创建属性文件*/if (bus_create_file(&my_bus_type, &bus_attr_version))printk(kern_notice fail to create version attribute!\n);/*注册总线设备*/ret = device_register(&my_bus);if (ret)printk(kern_notice fail to register device:my_bus!\n);return ret;}static void my_bus_exit(void){device_unregister(&my_bus);bus_unregister(&my_bus_type);}module_init(my_bus_init);module_exit(my_bus_exit);
创建一条名为my_bus_type的总线和一个名为my_bus的总线设备，注意总线也是一个设备，也需要注册。
测试结果：
2.device
#include
#include
#include
#include
#include
module_author(davidxie);
module_license(dualbsd/gpl);
externstructdevicemy_bus;
externstructbus_typemy_bus_type;
/*whyneedthis?*/
staticvoidmy_dev_release(structdevice*dev)
{
}
structdevicemy_dev={
.bus=&my_bus_type,
.parent=&my_bus,
.release=my_dev_release,
};
/*
*exportasimpleattribute.
*/
staticssize_tmydev_show(structdevice*dev,char*buf)
{
returnsprintf(buf,%s\n,thisismydevice!);
}
staticdevice_attr(dev,s_irugo,mydev_show,null);
staticint__initmy_device_init(void)
{
intret=0;
/*初始化设备*/
strncpy(my_dev.bus_id,my_dev,bus_id_size);
/*注册设备*/
device_register(&my_dev);
/*创建属性文件*/
device_create_file(&my_dev,&dev_attr_dev);
returnret;
}
staticvoidmy_device_exit(void)
{
device_unregister(&my_dev);
}
module_init(my_device_init);
module_exit(my_device_exit);
#include #include #include #include #include module_author(david xie);module_license(dual bsd/gpl);extern struct device my_bus;extern struct bus_type my_bus_type;/* why need this ?*/static void my_dev_release(struct device *dev){}struct device my_dev = {.bus = &my_bus_type,.parent = &my_bus,.release = my_dev_release,};/** export a simple attribute.*/static ssize_t mydev_show(struct device *dev, char *buf){return sprintf(buf, %s\n, this is my device!);}static device_attr(dev, s_irugo, mydev_show, null);static int __init my_device_init(void){int ret = 0;/* 初始化设备 */strncpy(my_dev.bus_id, my_dev, bus_id_size);/*注册设备*/device_register(&my_dev);/*创建属性文件*/device_create_file(&my_dev, &dev_attr_dev);return ret;}static void my_device_exit(void){device_unregister(&my_dev);}module_init(my_device_init);module_exit(my_device_exit);
注册一个bus_id即名字为my_dev的设备，该设备的bus成员指向上一步创建的my_bus_type总线，parent成员指向上一步创建的my_bus总线设备。
测试结果：
3.driver
#include
#include
#include
#include
#include
module_author(davidxie);
module_license(dualbsd/gpl);
externstructbus_typemy_bus_type;
staticintmy_probe(structdevice*dev)
{
printk(driverfounddevicewhichmydrivercanhandle!\n);
return0;
}
staticintmy_remove(structdevice*dev)
{
printk(driverfounddeviceunpluged!\n);
return0;
}
structdevice_drivermy_driver={
.name=my_dev,
.bus=&my_bus_type,
.probe=my_probe,
.remove=my_remove,
};
/*
*exportasimpleattribute.
*/
staticssize_tmydriver_show(structdevice_driver*driver,char*buf)
{
returnsprintf(buf,%s\n,thisismydriver!);
}
staticdriver_attr(drv,s_irugo,mydriver_show,null);
staticint__initmy_driver_init(void)
{
intret=0;
/*注册驱动*/
driver_register(&my_driver);
/*创建属性文件*/
driver_create_file(&my_driver,&driver_attr_drv);
returnret;
}
staticvoidmy_driver_exit(void)
{
driver_unregister(&my_driver);
}
module_init(my_driver_init);
module_exit(my_driver_exit);
#include #include #include #include #include module_author(david xie);module_license(dual bsd/gpl);extern struct bus_type my_bus_type;static int my_probe(struct device *dev){printk(driver found device which my driver can handle!\n);return 0;}static int my_remove(struct device *dev){printk(driver found device unpluged!\n);return 0;}struct device_driver my_driver = {.name = my_dev,.bus = &my_bus_type,.probe = my_probe,.remove= my_remove,};/** export a simple attribute.*/static ssize_t mydriver_show(struct device_driver *driver, char *buf){return sprintf(buf, %s\n, this is my driver!);}static driver_attr(drv, s_irugo, mydriver_show, null);static int __init my_driver_init(void){int ret = 0;/*注册驱动*/driver_register(&my_driver);/*创建属性文件*/driver_create_file(&my_driver, &driver_attr_drv);return ret;}static void my_driver_exit(void){driver_unregister(&my_driver);}module_init(my_driver_init);module_exit(my_driver_exit);
创建一个名为“bus_dev”的驱动，并将bus成员指向第一步创建的my_bus_type总线
测试结果：
关于加快区块链产业发展的六条措施正式发布
近几年，我国直线马达出口数量不断减少的原因
嵌入式经典面试题
海信品质之家24日落地长沙，还要推出限量版小龙虾
用纸板制作抓娃娃机
驱动之路-设备模型之上层模型
过去十年，中国制造业升级可谓如火如荼
有源232转485转换器
亚马逊发布了其最新版本的Prime Air递送无人机
什么是分散加载文件？
三星S8/S8 Plus 于4月10日开始接受预订，售价将为人民币5824元
ToughSonic 14超声波传感器的特点优势及应用范围
音圈模组加持的3D打印血管支架已被成功研制出
数字隔离器芯片哪款默认输出低电平
智能座舱主流音频架构设计方案
RTX 3060笔记本正式上市：显卡集成3840个流处理器 支持光线追踪
积分电路的作用是什么
网络安全股悄然大热 监管机构对数据隐私要求趋严
iPhoneXSMax值不值得买
Nuro 机器人送货车将在美国德克萨斯州进行递送服务