Merge with /pub/scm/linux/kernel/git/torvalds/linux-2.6.git

S: USA

N: Dave Neuer

E: dneuer@innovation-charter.com

E: mr_fred_smoothie@yahoo.com

E: dave.neuer@pobox.com

D: Helped implement support for Compaq's H31xx series iPAQs

D: Other mostly minor tweaks & bugfixes

S: 325 E. Main St., Suite 3

S: Carnegie, PA 15105

S: USA

N: Michael Neuffer

E: mike@i-Connect.Net

DOCBOOKS := wanbook.xml z8530book.xml mcabook.xml videobook.xml \

	    kernel-hacking.xml kernel-locking.xml deviceiobook.xml \

	    procfs-guide.xml writing_usb_driver.xml scsidrivers.xml \

	    procfs-guide.xml writing_usb_driver.xml \

	    sis900.xml kernel-api.xml journal-api.xml lsm.xml usb.xml \

	    gadget.xml libata.xml mtdnand.xml librs.xml

X!Iinclude/linux/device.h

-->

!Edrivers/base/driver.c

!Edrivers/base/class_simple.c

!Edrivers/base/core.c

!Edrivers/base/firmware_class.c

!Edrivers/base/transport_class.c

  </authorgroup>

  <copyright>

   <year>2003</year>

   <year>2003-2005</year>

   <holder>Jeff Garzik</holder>

  </copyright>

<toc></toc>

  <chapter id="libataThanks">

     <title>Thanks</title>

  <para>

  The bulk of the ATA knowledge comes thanks to long conversations with

  Andre Hedrick (www.linux-ide.org).

  </para>

  <chapter id="libataIntroduction">

     <title>Introduction</title>

  <para>

  Thanks to Alan Cox for pointing out similarities 

  between SATA and SCSI, and in general for motivation to hack on

  libata.

  libATA is a library used inside the Linux kernel to support ATA host

  controllers and devices.  libATA provides an ATA driver API, class

  transports for ATA and ATAPI devices, and SCSI<->ATA translation

  for ATA devices according to the T10 SAT specification.

  </para>

  <para>

  libata's device detection

  method, ata_pio_devchk, and in general all the early probing was

  based on extensive study of Hale Landis's probe/reset code in his

  ATADRVR driver (www.ata-atapi.com).

  This Guide documents the libATA driver API, library functions, library

  internals, and a couple sample ATA low-level drivers.

  </para>

  </chapter>

  <chapter id="libataDriverApi">

     <title>libata Driver API</title>

     <para>

     struct ata_port_operations is defined for every low-level libata

     hardware driver, and it controls how the low-level driver

     interfaces with the ATA and SCSI layers.

     </para>

     <para>

     FIS-based drivers will hook into the system with ->qc_prep() and

     ->qc_issue() high-level hooks.  Hardware which behaves in a manner

     similar to PCI IDE hardware may utilize several generic helpers,

     defining at a bare minimum the bus I/O addresses of the ATA shadow

     register blocks.

     </para>

     <sect1>

        <title>struct ata_port_operations</title>

	<sect2><title>Disable ATA port</title>

	<programlisting>

void (*port_disable) (struct ata_port *);

	</programlisting>

	unplug).

	</para>

	</sect2>

	<sect2><title>Post-IDENTIFY device configuration</title>

	<programlisting>

void (*dev_config) (struct ata_port *, struct ata_device *);

	</programlisting>

	issue of SET FEATURES - XFER MODE, and prior to operation.

	</para>

	</sect2>

	<sect2><title>Set PIO/DMA mode</title>

	<programlisting>

void (*set_piomode) (struct ata_port *, struct ata_device *);

void (*set_dmamode) (struct ata_port *, struct ata_device *);

	->set_dma_mode() is only called if DMA is possible.

	</para>

	</sect2>

	<sect2><title>Taskfile read/write</title>

	<programlisting>

void (*tf_load) (struct ata_port *ap, struct ata_taskfile *tf);

void (*tf_read) (struct ata_port *ap, struct ata_taskfile *tf);

	taskfile register values.

	</para>

	</sect2>

	<sect2><title>ATA command execute</title>

	<programlisting>

void (*exec_command)(struct ata_port *ap, struct ata_taskfile *tf);

	</programlisting>

	->tf_load(), to be initiated in hardware.

	</para>

	</sect2>

	<sect2><title>Per-cmd ATAPI DMA capabilities filter</title>

	<programlisting>

int (*check_atapi_dma) (struct ata_queued_cmd *qc);

	</programlisting>

	<para>

Allow low-level driver to filter ATA PACKET commands, returning a status

indicating whether or not it is OK to use DMA for the supplied PACKET

command.

	</para>

	</sect2>

	<sect2><title>Read specific ATA shadow registers</title>

	<programlisting>

u8   (*check_status)(struct ata_port *ap);

void (*dev_select)(struct ata_port *ap, unsigned int device);

u8   (*check_altstatus)(struct ata_port *ap);

u8   (*check_err)(struct ata_port *ap);

	</programlisting>

	<para>

	Reads the Status ATA shadow register from hardware.  On some

	hardware, this has the side effect of clearing the interrupt

	condition.

	Reads the Status/AltStatus/Error ATA shadow register from

	hardware.  On some hardware, reading the Status register has

	the side effect of clearing the interrupt condition.

	</para>

	</sect2>

	<sect2><title>Select ATA device on bus</title>

	<programlisting>

void (*dev_select)(struct ata_port *ap, unsigned int device);

	</programlisting>

	<para>

	Issues the low-level hardware command(s) that causes one of N

	hardware devices to be considered 'selected' (active and

	available for use) on the ATA bus.

	available for use) on the ATA bus.  This generally has no

meaning on FIS-based devices.

	</para>

	</sect2>

	<sect2><title>Reset ATA bus</title>

	<programlisting>

void (*phy_reset) (struct ata_port *ap);

	</programlisting>

	functions ata_bus_reset() or sata_phy_reset() for this hook.

	</para>

	</sect2>

	<sect2><title>Control PCI IDE BMDMA engine</title>

	<programlisting>

void (*bmdma_setup) (struct ata_queued_cmd *qc);

void (*bmdma_start) (struct ata_queued_cmd *qc);

void (*bmdma_stop) (struct ata_port *ap);

u8   (*bmdma_status) (struct ata_port *ap);

	</programlisting>

	<para>

When setting up an IDE BMDMA transaction, these hooks arm

	(->bmdma_setup) and fire (->bmdma_start) the hardware's DMA

	engine.

(->bmdma_setup), fire (->bmdma_start), and halt (->bmdma_stop)

the hardware's DMA engine.  ->bmdma_status is used to read the standard

PCI IDE DMA Status register.

	</para>

	<para>

These hooks are typically either no-ops, or simply not implemented, in

FIS-based drivers.

	</para>

	</sect2>

	<sect2><title>High-level taskfile hooks</title>

	<programlisting>

void (*qc_prep) (struct ata_queued_cmd *qc);

int (*qc_issue) (struct ata_queued_cmd *qc);

	->qc_issue is used to make a command active, once the hardware

	and S/G tables have been prepared.  IDE BMDMA drivers use the

	helper function ata_qc_issue_prot() for taskfile protocol-based

	dispatch.  More advanced drivers roll their own ->qc_issue

	implementation, using this as the "issue new ATA command to

	hardware" hook.

	dispatch.  More advanced drivers implement their own ->qc_issue.

	</para>

	</sect2>

	<sect2><title>Timeout (error) handling</title>

	<programlisting>

void (*eng_timeout) (struct ata_port *ap);

	</programlisting>

	<para>

This is a high level error handling function, called from the

	error handling thread, when a command times out.

error handling thread, when a command times out.  Most newer

hardware will implement its own error handling code here.  IDE BMDMA

drivers may use the helper function ata_eng_timeout().

	</para>

	</sect2>

	<sect2><title>Hardware interrupt handling</title>

	<programlisting>

irqreturn_t (*irq_handler)(int, void *, struct pt_regs *);

void (*irq_clear) (struct ata_port *);

	is quiet.

	</para>

	</sect2>

	<sect2><title>SATA phy read/write</title>

	<programlisting>

u32 (*scr_read) (struct ata_port *ap, unsigned int sc_reg);

void (*scr_write) (struct ata_port *ap, unsigned int sc_reg,

	if ->phy_reset hook called the sata_phy_reset() helper function.

	</para>

	</sect2>

	<sect2><title>Init and shutdown</title>

	<programlisting>

int (*port_start) (struct ata_port *ap);

void (*port_stop) (struct ata_port *ap);

	tasks.  

	</para>

	<para>

	->host_stop() is called when the rmmod or hot unplug process

	begins.  The hook must stop all hardware interrupts, DMA

	engines, etc.

	</para>

	<para>

	->port_stop() is called after ->host_stop().  It's sole function

	is to release DMA/memory resources, now that they are no longer

	actively being used.

	</para>

	<para>

	->host_stop() is called after all ->port_stop() calls

have completed.  The hook must finalize hardware shutdown, release DMA

and other resources, etc.

	</para>

	</sect2>

     </sect1>

  </chapter>

!Idrivers/scsi/sata_sil.c

  </chapter>

  <chapter id="libataThanks">

     <title>Thanks</title>

  <para>

  The bulk of the ATA knowledge comes thanks to long conversations with

  Andre Hedrick (www.linux-ide.org), and long hours pondering the ATA

  and SCSI specifications.

  </para>

  <para>

  Thanks to Alan Cox for pointing out similarities 

  between SATA and SCSI, and in general for motivation to hack on

  libata.

  </para>

  <para>

  libata's device detection

  method, ata_pio_devchk, and in general all the early probing was

  based on extensive study of Hale Landis's probe/reset code in his

  ATADRVR driver (www.ata-atapi.com).

  </para>

  </chapter>

</book>

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"

	"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>

<book id="scsidrivers">

 <bookinfo>

  <title>SCSI Subsystem Interfaces</title>

  <authorgroup>

   <author>

    <firstname>Douglas</firstname>

    <surname>Gilbert</surname>

    <affiliation>

     <address>

      <email>dgilbert@interlog.com</email>

     </address>

    </affiliation>

   </author>

  </authorgroup>

  <pubdate>2003-08-11</pubdate>

  <copyright>

   <year>2002</year>

   <year>2003</year>

   <holder>Douglas Gilbert</holder>

  </copyright>

  <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="intro">

      <title>Introduction</title>

  <para>

This document outlines the interface between the Linux scsi mid level

and lower level drivers. Lower level drivers are variously called HBA

(host bus adapter) drivers, host drivers (HD) or pseudo adapter drivers.

The latter alludes to the fact that a lower level driver may be a

bridge to another IO subsystem (and the "ide-scsi" driver is an example

of this). There can be many lower level drivers active in a running

system, but only one per hardware type. For example, the aic7xxx driver

controls adaptec controllers based on the 7xxx chip series. Most lower

level drivers can control one or more scsi hosts (a.k.a. scsi initiators).

  </para>

<para>

This document can been found in an ASCII text file in the linux kernel 

source: <filename>Documentation/scsi/scsi_mid_low_api.txt</filename> .

It currently hold a little more information than this document. The

<filename>drivers/scsi/hosts.h</filename> and <filename>

drivers/scsi/scsi.h</filename> headers contain descriptions of members

of important structures for the scsi subsystem.

</para>

  </chapter>

  <chapter id="driver-struct">

      <title>Driver structure</title>

  <para>

Traditionally a lower level driver for the scsi subsystem has been

at least two files in the drivers/scsi directory. For example, a

driver called "xyz" has a header file "xyz.h" and a source file

"xyz.c". [Actually there is no good reason why this couldn't all

be in one file.] Some drivers that have been ported to several operating

systems (e.g. aic7xxx which has separate  files for generic and

OS-specific code) have more than two files. Such drivers tend to have

their own directory under the drivers/scsi directory.

  </para>

  <para>

scsi_module.c is normally included at the end of a lower

level driver. For it to work a declaration like this is needed before

it is included:

<programlisting>

    static Scsi_Host_Template driver_template = DRIVER_TEMPLATE;

    /* DRIVER_TEMPLATE should contain pointers to supported interface

       functions. Scsi_Host_Template is defined hosts.h */

    #include "scsi_module.c"

</programlisting>

  </para>

  <para>

The scsi_module.c assumes the name "driver_template" is appropriately

defined. It contains 2 functions:

<orderedlist>

<listitem><para>

     init_this_scsi_driver() called during builtin and module driver

     initialization: invokes mid level's scsi_register_host()

</para></listitem>

<listitem><para>

     exit_this_scsi_driver() called during closedown: invokes

     mid level's scsi_unregister_host()

</para></listitem>

</orderedlist>

  </para>

<para>

When a new, lower level driver is being added to Linux, the following 

files (all found in the drivers/scsi directory) will need some attention: 

Makefile, Config.help and Config.in . It is probably best to look at what 

an existing lower level driver does in this regard.

</para>

  </chapter>

  <chapter id="intfunctions">

     <title>Interface Functions</title>

!EDocumentation/scsi/scsi_mid_low_api.txt

  </chapter>

  <chapter id="locks">

     <title>Locks</title>

<para>

Each Scsi_Host instance has a spin_lock called Scsi_Host::default_lock

which is initialized in scsi_register() [found in hosts.c]. Within the

same function the Scsi_Host::host_lock pointer is initialized to point

at default_lock with the scsi_assign_lock() function. Thereafter

lock and unlock operations performed by the mid level use the

Scsi_Host::host_lock pointer.

</para>

<para>

Lower level drivers can override the use of Scsi_Host::default_lock by

using scsi_assign_lock(). The earliest opportunity to do this would

be in the detect() function after it has invoked scsi_register(). It

could be replaced by a coarser grain lock (e.g. per driver) or a

lock of equal granularity (i.e. per host). Using finer grain locks

(e.g. per scsi device) may be possible by juggling locks in

queuecommand().

</para>

  </chapter>

  <chapter id="changes">

     <title>Changes since lk 2.4 series</title>

<para>

io_request_lock has been replaced by several finer grained locks. The lock

relevant to lower level drivers is Scsi_Host::host_lock and there is one

per scsi host.

</para>

<para>

The older error handling mechanism has been removed. This means the

lower level interface functions abort() and reset() have been removed.

</para>

<para>

In the 2.4 series the scsi subsystem configuration descriptions were

aggregated with the configuration descriptions from all other Linux

subsystems in the Documentation/Configure.help file. In the 2.5 series,

the scsi subsystem now has its own (much smaller) drivers/scsi/Config.help

file.

</para>

  </chapter>

  <chapter id="credits">

     <title>Credits</title>

<para>

The following people have contributed to this document:

<orderedlist>

<listitem><para>

Mike Anderson <email>andmike@us.ibm.com</email>

</para></listitem>

<listitem><para>

James Bottomley <email>James.Bottomley@steeleye.com</email>

</para></listitem>

<listitem><para>

Patrick Mansfield <email>patmans@us.ibm.com</email>

</para></listitem>

</orderedlist>

</para>

  </chapter>

</book>