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Commit 8b2af8f0 authored by Edward Falk's avatar Edward Falk Committed by Jeff Garzik
Browse files

[PATCH] Minor libata documentation patch 

I fleshed out libata.tmpl a bit while I was taking notes.
parent c7b645f9

Documentation/DocBook/libata.tmpl

+93 −3
Original line number Original line Diff line number Diff line
@@ -84,6 +84,14 @@ void (*port_disable) (struct ata_port *); 
	Called from ata_bus_probe() and ata_bus_reset() error paths,

	Called from ata_bus_probe() and ata_bus_reset() error paths,

	as well as when unregistering from the SCSI module (rmmod, hot

	as well as when unregistering from the SCSI module (rmmod, hot

	unplug).

	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>

	</para>





	</sect2>

	</sect2>
@@ -98,6 +106,13 @@ void (*dev_config) (struct ata_port *, struct ata_device *); 
	found.  Typically used to apply device-specific fixups prior to

	found.  Typically used to apply device-specific fixups prior to

	issue of SET FEATURES - XFER MODE, and prior to operation.

	issue of SET FEATURES - XFER MODE, and prior to operation.

	</para>

	</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>

	</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

	registers / DMA buffers.  ->tf_read() is called to read the

	hardware registers / DMA buffers, to obtain the current set of

	hardware registers / DMA buffers, to obtain the current set of

	taskfile register values.

	taskfile register values.

	Most drivers for taskfile-based hardware (PIO or MMIO) use

	ata_tf_load() and ata_tf_read() for these hooks.

	</para>

	</para>





	</sect2>

	</sect2>
@@ -147,6 +164,8 @@ void (*exec_command)(struct ata_port *ap, struct ata_taskfile *tf); 
	<para>

	<para>

	causes an ATA command, previously loaded with

	causes an ATA command, previously loaded with

	->tf_load(), to be initiated in hardware.

	->tf_load(), to be initiated in hardware.

	Most drivers for taskfile-based hardware use ata_exec_command()

	for this hook.

	</para>

	</para>





	</sect2>

	</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

indicating whether or not it is OK to use DMA for the supplied PACKET

command.

command.

	</para>

	</para>

	<para>

	This hook may be specified as NULL, in which case libata will

	assume that atapi dma can be supported.

	</para>





	</sect2>

	</sect2>
@@ -175,6 +198,14 @@ u8 (*check_err)(struct ata_port *ap); 
	Reads the Status/AltStatus/Error ATA shadow register from

	Reads the Status/AltStatus/Error ATA shadow register from

	hardware.  On some hardware, reading the Status register has

	hardware.  On some hardware, reading the Status register has

	the side effect of clearing the interrupt condition.

	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>

	</para>





	</sect2>

	</sect2>
@@ -190,6 +221,12 @@ void (*dev_select)(struct ata_port *ap, unsigned int device); 
	available for use) on the ATA bus.  This generally has no

	available for use) on the ATA bus.  This generally has no

	meaning on FIS-based devices.

	meaning on FIS-based devices.

	</para>

	</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>

	</sect2>
@@ -204,6 +241,8 @@ void (*phy_reset) (struct ata_port *ap); 
	for device presence (PATA and SATA), typically a soft reset

	for device presence (PATA and SATA), typically a soft reset

	(SRST) will be performed.  Drivers typically use the helper

	(SRST) will be performed.  Drivers typically use the helper

	functions ata_bus_reset() or sata_phy_reset() for this hook.

	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>

	</para>





	</sect2>

	</sect2>
@@ -227,6 +266,25 @@ PCI IDE DMA Status register. 
These hooks are typically either no-ops, or simply not implemented, in

These hooks are typically either no-ops, or simply not implemented, in

FIS-based drivers.

FIS-based drivers.

	</para>

	</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>

	</sect2>
@@ -250,6 +308,10 @@ int (*qc_issue) (struct ata_queued_cmd *qc); 
	helper function ata_qc_issue_prot() for taskfile protocol-based

	helper function ata_qc_issue_prot() for taskfile protocol-based

	dispatch.  More advanced drivers implement their own ->qc_issue.

	dispatch.  More advanced drivers implement their own ->qc_issue.

	</para>

	</para>

	<para>

	ata_qc_issue_prot() calls ->tf_load(), ->bmdma_setup(), and

	->bmdma_start() as necessary to initiate a transfer.

	</para>





	</sect2>

	</sect2>
@@ -279,6 +341,21 @@ void (*irq_clear) (struct ata_port *); 
	before the interrupt handler is registered, to be sure hardware

	before the interrupt handler is registered, to be sure hardware

	is quiet.

	is quiet.

	</para>

	</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>

	</sect2>
@@ -292,6 +369,7 @@ void (*scr_write) (struct ata_port *ap, unsigned int sc_reg, 
	<para>

	<para>

	Read and write standard SATA phy registers.  Currently only used

	Read and write standard SATA phy registers.  Currently only used

	if ->phy_reset hook called the sata_phy_reset() helper function.

	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>

	</para>





	</sect2>

	</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_start() is called just after the data structures for each

	port are initialized.  Typically this is used to alloc per-port

	port are initialized.  Typically this is used to alloc per-port

	DMA buffers / tables / rings, enable DMA engines, and similar

	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>

	<para>

	<para>

	->port_stop() is called after ->host_stop().  It's sole function

	->port_stop() is called after ->host_stop().  It's sole function

	is to release DMA/memory resources, now that they are no longer

	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>

	<para>

	<para>

	->host_stop() is called after all ->port_stop() calls

	->host_stop() is called after all ->port_stop() calls

have completed.  The hook must finalize hardware shutdown, release DMA

have completed.  The hook must finalize hardware shutdown, release DMA

and other resources, etc.

and other resources, etc.

	This hook may be specified as NULL, in which case it is not called.

	</para>

	</para>





	</sect2>

	</sect2>