Commit 4eb174be authored by Michael Hennerich's avatar Michael Hennerich Committed by Linus Torvalds

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: default avatarMichael Hennerich <>
Signed-off-by: default avatarChris Verges <>
Signed-off-by: default avatarMike Frysinger <>
Cc: Jean Delvare <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 00b55864
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.
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.
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
# echo 10 > eeprom0
# cat eeprom0
# cat rdac0
# echo 3 > rdac0
# cat rdac0
......@@ -13,6 +13,20 @@ menuconfig MISC_DEVICES
config AD525X_DPOT
tristate "Analog Devices AD525x Digital Potentiometers"
depends on I2C && SYSFS
If you say yes here, you get support for the Analog Devices
AD5258, AD5259, AD5251, AD5252, AD5253, AD5254 and AD5255
digital potentiometer chips.
See Documentation/misc-devices/ad525x_dpot.txt for the
userspace interface.
This driver can also be built as a module. If so, the module
will be called ad525x_dpot.
config ATMEL_PWM
tristate "Atmel AT32/AT91 PWM support"
depends on AVR32 || ARCH_AT91SAM9263 || ARCH_AT91SAM9RL || ARCH_AT91CAP9
......@@ -4,6 +4,7 @@
obj-$(CONFIG_IBM_ASM) += ibmasm/
obj-$(CONFIG_HDPU_FEATURES) += hdpuftrs/
obj-$(CONFIG_AD525X_DPOT) += ad525x_dpot.o
obj-$(CONFIG_ATMEL_PWM) += atmel_pwm.o
obj-$(CONFIG_ATMEL_SSC) += atmel-ssc.o
obj-$(CONFIG_ATMEL_TCLIB) += atmel_tclib.o
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