hwmon: (pmbus/d1u74t) Add Murata D1U74T PSU driver

Add PMBUS driver for Murata D1U74T power supplies.

Signed-off-by: Abdurrahman Hussain <abdurrahman@nexthop.ai>
Link: https://lore.kernel.org/r/20260514-d1u74t-v4-2-1f1ee7b002ec@nexthop.ai
[groeck: Dropped inappropriate tags; added missing include files]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/d1u74t.rst

@@ -0,0 +1,81 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+Kernel driver d1u74t
+====================
+
+Supported chips:
+
+  * Murata D1U74T
+
+    Prefix: 'd1u74t'
+
+    Addresses scanned: -
+
+    Datasheet: Publicly available at the Murata website
+
+Authors:
+    Abdurrahman Hussain <abdurrahman@nexthop.ai>
+
+
+Description
+-----------
+
+This driver implements support for Murata D1U74T Power Supply with
+PMBus support.
+
+The driver is a client driver to the core PMBus driver.
+Please see Documentation/hwmon/pmbus.rst for details on PMBus client drivers.
+
+
+Usage Notes
+-----------
+
+This driver does not auto-detect devices. You will have to instantiate the
+devices explicitly. Please see Documentation/i2c/instantiating-devices.rst for
+details.
+
+
+Sysfs entries
+-------------
+
+======================= ======================================================
+curr1_label		"iin"
+curr1_input		Measured input current
+curr1_alarm		Input current alarm
+curr1_rated_max		Maximum rated input current
+
+curr2_label		"iout1"
+curr2_input		Measured output current
+curr2_max		Maximum output current
+curr2_max_alarm		Output current high alarm
+curr2_crit		Critical high output current
+curr2_crit_alarm	Output current critical high alarm
+curr2_rated_max		Maximum rated output current
+
+in1_label		"vin"
+in1_input		Measured input voltage
+in1_alarm		Input voltage alarm
+in1_rated_min		Minimum rated input voltage
+in1_rated_max		Maximum rated input voltage
+
+in2_label		"vout1"
+in2_input		Measured output voltage
+in2_alarm		Output voltage alarm
+in2_rated_min		Minimum rated output voltage
+in2_rated_max		Maximum rated output voltage
+
+power1_label		"pin"
+power1_input		Measured input power
+power1_alarm		Input power alarm
+power1_rated_max	Maximum rated input power
+
+temp[1-3]_input		Measured temperature
+temp[1-3]_max		Maximum temperature
+temp[1-3]_max_alarm	Maximum temperature alarm
+temp[1-3]_rated_max	Maximum rated temperature
+
+fan1_alarm		Fan 1 warning
+fan1_fault		Fan 1 fault
+fan1_input		Fan 1 speed in RPM
+fan1_target		Fan 1 target
+======================= ======================================================

Documentation/hwmon/index.rst

@@ -61,6 +61,7 @@ Hardware Monitoring Kernel Drivers
    corsair-psu
    cros_ec_hwmon
    crps
+   d1u74t
    da9052
    da9055
    dell-smm-hwmon

MAINTAINERS

@@ -18284,6 +18284,13 @@ F:	drivers/mux/
 F:	include/dt-bindings/mux/
 F:	include/linux/mux/
 
+MURATA D1U74T PSU DRIVER
+M:	Abdurrahman Hussain <abdurrahman@nexthop.ai>
+L:	linux-hwmon@vger.kernel.org
+S:	Maintained
+F:	Documentation/hwmon/d1u74t.rst
+F:	drivers/hwmon/pmbus/d1u74t.c
+
 MUSB MULTIPOINT HIGH SPEED DUAL-ROLE CONTROLLER
 M:	Bin Liu <b-liu@ti.com>
 L:	linux-usb@vger.kernel.org

drivers/hwmon/pmbus/Kconfig

@@ -113,6 +113,15 @@ config SENSORS_CRPS
 	  This driver can also be built as a module. If so, the module will
 	  be called crps.
 
+config SENSORS_D1U74T
+	tristate "Murata D1U74T Power Supply"
+	help
+	  If you say yes here you get hardware monitoring support for the Murata
+	  D1U74T Power Supply.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called d1u74t.
+
 config SENSORS_DELTA_AHE50DC_FAN
 	tristate "Delta AHE-50DC fan control module"
 	help

drivers/hwmon/pmbus/Makefile

@@ -80,3 +80,4 @@ obj-$(CONFIG_SENSORS_XDPE1A2G7B)	+= xdpe1a2g7b.o
 obj-$(CONFIG_SENSORS_ZL6100)	+= zl6100.o
 obj-$(CONFIG_SENSORS_PIM4328)	+= pim4328.o
 obj-$(CONFIG_SENSORS_CRPS)	+= crps.o
+obj-$(CONFIG_SENSORS_D1U74T)	+= d1u74t.o

drivers/hwmon/pmbus/d1u74t.c

@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright 2026 Nexthop Systems.
+ */
+
+#include <linux/i2c.h>
+#include <linux/of.h>
+#include <linux/module.h>
+#include <linux/pmbus.h>
+#include <linux/string.h>
+
+#include "pmbus.h"
+
+static const struct i2c_device_id d1u74t_id[] = {
+	{ "d1u74t" },
+	{},
+};
+MODULE_DEVICE_TABLE(i2c, d1u74t_id);
+
+static struct pmbus_driver_info d1u74t_info = {
+	.pages = 1,
+	/* PSU uses default linear data format. */
+	.func[0] = PMBUS_HAVE_PIN | PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT |
+		   PMBUS_HAVE_IIN | PMBUS_HAVE_VIN | PMBUS_HAVE_STATUS_INPUT |
+		   PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT | PMBUS_HAVE_TEMP |
+		   PMBUS_HAVE_TEMP2 | PMBUS_HAVE_TEMP3 |
+		   PMBUS_HAVE_STATUS_TEMP | PMBUS_HAVE_FAN12 |
+		   PMBUS_HAVE_STATUS_FAN12,
+};
+
+static int d1u74t_probe(struct i2c_client *client)
+{
+	char buf[I2C_SMBUS_BLOCK_MAX + 2] = { 0 };
+	struct device *dev = &client->dev;
+	int rc;
+
+	rc = i2c_smbus_read_block_data(client, PMBUS_MFR_ID, buf);
+	if (rc < 0)
+		return dev_err_probe(dev, rc, "Failed to read PMBUS_MFR_ID\n");
+
+	if (rc != 9 || strncmp(buf, "Murata-PS", 9)) {
+		buf[rc] = '\0';
+		return dev_err_probe(dev, -ENODEV,
+				     "Unsupported Manufacturer ID '%s'\n",
+				     buf);
+	}
+
+	rc = i2c_smbus_read_block_data(client, PMBUS_MFR_MODEL, buf);
+	if (rc < 0)
+		return dev_err_probe(dev, rc,
+				     "Failed to read PMBUS_MFR_MODEL\n");
+
+	if (rc < 8 || strncmp(buf, "D1U74T-W", 8)) {
+		buf[rc] = '\0';
+		return dev_err_probe(dev, -ENODEV, "Model '%s' not supported\n",
+				     buf);
+	}
+
+	rc = pmbus_do_probe(client, &d1u74t_info);
+	if (rc)
+		return dev_err_probe(dev, rc, "Failed to probe\n");
+
+	return 0;
+}
+
+static const struct of_device_id d1u74t_of_match[] = {
+	{
+		.compatible = "murata,d1u74t",
+	},
+	{},
+};
+MODULE_DEVICE_TABLE(of, d1u74t_of_match);
+
+static struct i2c_driver d1u74t_driver = {
+	.driver = {
+		.name = "d1u74t",
+		.of_match_table = d1u74t_of_match,
+	},
+	.probe = d1u74t_probe,
+	.id_table = d1u74t_id,
+};
+
+module_i2c_driver(d1u74t_driver);
+
+MODULE_AUTHOR("Abdurrahman Hussain");
+MODULE_DESCRIPTION("PMBus driver for Murata D1U74T-W power supplies");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("PMBUS");