You should look at
LWN. It's a news site maintained by Jonathan Corbet, who co-authored the popular 'Linux Device Drivers' books for 2.4 and 2.6 kernels, and maintains a weekly newsletter about what currently happens in the Linux community. It also maintains archives, which gives it an
index covering the widest range of topics in the Linux kernel.
You can read the 2.6 driver book on LWN as a starter, as there is no radical departure between Linux 3.x and the 2.6.x series. You can even grab an older copy/branch of the kernel like 2.6.32 and run it in a VM, as then there will be no difference between the source you use and what the existing books contain.