hwmon: (pmbus) Add support for MPS Multi-phase mp5023

Add support for mp5023 device from Monolithic Power Systems, Inc. (MPS)
vendor. This is a Hot-Swap Controller.

Signed-off-by: Howard Chiu <howard.chiu@quantatw.com>
Link: https://lore.kernel.org/r/HKAPR04MB400349AA406694FB976D78D096709@HKAPR04MB4003.apcprd04.prod.outlook.com
[groeck: Added MODULE_IMPORT_NS, entry in index.rst]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
diff --git a/Documentation/hwmon/mp5023.rst b/Documentation/hwmon/mp5023.rst
new file mode 100644
index 0000000..af5ab13
--- /dev/null
+++ b/Documentation/hwmon/mp5023.rst
@@ -0,0 +1,84 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver mp5023
+====================
+
+Supported chips:
+
+  * MPS MP5023
+
+    Prefix: 'mp5023'
+
+  * Datasheet
+
+    Publicly available at the MPS website : https://www.monolithicpower.com/en/mp5023.html
+
+Author:
+
+	Howard Chiu <howard.chiu@quantatw.com>
+
+Description
+-----------
+
+This driver implements support for Monolithic Power Systems, Inc. (MPS)
+MP5023 Hot-Swap Controller.
+
+Device complaint with:
+
+- PMBus rev 1.3 interface.
+
+Device supports direct format for reading input voltage, output voltage,
+output current, input power and temperature.
+
+The driver exports the following attributes via the 'sysfs' files
+for input voltage:
+
+**in1_input**
+
+**in1_label**
+
+**in1_max**
+
+**in1_max_alarm**
+
+**in1_min**
+
+**in1_min_alarm**
+
+The driver provides the following attributes for output voltage:
+
+**in2_input**
+
+**in2_label**
+
+**in2_alarm**
+
+The driver provides the following attributes for output current:
+
+**curr1_input**
+
+**curr1_label**
+
+**curr1_alarm**
+
+**curr1_max**
+
+The driver provides the following attributes for input power:
+
+**power1_input**
+
+**power1_label**
+
+**power1_alarm**
+
+The driver provides the following attributes for temperature:
+
+**temp1_input**
+
+**temp1_max**
+
+**temp1_max_alarm**
+
+**temp1_crit**
+
+**temp1_crit_alarm**