Bartosz Golaszewski 72a87a47a8 hwmon: (ina2xx) implement update_interval attribute for ina226
This attribute allows to configure the update interval of ina226. Although
the bus and shunt voltage conversion times remain hardcoded to 1.1 ms, we can
now modify said interval by changing the averaging rate.

While we're at it - add an additional variable to ina2xx_data, which holds
the current configuration settings - this way we'll be able to restore the
configuration in case of an unexpected chip reset.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
2015-01-25 21:23:59 -08:00

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Kernel driver ina2xx
====================
Supported chips:
* Texas Instruments INA219
Prefix: 'ina219'
Addresses: I2C 0x40 - 0x4f
Datasheet: Publicly available at the Texas Instruments website
http://www.ti.com/
* Texas Instruments INA220
Prefix: 'ina220'
Addresses: I2C 0x40 - 0x4f
Datasheet: Publicly available at the Texas Instruments website
http://www.ti.com/
* Texas Instruments INA226
Prefix: 'ina226'
Addresses: I2C 0x40 - 0x4f
Datasheet: Publicly available at the Texas Instruments website
http://www.ti.com/
* Texas Instruments INA230
Prefix: 'ina230'
Addresses: I2C 0x40 - 0x4f
Datasheet: Publicly available at the Texas Instruments website
http://www.ti.com/
Author: Lothar Felten <l-felten@ti.com>
Description
-----------
The INA219 is a high-side current shunt and power monitor with an I2C
interface. The INA219 monitors both shunt drop and supply voltage, with
programmable conversion times and filtering.
The INA220 is a high or low side current shunt and power monitor with an I2C
interface. The INA220 monitors both shunt drop and supply voltage.
The INA226 is a current shunt and power monitor with an I2C interface.
The INA226 monitors both a shunt voltage drop and bus supply voltage.
The INA230 is a high or low side current shunt and power monitor with an I2C
interface. The INA230 monitors both a shunt voltage drop and bus supply voltage.
The shunt value in micro-ohms can be set via platform data or device tree at
compile-time or via the shunt_resistor attribute in sysfs at run-time. Please
refer to the Documentation/devicetree/bindings/i2c/ina2xx.txt for bindings
if the device tree is used.
Additionally ina226 supports update_interval attribute as described in
Documentation/hwmon/sysfs-interface. Internally the interval is the sum of
bus and shunt voltage conversion times multiplied by the averaging rate. We
don't touch the conversion times and only modify the number of averages. The
lower limit of the update_interval is 2 ms, the upper limit is 2253 ms.
The actual programmed interval may vary from the desired value.