1 files changed, 124 insertions, 32 deletions

diff --git a/Documentation/DocBook/libata.tmpl b/Documentation/DocBook/libata.tmpl
index cf2fce7707da..6df1dfd18b65 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>