我現在有一個可用的Mac驅動程序到需要通過中斷端點進行通信的USB設備。以下是我的做法：
最終，對我而言效果最好的方法是選項1（如上所述）。如上所述，我在向設備打開COM樣式的IOUSBInterfaceInterface時遇到了問題。隨着時間的推移，很明顯這是由於HIDManager捕獲設備造成的。一旦捕獲到設備（即使USBInterfaceOpenSeize調用或USBDeviceOpenSeize調用不起作用），我也無法從HIDManager控制設備。
要控制設備，我需要在HIDManager之前抓住它。解決方案是編寫無代碼kext（內核擴展）。kext基本上是一個包含在System/Library/Extensions中的包，通常包含plist（屬性列表）和（有時）內核級驅動程序等。在我的情況下，我只想要plist，它會向內核提供與它匹配的設備的說明。如果數據比HIDManager提供更高的探測分數，那麼我基本上可以捕獲設備並使用用戶空間驅動程序與其通信。
的內核擴展的plist寫着字，用修改了一些項目的具體細節，如下：
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>OSBundleLibraries</key>
<dict>
<key>com.apple.iokit.IOUSBFamily</key>
<string>1.8</string>
<key>com.apple.kernel.libkern</key>
<string>6.0</string>
</dict>
<key>CFBundleDevelopmentRegion</key>
<string>English</string>
<key>CFBundleGetInfoString</key>
<string>Demi USB Device</string>
<key>CFBundleIdentifier</key>
<string>com.demiart.mydevice</string>
<key>CFBundleInfoDictionaryVersion</key>
<string>6.0</string>
<key>CFBundleName</key>
<string>Demi USB Device</string>
<key>CFBundlePackageType</key>
<string>KEXT</string>
<key>CFBundleSignature</key>
<string>????</string>
<key>CFBundleVersion</key>
<string>1.0.0</string>
<key>IOKitPersonalities</key>
<dict>
<key>Device Driver</key>
<dict>
<key>CFBundleIdentifier</key>
<string>com.apple.kernel.iokit</string>
<key>IOClass</key>
<string>IOService</string>
<key>IOProviderClass</key>
<string>IOUSBInterface</string>
<key>idProduct</key>
<integer>12345</integer>
<key>idVendor</key>
<integer>67890</integer>
<key>bConfigurationValue</key>
<integer>1</integer>
<key>bInterfaceNumber</key>
<integer>0</integer>
</dict>
</dict>
<key>OSBundleRequired</key>
<string>Local-Root</string>
</dict>
</plist>
的idVendor和idProduct值給出的kext特異性和充分提高其探測積分。
爲了使用KEXT，下面的事情需要做（這我的安裝程序會爲客戶做）：
- 更改所有者根：車輪（
sudo chown root:wheel DemiUSBDevice.kext）
- 複製KEXT以擴展（
sudo cp DemiUSBDevice.kext /System/Library/Extensions）
- 調用kextload實用程序加載立即使用的kext不重新啓動（
sudo kextload -vt /System/Library/Extensions/DemiUSBDevice.kext）
- 觸摸擴展文件夾，以便下一次重啓將強制緩存重建（
sudo touch /System/Library/Extensions）
此時系統應該使用kext保持HIDManager無法捕獲我的設備。現在，該怎麼辦？如何寫入和讀取它？
以下是我的代碼的簡化片段，減去任何錯誤處理，說明解決方案。在能夠對設備進行任何操作之前，應用程序需要知道設備何時附着（和分離）。請注意，這僅僅是爲了說明目的 - 一些變量是類級別的，有些是全球性的，等這裏是初始化代碼，設置安裝/拆卸活動起來：
#include <IOKit/IOKitLib.h>
#include <IOKit/IOCFPlugIn.h>
#include <IOKit/usb/IOUSBLib.h>
#include <mach/mach.h>
#define DEMI_VENDOR_ID 12345
#define DEMI_PRODUCT_ID 67890
void DemiUSBDriver::initialize(void)
{
IOReturn result;
Int32 vendor_id = DEMI_VENDOR_ID;
Int32 product_id = DEMI_PRODUCT_ID;
mach_port_t master_port;
CFMutableDictionaryRef matching_dict;
IONotificationPortRef notify_port;
CFRunLoopSourceRef run_loop_source;
//create a master port
result = IOMasterPort(bootstrap_port, &master_port);
//set up a matching dictionary for the device
matching_dict = IOServiceMatching(kIOUSBDeviceClassName);
//add matching parameters
CFDictionarySetValue(matching_dict, CFSTR(kUSBVendorID),
CFNumberCreate(kCFAllocatorDefault, kCFNumberInt32Type, &vendor_id));
CFDictionarySetValue(matching_dict, CFSTR(kUSBProductID),
CFNumberCreate(kCFAllocatorDefault, kCFNumberInt32Type, &product_id));
//create the notification port and event source
notify_port = IONotificationPortCreate(master_port);
run_loop_source = IONotificationPortGetRunLoopSource(notify_port);
CFRunLoopAddSource(CFRunLoopGetCurrent(), run_loop_source,
kCFRunLoopDefaultMode);
//add an additional reference for a secondary event
// - each consumes a reference...
matching_dict = (CFMutableDictionaryRef)CFRetain(matching_dict);
//add a notification callback for detach event
//NOTE: removed_iter is a io_iterator_t, declared elsewhere
result = IOServiceAddMatchingNotification(notify_port,
kIOTerminatedNotification, matching_dict, device_detach_callback,
NULL, &removed_iter);
//call the callback to 'arm' the notification
device_detach_callback(NULL, removed_iter);
//add a notification callback for attach event
//NOTE: added_iter is a io_iterator_t, declared elsewhere
result = IOServiceAddMatchingNotification(notify_port,
kIOFirstMatchNotification, matching_dict, device_attach_callback,
NULL, &g_added_iter);
if (result)
{
throw Exception("Unable to add attach notification callback.");
}
//call the callback to 'arm' the notification
device_attach_callback(NULL, added_iter);
//'pump' the run loop to handle any previously added devices
service();
}
有兩種方法在初始化代碼中用作回調：device_detach_callback和device_attach_callback（均在靜態方法中聲明）。 device_detach_callback很簡單：
//implementation
void DemiUSBDevice::device_detach_callback(void* context, io_iterator_t iterator)
{
IOReturn result;
io_service_t obj;
while ((obj = IOIteratorNext(iterator)))
{
//close all open resources associated with this service/device...
//release the service
result = IOObjectRelease(obj);
}
}
device_attach_callback是大部分魔術發生的地方。在我的代碼，我有這個分爲多種方法，但在這裏我將介紹它作爲一個大整體的方法...：
void DemiUSBDevice::device_attach_callback(void * context,
io_iterator_t iterator)
{
IOReturn result;
io_service_t usb_service;
IOCFPlugInInterface** plugin;
HRESULT hres;
SInt32 score;
UInt16 vendor;
UInt16 product;
IOUSBFindInterfaceRequest request;
io_iterator_t intf_iterator;
io_service_t usb_interface;
UInt8 interface_endpoint_count = 0;
UInt8 pipe_ref = 0xff;
UInt8 direction;
UInt8 number;
UInt8 transfer_type;
UInt16 max_packet_size;
UInt8 interval;
CFRunLoopSourceRef m_event_source;
CFRunLoopSourceRef compl_event_source;
IOUSBDeviceInterface245** dev = NULL;
IOUSBInterfaceInterface245** intf = NULL;
while ((usb_service = IOIteratorNext(iterator)))
{
//create the intermediate plugin
result = IOCreatePlugInInterfaceForService(usb_service,
kIOUSBDeviceUserClientTypeID, kIOCFPlugInInterfaceID, &plugin,
&score);
//get the device interface
hres = (*plugin)->QueryInterface(plugin,
CFUUIDGetUUIDBytes(kIOUSBDeviceInterfaceID245), (void**)&dev);
//release the plugin - no further need for it
IODestroyPlugInInterface(plugin);
//double check ids for correctness
result = (*dev)->GetDeviceVendor(dev, &vendor);
result = (*dev)->GetDeviceProduct(dev, &product);
if ((vendor != DEMI_VENDOR_ID) || (product != DEMI_PRODUCT_ID))
{
continue;
}
//set up interface find request
request.bInterfaceClass = kIOUSBFindInterfaceDontCare;
request.bInterfaceSubClass = kIOUSBFindInterfaceDontCare;
request.bInterfaceProtocol = kIOUSBFindInterfaceDontCare;
request.bAlternateSetting = kIOUSBFindInterfaceDontCare;
result = (*dev)->CreateInterfaceIterator(dev, &request, &intf_iterator);
while ((usb_interface = IOIteratorNext(intf_iterator)))
{
//create intermediate plugin
result = IOCreatePlugInInterfaceForService(usb_interface,
kIOUSBInterfaceUserClientTypeID, kIOCFPlugInInterfaceID, &plugin,
&score);
//release the usb interface - not needed
result = IOObjectRelease(usb_interface);
//get the general interface interface
hres = (*plugin)->QueryInterface(plugin, CFUUIDGetUUIDBytes(
kIOUSBInterfaceInterfaceID245), (void**)&intf);
//release the plugin interface
IODestroyPlugInInterface(plugin);
//attempt to open the interface
result = (*intf)->USBInterfaceOpen(intf);
//check that the interrupt endpoints are available on this interface
//calling 0xff invalid...
m_input_pipe = 0xff; //UInt8, pipe from device to Mac
m_output_pipe = 0xff; //UInt8, pipe from Mac to device
result = (*intf)->GetNumEndpoints(intf, &interface_endpoint_count);
if (!result)
{
//check endpoints for direction, type, etc.
//note that pipe_ref == 0 is the control endpoint (we don't want it)
for (pipe_ref = 1; pipe_ref <= interface_endpoint_count; pipe_ref++)
{
result = (*intf)->GetPipeProperties(intf, pipe_ref, &direction,
&number, &transfer_type, &max_packet_size, &interval);
if (result)
{
break;
}
if (transfer_type == kUSBInterrupt)
{
if (direction == kUSBIn)
{
m_input_pipe = pipe_ref;
}
else if (direction == kUSBOut)
{
m_output_pipe = pipe_ref;
}
}
}
}
//set up async completion notifications
result = (*m_intf)->CreateInterfaceAsyncEventSource(m_intf,
&compl_event_source);
CFRunLoopAddSource(CFRunLoopGetCurrent(), compl_event_source,
kCFRunLoopDefaultMode);
break;
}
break;
}
}
在這一點上，我們應該有中斷端點的數量和開放IOUSBInterfaceInterface到設備。數據的異步寫入可以通過調用像這樣做：
result = (intf)->WritePipeAsync(intf, m_output_pipe,
data, OUTPUT_DATA_BUF_SZ, device_write_completion,
NULL);
，其中數據是寫的字符緩衝區，最後一個參數是一個可選的上下文對象傳遞給回調函數，並device_write_completion是一個靜態方法具有以下一般形式：
void DemiUSBDevice::device_write_completion(void* context,
IOReturn result, void* arg0)
{
//...
}
從中斷端點讀取是相似的：
result = (intf)->ReadPipeAsync(intf, m_input_pipe,
data, INPUT_DATA_BUF_SZ, device_read_completion,
NULL);
其中device_read_completi在如下形式：
void DemiUSBDevice::device_read_completion(void* context,
IOReturn result, void* arg0)
{
//...
}
注意，要接收這些回調的運行循環必須運行（see this link for more information about the CFRunLoop）。達到此目的的一種方法是在調用異步讀取或寫入方法後調用CFRunLoopRun()，此時主線程在運行循環運行時阻塞。處理完回叫後，您可以撥打CFRunLoopStop(CFRunLoopGetCurrent())停止運行循環並將執行回執至主線程。
另一個替代方案（我在我的代碼中做的）是將一個上下文對象（在下面的代碼示例中名爲'request'）傳遞給WritePipeAsync/ReadPipeAsync方法 - 該對象包含一個布爾完成標誌（名爲'is_done'在這個例子中）。調用讀/寫方法，而不是調用CFRunLoopRun()後，像下面這樣可以執行：
while (!(request->is_done))
{
//run for 1/10 second to handle events
Boolean returnAfterSourceHandled = false;
CFTimeInterval seconds = 0.1;
CFStringRef mode = kCFRunLoopDefaultMode;
CFRunLoopRunInMode(mode, seconds, returnAfterSourceHandled);
}
這樣做的好處是，如果你有使用運行循環，你不會過早退出應其他線程另一個線程停止運行環...
我希望這是有幫助的人。我不得不從許多來源不全拉來解決這個問題，這需要大量的工作來獲得運行良好......
+1。 +100這個答案很棒，我非常感謝你的辛勤工作。 – TarkaDaal 2014-05-08 09:50:27