<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook V3.1//EN"[]>
<book id="LinuxKernelAPI">
 <bookinfo>
  <title>The Linux Kernel API</title>
  
  <legalnotice>
   <para>
     This documentation is free software; you can redistribute
     it and/or modify it under the terms of the GNU General Public
     License as published by the Free Software Foundation; either
     version 2 of the License, or (at your option) any later
     version.
   </para>
      
   <para>
     This program is distributed in the hope that it will be
     useful, but WITHOUT ANY WARRANTY; without even the implied
     warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
     See the GNU General Public License for more details.
   </para>
      
   <para>
     You should have received a copy of the GNU General Public
     License along with this program; if not, write to the Free
     Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
     MA 02111-1307 USA
   </para>
      
   <para>
     For more details see the file COPYING in the source
     distribution of Linux.
   </para>
  </legalnotice>
 </bookinfo>

<toc></toc>

  <chapter id="Basics">
     <title>Driver Basics</title>
     <sect1><title>Driver Entry and Exit points</title>
!Iinclude/linux/init.h
     </sect1>

     <sect1><title>Atomic and pointer manipulation</title>
!Iinclude/asm-i386/atomic.h
!Iinclude/asm-i386/unaligned.h
     </sect1>

     <sect1><title>Delaying, scheduling, and timer routines</title>
!Ekernel/sched.c
     </sect1>
  </chapter>

  <chapter id="adt">
     <title>Data Types</title>
     <sect1><title>Doubly Linked Lists</title>
!Iinclude/linux/list.h
     </sect1>
  </chapter>

  <chapter id="libc">
     <title>Basic C Library Functions</title>

     <para>
       When writing drivers, you cannot in general use routines which are
       from the C Library.  Some of the functions have been found generally
       useful and they are listed below.  The behaviour of these functions
       may vary slightly from those defined by ANSI, and these deviations
       are noted in the text.
     </para>

     <sect1><title>String Conversions</title>
!Ilib/vsprintf.c
!Elib/vsprintf.c
     </sect1>
     <sect1><title>String Manipulation</title>
!Ilib/string.c
     </sect1>
     <sect1><title>Bit Operations</title>
!Iinclude/asm-i386/bitops.h
     </sect1>
  </chapter>

  <chapter id="mm">
     <title>Memory Management in Linux</title>
     <sect1><title>The Slab Cache</title>
!Emm/slab.c
      </sect1>
  </chapter>

  <chapter id="proc">
     <title>The proc filesystem</title>
 
     <sect1><title>sysctl interface</title>
!Ekernel/sysctl.c
     </sect1>
  </chapter>

  <chapter id="vfs">
     <title>The Linux VFS</title>
     <sect1><title>The Directory Cache</title>
!Efs/dcache.c
!Iinclude/linux/dcache.h
     </sect1>
     <sect1><title>Inode Handling</title>
!Efs/inode.c
!Efs/bad_inode.c
     </sect1>
     <sect1><title>Registration and Superblocks</title>
!Efs/super.c
     </sect1>
     <sect1><title>File Locks</title>
!Efs/locks.c
!Ifs/locks.c
     </sect1>
  </chapter>

  <chapter id="netcore">
     <title>Linux Networking</title>
     <sect1><title>Socket Buffer Functions</title>
!Iinclude/linux/skbuff.h
!Enet/core/skbuff.c
     </sect1>
     <sect1><title>Socket Filter</title>
!Enet/core/filter.c
     </sect1>
  </chapter>

  <chapter id="netdev">
     <title>Network device support</title>
     <sect1><title>Driver Support</title>
!Edrivers/net/net_init.c
!Enet/core/dev.c
     </sect1>
     <sect1><title>8390 Based Network Cards</title>
!Edrivers/net/8390.c
     </sect1>
     <sect1><title>Synchronous PPP</title>
!Edrivers/net/wan/syncppp.c
     </sect1>
  </chapter>

  <chapter id="modload">
     <title>Module Support</title>
     <sect1><title>Module Loading</title>
!Ekernel/kmod.c
     </sect1>
     <sect1><title>Inter Module support</title>
!Ekernel/module.c
     </sect1>
  </chapter>

  <chapter id="hardware">
     <title>Hardware Interfaces</title>
     <sect1><title>Interrupt Handling</title>
!Iarch/i386/kernel/irq.c
     </sect1>

     <sect1><title>MTRR Handling</title>
!Earch/i386/kernel/mtrr.c
     </sect1>
     <sect1><title>PCI Support Library</title>
!Edrivers/pci/pci.c
     </sect1>
     <sect1><title>PCI Hotplug Support Library</title>
!Edrivers/hotplug/pci_hotplug_core.c
!Edrivers/hotplug/pci_hotplug_util.c
     </sect1>
     <sect1><title>MCA Architecture</title>
	<sect2><title>MCA Device Functions</title>
!Earch/i386/kernel/mca.c
	</sect2>
	<sect2><title>MCA Bus DMA</title>
!Iinclude/asm-i386/mca_dma.h
	</sect2>
     </sect1>
  </chapter>

  <chapter id="devfs">
     <title>The Device File System</title>
!Efs/devfs/base.c
  </chapter>

  <chapter id="pmfuncs">
     <title>Power Management</title>
!Ekernel/pm.c
  </chapter>

  <chapter id="blkdev">
     <title>Block Devices</title>
!Edrivers/block/ll_rw_blk.c
  </chapter>

  <chapter id="miscdev">
     <title>Miscellaneous Devices</title>
!Edrivers/char/misc.c
  </chapter>

  <chapter id="viddev">
     <title>Video4Linux</title>
!Edrivers/media/video/videodev.c
  </chapter>

  <chapter id="snddev">
     <title>Sound Devices</title>
!Esound/sound_core.c
!Isound/sound_firmware.c
  </chapter>

  <chapter id="usb">
    <title>USB Devices</title>

    <para>Drivers for USB devices talk to the "usbcore" APIs, and are
    exposed through driver frameworks such as block, character,
    or network devices.
    There are two types of public "usbcore" APIs:  those intended for
    general driver use, and those which are only public to drivers that
    are part of the core.
    The drivers that are part of the core are involved in managing a USB bus.
    They include the "hub" driver, which manages trees of USB devices, and
    several different kinds of "host controller" driver (HCD), which control
    individual busses.
    </para>

    <para>The device model seen by USB drivers is relatively complex.
    </para>
     
    <itemizedlist>

	<listitem><para>USB supports four kinds of data transfer
	(control, bulk, interrupt, and isochronous).  Two transfer
	types use bandwidth as it's available (control and bulk),
	while the other two types of transfer (interrupt and isochronous)
	are scheduled to provide guaranteed bandwidth.
	</para></listitem>

	<listitem><para>The device description model includes one or more
	"configurations" per device, only one of which is active at a time.
	</para></listitem>

	<listitem><para>Configurations have one or more "interface", each
	of which may have "alternate settings".  Interfaces may be
	standardized by USB "Class" specifications, or may be specific to
	a vendor or device.</para>

	<para>USB device drivers actually bind to interfaces, not devices.
	Think of them as "interface drivers", though you
	may not see many devices where the distinction is important.
	Most USB devices are simple, with only one configuration,
	one interface, and one alternate setting.
	</para></listitem>

	<listitem><para>Interfaces have one or more "endpoints", each of
	which supports one type and direction of data transfer such as
	"bulk out" or "interrupt in".  The entire configuration may have
	up to sixteen endpoints in each direction, allocated as needed
	among all the interfaces.
	</para></listitem>

	<listitem><para>Data transfer on USB is packetized; each endpoint
	has a maximum packet size.
	Drivers must often be aware of conventions such as flagging the end
	of bulk transfers using "short" (including zero length) packets.
	</para></listitem>

	<listitem><para>The Linux USB API supports synchronous calls for
	control and bulk messaging.
	It also supports asynchnous calls for all kinds of data transfer,
	using request structures called "URBs" (USB Request Blocks).
	</para></listitem>

    </itemizedlist>

    <para>Accordingly, the USB Core API exposed to device drivers
    covers quite a lot of territory.  You'll probably need to consult
    the USB 2.0 specification, available online from www.usb.org at
    no cost, as well as class or device specifications.
    </para>

    <sect1><title>Data Types and Macros</title>
!Iinclude/linux/usb.h
    </sect1>

    <sect1><title>USB Core APIs</title>
!Edrivers/usb/core/usb.c
    </sect1>

    <sect1><title>Host Controller APIs</title>
    <para>These APIs are only for use by host controller drivers,
    most of which implement standard register interfaces such as
    EHCI, OHCI, or UHCI.
    </para>
!Edrivers/usb/core/hcd.c
    </sect1>

  </chapter>

  <chapter id="uart16x50">
     <title>16x50 UART Driver</title>
!Edrivers/char/serial.c
  </chapter>

  <chapter id="z85230">
     <title>Z85230 Support Library</title>
!Edrivers/net/wan/z85230.c
  </chapter>

  <chapter id="fbdev">
     <title>Frame Buffer Library</title>

     <para>
       The frame buffer drivers depend heavily on four data structures.  
       These structures are declared in include/linux/fb.h.  They are 
       fb_info, fb_var_screeninfo, fb_fix_screeninfo and fb_monospecs. 
       The last three can be made available to and from userland. 
     </para>

     <para>
       fb_info defines the current state of a particular video card. 
       Inside fb_info, there exists a fb_ops structure which is a 
       collection of needed functions to make fbdev and fbcon work.
       fb_info is only visible to the kernel.
     </para>

     <para>
       fb_var_screeninfo is used to describe the features of a video card 
       that are user defined.  With fb_var_screeninfo, things such as
       depth and the resolution may be defined.
     </para>

     <para>
       The next structure is fb_fix_screeninfo. This defines the 
       properties of a card that are created when a mode is set and can't 
       be changed otherwise.  A good example of this is the start of the 
       frame buffer memory.  This "locks" the address of the frame buffer
       memory, so that it cannot be changed or moved.
     </para>

     <para>
       The last structure is fb_monospecs. In the old API, there was 
       little importance for fb_monospecs. This allowed for forbidden things 
       such as setting a mode of 800x600 on a fix frequency monitor. With 
       the new API, fb_monospecs prevents such things, and if used 
       correctly, can prevent a monitor from being cooked.  fb_monospecs
       will not be useful until kernels 2.5.x.
     </para>

     <sect1><title>Frame Buffer Memory</title>
!Edrivers/video/fbmem.c
     </sect1>
     <sect1><title>Frame Buffer Console</title>
!Edrivers/video/fbcon.c
     </sect1>
     <sect1><title>Frame Buffer Colormap</title>
!Edrivers/video/fbcmap.c
     </sect1>
     <sect1><title>Frame Buffer Generic Functions</title>
!Idrivers/video/fbgen.c
     </sect1>
     <sect1><title>Frame Buffer Video Mode Database</title>
!Idrivers/video/modedb.c
!Edrivers/video/modedb.c
     </sect1>
     <sect1><title>Frame Buffer Macintosh Video Mode Database</title>
!Idrivers/video/macmodes.c
     </sect1>
     <sect1><title>Frame Buffer Fonts</title>
!Idrivers/video/fonts.c
     </sect1>
  </chapter>

</book>