* [PATCH v4 2/2] hwmon: add MP2985 driver
2026-04-14 9:29 ` [PATCH v4 1/2] dt-bindings: hwmon: Add " wenswang
@ 2026-04-14 9:29 ` wenswang
0 siblings, 0 replies; 3+ messages in thread
From: wenswang @ 2026-04-14 9:29 UTC (permalink / raw)
To: robh, krzk+dt, conor+dt, linux, corbet, skhan
Cc: devicetree, linux-kernel, linux-hwmon, linux-doc, Wensheng Wang
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>
---
V3 -> V4:
1. Avoid mantissa data overflow in mp2985_linear_exp_transfer()
function.
V2 -> V3:
1. The shifted mantissa be clamped to the range [-1024, 1023]
before being masked in mp2985_linear_exp_transfer() function.
2. The PMBUS_VOUT_OV_FAULT_LIMIT and PMBUS_VOUT_UV_FAULT_LIMIT
value are clamped to 0xFFF before being written to the mp2985.
3. Fix the vout scale issue for vout linear11 mode.
v1 -> v2:
1. remove duplicate entry in mp2985.rst
2. clamp vout value to 32767
3. simplify the code for obtaining PMBUS_VOUT_MODE bit value
4. add comment for explaining MP2985 supported vout mode
5. switch back to previous page after obtaining vid scale to avoid
confusing the PMBus core
Documentation/hwmon/index.rst | 1 +
Documentation/hwmon/mp2985.rst | 147 ++++++++++++
MAINTAINERS | 7 +
drivers/hwmon/pmbus/Kconfig | 9 +
drivers/hwmon/pmbus/Makefile | 1 +
drivers/hwmon/pmbus/mp2985.c | 402 +++++++++++++++++++++++++++++++++
6 files changed, 567 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..87a39c8a300c
--- /dev/null
+++ b/Documentation/hwmon/mp2985.rst
@@ -0,0 +1,147 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver mp2985
+====================
+
+Supported chips:
+
+ * 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 3adc870d523b..ead04c2d1665 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17933,6 +17933,13 @@ 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..eb1a25b00c0b
--- /dev/null
+++ b/drivers/hwmon/pmbus/mp2985.c
@@ -0,0 +1,402 @@
+// 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 64
+#define MP2985_VOUT_OVUV_UINT 125
+#define MP2985_VOUT_OVUV_DIV 64
+
+#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;
+
+ /*
+ * The MP2985 does not support negtive limit value, if a negtive
+ * limit value is written, the limit value will become to 0. And
+ * the maximum positive limit value is limitted to 0x3FF.
+ */
+ if (mantissa < 0) {
+ mantissa = 0;
+ } else {
+ if (exponent > target_exponent) {
+ mantissa = (1023 >> (exponent - target_exponent)) >= mantissa ?
+ mantissa << (exponent - target_exponent) :
+ 0x3FF;
+ } else {
+ mantissa = clamp_val(mantissa >> (target_exponent - exponent),
+ 0, 0x3FF);
+ }
+ }
+
+ return mantissa | ((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;
+
+ /*
+ * The MP2985 supports three vout mode, direct, linear11 and vid mode.
+ * 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, their resolution are 1.953125mV/LSB, as a
+ * result, format[PSC_VOLTAGE_OUT] can not be set to vid mode directly.
+ * Adding extra vid_offset variable for vout telemetry.
+ */
+ ret = clamp_val(DIV_ROUND_CLOSEST(((ret & GENMASK(11, 0)) +
+ data->vid_offset[page]) *
+ data->vout_scale[page], MP2985_VOUT_DIV),
+ 0, 0x7FFF);
+ 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:
+ /*
+ * These register is not explicitly handled by the driver,
+ * as a result, return -ENODATA directly.
+ */
+ ret = -ENODATA;
+ break;
+ default:
+ /*
+ * The MP2985 do not support other telemetry and limit value
+ * reading, so, return -EINVAL directly.
+ */
+ 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)) |
+ clamp_val(DIV_ROUND_CLOSEST(word * MP2985_VOUT_OVUV_DIV,
+ MP2985_VOUT_OVUV_UINT), 0, 0xFFF));
+ 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:
+ /*
+ * The MP2985 do not support other limit value configuration,
+ * so, return -EINVAL directly.
+ */
+ 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;
+
+ /*
+ * The MP2985 supports three vout mode. If PMBUS_VOUT_MODE
+ * bit5 is 1, it is vid mode. If PMBUS PMBUS_VOUT_MODE bit4
+ * is 1, it is linear11 mode, the vout scale is 1.953125mv/LSB.
+ * If PMBUS PMBUS_VOUT_MODE bit6 is 1, it is direct mode, the
+ * vout scale is 1mv/LSB. In vid mode, the MP2985 vout telemetry
+ * has 49 vid step offset.
+ */
+ if (FIELD_GET(BIT(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 (ret < 0)
+ return ret;
+
+ if (page == 0) {
+ if (FIELD_GET(BIT(4), ret))
+ data->vout_scale[page] = 320;
+ else
+ data->vout_scale[page] = 640;
+ } else {
+ if (FIELD_GET(BIT(3), ret))
+ data->vout_scale[page] = 320;
+ else
+ data->vout_scale[page] = 640;
+ }
+
+ data->vid_offset[page] = 49;
+
+ /*
+ * For vid mode, the MP2985 should be changed to page 2
+ * to obtain vout scale value, this may confuse the PMBus
+ * core. To avoid this, switch back to the previous page
+ * again.
+ */
+ ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, page);
+ if (ret < 0)
+ return ret;
+ } else if (FIELD_GET(BIT(4), ret)) {
+ data->vout_scale[page] = 125;
+ data->vid_offset[page] = 0;
+ } else {
+ data->vout_scale[page] = 64;
+ 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
^ permalink raw reply related [flat|nested] 3+ messages in thread