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<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>
!Iinclude/linux/sched.h
!Ekernel/sched.c
!Ekernel/timer.c
     </sect1>
     <sect1><title>High-resolution timers</title>
!Iinclude/linux/ktime.h
!Iinclude/linux/hrtimer.h
!Ekernel/hrtimer.c
     </sect1>
     <sect1><title>Workqueues and Kevents</title>
!Ekernel/workqueue.c
     </sect1>
     <sect1><title>Internal Functions</title>
!Ikernel/exit.c
!Ikernel/signal.c
!Iinclude/linux/kthread.h
!Ekernel/kthread.c
     </sect1>

     <sect1><title>Kernel objects manipulation</title>
<!--
X!Iinclude/linux/kobject.h
-->
!Elib/kobject.c
     </sect1>

     <sect1><title>Kernel utility functions</title>
!Iinclude/linux/kernel.h
!Ekernel/printk.c
!Ekernel/panic.c
!Ekernel/sys.c
!Ekernel/rcupdate.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>
<!-- All functions are exported at now
X!Ilib/string.c
 -->
!Elib/string.c
     </sect1>
     <sect1><title>Bit Operations</title>
!Iinclude/asm-i386/bitops.h
     </sect1>
  </chapter>

  <chapter id="kernel-lib">
     <title>Basic Kernel Library Functions</title>

     <para>
       The Linux kernel provides more basic utility functions.
     </para>

     <sect1><title>Bitmap Operations</title>
!Elib/bitmap.c
!Ilib/bitmap.c
     </sect1>

     <sect1><title>Command-line Parsing</title>
!Elib/cmdline.c
     </sect1>

     <sect1><title>CRC Functions</title>
!Elib/crc16.c
!Elib/crc32.c
!Elib/crc-ccitt.c
     </sect1>
  </chapter>

  <chapter id="mm">
     <title>Memory Management in Linux</title>
     <sect1><title>The Slab Cache</title>
!Iinclude/linux/slab.h
!Emm/slab.c
     </sect1>
     <sect1><title>User Space Memory Access</title>
!Iinclude/asm-i386/uaccess.h
!Earch/i386/lib/usercopy.c
     </sect1>
     <sect1><title>More Memory Management Functions</title>
!Iinclude/linux/rmap.h
!Emm/readahead.c
!Emm/filemap.c
!Emm/memory.c
!Emm/vmalloc.c
!Imm/page_alloc.c
!Emm/mempool.c
!Emm/page-writeback.c
!Emm/truncate.c
     </sect1>
  </chapter>


  <chapter id="ipc">
     <title>Kernel IPC facilities</title>

     <sect1><title>IPC utilities</title>
!Iipc/util.c
     </sect1>
  </chapter>

  <chapter id="kfifo">
     <title>FIFO Buffer</title>
     <sect1><title>kfifo interface</title>
!Iinclude/linux/kfifo.h
!Ekernel/kfifo.c
     </sect1>
  </chapter>

  <chapter id="relayfs">
     <title>relay interface support</title>

     <para>
	Relay interface support
	is designed to provide an efficient mechanism for tools and
	facilities to relay large amounts of data from kernel space to
	user space.
     </para>

     <sect1><title>relay interface</title>
!Ekernel/relay.c
!Ikernel/relay.c
     </sect1>
  </chapter>

  <chapter id="netcore">
     <title>Linux Networking</title>
     <sect1><title>Networking Base Types</title>
!Iinclude/linux/net.h
     </sect1>
     <sect1><title>Socket Buffer Functions</title>
!Iinclude/linux/skbuff.h
!Iinclude/net/sock.h
!Enet/socket.c
!Enet/core/skbuff.c
!Enet/core/sock.c
!Enet/core/datagram.c
!Enet/core/stream.c
     </sect1>
     <sect1><title>Socket Filter</title>
!Enet/core/filter.c
     </sect1>
     <sect1><title>Generic Network Statistics</title>
!Iinclude/linux/gen_stats.h
!Enet/core/gen_stats.c
!Enet/core/gen_estimator.c
     </sect1>
     <sect1><title>SUN RPC subsystem</title>
<!-- The !D functionality is not perfect, garbage has to be protected by comments
!Dnet/sunrpc/sunrpc_syms.c
-->
!Enet/sunrpc/xdr.c
!Enet/sunrpc/svcsock.c
!Enet/sunrpc/sched.c
     </sect1>
  </chapter>

  <chapter id="netdev">
     <title>Network device support</title>
     <sect1><title>Driver Support</title>
!Enet/core/dev.c
!Enet/ethernet/eth.c
!Iinclude/linux/etherdevice.h
!Edrivers/net/phy/phy.c
!Idrivers/net/phy/phy.c
!Edrivers/net/phy/phy_device.c
!Idrivers/net/phy/phy_device.c
!Edrivers/net/phy/mdio_bus.c
!Idrivers/net/phy/mdio_bus.c
<!-- FIXME: Removed for now since no structured comments in source
X!Enet/core/wireless.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>
        <para>
           Refer to the file kernel/module.c for more information.
        </para>
<!-- FIXME: Removed for now since no structured comments in source
X!Ekernel/module.c
-->
     </sect1>
  </chapter>

  <chapter id="hardware">
     <title>Hardware Interfaces</title>
     <sect1><title>Interrupt Handling</title>
!Ekernel/irq/manage.c
     </sect1>

     <sect1><title>DMA Channels</title>
!Ekernel/dma.c
     </sect1>

     <sect1><title>Resources Management</title>
!Ikernel/resource.c
!Ekernel/resource.c
     </sect1>

     <sect1><title>MTRR Handling</title>
!Earch/i386/kernel/cpu/mtrr/main.c
     </sect1>

     <sect1><title>PCI Support Library</title>
!Edrivers/pci/pci.c
!Edrivers/pci/pci-driver.c
!Edrivers/pci/remove.c
!Edrivers/pci/pci-acpi.c
!Edrivers/pci/search.c
!Edrivers/pci/msi.c
!Edrivers/pci/bus.c
<!-- FIXME: Removed for now since no structured comments in source
X!Edrivers/pci/hotplug.c
-->
!Edrivers/pci/probe.c
!Edrivers/pci/rom.c
     </sect1>
     <sect1><title>PCI Hotplug Support Library</title>
!Edrivers/pci/hotplug/pci_hotplug_core.c
     </sect1>
     <sect1><title>MCA Architecture</title>
	<sect2><title>MCA Device Functions</title>
           <para>
              Refer to the file arch/i386/kernel/mca.c for more information.
           </para>
<!-- FIXME: Removed for now since no structured comments in source
X!Earch/i386/kernel/mca.c
-->
	</sect2>
	<sect2><title>MCA Bus DMA</title>
!Iinclude/asm-i386/mca_dma.h
	</sect2>
     </sect1>
  </chapter>

  <chapter id="firmware">
     <title>Firmware Interfaces</title>
     <sect1><title>DMI Interfaces</title>
!Edrivers/firmware/dmi_scan.c
     </sect1>
     <sect1><title>EDD Interfaces</title>
!Idrivers/firmware/edd.c
     </sect1>
  </chapter>

  <chapter id="security">
     <title>Security Framework</title>
!Esecurity/security.c
  </chapter>

  <chapter id="audit">
     <title>Audit Interfaces</title>
!Ekernel/audit.c
!Ikernel/auditsc.c
!Ikernel/auditfilter.c
  </chapter>

  <chapter id="accounting">
     <title>Accounting Framework</title>
!Ikernel/acct.c
  </chapter>

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

  <chapter id="devdrivers">
     <title>Device drivers infrastructure</title>
     <sect1><title>Device Drivers Base</title>
<!--
X!Iinclude/linux/device.h
-->
!Edrivers/base/driver.c
!Edrivers/base/core.c
!Edrivers/base/class.c
!Edrivers/base/firmware_class.c
!Edrivers/base/transport_class.c
!Edrivers/base/dmapool.c
<!-- Cannot be included, because
     attribute_container_add_class_device_adapter
 and attribute_container_classdev_to_container
     exceed allowed 44 characters maximum
X!Edrivers/base/attribute_container.c
-->
!Edrivers/base/sys.c
<!--
X!Edrivers/base/interface.c
-->
!Edrivers/base/platform.c
!Edrivers/base/bus.c
     </sect1>
     <sect1><title>Device Drivers Power Management</title>
!Edrivers/base/power/main.c
!Edrivers/base/power/resume.c
!Edrivers/base/power/suspend.c
     </sect1>
     <sect1><title>Device Drivers ACPI Support</title>
<!-- Internal functions only
X!Edrivers/acpi/sleep/main.c
X!Edrivers/acpi/sleep/wakeup.c
X!Edrivers/acpi/motherboard.c
X!Edrivers/acpi/bus.c
-->
!Edrivers/acpi/scan.c
!Idrivers/acpi/scan.c
<!-- No correct structured comments
X!Edrivers/acpi/pci_bind.c
-->
     </sect1>
     <sect1><title>Device drivers PnP support</title>
!Edrivers/pnp/core.c
<!-- No correct structured comments
X!Edrivers/pnp/system.c
 -->
!Edrivers/pnp/card.c
!Edrivers/pnp/driver.c
!Edrivers/pnp/manager.c
!Edrivers/pnp/support.c
     </sect1>
  </chapter>

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

  <chapter id="chrdev">
	<title>Char devices</title>
!Efs/char_dev.c
  </chapter>

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

  <chapter id="parportdev">
     <title>Parallel Port Devices</title>
!Iinclude/linux/parport.h
!Edrivers/parport/ieee1284.c
!Edrivers/parport/share.c
!Idrivers/parport/daisy.c
  </chapter>

  <chapter id="message_devices">
	<title>Message-based devices</title>
     <sect1><title>Fusion message devices</title>
!Edrivers/message/fusion/mptbase.c
!Idrivers/message/fusion/mptbase.c
!Edrivers/message/fusion/mptscsih.c
!Idrivers/message/fusion/mptscsih.c
!Idrivers/message/fusion/mptctl.c
!Idrivers/message/fusion/mptspi.c
!Idrivers/message/fusion/mptfc.c
!Idrivers/message/fusion/mptlan.c
     </sect1>
     <sect1><title>I2O message devices</title>
!Iinclude/linux/i2o.h
!Idrivers/message/i2o/core.h
!Edrivers/message/i2o/iop.c
!Idrivers/message/i2o/iop.c
!Idrivers/message/i2o/config-osm.c
!Edrivers/message/i2o/exec-osm.c
!Idrivers/message/i2o/exec-osm.c
!Idrivers/message/i2o/bus-osm.c
!Edrivers/message/i2o/device.c
!Idrivers/message/i2o/device.c
!Idrivers/message/i2o/driver.c
!Idrivers/message/i2o/pci.c
!Idrivers/message/i2o/i2o_block.c
!Idrivers/message/i2o/i2o_scsi.c
!Idrivers/message/i2o/i2o_proc.c
     </sect1>
  </chapter>

  <chapter id="snddev">
     <title>Sound Devices</title>
!Iinclude/sound/core.h
!Esound/sound_core.c
!Iinclude/sound/pcm.h
!Esound/core/pcm.c
!Esound/core/device.c
!Esound/core/info.c
!Esound/core/rawmidi.c
!Esound/core/sound.c
!Esound/core/memory.c
!Esound/core/pcm_memory.c
!Esound/core/init.c
!Esound/core/isadma.c
!Esound/core/control.c
!Esound/core/pcm_lib.c
!Esound/core/hwdep.c
!Esound/core/pcm_native.c
!Esound/core/memalloc.c
<!-- FIXME: Removed for now since no structured comments in source
X!Isound/sound_firmware.c
-->
  </chapter>

  <chapter id="uart16x50">
     <title>16x50 UART Driver</title>
!Iinclude/linux/serial_core.h
!Edrivers/serial/serial_core.c
!Edrivers/serial/8250.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>
X!Edrivers/video/console/fbcon.c
     </sect1>
-->
     <sect1><title>Frame Buffer Colormap</title>
!Edrivers/video/fbcmap.c
     </sect1>
<!-- FIXME:
  drivers/video/fbgen.c has no docs, which stuffs up the sgml.  Comment
  out until somebody adds docs.  KAO
     <sect1><title>Frame Buffer Generic Functions</title>
X!Idrivers/video/fbgen.c
     </sect1>
KAO -->
     <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>
!Edrivers/video/macmodes.c
     </sect1>
     <sect1><title>Frame Buffer Fonts</title>
        <para>
           Refer to the file drivers/video/console/fonts.c for more information.
        </para>
<!-- FIXME: Removed for now since no structured comments in source
X!Idrivers/video/console/fonts.c
-->
     </sect1>
  </chapter>

  <chapter id="input_subsystem">
     <title>Input Subsystem</title>
!Iinclude/linux/input.h
!Edrivers/input/input.c
!Edrivers/input/ff-core.c
!Edrivers/input/ff-memless.c
  </chapter>

  <chapter id="spi">
      <title>Serial Peripheral Interface (SPI)</title>
  <para>
	SPI is the "Serial Peripheral Interface", widely used with
	embedded systems because it is a simple and efficient
	interface:  basically a multiplexed shift register.
	Its three signal wires hold a clock (SCK, often in the range
	of 1-20 MHz), a "Master Out, Slave In" (MOSI) data line, and
	a "Master In, Slave Out" (MISO) data line.
	SPI is a full duplex protocol; for each bit shifted out the
	MOSI line (one per clock) another is shifted in on the MISO line.
	Those bits are assembled into words of various sizes on the
	way to and from system memory.
	An additional chipselect line is usually active-low (nCS);
	four signals are normally used for each peripheral, plus
	sometimes an interrupt.
  </para>
  <para>
	The SPI bus facilities listed here provide a generalized
	interface to declare SPI busses and devices, manage them
	according to the standard Linux driver model, and perform
	input/output operations.
	At this time, only "master" side interfaces are supported,
	where Linux talks to SPI peripherals and does not implement
	such a peripheral itself.
	(Interfaces to support implementing SPI slaves would
	necessarily look different.)
  </para>
  <para>
	The programming interface is structured around two kinds of driver,
	and two kinds of device.
	A "Controller Driver" abstracts the controller hardware, which may
	be as simple as a set of GPIO pins or as complex as a pair of FIFOs
	connected to dual DMA engines on the other side of the SPI shift
	register (maximizing throughput).  Such drivers bridge between
	whatever bus they sit on (often the platform bus) and SPI, and
	expose the SPI side of their device as a
	<structname>struct spi_master</structname>.
	SPI devices are children of that master, represented as a
	<structname>struct spi_device</structname> and manufactured from
	<structname>struct spi_board_info</structname> descriptors which
	are usually provided by board-specific initialization code.
	A <structname>struct spi_driver</structname> is called a
	"Protocol Driver", and is bound to a spi_device using normal
	driver model calls.
  </para>
  <para>
	The I/O model is a set of queued messages.  Protocol drivers
	submit one or more <structname>struct spi_message</structname>
	objects, which are processed and completed asynchronously.
	(There are synchronous wrappers, however.)  Messages are
	built from one or more <structname>struct spi_transfer</structname>
	objects, each of which wraps a full duplex SPI transfer.
	A variety of protocol tweaking options are needed, because
	different chips adopt very different policies for how they
	use the bits transferred with SPI.
  </para>
!Iinclude/linux/spi/spi.h
!Fdrivers/spi/spi.c spi_register_board_info
!Edrivers/spi/spi.c
  </chapter>

</book>