[PATCH 0/2] hwmon: Add support for MPS mp2985

[PATCH 0/2] hwmon: Add support for MPS mp2985

[wenswang]

From: Wensheng Wang <wenswang@yeah.net>

Add mp2985 driver in hwmon and add dt-bindings for it.

Wensheng Wang (2):
  dt-bindings: hwmon: Add MPS mp2985
  hwmon: add MP2985 driver

 .../devicetree/bindings/trivial-devices.yaml  |   2 +
 Documentation/hwmon/index.rst                 |   1 +
 Documentation/hwmon/mp2985.rst                | 151 ++++++++
 MAINTAINERS                                   |   7 +
 drivers/hwmon/pmbus/Kconfig                   |   9 +
 drivers/hwmon/pmbus/Makefile                  |   1 +
 drivers/hwmon/pmbus/mp2985.c                  | 355 ++++++++++++++++++
 7 files changed, 526 insertions(+)
 create mode 100644 Documentation/hwmon/mp2985.rst
 create mode 100644 drivers/hwmon/pmbus/mp2985.c

-- 
2.25.1

[PATCH 1/2] dt-bindings: hwmon: Add MPS mp2985

[wenswang]

From: Wensheng Wang <wenswang@yeah.net>

Add support for MPS mp2985 controller.

Signed-off-by: Wensheng Wang <wenswang@yeah.net>
---
 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 a482aeadcd44..d61482269352 100644
--- a/Documentation/devicetree/bindings/trivial-devices.yaml
+++ b/Documentation/devicetree/bindings/trivial-devices.yaml
@@ -325,6 +325,8 @@ properties:
           - mps,mp29612
             # Monolithic Power Systems Inc. multi-phase controller mp29816
           - mps,mp29816
+            # Monolithic Power Systems Inc. multi-phase controller mp2985
+          - mps,mp2985
             # Monolithic Power Systems Inc. multi-phase controller mp2993
           - mps,mp2993
             # Monolithic Power Systems Inc. hot-swap protection device
-- 
2.25.1

[PATCH 2/2] hwmon: add MP2985 driver

[wenswang]

From: Wensheng Wang <wenswang@yeah.net>

Add support for MPS mp2985 controller. This driver exposes
telemetry and limit value readings and writtings.

Signed-off-by: Wensheng Wang <wenswang@yeah.net>
---
 Documentation/hwmon/index.rst  |   1 +
 Documentation/hwmon/mp2985.rst | 151 ++++++++++++++
 MAINTAINERS                    |   7 +
 drivers/hwmon/pmbus/Kconfig    |   9 +
 drivers/hwmon/pmbus/Makefile   |   1 +
 drivers/hwmon/pmbus/mp2985.c   | 355 +++++++++++++++++++++++++++++++++
 6 files changed, 524 insertions(+)
 create mode 100644 Documentation/hwmon/mp2985.rst
 create mode 100644 drivers/hwmon/pmbus/mp2985.c

diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index b2ca8513cfcd..1b7007f41b39 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -183,6 +183,7 @@ Hardware Monitoring Kernel Drivers
    mp2925
    mp29502
    mp2975
+   mp2985
    mp2993
    mp5023
    mp5920
diff --git a/Documentation/hwmon/mp2985.rst b/Documentation/hwmon/mp2985.rst
new file mode 100644
index 000000000000..892c5b5ca19c
--- /dev/null
+++ b/Documentation/hwmon/mp2985.rst
@@ -0,0 +1,151 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver mp2985
+====================
+
+Supported chips:
+
+  * MPS mp2985
+
+    Prefix: 'mp2985'
+
+  * MPS mp2985
+
+    Prefix: 'mp2985'
+
+Author:
+
+	Wensheng Wang <wenswang@yeah.net>
+
+Description
+-----------
+
+This driver implements support for Monolithic Power Systems, Inc. (MPS)
+MP2985 Dual Loop Digital Multi-phase Controller.
+
+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_crit**
+
+**in1_crit_alarm**
+
+**in1_lcrit**
+
+**in1_lcrit_alarm**
+
+**in1_max**
+
+**in1_max_alarm**
+
+**in1_min**
+
+**in1_min_alarm**
+
+The driver provides the following attributes for output voltage:
+
+**in2_input**
+
+**in2_label**
+
+**in2_crit**
+
+**in2_crit_alarm**
+
+**in2_lcrit**
+
+**in2_lcrit_alarm**
+
+**in3_input**
+
+**in3_label**
+
+**in3_crit**
+
+**in3_crit_alarm**
+
+**in3_lcrit**
+
+**in3_lcrit_alarm**
+
+The driver provides the following attributes for input current:
+
+**curr1_input**
+
+**curr1_label**
+
+The driver provides the following attributes for output current:
+
+**curr2_input**
+
+**curr2_label**
+
+**curr2_crit**
+
+**curr2_crit_alarm**
+
+**curr2_max**
+
+**curr2_max_alarm**
+
+**curr3_input**
+
+**curr3_label**
+
+**curr3_crit**
+
+**curr3_crit_alarm**
+
+**curr3_max**
+
+**curr3_max_alarm**
+
+The driver provides the following attributes for input power:
+
+**power1_input**
+
+**power1_label**
+
+**power2_input**
+
+**power2_label**
+
+The driver provides the following attributes for output power:
+
+**power3_input**
+
+**power3_label**
+
+**power4_input**
+
+**power4_label**
+
+The driver provides the following attributes for temperature:
+
+**temp1_input**
+
+**temp1_crit**
+
+**temp1_crit_alarm**
+
+**temp1_max**
+
+**temp1_max_alarm**
+
+**temp2_input**
+
+**temp2_crit**
+
+**temp2_crit_alarm**
+
+**temp2_max**
+
+**temp2_max_alarm**
diff --git a/MAINTAINERS b/MAINTAINERS
index 77fdfcb55f06..7b47e31ee7a3 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17922,6 +17922,13 @@ S:	Maintained
 F:	Documentation/hwmon/mp29502.rst
 F:	drivers/hwmon/pmbus/mp29502.c
 
+MPS MP2985 DRIVER
+M:	Wensheng Wang <wenswang@yeah.net>
+L:	linux-hwmon@vger.kernel.org
+S:	Maintained
+F:	Documentation/hwmon/mp2985.rst
+F:	drivers/hwmon/pmbus/mp2985.c
+
 MPS MP2993 DRIVER
 M:	Noah Wang <noahwang.wang@outlook.com>
 L:	linux-hwmon@vger.kernel.org
diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
index fc1273abe357..83fe5866c083 100644
--- a/drivers/hwmon/pmbus/Kconfig
+++ b/drivers/hwmon/pmbus/Kconfig
@@ -447,6 +447,15 @@ config SENSORS_MP2975
 	  This driver can also be built as a module. If so, the module will
 	  be called mp2975.
 
+config SENSORS_MP2985
+	tristate "MPS MP2985"
+	help
+	  If you say yes here you get hardware monitoring support for MPS
+	  MP2985 Dual Loop Digital Multi-Phase Controller.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called mp2985.
+
 config SENSORS_MP2993
 	tristate "MPS MP2993"
 	help
diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
index d6c86924f887..24505bbee2b0 100644
--- a/drivers/hwmon/pmbus/Makefile
+++ b/drivers/hwmon/pmbus/Makefile
@@ -45,6 +45,7 @@ obj-$(CONFIG_SENSORS_MP2891)	+= mp2891.o
 obj-$(CONFIG_SENSORS_MP2925)	+= mp2925.o
 obj-$(CONFIG_SENSORS_MP29502)	+= mp29502.o
 obj-$(CONFIG_SENSORS_MP2975)	+= mp2975.o
+obj-$(CONFIG_SENSORS_MP2985)	+= mp2985.o
 obj-$(CONFIG_SENSORS_MP2993)	+= mp2993.o
 obj-$(CONFIG_SENSORS_MP5023)	+= mp5023.o
 obj-$(CONFIG_SENSORS_MP5920)	+= mp5920.o
diff --git a/drivers/hwmon/pmbus/mp2985.c b/drivers/hwmon/pmbus/mp2985.c
new file mode 100644
index 000000000000..b96c1096d294
--- /dev/null
+++ b/drivers/hwmon/pmbus/mp2985.c
@@ -0,0 +1,355 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Hardware monitoring driver for MPS Multi-phase Digital VR Controllers(MP2985)
+ *
+ * Copyright (C) 2026 MPS
+ */
+
+#include <linux/bitfield.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include "pmbus.h"
+
+/*
+ * Vender specific register READ_PIN_EST(0x93), READ_IIN_EST(0x8E),
+ * MFR_VR_MULTI_CONFIG_R1(0x0D) and MFR_VR_MULTI_CONFIG_R2(0x1D).
+ * The READ_PIN_EST is used to read pin telemetry, the READ_IIN_EST
+ * is used to read iin telemetry and the MFR_VR_MULTI_CONFIG_R1,
+ * MFR_VR_MULTI_CONFIG_R2 are used to obtain vid scale.
+ */
+#define READ_PIN_EST	0x93
+#define READ_IIN_EST	0x8E
+#define MFR_VR_MULTI_CONFIG_R1	0x0D
+#define MFR_VR_MULTI_CONFIG_R2	0x1D
+
+#define MP2985_VOUT_DIV	512
+#define MP2985_VOUT_OVUV_UINT	195
+#define MP2985_VOUT_OVUV_DIV	100
+
+#define MP2985_PAGE_NUM	2
+
+#define MP2985_RAIL1_FUNC	(PMBUS_HAVE_VIN | PMBUS_HAVE_PIN | \
+							 PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT | \
+							 PMBUS_HAVE_POUT | PMBUS_HAVE_TEMP | \
+							 PMBUS_HAVE_STATUS_VOUT | \
+							 PMBUS_HAVE_STATUS_IOUT | \
+							 PMBUS_HAVE_STATUS_TEMP | \
+							 PMBUS_HAVE_STATUS_INPUT)
+
+#define MP2985_RAIL2_FUNC	(PMBUS_HAVE_PIN | PMBUS_HAVE_VOUT | \
+							 PMBUS_HAVE_IOUT | PMBUS_HAVE_POUT | \
+							 PMBUS_HAVE_TEMP | PMBUS_HAVE_IIN | \
+							 PMBUS_HAVE_STATUS_VOUT | \
+							 PMBUS_HAVE_STATUS_IOUT | \
+							 PMBUS_HAVE_STATUS_TEMP | \
+							 PMBUS_HAVE_STATUS_INPUT)
+
+struct mp2985_data {
+	struct pmbus_driver_info info;
+	int vout_scale[MP2985_PAGE_NUM];
+	int vid_offset[MP2985_PAGE_NUM];
+};
+
+#define to_mp2985_data(x) container_of(x, struct mp2985_data, info)
+
+static u16 mp2985_linear_exp_transfer(u16 word, u16 expect_exponent)
+{
+	s16 exponent, mantissa, target_exponent;
+
+	exponent = ((s16)word) >> 11;
+	mantissa = ((s16)((word & 0x7ff) << 5)) >> 5;
+	target_exponent = (s16)((expect_exponent & 0x1f) << 11) >> 11;
+
+	if (exponent > target_exponent)
+		mantissa = mantissa << (exponent - target_exponent);
+	else
+		mantissa = mantissa >> (target_exponent - exponent);
+
+	return (mantissa & 0x7ff) | ((expect_exponent << 11) & 0xf800);
+}
+
+static int mp2985_read_byte_data(struct i2c_client *client, int page, int reg)
+{
+	int ret;
+
+	switch (reg) {
+	case PMBUS_VOUT_MODE:
+		/*
+		 * The MP2985 does not follow standard PMBus protocol completely,
+		 * and the calculation of vout in this driver is based on direct
+		 * format. As a result, the format of vout is enforced to direct.
+		 */
+		ret = PB_VOUT_MODE_DIRECT;
+		break;
+	default:
+		ret = -ENODATA;
+		break;
+	}
+
+	return ret;
+}
+
+static int mp2985_read_word_data(struct i2c_client *client, int page, int phase,
+				 int reg)
+{
+	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
+	struct mp2985_data *data = to_mp2985_data(info);
+	int ret;
+
+	switch (reg) {
+	case PMBUS_READ_VOUT:
+		ret = pmbus_read_word_data(client, page, phase, reg);
+		if (ret < 0)
+			return ret;
+
+		/*
+		 * In vid mode, the MP2985 vout telemetry has 49 vid step offset, but
+		 * PMBUS_VOUT_OV_FAULT_LIMIT and PMBUS_VOUT_UV_FAULT_LIMIT do not take
+		 * this into consideration, its resolution is 1.95mV/LSB, as a result,
+		 * format[PSC_VOLTAGE_OUT] can not be set to vid directly. Adding extra
+		 * vid_offset variable for vout telemetry.
+		 */
+		ret = DIV_ROUND_CLOSEST(((ret & GENMASK(11, 0)) + data->vid_offset[page]) *
+					data->vout_scale[page], MP2985_VOUT_DIV);
+		break;
+	case PMBUS_READ_IIN:
+		/*
+		 * The MP2985 has standard PMBUS_READ_IIN register(0x89), but this is
+		 * not used to read the input current of per rail. The input current
+		 * is read through the vender redefined register READ_IIN_EST(0x8E).
+		 */
+		ret = pmbus_read_word_data(client, page, phase, READ_IIN_EST);
+		break;
+	case PMBUS_READ_PIN:
+		/*
+		 * The MP2985 has standard PMBUS_READ_PIN register(0x97), but this
+		 * is not used to read the input power of per rail. The input power
+		 * of per rail is read through the vender redefined register
+		 * READ_PIN_EST(0x93).
+		 */
+		ret = pmbus_read_word_data(client, page, phase, READ_PIN_EST);
+		break;
+	case PMBUS_VOUT_OV_FAULT_LIMIT:
+	case PMBUS_VOUT_UV_FAULT_LIMIT:
+		ret = pmbus_read_word_data(client, page, phase, reg);
+		if (ret < 0)
+			return ret;
+
+		ret = DIV_ROUND_CLOSEST((ret & GENMASK(11, 0)) * MP2985_VOUT_OVUV_UINT,
+					MP2985_VOUT_OVUV_DIV);
+		break;
+	case PMBUS_STATUS_WORD:
+	case PMBUS_READ_VIN:
+	case PMBUS_READ_IOUT:
+	case PMBUS_READ_POUT:
+	case PMBUS_READ_TEMPERATURE_1:
+	case PMBUS_VIN_OV_FAULT_LIMIT:
+	case PMBUS_VIN_OV_WARN_LIMIT:
+	case PMBUS_VIN_UV_WARN_LIMIT:
+	case PMBUS_VIN_UV_FAULT_LIMIT:
+	case PMBUS_IOUT_OC_FAULT_LIMIT:
+	case PMBUS_IOUT_OC_WARN_LIMIT:
+	case PMBUS_OT_FAULT_LIMIT:
+	case PMBUS_OT_WARN_LIMIT:
+		ret = -ENODATA;
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	return ret;
+}
+
+static int mp2985_write_word_data(struct i2c_client *client, int page, int reg,
+				  u16 word)
+{
+	int ret;
+
+	switch (reg) {
+	case PMBUS_VIN_OV_FAULT_LIMIT:
+	case PMBUS_VIN_OV_WARN_LIMIT:
+	case PMBUS_VIN_UV_WARN_LIMIT:
+	case PMBUS_VIN_UV_FAULT_LIMIT:
+		/*
+		 * The PMBUS_VIN_OV_FAULT_LIMIT, PMBUS_VIN_OV_WARN_LIMIT,
+		 * PMBUS_VIN_UV_WARN_LIMIT and PMBUS_VIN_UV_FAULT_LIMIT
+		 * of MP2985 is linear11 format, and the exponent is a
+		 * constant value(5'b11101)， so the exponent of word
+		 * parameter should be converted to 5'b11101(0x1D).
+		 */
+		ret = pmbus_write_word_data(client, page, reg,
+					    mp2985_linear_exp_transfer(word, 0x1D));
+		break;
+	case PMBUS_VOUT_OV_FAULT_LIMIT:
+	case PMBUS_VOUT_UV_FAULT_LIMIT:
+		/*
+		 * The bit0-bit11 is the limit value, and bit12-bit15
+		 * should not be changed.
+		 */
+		ret = pmbus_read_word_data(client, page, 0xff, reg);
+		if (ret < 0)
+			return ret;
+
+		ret = pmbus_write_word_data(client, page, reg,
+					    (ret & ~GENMASK(11, 0)) |
+				FIELD_PREP(GENMASK(11, 0),
+					   DIV_ROUND_CLOSEST(word * MP2985_VOUT_OVUV_DIV,
+							     MP2985_VOUT_OVUV_UINT)));
+		break;
+	case PMBUS_OT_FAULT_LIMIT:
+	case PMBUS_OT_WARN_LIMIT:
+		/*
+		 * The PMBUS_OT_FAULT_LIMIT and PMBUS_OT_WARN_LIMIT of
+		 * MP2985 is linear11 format, and the exponent is a
+		 * constant value(5'b00000), so the exponent of word
+		 * parameter should be converted to 5'b00000.
+		 */
+		ret = pmbus_write_word_data(client, page, reg,
+					    mp2985_linear_exp_transfer(word, 0x00));
+		break;
+	case PMBUS_IOUT_OC_FAULT_LIMIT:
+	case PMBUS_IOUT_OC_WARN_LIMIT:
+		/*
+		 * The PMBUS_IOUT_OC_FAULT_LIMIT and PMBUS_IOUT_OC_WARN_LIMIT
+		 * of MP2985 is linear11 format, and the exponent can not be
+		 * changed.
+		 */
+		ret = pmbus_read_word_data(client, page, 0xff, reg);
+		if (ret < 0)
+			return ret;
+
+		ret = pmbus_write_word_data(client, page, reg,
+					    mp2985_linear_exp_transfer(word,
+								       FIELD_GET(GENMASK(15, 11),
+										 ret)));
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	return ret;
+}
+
+static int
+mp2985_identify_vout_scale(struct i2c_client *client, struct pmbus_driver_info *info,
+			   int page)
+{
+	struct mp2985_data *data = to_mp2985_data(info);
+	int ret;
+
+	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, page);
+	if (ret < 0)
+		return ret;
+
+	ret = i2c_smbus_read_byte_data(client, PMBUS_VOUT_MODE);
+	if (ret < 0)
+		return ret;
+
+	if (FIELD_GET(GENMASK(5, 5), ret)) {
+		ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 2);
+		if (ret < 0)
+			return ret;
+
+		ret = i2c_smbus_read_word_data(client, page == 0 ?
+									MFR_VR_MULTI_CONFIG_R1 :
+									MFR_VR_MULTI_CONFIG_R2);
+
+		if (page == 0) {
+			if (FIELD_GET(GENMASK(4, 4), ret))
+				data->vout_scale[page] = 2560;
+			else
+				data->vout_scale[page] = 5120;
+		} else {
+			if (FIELD_GET(GENMASK(3, 3), ret))
+				data->vout_scale[page] = 2560;
+			else
+				data->vout_scale[page] = 5120;
+		}
+
+		data->vid_offset[page] = 49;
+	} else if (FIELD_GET(GENMASK(4, 4), ret)) {
+		data->vout_scale[page] = 1;
+		data->vid_offset[page] = 0;
+	} else {
+		data->vout_scale[page] = 512;
+		data->vid_offset[page] = 0;
+	}
+
+	return 0;
+}
+
+static int mp2985_identify(struct i2c_client *client, struct pmbus_driver_info *info)
+{
+	int ret;
+
+	ret = mp2985_identify_vout_scale(client, info, 0);
+	if (ret < 0)
+		return ret;
+
+	return mp2985_identify_vout_scale(client, info, 1);
+}
+
+static struct pmbus_driver_info mp2985_info = {
+	.pages = MP2985_PAGE_NUM,
+	.format[PSC_VOLTAGE_IN] = linear,
+	.format[PSC_CURRENT_IN] = linear,
+	.format[PSC_CURRENT_OUT] = linear,
+	.format[PSC_POWER] = linear,
+	.format[PSC_TEMPERATURE] = linear,
+	.format[PSC_VOLTAGE_OUT] = direct,
+
+	.m[PSC_VOLTAGE_OUT] = 1,
+	.R[PSC_VOLTAGE_OUT] = 3,
+	.b[PSC_VOLTAGE_OUT] = 0,
+
+	.func[0] = MP2985_RAIL1_FUNC,
+	.func[1] = MP2985_RAIL2_FUNC,
+	.read_word_data = mp2985_read_word_data,
+	.read_byte_data = mp2985_read_byte_data,
+	.write_word_data = mp2985_write_word_data,
+	.identify = mp2985_identify,
+};
+
+static int mp2985_probe(struct i2c_client *client)
+{
+	struct mp2985_data *data;
+
+	data = devm_kzalloc(&client->dev, sizeof(struct mp2985_data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	memcpy(&data->info, &mp2985_info, sizeof(mp2985_info));
+
+	return pmbus_do_probe(client, &data->info);
+}
+
+static const struct i2c_device_id mp2985_id[] = {
+	{"mp2985", 0},
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, mp2985_id);
+
+static const struct of_device_id __maybe_unused mp2985_of_match[] = {
+	{.compatible = "mps,mp2985"},
+	{}
+};
+MODULE_DEVICE_TABLE(of, mp2985_of_match);
+
+static struct i2c_driver mp2985_driver = {
+	.driver = {
+		.name = "mp2985",
+		.of_match_table = mp2985_of_match,
+	},
+	.probe = mp2985_probe,
+	.id_table = mp2985_id,
+};
+
+module_i2c_driver(mp2985_driver);
+
+MODULE_AUTHOR("Wensheng Wang <wenswang@yeah.net>");
+MODULE_DESCRIPTION("PMBus driver for MPS MP2985 device");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("PMBUS");
-- 
2.25.1

Re: [PATCH 2/2] hwmon: add MP2985 driver

[Guenter Roeck]

On Mon, Mar 09, 2026 at 05:02:15PM +0800, wenswang@yeah.net wrote:
> From: Wensheng Wang <wenswang@yeah.net>
> 
> Add support for MPS mp2985 controller. This driver exposes
> telemetry and limit value readings and writtings.
> 
> Signed-off-by: Wensheng Wang <wenswang@yeah.net>
> ---
>  Documentation/hwmon/index.rst  |   1 +
>  Documentation/hwmon/mp2985.rst | 151 ++++++++++++++
>  MAINTAINERS                    |   7 +
>  drivers/hwmon/pmbus/Kconfig    |   9 +
>  drivers/hwmon/pmbus/Makefile   |   1 +
>  drivers/hwmon/pmbus/mp2985.c   | 355 +++++++++++++++++++++++++++++++++
>  6 files changed, 524 insertions(+)
>  create mode 100644 Documentation/hwmon/mp2985.rst
>  create mode 100644 drivers/hwmon/pmbus/mp2985.c
> 
> diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
> index b2ca8513cfcd..1b7007f41b39 100644
> --- a/Documentation/hwmon/index.rst
> +++ b/Documentation/hwmon/index.rst
> @@ -183,6 +183,7 @@ Hardware Monitoring Kernel Drivers
>     mp2925
>     mp29502
>     mp2975
> +   mp2985
>     mp2993
>     mp5023
>     mp5920
> diff --git a/Documentation/hwmon/mp2985.rst b/Documentation/hwmon/mp2985.rst
> new file mode 100644
> index 000000000000..892c5b5ca19c
> --- /dev/null
> +++ b/Documentation/hwmon/mp2985.rst
> @@ -0,0 +1,151 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +Kernel driver mp2985
> +====================
> +
> +Supported chips:
> +
> +  * MPS mp2985
> +
> +    Prefix: 'mp2985'
> +
> +  * MPS mp2985
> +
> +    Prefix: 'mp2985'
> +

Duplicate entry

> +Author:
> +
> +	Wensheng Wang <wenswang@yeah.net>
> +
> +Description
> +-----------
> +
> +This driver implements support for Monolithic Power Systems, Inc. (MPS)
> +MP2985 Dual Loop Digital Multi-phase Controller.
> +
> +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_crit**
> +
> +**in1_crit_alarm**
> +
> +**in1_lcrit**
> +
> +**in1_lcrit_alarm**
> +
> +**in1_max**
> +
> +**in1_max_alarm**
> +
> +**in1_min**
> +
> +**in1_min_alarm**
> +
> +The driver provides the following attributes for output voltage:
> +
> +**in2_input**
> +
> +**in2_label**
> +
> +**in2_crit**
> +
> +**in2_crit_alarm**
> +
> +**in2_lcrit**
> +
> +**in2_lcrit_alarm**
> +
> +**in3_input**
> +
> +**in3_label**
> +
> +**in3_crit**
> +
> +**in3_crit_alarm**
> +
> +**in3_lcrit**
> +
> +**in3_lcrit_alarm**
> +
> +The driver provides the following attributes for input current:
> +
> +**curr1_input**
> +
> +**curr1_label**
> +
> +The driver provides the following attributes for output current:
> +
> +**curr2_input**
> +
> +**curr2_label**
> +
> +**curr2_crit**
> +
> +**curr2_crit_alarm**
> +
> +**curr2_max**
> +
> +**curr2_max_alarm**
> +
> +**curr3_input**
> +
> +**curr3_label**
> +
> +**curr3_crit**
> +
> +**curr3_crit_alarm**
> +
> +**curr3_max**
> +
> +**curr3_max_alarm**
> +
> +The driver provides the following attributes for input power:
> +
> +**power1_input**
> +
> +**power1_label**
> +
> +**power2_input**
> +
> +**power2_label**
> +
> +The driver provides the following attributes for output power:
> +
> +**power3_input**
> +
> +**power3_label**
> +
> +**power4_input**
> +
> +**power4_label**
> +
> +The driver provides the following attributes for temperature:
> +
> +**temp1_input**
> +
> +**temp1_crit**
> +
> +**temp1_crit_alarm**
> +
> +**temp1_max**
> +
> +**temp1_max_alarm**
> +
> +**temp2_input**
> +
> +**temp2_crit**
> +
> +**temp2_crit_alarm**
> +
> +**temp2_max**
> +
> +**temp2_max_alarm**
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 77fdfcb55f06..7b47e31ee7a3 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -17922,6 +17922,13 @@ S:	Maintained
>  F:	Documentation/hwmon/mp29502.rst
>  F:	drivers/hwmon/pmbus/mp29502.c
>  
> +MPS MP2985 DRIVER
> +M:	Wensheng Wang <wenswang@yeah.net>
> +L:	linux-hwmon@vger.kernel.org
> +S:	Maintained
> +F:	Documentation/hwmon/mp2985.rst
> +F:	drivers/hwmon/pmbus/mp2985.c
> +
>  MPS MP2993 DRIVER
>  M:	Noah Wang <noahwang.wang@outlook.com>
>  L:	linux-hwmon@vger.kernel.org
> diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
> index fc1273abe357..83fe5866c083 100644
> --- a/drivers/hwmon/pmbus/Kconfig
> +++ b/drivers/hwmon/pmbus/Kconfig
> @@ -447,6 +447,15 @@ config SENSORS_MP2975
>  	  This driver can also be built as a module. If so, the module will
>  	  be called mp2975.
>  
> +config SENSORS_MP2985
> +	tristate "MPS MP2985"
> +	help
> +	  If you say yes here you get hardware monitoring support for MPS
> +	  MP2985 Dual Loop Digital Multi-Phase Controller.
> +
> +	  This driver can also be built as a module. If so, the module will
> +	  be called mp2985.
> +
>  config SENSORS_MP2993
>  	tristate "MPS MP2993"
>  	help
> diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
> index d6c86924f887..24505bbee2b0 100644
> --- a/drivers/hwmon/pmbus/Makefile
> +++ b/drivers/hwmon/pmbus/Makefile
> @@ -45,6 +45,7 @@ obj-$(CONFIG_SENSORS_MP2891)	+= mp2891.o
>  obj-$(CONFIG_SENSORS_MP2925)	+= mp2925.o
>  obj-$(CONFIG_SENSORS_MP29502)	+= mp29502.o
>  obj-$(CONFIG_SENSORS_MP2975)	+= mp2975.o
> +obj-$(CONFIG_SENSORS_MP2985)	+= mp2985.o
>  obj-$(CONFIG_SENSORS_MP2993)	+= mp2993.o
>  obj-$(CONFIG_SENSORS_MP5023)	+= mp5023.o
>  obj-$(CONFIG_SENSORS_MP5920)	+= mp5920.o
> diff --git a/drivers/hwmon/pmbus/mp2985.c b/drivers/hwmon/pmbus/mp2985.c
> new file mode 100644
> index 000000000000..b96c1096d294
> --- /dev/null
> +++ b/drivers/hwmon/pmbus/mp2985.c
> @@ -0,0 +1,355 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Hardware monitoring driver for MPS Multi-phase Digital VR Controllers(MP2985)
> + *
> + * Copyright (C) 2026 MPS
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include "pmbus.h"
> +
> +/*
> + * Vender specific register READ_PIN_EST(0x93), READ_IIN_EST(0x8E),
> + * MFR_VR_MULTI_CONFIG_R1(0x0D) and MFR_VR_MULTI_CONFIG_R2(0x1D).
> + * The READ_PIN_EST is used to read pin telemetry, the READ_IIN_EST
> + * is used to read iin telemetry and the MFR_VR_MULTI_CONFIG_R1,
> + * MFR_VR_MULTI_CONFIG_R2 are used to obtain vid scale.
> + */
> +#define READ_PIN_EST	0x93
> +#define READ_IIN_EST	0x8E
> +#define MFR_VR_MULTI_CONFIG_R1	0x0D
> +#define MFR_VR_MULTI_CONFIG_R2	0x1D
> +
> +#define MP2985_VOUT_DIV	512
> +#define MP2985_VOUT_OVUV_UINT	195
> +#define MP2985_VOUT_OVUV_DIV	100
> +
> +#define MP2985_PAGE_NUM	2
> +
> +#define MP2985_RAIL1_FUNC	(PMBUS_HAVE_VIN | PMBUS_HAVE_PIN | \
> +							 PMBUS_HAVE_VOUT | PMBUS_HAVE_IOUT | \
> +							 PMBUS_HAVE_POUT | PMBUS_HAVE_TEMP | \
> +							 PMBUS_HAVE_STATUS_VOUT | \
> +							 PMBUS_HAVE_STATUS_IOUT | \
> +							 PMBUS_HAVE_STATUS_TEMP | \
> +							 PMBUS_HAVE_STATUS_INPUT)
> +
> +#define MP2985_RAIL2_FUNC	(PMBUS_HAVE_PIN | PMBUS_HAVE_VOUT | \
> +							 PMBUS_HAVE_IOUT | PMBUS_HAVE_POUT | \
> +							 PMBUS_HAVE_TEMP | PMBUS_HAVE_IIN | \
> +							 PMBUS_HAVE_STATUS_VOUT | \
> +							 PMBUS_HAVE_STATUS_IOUT | \
> +							 PMBUS_HAVE_STATUS_TEMP | \
> +							 PMBUS_HAVE_STATUS_INPUT)
> +
> +struct mp2985_data {
> +	struct pmbus_driver_info info;
> +	int vout_scale[MP2985_PAGE_NUM];
> +	int vid_offset[MP2985_PAGE_NUM];
> +};
> +
> +#define to_mp2985_data(x) container_of(x, struct mp2985_data, info)
> +
> +static u16 mp2985_linear_exp_transfer(u16 word, u16 expect_exponent)
> +{
> +	s16 exponent, mantissa, target_exponent;
> +
> +	exponent = ((s16)word) >> 11;
> +	mantissa = ((s16)((word & 0x7ff) << 5)) >> 5;
> +	target_exponent = (s16)((expect_exponent & 0x1f) << 11) >> 11;
> +
> +	if (exponent > target_exponent)
> +		mantissa = mantissa << (exponent - target_exponent);
> +	else
> +		mantissa = mantissa >> (target_exponent - exponent);
> +
> +	return (mantissa & 0x7ff) | ((expect_exponent << 11) & 0xf800);
> +}
> +
> +static int mp2985_read_byte_data(struct i2c_client *client, int page, int reg)
> +{
> +	int ret;
> +
> +	switch (reg) {
> +	case PMBUS_VOUT_MODE:
> +		/*
> +		 * The MP2985 does not follow standard PMBus protocol completely,
> +		 * and the calculation of vout in this driver is based on direct
> +		 * format. As a result, the format of vout is enforced to direct.
> +		 */
> +		ret = PB_VOUT_MODE_DIRECT;
> +		break;
> +	default:
> +		ret = -ENODATA;
> +		break;
> +	}
> +
> +	return ret;
> +}
> +
> +static int mp2985_read_word_data(struct i2c_client *client, int page, int phase,
> +				 int reg)
> +{
> +	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
> +	struct mp2985_data *data = to_mp2985_data(info);
> +	int ret;
> +
> +	switch (reg) {
> +	case PMBUS_READ_VOUT:
> +		ret = pmbus_read_word_data(client, page, phase, reg);
> +		if (ret < 0)
> +			return ret;
> +
> +		/*
> +		 * In vid mode, the MP2985 vout telemetry has 49 vid step offset, but
> +		 * PMBUS_VOUT_OV_FAULT_LIMIT and PMBUS_VOUT_UV_FAULT_LIMIT do not take
> +		 * this into consideration, its resolution is 1.95mV/LSB, as a result,
> +		 * format[PSC_VOLTAGE_OUT] can not be set to vid directly. Adding extra
> +		 * vid_offset variable for vout telemetry.
> +		 */

This is a bit misleading, since the code (appears to) cover both VID and
non-VID mode. The complete set of supported modes needs to be explained
somewhere.

> +		ret = DIV_ROUND_CLOSEST(((ret & GENMASK(11, 0)) + data->vid_offset[page]) *
> +					data->vout_scale[page], MP2985_VOUT_DIV);

Based on the code below, vout_scale can be 5,120, and vid_offset can be 49.
That means the maximum value of "ret" can be
	(4,095 + 49) * 5,120 / 512, or 41,440

If the result exceeds 32,767, the calling code will interpret this as
negative value. It should be clamped to 32,767 to ensure that this does
not happen.

> +		break;
> +	case PMBUS_READ_IIN:
> +		/*
> +		 * The MP2985 has standard PMBUS_READ_IIN register(0x89), but this is
> +		 * not used to read the input current of per rail. The input current
> +		 * is read through the vender redefined register READ_IIN_EST(0x8E).
> +		 */
> +		ret = pmbus_read_word_data(client, page, phase, READ_IIN_EST);
> +		break;
> +	case PMBUS_READ_PIN:
> +		/*
> +		 * The MP2985 has standard PMBUS_READ_PIN register(0x97), but this
> +		 * is not used to read the input power of per rail. The input power
> +		 * of per rail is read through the vender redefined register
> +		 * READ_PIN_EST(0x93).
> +		 */
> +		ret = pmbus_read_word_data(client, page, phase, READ_PIN_EST);
> +		break;
> +	case PMBUS_VOUT_OV_FAULT_LIMIT:
> +	case PMBUS_VOUT_UV_FAULT_LIMIT:
> +		ret = pmbus_read_word_data(client, page, phase, reg);
> +		if (ret < 0)
> +			return ret;
> +
> +		ret = DIV_ROUND_CLOSEST((ret & GENMASK(11, 0)) * MP2985_VOUT_OVUV_UINT,
> +					MP2985_VOUT_OVUV_DIV);
> +		break;
> +	case PMBUS_STATUS_WORD:
> +	case PMBUS_READ_VIN:
> +	case PMBUS_READ_IOUT:
> +	case PMBUS_READ_POUT:
> +	case PMBUS_READ_TEMPERATURE_1:
> +	case PMBUS_VIN_OV_FAULT_LIMIT:
> +	case PMBUS_VIN_OV_WARN_LIMIT:
> +	case PMBUS_VIN_UV_WARN_LIMIT:
> +	case PMBUS_VIN_UV_FAULT_LIMIT:
> +	case PMBUS_IOUT_OC_FAULT_LIMIT:
> +	case PMBUS_IOUT_OC_WARN_LIMIT:
> +	case PMBUS_OT_FAULT_LIMIT:
> +	case PMBUS_OT_WARN_LIMIT:
> +		ret = -ENODATA;
> +		break;
> +	default:
> +		ret = -EINVAL;
> +		break;
> +	}
> +
> +	return ret;
> +}
> +
> +static int mp2985_write_word_data(struct i2c_client *client, int page, int reg,
> +				  u16 word)
> +{
> +	int ret;
> +
> +	switch (reg) {
> +	case PMBUS_VIN_OV_FAULT_LIMIT:
> +	case PMBUS_VIN_OV_WARN_LIMIT:
> +	case PMBUS_VIN_UV_WARN_LIMIT:
> +	case PMBUS_VIN_UV_FAULT_LIMIT:
> +		/*
> +		 * The PMBUS_VIN_OV_FAULT_LIMIT, PMBUS_VIN_OV_WARN_LIMIT,
> +		 * PMBUS_VIN_UV_WARN_LIMIT and PMBUS_VIN_UV_FAULT_LIMIT
> +		 * of MP2985 is linear11 format, and the exponent is a
> +		 * constant value(5'b11101)， so the exponent of word
> +		 * parameter should be converted to 5'b11101(0x1D).
> +		 */
> +		ret = pmbus_write_word_data(client, page, reg,
> +					    mp2985_linear_exp_transfer(word, 0x1D));
> +		break;
> +	case PMBUS_VOUT_OV_FAULT_LIMIT:
> +	case PMBUS_VOUT_UV_FAULT_LIMIT:
> +		/*
> +		 * The bit0-bit11 is the limit value, and bit12-bit15
> +		 * should not be changed.
> +		 */
> +		ret = pmbus_read_word_data(client, page, 0xff, reg);
> +		if (ret < 0)
> +			return ret;
> +
> +		ret = pmbus_write_word_data(client, page, reg,
> +					    (ret & ~GENMASK(11, 0)) |
> +				FIELD_PREP(GENMASK(11, 0),
> +					   DIV_ROUND_CLOSEST(word * MP2985_VOUT_OVUV_DIV,
> +							     MP2985_VOUT_OVUV_UINT)));
> +		break;
> +	case PMBUS_OT_FAULT_LIMIT:
> +	case PMBUS_OT_WARN_LIMIT:
> +		/*
> +		 * The PMBUS_OT_FAULT_LIMIT and PMBUS_OT_WARN_LIMIT of
> +		 * MP2985 is linear11 format, and the exponent is a
> +		 * constant value(5'b00000), so the exponent of word
> +		 * parameter should be converted to 5'b00000.
> +		 */
> +		ret = pmbus_write_word_data(client, page, reg,
> +					    mp2985_linear_exp_transfer(word, 0x00));
> +		break;
> +	case PMBUS_IOUT_OC_FAULT_LIMIT:
> +	case PMBUS_IOUT_OC_WARN_LIMIT:
> +		/*
> +		 * The PMBUS_IOUT_OC_FAULT_LIMIT and PMBUS_IOUT_OC_WARN_LIMIT
> +		 * of MP2985 is linear11 format, and the exponent can not be
> +		 * changed.
> +		 */
> +		ret = pmbus_read_word_data(client, page, 0xff, reg);
> +		if (ret < 0)
> +			return ret;
> +
> +		ret = pmbus_write_word_data(client, page, reg,
> +					    mp2985_linear_exp_transfer(word,
> +								       FIELD_GET(GENMASK(15, 11),
> +										 ret)));
> +		break;
> +	default:
> +		ret = -EINVAL;
> +		break;
> +	}
> +
> +	return ret;
> +}
> +
> +static int
> +mp2985_identify_vout_scale(struct i2c_client *client, struct pmbus_driver_info *info,
> +			   int page)
> +{
> +	struct mp2985_data *data = to_mp2985_data(info);
> +	int ret;
> +
> +	ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, page);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = i2c_smbus_read_byte_data(client, PMBUS_VOUT_MODE);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (FIELD_GET(GENMASK(5, 5), ret)) {

This is just BIT(5), isn't it ? Why the complexity ?

> +		ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 2);
> +		if (ret < 0)
> +			return ret;

This will leave the chip on page 2, which may confuse the PMBus core.

> +
> +		ret = i2c_smbus_read_word_data(client, page == 0 ?
> +									MFR_VR_MULTI_CONFIG_R1 :
> +									MFR_VR_MULTI_CONFIG_R2);

Return value is not checked.

Alignment is completely off here.

> +
> +		if (page == 0) {
> +			if (FIELD_GET(GENMASK(4, 4), ret))

Same here and everywhere else where the same logic is used.

> +				data->vout_scale[page] = 2560;
> +			else
> +				data->vout_scale[page] = 5120;
> +		} else {
> +			if (FIELD_GET(GENMASK(3, 3), ret))
> +				data->vout_scale[page] = 2560;
> +			else
> +				data->vout_scale[page] = 5120;
> +		}
> +
> +		data->vid_offset[page] = 49;
> +	} else if (FIELD_GET(GENMASK(4, 4), ret)) {
> +		data->vout_scale[page] = 1;
> +		data->vid_offset[page] = 0;
> +	} else {
> +		data->vout_scale[page] = 512;
> +		data->vid_offset[page] = 0;
> +	}

The context suggests that bit 5 and bit 4 may refer to different input modes.
There should be a comment explaining what is what.

> +
> +	return 0;
> +}
> +
> +static int mp2985_identify(struct i2c_client *client, struct pmbus_driver_info *info)
> +{
> +	int ret;
> +
> +	ret = mp2985_identify_vout_scale(client, info, 0);
> +	if (ret < 0)
> +		return ret;
> +
> +	return mp2985_identify_vout_scale(client, info, 1);
> +}
> +
> +static struct pmbus_driver_info mp2985_info = {
> +	.pages = MP2985_PAGE_NUM,
> +	.format[PSC_VOLTAGE_IN] = linear,
> +	.format[PSC_CURRENT_IN] = linear,
> +	.format[PSC_CURRENT_OUT] = linear,
> +	.format[PSC_POWER] = linear,
> +	.format[PSC_TEMPERATURE] = linear,
> +	.format[PSC_VOLTAGE_OUT] = direct,
> +
> +	.m[PSC_VOLTAGE_OUT] = 1,
> +	.R[PSC_VOLTAGE_OUT] = 3,
> +	.b[PSC_VOLTAGE_OUT] = 0,
> +
> +	.func[0] = MP2985_RAIL1_FUNC,
> +	.func[1] = MP2985_RAIL2_FUNC,
> +	.read_word_data = mp2985_read_word_data,
> +	.read_byte_data = mp2985_read_byte_data,
> +	.write_word_data = mp2985_write_word_data,
> +	.identify = mp2985_identify,
> +};
> +
> +static int mp2985_probe(struct i2c_client *client)
> +{
> +	struct mp2985_data *data;
> +
> +	data = devm_kzalloc(&client->dev, sizeof(struct mp2985_data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	memcpy(&data->info, &mp2985_info, sizeof(mp2985_info));
> +
> +	return pmbus_do_probe(client, &data->info);
> +}
> +
> +static const struct i2c_device_id mp2985_id[] = {
> +	{"mp2985", 0},
> +	{}
> +};
> +MODULE_DEVICE_TABLE(i2c, mp2985_id);
> +
> +static const struct of_device_id __maybe_unused mp2985_of_match[] = {
> +	{.compatible = "mps,mp2985"},
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, mp2985_of_match);
> +
> +static struct i2c_driver mp2985_driver = {
> +	.driver = {
> +		.name = "mp2985",
> +		.of_match_table = mp2985_of_match,
> +	},
> +	.probe = mp2985_probe,
> +	.id_table = mp2985_id,
> +};
> +
> +module_i2c_driver(mp2985_driver);
> +
> +MODULE_AUTHOR("Wensheng Wang <wenswang@yeah.net>");
> +MODULE_DESCRIPTION("PMBus driver for MPS MP2985 device");
> +MODULE_LICENSE("GPL");
> +MODULE_IMPORT_NS("PMBUS");

Re: [PATCH 1/2] dt-bindings: hwmon: Add MPS mp2985

[Krzysztof Kozlowski]

On Mon, Mar 09, 2026 at 05:02:14PM +0800, wenswang@yeah.net wrote:
> From: Wensheng Wang <wenswang@yeah.net>
> 
> Add support for MPS mp2985 controller.
> 
> Signed-off-by: Wensheng Wang <wenswang@yeah.net>
> ---
>  Documentation/devicetree/bindings/trivial-devices.yaml | 2 ++
>  1 file changed, 2 insertions(+)
> 

Please version your patches correctly. This looks like v2. You also need
to provide changelog under --- or in cover letter. I will ignore further
versions which are just same postings.

Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>

<form letter>
This is an automated instruction, just in case, because many review
tags are being ignored. If you know the process, just skip it entirely
(please do not feel offended by me posting it here - no bad intentions
intended, no patronizing, I just want to avoid wasted efforts). If you
do not know the process, here is a short explanation:

Please add Acked-by/Reviewed-by/Tested-by tags when posting new
versions of patchset, under or above your Signed-off-by tag, unless
patch changed significantly (e.g. new properties added to the DT
bindings). Tag is "received", when provided in a message replied to you
on the mailing list. Tools like b4 can help here ('b4 trailers -u ...').
However, there's no need to repost patches *only* to add the tags. The
upstream maintainer will do that for tags received on the version they
apply.

https://elixir.bootlin.com/linux/v6.15/source/Documentation/process/submitting-patches.rst#L591
</form letter>

Best regards,
Krzysztof