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| author | Michael Hennerich <michael.hennerich@analog.com> | 2009-12-15 05:00:15 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-12-15 19:53:25 +0300 |
| commit | 4eb174bee6f8623fed1af0072f1bebfc3b513a52 (patch) | |
| tree | 9357e122a1fc99a881a0091623acc8fe8ce22112 /Documentation/misc-devices/ad525x_dpot.txt | |
| parent | 00b55864bb37200d7f05143c44f5e2edfc8c4578 (diff) | |
| download | linux-4eb174bee6f8623fed1af0072f1bebfc3b513a52.tar.xz | |
ad525x_dpot: new driver for AD525x digital potentiometers
This driver supports the non-volatile digital potentiometers via I2C:
AD5258, AD5259, AD5251, AD5252, AD5253, AD5254, and AD5255
It provides a sysfs interface to each device for reading/writing which
is documented in Documentation/misc-devices/ad525x_dpot.txt.
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Chris Verges <chrisv@cyberswitching.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Cc: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/misc-devices/ad525x_dpot.txt')
| -rw-r--r-- | Documentation/misc-devices/ad525x_dpot.txt | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/Documentation/misc-devices/ad525x_dpot.txt b/Documentation/misc-devices/ad525x_dpot.txt new file mode 100644 index 000000000000..0c9413b1cbf3 --- /dev/null +++ b/Documentation/misc-devices/ad525x_dpot.txt @@ -0,0 +1,57 @@ +--------------------------------- + AD525x Digital Potentiometers +--------------------------------- + +The ad525x_dpot driver exports a simple sysfs interface. This allows you to +work with the immediate resistance settings as well as update the saved startup +settings. Access to the factory programmed tolerance is also provided, but +interpretation of this settings is required by the end application according to +the specific part in use. + +--------- + Files +--------- + +Each dpot device will have a set of eeprom, rdac, and tolerance files. How +many depends on the actual part you have, as will the range of allowed values. + +The eeprom files are used to program the startup value of the device. + +The rdac files are used to program the immediate value of the device. + +The tolerance files are the read-only factory programmed tolerance settings +and may vary greatly on a part-by-part basis. For exact interpretation of +this field, please consult the datasheet for your part. This is presented +as a hex file for easier parsing. + +----------- + Example +----------- + +Locate the device in your sysfs tree. This is probably easiest by going into +the common i2c directory and locating the device by the i2c slave address. + + # ls /sys/bus/i2c/devices/ + 0-0022 0-0027 0-002f + +So assuming the device in question is on the first i2c bus and has the slave +address of 0x2f, we descend (unrelated sysfs entries have been trimmed). + + # ls /sys/bus/i2c/devices/0-002f/ + eeprom0 rdac0 tolerance0 + +You can use simple reads/writes to access these files: + + # cd /sys/bus/i2c/devices/0-002f/ + + # cat eeprom0 + 0 + # echo 10 > eeprom0 + # cat eeprom0 + 10 + + # cat rdac0 + 5 + # echo 3 > rdac0 + # cat rdac0 + 3 |