Merge of 'docs' branch from

  </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>

	return ata_pci_init_one(pdev, port_info, n_ports);

}

/**

 *	piix_init -

 *

 *	LOCKING:

 *

 *	RETURNS:

 *

 */

static int __init piix_init(void)

{

	int rc;

	return 0;

}

/**

 *	piix_exit -

 *

 *	LOCKING:

 *

 */

static void __exit piix_exit(void)

{

	pci_unregister_driver(&piix_pci_driver);