libata: more doc updates
Document recently-added ata_port_operations hooks.
Fill several doc stubs in libata-core.c.
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 @@
</para>
<programlisting>
-u8 (*check_status)(struct ata_port *ap);
-void (*dev_select)(struct ata_port *ap, unsigned int device);
+int (*check_atapi_dma) (struct ata_queued_cmd *qc);
</programlisting>
<para>
- Reads the Status ATA shadow register from hardware. On some
- hardware, this has the side effect of clearing the interrupt
- condition.
+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);
+u8 (*check_altstatus)(struct ata_port *ap);
+u8 (*check_err)(struct ata_port *ap);
+ </programlisting>
+
+ <para>
+ 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 @@
<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 @@
<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 @@
->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 @@
</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 @@
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>
diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
index 63d3f70..4d707d0 100644
--- a/drivers/scsi/libata-core.c
+++ b/drivers/scsi/libata-core.c
@@ -1241,10 +1241,14 @@
}
/**
- * __sata_phy_reset -
- * @ap:
+ * __sata_phy_reset - Wake/reset a low-level SATA PHY
+ * @ap: SATA port associated with target SATA PHY.
*
- * LOCKING:
+ * This function issues commands to standard SATA Sxxx
+ * PHY registers, to wake up the phy (and device), and
+ * clear any reset condition.
+ *
+ * LOCKING: None. Serialized during ata_bus_probe().
*
*/
void __sata_phy_reset(struct ata_port *ap)
@@ -1289,10 +1293,13 @@
}
/**
- * __sata_phy_reset -
- * @ap:
+ * sata_phy_reset - Reset SATA bus.
+ * @ap: SATA port associated with target SATA PHY.
*
- * LOCKING:
+ * This function resets the SATA bus, and then probes
+ * the bus for devices.
+ *
+ * LOCKING: None. Serialized during ata_bus_probe().
*
*/
void sata_phy_reset(struct ata_port *ap)
@@ -1304,10 +1311,16 @@
}
/**
- * ata_port_disable -
- * @ap:
+ * ata_port_disable - Disable port.
+ * @ap: Port to be disabled.
*
- * LOCKING:
+ * Modify @ap data structure such that the system
+ * thinks that the entire port is disabled, and should
+ * never attempt to probe or communicate with devices
+ * on this port.
+ *
+ * LOCKING: host_set lock, or some other form of
+ * serialization.
*/
void ata_port_disable(struct ata_port *ap)
@@ -1416,7 +1429,9 @@
* ata_set_mode - Program timings and issue SET FEATURES - XFER
* @ap: port on which timings will be programmed
*
- * LOCKING:
+ * Set ATA device disk transfer mode (PIO3, UDMA6, etc.).
+ *
+ * LOCKING: None. Serialized during ata_bus_probe().
*
*/
static void ata_set_mode(struct ata_port *ap)
@@ -1467,7 +1482,10 @@
* @tmout_pat: impatience timeout
* @tmout: overall timeout
*
- * LOCKING:
+ * Sleep until ATA Status register bit BSY clears,
+ * or a timeout occurs.
+ *
+ * LOCKING: None.
*
*/
@@ -1556,7 +1574,7 @@
* ata_bus_edd -
* @ap:
*
- * LOCKING:
+ * LOCKING: None. Serialized during ata_bus_probe().
*
*/
@@ -1909,7 +1927,10 @@
* @ap: Port associated with device @dev
* @dev: Device to which command will be sent
*
- * LOCKING:
+ * Issue SET FEATURES - XFER MODE command to device @dev
+ * on port @ap.
+ *
+ * LOCKING: None. Serialized during ata_bus_probe().
*/
static void ata_dev_set_xfermode(struct ata_port *ap, struct ata_device *dev)
@@ -1981,7 +2002,11 @@
* ata_fill_sg - Fill PCI IDE PRD table
* @qc: Metadata associated with taskfile to be transferred
*
+ * Fill PCI IDE PRD (scatter-gather) table with segments
+ * associated with the current disk command.
+ *
* LOCKING:
+ * spin_lock_irqsave(host_set lock)
*
*/
static void ata_fill_sg(struct ata_queued_cmd *qc)
@@ -2028,6 +2053,10 @@
* ata_check_atapi_dma - Check whether ATAPI DMA can be supported
* @qc: Metadata associated with taskfile to check
*
+ * 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.
+ *
* LOCKING:
* RETURNS: 0 when ATAPI DMA can be used
* nonzero otherwise
@@ -2046,6 +2075,8 @@
* ata_qc_prep - Prepare taskfile for submission
* @qc: Metadata associated with taskfile to be prepared
*
+ * Prepare ATA taskfile for submission.
+ *
* LOCKING:
* spin_lock_irqsave(host_set lock)
*/