* [PATCH linux dev-6.18 2/2] hwmon: (pmbus) add driver for MPS MP9945
2026-03-19 6:13 [PATCH linux dev-6.18 1/2] dt-bindings: trivial-devices: add mps,mp9945 Cosmo Chou
@ 2026-03-19 6:13 ` Cosmo Chou
2026-03-26 7:17 ` [PATCH linux dev-6.18 1/2] dt-bindings: trivial-devices: add mps,mp9945 Andrew Jeffery
1 sibling, 0 replies; 3+ messages in thread
From: Cosmo Chou @ 2026-03-19 6:13 UTC (permalink / raw)
To: andrew, openbmc; +Cc: chou.cosmo, cosmo.chou
Add support for mp9945 device from Monolithic Power Systems, Inc.
(MPS) vendor. This is a single phase digital step down converter.
Signed-off-by: Cosmo Chou <chou.cosmo@gmail.com>
Link: https://lore.kernel.org/r/20251009205458.396368-2-chou.cosmo@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
Documentation/hwmon/index.rst | 1 +
Documentation/hwmon/mp9945.rst | 117 ++++++++++++++++
MAINTAINERS | 7 +
drivers/hwmon/pmbus/Kconfig | 9 ++
drivers/hwmon/pmbus/Makefile | 1 +
drivers/hwmon/pmbus/mp9945.c | 243 +++++++++++++++++++++++++++++++++
6 files changed, 378 insertions(+)
create mode 100644 Documentation/hwmon/mp9945.rst
create mode 100644 drivers/hwmon/pmbus/mp9945.c
diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index 2be07966fed6..549017d3689d 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -185,6 +185,7 @@ Hardware Monitoring Kernel Drivers
mp5926
mp5990
mp9941
+ mp9945
mpq8785
nct6683
nct6775
diff --git a/Documentation/hwmon/mp9945.rst b/Documentation/hwmon/mp9945.rst
new file mode 100644
index 000000000000..f406f96efcf9
--- /dev/null
+++ b/Documentation/hwmon/mp9945.rst
@@ -0,0 +1,117 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver mp9945
+=====================
+
+Supported chips:
+
+ * MPS mp9945
+
+ Prefix: 'mp9945'
+
+Author:
+
+ Cosmo Chou <chou.cosmo@gmail.com>
+
+Description
+-----------
+
+This driver implements support for Monolithic Power Systems, Inc. (MPS)
+MP9945 Digital Single-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**
+
+**in2_min**
+
+**in2_min_alarm**
+
+The driver provides the following attributes for input current:
+
+**curr1_input**
+
+**curr1_label**
+
+**curr1_max**
+
+**curr1_max_alarm**
+
+The driver provides the following attributes for output current:
+
+**curr2_input**
+
+**curr2_label**
+
+**curr2_crit**
+
+**curr2_crit_alarm**
+
+**curr2_max**
+
+**curr2_max_alarm**
+
+The driver provides the following attributes for input power:
+
+**power1_input**
+
+**power1_label**
+
+The driver provides the following attributes for output power:
+
+**power2_input**
+
+**power2_label**
+
+**power2_max**
+
+**power2_max_alarm**
+
+The driver provides the following attributes for temperature:
+
+**temp1_input**
+
+**temp1_crit**
+
+**temp1_crit_alarm**
+
+**temp1_max**
+
+**temp1_max_alarm**
diff --git a/MAINTAINERS b/MAINTAINERS
index 10b1f6f61afc..ecfe0799256d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -17529,6 +17529,13 @@ S: Maintained
F: Documentation/hwmon/mp9941.rst
F: drivers/hwmon/pmbus/mp9941.c
+MPS MP9945 DRIVER
+M: Cosmo Chou <chou.cosmo@gmail.com>
+L: linux-hwmon@vger.kernel.org
+S: Maintained
+F: Documentation/hwmon/mp9945.rst
+F: drivers/hwmon/pmbus/mp9945.c
+
MR800 AVERMEDIA USB FM RADIO DRIVER
M: Alexey Klimov <alexey.klimov@linaro.org>
L: linux-media@vger.kernel.org
diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
index 6860673bcecf..cae994fb21ab 100644
--- a/drivers/hwmon/pmbus/Kconfig
+++ b/drivers/hwmon/pmbus/Kconfig
@@ -480,6 +480,15 @@ config SENSORS_MP9941
This driver can also be built as a module. If so, the module will
be called mp9941.
+config SENSORS_MP9945
+ tristate "MPS MP9945"
+ help
+ If you say yes here you get hardware monitoring support for MPS
+ MP9945.
+
+ This driver can also be built as a module. If so, the module will
+ be called mp9945.
+
config SENSORS_MPQ7932_REGULATOR
bool "Regulator support for MPQ7932"
depends on SENSORS_MPQ7932 && REGULATOR
diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
index 57f23fb0ab86..bd37eddf16a7 100644
--- a/drivers/hwmon/pmbus/Makefile
+++ b/drivers/hwmon/pmbus/Makefile
@@ -48,6 +48,7 @@ obj-$(CONFIG_SENSORS_MP5920) += mp5920.o
obj-$(CONFIG_SENSORS_MP5926) += mp5926.o
obj-$(CONFIG_SENSORS_MP5990) += mp5990.o
obj-$(CONFIG_SENSORS_MP9941) += mp9941.o
+obj-$(CONFIG_SENSORS_MP9945) += mp9945.o
obj-$(CONFIG_SENSORS_MPQ7932) += mpq7932.o
obj-$(CONFIG_SENSORS_MPQ8785) += mpq8785.o
obj-$(CONFIG_SENSORS_PLI1209BC) += pli1209bc.o
diff --git a/drivers/hwmon/pmbus/mp9945.c b/drivers/hwmon/pmbus/mp9945.c
new file mode 100644
index 000000000000..34822e0de812
--- /dev/null
+++ b/drivers/hwmon/pmbus/mp9945.c
@@ -0,0 +1,243 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Hardware monitoring driver for MPS Single-phase Digital VR Controllers(MP9945)
+ */
+
+#include <linux/bitfield.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include "pmbus.h"
+
+#define MFR_VR_MULTI_CONFIG_R1 0x08
+#define MFR_SVID_CFG_R1 0xBD
+
+/* VOUT_MODE register values */
+#define VOUT_MODE_LINEAR16 0x17
+#define VOUT_MODE_VID 0x21
+#define VOUT_MODE_DIRECT 0x40
+
+#define MP9945_PAGE_NUM 1
+
+#define MP9945_RAIL1_FUNC (PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | \
+ PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT | \
+ PMBUS_HAVE_PIN | PMBUS_HAVE_POUT | \
+ PMBUS_HAVE_TEMP | \
+ PMBUS_HAVE_STATUS_VOUT | \
+ PMBUS_HAVE_STATUS_IOUT | \
+ PMBUS_HAVE_STATUS_TEMP | \
+ PMBUS_HAVE_STATUS_INPUT)
+
+enum mp9945_vout_mode {
+ MP9945_VOUT_MODE_VID,
+ MP9945_VOUT_MODE_DIRECT,
+ MP9945_VOUT_MODE_LINEAR16,
+};
+
+struct mp9945_data {
+ struct pmbus_driver_info info;
+ enum mp9945_vout_mode vout_mode;
+ int vid_resolution;
+ int vid_offset;
+};
+
+#define to_mp9945_data(x) container_of(x, struct mp9945_data, info)
+
+static int mp9945_read_vout(struct i2c_client *client, struct mp9945_data *data)
+{
+ int ret;
+
+ ret = i2c_smbus_read_word_data(client, PMBUS_READ_VOUT);
+ if (ret < 0)
+ return ret;
+
+ ret &= GENMASK(11, 0);
+
+ switch (data->vout_mode) {
+ case MP9945_VOUT_MODE_VID:
+ if (ret > 0)
+ ret = (ret + data->vid_offset) * data->vid_resolution;
+ break;
+ case MP9945_VOUT_MODE_DIRECT:
+ break;
+ case MP9945_VOUT_MODE_LINEAR16:
+ /* LSB: 1000 * 2^-9 (mV) */
+ ret = DIV_ROUND_CLOSEST(ret * 125, 64);
+ break;
+ default:
+ return -ENODEV;
+ }
+
+ return ret;
+}
+
+static int mp9945_read_byte_data(struct i2c_client *client, int page, int reg)
+{
+ int ret;
+
+ ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 0);
+ if (ret < 0)
+ return ret;
+
+ switch (reg) {
+ case PMBUS_VOUT_MODE:
+ /*
+ * Override VOUT_MODE to DIRECT as the driver handles custom
+ * VOUT format conversions internally.
+ */
+ return PB_VOUT_MODE_DIRECT;
+ default:
+ return -ENODATA;
+ }
+}
+
+static int mp9945_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 mp9945_data *data = to_mp9945_data(info);
+ int ret;
+
+ ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 0);
+ if (ret < 0)
+ return ret;
+
+ switch (reg) {
+ case PMBUS_READ_VOUT:
+ ret = mp9945_read_vout(client, data);
+ break;
+ case PMBUS_VOUT_OV_FAULT_LIMIT:
+ case PMBUS_VOUT_UV_FAULT_LIMIT:
+ ret = i2c_smbus_read_word_data(client, reg);
+ if (ret < 0)
+ return ret;
+
+ /* LSB: 1.95 (mV) */
+ ret = DIV_ROUND_CLOSEST((ret & GENMASK(11, 0)) * 39, 20);
+ break;
+ case PMBUS_VOUT_UV_WARN_LIMIT:
+ ret = i2c_smbus_read_word_data(client, reg);
+ if (ret < 0)
+ return ret;
+
+ ret &= GENMASK(9, 0);
+ if (ret > 0)
+ ret = (ret + data->vid_offset) * data->vid_resolution;
+ break;
+ default:
+ ret = -ENODATA;
+ break;
+ }
+
+ return ret;
+}
+
+static int mp9945_identify(struct i2c_client *client,
+ struct pmbus_driver_info *info)
+{
+ struct mp9945_data *data = to_mp9945_data(info);
+ int ret;
+
+ ret = i2c_smbus_read_byte_data(client, PMBUS_VOUT_MODE);
+ if (ret < 0)
+ return ret;
+
+ switch (ret) {
+ case VOUT_MODE_LINEAR16:
+ data->vout_mode = MP9945_VOUT_MODE_LINEAR16;
+ break;
+ case VOUT_MODE_VID:
+ data->vout_mode = MP9945_VOUT_MODE_VID;
+ break;
+ case VOUT_MODE_DIRECT:
+ data->vout_mode = MP9945_VOUT_MODE_DIRECT;
+ break;
+ default:
+ return -ENODEV;
+ }
+
+ ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 3);
+ if (ret < 0)
+ return ret;
+
+ ret = i2c_smbus_read_word_data(client, MFR_VR_MULTI_CONFIG_R1);
+ if (ret < 0)
+ return ret;
+
+ data->vid_resolution = (FIELD_GET(BIT(2), ret)) ? 5 : 10;
+
+ ret = i2c_smbus_read_word_data(client, MFR_SVID_CFG_R1);
+ if (ret < 0)
+ return ret;
+
+ data->vid_offset = (FIELD_GET(BIT(15), ret)) ? 19 : 49;
+
+ return i2c_smbus_write_byte_data(client, PMBUS_PAGE, 0);
+}
+
+static struct pmbus_driver_info mp9945_info = {
+ .pages = MP9945_PAGE_NUM,
+ .format[PSC_VOLTAGE_IN] = linear,
+ .format[PSC_VOLTAGE_OUT] = direct,
+ .format[PSC_CURRENT_IN] = linear,
+ .format[PSC_CURRENT_OUT] = linear,
+ .format[PSC_POWER] = linear,
+ .format[PSC_TEMPERATURE] = linear,
+ .m[PSC_VOLTAGE_OUT] = 1,
+ .R[PSC_VOLTAGE_OUT] = 3,
+ .b[PSC_VOLTAGE_OUT] = 0,
+ .func[0] = MP9945_RAIL1_FUNC,
+ .read_word_data = mp9945_read_word_data,
+ .read_byte_data = mp9945_read_byte_data,
+ .identify = mp9945_identify,
+};
+
+static int mp9945_probe(struct i2c_client *client)
+{
+ struct mp9945_data *data;
+ int ret;
+
+ data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ memcpy(&data->info, &mp9945_info, sizeof(mp9945_info));
+
+ /*
+ * Set page 0 before probe. The core reads paged registers which are
+ * only on page 0 for this device.
+ */
+ ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, 0);
+ if (ret < 0)
+ return ret;
+
+ return pmbus_do_probe(client, &data->info);
+}
+
+static const struct i2c_device_id mp9945_id[] = {
+ {"mp9945"},
+ {}
+};
+MODULE_DEVICE_TABLE(i2c, mp9945_id);
+
+static const struct of_device_id __maybe_unused mp9945_of_match[] = {
+ {.compatible = "mps,mp9945"},
+ {}
+};
+MODULE_DEVICE_TABLE(of, mp9945_of_match);
+
+static struct i2c_driver mp9945_driver = {
+ .driver = {
+ .name = "mp9945",
+ .of_match_table = of_match_ptr(mp9945_of_match),
+ },
+ .probe = mp9945_probe,
+ .id_table = mp9945_id,
+};
+
+module_i2c_driver(mp9945_driver);
+
+MODULE_AUTHOR("Cosmo Chou <chou.cosmo@gmail.com>");
+MODULE_DESCRIPTION("PMBus driver for MPS MP9945");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("PMBUS");
--
2.43.0
^ permalink raw reply related [flat|nested] 3+ messages in thread