[PATCH] Minor libata documentation patch

I fleshed out libata.tmpl a bit while I was taking notes.

1 files changed, 93 insertions, 3 deletions

diff --git a/Documentation/DocBook/libata.tmpl b/Documentation/DocBook/libata.tmpl
index 6df1dfd18b65..375ae760dc1e 100644
--- a/Documentation/DocBook/libata.tmpl
+++ b/Documentation/DocBook/libata.tmpl
@@ -84,6 +84,14 @@ void (*port_disable) (struct ata_port *);
         Called from ata_bus_probe() and ata_bus_reset() error paths,
         as well as when unregistering from the SCSI module (rmmod, hot
         unplug).
+        This function should do whatever needs to be done to take the
+        port out of use.  In most cases, ata_port_disable() can be used
+        as this hook.
+        </para>
+        <para>
+        Called from ata_bus_probe() on a failed probe.
+        Called from ata_bus_reset() on a failed bus reset.
+        Called from ata_scsi_release().
         </para>
 
         </sect2>
@@ -98,6 +106,13 @@ void (*dev_config) (struct ata_port *, struct ata_device *);
         found.  Typically used to apply device-specific fixups prior to
         issue of SET FEATURES - XFER MODE, and prior to operation.
         </para>
+        <para>
+        Called by ata_device_add() after ata_dev_identify() determines
+        a device is present.
+        </para>
+        <para>
+        This entry may be specified as NULL in ata_port_operations.
+        </para>
 
         </sect2>
 
@@ -135,6 +150,8 @@ void (*tf_read) (struct ata_port *ap, struct ata_taskfile *tf);
         registers / DMA buffers.  ->tf_read() is called to read the
         hardware registers / DMA buffers, to obtain the current set of
         taskfile register values.
+        Most drivers for taskfile-based hardware (PIO or MMIO) use
+        ata_tf_load() and ata_tf_read() for these hooks.
         </para>
 
         </sect2>
@@ -147,6 +164,8 @@ void (*exec_command)(struct ata_port *ap, struct ata_taskfile *tf);
         <para>
         causes an ATA command, previously loaded with
         ->tf_load(), to be initiated in hardware.
+        Most drivers for taskfile-based hardware use ata_exec_command()
+        for this hook.
         </para>
 
         </sect2>
@@ -161,6 +180,10 @@ 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>
+        <para>
+        This hook may be specified as NULL, in which case libata will
+        assume that atapi dma can be supported.
+        </para>
 
         </sect2>
 
@@ -175,6 +198,14 @@ u8   (*check_err)(struct ata_port *ap);
         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.
+        Most drivers for taskfile-based hardware use
+        ata_check_status() for this hook.
+        </para>
+        <para>
+        Note that because this is called from ata_device_add(), at
+        least a dummy function that clears device interrupts must be
+        provided for all drivers, even if the controller doesn't
+        actually have a taskfile status register.
         </para>
 
         </sect2>
@@ -188,7 +219,13 @@ void (*dev_select)(struct ata_port *ap, unsigned int device);
         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.  This generally has no
-meaning on FIS-based devices.
+        meaning on FIS-based devices.
+        </para>
+        <para>
+        Most drivers for taskfile-based hardware use
+        ata_std_dev_select() for this hook.  Controllers which do not
+        support second drives on a port (such as SATA contollers) will
+        use ata_noop_dev_select().
         </para>
 
         </sect2>
@@ -204,6 +241,8 @@ void (*phy_reset) (struct ata_port *ap);
         for device presence (PATA and SATA), typically a soft reset
         (SRST) will be performed.  Drivers typically use the helper
         functions ata_bus_reset() or sata_phy_reset() for this hook.
+        Many SATA drivers use sata_phy_reset() or call it from within
+        their own phy_reset() functions.
         </para>
 
         </sect2>
@@ -227,6 +266,25 @@ PCI IDE DMA Status register.
 These hooks are typically either no-ops, or simply not implemented, in
 FIS-based drivers.
         </para>
+        <para>
+Most legacy IDE drivers use ata_bmdma_setup() for the bmdma_setup()
+hook.  ata_bmdma_setup() will write the pointer to the PRD table to
+the IDE PRD Table Address register, enable DMA in the DMA Command
+register, and call exec_command() to begin the transfer.
+        </para>
+        <para>
+Most legacy IDE drivers use ata_bmdma_start() for the bmdma_start()
+hook.  ata_bmdma_start() will write the ATA_DMA_START flag to the DMA
+Command register.
+        </para>
+        <para>
+Many legacy IDE drivers use ata_bmdma_stop() for the bmdma_stop()
+hook.  ata_bmdma_stop() clears the ATA_DMA_START flag in the DMA
+command register.
+        </para>
+        <para>
+Many legacy IDE drivers use ata_bmdma_status() as the bmdma_status() hook.
+        </para>
 
         </sect2>
 
@@ -250,6 +308,10 @@ int (*qc_issue) (struct ata_queued_cmd *qc);
         helper function ata_qc_issue_prot() for taskfile protocol-based
         dispatch.  More advanced drivers implement their own ->qc_issue.
         </para>
+        <para>
+        ata_qc_issue_prot() calls ->tf_load(), ->bmdma_setup(), and
+        ->bmdma_start() as necessary to initiate a transfer.
+        </para>
 
         </sect2>
 
@@ -279,6 +341,21 @@ void (*irq_clear) (struct ata_port *);
         before the interrupt handler is registered, to be sure hardware
         is quiet.
         </para>
+        <para>
+        The second argument, dev_instance, should be cast to a pointer
+        to struct ata_host_set.
+        </para>
+        <para>
+        Most legacy IDE drivers use ata_interrupt() for the
+        irq_handler hook, which scans all ports in the host_set,
+        determines which queued command was active (if any), and calls
+        ata_host_intr(ap,qc).
+        </para>
+        <para>
+        Most legacy IDE drivers use ata_bmdma_irq_clear() for the
+        irq_clear() hook, which simply clears the interrupt and error
+        flags in the DMA status register.
+        </para>
 
         </sect2>
 
@@ -292,6 +369,7 @@ void (*scr_write) (struct ata_port *ap, unsigned int sc_reg,
         <para>
         Read and write standard SATA phy registers.  Currently only used
         if ->phy_reset hook called the sata_phy_reset() helper function.
+        sc_reg is one of SCR_STATUS, SCR_CONTROL, SCR_ERROR, or SCR_ACTIVE.
         </para>
 
         </sect2>
@@ -307,17 +385,29 @@ void (*host_stop) (struct ata_host_set *host_set);
         ->port_start() is called just after the data structures for each
         port are initialized.  Typically this is used to alloc per-port
         DMA buffers / tables / rings, enable DMA engines, and similar
-        tasks.  
+        tasks.  Some drivers also use this entry point as a chance to
+        allocate driver-private memory for ap->private_data.
+        </para>
+        <para>
+        Many drivers use ata_port_start() as this hook or call
+        it from their own port_start() hooks.  ata_port_start()
+        allocates space for a legacy IDE PRD table and returns.
         </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.
+        actively being used.  Many drivers also free driver-private
+        data from port at this time.
+        </para>
+        <para>
+        Many drivers use ata_port_stop() as this hook, which frees the
+        PRD table.
         </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.
+        This hook may be specified as NULL, in which case it is not called.
         </para>
 
         </sect2>