title: dev_err() function definition
body: <p>I can see that <code>dev_*()</code> family of functions such as <code>dev_err()</code> are given as prototype in <code>include/linux/device.h</code>, but no where I could find its definition. I have visited sites like lxr.free-electrons, but without success. Used tags in the source code of linux kernel, even then failed. </p>
  
  <p>What I am trying to find is how the  <code>dev_err(const struct device *dev, const char *fmt, ...)</code> is able to get the device information such as pci bus, etc from just giving <code>const struct device *dev</code> as argument to print in logs.</p>