linux-kernel - [PATCH 2/2] bmp085: Add interface documentation and link to datasheet.

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Date:	Sat, 26 Jun 2010 13:10:24 +0200
From:	Christoph Mair <christoph.mair@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org,
	Jonathan Cameron <kernel@...23.retrosnub.co.uk>,
	Stefan Schmidt <stefan@...enfreihafen.org>,
	Datta Shubhrajyoti <shubhrajyoti@...com>,
	Christoph Mair <christoph.mair@...il.com>
Subject: [PATCH 2/2] bmp085: Add interface documentation and link to datasheet.

Signed-off-by: Christoph Mair <christoph.mair@...il.com>
---
 drivers/misc/bmp085.c |   27 +++++++++++++++++++++++++++
 1 files changed, 27 insertions(+), 0 deletions(-)

diff --git a/drivers/misc/bmp085.c b/drivers/misc/bmp085.c
index 16a2b2c..67ed8b2 100644
--- a/drivers/misc/bmp085.c
+++ b/drivers/misc/bmp085.c
@@ -1,5 +1,32 @@
 /*  Copyright (c) 2010  Christoph Mair <christoph.mair@...il.com>
 
+    This driver supports the bmp085 digital barometric pressure
+    and temperature sensor from Bosch Sensortec. The datasheet
+    is avaliable from their website:
+    http://www.bosch-sensortec.com/content/language1/downloads/BST-BMP085-DS000-05.pdf
+
+    A pressure measurement is issued by reading from pressure0_input.
+    The return value ranges from 30000 to 110000 pascal with a resulution
+    of 1 pascal (0.01 millibar) which enables measurements from 9000m above
+    to 500m below sea level.
+
+    The temperature can be read from temp0_input. Values range from
+    -400 to 850 representing the ambient temperature in degree celsius
+    multiplied by 10.The resolution is 0.1 celsius.
+
+    Because ambient pressure is temperature dependent, a temperature
+    measurement will be executed automatically even if the user is reading
+    from pressure0_input. This happens if the last temperature measurement
+    has been executed more then one second ago.
+
+    To decrease RMS noise from pressure measurements, the bmp085 can
+    autonomously calculate the average of up to eight samples. This is
+    set up by writing to the oversampling sysfs file. Accepted values
+    are 0, 1, 2 and 3. 2^x when x is the value written to this file
+    specifies the number of samples used to calculate the ambient pressure.
+    RMS noise is specified with six pascal (without averaging) and decreases
+    down to 3 pascal when using an oversampling setting of 3.
+
     This program 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
-- 
1.7.1

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