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acrn-kernel/Documentation/w1/masters/omap-hdq

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hdq: documentation for OMAP HDQ Add a brief document about omap2430/3430 HDQ/1-wire driver. Signed-off-by: Madhusudhan Chikkature<madhu.cr@ti.com> Acked-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-11-13 05:27:12 +08:00
Kernel driver for omap HDQ/1-wire module.
========================================
Supported chips:
================
HDQ/1-wire controller on the TI OMAP 2430/3430 platforms.
A useful link about HDQ basics:
===============================
Documentation: update broken web addresses. Below you will find an updated version from the original series bunching all patches into one big patch updating broken web addresses that are located in Documentation/* Some of the addresses date as far far back as 1995 etc... so searching became a bit difficult, the best way to deal with these is to use web.archive.org to locate these addresses that are outdated. Now there are also some addresses pointing to .spec files some are located, but some(after searching on the companies site)where still no where to be found. In this case I just changed the address to the company site this way the users can contact the company and they can locate them for the users. Signed-off-by: Justin P. Mattock <justinmattock@gmail.com> Signed-off-by: Thomas Weber <weber@corscience.de> Signed-off-by: Mike Frysinger <vapier.adi@gmail.com> Cc: Paulo Marques <pmarques@grupopie.com> Cc: Randy Dunlap <rdunlap@xenotime.net> Cc: Michael Neuling <mikey@neuling.org> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
2010-07-24 11:51:24 +08:00
http://focus.ti.com/lit/an/slua408a/slua408a.pdf
hdq: documentation for OMAP HDQ Add a brief document about omap2430/3430 HDQ/1-wire driver. Signed-off-by: Madhusudhan Chikkature<madhu.cr@ti.com> Acked-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-11-13 05:27:12 +08:00
Description:
============
The HDQ/1-Wire module of TI OMAP2430/3430 platforms implement the hardware
protocol of the master functions of the Benchmark HDQ and the Dallas
Semiconductor 1-Wire protocols. These protocols use a single wire for
communication between the master (HDQ/1-Wire controller) and the slave
(HDQ/1-Wire external compliant device).
A typical application of the HDQ/1-Wire module is the communication with battery
monitor (gas gauge) integrated circuits.
The controller supports operation in both HDQ and 1-wire mode. The essential
difference between the HDQ and 1-wire mode is how the slave device responds to
initialization pulse.In HDQ mode, the firmware does not require the host to
create an initialization pulse to the slave.However, the slave can be reset by
using an initialization pulse (also referred to as a break pulse).The slave
does not respond with a presence pulse as it does in the 1-Wire protocol.
Remarks:
========
The driver (drivers/w1/masters/omap_hdq.c) supports the HDQ mode of the
controller. In this mode, as we can not read the ID which obeys the W1
spec(family:id:crc), a module parameter can be passed to the driver which will
be used to calculate the CRC and pass back an appropriate slave ID to the W1
core.
By default the master driver and the BQ slave i/f
driver(drivers/w1/slaves/w1_bq27000.c) sets the ID to 1.
Please note to load both the modules with a different ID if required, but note
that the ID used should be same for both master and slave driver loading.
e.g:
insmod omap_hdq.ko W1_ID=2
inamod w1_bq27000.ko F_ID=2