PCI BUS and PCI DEVICES:
------------------------
System boot process - Device discovery
General device characteristics -
	Device Registers
	Device access - Device Memory - DMA and Programmed I/O
	Device Interrupts

Other buses and devices:
------------------------
USB
SCSI

Device Tree
--------------
* Bus Nexus and leaf devices [ Differences in driver functionalities for each ]
* prtconf - Parent  - Child relation ships
* /devices and devfs

DDI/DKI main functions :
----------------------------

* Dynamic loading and unloading of modules
* Interrupt handling
* Accessing the device space from the kernel or a user process, that is, 
  register mapping and memory mapping
* Accessing kernel or user process space from the device using DMA services
* Managing device properties
* Power management

Driver attaching
-----------------
* Creation of device properties :
	- Device aliases for attaching drivers to devices.
	- Other properties specific to the device
	- property access functions

* /etc/driver_aliases - Repository of drivers and hardware they are 
                        responsible for.

Autoconfiguration
------------------
* modlinkage -> modldrv-> devops -> cbops

   mod_install is a commn interface for all kinds of modules.
   Module specific initialisation is done by the modm_ routines in mod_ops

* modldrv -> mod_driverops, which is a defined structure used for driver 
             modules.  (refer uts/os/modconf.c)
   mod_ops -> uts/common/sys/modctl.h

   _init -> mod_install.
   _fini
   _info

Attach and detach
------------------

Things to do during attach :
* Allocating a soft-state structure for the device instance
* Initializing per-instance mutexes
* Initializing condition variables
* Registering the device s interrupts
* Mapping the registers and memory of the device instance
* Creating minor device nodes for the device instance
* Reporting that the device instance has attached

Things to do during detach :
-----------------------------
Reversal of all operations done in attach


Accessing device/device memory :
-----------------------------------
PCI config space
ddi_regs_map_setup


Interrupt handling
----------------------
check for hi level interrupts
check for number of interrupts
get the iblock cookie for an interrupt specification
initialise mutexes with the iblock cookie
add the interrupt handler

References:
-----------

* Writing Device Drivers:
  http://docs.sun.com/app/docs/doc/816-4854

* From "man -s9e intro"

   How to Use Section 9
      Section 9 is divided into the following subsections:

      9E       Driver Entry Points - contains reference pages  for
               all driver entry point routines.

      9F       Kernel Functions - contains reference pages for all
               driver support routines.

      9P       Driver Properties - contains  reference  pages  for
               driver properties.

      9S       Data Structures  -  contains  reference  pages  for
               driver-related structures.

* A discussion on nexus drivers on the device drivers mailing list on
  opensolaris.org:
  http://www.opensolaris.org/jive/thread.jspa?threadID=16207