[PATCH v2 0/2] hwmon: Add Murata D1U74T-W PSU driver

[PATCH v2 0/2] hwmon: Add Murata D1U74T-W PSU driver

[Abdurrahman Hussain]

This series adds a PMBus driver for the Murata D1U74T-W AC/DC power
supply unit, used in some Open Compute Project platforms.

The PSU is PMBus-compliant and uses the linear data format. The driver
exposes:

  - input/output voltage, current and power telemetry,
  - three temperature sensors,
  - dual fan tachometer monitoring,

through the standard hwmon/pmbus sysfs interface. Probe verifies the
PMBUS_MFR_ID and PMBUS_MFR_MODEL fields before binding so the driver
only attaches to actual D1U74T-W hardware.

Patch 1 adds the compatible string to trivial-devices.yaml. The
binding declares only compatible and reg (no regulators, no supplies),
so a standalone binding file is not warranted.

Patch 2 adds the driver, hwmon documentation, Kconfig/Makefile entries
and MAINTAINERS section.

Signed-off-by: Abdurrahman Hussain <abdurrahman@nexthop.ai>
---
Changes in v2:
- Patch 1: move the binding into trivial-devices.yaml rather than
  carrying a standalone murata,d1u74t.yaml. The device only declares
  compatible and reg, with no regulators or supplies, so the
  standalone binding was not warranted (Conor Dooley review).
- Patch 2: fix the d1u74t.rst title underline (was 18 '=' chars under
  a 20-char title, docutils warning from the kernel test robot).
- Link to v1: https://patch.msgid.link/20260511-d1u74t-v1-0-623c2bc1532a@nexthop.ai

To: Rob Herring <robh@kernel.org>
To: Krzysztof Kozlowski <krzk+dt@kernel.org>
To: Conor Dooley <conor+dt@kernel.org>
To: Abdurrahman Hussain <abdurrahman@nexthop.ai>
To: Guenter Roeck <linux@roeck-us.net>
To: Jonathan Corbet <corbet@lwn.net>
To: Shuah Khan <skhan@linuxfoundation.org>
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-hwmon@vger.kernel.org
Cc: linux-doc@vger.kernel.org

---
Abdurrahman Hussain (2):
      dt-bindings: trivial-devices: Add Murata D1U74T PSU
      hwmon: (pmbus/d1u74t) Add Murata D1U74T PSU driver

 .../devicetree/bindings/trivial-devices.yaml       |  2 +
 Documentation/hwmon/d1u74t.rst                     | 97 ++++++++++++++++++++++
 Documentation/hwmon/index.rst                      |  1 +
 MAINTAINERS                                        |  7 ++
 drivers/hwmon/pmbus/Kconfig                        |  9 ++
 drivers/hwmon/pmbus/Makefile                       |  1 +
 drivers/hwmon/pmbus/d1u74t.c                       | 85 +++++++++++++++++++
 7 files changed, 202 insertions(+)
---
base-commit: 5d6919055dec134de3c40167a490f33c74c12581
change-id: 20260511-d1u74t-c0cba8f1c344

Best regards,
--  
Abdurrahman Hussain <abdurrahman@nexthop.ai>

[PATCH v2 1/2] dt-bindings: trivial-devices: Add Murata D1U74T PSU

[Abdurrahman Hussain]

The Murata D1U74T-W is a PMBus-compliant AC/DC power supply unit. The
binding only declares the compatible string and i2c reg, with no
additional properties (no regulators, no supplies), so add it to
trivial-devices.yaml rather than carrying a standalone binding file.

Signed-off-by: Abdurrahman Hussain <abdurrahman@nexthop.ai>
---
 Documentation/devicetree/bindings/trivial-devices.yaml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/trivial-devices.yaml b/Documentation/devicetree/bindings/trivial-devices.yaml
index 23fd4513933a..19c8c7220858 100644
--- a/Documentation/devicetree/bindings/trivial-devices.yaml
+++ b/Documentation/devicetree/bindings/trivial-devices.yaml
@@ -352,6 +352,8 @@ properties:
           - mps,mp9941
             # Monolithic Power Systems Inc. digital step-down converter mp9945
           - mps,mp9945
+            # Murata D1U74T-W power supply unit
+          - murata,d1u74t
             # Temperature sensor with integrated fan control
           - national,lm63
             # Temperature sensor with integrated fan control

-- 
2.53.0

[PATCH v2 2/2] hwmon: (pmbus/d1u74t) Add Murata D1U74T PSU driver

[Abdurrahman Hussain]

Add PMBUS driver for Murata D1U74T power supplies.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202605122253.zInzmUeX-lkp@intel.com/
Signed-off-by: Abdurrahman Hussain <abdurrahman@nexthop.ai>
---
 Documentation/hwmon/d1u74t.rst | 97 ++++++++++++++++++++++++++++++++++++++++++
 Documentation/hwmon/index.rst  |  1 +
 MAINTAINERS                    |  7 +++
 drivers/hwmon/pmbus/Kconfig    |  9 ++++
 drivers/hwmon/pmbus/Makefile   |  1 +
 drivers/hwmon/pmbus/d1u74t.c   | 85 ++++++++++++++++++++++++++++++++++++
 6 files changed, 200 insertions(+)

diff --git a/Documentation/hwmon/d1u74t.rst b/Documentation/hwmon/d1u74t.rst
new file mode 100644
index 000000000000..7362e56e76a7
--- /dev/null
+++ b/Documentation/hwmon/d1u74t.rst
@@ -0,0 +1,97 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+Kernel driver d1u74t
+====================
+
+Supported chips:
+
+  * Murata D1U74T
+
+    Prefix: 'd1u74t'
+
+    Addresses scanned: -
+
+    Datasheet: Only available under NDA.
+
+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_max		Maximum input current
+curr1_max_alarm		Input maximum current high alarm
+curr1_crit		Critical high input current
+curr1_crit_alarm	Input critical current high 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 maximum current high alarm
+curr2_crit		Critical high output current
+curr2_crit_alarm	Output critical current high alarm
+curr2_rated_max		Maximum rated output current
+
+in1_label		"vin"
+in1_input		Measured input voltage
+in1_crit		Critical input over voltage
+in1_crit_alarm		Critical input over voltage alarm
+in1_max			Maximum input over voltage
+in1_max_alarm		Maximum input over voltage alarm
+in1_rated_min		Minimum rated input voltage
+in1_rated_max		Maximum rated input voltage
+
+in2_label		"vout1"
+in2_input		Measured input voltage
+in2_crit		Critical input over voltage
+in2_crit_alarm		Critical input over voltage alarm
+in2_lcrit		Critical input under voltage fault
+in2_lcrit_alarm		Critical input under voltage fault alarm
+in2_max			Maximum input over voltage
+in2_max_alarm		Maximum input over voltage alarm
+in2_min			Minimum input under voltage warning
+in2_min_alarm		Minimum input under voltage warning alarm
+in2_rated_min		Minimum rated input voltage
+in2_rated_max		Maximum rated input voltage
+
+power1_label		"pin"
+power1_input		Measured input power
+power1_alarm		Input power high alarm
+power1_max  		Maximum input power
+power1_rated_max	Maximum rated input power
+
+temp[1-3]_input		Measured temperature
+temp[1-3]_crit 		Critical temperature
+temp[1-3]_crit_alarm	Critical temperature alarm
+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.
+======================= ======================================================
diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index 8b655e5d6b68..97b1ef65b1c1 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -60,6 +60,7 @@ Hardware Monitoring Kernel Drivers
    corsair-psu
    cros_ec_hwmon
    crps
+   d1u74t
    da9052
    da9055
    dell-smm-hwmon
diff --git a/MAINTAINERS b/MAINTAINERS
index b2040011a386..28ca8e035312 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6803,6 +6803,13 @@ S:	Maintained
 F:	Documentation/hwmon/crps.rst
 F:	drivers/hwmon/pmbus/crps.c
 
+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
+
 CRYPTO API
 M:	Herbert Xu <herbert@gondor.apana.org.au>
 M:	"David S. Miller" <davem@davemloft.net>
diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
index 8f4bff375ecb..ee93b22d2887 100644
--- a/drivers/hwmon/pmbus/Kconfig
+++ b/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
diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
index 7129b62bc00f..8cf7d3075371 100644
--- a/drivers/hwmon/pmbus/Makefile
+++ b/drivers/hwmon/pmbus/Makefile
@@ -76,3 +76,4 @@ 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
diff --git a/drivers/hwmon/pmbus/d1u74t.c b/drivers/hwmon/pmbus/d1u74t.c
new file mode 100644
index 000000000000..3127e0e5a23d
--- /dev/null
+++ b/drivers/hwmon/pmbus/d1u74t.c
@@ -0,0 +1,85 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright 2026 Nexthop Systems.
+ */
+
+#include <linux/i2c.h>
+#include <linux/of.h>
+#include <linux/pmbus.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';
+		dev_err(dev, "Unsupported Manufacturer ID '%s'\n", buf);
+		return -ENODEV;
+	}
+
+	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 (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");

-- 
2.53.0

Re: [PATCH v2 1/2] dt-bindings: trivial-devices: Add Murata D1U74T PSU

[Conor Dooley]

[-- Attachment #1: Type: text/plain, Size: 75 bytes --]

Acked-by: Conor Dooley <conor.dooley@microchip.com>
pw-bot: not-applicable

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]

Re: [PATCH v2 2/2] hwmon: (pmbus/d1u74t) Add Murata D1U74T PSU driver

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 3 potential issue(s) to consider:
- [Low] Brittle validation logic due to missing read length check for PMBUS_MFR_MODEL.
- [Low] Copy-paste errors in sysfs documentation for `in2_*` attributes.
- [Low] MAINTAINERS file entry breaks alphabetical ordering.
--

commit ec60b1738fafe62da18eefb7e9b1f9a12b6a9113
Author: Abdurrahman Hussain <abdurrahman@nexthop.ai>

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

This commit adds a new PMBus driver for Murata D1U74T power supplies. It
registers the device with the hwmon subsystem and provides documentation for
the driver's sysfs attributes.

Closes: https://lore.kernel.org/oe-kbuild-all/202605122253.zInzmUeX-lkp@intel.com/

> diff --git a/Documentation/hwmon/d1u74t.rst b/Documentation/hwmon/d1u74t.rst
> new file mode 100644
> index 0000000000000..7362e56e76a71
> --- /dev/null
> +++ b/Documentation/hwmon/d1u74t.rst
[ ... ]
> +in1_rated_min		Minimum rated input voltage
> +in1_rated_max		Maximum rated input voltage
> +
> +in2_label		"vout1"
> +in2_input		Measured input voltage

This isn't a bug, but is there a copy-paste error in these descriptions?
Should these be documented as 'output voltage' instead of 'input voltage',
since the label is "vout1"?

> +in2_crit		Critical input over voltage
> +in2_crit_alarm		Critical input over voltage alarm
> +in2_lcrit		Critical input under voltage fault
> +in2_lcrit_alarm		Critical input under voltage fault alarm
> +in2_max			Maximum input over voltage
> +in2_max_alarm		Maximum input over voltage alarm
> +in2_min			Minimum input under voltage warning
> +in2_min_alarm		Minimum input under voltage warning alarm
> +in2_rated_min		Minimum rated input voltage
> +in2_rated_max		Maximum rated input voltage
[ ... ]
> diff --git a/MAINTAINERS b/MAINTAINERS
> index b2040011a3865..28ca8e0353124 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -6803,6 +6803,13 @@ S:	Maintained
>  F:	Documentation/hwmon/crps.rst
>  F:	drivers/hwmon/pmbus/crps.c
>  
> +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
> +
>  CRYPTO API

This isn't a bug, but does this entry break the alphabetical ordering? It
places an 'M' entry immediately before the 'C' section for CRYPTO API.

>  M:	Herbert Xu <herbert@gondor.apana.org.au>
[ ... ]
> diff --git a/drivers/hwmon/pmbus/d1u74t.c b/drivers/hwmon/pmbus/d1u74t.c
> new file mode 100644
> index 0000000000000..3127e0e5a23de
> --- /dev/null
> +++ b/drivers/hwmon/pmbus/d1u74t.c
[ ... ]
> +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';
> +		dev_err(dev, "Unsupported Manufacturer ID '%s'\n", buf);
> +		return -ENODEV;
> +	}
> +
> +	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 (strncmp(buf, "D1U74T-W", 8)) {

Is there a missing check for the read length in rc here?

If a short read occurs, could strncmp() evaluate the newly read bytes
combined with stale memory leftover from the previous PMBUS_MFR_ID read?

> +		buf[rc] = '\0';
> +		return dev_err_probe(dev, -ENODEV, "Model '%s' not supported\n",
> +				     buf);
> +	}
> +
> +	rc = pmbus_do_probe(client, &d1u74t_info);
[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260512-d1u74t-v2-0-431d00fbb1c4@nexthop.ai?part=2