[deliverable/linux.git] / Documentation / DocBook / libata.tmpl

<?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="libataDevGuide">
 <bookinfo>
  <title>libATA Developer's Guide</title>
  
  <authorgroup>
   <author>
    <firstname>Jeff</firstname>
    <surname>Garzik</surname>
   </author>
  </authorgroup>

  <copyright>
   <year>2003-2005</year>
   <holder>Jeff Garzik</holder>
  </copyright>

  <legalnotice>
   <para>
   The contents of this file are subject to the Open
   Software License version 1.1 that can be found at
   <ulink url="http://www.opensource.org/licenses/osl-1.1.txt">http://www.opensource.org/licenses/osl-1.1.txt</ulink> and is included herein
   by reference.
   </para>

   <para>
   Alternatively, the contents of this file may be used under the terms
   of the GNU General Public License version 2 (the "GPL") as distributed
   in the kernel source COPYING file, in which case the provisions of
   the GPL are applicable instead of the above.  If you wish to allow
   the use of your version of this file only under the terms of the
   GPL and not to allow others to use your version of this file under
   the OSL, indicate your decision by deleting the provisions above and
   replace them with the notice and other provisions required by the GPL.
   If you do not delete the provisions above, a recipient may use your
   version of this file under either the OSL or the GPL.
   </para>

  </legalnotice>
 </bookinfo>

<toc></toc>

  <chapter id="libataIntroduction">
     <title>Introduction</title>
  <para>
  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&lt;-&gt;ATA translation
  for ATA devices according to the T10 SAT specification.
  </para>
  <para>
  This Guide documents the libATA driver API, library functions, library
  internals, and a couple sample ATA low-level drivers.
  </para>
  </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>

  <chapter id="libataDriverApi">
     <title>libata Driver API</title>
     <sect1>
        <title>struct ata_port_operations</title>

	<programlisting>
void (*port_disable) (struct ata_port *);
	</programlisting>

	<para>
	Called from ata_bus_probe() and ata_bus_reset() error paths,
	as well as when unregistering from the SCSI module (rmmod, hot
	unplug).
	</para>

	<programlisting>
void (*dev_config) (struct ata_port *, struct ata_device *);
	</programlisting>

	<para>
	Called after IDENTIFY [PACKET] DEVICE is issued to each device
	found.  Typically used to apply device-specific fixups prior to
	issue of SET FEATURES - XFER MODE, and prior to operation.
	</para>

	<programlisting>
void (*set_piomode) (struct ata_port *, struct ata_device *);
void (*set_dmamode) (struct ata_port *, struct ata_device *);
void (*post_set_mode) (struct ata_port *ap);
	</programlisting>

	<para>
	Hooks called prior to the issue of SET FEATURES - XFER MODE
	command.  dev->pio_mode is guaranteed to be valid when
	->set_piomode() is called, and dev->dma_mode is guaranteed to be
	valid when ->set_dmamode() is called.  ->post_set_mode() is
	called unconditionally, after the SET FEATURES - XFER MODE
	command completes successfully.
	</para>

	<para>
	->set_piomode() is always called (if present), but
	->set_dma_mode() is only called if DMA is possible.
	</para>

	<programlisting>
void (*tf_load) (struct ata_port *ap, struct ata_taskfile *tf);
void (*tf_read) (struct ata_port *ap, struct ata_taskfile *tf);
	</programlisting>

	<para>
	->tf_load() is called to load the given taskfile into hardware
	registers / DMA buffers.  ->tf_read() is called to read the
	hardware registers / DMA buffers, to obtain the current set of
	taskfile register values.
	</para>

	<programlisting>
void (*exec_command)(struct ata_port *ap, struct ata_taskfile *tf);
	</programlisting>

	<para>
	causes an ATA command, previously loaded with
	->tf_load(), to be initiated in hardware.
	</para>

	<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>

	<programlisting>
u8   (*check_status)(struct ata_port *ap);
u8   (*check_altstatus)(struct ata_port *ap);
u8   (*check_err)(struct ata_port *ap);
	</programlisting>

	<para>
	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>

	<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.  This generally has no
meaning on FIS-based devices.
	</para>

	<programlisting>
void (*phy_reset) (struct ata_port *ap);
	</programlisting>

	<para>
	The very first step in the probe phase.  Actions vary depending
	on the bus type, typically.  After waking up the device and probing
	for device presence (PATA and SATA), typically a soft reset
	(SRST) will be performed.  Drivers typically use the helper
	functions ata_bus_reset() or sata_phy_reset() for this hook.
	</para>

	<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), 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>

	<programlisting>
void (*qc_prep) (struct ata_queued_cmd *qc);
int (*qc_issue) (struct ata_queued_cmd *qc);
	</programlisting>

	<para>
	Higher-level hooks, these two hooks can potentially supercede
	several of the above taskfile/DMA engine hooks.  ->qc_prep is
	called after the buffers have been DMA-mapped, and is typically
	used to populate the hardware's DMA scatter-gather table.
	Most drivers use the standard ata_qc_prep() helper function, but
	more advanced drivers roll their own.
	</para>
	<para>
	->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 implement their own ->qc_issue.
	</para>

	<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.  Most newer
hardware will implement its own error handling code here.  IDE BMDMA
drivers may use the helper function ata_eng_timeout().
	</para>

	<programlisting>
irqreturn_t (*irq_handler)(int, void *, struct pt_regs *);
void (*irq_clear) (struct ata_port *);
	</programlisting>

	<para>
	->irq_handler is the interrupt handling routine registered with
	the system, by libata.  ->irq_clear is called during probe just
	before the interrupt handler is registered, to be sure hardware
	is quiet.
	</para>

	<programlisting>
u32 (*scr_read) (struct ata_port *ap, unsigned int sc_reg);
void (*scr_write) (struct ata_port *ap, unsigned int sc_reg,
                   u32 val);
	</programlisting>

	<para>
	Read and write standard SATA phy registers.  Currently only used
	if ->phy_reset hook called the sata_phy_reset() helper function.
	</para>

	<programlisting>
int (*port_start) (struct ata_port *ap);
void (*port_stop) (struct ata_port *ap);
void (*host_stop) (struct ata_host_set *host_set);
	</programlisting>

	<para>
	->port_start() is called just after the data structures for each
	port are initialized.  Typically this is used to alloc per-port
	DMA buffers / tables / rings, enable DMA engines, and similar
	tasks.  
	</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>

     </sect1>
  </chapter>

  <chapter id="libataExt">
     <title>libata Library</title>
!Edrivers/scsi/libata-core.c
  </chapter>

  <chapter id="libataInt">
     <title>libata Core Internals</title>
!Idrivers/scsi/libata-core.c
  </chapter>

  <chapter id="libataScsiInt">
     <title>libata SCSI translation/emulation</title>
!Edrivers/scsi/libata-scsi.c
!Idrivers/scsi/libata-scsi.c
  </chapter>

  <chapter id="PiixInt">
     <title>ata_piix Internals</title>
!Idrivers/scsi/ata_piix.c
  </chapter>

  <chapter id="SILInt">
     <title>sata_sil Internals</title>
!Idrivers/scsi/sata_sil.c
  </chapter>

</book>
Commit	Line	Data
1da177e4 LT	1	<?xml version="1.0" encoding="UTF-8"?>
	2	<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
	3	"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>
	4
	5	<book id="libataDevGuide">
	6	<bookinfo>
	7	<title>libATA Developer's Guide</title>
	8
	9	<authorgroup>
	10	<author>
	11	<firstname>Jeff</firstname>
	12	<surname>Garzik</surname>
	13	</author>
	14	</authorgroup>
	15
	16	<copyright>
780a87f7	17	<year>2003-2005</year>
1da177e4 LT	18	<holder>Jeff Garzik</holder>
	19	</copyright>
	20
	21	<legalnotice>
	22	<para>
	23	The contents of this file are subject to the Open
	24	Software License version 1.1 that can be found at
	25	<ulink url="http://www.opensource.org/licenses/osl-1.1.txt">http://www.opensource.org/licenses/osl-1.1.txt</ulink> and is included herein
	26	by reference.
	27	</para>
	28
	29	<para>
	30	Alternatively, the contents of this file may be used under the terms
	31	of the GNU General Public License version 2 (the "GPL") as distributed
	32	in the kernel source COPYING file, in which case the provisions of
	33	the GPL are applicable instead of the above. If you wish to allow
	34	the use of your version of this file only under the terms of the
	35	GPL and not to allow others to use your version of this file under
	36	the OSL, indicate your decision by deleting the provisions above and
	37	replace them with the notice and other provisions required by the GPL.
	38	If you do not delete the provisions above, a recipient may use your
	39	version of this file under either the OSL or the GPL.
	40	</para>
	41
	42	</legalnotice>
	43	</bookinfo>
	44
	45	<toc></toc>
	46
07dd39b9 JG	47	<chapter id="libataIntroduction">
	48	<title>Introduction</title>
	49	<para>
	50	libATA is a library used inside the Linux kernel to support ATA host
	51	controllers and devices. libATA provides an ATA driver API, class
	52	transports for ATA and ATAPI devices, and SCSI<->ATA translation
	53	for ATA devices according to the T10 SAT specification.
	54	</para>
	55	<para>
	56	This Guide documents the libATA driver API, library functions, library
	57	internals, and a couple sample ATA low-level drivers.
	58	</para>
	59	</chapter>
	60
1da177e4 LT	61	<chapter id="libataThanks">
	62	<title>Thanks</title>
	63	<para>
	64	The bulk of the ATA knowledge comes thanks to long conversations with
07dd39b9 JG	65	Andre Hedrick (www.linux-ide.org), and long hours pondering the ATA
07dd39b9 JG	66	and SCSI specifications.
1da177e4 LT	67	</para>
	68	<para>
	69	Thanks to Alan Cox for pointing out similarities
	70	between SATA and SCSI, and in general for motivation to hack on
	71	libata.
	72	</para>
	73	<para>
	74	libata's device detection
	75	method, ata_pio_devchk, and in general all the early probing was
	76	based on extensive study of Hale Landis's probe/reset code in his
	77	ATADRVR driver (www.ata-atapi.com).
	78	</para>
	79	</chapter>
	80
	81	<chapter id="libataDriverApi">
	82	<title>libata Driver API</title>
	83	<sect1>
	84	<title>struct ata_port_operations</title>
	85
	86	<programlisting>
	87	void (port_disable) (struct ata_port );
	88	</programlisting>
	89
	90	<para>
	91	Called from ata_bus_probe() and ata_bus_reset() error paths,
	92	as well as when unregistering from the SCSI module (rmmod, hot
	93	unplug).
	94	</para>
	95
	96	<programlisting>
	97	void (dev_config) (struct ata_port , struct ata_device *);
	98	</programlisting>
	99
	100	<para>
	101	Called after IDENTIFY [PACKET] DEVICE is issued to each device
	102	found. Typically used to apply device-specific fixups prior to
	103	issue of SET FEATURES - XFER MODE, and prior to operation.
	104	</para>
	105
	106	<programlisting>
	107	void (set_piomode) (struct ata_port , struct ata_device *);
	108	void (set_dmamode) (struct ata_port , struct ata_device *);
	109	void (post_set_mode) (struct ata_port ap);
	110	</programlisting>
	111
	112	<para>
	113	Hooks called prior to the issue of SET FEATURES - XFER MODE
	114	command. dev->pio_mode is guaranteed to be valid when
	115	->set_piomode() is called, and dev->dma_mode is guaranteed to be
	116	valid when ->set_dmamode() is called. ->post_set_mode() is
	117	called unconditionally, after the SET FEATURES - XFER MODE
	118	command completes successfully.
	119	</para>
	120
	121	<para>
	122	->set_piomode() is always called (if present), but
	123	->set_dma_mode() is only called if DMA is possible.
	124	</para>
	125
	126	<programlisting>
	127	void (tf_load) (struct ata_port ap, struct ata_taskfile *tf);
	128	void (tf_read) (struct ata_port ap, struct ata_taskfile *tf);
	129	</programlisting>
	130
131	<para>
132	->tf_load() is called to load the given taskfile into hardware
133	registers / DMA buffers. ->tf_read() is called to read the
134	hardware registers / DMA buffers, to obtain the current set of
135	taskfile register values.
136	</para>
137
138	<programlisting>
139	void (exec_command)(struct ata_port ap, struct ata_taskfile *tf);
140	</programlisting>
141
142	<para>
143	causes an ATA command, previously loaded with
144	->tf_load(), to be initiated in hardware.
145	</para>
146
780a87f7 JG	147	<programlisting>
	148	int (check_atapi_dma) (struct ata_queued_cmd qc);
	149	</programlisting>
	150
	151	<para>
	152	Allow low-level driver to filter ATA PACKET commands, returning a status
	153	indicating whether or not it is OK to use DMA for the supplied PACKET
	154	command.
	155	</para>
	156
1da177e4 LT	157	<programlisting>
1da177e4 LT	158	u8 (check_status)(struct ata_port ap);
780a87f7 JG	159	u8 (check_altstatus)(struct ata_port ap);
780a87f7 JG	160	u8 (check_err)(struct ata_port ap);
1da177e4 LT	161	</programlisting>
	162
	163	<para>
780a87f7 JG	164	Reads the Status/AltStatus/Error ATA shadow register from
	165	hardware. On some hardware, reading the Status register has
	166	the side effect of clearing the interrupt condition.
1da177e4 LT	167	</para>
	168
	169	<programlisting>
	170	void (dev_select)(struct ata_port ap, unsigned int device);
	171	</programlisting>
	172
	173	<para>
	174	Issues the low-level hardware command(s) that causes one of N
	175	hardware devices to be considered 'selected' (active and
780a87f7 JG	176	available for use) on the ATA bus. This generally has no
780a87f7 JG	177	meaning on FIS-based devices.
1da177e4 LT	178	</para>
	179
	180	<programlisting>
	181	void (phy_reset) (struct ata_port ap);
	182	</programlisting>
	183
	184	<para>
	185	The very first step in the probe phase. Actions vary depending
	186	on the bus type, typically. After waking up the device and probing
	187	for device presence (PATA and SATA), typically a soft reset
	188	(SRST) will be performed. Drivers typically use the helper
	189	functions ata_bus_reset() or sata_phy_reset() for this hook.
	190	</para>
	191
	192	<programlisting>
	193	void (bmdma_setup) (struct ata_queued_cmd qc);
	194	void (bmdma_start) (struct ata_queued_cmd qc);
780a87f7 JG	195	void (bmdma_stop) (struct ata_port ap);
780a87f7 JG	196	u8 (bmdma_status) (struct ata_port ap);
1da177e4 LT	197	</programlisting>
	198
	199	<para>
780a87f7 JG	200	When setting up an IDE BMDMA transaction, these hooks arm
	201	(->bmdma_setup), fire (->bmdma_start), and halt (->bmdma_stop)
	202	the hardware's DMA engine. ->bmdma_status is used to read the standard
	203	PCI IDE DMA Status register.
	204	</para>
	205
	206	<para>
	207	These hooks are typically either no-ops, or simply not implemented, in
	208	FIS-based drivers.
1da177e4 LT	209	</para>
	210
	211	<programlisting>
	212	void (qc_prep) (struct ata_queued_cmd qc);
	213	int (qc_issue) (struct ata_queued_cmd qc);
	214	</programlisting>
	215
	216	<para>
	217	Higher-level hooks, these two hooks can potentially supercede
	218	several of the above taskfile/DMA engine hooks. ->qc_prep is
	219	called after the buffers have been DMA-mapped, and is typically
	220	used to populate the hardware's DMA scatter-gather table.
	221	Most drivers use the standard ata_qc_prep() helper function, but
	222	more advanced drivers roll their own.
	223	</para>
	224	<para>
	225	->qc_issue is used to make a command active, once the hardware
	226	and S/G tables have been prepared. IDE BMDMA drivers use the
	227	helper function ata_qc_issue_prot() for taskfile protocol-based
780a87f7	228	dispatch. More advanced drivers implement their own ->qc_issue.
1da177e4 LT	229	</para>
	230
	231	<programlisting>
	232	void (eng_timeout) (struct ata_port ap);
	233	</programlisting>
	234
	235	<para>
780a87f7 JG	236	This is a high level error handling function, called from the
	237	error handling thread, when a command times out. Most newer
	238	hardware will implement its own error handling code here. IDE BMDMA
	239	drivers may use the helper function ata_eng_timeout().
1da177e4 LT	240	</para>
	241
	242	<programlisting>
	243	irqreturn_t (irq_handler)(int, void , struct pt_regs *);
	244	void (irq_clear) (struct ata_port );
	245	</programlisting>
	246
	247	<para>
	248	->irq_handler is the interrupt handling routine registered with
	249	the system, by libata. ->irq_clear is called during probe just
	250	before the interrupt handler is registered, to be sure hardware
	251	is quiet.
	252	</para>
	253
	254	<programlisting>
	255	u32 (scr_read) (struct ata_port ap, unsigned int sc_reg);
	256	void (scr_write) (struct ata_port ap, unsigned int sc_reg,
	257	u32 val);
	258	</programlisting>
	259
	260	<para>
	261	Read and write standard SATA phy registers. Currently only used
	262	if ->phy_reset hook called the sata_phy_reset() helper function.
	263	</para>
	264
	265	<programlisting>
	266	int (port_start) (struct ata_port ap);
	267	void (port_stop) (struct ata_port ap);
	268	void (host_stop) (struct ata_host_set host_set);
	269	</programlisting>
	270
	271	<para>
	272	->port_start() is called just after the data structures for each
	273	port are initialized. Typically this is used to alloc per-port
	274	DMA buffers / tables / rings, enable DMA engines, and similar
	275	tasks.
	276	</para>
	277	<para>
1da177e4 LT	278	->port_stop() is called after ->host_stop(). It's sole function
	279	is to release DMA/memory resources, now that they are no longer
	280	actively being used.
	281	</para>
780a87f7 JG	282	<para>
	283	->host_stop() is called after all ->port_stop() calls
	284	have completed. The hook must finalize hardware shutdown, release DMA
	285	and other resources, etc.
	286	</para>
1da177e4 LT	287
	288	</sect1>
	289	</chapter>
	290
	291	<chapter id="libataExt">
	292	<title>libata Library</title>
	293	!Edrivers/scsi/libata-core.c
	294	</chapter>
	295
	296	<chapter id="libataInt">
	297	<title>libata Core Internals</title>
	298	!Idrivers/scsi/libata-core.c
	299	</chapter>
	300
	301	<chapter id="libataScsiInt">
	302	<title>libata SCSI translation/emulation</title>
	303	!Edrivers/scsi/libata-scsi.c
	304	!Idrivers/scsi/libata-scsi.c
	305	</chapter>
	306
	307	<chapter id="PiixInt">
	308	<title>ata_piix Internals</title>
	309	!Idrivers/scsi/ata_piix.c
	310	</chapter>
	311
	312	<chapter id="SILInt">
	313	<title>sata_sil Internals</title>
	314	!Idrivers/scsi/sata_sil.c
	315	</chapter>
	316
	317	</book>