[PATCH v6 1/2] dt-bindings: hwmon: add STEF48H28

[PATCH v6 1/2] dt-bindings: hwmon: add STEF48H28

[Charles Hsu]

Add device tree bindings for the hot-swap controller STEF48H28.

Signed-off-by: Charles Hsu <hsu.yungteng@gmail.com>
---
Changes in v6:
- Fix patch formatting issues.

Changes in v5:
- Move the change list into the commit message.

Changes in v4:
- Fix an incorrect datasheet URL and update it to the correct reference.

Changes in v3:
- Move the STEF48H28 Device Tree binding from
  trivial-devices.yaml to pmbus/stef48h28.yaml.

Changes in v2:
- Fix the entry in trivial-devices.yaml by correcting the comment
  and compatible string ordering.
---
 .../bindings/hwmon/pmbus/st,stef48h28.yaml    | 43 +++++++++++++++++++
 1 file changed, 43 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/pmbus/st,stef48h28.yaml

diff --git a/Documentation/devicetree/bindings/hwmon/pmbus/st,stef48h28.yaml b/Documentation/devicetree/bindings/hwmon/pmbus/st,stef48h28.yaml
new file mode 100644
index 000000000000..c6a4b02bcd84
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/pmbus/st,stef48h28.yaml
@@ -0,0 +1,43 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/hwmon/pmbus/st,stef48h28.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: STMicroelectronics hot-swap controller with PMBus interface
+
+maintainers:
+  - Charles Hsu <hsu.yungteng@gmail.com>
+
+description: |
+  The STEF48H28 is an advanced 30A integrated electronic fuse for
+  the 9-80V DC power lines.
+
+  Datasheet:
+    https://www.st.com/resource/en/data_brief/stef48h28.pdf
+
+properties:
+  compatible:
+    enum:
+      - st,stef48h28
+
+  reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        pmic@11 {
+            compatible = "st,stef48h28";
+            reg = <0x11>;
+        };
+    };
--
2.34.1

[PATCH v6 2/2] hwmon: pmbus: add support for STEF48H28

[Charles Hsu]

Add support for STEF48H28 hot-swap controller.

Signed-off-by: Charles Hsu <hsu.yungteng@gmail.com>
---
 Documentation/hwmon/index.rst     |  1 +
 Documentation/hwmon/stef48h28.rst | 73 ++++++++++++++++++++++++++++++
 MAINTAINERS                       |  7 +++
 drivers/hwmon/pmbus/Kconfig       |  9 ++++
 drivers/hwmon/pmbus/Makefile      |  1 +
 drivers/hwmon/pmbus/stef48h28.c   | 75 +++++++++++++++++++++++++++++++
 6 files changed, 166 insertions(+)
 create mode 100644 Documentation/hwmon/stef48h28.rst
 create mode 100644 drivers/hwmon/pmbus/stef48h28.c

diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index 85d7a686883e..c682751a1fe3 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -233,6 +233,7 @@ Hardware Monitoring Kernel Drivers
    shtc1
    sis5595
    sl28cpld
+   stef48h28
    smpro-hwmon
    smsc47b397
    smsc47m192
diff --git a/Documentation/hwmon/stef48h28.rst b/Documentation/hwmon/stef48h28.rst
new file mode 100644
index 000000000000..00bef9e55651
--- /dev/null
+++ b/Documentation/hwmon/stef48h28.rst
@@ -0,0 +1,73 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver stef48h28
+=======================
+
+Supported chips:
+
+  * Analog Devices STEF48H28
+
+    Prefix: 'stef48h28'
+
+    Addresses scanned: -
+
+    Datasheet: https://www.st.com/resource/en/data_brief/stef48h28.pdf
+
+Author:
+
+  - Charles Hsu <hsu.yungteng@gmail.com>
+
+
+Description
+-----------
+
+The STEF48H28 is a 30 A integrated e-fuse for 9-80 V DC power rails.
+It provides inrush control, undervoltage/overvoltage lockout and
+overcurrent protection using an adaptive (I x t) scheme that permits
+short high-current pulses typical of CPU/GPU loads.
+
+The device offers an analog current-monitor output and an on-chip
+temperature-monitor signal for system supervision. Startup behavior is
+programmable through insertion-delay and soft-start settings.
+
+Additional features include power-good indication, self-diagnostics,
+thermal shutdown and a PMBus interface for telemetry and status
+reporting.
+
+Platform data support
+---------------------
+
+The driver supports standard PMBus driver platform data.
+
+Sysfs entries
+-------------
+
+=========================================================
+in1_label		"vin".
+in1_input		Measured voltage. From READ_VIN register.
+in1_min			Minimum Voltage. From VIN_UV_WARN_LIMIT register.
+in1_max			Maximum voltage. From VIN_OV_WARN_LIMIT register.
+
+in2_label		"vout1".
+in2_input		Measured voltage. From READ_VOUT register.
+in2_min			Minimum Voltage. From VOUT_UV_WARN_LIMIT register.
+in2_max			Maximum voltage. From VOUT_OV_WARN_LIMIT register.
+
+curr1_label "iin".
+curr1_input Measured current. From READ_IIN register.
+
+curr2_label "iout1".
+curr2_input Measured current. From READ_IOUT register.
+
+power1_label		"pin"
+power1_input		Measured input power. From READ_PIN register.
+
+power2_label		"pout1"
+power2_input		Measured output power. From READ_POUT register.
+
+temp1_input		Measured temperature. From READ_TEMPERATURE_1 register.
+temp1_max		Maximum temperature. From OT_WARN_LIMIT register.
+temp1_crit		Critical high temperature. From OT_FAULT_LIMIT register.
+
+temp2_input		Measured temperature. From READ_TEMPERATURE_2 register.
+=========================================================
diff --git a/MAINTAINERS b/MAINTAINERS
index d701a4d5b00e..be6b6e9ee79b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -24665,6 +24665,13 @@ S:	Maintained
 F:	Documentation/devicetree/bindings/power/supply/st,stc3117.yaml
 F:	drivers/power/supply/stc3117_fuel_gauge.c

+ST STEF48H28 DRIVER
+M:	Charles Hsu	<hsu.yungteng@gmail.com>
+L:	linux-hwmon@vger.kernel.org
+S:	Maintained
+F:	Documentation/hwmon/stef48h28.rst
+F:	drivers/hwmon/pmbus/stef48h28.c
+
 ST STM32 FIREWALL
 M:	Gatien Chevallier <gatien.chevallier@foss.st.com>
 S:	Maintained
diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
index f3fb94cebf1a..29ea8ba98b8b 100644
--- a/drivers/hwmon/pmbus/Kconfig
+++ b/drivers/hwmon/pmbus/Kconfig
@@ -576,6 +576,15 @@ config SENSORS_Q54SJ108A2
 	  This driver can also be built as a module. If so, the module will
 	  be called q54sj108a2.

+config SENSORS_STEF48H28
+    tristate "ST STEF48H28"
+	help
+	  If you say yes here you get hardware monitoring support for ST
+	  STEF48H28.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called stef48h28.
+
 config SENSORS_STPDDC60
 	tristate "ST STPDDC60"
 	help
diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
index 349a89b6d92e..b2497f1d7bd9 100644
--- a/drivers/hwmon/pmbus/Makefile
+++ b/drivers/hwmon/pmbus/Makefile
@@ -56,6 +56,7 @@ obj-$(CONFIG_SENSORS_PLI1209BC)	+= pli1209bc.o
 obj-$(CONFIG_SENSORS_PM6764TR)	+= pm6764tr.o
 obj-$(CONFIG_SENSORS_PXE1610)	+= pxe1610.o
 obj-$(CONFIG_SENSORS_Q54SJ108A2)	+= q54sj108a2.o
+obj-$(CONFIG_SENSORS_STEF48H28)	+= stef48h28.o
 obj-$(CONFIG_SENSORS_STPDDC60)	+= stpddc60.o
 obj-$(CONFIG_SENSORS_TDA38640)	+= tda38640.o
 obj-$(CONFIG_SENSORS_TPS25990)	+= tps25990.o
diff --git a/drivers/hwmon/pmbus/stef48h28.c b/drivers/hwmon/pmbus/stef48h28.c
new file mode 100644
index 000000000000..4bde2215697c
--- /dev/null
+++ b/drivers/hwmon/pmbus/stef48h28.c
@@ -0,0 +1,75 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Hardware monitoring driver for STMicroelectronics digital controller stef48h28
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+
+#include "pmbus.h"
+
+static struct pmbus_driver_info stef48h28_info = {
+	.pages = 1,
+	.format[PSC_VOLTAGE_IN] = direct,
+	.format[PSC_VOLTAGE_OUT] = direct,
+	.format[PSC_CURRENT_IN] = direct,
+	.format[PSC_CURRENT_OUT] = direct,
+	.format[PSC_POWER] = direct,
+	.format[PSC_TEMPERATURE] = direct,
+	.m[PSC_VOLTAGE_IN] = 50,
+	.b[PSC_VOLTAGE_IN] = 0,
+	.R[PSC_VOLTAGE_IN] = 0,
+	.m[PSC_VOLTAGE_OUT] = 50,
+	.b[PSC_VOLTAGE_OUT] = 0,
+	.R[PSC_VOLTAGE_OUT] = 0,
+	.m[PSC_CURRENT_IN] = 100,
+	.b[PSC_CURRENT_IN] = 0,
+	.R[PSC_CURRENT_IN] = 0,
+	.m[PSC_CURRENT_OUT] = 100,
+	.b[PSC_CURRENT_OUT] = 0,
+	.R[PSC_CURRENT_OUT] = 0,
+	.m[PSC_POWER] = 9765,
+	.b[PSC_POWER] = 0,
+	.R[PSC_POWER] = -3,
+	.m[PSC_TEMPERATURE] = 25,
+	.b[PSC_TEMPERATURE] = 500,
+	.R[PSC_TEMPERATURE] = 0,
+	.func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_IIN | PMBUS_HAVE_PIN
+		| PMBUS_HAVE_STATUS_INPUT | PMBUS_HAVE_TEMP | PMBUS_HAVE_TEMP2
+		| PMBUS_HAVE_STATUS_TEMP | PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT
+		| PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT | PMBUS_HAVE_POUT
+};
+
+static int stef48h28_probe(struct i2c_client *client)
+{
+	return pmbus_do_probe(client, &stef48h28_info);
+}
+
+static const struct i2c_device_id stef48h28_id[] = {
+	{"stef48h28"},
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, stef48h28_id);
+
+static const struct of_device_id __maybe_unused stef48h28_of_match[] = {
+	{.compatible = "st,stef48h28"},
+	{}
+};
+
+static struct i2c_driver stef48h28_driver = {
+	.driver = {
+			.name = "stef48h28",
+			.of_match_table = of_match_ptr(stef48h28_of_match),
+			},
+	.probe = stef48h28_probe,
+	.id_table = stef48h28_id,
+};
+
+module_i2c_driver(stef48h28_driver);
+
+MODULE_AUTHOR("Charles Hsu <hsu.yungteng@gmail.com>");
+MODULE_DESCRIPTION("PMBus driver for ST stef48h28");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("PMBUS");
--
2.34.1

Re: [PATCH v6 1/2] dt-bindings: hwmon: add STEF48H28

[Krzysztof Kozlowski]

On 16/01/2026 09:58, Charles Hsu wrote:
> +properties:
> +  compatible:
> +    enum:
> +      - st,stef48h28
> +
> +  reg:
> +    maxItems: 1
> +
> +required:
> +  - compatible
> +  - reg
> +
> +unevaluatedProperties: false

This must be additionalProperties instead, see speeches/presentations
material or very explicit rule in writing bindings.

OTOH, this is so trivial now, that you could just add it to
trivial-devices schema.

Best regards,
Krzysztof