hwmon: (pmbus) Add support for MPS Multi-phase mp2888 controller

Add support for mp2888 device from Monolithic Power Systems, Inc. (MPS)
vendor. This is a digital, multi-phase, pulse-width modulation
controller.

This device supports:
- One power rail.
- Programmable Multi-Phase up to 10 Phases.
- PWM-VID Interface
- One pages 0 for telemetry.
- Programmable pins for PMBus Address.
- Built-In EEPROM to Store Custom Configurations.
- Can configured VOUT readout in direct or VID format and allows
  setting of different formats on rails 1 and 2. For VID the following
  protocols are available: VR13 mode with 5-mV DAC; VR13 mode with
  10-mV DAC, IMVP9 mode with 5-mV DAC.
Signed-off-by: Vadim Pasternak <vadimp@nvidia.com>
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/r/20210511055619.118104-3-vadimp@nvidia.com
[groeck: Add MODULE_IMPORT_NS]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/mp2888.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver mp2888
+====================
+
+Supported chips:
+
+  * MPS MP12254
+
+    Prefix: 'mp2888'
+
+Author:
+
+	Vadim Pasternak <vadimp@nvidia.com>
+
+Description
+-----------
+
+This driver implements support for Monolithic Power Systems, Inc. (MPS)
+vendor dual-loop, digital, multi-phase controller MP2888.
+
+This device: supports:
+
+- One power rail.
+- Programmable Multi-Phase up to 10 Phases.
+- PWM-VID Interface
+- One pages 0 for telemetry.
+- Programmable pins for PMBus Address.
+- Built-In EEPROM to Store Custom Configurations.
+
+Device complaint with:
+
+- PMBus rev 1.3 interface.
+
+Device supports direct format for reading output current, output voltage,
+input and output power and temperature.
+Device supports linear format for reading input voltage and input power.
+
+The driver provides the next attributes for the current:
+
+- for current out input and maximum alarm;
+- for phase current: input and label.
+
+The driver exports the following attributes via the 'sysfs' files, where:
+
+- 'n' is number of configured phases (from 1 to 10);
+- index 1 for "iout";
+- indexes 2 ... 1 + n for phases.
+
+**curr[1-{1+n}]_input**
+
+**curr[1-{1+n}]_label**
+
+**curr1_max**
+
+**curr1_max_alarm**
+
+The driver provides the next attributes for the voltage:
+
+- for voltage in: input, low and high critical thresholds, low and high
+  critical alarms;
+- for voltage out: input and high alarm;
+
+The driver exports the following attributes via the 'sysfs' files, where
+
+**in1_crit**
+
+**in1_crit_alarm**
+
+**in1_input**
+
+**in1_label**
+
+**in1_min**
+
+**in1_min_alarm**
+
+**in2_alarm**
+
+**in2_input**
+
+**in2_label**
+
+The driver provides the next attributes for the power:
+
+- for power in alarm and input.
+- for power out: cap, cap alarm an input.
+
+The driver exports the following attributes via the 'sysfs' files, where
+- indexes 1 for "pin";
+- indexes 2 for "pout";
+
+**power1_alarm**
+
+**power1_input**
+
+**power1_label**
+
+**power2_input**
+
+**power2_label**
+
+**power2_max**
+
+**power2_max_alarm**
+
+The driver provides the next attributes for the temperature:
+
+**temp1_input**
+
+**temp1_max**
+
+**temp1_max_alarm**

drivers/hwmon/pmbus/Kconfig

@@ -249,6 +249,15 @@ config SENSORS_MAX8688
 	  This driver can also be built as a module. If so, the module will
 	  be called max8688.
 
+config SENSORS_MP2888
+	tristate "MPS MP2888"
+	help
+	  If you say yes here you get hardware monitoring support for MPS
+	  MP2888 Digital, Multi-Phase, Pulse-Width Modulation Controller.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called mp2888.
+
 config SENSORS_MP2975
 	tristate "MPS MP2975"
 	help

drivers/hwmon/pmbus/Makefile

@@ -28,6 +28,7 @@ obj-$(CONFIG_SENSORS_MAX20751)	+= max20751.o
 obj-$(CONFIG_SENSORS_MAX31785)	+= max31785.o
 obj-$(CONFIG_SENSORS_MAX34440)	+= max34440.o
 obj-$(CONFIG_SENSORS_MAX8688)	+= max8688.o
+obj-$(CONFIG_SENSORS_MP2888)	+= mp2888.o
 obj-$(CONFIG_SENSORS_MP2975)	+= mp2975.o
 obj-$(CONFIG_SENSORS_PM6764TR)	+= pm6764tr.o
 obj-$(CONFIG_SENSORS_PXE1610)	+= pxe1610.o