hwmon: Add TSC1641 I2C power monitor driver

Add a driver for the ST Microelectronics TSC1641 16-bit high-precision
power monitor. The driver supports reading bus voltage, current, power,
and temperature. Sysfs attributes are exposed for shunt resistor and
update interval. The driver integrates with the hwmon subsystem and
supports optional ALERT pin polarity configuration.

Signed-off-by: Igor Reznichenko <igor@reznichenko.net>
Link: https://lore.kernel.org/r/20251105201406.1210856-3-igor@reznichenko.net
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/index.rst

@@ -256,6 +256,7 @@ Hardware Monitoring Kernel Drivers
    tps40422
    tps53679
    tps546d24
+   tsc1641
    twl4030-madc-hwmon
    ucd9000
    ucd9200

Documentation/hwmon/tsc1641.rst

@@ -0,0 +1,87 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+Kernel driver tsc1641
+=====================
+
+Supported chips:
+
+  * ST TSC1641
+
+    Prefix: 'tsc1641'
+
+    Addresses scanned: -
+
+    Datasheet:
+	https://www.st.com/resource/en/datasheet/tsc1641.pdf
+
+Author:
+	- Igor Reznichenko <igor@reznichenko.net>
+
+
+Description
+-----------
+
+The TSC1641 is a high-precision current, voltage, power, and temperature
+monitoring analog front-end (AFE). It monitors bidirectional current into a
+shunt resistor and load voltage up to 60 V in a synchronized way. Digital bus
+interface is I2C/SMbus. The TSC1641 allows the assertion of several alerts
+regarding the voltage, current, power and temperature.
+
+Usage Notes
+-----------
+
+The TSC1641 driver requires the value of the external shunt resistor to
+correctly compute current and power measurements. The resistor value, in
+micro-ohms, should be provided either through the device tree property
+"shunt-resistor-micro-ohms" or via writable sysfs attribute "shunt_resistor".
+Please refer to the Documentation/devicetree/bindings/hwmon/st,tsc1641.yaml
+for bindings if the device tree is used.
+
+Supported range of shunt resistor values is from 100 uOhm to 655.35 mOhm, in
+10 uOhm steps.
+When selecting the value keep in mind device maximum DC power measurement is
+1600W. See datasheet p.22 for ST recommendations on selecting shunt value.
+
+If the shunt resistor value is not specified in the device tree, the driver
+initializes it to 1000 uOhm by default. Users may configure the correct shunt
+resistor value at runtime by writing to the "shunt_resistor" sysfs attribute.
+
+The driver only supports continuous operating mode.
+Measurement ranges:
+
+================ ===============================================================
+Current          Bidirectional, dependent on shunt
+Bus voltage      0-60V
+Maximum DC power 1600W
+Temperature      -40C to +125C
+================ ===============================================================
+
+Sysfs entries
+-------------
+
+==================== ===========================================================
+in0_input            bus voltage (mV)
+in0_max              bus voltage max alarm limit (mV)
+in0_max_alarm        bus voltage max alarm limit exceeded
+in0_min              bus voltage min alarm limit (mV)
+in0_min_alarm        bus voltage min alarm limit exceeded
+
+curr1_input          current measurement (mA)
+curr1_max            current max alarm limit (mA)
+curr1_max_alarm      current max alarm limit exceeded
+curr1_min            current min alarm limit (mA)
+curr1_min_alarm      current min alarm limit exceeded
+
+power1_input         power measurement (uW)
+power1_max           power max alarm limit (uW)
+power1_max_alarm     power max alarm limit exceeded
+
+shunt_resistor       shunt resistor value (uOhms)
+
+temp1_input          temperature measurement (mdegC)
+temp1_max            temperature max alarm limit (mdegC)
+temp1_max_alarm      temperature max alarm limit exceeded
+
+update_interval      data conversion time (1 - 33ms), longer conversion time
+                     corresponds to higher effective resolution in bits
+==================== ===========================================================

drivers/hwmon/Kconfig

@@ -2434,6 +2434,18 @@ config SENSORS_TMP513
 	  This driver can also be built as a module. If so, the module
 	  will be called tmp513.
 
+config SENSORS_TSC1641
+	tristate "ST Microelectronics TSC1641 Power Monitor"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  If you say yes here you get support for TSC1641 power  monitor chip.
+	  The TSC1641 driver is configured for the default configuration of
+	  the part except temperature is enabled by default.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called tsc1641.
+
 config SENSORS_VEXPRESS
 	tristate "Versatile Express"
 	depends on VEXPRESS_CONFIG

drivers/hwmon/Makefile

@@ -233,6 +233,7 @@ obj-$(CONFIG_SENSORS_TMP401)	+= tmp401.o
 obj-$(CONFIG_SENSORS_TMP421)	+= tmp421.o
 obj-$(CONFIG_SENSORS_TMP464)	+= tmp464.o
 obj-$(CONFIG_SENSORS_TMP513)	+= tmp513.o
+obj-$(CONFIG_SENSORS_TSC1641)	+= tsc1641.o
 obj-$(CONFIG_SENSORS_VEXPRESS)	+= vexpress-hwmon.o
 obj-$(CONFIG_SENSORS_VIA_CPUTEMP)+= via-cputemp.o
 obj-$(CONFIG_SENSORS_VIA686A)	+= via686a.o