linux-stable/Documentation/hwmon/ina3221.rst
Nicolin Chen 2057bdfb71 hwmon: (ina3221) Add summation feature support
This patch implements the summation feature of INA3221, mainly the
SCC (enabling) and SF (warning flag) bits of MASK_ENABLE register,
INA3221_SHUNT_SUM (summation of shunt voltages) register, and the
INA3221_CRIT_SUM (its critical alert setting) register.

Although the summation feature allows user to select which channels
to be added to the result, as an initial support, this patch simply
selects all channels by default, with one only condition: all shunt
resistor values need to be the same. This is because the summation
of current channels can be only accurately calculated, using shunt
voltage sum register, if all shunt resistors are equivalent.

Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
Link: https://lore.kernel.org/r/20191016235702.22039-1-nicoleotsuka@gmail.com
[groeck: summation->sum in documentation and label]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
2019-11-06 14:37:19 -08:00

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ReStructuredText

Kernel driver ina3221
=====================
Supported chips:
* Texas Instruments INA3221
Prefix: 'ina3221'
Addresses: I2C 0x40 - 0x43
Datasheet: Publicly available at the Texas Instruments website
http://www.ti.com/
Author: Andrew F. Davis <afd@ti.com>
Description
-----------
The Texas Instruments INA3221 monitors voltage, current, and power on the high
side of up to three D.C. power supplies. The INA3221 monitors both shunt drop
and supply voltage, with programmable conversion times and averaging, current
and power are calculated host-side from these.
Sysfs entries
-------------
======================= =======================================================
in[123]_label Voltage channel labels
in[123]_enable Voltage channel enable controls
in[123]_input Bus voltage(mV) channels
curr[123]_input Current(mA) measurement channels
shunt[123]_resistor Shunt resistance(uOhm) channels
curr[123]_crit Critical alert current(mA) setting, activates the
corresponding alarm when the respective current
is above this value
curr[123]_crit_alarm Critical alert current limit exceeded
curr[123]_max Warning alert current(mA) setting, activates the
corresponding alarm when the respective current
average is above this value.
curr[123]_max_alarm Warning alert current limit exceeded
in[456]_input Shunt voltage(uV) for channels 1, 2, and 3 respectively
in7_input Sum of shunt voltage(uV) channels
in7_label Channel label for sum of shunt voltage
curr4_input Sum of current(mA) measurement channels,
(only available when all channels use the same resistor
value for their shunt resistors)
curr4_crit Critical alert current(mA) setting for sum of current
measurements, activates the corresponding alarm
when the respective current is above this value
(only effective when all channels use the same resistor
value for their shunt resistors)
curr4_crit_alarm Critical alert current limit exceeded for sum of
current measurements.
samples Number of samples using in the averaging mode.
Supports the list of number of samples:
1, 4, 16, 64, 128, 256, 512, 1024
update_interval Data conversion time in millisecond, following:
update_interval = C x S x (BC + SC)
* C: number of enabled channels
* S: number of samples
* BC: bus-voltage conversion time in millisecond
* SC: shunt-voltage conversion time in millisecond
Affects both Bus- and Shunt-voltage conversion time.
Note that setting update_interval to 0ms sets both BC
and SC to 140 us (minimum conversion time).
======================= =======================================================