用户态应用发送消息到驱动
用户态主要代码
struct HdfIoService *serv = HdfIoServiceBind(SAMPLE_SERVICE_NAME);
......
ret = serv->dispatcher->Dispatch(&serv->object, SAMPLE_WRITE_READ, data, reply);
if (ret != HDF_SUCCESS) {
HDF_LOGE("fail to send service call");
goto out;
}
重点就是通过HdfIoServiceBind绑定服务,调用服务的Dispatch接口
HdfIoServiceBind接口流程
HdfIoServiceBind接口的主要作用是open对应服务的字符设备节点/dev/hdf/serviceName,细节流程如下:
SHELL
HdfIoServiceBind(`drivers/hdf_core/framework/core/shared/src/hdf_io_service.c`)
-> HdfIoServiceAdapterObtain
-> open /dev/hdf/serviceName
-> .Dispatch = HdfSyscallAdapterDispatch
HdfIoServiceAdapterObtain函数有两处实现:
- 针对内核态,给内核用:drivers/hdf_core/framework/core/adapter/vnode/src/hdf_vnode_adapter.c
- 针对用户态,给应用用:drivers/hdf_core/framework/core/adapter/syscall/src/hdf_syscall_adapter.c
这里主要看用户态的实现,即hdf_syscall_adapter.c
Dispatch接口流程
SHELL
serv->dispatcher->Dispatch()
dispatcher
-> Dispatch()
-> HdfSyscallAdapterDispatch
-> ioctl - HDF_WRITE_READ
最底层就是通过系统调用ioctl来读写消息(HDF_WRITE_READ)。
用户态应用接收驱动上报事件
用户态代码
struct HdfIoService *serv = HdfIoServiceBind(SAMPLE_SERVICE_NAME);
......
static struct HdfDevEventlistener listener = {
.callBack = OnDevEventReceived,
.priv ="Service0"
};
if (HdfDeviceRegisterEventListener(serv, &listener) != HDF_SUCCESS) {
HDF_LOGE("fail to register event listener");
return HDF_FAILURE;
}
主要是通过HdfDeviceRegisterEventListener注册回调函数
HdfDeviceRegisterEventListener函数流程
drivers/hdf_core/framework/core/adapter/syscall/src/hdf_syscall_adapter.c
SHELL
HdfDeviceRegisterEventListener
-> HdfDeviceRegisterEventListenerWithSchedPolicy
-> HdfIoServiceStartListen
-> HdfIoServiceThreadBindLocked
-> HdfDevListenerThreadInit
-> HdfDevListenerThreadDoInit
-> OsalThreadCreate HdfDevEventListenTask
-> HdfDevListenerThreadStart
-> HdfAdapterStartListenIoctl
-> ioctl - HDF_LISTEN_EVENT_START
-> OsalThreadStart HdfDevEventListenTask
调到最后,就是通过osal的接口OsalThreadCreate创建线程,OsalThreadStart开始线程,而对应的线程就是下面的HdfDevEventListenTask:
SHELL
HdfDevEventListenTask - poll
-> HdfDevEventReadAndDispatch
-> ioctl - HDF_READ_DEV_EVENT
-> HdfDevEventDispatchLocked
-> listener->callBack
以上的核心就是基于poll,通过ioctl来读取消息(HDF_READ_DEV_EVENT),然后再去调用上面传过来的回调函数。
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