Looking for API docs on Linux C and C++ header files

[Hal Vaughan]

I've tried searching for docs for the apis for the Linux libraries for C and
C++. I'm specifically looking for USB info (it's in /usr/include/linux/usb
for the most part).

Is there a repository somewhere with documentation on the apis in the
general headers and libs for Linux and is there a repository specifically
for the usb libraries? I don't think these libraries are part of libusb
(but could be wrong).

Thanks!

Hal