Overview of the Character Driver Structure

Figure 15–1 shows data structures and routines that define the structure of a character device driver. Device drivers typically include the following elements:

• Device-loadable driver section

• Device configuration section

• Character driver entry points

The shaded device access section in the following figure illustrates character driver entry points.

Figure 15–1 Character Driver Roadmap

Associated with each device driver is a dev_ops(9S) structure, which in turn refers to a cb_ops(9S) structure. These structures contain pointers to the driver entry points:

• open(9E)

• close(9E)

• read(9E)

• write(9E)

• ioctl(9E)

• chpoll(9E)

• aread(9E)

• awrite(9E)

• mmap(9E)

• devmap(9E)

• segmap(9E)

• prop_op(9E)

Some of these entry points can be replaced with nodev(9F) or nulldev(9F) as appropriate.