[PATCH v3 0/3] Add Silergy SQ24860 support

[PATCH v3 0/3] Add Silergy SQ24860 support

[Ziming Zhu]

From: Ziming Zhu <ziming.zhu@silergycorp.com>

Add devicetree bindings, PMBus hwmon driver support, and documentation
for the Silergy SQ24860 eFuse.

The device provides voltage, current, power, and temperature telemetry.
The driver also supports peak, average, and minimum history reporting,
sample count configuration, and maps the manufacturer-specific VIREF
register to the generic input over-current fault limit attribute.

Changes in v3:
- fix remaining checkpatch issues in the SQ24860 driver
- use C comments consistently in the driver
- drop unused header files
- make GIMON a constant in the gain calculation helper
- use proper 64-bit division for the calibration gain calculation
- return -EINVAL when the calculated gain does not fit
- reject PMBUS_IIN_OC_FAULT_LIMIT values outside the hardware range
- treat malformed silergy,rimon-micro-ohms as an error
- sort sq24860 correctly in Documentation/hwmon/index.rst

Ziming Zhu (3):
  dt-bindings: hwmon: pmbus: Add bindings for Silergy SQ24860
  hwmon: pmbus: Add support for Silergy SQ24860
  hwmon: Add documentation for SQ24860

 .../bindings/hwmon/pmbus/silergy,sq24860.yaml |  74 +++
 Documentation/hwmon/index.rst                 |   1 +
 Documentation/hwmon/sq24860.rst               |  96 ++++
 drivers/hwmon/pmbus/Kconfig                   |  19 +
 drivers/hwmon/pmbus/Makefile                  |   1 +
 drivers/hwmon/pmbus/sq24860.c                 | 430 ++++++++++++++++++
 6 files changed, 621 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/pmbus/silergy,sq24860.yaml
 create mode 100644 Documentation/hwmon/sq24860.rst
 create mode 100644 drivers/hwmon/pmbus/sq24860.c

-- 
2.25.1

[PATCH v3 1/3] dt-bindings: hwmon: pmbus: Add bindings for Silergy SQ24860

[Ziming Zhu]

From: Ziming Zhu <ziming.zhu@silergycorp.com>

Add devicetree binding documentation for the Silergy SQ24860 eFuse.

The device is a PMBus hardware monitoring device which reports voltage,
current, power, and temperature telemetry. The board-specific IMON
resistor value is described with silergy,rimon-micro-ohms.

Signed-off-by: Ziming Zhu <ziming.zhu@silergycorp.com>
---
 .../bindings/hwmon/pmbus/silergy,sq24860.yaml | 74 +++++++++++++++++++
 1 file changed, 74 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/pmbus/silergy,sq24860.yaml

diff --git a/Documentation/devicetree/bindings/hwmon/pmbus/silergy,sq24860.yaml b/Documentation/devicetree/bindings/hwmon/pmbus/silergy,sq24860.yaml
new file mode 100644
index 000000000000..03ef82c11e1a
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/pmbus/silergy,sq24860.yaml
@@ -0,0 +1,74 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+
+$id: http://devicetree.org/schemas/hwmon/pmbus/silergy,sq24860.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Silergy SQ24860 eFuse
+
+maintainers:
+  - Ziming Zhu <ziming.zhu@silergycorp.com>
+
+description:
+  The Silergy SQ24860 is an integrated, high-current circuit protection and
+  power management device with PMBus interface.
+
+properties:
+  compatible:
+    const: silergy,sq24860
+
+  reg:
+    maxItems: 1
+
+  silergy,rimon-micro-ohms:
+    description:
+      Micro-ohms value of the resistance installed between the IMON pin and
+      the ground reference.
+
+  interrupts:
+    description: PMBus SMBAlert interrupt.
+    maxItems: 1
+
+  regulators:
+    type: object
+    description:
+      List of regulators provided by this controller.
+
+    properties:
+      vout:
+        $ref: /schemas/regulator/regulator.yaml#
+        type: object
+        unevaluatedProperties: false
+
+    additionalProperties: false
+
+required:
+  - compatible
+  - reg
+  - silergy,rimon-micro-ohms
+
+additionalProperties: false
+
+examples:
+  - |
+
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        hw-monitor@40 {
+            compatible = "silergy,sq24860";
+            reg = <0x40>;
+
+            interrupt-parent = <&gpio>;
+            interrupts = <42 8>;
+            silergy,rimon-micro-ohms = <1600000000>;
+
+            regulators {
+                cpu0_vout: vout {
+                    regulator-name = "main_cpu0";
+                };
+            };
+        };
+    };
-- 
2.25.1

Re: [PATCH v3 1/3] dt-bindings: hwmon: pmbus: Add bindings for Silergy SQ24860

[sashiko-bot]

> From: Ziming Zhu <ziming.zhu@silergycorp.com>
> 
> Add devicetree binding documentation for the Silergy SQ24860 eFuse.
> 
> The device is a PMBus hardware monitoring device which reports voltage,
> current, power, and temperature telemetry. The board-specific IMON
> resistor value is described with silergy,rimon-micro-ohms.
> 
> Signed-off-by: Ziming Zhu <ziming.zhu@silergycorp.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260611074335.4415-1-zmzhu0630@163.com?part=1

[PATCH v3 2/3] hwmon: pmbus: Add support for Silergy SQ24860

[Ziming Zhu]

From: Ziming Zhu <ziming.zhu@silergycorp.com>

Add PMBus hwmon support for the Silergy SQ24860 eFuse.

The driver reports input voltage, output voltage, auxiliary voltage,
input current, input power, and temperature. It also exposes peak,
average, and minimum history attributes, sample count configuration,
and maps the manufacturer-specific VIREF register to the generic input
over-current fault limit attribute.

The IMON resistor value is read from the silergy,rimon-micro-ohms device
property and used to configure the input current calibration gain.

Signed-off-by: Ziming Zhu <ziming.zhu@silergycorp.com>
---
 drivers/hwmon/pmbus/Kconfig   |  19 ++
 drivers/hwmon/pmbus/Makefile  |   1 +
 drivers/hwmon/pmbus/sq24860.c | 430 ++++++++++++++++++++++++++++++++++
 3 files changed, 450 insertions(+)
 create mode 100644 drivers/hwmon/pmbus/sq24860.c

diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
index 8f4bff375ecb..a905b5af137c 100644
--- a/drivers/hwmon/pmbus/Kconfig
+++ b/drivers/hwmon/pmbus/Kconfig
@@ -612,6 +612,25 @@ config SENSORS_STEF48H28
 	  This driver can also be built as a module. If so, the module will
 	  be called stef48h28.
 
+config SENSORS_SQ24860
+	tristate "Silergy SQ24860"
+	help
+	  If you say yes here you get hardware monitoring support for Silergy
+	  SQ24860 eFuse.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called sq24860.
+
+config SENSORS_SQ24860_REGULATOR
+	bool "Regulator support for SQ24860"
+	depends on SENSORS_SQ24860 && REGULATOR
+	default SENSORS_SQ24860
+	help
+	  If you say yes here you get regulator support for Silergy SQ24860.
+	  The regulator is registered through the PMBus regulator framework and
+	  can be used to control the output exposed by the device.
+	  This option is only useful if regulator framework support is needed.
+
 config SENSORS_STPDDC60
 	tristate "ST STPDDC60"
 	help
diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
index 7129b62bc00f..86bc93c6c091 100644
--- a/drivers/hwmon/pmbus/Makefile
+++ b/drivers/hwmon/pmbus/Makefile
@@ -60,6 +60,7 @@ 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-$(CONFIG_SENSORS_SQ24860)	+= sq24860.o
 obj-$(CONFIG_SENSORS_STPDDC60)	+= stpddc60.o
 obj-$(CONFIG_SENSORS_TDA38640)	+= tda38640.o
 obj-$(CONFIG_SENSORS_TPS25990)	+= tps25990.o
diff --git a/drivers/hwmon/pmbus/sq24860.c b/drivers/hwmon/pmbus/sq24860.c
new file mode 100644
index 000000000000..f16f650ff7ba
--- /dev/null
+++ b/drivers/hwmon/pmbus/sq24860.c
@@ -0,0 +1,430 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Author: Ziming Zhu <ziming.zhu@silergycorp.com>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/math64.h>
+
+#include "pmbus.h"
+
+#define SQ24860_IIN_CAL_GAIN		0x38
+#define SQ24860_READ_VAUX		0xd0
+#define SQ24860_READ_VIN_MIN		0xd1
+#define SQ24860_READ_VIN_PEAK		0xd2
+#define SQ24860_READ_IIN_PEAK		0xd4
+#define SQ24860_READ_PIN_PEAK		0xd5
+#define SQ24860_READ_TEMP_AVG		0xd6
+#define SQ24860_READ_TEMP_PEAK		0xd7
+#define SQ24860_READ_VOUT_MIN		0xda
+#define SQ24860_READ_VIN_AVG		0xdc
+#define SQ24860_READ_VOUT_AVG		0xdd
+#define SQ24860_READ_IIN_AVG		0xde
+#define SQ24860_READ_PIN_AVG		0xdf
+#define SQ24860_VIREF			0xe0
+#define SQ24860_PK_MIN_AVG		0xea
+#define PK_MIN_AVG_RST_PEAK		BIT(7)
+#define PK_MIN_AVG_RST_AVG		BIT(6)
+#define PK_MIN_AVG_RST_MIN		BIT(5)
+#define PK_MIN_AVG_AVG_CNT		GENMASK(2, 0)
+#define SQ24860_MFR_WRITE_PROTECT	0xf8
+#define SQ24860_UNLOCKED		BIT(7)
+
+#define SQ24860_8B_SHIFT		2
+#define SQ24860_IIN_OCF_NUM		1000000
+#define SQ24860_IIN_OCF_DIV		129278
+#define SQ24860_IIN_OCF_OFF		165
+
+#define PK_MIN_AVG_RST_MASK		(PK_MIN_AVG_RST_PEAK | \
+					 PK_MIN_AVG_RST_AVG  | \
+					 PK_MIN_AVG_RST_MIN)
+#define SQ24860_MAX_SAMPLES		BIT(FIELD_MAX(PK_MIN_AVG_AVG_CNT))
+/*
+ * Arbitrary default Rimon value: 1.6kOhm
+ */
+#define SQ24860_DEFAULT_RIMON		1600000000
+#define SQ24860_GIMON			18180
+
+#define SQ24860_VAUX_DIV		20
+
+static int sq24860_write_iin_cal_gain(struct i2c_client *client, u32 rimon)
+{
+	u64 temp = 6400ULL * 1000000000ULL * 1000ULL;
+	u64 denom;
+	u64 word;
+
+	if (!rimon)
+		return -EINVAL;
+
+	denom = (u64)rimon * SQ24860_GIMON;
+	word = div64_u64(temp, denom);
+	if (!word || word > U16_MAX)
+		return -EINVAL;
+
+	return i2c_smbus_write_word_data(client, SQ24860_IIN_CAL_GAIN,
+					(u16)word);
+}
+
+static int sq24860_mfr_write_protect_set(struct i2c_client *client,
+					u8 protect)
+{
+	u8 val;
+
+	switch (protect) {
+	case 0:
+		val = 0xa2;
+		break;
+	case PB_WP_ALL:
+		val = 0x0;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return pmbus_write_byte_data(client, -1, SQ24860_MFR_WRITE_PROTECT,
+				     val);
+}
+
+static int sq24860_mfr_write_protect_get(struct i2c_client *client)
+{
+	int ret = pmbus_read_byte_data(client, -1, SQ24860_MFR_WRITE_PROTECT);
+
+	if (ret < 0)
+		return ret;
+
+	return (ret & SQ24860_UNLOCKED) ? 0 : PB_WP_ALL;
+}
+
+static int sq24860_read_word_data(struct i2c_client *client,
+				   int page, int phase, int reg)
+{
+	int ret;
+
+	switch (reg) {
+	case PMBUS_VIRT_READ_VIN_MAX:
+		ret = pmbus_read_word_data(client, page, phase,
+					   SQ24860_READ_VIN_PEAK);
+		break;
+
+	case PMBUS_VIRT_READ_VIN_MIN:
+		ret = pmbus_read_word_data(client, page, phase,
+					   SQ24860_READ_VIN_MIN);
+		break;
+
+	case PMBUS_VIRT_READ_VIN_AVG:
+		ret = pmbus_read_word_data(client, page, phase,
+					   SQ24860_READ_VIN_AVG);
+		break;
+
+	case PMBUS_VIRT_READ_VOUT_MIN:
+		ret = pmbus_read_word_data(client, page, phase,
+					   SQ24860_READ_VOUT_MIN);
+		break;
+
+	case PMBUS_VIRT_READ_VOUT_AVG:
+		ret = pmbus_read_word_data(client, page, phase,
+					   SQ24860_READ_VOUT_AVG);
+		break;
+
+	case PMBUS_VIRT_READ_IIN_AVG:
+		ret = pmbus_read_word_data(client, page, phase,
+					   SQ24860_READ_IIN_AVG);
+		break;
+
+	case PMBUS_VIRT_READ_IIN_MAX:
+		ret = pmbus_read_word_data(client, page, phase,
+					   SQ24860_READ_IIN_PEAK);
+		break;
+
+	case PMBUS_VIRT_READ_TEMP_AVG:
+		ret = pmbus_read_word_data(client, page, phase,
+					   SQ24860_READ_TEMP_AVG);
+		break;
+
+	case PMBUS_VIRT_READ_TEMP_MAX:
+		ret = pmbus_read_word_data(client, page, phase,
+					   SQ24860_READ_TEMP_PEAK);
+		break;
+
+	case PMBUS_VIRT_READ_PIN_AVG:
+		ret = pmbus_read_word_data(client, page, phase,
+					   SQ24860_READ_PIN_AVG);
+		break;
+
+	case PMBUS_VIRT_READ_PIN_MAX:
+		ret = pmbus_read_word_data(client, page, phase,
+					   SQ24860_READ_PIN_PEAK);
+		break;
+
+	case PMBUS_VIRT_READ_VMON:
+		ret = pmbus_read_word_data(client, page, phase,
+					   SQ24860_READ_VAUX);
+		if (ret < 0)
+			break;
+		ret = DIV_ROUND_CLOSEST(ret, SQ24860_VAUX_DIV);
+		break;
+
+	case PMBUS_VIN_UV_WARN_LIMIT:
+	case PMBUS_VIN_UV_FAULT_LIMIT:
+	case PMBUS_VIN_OV_WARN_LIMIT:
+	case PMBUS_VIN_OV_FAULT_LIMIT:
+	case PMBUS_VOUT_UV_WARN_LIMIT:
+	case PMBUS_IIN_OC_WARN_LIMIT:
+	case PMBUS_OT_WARN_LIMIT:
+	case PMBUS_OT_FAULT_LIMIT:
+	case PMBUS_PIN_OP_WARN_LIMIT:
+		/*
+		 * These registers provide an 8 bits value instead of a
+		 * 10bits one. Just shifting twice the register value is
+		 * enough to make the sensor type conversion work, even
+		 * if the datasheet provides different m, b and R for
+		 * those.
+		 */
+		ret = pmbus_read_word_data(client, page, phase, reg);
+		if (ret < 0)
+			break;
+		ret <<= SQ24860_8B_SHIFT;
+		break;
+
+	case PMBUS_IIN_OC_FAULT_LIMIT:
+		/*
+		 * VIREF directly sets the over-current limit at which the eFuse
+		 * will turn the FET off and trigger a fault. Expose it through
+		 * this generic property instead of a manufacturer specific one.
+		 */
+		ret = pmbus_read_byte_data(client, page, SQ24860_VIREF);
+		if (ret < 0)
+			break;
+		ret = DIV_ROUND_CLOSEST(ret * SQ24860_IIN_OCF_NUM,
+					SQ24860_IIN_OCF_DIV);
+		ret += SQ24860_IIN_OCF_OFF;
+		break;
+
+	case PMBUS_VIRT_SAMPLES:
+		ret = pmbus_read_byte_data(client, page, SQ24860_PK_MIN_AVG);
+		if (ret < 0)
+			break;
+		ret = BIT(FIELD_GET(PK_MIN_AVG_AVG_CNT, ret));
+		break;
+
+	case PMBUS_VIRT_RESET_TEMP_HISTORY:
+	case PMBUS_VIRT_RESET_VIN_HISTORY:
+	case PMBUS_VIRT_RESET_IIN_HISTORY:
+	case PMBUS_VIRT_RESET_PIN_HISTORY:
+	case PMBUS_VIRT_RESET_VOUT_HISTORY:
+		ret = 0;
+		break;
+
+	default:
+		ret = -ENODATA;
+		break;
+	}
+
+	return ret;
+}
+
+static int sq24860_write_word_data(struct i2c_client *client,
+				    int page, int reg, u16 value)
+{
+	int ret;
+
+	switch (reg) {
+	case PMBUS_VIN_UV_WARN_LIMIT:
+	case PMBUS_VIN_UV_FAULT_LIMIT:
+	case PMBUS_VIN_OV_WARN_LIMIT:
+	case PMBUS_VIN_OV_FAULT_LIMIT:
+	case PMBUS_VOUT_UV_WARN_LIMIT:
+	case PMBUS_IIN_OC_WARN_LIMIT:
+	case PMBUS_OT_WARN_LIMIT:
+	case PMBUS_OT_FAULT_LIMIT:
+	case PMBUS_PIN_OP_WARN_LIMIT:
+		value >>= SQ24860_8B_SHIFT;
+		value = clamp_val(value, 0, 0xff);
+		ret = pmbus_write_word_data(client, page, reg, value);
+		break;
+
+	case PMBUS_IIN_OC_FAULT_LIMIT:
+		if (value < SQ24860_IIN_OCF_OFF)
+			return -EINVAL;
+		value -= SQ24860_IIN_OCF_OFF;
+		value = DIV_ROUND_CLOSEST(((unsigned int)value) * SQ24860_IIN_OCF_DIV,
+					  SQ24860_IIN_OCF_NUM);
+		value = clamp_val(value, 0, 0x3f);
+		ret = pmbus_write_byte_data(client, page, SQ24860_VIREF, value);
+		break;
+
+	case PMBUS_VIRT_SAMPLES:
+		value = clamp_val(value, 1, SQ24860_MAX_SAMPLES);
+		value = ilog2(value);
+		ret = pmbus_update_byte_data(client, page, SQ24860_PK_MIN_AVG,
+					     PK_MIN_AVG_AVG_CNT,
+					     FIELD_PREP(PK_MIN_AVG_AVG_CNT, value));
+		break;
+
+	case PMBUS_VIRT_RESET_TEMP_HISTORY:
+	case PMBUS_VIRT_RESET_VIN_HISTORY:
+	case PMBUS_VIRT_RESET_IIN_HISTORY:
+	case PMBUS_VIRT_RESET_PIN_HISTORY:
+	case PMBUS_VIRT_RESET_VOUT_HISTORY:
+		/*
+		 * SQ24860 has history resets based on MIN/AVG/PEAK instead of per
+		 * sensor type. Exposing this quirk in hwmon is not desirable so
+		 * reset MIN, AVG and PEAK together. Even is there effectively only
+		 * one reset, which resets everything, expose the 5 entries so
+		 * userspace is not required map a sensor type to another to trigger
+		 * a reset
+		 */
+		ret = pmbus_update_byte_data(client, 0, SQ24860_PK_MIN_AVG,
+					     PK_MIN_AVG_RST_MASK,
+					     PK_MIN_AVG_RST_MASK);
+		break;
+
+	default:
+		ret = -ENODATA;
+		break;
+	}
+
+	return ret;
+}
+
+static int sq24860_read_byte_data(struct i2c_client *client,
+				   int page, int reg)
+{
+	int ret;
+
+	switch (reg) {
+	case PMBUS_WRITE_PROTECT:
+		ret = sq24860_mfr_write_protect_get(client);
+		break;
+
+	default:
+		ret = -ENODATA;
+		break;
+	}
+
+	return ret;
+}
+
+static int sq24860_write_byte_data(struct i2c_client *client,
+				    int page, int reg, u8 byte)
+{
+	int ret;
+
+	switch (reg) {
+	case PMBUS_WRITE_PROTECT:
+		ret = sq24860_mfr_write_protect_set(client, byte);
+		break;
+
+	default:
+		ret = -ENODATA;
+		break;
+	}
+
+	return ret;
+}
+
+#if IS_ENABLED(CONFIG_SENSORS_SQ24860_REGULATOR)
+static const struct regulator_desc sq24860_reg_desc[] = {
+	PMBUS_REGULATOR_ONE_NODE("vout"),
+};
+#endif
+
+static const struct pmbus_driver_info sq24860_base_info = {
+	.pages = 1,
+	.format[PSC_VOLTAGE_IN] = direct,
+	.m[PSC_VOLTAGE_IN] = 64,
+	.b[PSC_VOLTAGE_IN] = 0,
+	.R[PSC_VOLTAGE_IN] = 0,
+	.format[PSC_VOLTAGE_OUT] = direct,
+	.m[PSC_VOLTAGE_OUT] = 64,
+	.b[PSC_VOLTAGE_OUT] = 0,
+	.R[PSC_VOLTAGE_OUT] = 0,
+	.format[PSC_TEMPERATURE] = direct,
+	.m[PSC_TEMPERATURE] = 1,
+	.b[PSC_TEMPERATURE] = 0,
+	.R[PSC_TEMPERATURE] = 0,
+/*
+ * Current and power measurements depend on the calibration gain
+ * programmed from the board-specific IMON resistor value.
+ */
+	.format[PSC_CURRENT_IN] = direct,
+	.m[PSC_CURRENT_IN] = 16,
+	.b[PSC_CURRENT_IN] = 0,
+	.R[PSC_CURRENT_IN] = 0,
+	.format[PSC_POWER] = direct,
+	.m[PSC_POWER] = 2,
+	.b[PSC_POWER] = 0,
+	.R[PSC_POWER] = 0,
+	.func[0] = PMBUS_HAVE_VIN |
+		   PMBUS_HAVE_VOUT |
+		   PMBUS_HAVE_VMON |
+		   PMBUS_HAVE_IIN |
+		   PMBUS_HAVE_PIN |
+		   PMBUS_HAVE_TEMP |
+		   PMBUS_HAVE_STATUS_VOUT |
+		   PMBUS_HAVE_STATUS_IOUT |
+		   PMBUS_HAVE_STATUS_INPUT |
+		   PMBUS_HAVE_STATUS_TEMP |
+		   PMBUS_HAVE_SAMPLES,
+	.read_word_data = sq24860_read_word_data,
+	.write_word_data = sq24860_write_word_data,
+	.read_byte_data = sq24860_read_byte_data,
+	.write_byte_data = sq24860_write_byte_data,
+
+#if IS_ENABLED(CONFIG_SENSORS_SQ24860_REGULATOR)
+	.reg_desc = sq24860_reg_desc,
+	.num_regulators = ARRAY_SIZE(sq24860_reg_desc),
+#endif
+};
+
+static const struct i2c_device_id sq24860_i2c_id[] = {
+	{ "sq24860" },
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, sq24860_i2c_id);
+
+static const struct of_device_id sq24860_of_match[] = {
+	{ .compatible = "silergy,sq24860" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, sq24860_of_match);
+
+static int sq24860_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct pmbus_driver_info *info;
+	u32 rimon;
+	int ret;
+
+	if (device_property_read_u32(dev, "silergy,rimon-micro-ohms", &rimon))
+		rimon = SQ24860_DEFAULT_RIMON;
+	ret = sq24860_write_iin_cal_gain(client, rimon);
+	if (ret < 0)
+		return dev_err_probe(&client->dev, ret,
+					     "Failed to set gain\n");
+	info = devm_kmemdup(dev, &sq24860_base_info, sizeof(*info), GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	return pmbus_do_probe(client, info);
+}
+
+static struct i2c_driver sq24860_driver = {
+	.driver = {
+		.name = "sq24860",
+		.of_match_table = sq24860_of_match,
+	},
+	.probe = sq24860_probe,
+	.id_table = sq24860_i2c_id,
+};
+module_i2c_driver(sq24860_driver);
+
+MODULE_AUTHOR("Ziming Zhu <ziming.zhu@silergycorp.com>");
+MODULE_DESCRIPTION("PMBUS driver for SQ24860 eFuse");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("PMBUS");
-- 
2.25.1

Re: [PATCH v3 2/3] hwmon: pmbus: Add support for Silergy SQ24860

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
- [High] Missing signedness check on PMBus limits causes negative inputs to silently set maximum hardware limits.
- [Medium] Returns -EINVAL instead of clamping for out-of-bounds lower limits in PMBUS_IIN_OC_FAULT_LIMIT.
--

commit 1edf6322da1b629fce9b16a96496a18863aacef8
Author: Ziming Zhu <ziming.zhu@silergycorp.com>

hwmon: pmbus: Add support for Silergy SQ24860
    
Add PMBus hwmon support for the Silergy SQ24860 eFuse. The driver reports
voltage, current, power, and temperature, along with history attributes
and over-current fault limits.

> diff --git a/drivers/hwmon/pmbus/sq24860.c b/drivers/hwmon/pmbus/sq24860.c
> new file mode 100644
> index 0000000000000..f16f650ff7ba2
> --- /dev/null
> +++ b/drivers/hwmon/pmbus/sq24860.c
[ ... ]
> +static int sq24860_write_word_data(struct i2c_client *client,
> +				    int page, int reg, u16 value)
> +{
> +	int ret;
> +
> +	switch (reg) {
> +	case PMBUS_VIN_UV_WARN_LIMIT:
> +	case PMBUS_VIN_UV_FAULT_LIMIT:
> +	case PMBUS_VIN_OV_WARN_LIMIT:
> +	case PMBUS_VIN_OV_FAULT_LIMIT:
> +	case PMBUS_VOUT_UV_WARN_LIMIT:
> +	case PMBUS_IIN_OC_WARN_LIMIT:
> +	case PMBUS_OT_WARN_LIMIT:
> +	case PMBUS_OT_FAULT_LIMIT:
> +	case PMBUS_PIN_OP_WARN_LIMIT:
> +		value >>= SQ24860_8B_SHIFT;
> +		value = clamp_val(value, 0, 0xff);

[Severity: High]
Does this handle negative user inputs correctly?

The PMBus core converts limit values into 16-bit 2's complement integers
(s16), but passes them as u16 to sq24860_write_word_data(). Because this
driver treats value as an unsigned u16, a negative user limit written via
sysfs will become a large positive value (e.g., 0xFFFF).

When this large value is logically right-shifted and clamped here, it
results in setting the maximum possible hardware limit (0xff) instead of
clamping to the minimum limit (0).

> +		ret = pmbus_write_word_data(client, page, reg, value);
> +		break;
> +
> +	case PMBUS_IIN_OC_FAULT_LIMIT:
> +		if (value < SQ24860_IIN_OCF_OFF)
> +			return -EINVAL;

[Severity: High]
Could a negative user limit bypass this bounds check?

Since value is unsigned, a negative limit (e.g., 0xFFFF) will evaluate
as greater than SQ24860_IIN_OCF_OFF (165). This bypasses the check below
and overflows the 32-bit unsigned calculation, effectively disabling
over-current protection by incorrectly setting the hardware limit to its
maximum.

[Severity: Medium]
Should this clamp the value instead of returning an error?

The hwmon sysfs ABI convention requires drivers to silently clamp
out-of-range user limits to the nearest supported hardware value rather
than returning an error.

If the requested limit translates to a value below SQ24860_IIN_OCF_OFF,
returning -EINVAL violates this convention. Would it be better to clamp
the limit to SQ24860_IIN_OCF_OFF so the underlying register is set to 0?

> +		value -= SQ24860_IIN_OCF_OFF;
> +		value = DIV_ROUND_CLOSEST(((unsigned int)value) * SQ24860_IIN_OCF_DIV,
> +					  SQ24860_IIN_OCF_NUM);
> +		value = clamp_val(value, 0, 0x3f);
> +		ret = pmbus_write_byte_data(client, page, SQ24860_VIREF, value);
> +		break;

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260611074335.4415-1-zmzhu0630@163.com?part=2

Re: [PATCH v3 2/3] hwmon: pmbus: Add support for Silergy SQ24860

[Guenter Roeck]

On 6/11/26 00:54, sashiko-bot@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider:
> - [High] Missing signedness check on PMBus limits causes negative inputs to silently set maximum hardware limits.
> - [Medium] Returns -EINVAL instead of clamping for out-of-bounds lower limits in PMBUS_IIN_OC_FAULT_LIMIT.
> --
> 
> commit 1edf6322da1b629fce9b16a96496a18863aacef8
> Author: Ziming Zhu <ziming.zhu@silergycorp.com>
> 
> hwmon: pmbus: Add support for Silergy SQ24860
>      
> Add PMBus hwmon support for the Silergy SQ24860 eFuse. The driver reports
> voltage, current, power, and temperature, along with history attributes
> and over-current fault limits.
> 
>> diff --git a/drivers/hwmon/pmbus/sq24860.c b/drivers/hwmon/pmbus/sq24860.c
>> new file mode 100644
>> index 0000000000000..f16f650ff7ba2
>> --- /dev/null
>> +++ b/drivers/hwmon/pmbus/sq24860.c
> [ ... ]
>> +static int sq24860_write_word_data(struct i2c_client *client,
>> +				    int page, int reg, u16 value)
>> +{
>> +	int ret;
>> +
>> +	switch (reg) {
>> +	case PMBUS_VIN_UV_WARN_LIMIT:
>> +	case PMBUS_VIN_UV_FAULT_LIMIT:
>> +	case PMBUS_VIN_OV_WARN_LIMIT:
>> +	case PMBUS_VIN_OV_FAULT_LIMIT:
>> +	case PMBUS_VOUT_UV_WARN_LIMIT:
>> +	case PMBUS_IIN_OC_WARN_LIMIT:
>> +	case PMBUS_OT_WARN_LIMIT:
>> +	case PMBUS_OT_FAULT_LIMIT:
>> +	case PMBUS_PIN_OP_WARN_LIMIT:
>> +		value >>= SQ24860_8B_SHIFT;
>> +		value = clamp_val(value, 0, 0xff);
> 
> [Severity: High]
> Does this handle negative user inputs correctly?
> 
> The PMBus core converts limit values into 16-bit 2's complement integers
> (s16), but passes them as u16 to sq24860_write_word_data(). Because this
> driver treats value as an unsigned u16, a negative user limit written via
> sysfs will become a large positive value (e.g., 0xFFFF).
> 
> When this large value is logically right-shifted and clamped here, it
> results in setting the maximum possible hardware limit (0xff) instead of
> clamping to the minimum limit (0).
> 

Without a datasheet it is all but impossible to determine how to handle
this. Is the 8-bit value signed or not ? Who knows. The read function
suggests that it is unsigned, given that the sign bit is not extended,
but that is just a guess. If the value is unsigned, negative values
(0x8000 and higher) would have to be set to 0 prior to shifting and
clamping. However, that really depends on the chip.

>> +		ret = pmbus_write_word_data(client, page, reg, value);
>> +		break;
>> +
>> +	case PMBUS_IIN_OC_FAULT_LIMIT:
>> +		if (value < SQ24860_IIN_OCF_OFF)
>> +			return -EINVAL;
> 
> [Severity: High]
> Could a negative user limit bypass this bounds check?
> 
> Since value is unsigned, a negative limit (e.g., 0xFFFF) will evaluate
> as greater than SQ24860_IIN_OCF_OFF (165). This bypasses the check below
> and overflows the 32-bit unsigned calculation, effectively disabling
> over-current protection by incorrectly setting the hardware limit to its
> maximum.
> 
Same as above.

> [Severity: Medium]
> Should this clamp the value instead of returning an error?
> 
> The hwmon sysfs ABI convention requires drivers to silently clamp
> out-of-range user limits to the nearest supported hardware value rather
> than returning an error.
> 
> If the requested limit translates to a value below SQ24860_IIN_OCF_OFF,
> returning -EINVAL violates this convention. Would it be better to clamp
> the limit to SQ24860_IIN_OCF_OFF so the underlying register is set to 0?
> 
Yes.

Thanks,
Guenter

>> +		value -= SQ24860_IIN_OCF_OFF;
>> +		value = DIV_ROUND_CLOSEST(((unsigned int)value) * SQ24860_IIN_OCF_DIV,
>> +					  SQ24860_IIN_OCF_NUM);
>> +		value = clamp_val(value, 0, 0x3f);
>> +		ret = pmbus_write_byte_data(client, page, SQ24860_VIREF, value);
>> +		break;
> 

[PATCH v3 3/3] hwmon: Add documentation for SQ24860

[Ziming Zhu]

From: Ziming Zhu <ziming.zhu@silergycorp.com>

Document the supported sysfs attributes for the Silergy SQ24860 PMBus
hwmon driver.

Signed-off-by: Ziming Zhu <ziming.zhu@silergycorp.com>
---
 Documentation/hwmon/index.rst   |  1 +
 Documentation/hwmon/sq24860.rst | 96 +++++++++++++++++++++++++++++++++
 2 files changed, 97 insertions(+)
 create mode 100644 Documentation/hwmon/sq24860.rst

diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index 8b655e5d6b68..6184b88e2095 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -243,6 +243,7 @@ Hardware Monitoring Kernel Drivers
    smsc47m1
    sparx5-temp
    spd5118
+   sq24860
    stpddc60
    surface_fan
    sy7636a-hwmon
diff --git a/Documentation/hwmon/sq24860.rst b/Documentation/hwmon/sq24860.rst
new file mode 100644
index 000000000000..f0182b955d8a
--- /dev/null
+++ b/Documentation/hwmon/sq24860.rst
@@ -0,0 +1,96 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Kernel driver sq24860
+=====================
+
+Supported chips:
+
+  * Silergy SQ24860
+
+    Prefix: 'sq24860'
+
+Author:
+
+	Ziming Zhu <ziming.zhu@silergycorp.com>
+
+Description
+------------
+
+This driver implements support for the Silergy SQ24860 eFuse. The device is an
+integrated circuit protection and power management device with a PMBus
+interface.
+
+The device supports direct format for reading input voltage, output voltage,
+auxiliary voltage, input current, input power, and temperature.
+
+The current and power measurement scale depends on the resistor connected
+between the IMON pin and ground. The resistor value can be configured with the
+``silergy,rimon-micro-ohms`` device tree property. See
+``Documentation/devicetree/bindings/hwmon/pmbus/silergy,sq24860.yaml`` for details.
+
+Due to the specificities of the chip, all history reset attributes are tied
+together. Resetting the history of one sensor resets the history of all sensors.
+
+Sysfs entries
+-------------
+
+The following attributes are supported. Limits are read-write; all other
+attributes are read-only.
+
+======================= ======================================================
+in1_label               "vin"
+in1_input               Measured input voltage.
+in1_average             Average measured input voltage.
+in1_min                 Minimum input voltage limit.
+in1_lcrit               Critical low input voltage limit.
+in1_max                 Maximum input voltage limit.
+in1_crit                Critical high input voltage limit.
+in1_min_alarm           Input voltage low warning alarm.
+in1_lcrit_alarm         Input voltage low fault alarm.
+in1_max_alarm           Input voltage high warning alarm.
+in1_crit_alarm          Input voltage high fault alarm.
+in1_highest             Historical maximum input voltage.
+in1_lowest              Historical minimum input voltage.
+in1_reset_history       Write any value to reset history.
+
+in2_label               "vmon"
+in2_input               Measured auxiliary input voltage.
+
+in3_label               "vout1"
+in3_input               Measured output voltage.
+in3_average             Average measured output voltage.
+in3_min                 Minimum output voltage limit.
+in3_min_alarm           Output voltage low alarm.
+in3_lowest              Historical minimum output voltage.
+in3_reset_history       Write any value to reset history.
+
+curr1_label             "iin"
+curr1_input             Measured input current.
+curr1_average           Average measured input current.
+curr1_max               Maximum input current warning limit.
+curr1_crit              Critical input over-current fault limit.
+curr1_max_alarm         Input current warning alarm.
+curr1_crit_alarm        Input over-current fault alarm.
+curr1_highest           Historical maximum input current.
+curr1_reset_history     Write any value to reset history.
+
+power1_label            "pin"
+power1_input            Measured input power.
+power1_average          Average measured input power.
+power1_max              Maximum input power warning limit.
+power1_alarm            Input power warning alarm.
+power1_input_highest    Historical maximum input power.
+power1_reset_history    Write any value to reset history.
+
+temp1_input             Measured temperature.
+temp1_average           Average measured temperature.
+temp1_max               Maximum temperature warning limit.
+temp1_crit              Critical temperature fault limit.
+temp1_max_alarm         Temperature warning alarm.
+temp1_crit_alarm        Temperature fault alarm.
+temp1_highest           Historical maximum temperature.
+temp1_reset_history     Write any value to reset history.
+
+samples                 Number of samples used for average values.
+======================= ======================================================
+
-- 
2.25.1

Re: [PATCH v3 3/3] hwmon: Add documentation for SQ24860

[sashiko-bot]

> From: Ziming Zhu <ziming.zhu@silergycorp.com>
> 
> Document the supported sysfs attributes for the Silergy SQ24860 PMBus
> hwmon driver.
> 
> Signed-off-by: Ziming Zhu <ziming.zhu@silergycorp.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260611074335.4415-1-zmzhu0630@163.com?part=3