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authorDmitry Torokhov <dtor_core@ameritech.net>2005-06-06 02:21:03 -0500
committerDmitry Torokhov <dtor_core@ameritech.net>2005-06-06 02:21:03 -0500
commit3c241f8337542655ee013a661b7f1770f561d3ef (patch)
tree79dd9a5dd12d305e1be7b926d414855377d2e192 /Documentation
parentdbf4ccd6043e58ed32fbf253fb3f0a9991e4c13a (diff)
parenteae936e21bd726f9d9555f2262d439fbcd61dccf (diff)
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Automatic merge of rsync://rsync.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/DocBook/libata.tmpl156
1 files changed, 124 insertions, 32 deletions
diff --git a/Documentation/DocBook/libata.tmpl b/Documentation/DocBook/libata.tmpl
index cf2fce7707d..6df1dfd18b6 100644
--- a/Documentation/DocBook/libata.tmpl
+++ b/Documentation/DocBook/libata.tmpl
@@ -14,7 +14,7 @@
</authorgroup>
<copyright>
- <year>2003</year>
+ <year>2003-2005</year>
<holder>Jeff Garzik</holder>
</copyright>
@@ -44,30 +44,38 @@
<toc></toc>
- <chapter id="libataThanks">
- <title>Thanks</title>
+ <chapter id="libataIntroduction">
+ <title>Introduction</title>
<para>
- The bulk of the ATA knowledge comes thanks to long conversations with
- Andre Hedrick (www.linux-ide.org).
+ 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>
- 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).
+ 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>
@@ -78,6 +86,9 @@ void (*port_disable) (struct ata_port *);
unplug).
</para>
+ </sect2>
+
+ <sect2><title>Post-IDENTIFY device configuration</title>
<programlisting>
void (*dev_config) (struct ata_port *, struct ata_device *);
</programlisting>
@@ -88,6 +99,9 @@ void (*dev_config) (struct ata_port *, struct ata_device *);
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 *);
@@ -108,6 +122,9 @@ void (*post_set_mode) (struct ata_port *ap);
->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);
@@ -120,6 +137,9 @@ 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>
@@ -129,17 +149,37 @@ void (*exec_command)(struct ata_port *ap, struct ata_taskfile *tf);
->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>
@@ -147,9 +187,13 @@ void (*dev_select)(struct ata_port *ap, unsigned int device);
<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>
@@ -162,17 +206,31 @@ void (*phy_reset) (struct ata_port *ap);
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.
+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);
@@ -190,20 +248,26 @@ 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.
+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 *);
@@ -216,6 +280,9 @@ 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,
@@ -227,6 +294,9 @@ 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);
@@ -240,15 +310,17 @@ void (*host_stop) (struct ata_host_set *host_set);
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>
@@ -279,4 +351,24 @@ void (*host_stop) (struct ata_host_set *host_set);
!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>