libata: more doc updates

[linux-2.6] / Documentation / DocBook / libata.tmpl

diff --git a/Documentation/DocBook/libata.tmpl b/Documentation/DocBook/libata.tmpl
index cf2fce7707da202e7f408f40929dde7255cf742e..41053aed41f474544e6521876abaf3c76dbff93f 100644 (file)
--- 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>
 
@@ -44,11 +44,26 @@
 
 <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).
+  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 
@@ -129,15 +144,26 @@ void (*exec_command)(struct ata_port *ap, struct ata_taskfile *tf);
        ->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);
-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>
@@ -147,7 +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>
@@ -165,12 +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>
@@ -190,9 +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>
@@ -200,8 +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>
@@ -240,15 +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>