Merge of 'docs' branch from

	rsync://rsync.kernel.org/pub/scm/linux/kernel/git/jgarzik/libata-dev

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>

drivers/scsi/ata_piix.c

@@ -665,15 +665,6 @@ static int piix_init_one (struct pci_dev *pdev, const struct pci_device_id *ent)
 	return ata_pci_init_one(pdev, port_info, n_ports);
 }
 
-/**
- *	piix_init -
- *
- *	LOCKING:
- *
- *	RETURNS:
- *
- */
-
 static int __init piix_init(void)
 {
 	int rc;
@@ -689,13 +680,6 @@ static int __init piix_init(void)
 	return 0;
 }
 
-/**
- *	piix_exit -
- *
- *	LOCKING:
- *
- */
-
 static void __exit piix_exit(void)
 {
 	pci_unregister_driver(&piix_pci_driver);

drivers/scsi/libata-scsi.c

@@ -947,7 +947,7 @@ unsigned int ata_scsiop_inq_83(struct ata_scsi_args *args, u8 *rbuf,
 }
 
 /**
- *	ata_scsiop_noop -
+ *	ata_scsiop_noop - Command handler that simply returns success.
  *	@args: device IDENTIFY data / SCSI command of interest.
  *	@rbuf: Response buffer, to which simulated SCSI cmd output is sent.
  *	@buflen: Response buffer length.

include/linux/libata.h

@@ -467,12 +467,34 @@ static inline u8 ata_chk_status(struct ata_port *ap)
 	return ap->ops->check_status(ap);
 }
 
+
+/**
+ *	ata_pause - Flush writes and pause 400 nanoseconds.
+ *	@ap: Port to wait for.
+ *
+ *	LOCKING:
+ *	Inherited from caller.
+ */
+
 static inline void ata_pause(struct ata_port *ap)
 {
 	ata_altstatus(ap);
 	ndelay(400);
 }
 
+
+/**
+ *	ata_busy_wait - Wait for a port status register
+ *	@ap: Port to wait for.
+ *
+ *	Waits up to max*10 microseconds for the selected bits in the port's
+ *	status register to be cleared.
+ *	Returns final value of status register.
+ *
+ *	LOCKING:
+ *	Inherited from caller.
+ */
+
 static inline u8 ata_busy_wait(struct ata_port *ap, unsigned int bits,
 			       unsigned int max)
 {
@@ -487,6 +509,18 @@ static inline u8 ata_busy_wait(struct ata_port *ap, unsigned int bits,
 	return status;
 }
 
+
+/**
+ *	ata_wait_idle - Wait for a port to be idle.
+ *	@ap: Port to wait for.
+ *
+ *	Waits up to 10ms for port's BUSY and DRQ signals to clear.
+ *	Returns final value of status register.
+ *
+ *	LOCKING:
+ *	Inherited from caller.
+ */
+
 static inline u8 ata_wait_idle(struct ata_port *ap)
 {
 	u8 status = ata_busy_wait(ap, ATA_BUSY | ATA_DRQ, 1000);
@@ -525,6 +559,18 @@ static inline void ata_tf_init(struct ata_port *ap, struct ata_taskfile *tf, uns
 		tf->device = ATA_DEVICE_OBS | ATA_DEV1;
 }
 
+
+/**
+ *	ata_irq_on - Enable interrupts on a port.
+ *	@ap: Port on which interrupts are enabled.
+ *
+ *	Enable interrupts on a legacy IDE device using MMIO or PIO,
+ *	wait for idle, clear any pending interrupts.
+ *
+ *	LOCKING:
+ *	Inherited from caller.
+ */
+
 static inline u8 ata_irq_on(struct ata_port *ap)
 {
 	struct ata_ioports *ioaddr = &ap->ioaddr;
@@ -544,6 +590,18 @@ static inline u8 ata_irq_on(struct ata_port *ap)
 	return tmp;
 }
 
+
+/**
+ *	ata_irq_ack - Acknowledge a device interrupt.
+ *	@ap: Port on which interrupts are enabled.
+ *
+ *	Wait up to 10 ms for legacy IDE device to become idle (BUSY
+ *	or BUSY+DRQ clear).  Obtain dma status and port status from
+ *	device.  Clear the interrupt.  Return port status.
+ *
+ *	LOCKING:
+ */
+
 static inline u8 ata_irq_ack(struct ata_port *ap, unsigned int chk_drq)
 {
 	unsigned int bits = chk_drq ? ATA_BUSY | ATA_DRQ : ATA_BUSY;