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authorbgardner@wabtec.com <bgardner@wabtec.com>2005-06-07 08:55:38 -0500
committerGreg Kroah-Hartman <gregkh@suse.de>2005-06-21 21:52:05 -0700
commit69dd204b6b45987dbf9ce7058cd238d355865281 (patch)
treee033f9697109d4a411e5c6707b0e6991e00ede7f /Documentation/i2c
parent10c08f8100ee2c4d27b862635574cdf4ef439e67 (diff)
downloadlinux-linaro-stable-69dd204b6b45987dbf9ce7058cd238d355865281.tar.gz
[PATCH] I2C: add new pca9539 driver
This is an i2c driver for the Philips PCA9539 (16 bit I/O port). It uses the new i2c-sysfs interfaces. The patch includes documentation. It depends on the patch that renames "i2c-sysfs.h" to "hwmon-sysfs.h" Signed-off-by: Ben Gardner <bgardner@wabtec.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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+Kernel driver pca9539
+=====================
+
+Supported chips:
+ * Philips PCA9539
+ Prefix: 'pca9539'
+ Addresses scanned: 0x74 - 0x77
+ Datasheet:
+ http://www.semiconductors.philips.com/acrobat/datasheets/PCA9539_2.pdf
+
+Author: Ben Gardner <bgardner@wabtec.com>
+
+
+Description
+-----------
+
+The Philips PCA9539 is a 16 bit low power I/O device.
+All 16 lines can be individually configured as an input or output.
+The input sense can also be inverted.
+The 16 lines are split between two bytes.
+
+
+Sysfs entries
+-------------
+
+Each is a byte that maps to the 8 I/O bits.
+A '0' suffix is for bits 0-7, while '1' is for bits 8-15.
+
+input[01] - read the current value
+output[01] - sets the output value
+direction[01] - direction of each bit: 1=input, 0=output
+invert[01] - toggle the input bit sense
+
+input reads the actual state of the line and is always available.
+The direction defaults to input for all channels.
+
+
+General Remarks
+---------------
+
+Note that each output, direction, and invert entry controls 8 lines.
+You should use the read, modify, write sequence.
+For example. to set output bit 0 of 1.
+ val=$(cat output0)
+ val=$(( $val | 1 ))
+ echo $val > output0
+