How can get an event on USB read

I am beginner in Embedded Linux… Can anybody help me with the starting point or references/Sample codes on to how to get events while data is available through communication peripherals , especially USB, (BTW i am working on Apalis IMX6 and IXORA carrier board)… As in my application I am trying to communicate to a GSM/GPRS Modem using USB interface.

I am aware of some functions such as poll(), epoll() , etc… but have never used them… Please help if possible

Please have a look at the man pages for poll and epoll. For GSM modems with USB interface, the following blog post might be helpful. You might also want to have a look at the polling and timing functions in libusb.