[PATCH v2 0/3] Add support for Silergy SQ24860

[PATCH v2 0/3] Add support for Silergy SQ24860

[Ziming Zhu]

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

Changes in v2:
- Validate silergy,rimon-micro-ohms before programming the current
  calibration gain.
- Avoid underflow when programming PMBUS_IIN_OC_FAULT_LIMIT.
- Replace brittle samples limit calculation with SQ24860_MAX_SAMPLES.
- Update the current/power scaling comment to match the implementation.
- Fix the documented DT property name in sq24860.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                 | 432 ++++++++++++++++++
 6 files changed, 623 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 v2 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

[PATCH v2 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 | 432 ++++++++++++++++++++++++++++++++++
 3 files changed, 452 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..43a2cb542169
--- /dev/null
+++ b/drivers/hwmon/pmbus/sq24860.c
@@ -0,0 +1,432 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Copyright (c) 2024.
+// Author: Ziming Zhu <ziming.zhu@silergycorp.com>
+#include <linux/bitfield.h>
+#include <linux/debugfs.h>
+#include <linux/err.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.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_DEFAULT_GIMON		18180
+
+#define SQ24860_VAUX_DIV		20
+
+static int sq24860_write_iin_cal_gain(struct i2c_client *client, u32 rimon,
+					u32 gimon)
+{
+	u64 temp = (u64)6400 * 1000000000 * 1000;
+	u64 denom;
+	u64 word;
+
+	if (!rimon || !gimon)
+		return -EINVAL;
+
+	denom = (u64)rimon * gimon;
+	word = div_u64(temp, denom);
+	if (word > U16_MAX)
+		return -ERANGE;
+
+	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:
+		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 = SQ24860_DEFAULT_RIMON;
+	u32 gimon = SQ24860_DEFAULT_GIMON;
+	int ret;
+
+	ret = device_property_read_u32(dev, "silergy,rimon-micro-ohms", &rimon);
+	if (ret < 0 && ret != -EINVAL)
+		return dev_err_probe(dev, ret, "failed to get rimon\n");
+
+	ret = sq24860_write_iin_cal_gain(client, rimon, gimon);
+	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

[PATCH v2 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..1888905cd234 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -242,6 +242,7 @@ Hardware Monitoring Kernel Drivers
    smsc47m192
    smsc47m1
    sparx5-temp
+   sq24860
    spd5118
    stpddc60
    surface_fan
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 v2 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/20260605063042.91776-1-zmzhu0630@163.com?part=1

Re: [PATCH v2 3/3] hwmon: Add documentation for SQ24860

[sashiko-bot]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] The 'Hardware Monitoring Kernel Drivers' index list in `Documentation/hwmon/index.rst` is maintained in alphabetical order. The commit incorrectly inserts `sq24860` between `sparx5-temp` and `spd5118`. Alphabetically, 'sq' comes after 'sp', so `sq24860` should be placed after `spd5118` and before `stpddc60`.
--

commit 65caf89dcee60b08d75fdadfaa3541e74096b753
Author: Ziming Zhu <ziming.zhu@silergycorp.com>

hwmon: Add documentation for SQ24860

This commit documents the supported sysfs attributes for the Silergy SQ24860
PMBus hwmon driver.

> diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
> index 8b655e5d6b68b..1888905cd2349 100644
> --- a/Documentation/hwmon/index.rst
> +++ b/Documentation/hwmon/index.rst
> @@ -242,6 +242,7 @@ Hardware Monitoring Kernel Drivers
>     smsc47m192
>     smsc47m1
>     sparx5-temp
> +   sq24860
>     spd5118

[Severity: Low]
This isn't a bug, but the Hardware Monitoring Kernel Drivers index list is
typically maintained in alphabetical order. 

Since sq comes after sp, should sq24860 be placed after spd5118 and before
stpddc60 to maintain this sorting?

>     stpddc60
>     surface_fan

[ ... ]

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260605063042.91776-1-zmzhu0630@163.com?part=3

Re: [PATCH v2 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] Passing a 64-bit divisor to `div_u64()` silently truncates the divisor to 32 bits, causing an incorrect calculation that unconditionally fails probe, and potentially triggering a kernel panic due to division by zero.
- [High] Unsigned underflow when writing a low `PMBUS_IIN_OC_FAULT_LIMIT` value inadvertently configures the maximum hardware over-current limit, defeating hardware protection.
--

commit ba80340cc247f7eb04cd41303e3f6374716421eb
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 input voltage, output voltage, auxiliary voltage,
input current, input power, and temperature.

> diff --git a/drivers/hwmon/pmbus/sq24860.c b/drivers/hwmon/pmbus/sq24860.c
> new file mode 100644
> index 0000000000000..43a2cb542169c
> --- /dev/null
> +++ b/drivers/hwmon/pmbus/sq24860.c

[ ... ]

> +static int sq24860_write_iin_cal_gain(struct i2c_client *client, u32 rimon,
> +					u32 gimon)
> +{
> +	u64 temp = (u64)6400 * 1000000000 * 1000;
> +	u64 denom;
> +	u64 word;
> +
> +	if (!rimon || !gimon)
> +		return -EINVAL;
> +
> +	denom = (u64)rimon * gimon;
> +	word = div_u64(temp, denom);
> +	if (word > U16_MAX)
> +		return -ERANGE;

[Severity: High]
Does this code inadvertently truncate the 64-bit divisor?

Because denom is a 64-bit unsigned integer, passing it to div_u64() which
expects a 32-bit divisor will silently truncate denom to its lower 32 bits.

With the default values (rimon = 1600000000, gimon = 18180), denom evaluates
to 29,088,000,000,000. Truncating this to 32 bits yields 1,044,881,408, causing
the division to incorrectly yield 6,125,096 instead of 220.

Since this exceeds U16_MAX, won't this unconditionally return -ERANGE and
fail the probe? Also, if denom happens to be an exact multiple of 2^32,
could the truncated divisor become 0 and trigger a kernel panic?

Should this use div64_u64() instead?

[ ... ]

> +static int sq24860_write_word_data(struct i2c_client *client,
> +				    int page, int reg, u16 value)
> +{
> +	int ret;
> +
> +	switch (reg) {

[ ... ]

> +	case PMBUS_IIN_OC_FAULT_LIMIT:
> +		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;

[Severity: High]
Will subtracting from value underflow if it is less than 165?

Since value is an unsigned 16-bit integer, if user space requests a
restrictive over-current limit corresponding to a value less than
SQ24860_IIN_OCF_OFF (165), value will underflow and wrap around to a
large positive number.

Because this large value is subsequently clamped to 0x3f (63), won't
attempting to set a restrictive over-current limit inadvertently configure
the hardware to its absolute maximum limit instead?

Could value be checked against SQ24860_IIN_OCF_OFF before the subtraction
to prevent silently defeating the hardware protection?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260605063042.91776-1-zmzhu0630@163.com?part=2