[PATCH v2 0/2] hwmon: (pmbus) Add support for MPS mp2869a/mp29612a controllers

[PATCH v2 0/2] hwmon: (pmbus) Add support for MPS mp2869a/mp29612a controllers

[tzuhao.wtmh]

From: Henry Wu <Henry_Wu@quantatw.com>

Add support for the mp2869a and mp29612a controllers from Monolithic Power
Systems, Inc. (MPS). These are dual-loop, digital, multi-phase modulation
controllers.

---

Changes in v2:
- Fix coding style issues.
- Using the pointer to replace the memcpy.
- Fix wrong device tree entries.

Link to v1: https://lore.kernel.org/lkml/20250624074156.291176-1-Henry_Wu@quantatw.tw/

---

Henry Wu (2):
  hwmon: (pmbus) Add support for MPS multi-phase mp2869a/mp29612a
    controllers
  dt-bindings: trivial-devices: Add mp2869a/mp29612a device entry

 .../devicetree/bindings/trivial-devices.yaml  |   4 +
 Documentation/hwmon/index.rst                 |   1 +
 Documentation/hwmon/mp2869a.rst               |  86 +++++
 drivers/hwmon/pmbus/Kconfig                   |  10 +
 drivers/hwmon/pmbus/Makefile                  |   1 +
 drivers/hwmon/pmbus/mp2869a.c                 | 299 ++++++++++++++++++
 6 files changed, 401 insertions(+)
 create mode 100644 Documentation/hwmon/mp2869a.rst
 create mode 100644 drivers/hwmon/pmbus/mp2869a.c

-- 
2.43.0

[PATCH v2 1/2] hwmon: (pmbus) Add support for MPS multi-phase mp2869a/mp29612a controllers

[tzuhao.wtmh]

From: Henry Wu <Henry_Wu@quantatw.com>

Add support for the mp2869a and mp29612a controllers from Monolithic Power
Systems, Inc. (MPS). These are dual-loop, digital, multi-phase modulation
controllers.

Signed-off-by: Henry Wu <Henry_Wu@quantatw.com>
---
 Documentation/hwmon/index.rst   |   1 +
 Documentation/hwmon/mp2869a.rst |  86 +++++++++
 drivers/hwmon/pmbus/Kconfig     |  10 ++
 drivers/hwmon/pmbus/Makefile    |   1 +
 drivers/hwmon/pmbus/mp2869a.c   | 299 ++++++++++++++++++++++++++++++++
 5 files changed, 397 insertions(+)
 create mode 100644 Documentation/hwmon/mp2869a.rst
 create mode 100644 drivers/hwmon/pmbus/mp2869a.c

diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index b45bfb4ebf30..10bf4bd77f7b 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -172,6 +172,7 @@ Hardware Monitoring Kernel Drivers
    menf21bmc
    mlxreg-fan
    mp2856
+   mp2869a
    mp2888
    mp2891
    mp2975
diff --git a/Documentation/hwmon/mp2869a.rst b/Documentation/hwmon/mp2869a.rst
new file mode 100644
index 000000000000..a98ccb3d630d
--- /dev/null
+++ b/Documentation/hwmon/mp2869a.rst
@@ -0,0 +1,86 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver mp2896a
+=====================
+
+Supported chips:
+
+  * MPS MP2896A
+
+    Prefix: 'mp2896a'
+
+  * MPS MP29612A
+
+    Prefix: 'mp29612a'
+
+Author:
+
+    Henry Wu <Henry_WU@quantatw.com>
+
+Description
+-----------
+
+This driver implements support for Monolithic Power Systems, Inc. (MPS)
+MP2896A, a digital, multi-phase voltage regulator controller with PMBus interface.
+
+This device:
+
+- Supports up to two power rails.
+- Supports multiple PMBus pages for telemetry and configuration.
+- Supports VOUT readout in **VID format only** (no support for direct format).
+- Supports AMD SVI3 VID protocol with 5-mV/LSB resolution (if applicable).
+- Uses vendor-specific registers for VOUT scaling and phase configuration.
+
+Device supports:
+
+- SVID interface.
+- AVSBus interface.
+
+Device compliant with:
+
+- PMBus rev 1.3 interface.
+
+Sysfs Interface
+---------------
+
+The driver provides the following sysfs attributes:
+
+**Current measurements:**
+
+- Index 1: "iin"
+- Indexes 2, 3: "iout"
+
+**curr[1-3]_alarm**
+**curr[1-3]_input**
+**curr[1-3]_label**
+
+**Voltage measurements:**
+
+- Index 1: "vin"
+- Indexes 2, 3: "vout"
+
+**in[1-3]_crit**
+**in[1-3]_crit_alarm**
+**in[1-3]_input**
+**in[1-3]_label**
+**in[1-3]_lcrit**
+**in[1-3]_lcrit_alarm**
+
+**Power measurements:**
+
+- Index 1: "pin"
+- Indexes 2, 3: "pout"
+
+**power[1-3]_alarm**
+**power[1-3]_input**
+**power[1-3]_label**
+
+**Temperature measurements:**
+
+**temp[1-2]_crit**
+**temp[1-2]_crit_alarm**
+**temp[1-2]_input**
+**temp[1-2]_max**
+**temp[1-2]_max_alarm**
+
+
diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
index 441f984a859d..93b558761cc6 100644
--- a/drivers/hwmon/pmbus/Kconfig
+++ b/drivers/hwmon/pmbus/Kconfig
@@ -364,6 +364,16 @@ config SENSORS_MP2856
 	  This driver can also be built as a module. If so, the module will
 	  be called mp2856.
 
+config SENSORS_MP2869A
+	tristate "MP2869A PMBus sensor"
+	depends on I2C && PMBUS
+	help
+	  If you say yes here you get support for the MPS MP2869A MP29612A
+	  voltage regulator via the PMBus interface.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called mp2869a.
+
 config SENSORS_MP2888
 	tristate "MPS MP2888"
 	help
diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
index 29cd8a3317d2..42087d0dedbc 100644
--- a/drivers/hwmon/pmbus/Makefile
+++ b/drivers/hwmon/pmbus/Makefile
@@ -37,6 +37,7 @@ obj-$(CONFIG_SENSORS_MAX31785)	+= max31785.o
 obj-$(CONFIG_SENSORS_MAX34440)	+= max34440.o
 obj-$(CONFIG_SENSORS_MAX8688)	+= max8688.o
 obj-$(CONFIG_SENSORS_MP2856)	+= mp2856.o
+obj-$(CONFIG_SENSORS_MP2869A)   += mp2869a.o
 obj-$(CONFIG_SENSORS_MP2888)	+= mp2888.o
 obj-$(CONFIG_SENSORS_MP2891)	+= mp2891.o
 obj-$(CONFIG_SENSORS_MP2975)	+= mp2975.o
diff --git a/drivers/hwmon/pmbus/mp2869a.c b/drivers/hwmon/pmbus/mp2869a.c
new file mode 100644
index 000000000000..e61f1380dbc1
--- /dev/null
+++ b/drivers/hwmon/pmbus/mp2869a.c
@@ -0,0 +1,299 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Hardware monitoring driver for MP2856A/MP29612A
+ * Monolithic Power Systems VR Controller
+ *
+ * Copyright (C) 2023 Quanta Computer lnc.
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/pmbus.h>
+#include "pmbus.h"
+
+/* Vendor specific registers. */
+#define MP2869A_VOUT_MODE			 0x20
+#define MP2869A_VOUT_MODE_MASK		 GENMASK(7, 5)
+#define MP2869A_VOUT_MODE_VID		 (0 << 5)
+
+#define MP2869A_READ_VOUT			 0x8b
+
+#define MP2869A_MFR_VOUT_SCALE_LOOP	 0x29
+#define MP2869A_VID_RES_MASK		 GENMASK(12, 10)
+#define MP2869A_VOUT_SCALE_MASK		 GENMASK(7, 0)
+
+#define MP2869A_MAX_PHASE_RAIL1		 16
+#define MP2869A_MAX_PHASE_RAIL2		 8
+#define MP29612A_MAX_PHASE_RAIL1	 12
+#define MP29612A_MAX_PHASE_RAIL2	 6
+
+#define MP2869A_PAGE_NUM			 2
+#define MP29612A_PAGE_NUM			 2
+
+#define MP2869A_GAIN_BASE			 32000
+
+enum chips { mp2869a = 1, mp29612a };
+
+static const int mp2869a_max_phases[][MP2869A_PAGE_NUM] = {
+	[mp2869a] = { MP2869A_MAX_PHASE_RAIL1, MP2869A_MAX_PHASE_RAIL2 },
+	[mp29612a] = { MP29612A_MAX_PHASE_RAIL1, MP29612A_MAX_PHASE_RAIL2},
+};
+
+static const struct i2c_device_id mp2869a_id[] = {
+	{ "mp2869a", mp2869a },
+	{ "mp29612a", mp29612a },
+	{}
+};
+
+MODULE_DEVICE_TABLE(i2c, mp2869a_id);
+
+struct mp2869a_data {
+	struct pmbus_driver_info info;
+	int vout_format[MP2869A_PAGE_NUM];
+	int curr_sense_gain[MP2869A_PAGE_NUM];
+	const int *max_phases;
+	enum chips chip_id;
+};
+
+#define to_mp2869a_data(x)	container_of(x, struct mp2869a_data, info)
+
+static int
+mp2869a_read_word_helper(struct i2c_client *client, int page, int phase, u8 reg,
+	u16 mask)
+{
+	int ret = pmbus_read_word_data(client, page, phase, reg);
+
+	return (ret > 0) ? ret & mask : ret;
+}
+
+struct mp2869a_vout_info {
+	int vid_step_uv;
+	int vdiff_gain_ratio;
+};
+
+static int
+mp2869a_read_vid_and_scale(struct i2c_client *client, struct mp2869a_data *data,
+	int page, int phase,
+	struct mp2869a_vout_info *out)
+{
+	int ret;
+	u16 reg_val;
+	u8 vid_sel, vscale;
+
+	ret = pmbus_read_word_data(client, page, phase,
+		MP2869A_MFR_VOUT_SCALE_LOOP);
+	if (ret < 0)
+		return ret;
+
+	reg_val = (u16)ret;
+
+	/* Analyze VID Step Resolution（bits 12:10） */
+	vid_sel = (reg_val >> 10) & 0x7;
+	switch (vid_sel) {
+	case 0b000:
+		out->vid_step_uv = 6250;
+		break;
+	case 0b001:
+		out->vid_step_uv = 5000;
+		break;
+	case 0b010:
+		out->vid_step_uv = 2500;
+		break;
+	case 0b011:
+		out->vid_step_uv = 2000;
+		break;
+	case 0b100:
+		out->vid_step_uv = 1000;
+		break;
+	case 0b101:
+		/* 1000000 / 256 */
+		out->vid_step_uv = 3906;
+		break;
+	case 0b110:
+		/* 1000000 / 512 */
+		out->vid_step_uv = 1953;
+		break;
+	case 0b111:
+		/* 1000000 / 1024 */
+		out->vid_step_uv = 977;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* Analyze VOUT_SCALE_LOOP（bits 7:0） */
+	vscale = reg_val & 0xff;
+	if (vscale == 0)
+		return -EINVAL;
+	/* Store as "magnification * 1000" to avoid floating point */
+	out->vdiff_gain_ratio = MP2869A_GAIN_BASE / vscale;
+
+	return 0;
+}
+
+static int
+mp2869a_read_vout(struct i2c_client *client, struct mp2869a_data *data,
+	int page, int phase, u8 reg)
+{
+	int ret;
+	int raw;
+	struct mp2869a_vout_info vout_info;
+
+	raw = mp2869a_read_word_helper(client, page, phase, reg, GENMASK(11, 0));
+	if (raw < 0)
+		return raw;
+
+	ret = mp2869a_read_vid_and_scale(client, data, page, phase, &vout_info);
+	if (ret < 0)
+		return ret;
+
+	int m = 1;
+	int R = 0;
+	int step = vout_info.vid_step_uv;
+
+	/* Let step = 10^R / m */
+	while (step % 10 == 0 && R > -6) {
+		step /= 10;
+		R--;
+	}
+	/* approximate if step ≠ 1mV, 5mV, etc */
+	m = 1000000 / vout_info.vid_step_uv;
+
+	data->info.m[PSC_VOLTAGE_OUT] = m;
+	data->info.R[PSC_VOLTAGE_OUT] = R+3;
+	data->info.b[PSC_VOLTAGE_OUT] = 0;
+
+	return raw;
+}
+
+static int
+mp2869a_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 mp2869a_data *data = to_mp2869a_data(info);
+	int ret;
+
+	switch (reg) {
+	case PMBUS_READ_VOUT:
+		ret = mp2869a_read_vout(client, data, page, phase, reg);
+		break;
+	default:
+		return -ENODATA;
+	}
+
+	return ret;
+}
+
+static int
+mp2869a_read_byte_data(struct i2c_client *client, int page, int reg)
+{
+	switch (reg) {
+	case PMBUS_VOUT_MODE:
+		/* Enforce VOUT direct format. */
+		return PB_VOUT_MODE_DIRECT;
+	default:
+		return -ENODATA;
+	}
+}
+
+static int
+mp2869a_identify_vout_format(struct i2c_client *client,
+	struct mp2869a_data *data)
+{
+	int i, ret;
+
+	for (i = 0; i < data->info.pages; i++) {
+		ret = i2c_smbus_write_byte_data(client, PMBUS_PAGE, i);
+		if (ret < 0)
+			return ret;
+
+		ret = i2c_smbus_read_word_data(client, MP2869A_VOUT_MODE);
+		if (ret < 0)
+			return ret;
+
+		switch (ret & MP2869A_VOUT_MODE_MASK) {
+		case MP2869A_VOUT_MODE_VID:
+			data->vout_format[i] = vid;
+			break;
+		default:
+			return -EINVAL;
+		}
+	}
+	return 0;
+}
+
+static const struct pmbus_driver_info mp2869a_info = {
+	.pages = MP2869A_PAGE_NUM,
+	.format[PSC_VOLTAGE_IN] = linear,
+	.format[PSC_VOLTAGE_OUT] = direct,
+	.format[PSC_TEMPERATURE] = linear,
+	.format[PSC_CURRENT_IN] = linear,
+	.format[PSC_CURRENT_OUT] = linear,
+	.format[PSC_POWER] = linear,
+	.m[PSC_VOLTAGE_OUT] = 1,
+	.b[PSC_VOLTAGE_OUT] = 0,
+	.R[PSC_VOLTAGE_OUT] = -3,
+	.func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT |
+		PMBUS_HAVE_IIN | PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT |
+		PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP | PMBUS_HAVE_POUT |
+		PMBUS_HAVE_PIN | PMBUS_HAVE_STATUS_INPUT,
+	.func[1] = PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT | PMBUS_HAVE_IOUT |
+		PMBUS_HAVE_STATUS_IOUT | PMBUS_HAVE_POUT | PMBUS_HAVE_TEMP,
+	.read_byte_data = mp2869a_read_byte_data,
+	.read_word_data = mp2869a_read_word_data,
+};
+
+static int mp2869a_probe(struct i2c_client *client)
+{
+	struct pmbus_driver_info *info;
+	struct mp2869a_data *data;
+	int ret;
+
+	data = devm_kzalloc(&client->dev, sizeof(struct mp2869a_data),
+		GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->chip_id = (enum chips)(kernel_ulong_t)i2c_get_match_data(client);
+	data->max_phases = mp2869a_max_phases[data->chip_id];
+	info = &data->info;
+	*info = mp2869a_info;
+
+	/* Identify vout format. */
+	ret = mp2869a_identify_vout_format(client, data);
+	if (ret)
+		return ret;
+
+	/* set the device to page 0 */
+	i2c_smbus_write_byte_data(client, PMBUS_PAGE, 0);
+
+	return pmbus_do_probe(client, info);
+}
+
+static const struct of_device_id __maybe_unused mp2869a_of_match[] = {
+	{ .compatible = "mps,mp2869a", .data = (void *)mp2869a },
+	{ .compatible = "mps,mp29612a", .data = (void *)mp29612a},
+	{}
+};
+
+MODULE_DEVICE_TABLE(of, mp2869a_of_match);
+
+static struct i2c_driver mp2869a_driver = {
+	.driver = {
+		.name = "mp2869a",
+		.of_match_table = mp2869a_of_match,
+	},
+	.probe = mp2869a_probe,
+	.id_table = mp2869a_id,
+};
+
+module_i2c_driver(mp2869a_driver);
+
+MODULE_AUTHOR("Henry Wu <Henry_WU@quantatw.com>");
+MODULE_DESCRIPTION("PMBus driver for MPS MP2869A/MP29612A device");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("PMBUS");
-- 
2.43.0

[PATCH v2 2/2] dt-bindings: trivial-devices: Add mp2869a/mp29612a device entry

[tzuhao.wtmh]

From: Henry Wu <Henry_Wu@quantatw.com>

Add trivial-devices binding for mp2869a/mp29612a to enable automatic matching
in device tree.

Signed-off-by: Henry Wu <Henry_Wu@quantatw.com>
---
 Documentation/devicetree/bindings/trivial-devices.yaml | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Documentation/devicetree/bindings/trivial-devices.yaml b/Documentation/devicetree/bindings/trivial-devices.yaml
index 27930708ccd5..5657fdcabb45 100644
--- a/Documentation/devicetree/bindings/trivial-devices.yaml
+++ b/Documentation/devicetree/bindings/trivial-devices.yaml
@@ -285,10 +285,14 @@ properties:
           - mps,mp2856
             # Monolithic Power Systems Inc. multi-phase controller mp2857
           - mps,mp2857
+            # Monolithic Power Systems Inc. multi-phase controller mp2869a
+          - mps,mp2869a
             # Monolithic Power Systems Inc. multi-phase controller mp2888
           - mps,mp2888
             # Monolithic Power Systems Inc. multi-phase controller mp2891
           - mps,mp2891
+            # Monolithic Power Systems Inc. multi-phase controller mp29612a
+          - mps,mp29612a
             # Monolithic Power Systems Inc. multi-phase controller mp2993
           - mps,mp2993
             # Monolithic Power Systems Inc. multi-phase hot-swap controller mp5920
-- 
2.43.0

Re: [PATCH v2 2/2] dt-bindings: trivial-devices: Add mp2869a/mp29612a device entry

[Krzysztof Kozlowski]

On 30/06/2025 13:20, tzuhao.wtmh@gmail.com wrote:
> From: Henry Wu <Henry_Wu@quantatw.com>
> 
> Add trivial-devices binding for mp2869a/mp29612a to enable automatic matching
> in device tree.

Nothing improved. You did not respond to my comments and just sent the same.

No, implement and respond to comments.


Best regards,
Krzysztof

Re: [PATCH v2 0/2] hwmon: (pmbus) Add support for MPS mp2869a/mp29612a controllers

[Krzysztof Kozlowski]

On 30/06/2025 13:20, tzuhao.wtmh@gmail.com wrote:
> From: Henry Wu <Henry_Wu@quantatw.com>
> 
> Add support for the mp2869a and mp29612a controllers from Monolithic Power
> Systems, Inc. (MPS). These are dual-loop, digital, multi-phase modulation
> controllers.
> 
> ---
> 
> Changes in v2:
> - Fix coding style issues.

Which ones? How?

> - Using the pointer to replace the memcpy.
> - Fix wrong device tree entries.

What exactly? How did you fix it? I see zero changes. Your changelog
should be specific, not vague.


Best regards,
Krzysztof

Re: [PATCH v2 2/2] dt-bindings: trivial-devices: Add mp2869a/mp29612a device entry

[Henry Wu]

Krzysztof Kozlowski <krzk@kernel.org> 於 2025年6月30日 週一 下午7:28寫道：
>
> On 30/06/2025 13:20, tzuhao.wtmh@gmail.com wrote:
> > From: Henry Wu <Henry_Wu@quantatw.com>
> >
> > Add trivial-devices binding for mp2869a/mp29612a to enable automatic matching
> > in device tree.
>
> Nothing improved. You did not respond to my comments and just sent the same.
>
> No, implement and respond to comments.
>
I’m sorry, that was my mistake. I will update the description to:
Add trivial-devices bindings for MP2869A/MP29612A voltage regulator controllers.
>
>
> Best regards,
> Krzysztof

Re: [PATCH v2 0/2] hwmon: (pmbus) Add support for MPS mp2869a/mp29612a controllers

[Henry Wu]

Krzysztof Kozlowski <krzk@kernel.org> 於 2025年6月30日 週一 下午7:29寫道：
>
> On 30/06/2025 13:20, tzuhao.wtmh@gmail.com wrote:
> > From: Henry Wu <Henry_Wu@quantatw.com>
> >
> > Add support for the mp2869a and mp29612a controllers from Monolithic Power
> > Systems, Inc. (MPS). These are dual-loop, digital, multi-phase modulation
> > controllers.
> >
> > ---
> >
> > Changes in v2:
> > - Fix coding style issues.
>
> Which ones? How?

I used checkpatch.pl with the "--strict" option and made the following
adjustments:
- Removed illegal spaces
- Converted comments to block style using /** ... */ instead of //
- Applied lowercase formatting to function names
Would you like me to list all the changes here, or should I include
them in the next patch?

>
> > - Using the pointer to replace the memcpy.
> > - Fix wrong device tree entries.
>
> What exactly? How did you fix it? I see zero changes. Your changelog
> should be specific, not vague.
In patch v1, I placed the mp2869a entry in the wrong order in
trivial-devices.yaml. In patch v2, I reordered it based on the
numerical order in the device name
>
>
> Best regards,
> Krzysztof

Best regards,
Henry Wu

Re: [PATCH v2 1/2] hwmon: (pmbus) Add support for MPS multi-phase mp2869a/mp29612a controllers

[Guenter Roeck]

On 6/30/25 04:20, tzuhao.wtmh@gmail.com wrote:
> From: Henry Wu <Henry_Wu@quantatw.com>
> 
> Add support for the mp2869a and mp29612a controllers from Monolithic Power
> Systems, Inc. (MPS). These are dual-loop, digital, multi-phase modulation
> controllers.
> 
> Signed-off-by: Henry Wu <Henry_Wu@quantatw.com>
> ---
>   Documentation/hwmon/index.rst   |   1 +
>   Documentation/hwmon/mp2869a.rst |  86 +++++++++
>   drivers/hwmon/pmbus/Kconfig     |  10 ++
>   drivers/hwmon/pmbus/Makefile    |   1 +
>   drivers/hwmon/pmbus/mp2869a.c   | 299 ++++++++++++++++++++++++++++++++
>   5 files changed, 397 insertions(+)
>   create mode 100644 Documentation/hwmon/mp2869a.rst
>   create mode 100644 drivers/hwmon/pmbus/mp2869a.c
> 
> diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
> index b45bfb4ebf30..10bf4bd77f7b 100644
> --- a/Documentation/hwmon/index.rst
> +++ b/Documentation/hwmon/index.rst
> @@ -172,6 +172,7 @@ Hardware Monitoring Kernel Drivers
>      menf21bmc
>      mlxreg-fan
>      mp2856
> +   mp2869a
>      mp2888
>      mp2891
>      mp2975
> diff --git a/Documentation/hwmon/mp2869a.rst b/Documentation/hwmon/mp2869a.rst
> new file mode 100644
> index 000000000000..a98ccb3d630d
> --- /dev/null
> +++ b/Documentation/hwmon/mp2869a.rst
> @@ -0,0 +1,86 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +Kernel driver mp2896a
> +=====================
> +
> +Supported chips:
> +
> +  * MPS MP2896A
> +
> +    Prefix: 'mp2896a'
> +
> +  * MPS MP29612A
> +
> +    Prefix: 'mp29612a'
> +
> +Author:
> +
> +    Henry Wu <Henry_WU@quantatw.com>
> +
> +Description
> +-----------
> +
> +This driver implements support for Monolithic Power Systems, Inc. (MPS)
> +MP2896A, a digital, multi-phase voltage regulator controller with PMBus interface.
> +
> +This device:
> +
> +- Supports up to two power rails.
> +- Supports multiple PMBus pages for telemetry and configuration.
> +- Supports VOUT readout in **VID format only** (no support for direct format).
> +- Supports AMD SVI3 VID protocol with 5-mV/LSB resolution (if applicable).
> +- Uses vendor-specific registers for VOUT scaling and phase configuration.
> +
> +Device supports:
> +
> +- SVID interface.
> +- AVSBus interface.
> +
> +Device compliant with:
> +
> +- PMBus rev 1.3 interface.
> +
> +Sysfs Interface
> +---------------
> +
> +The driver provides the following sysfs attributes:
> +
> +**Current measurements:**
> +
> +- Index 1: "iin"
> +- Indexes 2, 3: "iout"
> +
> +**curr[1-3]_alarm**
> +**curr[1-3]_input**
> +**curr[1-3]_label**
> +
> +**Voltage measurements:**
> +
> +- Index 1: "vin"
> +- Indexes 2, 3: "vout"
> +
> +**in[1-3]_crit**
> +**in[1-3]_crit_alarm**
> +**in[1-3]_input**
> +**in[1-3]_label**
> +**in[1-3]_lcrit**
> +**in[1-3]_lcrit_alarm**
> +
> +**Power measurements:**
> +
> +- Index 1: "pin"
> +- Indexes 2, 3: "pout"
> +
> +**power[1-3]_alarm**
> +**power[1-3]_input**
> +**power[1-3]_label**
> +
> +**Temperature measurements:**
> +
> +**temp[1-2]_crit**
> +**temp[1-2]_crit_alarm**
> +**temp[1-2]_input**
> +**temp[1-2]_max**
> +**temp[1-2]_max_alarm**
> +
> +
> diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
> index 441f984a859d..93b558761cc6 100644
> --- a/drivers/hwmon/pmbus/Kconfig
> +++ b/drivers/hwmon/pmbus/Kconfig
> @@ -364,6 +364,16 @@ config SENSORS_MP2856
>   	  This driver can also be built as a module. If so, the module will
>   	  be called mp2856.
>   
> +config SENSORS_MP2869A
> +	tristate "MP2869A PMBus sensor"
> +	depends on I2C && PMBUS
> +	help
> +	  If you say yes here you get support for the MPS MP2869A MP29612A
> +	  voltage regulator via the PMBus interface.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called mp2869a.
> +
>   config SENSORS_MP2888
>   	tristate "MPS MP2888"
>   	help
> diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
> index 29cd8a3317d2..42087d0dedbc 100644
> --- a/drivers/hwmon/pmbus/Makefile
> +++ b/drivers/hwmon/pmbus/Makefile
> @@ -37,6 +37,7 @@ obj-$(CONFIG_SENSORS_MAX31785)	+= max31785.o
>   obj-$(CONFIG_SENSORS_MAX34440)	+= max34440.o
>   obj-$(CONFIG_SENSORS_MAX8688)	+= max8688.o
>   obj-$(CONFIG_SENSORS_MP2856)	+= mp2856.o
> +obj-$(CONFIG_SENSORS_MP2869A)   += mp2869a.o
>   obj-$(CONFIG_SENSORS_MP2888)	+= mp2888.o
>   obj-$(CONFIG_SENSORS_MP2891)	+= mp2891.o
>   obj-$(CONFIG_SENSORS_MP2975)	+= mp2975.o
> diff --git a/drivers/hwmon/pmbus/mp2869a.c b/drivers/hwmon/pmbus/mp2869a.c
> new file mode 100644
> index 000000000000..e61f1380dbc1
> --- /dev/null
> +++ b/drivers/hwmon/pmbus/mp2869a.c
> @@ -0,0 +1,299 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Hardware monitoring driver for MP2856A/MP29612A
> + * Monolithic Power Systems VR Controller
> + *
> + * Copyright (C) 2023 Quanta Computer lnc.
> + */
> +
> +#include <linux/err.h>
> +#include <linux/i2c.h>
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/pmbus.h>
> +#include "pmbus.h"
> +
> +/* Vendor specific registers. */
> +#define MP2869A_VOUT_MODE			 0x20

Standard register.

> +#define MP2869A_VOUT_MODE_MASK		 GENMASK(7, 5)
> +#define MP2869A_VOUT_MODE_VID		 (0 << 5)
> +
> +#define MP2869A_READ_VOUT			 0x8b

Standard register.
> +
> +#define MP2869A_MFR_VOUT_SCALE_LOOP	 0x29

Standard register.

Guenter

Re: [PATCH v2 1/2] hwmon: (pmbus) Add support for MPS multi-phase mp2869a/mp29612a controllers

[Guenter Roeck]

On 6/30/25 04:20, tzuhao.wtmh@gmail.com wrote:
> From: Henry Wu <Henry_Wu@quantatw.com>
> 
> Add support for the mp2869a and mp29612a controllers from Monolithic Power
> Systems, Inc. (MPS). These are dual-loop, digital, multi-phase modulation
> controllers.
> 

This patch needs to be consolidated with the MP2869 part of
https://patchwork.kernel.org/project/linux-hwmon/patch/20250709093420.456304-2-wenswang@yeah.net/
That patch uses the _identify function from the PMBus core instead of re-implementing
it, which is a plus. It also takes more chip configuration details into account.
But then it only supports mp2869 and not mp2869a or mp29612a.

The chips do not officially exist, so I have a difficult time to determine
what is actually needed or even makes sense. You'll have to determine that
with the submitter of the other driver.

Frankly, I am not even sure if I should accept drivers for chips which are
so super-secret that the manufacturer does not even admit their existence.

Guenter