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hwmon: (pmbus/lm25066) Support configurable sense resistor values 

The appropriate mantissa values for the lm25066 family's direct-format
current and power readings are a function of the sense resistor
employed between the SENSE and VIN pins of the chip.  Instead of
assuming that resistance is always the same 1mOhm as used in the
datasheet, allow it to be configured via a device-tree property
("shunt-resistor-micro-ohms").

Signed-off-by: Zev Weiss <zev@bewilderbeest.net>
Link: https://lore.kernel.org/r/20210928092242.30036-8-zev@bewilderbeest.net
[groeck: Fixed checkpatch warnings]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
This commit is contained in:
Zev Weiss 2021-09-28 02:22:41 -07:00 committed by Guenter Roeck
parent b7792f3ea3
commit 94ee5fcc24
2 changed files with 13 additions and 0 deletions
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2
Documentation/hwmon/lm25066.rst
View File

@ -79,6 +79,8 @@ This driver does not auto-detect devices. You will have to instantiate the
devices explicitly. Please see Documentation/i2c/instantiating-devices.rst for
details.
The shunt (sense) resistor value can be configured by a device tree property;
see Documentation/devicetree/bindings/hwmon/pmbus/ti,lm25066.yaml for details.
Platform data support
---------------------

11
drivers/hwmon/pmbus/lm25066.c
View File

@ -458,6 +458,7 @@ MODULE_DEVICE_TABLE(of, lm25066_of_match);
static int lm25066_probe(struct i2c_client *client)
{
int config;
u32 shunt;
struct lm25066_data *data;
struct pmbus_driver_info *info;
const struct __coeff *coeff;
@ -534,6 +535,16 @@ static int lm25066_probe(struct i2c_client *client)
info->b[PSC_POWER] = coeff[PSC_POWER].b;
}
/*
* Values in the TI datasheets are normalized for a 1mOhm sense
* resistor; assume that unless DT specifies a value explicitly.
*/
if (of_property_read_u32(client->dev.of_node, "shunt-resistor-micro-ohms", &shunt))
shunt = 1000;
info->m[PSC_CURRENT_IN] = info->m[PSC_CURRENT_IN] * shunt / 1000;
info->m[PSC_POWER] = info->m[PSC_POWER] * shunt / 1000;
return pmbus_do_probe(client, info);
}