hwmon: Add driver for MPS MPQ8785 Synchronous Step-Down Converter

Add support for mpq8785 device from Monolithic Power Systems, Inc.
(MPS) vendor. This is synchronous step-down controller.

Signed-off-by: Charles Hsu <ythsu0511@gmail.com>
Link: https://lore.kernel.org/r/20240131074822.2962078-2-ythsu0511@gmail.com
[groeck: probe_new --> probe; add MODULE_IMPORT_NS(PMBUS)]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

2 files changed, 95 insertions, 0 deletions

diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index 8f73badecba11c..9ac087dd3e78d1 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -164,6 +164,7 @@ Hardware Monitoring Kernel Drivers
    mp2975
    mp5023
    mp5990
+   mpq8785
    nct6683
    nct6775
    nct7802
diff --git a/Documentation/hwmon/mpq8785.rst b/Documentation/hwmon/mpq8785.rst
new file mode 100644
index 00000000000000..bf8176b8708687
--- /dev/null
+++ b/Documentation/hwmon/mpq8785.rst
@@ -0,0 +1,94 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+Kernel driver mpq8785
+=======================
+
+Supported chips:
+
+  * MPS MPQ8785
+
+    Prefix: 'mpq8785'
+
+Author: Charles Hsu <ythsu0511@gmail.com>
+
+Description
+-----------
+
+The MPQ8785 is a fully integrated, PMBus-compatible, high-frequency, synchronous
+buck converter. The MPQ8785 offers a very compact solution that achieves up to
+40A output current per phase, with excellent load and line regulation over a
+wide input supply range. The MPQ8785 operates at high efficiency over a wide
+output current load range.
+
+The PMBus interface provides converter configurations and key parameters
+monitoring.
+
+The MPQ8785 adopts MPS's proprietary multi-phase digital constant-on-time (MCOT)
+control, which provides fast transient response and eases loop stabilization.
+The MCOT scheme also allows multiple MPQ8785 devices to be connected in parallel
+with excellent current sharing and phase interleaving for high-current
+applications.
+
+Fully integrated protection features include over-current protection (OCP),
+over-voltage protection (OVP), under-voltage protection (UVP), and
+over-temperature protection (OTP).
+
+The MPQ8785 requires a minimal number of readily available, standard external
+components, and is available in a TLGA (5mmx6mm) package.
+
+Device compliant with:
+
+- PMBus rev 1.3 interface.
+
+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**
+
+**in1_crit**
+
+**in1_crit_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_max**
+
+**curr1_max_alarm**
+
+**curr1_crit**
+
+**curr1_crit_alarm**
+
+The driver provides the following attributes for temperature:
+
+**temp1_input**
+
+**temp1_max**
+
+**temp1_max_alarm**
+
+**temp1_crit**
+
+**temp1_crit_alarm**