Implementing asynchronous read/write support in linux device driver

Question

I need to implement asynchronous read/write support in my linux device driver. The user space program should get a asynchronous signal from device driver, indicating that the driver has data and the user space program can read it. Below are the options i found by googling and from LDD book.

[1] Implement poll-read. The driver returns status of read/write queue. The user space program can then decide whether to perform read/write on the device.

[2] Implement async notifications. The device driver is able to send a signal to user space when data is ready on driver side. The user space program can then read the data.

However i have seen developers using select_read call with tty driver. Not sure what support should be added to my existing device driver for using select_read from user space.

Need your advice on the most efficient methods from the above.

Answer 1

Asynchronouse notifications (signals) are harder to use, so it is usually recommended to use poll() instead.

You do not need to separately implement select(), both poll() and select() are user-space interfaces that map to your driver's .poll callback in the kernel.