SystemServer.java在服务启动时会启动UsbService（frameworks/base/services/java/com/android/server/usb/UsbService.java），UsbService会构造UsbHostManager和UsbDeviceManager
frameworks/base/services/jni/com_android_server_UsbHostManager.cpp
static void android_server_UsbHostManager_monitorUsbHostBus(JNIEnv *env, jobject thiz)
{
struct usb_host_context* context = usb_host_init();
if (!context) {
ALOGE("usb_host_init failed");
return;
}
// this will never return so it is safe to pass thiz directly
usb_host_run(context, usb_device_added, usb_device_removed, NULL, (void *)thiz);
}
system/core/libusbhost/usbhost.c
#define DEV_DIR "/dev"
#define DEV_BUS_DIR DEV_DIR "/bus"
#define USB_FS_DIR DEV_BUS_DIR "/usb"
#define USB_FS_ID_SCANNER USB_FS_DIR "/%d/%d"
#define USB_FS_ID_FORMAT USB_FS_DIR "/%03d/%03d"
#define MAX_USBFS_WD_COUNT 10
struct usb_host_context {
int fd;
usb_device_added_cb cb_added;
usb_device_removed_cb cb_removed;
void *data;
int wds[MAX_USBFS_WD_COUNT];
int wdd;
int wddbus;
};
struct usb_device {
char dev_name[64];
unsigned char desc[4096];
int desc_length;
int fd;
int writeable;
};
struct usb_host_context *usb_host_init()
{
struct usb_host_context *context = calloc(1, sizeof(struct usb_host_context));
if (!context) {
fprintf(stderr, "out of memory in usb_host_context\n");
return NULL;
}
context->fd = inotify_init();
if (context->fd < 0) {
fprintf(stderr, "inotify_init failed\n");
free(context);
return NULL;
}
return context;
}
void usb_host_run(struct usb_host_context *context,
usb_device_added_cb added_cb,
usb_device_removed_cb removed_cb,
usb_discovery_done_cb discovery_done_cb,
void *client_data)
{
int done;
done = usb_host_load(context, added_cb, removed_cb, discovery_done_cb, client_data);
while (!done) {
done = usb_host_read_event(context);
}
} /* usb_host_run() */
int usb_host_load(struct usb_host_context *context,
usb_device_added_cb added_cb,
usb_device_removed_cb removed_cb,
usb_discovery_done_cb discovery_done_cb,
void *client_data)
{
int done = 0;
int i;
context->cb_added = added_cb;
context->cb_removed = removed_cb;
context->data = client_data;
D("Created device discovery thread\n");
/* watch for files added and deleted within USB_FS_DIR */
context->wddbus = -1;
for (i = 0; i < MAX_USBFS_WD_COUNT; i++)
context->wds[i] = -1;
/* watch the root for new subdirectories */
context->wdd = inotify_add_watch(context->fd, DEV_DIR, IN_CREATE | IN_DELETE);
if (context->wdd < 0) {
fprintf(stderr, "inotify_add_watch failed\n");
if (discovery_done_cb)
discovery_done_cb(client_data);
return done;
}
watch_existing_subdirs(context, context->wds, MAX_USBFS_WD_COUNT);
/* check for existing devices first, after we have inotify set up */
done = find_existing_devices(added_cb, client_data);
if (discovery_done_cb)
done |= discovery_done_cb(client_data);
return done;
} /* usb_host_load() */
static void watch_existing_subdirs(struct usb_host_context *context,
int *wds, int wd_count)
{
char path[100];
int i, ret;
wds[0] = inotify_add_watch(context->fd, USB_FS_DIR, IN_CREATE | IN_DELETE);
if (wds[0] < 0)
return;
/* watch existing subdirectories of USB_FS_DIR */
for (i = 1; i < wd_count; i++) {
snprintf(path, sizeof(path), USB_FS_DIR "/%03d", i);
ret = inotify_add_watch(context->fd, path, IN_CREATE | IN_DELETE);
if (ret >= 0)
wds[i] = ret;
}
}
/* returns true if one of the callbacks indicates we are done */
static int find_existing_devices(usb_device_added_cb added_cb,
void *client_data)
{
char busname[32];
DIR *busdir;
struct dirent *de;
int done = 0;
busdir = opendir(USB_FS_DIR);
if(busdir == 0) return 0;
while ((de = readdir(busdir)) != 0 && !done) {
if(badname(de->d_name)) continue;
snprintf(busname, sizeof(busname), USB_FS_DIR "/%s", de->d_name);
done = find_existing_devices_bus(busname, added_cb,
client_data);
} //end of busdir while
closedir(busdir);
return done;
}
static int find_existing_devices_bus(char *busname,
usb_device_added_cb added_cb,
void *client_data)
{
char devname[32];
DIR *devdir;
struct dirent *de;
int done = 0;
devdir = opendir(busname);
if(devdir == 0) return 0;
while ((de = readdir(devdir)) && !done) {
if(badname(de->d_name)) continue;
snprintf(devname, sizeof(devname), "%s/%s", busname, de->d_name);
done = added_cb(devname, client_data);
} // end of devdir while
closedir(devdir);
return done;
}
static int usb_device_added(const char *devname, void* client_data) {
struct usb_descriptor_header* desc;
struct usb_descriptor_iter iter;
struct usb_device *device = usb_device_open(devname);
if (!device) {
ALOGE("usb_device_open failed\n");
return 0;
}
JNIEnv* env = AndroidRuntime::getJNIEnv();
jobject thiz = (jobject)client_data;
Vector<int> interfaceValues;
Vector<int> endpointValues;
const usb_device_descriptor* deviceDesc = usb_device_get_device_descriptor(device);
uint16_t vendorId = usb_device_get_vendor_id(device);
uint16_t productId = usb_device_get_product_id(device);
uint8_t deviceClass = deviceDesc->bDeviceClass;
uint8_t deviceSubClass = deviceDesc->bDeviceSubClass;
uint8_t protocol = deviceDesc->bDeviceProtocol;
usb_descriptor_iter_init(device, &iter);
while ((desc = usb_descriptor_iter_next(&iter)) != NULL) {
if (desc->bDescriptorType == USB_DT_INTERFACE) {
struct usb_interface_descriptor *interface = (struct usb_interface_descriptor *)desc;
// push class, subclass, protocol and number of endpoints into interfaceValues vector
interfaceValues.add(interface->bInterfaceNumber);
interfaceValues.add(interface->bInterfaceClass);
interfaceValues.add(interface->bInterfaceSubClass);
interfaceValues.add(interface->bInterfaceProtocol);
interfaceValues.add(interface->bNumEndpoints);
} else if (desc->bDescriptorType == USB_DT_ENDPOINT) {
struct usb_endpoint_descriptor *endpoint = (struct usb_endpoint_descriptor *)desc;
// push address, attributes, max packet size and interval into endpointValues vector
endpointValues.add(endpoint->bEndpointAddress);
endpointValues.add(endpoint->bmAttributes);
endpointValues.add(__le16_to_cpu(endpoint->wMaxPacketSize));
endpointValues.add(endpoint->bInterval);
}
}
usb_device_close(device);
// handle generic device notification
int length = interfaceValues.size();
jintArray interfaceArray = env->NewIntArray(length);
env->SetIntArrayRegion(interfaceArray, 0, length, interfaceValues.array());
length = endpointValues.size();
jintArray endpointArray = env->NewIntArray(length);
env->SetIntArrayRegion(endpointArray, 0, length, endpointValues.array());
jstring deviceName = env->NewStringUTF(devname);
env->CallVoidMethod(thiz, method_usbDeviceAdded,
deviceName, vendorId, productId, deviceClass,
deviceSubClass, protocol, interfaceArray, endpointArray);
env->DeleteLocalRef(interfaceArray);
env->DeleteLocalRef(endpointArray);
env->DeleteLocalRef(deviceName);
checkAndClearExceptionFromCallback(env, __FUNCTION__);
return 0;
}
frameworks/base/services/java/com/android/server/usb/UsbHostManager.java
/* Called from JNI in monitorUsbHostBus() to report new USB devices */
private void usbDeviceAdded(String deviceName, int vendorID, int productID,
int deviceClass, int deviceSubclass, int deviceProtocol,
/* array of quintuples containing id, class, subclass, protocol
and number of endpoints for each interface */
int[] interfaceValues,
/* array of quadruples containing address, attributes, max packet size
and interval for each endpoint */
int[] endpointValues) {
if (isBlackListed(deviceName) ||
isBlackListed(deviceClass, deviceSubclass, deviceProtocol)) {
return;
}
synchronized (mLock) {
if (mDevices.get(deviceName) != null) {
Slog.w(TAG, "device already on mDevices list: " + deviceName);
return;
}
int numInterfaces = interfaceValues.length / 5;
Parcelable[] interfaces = new UsbInterface[numInterfaces];
try {
// repackage interfaceValues as an array of UsbInterface
int intf, endp, ival = 0, eval = 0;
for (intf = 0; intf < numInterfaces; intf++) {
int interfaceId = interfaceValues[ival++];
int interfaceClass = interfaceValues[ival++];
int interfaceSubclass = interfaceValues[ival++];
int interfaceProtocol = interfaceValues[ival++];
int numEndpoints = interfaceValues[ival++];
Parcelable[] endpoints = new UsbEndpoint[numEndpoints];
for (endp = 0; endp < numEndpoints; endp++) {
int address = endpointValues[eval++];
int attributes = endpointValues[eval++];
int maxPacketSize = endpointValues[eval++];
int interval = endpointValues[eval++];
endpoints[endp] = new UsbEndpoint(address, attributes,
maxPacketSize, interval);
}
// don't allow if any interfaces are blacklisted
if (isBlackListed(interfaceClass, interfaceSubclass, interfaceProtocol)) {
return;
}
interfaces[intf] = new UsbInterface(interfaceId, interfaceClass,
interfaceSubclass, interfaceProtocol, endpoints);
}
} catch (Exception e) {
// beware of index out of bound exceptions, which might happen if
// a device does not set bNumEndpoints correctly
Slog.e(TAG, "error parsing USB descriptors", e);
return;
}
UsbDevice device = new UsbDevice(deviceName, vendorID, productID,
deviceClass, deviceSubclass, deviceProtocol, interfaces);
mDevices.put(deviceName, device);
getCurrentSettings().deviceAttached(device);
}
}
frameworks/base/services/java/com/android/server/usb/UsbSettingsManager.java
public void deviceAttached(UsbDevice device) {
Intent intent = new Intent(UsbManager.ACTION_USB_DEVICE_ATTACHED);
intent.putExtra(UsbManager.EXTRA_DEVICE, device);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
ArrayList<ResolveInfo> matches;
String defaultPackage;
synchronized (mLock) {
matches = getDeviceMatchesLocked(device, intent);
// Launch our default activity directly, if we have one.
// Otherwise we will start the UsbResolverActivity to allow the user to choose.
defaultPackage = mDevicePreferenceMap.get(new DeviceFilter(device));
}
// Send broadcast to running activity with registered intent
mUserContext.sendBroadcast(intent);
// Start activity with registered intent
resolveActivity(intent, matches, defaultPackage, device, null);
}