[PATCH v2 31/53] docs-rst: convert z8530book DocBook to ReST

From: Mauro Carvalho Chehab <mchehab@s-opensource.com>
To: Linux Doc Mailing List <linux-doc@vger.kernel.org>
Cc: Mauro Carvalho Chehab <mchehab@s-opensource.com>,
	Mauro Carvalho Chehab <mchehab@infradead.org>,
	linux-kernel@vger.kernel.org, Jonathan Corbet <corbet@lwn.net>,
	David Woodhouse <dwmw2@infradead.org>,
	Brian Norris <computersforpeace@gmail.com>,
	Boris Brezillon <boris.brezillon@free-electrons.com>,
	Marek Vasut <marek.vasut@gmail.com>,
	Richard Weinberger <richard@nod.at>,
	Cyrille Pitchen <cyrille.pitchen@atmel.com>,
	linux-mtd@lists.infradead.org,
	Jani Nikula <jani.nikula@intel.com>,
	"Herton R. Krzesinski" <herton@redhat.com>,
	Markus Heiser <markus.heiser@darmarit.de>
Subject: [PATCH v2 31/53] docs-rst: convert z8530book DocBook to ReST
Date: Tue, 16 May 2017 09:16:23 -0300	[thread overview]
Message-ID: <c7e2154475177a247cd94bf6a8646627a6ae1055.1494935649.git.mchehab@s-opensource.com> (raw)
In-Reply-To: <cover.1494935649.git.mchehab@s-opensource.com>
In-Reply-To: <cover.1494935649.git.mchehab@s-opensource.com>

Use pandoc to convert documentation to ReST by calling
Documentation/sphinx/tmplcvt script.

Some manual adjustments were required due to some
conversion error on some literals.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
---
 Documentation/DocBook/Makefile         |   2 +-
 Documentation/DocBook/z8530book.tmpl   | 371 ---------------------------------
 Documentation/networking/index.rst     |   1 +
 Documentation/networking/z8530book.rst | 257 +++++++++++++++++++++++
 4 files changed, 259 insertions(+), 372 deletions(-)
 delete mode 100644 Documentation/DocBook/z8530book.tmpl
 create mode 100644 Documentation/networking/z8530book.rst

diff --git a/Documentation/DocBook/Makefile b/Documentation/DocBook/Makefile
index 8a90891c3712..00a61f4ffcff 100644
--- a/Documentation/DocBook/Makefile
+++ b/Documentation/DocBook/Makefile
@@ -6,7 +6,7 @@
 # To add a new book the only step required is to add the book to the
 # list of DOCBOOKS.
 
-DOCBOOKS := z8530book.xml  \
+DOCBOOKS := \
 	    lsm.xml \
 	    mtdnand.xml librs.xml rapidio.xml \
 	    scsi.xml \
diff --git a/Documentation/DocBook/z8530book.tmpl b/Documentation/DocBook/z8530book.tmpl
deleted file mode 100644
index 6f3883be877e..000000000000
--- a/Documentation/DocBook/z8530book.tmpl
+++ /dev/null
@@ -1,371 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
-	"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []>
-
-<book id="Z85230Guide">
- <bookinfo>
-  <title>Z8530 Programming Guide</title>
-  
-  <authorgroup>
-   <author>
-    <firstname>Alan</firstname>
-    <surname>Cox</surname>
-    <affiliation>
-     <address>
-      <email>alan@lxorguk.ukuu.org.uk</email>
-     </address>
-    </affiliation>
-   </author>
-  </authorgroup>
-
-  <copyright>
-   <year>2000</year>
-   <holder>Alan Cox</holder>
-  </copyright>
-
-  <legalnotice>
-   <para>
-     This documentation is free software; you can redistribute
-     it and/or modify it under the terms of the GNU General Public
-     License as published by the Free Software Foundation; either
-     version 2 of the License, or (at your option) any later
-     version.
-   </para>
-      
-   <para>
-     This program is distributed in the hope that it will be
-     useful, but WITHOUT ANY WARRANTY; without even the implied
-     warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
-     See the GNU General Public License for more details.
-   </para>
-      
-   <para>
-     You should have received a copy of the GNU General Public
-     License along with this program; if not, write to the Free
-     Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
-     MA 02111-1307 USA
-   </para>
-      
-   <para>
-     For more details see the file COPYING in the source
-     distribution of Linux.
-   </para>
-  </legalnotice>
- </bookinfo>
-
-<toc></toc>
-
-  <chapter id="intro">
-      <title>Introduction</title>
-  <para>
-	The Z85x30 family synchronous/asynchronous controller chips are
-	used on a large number of cheap network interface cards. The
-	kernel provides a core interface layer that is designed to make
-	it easy to provide WAN services using this chip.
-  </para>
-  <para>
-	The current driver only support synchronous operation. Merging the
-	asynchronous driver support into this code to allow any Z85x30
-	device to be used as both a tty interface and as a synchronous 
-	controller is a project for Linux post the 2.4 release
-  </para>
-  </chapter>
-  
-  <chapter id="Driver_Modes">
- 	<title>Driver Modes</title>
-  <para>
-	The Z85230 driver layer can drive Z8530, Z85C30 and Z85230 devices
-	in three different modes. Each mode can be applied to an individual
-	channel on the chip (each chip has two channels).
-  </para>
-  <para>
-	The PIO synchronous mode supports the most common Z8530 wiring. Here
-	the chip is interface to the I/O and interrupt facilities of the
-	host machine but not to the DMA subsystem. When running PIO the
-	Z8530 has extremely tight timing requirements. Doing high speeds,
-	even with a Z85230 will be tricky. Typically you should expect to
-	achieve at best 9600 baud with a Z8C530 and 64Kbits with a Z85230.
-  </para>
-  <para>
-	The DMA mode supports the chip when it is configured to use dual DMA
-	channels on an ISA bus. The better cards tend to support this mode
-	of operation for a single channel. With DMA running the Z85230 tops
-	out when it starts to hit ISA DMA constraints at about 512Kbits. It
-	is worth noting here that many PC machines hang or crash when the
-	chip is driven fast enough to hold the ISA bus solid.
-  </para>
-  <para>
-	Transmit DMA mode uses a single DMA channel. The DMA channel is used
-	for transmission as the transmit FIFO is smaller than the receive
-	FIFO. it gives better performance than pure PIO mode but is nowhere
-	near as ideal as pure DMA mode. 
-  </para>
-  </chapter>
-
-  <chapter id="Using_the_Z85230_driver">
- 	<title>Using the Z85230 driver</title>
-  <para>
-	The Z85230 driver provides the back end interface to your board. To
-	configure a Z8530 interface you need to detect the board and to 
-	identify its ports and interrupt resources. It is also your problem
-	to verify the resources are available.
-  </para>
-  <para>
-	Having identified the chip you need to fill in a struct z8530_dev,
-	which describes each chip. This object must exist until you finally
-	shutdown the board. Firstly zero the active field. This ensures 
-	nothing goes off without you intending it. The irq field should
-	be set to the interrupt number of the chip. (Each chip has a single
-	interrupt source rather than each channel). You are responsible
-	for allocating the interrupt line. The interrupt handler should be
-	set to <function>z8530_interrupt</function>. The device id should
-	be set to the z8530_dev structure pointer. Whether the interrupt can
-	be shared or not is board dependent, and up to you to initialise.
-  </para>
-  <para>
-	The structure holds two channel structures. 
-	Initialise chanA.ctrlio and chanA.dataio with the address of the
-	control and data ports. You can or this with Z8530_PORT_SLEEP to
-	indicate your interface needs the 5uS delay for chip settling done
-	in software. The PORT_SLEEP option is architecture specific. Other
-	flags may become available on future platforms, eg for MMIO.
-	Initialise the chanA.irqs to &amp;z8530_nop to start the chip up
-	as disabled and discarding interrupt events. This ensures that
-	stray interrupts will be mopped up and not hang the bus. Set
-	chanA.dev to point to the device structure itself. The
-	private and name field you may use as you wish. The private field
-	is unused by the Z85230 layer. The name is used for error reporting
-	and it may thus make sense to make it match the network name.
-  </para>
-  <para>
-	Repeat the same operation with the B channel if your chip has
-	both channels wired to something useful. This isn't always the
-	case. If it is not wired then the I/O values do not matter, but
-	you must initialise chanB.dev.
-  </para>
-  <para>
-	If your board has DMA facilities then initialise the txdma and
-	rxdma fields for the relevant channels. You must also allocate the
-	ISA DMA channels and do any necessary board level initialisation
-	to configure them. The low level driver will do the Z8530 and
-	DMA controller programming but not board specific magic.
-  </para>
-  <para>
-	Having initialised the device you can then call
-	<function>z8530_init</function>. This will probe the chip and 
-	reset it into a known state. An identification sequence is then
-	run to identify the chip type. If the checks fail to pass the
-	function returns a non zero error code. Typically this indicates
-	that the port given is not valid. After this call the
-	type field of the z8530_dev structure is initialised to either
-	Z8530, Z85C30 or Z85230 according to the chip found.
-  </para>
-  <para>
-	Once you have called z8530_init you can also make use of the utility
-	function <function>z8530_describe</function>. This provides a 
-	consistent reporting format for the Z8530 devices, and allows all
-	the drivers to provide consistent reporting.
-  </para>
-  </chapter>
-
-  <chapter id="Attaching_Network_Interfaces">
- 	<title>Attaching Network Interfaces</title>
-  <para>
-	If you wish to use the network interface facilities of the driver,
-	then you need to attach a network device to each channel that is
-	present and in use. In addition to use the generic HDLC
-	you need to follow some additional plumbing rules. They may seem 
-	complex but a look at the example hostess_sv11 driver should
-	reassure you.
-  </para>
-  <para>
-	The network device used for each channel should be pointed to by
-	the netdevice field of each channel. The hdlc-&gt; priv field of the
-	network device points to your private data - you will need to be
-	able to find your private data from this.
-  </para>
-  <para>
-	The way most drivers approach this particular problem is to
-	create a structure holding the Z8530 device definition and
-	put that into the private field of the network device. The
-	network device fields of the channels then point back to the
-	network devices.
-  </para>
-  <para>
-	If you wish to use the generic HDLC then you need to register
-	the HDLC device.
-  </para>
-  <para>
-	Before you register your network device you will also need to
-	provide suitable handlers for most of the network device callbacks. 
-	See the network device documentation for more details on this.
-  </para>
-  </chapter>
-
-  <chapter id="Configuring_And_Activating_The_Port">
- 	<title>Configuring And Activating The Port</title>
-  <para>
-	The Z85230 driver provides helper functions and tables to load the
-	port registers on the Z8530 chips. When programming the register
-	settings for a channel be aware that the documentation recommends
-	initialisation orders. Strange things happen when these are not
-	followed. 
-  </para>
-  <para>
-	<function>z8530_channel_load</function> takes an array of
-	pairs of initialisation values in an array of u8 type. The first
-	value is the Z8530 register number. Add 16 to indicate the alternate
-	register bank on the later chips. The array is terminated by a 255.
-  </para>
-  <para>
-	The driver provides a pair of public tables. The
-	z8530_hdlc_kilostream table is for the UK 'Kilostream' service and
-	also happens to cover most other end host configurations. The
-	z8530_hdlc_kilostream_85230 table is the same configuration using
-	the enhancements of the 85230 chip. The configuration loaded is
-	standard NRZ encoded synchronous data with HDLC bitstuffing. All
-	of the timing is taken from the other end of the link.
-  </para>
-  <para>
-	When writing your own tables be aware that the driver internally
-	tracks register values. It may need to reload values. You should
-	therefore be sure to set registers 1-7, 9-11, 14 and 15 in all
-	configurations. Where the register settings depend on DMA selection
-	the driver will update the bits itself when you open or close.
-	Loading a new table with the interface open is not recommended.
-  </para>
-  <para>
-	There are three standard configurations supported by the core
-	code. In PIO mode the interface is programmed up to use
-	interrupt driven PIO. This places high demands on the host processor
-	to avoid latency. The driver is written to take account of latency
-	issues but it cannot avoid latencies caused by other drivers,
-	notably IDE in PIO mode. Because the drivers allocate buffers you
-	must also prevent MTU changes while the port is open.
-  </para>
-  <para>
-	Once the port is open it will call the rx_function of each channel
-	whenever a completed packet arrived. This is invoked from
-	interrupt context and passes you the channel and a network	
-	buffer (struct sk_buff) holding the data. The data includes
-	the CRC bytes so most users will want to trim the last two
-	bytes before processing the data. This function is very timing
-	critical. When you wish to simply discard data the support
-	code provides the function <function>z8530_null_rx</function>
-	to discard the data.
-  </para>
-  <para>
-	To active PIO mode sending and receiving the <function>
-	z8530_sync_open</function> is called. This expects to be passed
-	the network device and the channel. Typically this is called from
-	your network device open callback. On a failure a non zero error
-	status is returned. The <function>z8530_sync_close</function> 
-	function shuts down a PIO channel. This must be done before the 
-	channel is opened again	and before the driver shuts down 
-	and unloads.
-  </para>
-  <para>
-	The ideal mode of operation is dual channel DMA mode. Here the
-	kernel driver will configure the board for DMA in both directions.
-	The driver also handles ISA DMA issues such as controller
-	programming and the memory range limit for you. This mode is
-	activated by calling the <function>z8530_sync_dma_open</function>
-	function. On failure a non zero error value is returned.
-	Once this mode is activated it can be shut down by calling the
-	<function>z8530_sync_dma_close</function>. You must call the close
-	function matching the open mode you used.
-  </para>
-  <para>
-	The final supported mode uses a single DMA channel to drive the
-	transmit side. As the Z85C30 has a larger FIFO on the receive
-	channel	this tends to increase the maximum speed a little. 
-	This is activated by calling the <function>z8530_sync_txdma_open
-	</function>. This returns a non zero error code on failure. The
-	<function>z8530_sync_txdma_close</function> function closes down
-	the Z8530 interface from this mode.
-  </para>
-  </chapter>
-
-  <chapter id="Network_Layer_Functions">
- 	<title>Network Layer Functions</title>
-  <para>
-	The Z8530 layer provides functions to queue packets for
-	transmission. The driver internally buffers the frame currently
-	being transmitted and one further frame (in order to keep back
-	to back transmission running). Any further buffering is up to
-	the caller.
-  </para>
-  <para>
-	The function <function>z8530_queue_xmit</function> takes a network
-	buffer in sk_buff format and queues it for transmission. The
-	caller must provide the entire packet with the exception of the
-	bitstuffing and CRC. This is normally done by the caller via
-	the generic HDLC interface layer. It returns 0 if the buffer has been
-	queued and non zero values for queue full. If the function accepts
-	the buffer it becomes property of the Z8530 layer and the caller
-	should not free it.
-  </para>
-  <para>
-	The function <function>z8530_get_stats</function> returns a pointer
-	to an internally maintained per interface statistics block. This
-	provides most of the interface code needed to implement the network
-	layer get_stats callback.
-  </para>
-  </chapter>
-
-  <chapter id="Porting_The_Z8530_Driver">
-     <title>Porting The Z8530 Driver</title>
-  <para>
-	The Z8530 driver is written to be portable. In DMA mode it makes
-	assumptions about the use of ISA DMA. These are probably warranted
-	in most cases as the Z85230 in particular was designed to glue to PC
-	type machines. The PIO mode makes no real assumptions.
-  </para>
-  <para>
-	Should you need to retarget the Z8530 driver to another architecture
-	the only code that should need changing are the port I/O functions.
-	At the moment these assume PC I/O port accesses. This may not be
-	appropriate for all platforms. Replacing 
-	<function>z8530_read_port</function> and <function>z8530_write_port
-	</function> is intended to be all that is required to port this
-	driver layer.
-  </para>
-  </chapter>
-
-  <chapter id="bugs">
-     <title>Known Bugs And Assumptions</title>
-  <para>
-  <variablelist>
-    <varlistentry><term>Interrupt Locking</term>
-    <listitem>
-    <para>
-	The locking in the driver is done via the global cli/sti lock. This
-	makes for relatively poor SMP performance. Switching this to use a
-	per device spin lock would probably materially improve performance.
-    </para>
-    </listitem></varlistentry>
-
-    <varlistentry><term>Occasional Failures</term>
-    <listitem>
-    <para>
-	We have reports of occasional failures when run for very long
-	periods of time and the driver starts to receive junk frames. At
-	the moment the cause of this is not clear.
-    </para>
-    </listitem></varlistentry>
-  </variablelist>
-	
-  </para>
-  </chapter>
-
-  <chapter id="pubfunctions">
-     <title>Public Functions Provided</title>
-!Edrivers/net/wan/z85230.c
-  </chapter>
-
-  <chapter id="intfunctions">
-     <title>Internal Functions</title>
-!Idrivers/net/wan/z85230.c
-  </chapter>
-
-</book>
diff --git a/Documentation/networking/index.rst b/Documentation/networking/index.rst
index ff652ff279e8..b5bd87e01f52 100644
--- a/Documentation/networking/index.rst
+++ b/Documentation/networking/index.rst
@@ -7,6 +7,7 @@ Contents:
    :maxdepth: 2
 
    kapi
+   z8530book
 
 .. only::  subproject
 
diff --git a/Documentation/networking/z8530book.rst b/Documentation/networking/z8530book.rst
new file mode 100644
index 000000000000..31032ee36081
--- /dev/null
+++ b/Documentation/networking/z8530book.rst
@@ -0,0 +1,257 @@
+=======================
+Z8530 Programming Guide
+=======================
+
+:Author: Alan Cox
+
+Introduction
+============
+
+The Z85x30 family synchronous/asynchronous controller chips are used on
+a large number of cheap network interface cards. The kernel provides a
+core interface layer that is designed to make it easy to provide WAN
+services using this chip.
+
+The current driver only support synchronous operation. Merging the
+asynchronous driver support into this code to allow any Z85x30 device to
+be used as both a tty interface and as a synchronous controller is a
+project for Linux post the 2.4 release
+
+Driver Modes
+============
+
+The Z85230 driver layer can drive Z8530, Z85C30 and Z85230 devices in
+three different modes. Each mode can be applied to an individual channel
+on the chip (each chip has two channels).
+
+The PIO synchronous mode supports the most common Z8530 wiring. Here the
+chip is interface to the I/O and interrupt facilities of the host
+machine but not to the DMA subsystem. When running PIO the Z8530 has
+extremely tight timing requirements. Doing high speeds, even with a
+Z85230 will be tricky. Typically you should expect to achieve at best
+9600 baud with a Z8C530 and 64Kbits with a Z85230.
+
+The DMA mode supports the chip when it is configured to use dual DMA
+channels on an ISA bus. The better cards tend to support this mode of
+operation for a single channel. With DMA running the Z85230 tops out
+when it starts to hit ISA DMA constraints at about 512Kbits. It is worth
+noting here that many PC machines hang or crash when the chip is driven
+fast enough to hold the ISA bus solid.
+
+Transmit DMA mode uses a single DMA channel. The DMA channel is used for
+transmission as the transmit FIFO is smaller than the receive FIFO. it
+gives better performance than pure PIO mode but is nowhere near as ideal
+as pure DMA mode.
+
+Using the Z85230 driver
+=======================
+
+The Z85230 driver provides the back end interface to your board. To
+configure a Z8530 interface you need to detect the board and to identify
+its ports and interrupt resources. It is also your problem to verify the
+resources are available.
+
+Having identified the chip you need to fill in a struct z8530_dev,
+which describes each chip. This object must exist until you finally
+shutdown the board. Firstly zero the active field. This ensures nothing
+goes off without you intending it. The irq field should be set to the
+interrupt number of the chip. (Each chip has a single interrupt source
+rather than each channel). You are responsible for allocating the
+interrupt line. The interrupt handler should be set to
+:c:func:`z8530_interrupt()`. The device id should be set to the
+z8530_dev structure pointer. Whether the interrupt can be shared or not
+is board dependent, and up to you to initialise.
+
+The structure holds two channel structures. Initialise chanA.ctrlio and
+chanA.dataio with the address of the control and data ports. You can or
+this with Z8530_PORT_SLEEP to indicate your interface needs the 5uS
+delay for chip settling done in software. The PORT_SLEEP option is
+architecture specific. Other flags may become available on future
+platforms, eg for MMIO. Initialise the chanA.irqs to &z8530_nop to
+start the chip up as disabled and discarding interrupt events. This
+ensures that stray interrupts will be mopped up and not hang the bus.
+Set chanA.dev to point to the device structure itself. The private and
+name field you may use as you wish. The private field is unused by the
+Z85230 layer. The name is used for error reporting and it may thus make
+sense to make it match the network name.
+
+Repeat the same operation with the B channel if your chip has both
+channels wired to something useful. This isn't always the case. If it is
+not wired then the I/O values do not matter, but you must initialise
+chanB.dev.
+
+If your board has DMA facilities then initialise the txdma and rxdma
+fields for the relevant channels. You must also allocate the ISA DMA
+channels and do any necessary board level initialisation to configure
+them. The low level driver will do the Z8530 and DMA controller
+programming but not board specific magic.
+
+Having initialised the device you can then call
+:c:func:`z8530_init()`. This will probe the chip and reset it into
+a known state. An identification sequence is then run to identify the
+chip type. If the checks fail to pass the function returns a non zero
+error code. Typically this indicates that the port given is not valid.
+After this call the type field of the z8530_dev structure is
+initialised to either Z8530, Z85C30 or Z85230 according to the chip
+found.
+
+Once you have called z8530_init you can also make use of the utility
+function :c:func:`z8530_describe()`. This provides a consistent
+reporting format for the Z8530 devices, and allows all the drivers to
+provide consistent reporting.
+
+Attaching Network Interfaces
+============================
+
+If you wish to use the network interface facilities of the driver, then
+you need to attach a network device to each channel that is present and
+in use. In addition to use the generic HDLC you need to follow some
+additional plumbing rules. They may seem complex but a look at the
+example hostess_sv11 driver should reassure you.
+
+The network device used for each channel should be pointed to by the
+netdevice field of each channel. The hdlc-> priv field of the network
+device points to your private data - you will need to be able to find
+your private data from this.
+
+The way most drivers approach this particular problem is to create a
+structure holding the Z8530 device definition and put that into the
+private field of the network device. The network device fields of the
+channels then point back to the network devices.
+
+If you wish to use the generic HDLC then you need to register the HDLC
+device.
+
+Before you register your network device you will also need to provide
+suitable handlers for most of the network device callbacks. See the
+network device documentation for more details on this.
+
+Configuring And Activating The Port
+===================================
+
+The Z85230 driver provides helper functions and tables to load the port
+registers on the Z8530 chips. When programming the register settings for
+a channel be aware that the documentation recommends initialisation
+orders. Strange things happen when these are not followed.
+
+:c:func:`z8530_channel_load()` takes an array of pairs of
+initialisation values in an array of u8 type. The first value is the
+Z8530 register number. Add 16 to indicate the alternate register bank on
+the later chips. The array is terminated by a 255.
+
+The driver provides a pair of public tables. The z8530_hdlc_kilostream
+table is for the UK 'Kilostream' service and also happens to cover most
+other end host configurations. The z8530_hdlc_kilostream_85230 table
+is the same configuration using the enhancements of the 85230 chip. The
+configuration loaded is standard NRZ encoded synchronous data with HDLC
+bitstuffing. All of the timing is taken from the other end of the link.
+
+When writing your own tables be aware that the driver internally tracks
+register values. It may need to reload values. You should therefore be
+sure to set registers 1-7, 9-11, 14 and 15 in all configurations. Where
+the register settings depend on DMA selection the driver will update the
+bits itself when you open or close. Loading a new table with the
+interface open is not recommended.
+
+There are three standard configurations supported by the core code. In
+PIO mode the interface is programmed up to use interrupt driven PIO.
+This places high demands on the host processor to avoid latency. The
+driver is written to take account of latency issues but it cannot avoid
+latencies caused by other drivers, notably IDE in PIO mode. Because the
+drivers allocate buffers you must also prevent MTU changes while the
+port is open.
+
+Once the port is open it will call the rx_function of each channel
+whenever a completed packet arrived. This is invoked from interrupt
+context and passes you the channel and a network buffer (struct
+sk_buff) holding the data. The data includes the CRC bytes so most
+users will want to trim the last two bytes before processing the data.
+This function is very timing critical. When you wish to simply discard
+data the support code provides the function
+:c:func:`z8530_null_rx()` to discard the data.
+
+To active PIO mode sending and receiving the ``
+    z8530_sync_open`` is called. This expects to be passed the network
+device and the channel. Typically this is called from your network
+device open callback. On a failure a non zero error status is returned.
+The :c:func:`z8530_sync_close()` function shuts down a PIO
+channel. This must be done before the channel is opened again and before
+the driver shuts down and unloads.
+
+The ideal mode of operation is dual channel DMA mode. Here the kernel
+driver will configure the board for DMA in both directions. The driver
+also handles ISA DMA issues such as controller programming and the
+memory range limit for you. This mode is activated by calling the
+:c:func:`z8530_sync_dma_open()` function. On failure a non zero
+error value is returned. Once this mode is activated it can be shut down
+by calling the :c:func:`z8530_sync_dma_close()`. You must call
+the close function matching the open mode you used.
+
+The final supported mode uses a single DMA channel to drive the transmit
+side. As the Z85C30 has a larger FIFO on the receive channel this tends
+to increase the maximum speed a little. This is activated by calling the
+``z8530_sync_txdma_open
+    ``. This returns a non zero error code on failure. The
+:c:func:`z8530_sync_txdma_close()` function closes down the Z8530
+interface from this mode.
+
+Network Layer Functions
+=======================
+
+The Z8530 layer provides functions to queue packets for transmission.
+The driver internally buffers the frame currently being transmitted and
+one further frame (in order to keep back to back transmission running).
+Any further buffering is up to the caller.
+
+The function :c:func:`z8530_queue_xmit()` takes a network buffer
+in sk_buff format and queues it for transmission. The caller must
+provide the entire packet with the exception of the bitstuffing and CRC.
+This is normally done by the caller via the generic HDLC interface
+layer. It returns 0 if the buffer has been queued and non zero values
+for queue full. If the function accepts the buffer it becomes property
+of the Z8530 layer and the caller should not free it.
+
+The function :c:func:`z8530_get_stats()` returns a pointer to an
+internally maintained per interface statistics block. This provides most
+of the interface code needed to implement the network layer get_stats
+callback.
+
+Porting The Z8530 Driver
+========================
+
+The Z8530 driver is written to be portable. In DMA mode it makes
+assumptions about the use of ISA DMA. These are probably warranted in
+most cases as the Z85230 in particular was designed to glue to PC type
+machines. The PIO mode makes no real assumptions.
+
+Should you need to retarget the Z8530 driver to another architecture the
+only code that should need changing are the port I/O functions. At the
+moment these assume PC I/O port accesses. This may not be appropriate
+for all platforms. Replacing :c:func:`z8530_read_port()` and
+``z8530_write_port
+    `` is intended to be all that is required to port this driver layer.
+
+Known Bugs And Assumptions
+==========================
+
+Interrupt Locking
+    The locking in the driver is done via the global cli/sti lock. This
+    makes for relatively poor SMP performance. Switching this to use a
+    per device spin lock would probably materially improve performance.
+
+Occasional Failures
+    We have reports of occasional failures when run for very long
+    periods of time and the driver starts to receive junk frames. At the
+    moment the cause of this is not clear.
+
+Public Functions Provided
+=========================
+
+.. kernel-doc:: drivers/net/wan/z85230.c
+   :export:
+
+Internal Functions
+==================
+
+.. kernel-doc:: drivers/net/wan/z85230.c
+   :internal:
-- 
2.9.3
