hwmon: Add driver for ltc2991

Add support for LTC2991 Octal I2C Voltage, Current, and Temperature
Monitor.

The LTC2991 is used to monitor system temperatures, voltages and
currents. Through the I2C serial interface, the eight monitors can
individually measure supply voltages and can be paired for
differential measurements of current sense resistors or temperature
sensing transistors. Additional measurements include internal
temperature and internal VCC.

Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
Link: https://lore.kernel.org/r/20231026103413.27800-2-antoniu.miclaus@analog.com
[groeck: Fixed up documentation warning]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/index.rst

@@ -121,6 +121,7 @@ Hardware Monitoring Kernel Drivers
    ltc2947
    ltc2978
    ltc2990
+   ltc2991
    ltc3815
    ltc4151
    ltc4215

Documentation/hwmon/ltc2991.rst

@@ -0,0 +1,43 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver ltc2991
+=====================
+
+Supported chips:
+
+  * Analog Devices LTC2991
+
+    Prefix: 'ltc2991'
+
+    Addresses scanned: I2C 0x48 - 0x4f
+
+    Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/2991ff.pdf
+
+Authors:
+
+  - Antoniu Miclaus <antoniu.miclaus@analog.com>
+
+
+Description
+-----------
+
+This driver supports hardware monitoring for Analog Devices LTC2991 Octal I2C
+Voltage, Current and Temperature Monitor.
+
+The LTC2991 is used to monitor system temperatures, voltages and currents.
+Through the I2C serial interface, the eight monitors can individually measure
+supply voltages and can be paired for differential measurements of current sense
+resistors or temperature sensing transistors. Additional measurements include
+internal temperatureand internal VCC.
+
+
+sysfs-Interface
+---------------
+
+The following attributes are supported. Limits are read-only.
+
+=============== =================
+inX_input:      voltage input
+currX_input:    current input
+tempX_input:    temperature input
+=============== =================

MAINTAINERS

@@ -12458,6 +12458,14 @@ F:	drivers/hwmon/ltc2947-i2c.c
 F:	drivers/hwmon/ltc2947-spi.c
 F:	drivers/hwmon/ltc2947.h
 
+LTC2991 HARDWARE MONITOR DRIVER
+M:	Antoniu Miclaus <antoniu.miclaus@analog.com>
+L:	linux-hwmon@vger.kernel.org
+S:	Supported
+W:	https://ez.analog.com/linux-software-drivers
+F:	Documentation/devicetree/bindings/hwmon/adi,ltc2991.yaml
+F:	drivers/hwmon/ltc2991.c
+
 LTC2983 IIO TEMPERATURE DRIVER
 M:	Nuno Sá <nuno.sa@analog.com>
 L:	linux-iio@vger.kernel.org

drivers/hwmon/Kconfig

@@ -942,6 +942,17 @@ config SENSORS_LTC2990
 	  This driver can also be built as a module. If so, the module will
 	  be called ltc2990.
 
+config SENSORS_LTC2991
+	tristate "Analog Devices LTC2991"
+	depends on I2C
+	help
+	  If you say yes here you get support for Analog Devices LTC2991
+	  Octal I2C Voltage, Current, and Temperature Monitor. The LTC2991
+	  supports a combination of voltage, current and temperature monitoring.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called ltc2991.
+
 config SENSORS_LTC2992
 	tristate "Linear Technology LTC2992"
 	depends on I2C

drivers/hwmon/Makefile

@@ -127,6 +127,7 @@ obj-$(CONFIG_SENSORS_LTC2947)	+= ltc2947-core.o
 obj-$(CONFIG_SENSORS_LTC2947_I2C) += ltc2947-i2c.o
 obj-$(CONFIG_SENSORS_LTC2947_SPI) += ltc2947-spi.o
 obj-$(CONFIG_SENSORS_LTC2990)	+= ltc2990.o
+obj-$(CONFIG_SENSORS_LTC2991)	+= ltc2991.o
 obj-$(CONFIG_SENSORS_LTC2992)	+= ltc2992.o
 obj-$(CONFIG_SENSORS_LTC4151)	+= ltc4151.o
 obj-$(CONFIG_SENSORS_LTC4215)	+= ltc4215.o