forked from luck/tmp_suning_uos_patched
375 lines
11 KiB
XML
375 lines
11 KiB
XML
<?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<->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="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>
|
|
|
|
<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>
|
|
|
|
</sect2>
|
|
|
|
<sect2><title>Post-IDENTIFY device configuration</title>
|
|
<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>
|
|
|
|
</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 *);
|
|
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>
|
|
|
|
</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);
|
|
</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>
|
|
|
|
</sect2>
|
|
|
|
<sect2><title>ATA command execute</title>
|
|
<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>
|
|
|
|
</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);
|
|
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>
|
|
|
|
</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. 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>
|
|
|
|
<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>
|
|
|
|
</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), 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);
|
|
</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>
|
|
|
|
</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. 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 *);
|
|
</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>
|
|
|
|
</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,
|
|
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>
|
|
|
|
</sect2>
|
|
|
|
<sect2><title>Init and shutdown</title>
|
|
<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>
|
|
|
|
</sect2>
|
|
|
|
</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>
|
|
|
|
<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>
|