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authorJeff Garzik <jgarzik@pobox.com>2005-05-30 15:41:05 -0400
committerJeff Garzik <jgarzik@pobox.com>2005-05-30 15:41:05 -0400
commit780a87f71841932db8dbb0f1eb9daf3a973a6bd6 (patch)
tree443bad8a11c4502785265578e7a424ca3c67326a /Documentation
parent07dd39b9f62e0532c6922459c3a26d54a07bc231 (diff)
downloadop-kernel-dev-780a87f71841932db8dbb0f1eb9daf3a973a6bd6.zip
op-kernel-dev-780a87f71841932db8dbb0f1eb9daf3a973a6bd6.tar.gz
libata: more doc updates
Document recently-added ata_port_operations hooks. Fill several doc stubs in libata-core.c.
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/DocBook/libata.tmpl58
1 files changed, 39 insertions, 19 deletions
diff --git a/Documentation/DocBook/libata.tmpl b/Documentation/DocBook/libata.tmpl
index 773ae9f..41053ae 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>
@@ -145,14 +145,25 @@ void (*exec_command)(struct ata_port *ap, struct ata_taskfile *tf);
</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);
-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>
<programlisting>
@@ -162,7 +173,8 @@ 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>
<programlisting>
@@ -180,12 +192,20 @@ void (*phy_reset) (struct ata_port *ap);
<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>
<programlisting>
@@ -205,9 +225,7 @@ 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>
<programlisting>
@@ -215,8 +233,10 @@ 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>
<programlisting>
@@ -255,15 +275,15 @@ 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>
</sect1>
</chapter>
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