[PATCH] Minor libata documentation patch

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

diff --git a/Documentation/DocBook/libata.tmpl b/Documentation/DocBook/libata.tmpl
index 6df1dfd..375ae76 100644 (file)
--- 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>