[PATCH v3 0/2] hwmon: Add TSC1641 I2C power monitor driver

[PATCH v3 0/2] hwmon: Add TSC1641 I2C power monitor driver

[Igor Reznichenko]

This patch series adds support for the ST Microelectronics TSC1641
I2C power monitor. The TSC1641 provides bus voltage, current, power,
and temperature measurements via the hwmon subsystem. The driver 
supports optional ALERT pin polarity configuration and exposes the
shunt resistor value and update interval via sysfs.

Tested on Raspberry Pi 3B+ with a TSC1641 evaluation board.

v2: https://lore.kernel.org/linux-hwmon/20251026065057.627276-1-igor@reznichenko.net/

Changes in v3:
- Updated devicetree binding to include optional interrupt property
- Added shunt value clamping
- Changed limit attributes from lcrit/crit to min/max
- Improved limit handling to preserve register content,
  (current limits might not round-trip exactly around extremums due
  to inevitable rounding)
- SATF flag handled properly
- Misc. small fixes

Igor Reznichenko (2):
  dt-bindings: hwmon: ST TSC1641 power monitor
  hwmon: Add TSC1641 I2C power monitor driver

 .../devicetree/bindings/hwmon/st,tsc1641.yaml |  67 ++
 Documentation/hwmon/index.rst                 |   1 +
 Documentation/hwmon/tsc1641.rst               |  87 ++
 drivers/hwmon/Kconfig                         |  12 +
 drivers/hwmon/Makefile                        |   1 +
 drivers/hwmon/tsc1641.c                       | 748 ++++++++++++++++++
 6 files changed, 916 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/st,tsc1641.yaml
 create mode 100644 Documentation/hwmon/tsc1641.rst
 create mode 100644 drivers/hwmon/tsc1641.c

-- 
2.43.0

[PATCH v3 1/2] dt-bindings: hwmon: ST TSC1641 power monitor

[Igor Reznichenko]

Add binding for the TSC1641 I2C power monitor.

Signed-off-by: Igor Reznichenko <igor@reznichenko.net>
---
 .../devicetree/bindings/hwmon/st,tsc1641.yaml | 67 +++++++++++++++++++
 1 file changed, 67 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/st,tsc1641.yaml

diff --git a/Documentation/devicetree/bindings/hwmon/st,tsc1641.yaml b/Documentation/devicetree/bindings/hwmon/st,tsc1641.yaml
new file mode 100644
index 000000000000..cb4e41f0f99e
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/st,tsc1641.yaml
@@ -0,0 +1,67 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/hwmon/st,tsc1641.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: ST Microelectronics TSC1641 I2C power monitor
+
+maintainers:
+  - Igor Reznichenko <igor@reznichenko.net>
+
+description: |
+  TSC1641 is a 60 V, 16-bit high-precision power monitor with I2C and
+  MIPI I3C interface
+
+  Datasheets:
+    https://www.st.com/resource/en/datasheet/tsc1641.pdf
+
+properties:
+  compatible:
+    const: st,tsc1641
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    description: Optional alert interrupt.
+    maxItems: 1
+
+  shunt-resistor-micro-ohms:
+    description: Shunt resistor value in micro-ohms. Since device has internal
+      16-bit RSHUNT register with 10 uOhm LSB, the maximum value is capped at
+      655.35 mOhm.
+    minimum: 100
+    default: 1000
+    maximum: 655350
+
+  st,alert-polarity-active-high:
+    $ref: /schemas/types.yaml#/definitions/flag
+    description: Default value is 0 which configures the normal polarity of the
+      ALERT pin, being active low open-drain. Setting this to 1 configures the
+      polarity of the ALERT pin to be inverted and active high open-drain.
+      Specify this property to set the alert polarity to active-high.
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        power-sensor@40 {
+            compatible = "st,tsc1641";
+            reg = <0x40>;
+            interrupt-parent = <&gpio1>;
+            interrupts = <1 IRQ_TYPE_LEVEL_LOW>; /* Polarity board dependent */
+            shunt-resistor-micro-ohms = <1000>;
+            st,alert-polarity-active-high;
+        };
+    };
-- 
2.43.0

Re: [PATCH v3 1/2] dt-bindings: hwmon: ST TSC1641 power monitor

[Krzysztof Kozlowski]

On Mon, Nov 03, 2025 at 04:33:19PM -0800, Igor Reznichenko wrote:
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/interrupt-controller/irq.h>
> +
> +    i2c {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        power-sensor@40 {
> +            compatible = "st,tsc1641";
> +            reg = <0x40>;
> +            interrupt-parent = <&gpio1>;
> +            interrupts = <1 IRQ_TYPE_LEVEL_LOW>; /* Polarity board dependent */
> +            shunt-resistor-micro-ohms = <1000>;
> +            st,alert-polarity-active-high;

That's wrong IMO. Either you use it as SMBus alert or as CPU interrupt.
If you use as CPU interrupt, then the flag in "interrupts" defines what
is the level of this interrupt. That flag is a combination of both
CPU/SoC side and any inverters on the device. And actually you wrote it
already - "Polarity board dependent" - so why do you:
1. Provide polarity twice
2. Provide inconsistent values - alert interrupt is level low, but
alert interrupt is also active (level) high. So level low or level high?

Best regards,
Krzysztof

Re: [PATCH v3 1/2] dt-bindings: hwmon: ST TSC1641 power monitor

[Igor Reznichenko]

>> +additionalProperties: false
>> +
>> +examples:
>> +  - |
>> +    #include <dt-bindings/interrupt-controller/irq.h>
>> +
>> +    i2c {
>> +        #address-cells = <1>;
>> +        #size-cells = <0>;
>> +
>> +        power-sensor@40 {
>> +            compatible = "st,tsc1641";
>> +            reg = <0x40>;
>> +            interrupt-parent = <&gpio1>;
>> +            interrupts = <1 IRQ_TYPE_LEVEL_LOW>; /* Polarity board dependent */
>> +            shunt-resistor-micro-ohms = <1000>;
>> +            st,alert-polarity-active-high;
>
>That's wrong IMO. Either you use it as SMBus alert or as CPU interrupt.
>If you use as CPU interrupt, then the flag in "interrupts" defines what
>is the level of this interrupt. That flag is a combination of both
>CPU/SoC side and any inverters on the device. And actually you wrote it
>already - "Polarity board dependent" - so why do you:
>1. Provide polarity twice
>2. Provide inconsistent values - alert interrupt is level low, but
>alert interrupt is also active (level) high. So level low or level high?

I tried to illustrate both in one example, but I can see how this is confusing.
Will it work if I split the interrupt part into separate example?

Thanks, Igor

Re: [PATCH v3 1/2] dt-bindings: hwmon: ST TSC1641 power monitor

[Krzysztof Kozlowski]

On 04/11/2025 17:30, Igor Reznichenko wrote:
>>> +additionalProperties: false
>>> +
>>> +examples:
>>> +  - |
>>> +    #include <dt-bindings/interrupt-controller/irq.h>
>>> +
>>> +    i2c {
>>> +        #address-cells = <1>;
>>> +        #size-cells = <0>;
>>> +
>>> +        power-sensor@40 {
>>> +            compatible = "st,tsc1641";
>>> +            reg = <0x40>;
>>> +            interrupt-parent = <&gpio1>;
>>> +            interrupts = <1 IRQ_TYPE_LEVEL_LOW>; /* Polarity board dependent */
>>> +            shunt-resistor-micro-ohms = <1000>;
>>> +            st,alert-polarity-active-high;
>>
>> That's wrong IMO. Either you use it as SMBus alert or as CPU interrupt.
>> If you use as CPU interrupt, then the flag in "interrupts" defines what
>> is the level of this interrupt. That flag is a combination of both
>> CPU/SoC side and any inverters on the device. And actually you wrote it
>> already - "Polarity board dependent" - so why do you:
>> 1. Provide polarity twice
>> 2. Provide inconsistent values - alert interrupt is level low, but
>> alert interrupt is also active (level) high. So level low or level high?
> 
> I tried to illustrate both in one example, but I can see how this is confusing.
> Will it work if I split the interrupt part into separate example?
>

No need for another example, just drop the interrupts here.

Best regards,
Krzysztof

[PATCH v3 2/2] hwmon: Add TSC1641 I2C power monitor driver

[Igor Reznichenko]

Add a driver for the ST Microelectronics TSC1641 16-bit high-precision
power monitor. The driver supports reading bus voltage, current, power,
and temperature. Sysfs attributes are exposed for shunt resistor and
update interval. The driver integrates with the hwmon subsystem and
supports optional ALERT pin polarity configuration.

Signed-off-by: Igor Reznichenko <igor@reznichenko.net>
---
 Documentation/hwmon/index.rst   |   1 +
 Documentation/hwmon/tsc1641.rst |  87 ++++
 drivers/hwmon/Kconfig           |  12 +
 drivers/hwmon/Makefile          |   1 +
 drivers/hwmon/tsc1641.c         | 748 ++++++++++++++++++++++++++++++++
 5 files changed, 849 insertions(+)
 create mode 100644 Documentation/hwmon/tsc1641.rst
 create mode 100644 drivers/hwmon/tsc1641.c

diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index 51a5bdf75b08..4fb9f91f83b3 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -253,6 +253,7 @@ Hardware Monitoring Kernel Drivers
    tps40422
    tps53679
    tps546d24
+   tsc1641
    twl4030-madc-hwmon
    ucd9000
    ucd9200
diff --git a/Documentation/hwmon/tsc1641.rst b/Documentation/hwmon/tsc1641.rst
new file mode 100644
index 000000000000..425e25f7a7d1
--- /dev/null
+++ b/Documentation/hwmon/tsc1641.rst
@@ -0,0 +1,87 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+Kernel driver tsc1641
+=====================
+
+Supported chips:
+
+  * ST TSC1641
+
+    Prefix: 'tsc1641'
+
+    Addresses scanned: -
+
+    Datasheet:
+	https://www.st.com/resource/en/datasheet/tsc1641.pdf
+
+Author:
+	- Igor Reznichenko <igor@reznichenko.net>
+
+
+Description
+-----------
+
+The TSC1641 is a high-precision current, voltage, power, and temperature
+monitoring analog front-end (AFE). It monitors bidirectional current into a
+shunt resistor and load voltage up to 60 V in a synchronized way. Digital bus
+interface is I2C/SMbus. The TSC1641 allows the assertion of several alerts
+regarding the voltage, current, power and temperature.
+
+Usage Notes
+-----------
+
+The TSC1641 driver requires the value of the external shunt resistor to
+correctly compute current and power measurements. The resistor value, in
+micro-ohms, should be provided either through the device tree property
+"shunt-resistor-micro-ohms" or via writable sysfs attribute "shunt_resistor".
+Please refer to the Documentation/devicetree/bindings/hwmon/st,tsc1641.yaml
+for bindings if the device tree is used.
+
+Supported range of shunt resistor values is from 100 uOhm to 655.35 mOhm, in
+10 uOhm steps.
+When selecting the value keep in mind device maximum DC power measurement is
+1600W. See datasheet p.22 for ST recommendations on selecting shunt value.
+
+If the shunt resistor value is not specified in the device tree, the driver
+initializes it to 1000 uOhm by default. Users may configure the correct shunt
+resistor value at runtime by writing to the "shunt_resistor" sysfs attribute.
+
+The driver only supports continuous operating mode.
+Measurement ranges:
+
+================ ===============================================================
+Current          Bidirectional, dependent on shunt
+Bus voltage      0-60V
+Maximum DC power 1600W
+Temperature      -40C to +125C
+================ ===============================================================
+
+Sysfs entries
+-------------
+
+==================== ===========================================================
+in0_input            bus voltage (mV)
+in0_max              bus voltage max alarm limit (mV)
+in0_max_alarm        bus voltage max alarm limit exceeded
+in0_min              bus voltage min alarm limit (mV)
+in0_min_alarm        bus voltage min alarm limit exceeded
+
+curr1_input          current measurement (mA)
+curr1_max            current max alarm limit (mA)
+curr1_max_alarm      current max alarm limit exceeded
+curr1_min            current min alarm limit (mA)
+curr1_min_alarm      current min alarm limit exceeded
+
+power1_input         power measurement (uW)
+power1_max           power max alarm limit (uW)
+power1_max_alarm     power max alarm limit exceeded
+
+shunt_resistor       shunt resistor value (uOhms)
+
+temp1_input          temperature measurement (mdegC)
+temp1_max            temperature max alarm limit (mdegC)
+temp1_max_alarm      temperature max alarm limit exceeded
+
+update_interval      data conversion time (1 - 33ms), longer conversion time
+                     corresponds to higher effective resolution in bits
+==================== ===========================================================
\ No newline at end of file
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 2760feb9f83b..b9d7b02932a6 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -2434,6 +2434,18 @@ config SENSORS_TMP513
 	  This driver can also be built as a module. If so, the module
 	  will be called tmp513.
 
+config SENSORS_TSC1641
+	tristate "ST Microelectronics TSC1641 Power Monitor"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  If you say yes here you get support for TSC1641 power  monitor chip.
+	  The TSC1641 driver is configured for the default configuration of
+	  the part except temperature is enabled by default.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called tsc1641.
+
 config SENSORS_VEXPRESS
 	tristate "Versatile Express"
 	depends on VEXPRESS_CONFIG
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index 73b2abdcc6dd..a8de5bc69f2a 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -233,6 +233,7 @@ obj-$(CONFIG_SENSORS_TMP401)	+= tmp401.o
 obj-$(CONFIG_SENSORS_TMP421)	+= tmp421.o
 obj-$(CONFIG_SENSORS_TMP464)	+= tmp464.o
 obj-$(CONFIG_SENSORS_TMP513)	+= tmp513.o
+obj-$(CONFIG_SENSORS_TSC1641)	+= tsc1641.o
 obj-$(CONFIG_SENSORS_VEXPRESS)	+= vexpress-hwmon.o
 obj-$(CONFIG_SENSORS_VIA_CPUTEMP)+= via-cputemp.o
 obj-$(CONFIG_SENSORS_VIA686A)	+= via686a.o
diff --git a/drivers/hwmon/tsc1641.c b/drivers/hwmon/tsc1641.c
new file mode 100644
index 000000000000..b241206b07ac
--- /dev/null
+++ b/drivers/hwmon/tsc1641.c
@@ -0,0 +1,748 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for ST Microelectronics TSC1641 I2C power monitor
+ *
+ * 60 V, 16-bit high-precision power monitor with I2C and MIPI I3C interface
+ * Datasheet: https://www.st.com/resource/en/datasheet/tsc1641.pdf
+ *
+ * Copyright (C) 2025 Igor Reznichenko <igor@reznichenko.net>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/hwmon.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/sysfs.h>
+#include <linux/util_macros.h>
+
+/* I2C registers */
+#define TSC1641_CONFIG		0x00
+#define TSC1641_SHUNT_VOLTAGE	0x01
+#define TSC1641_LOAD_VOLTAGE	0x02
+#define TSC1641_POWER		0x03
+#define TSC1641_CURRENT		0x04
+#define TSC1641_TEMP		0x05
+#define TSC1641_MASK		0x06
+#define TSC1641_FLAG		0x07
+#define TSC1641_RSHUNT		0x08 /* Shunt resistance */
+#define TSC1641_SOL		0x09
+#define TSC1641_SUL		0x0A
+#define TSC1641_LOL		0x0B
+#define TSC1641_LUL		0x0C
+#define TSC1641_POL		0x0D
+#define TSC1641_TOL		0x0E
+#define TSC1641_MANUF_ID	0xFE /* 0x0006 */
+#define TSC1641_DIE_ID		0xFF /* 0x1000 */
+#define TSC1641_MAX_REG		0xFF
+
+#define TSC1641_RSHUNT_DEFAULT	1000   /* 1mOhm */
+#define TSC1641_CONFIG_DEFAULT	0x003F /* Default mode and temperature sensor */
+#define TSC1641_MASK_DEFAULT	0xFC00 /* Unmask all alerts */
+
+/* Bit mask for conversion time in the configuration register */
+#define TSC1641_CONV_TIME_MASK	GENMASK(7, 4)
+
+#define TSC1641_CONV_TIME_DEFAULT	1024
+#define TSC1641_MIN_UPDATE_INTERVAL	1024
+
+/* LSB value of different registers */
+#define TSC1641_VLOAD_LSB_MVOLT		2
+#define TSC1641_POWER_LSB_UWATT		25000
+#define TSC1641_VSHUNT_LSB_NVOLT	2500 /* Use nanovolts to make it integer */
+#define TSC1641_RSHUNT_LSB_UOHM		10
+#define TSC1641_TEMP_LSB_MDEGC		500
+
+/* Limits based on datasheet */
+#define TSC1641_RSHUNT_MIN_UOHM		100
+#define TSC1641_RSHUNT_MAX_UOHM		655350
+
+#define TSC1641_ALERT_POL_MASK		BIT(1)
+#define TSC1641_ALERT_LATCH_EN_MASK	BIT(0)
+
+/* Flags indicating alerts in TSC1641_FLAG register*/
+#define TSC1641_SAT_FLAG		BIT(13)
+#define TSC1641_SHUNT_OV_FLAG		BIT(6)
+#define TSC1641_SHUNT_UV_FLAG		BIT(5)
+#define TSC1641_LOAD_OV_FLAG		BIT(4)
+#define TSC1641_LOAD_UV_FLAG		BIT(3)
+#define TSC1641_POWER_OVER_FLAG		BIT(2)
+#define TSC1641_TEMP_OVER_FLAG		BIT(1)
+
+static bool tsc1641_writeable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case TSC1641_CONFIG:
+	case TSC1641_MASK:
+	case TSC1641_RSHUNT:
+	case TSC1641_SOL:
+	case TSC1641_SUL:
+	case TSC1641_LOL:
+	case TSC1641_LUL:
+	case TSC1641_POL:
+	case TSC1641_TOL:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool tsc1641_volatile_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case TSC1641_SHUNT_VOLTAGE:
+	case TSC1641_LOAD_VOLTAGE:
+	case TSC1641_POWER:
+	case TSC1641_CURRENT:
+	case TSC1641_TEMP:
+	case TSC1641_FLAG:
+	case TSC1641_MANUF_ID:
+	case TSC1641_DIE_ID:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static const struct regmap_config tsc1641_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 16,
+	.use_single_write = true,
+	.use_single_read = true,
+	.max_register = TSC1641_MAX_REG,
+	.cache_type = REGCACHE_MAPLE,
+	.volatile_reg = tsc1641_volatile_reg,
+	.writeable_reg = tsc1641_writeable_reg,
+};
+
+struct tsc1641_data {
+	long rshunt_uohm;
+	long current_lsb_ua;
+	struct regmap *regmap;
+};
+
+/*
+ * Upper limit due to chip 16-bit shunt register, lower limit to
+ * prevent current and power registers overflow
+ */
+static inline int tsc1641_validate_shunt(u32 val)
+{
+	if (val < TSC1641_RSHUNT_MIN_UOHM || val > TSC1641_RSHUNT_MAX_UOHM)
+		return -EINVAL;
+	return 0;
+}
+
+static int tsc1641_set_shunt(struct tsc1641_data *data, u32 val)
+{
+	struct regmap *regmap = data->regmap;
+	long rshunt_reg;
+
+	if (tsc1641_validate_shunt(val) < 0)
+		return -EINVAL;
+
+	/* RSHUNT register LSB is 10uOhm so need to divide further */
+	rshunt_reg = DIV_ROUND_CLOSEST(val, TSC1641_RSHUNT_LSB_UOHM);
+	/*
+	 * Clamp value to the nearest multiple of TSC1641_RSHUNT_LSB_UOHM
+	 * in case shunt value provided was not a multiple
+	 */
+	data->rshunt_uohm = rshunt_reg * TSC1641_RSHUNT_LSB_UOHM;
+	data->current_lsb_ua = DIV_ROUND_CLOSEST(TSC1641_VSHUNT_LSB_NVOLT * 1000,
+						 data->rshunt_uohm);
+
+	return regmap_write(regmap, TSC1641_RSHUNT, rshunt_reg);
+}
+
+/*
+ * Conversion times in uS, value in CONFIG[CT3:CT0] corresponds to index in this array
+ * See "Table 14. CT3 to CT0: conversion time" in:
+ * https://www.st.com/resource/en/datasheet/tsc1641.pdf
+ */
+static const int tsc1641_conv_times[] = { 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768 };
+
+static int tsc1641_reg_to_upd_interval(u16 config)
+{
+	int idx = FIELD_GET(TSC1641_CONV_TIME_MASK, config);
+
+	idx = clamp_val(idx, 0, ARRAY_SIZE(tsc1641_conv_times) - 1);
+	int conv_time = tsc1641_conv_times[idx];
+
+	/* Don't support sub-millisecond update interval as it's not supported in hwmon */
+	conv_time = max(conv_time, TSC1641_MIN_UPDATE_INTERVAL);
+	/* Return nearest value in milliseconds */
+	return DIV_ROUND_CLOSEST(conv_time, 1000);
+}
+
+static u16 tsc1641_upd_interval_to_reg(long interval)
+{
+	/* Supported interval is 1ms - 33ms */
+	interval = clamp_val(interval, 1, 33);
+
+	int conv = interval * 1000;
+	int conv_bits = find_closest(conv, tsc1641_conv_times,
+				     ARRAY_SIZE(tsc1641_conv_times));
+
+	return FIELD_PREP(TSC1641_CONV_TIME_MASK, conv_bits);
+}
+
+static int tsc1641_chip_write(struct device *dev, u32 attr, long val)
+{
+	struct tsc1641_data *data = dev_get_drvdata(dev);
+
+	switch (attr) {
+	case hwmon_chip_update_interval:
+		return regmap_update_bits(data->regmap, TSC1641_CONFIG,
+					  TSC1641_CONV_TIME_MASK,
+					  tsc1641_upd_interval_to_reg(val));
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static int tsc1641_chip_read(struct device *dev, u32 attr, long *val)
+{
+	struct tsc1641_data *data = dev_get_drvdata(dev);
+	u32 regval;
+	int ret;
+
+	switch (attr) {
+	case hwmon_chip_update_interval:
+		ret = regmap_read(data->regmap, TSC1641_CONFIG, &regval);
+		if (ret)
+			return ret;
+
+		*val = tsc1641_reg_to_upd_interval(regval);
+		return 0;
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static int tsc1641_flag_read(struct regmap *regmap, u32 flag, long *val)
+{
+	unsigned int regval;
+	int ret;
+
+	ret = regmap_read_bypassed(regmap, TSC1641_FLAG, &regval);
+	if (ret)
+		return ret;
+
+	*val = !!(regval & flag);
+	return 0;
+}
+
+static int tsc1641_in_read(struct device *dev, u32 attr, long *val)
+{
+	struct tsc1641_data *data = dev_get_drvdata(dev);
+	struct regmap *regmap = data->regmap;
+	unsigned int regval;
+	int ret, reg;
+	long sat_flag;
+
+	switch (attr) {
+	case hwmon_in_input:
+		reg = TSC1641_LOAD_VOLTAGE;
+		break;
+	case hwmon_in_min:
+		reg = TSC1641_LUL;
+		break;
+	case hwmon_in_max:
+		reg = TSC1641_LOL;
+		break;
+	case hwmon_in_min_alarm:
+		return tsc1641_flag_read(regmap, TSC1641_LOAD_UV_FLAG, val);
+	case hwmon_in_max_alarm:
+		return tsc1641_flag_read(regmap, TSC1641_LOAD_OV_FLAG, val);
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	ret = regmap_read(regmap, reg, &regval);
+	if (ret)
+		return ret;
+
+	/* Check if load voltage is out of range */
+	if (reg == TSC1641_LOAD_VOLTAGE) {
+		/* Register is 15-bit max */
+		if (regval & 0x8000)
+			return -ENODATA;
+
+		ret  = tsc1641_flag_read(regmap, TSC1641_SAT_FLAG, &sat_flag);
+		if (ret)
+			return ret;
+		/* Out of range conditions per datasheet */
+		if (sat_flag && (regval == 0x7FFF || !regval))
+			return -ENODATA;
+	}
+
+	*val = regval * TSC1641_VLOAD_LSB_MVOLT;
+	return 0;
+}
+
+/* Chip supports bidirectional (positive or negative) current */
+static int tsc1641_curr_read(struct device *dev, u32 attr, long *val)
+{
+	struct tsc1641_data *data = dev_get_drvdata(dev);
+	struct regmap *regmap = data->regmap;
+	int regval;
+	int ret, reg;
+	long sat_flag;
+
+	/* Current limits are the shunt under/over voltage limits */
+	switch (attr) {
+	case hwmon_curr_input:
+		reg = TSC1641_CURRENT;
+		break;
+	case hwmon_curr_min:
+		reg = TSC1641_SUL;
+		break;
+	case hwmon_curr_max:
+		reg = TSC1641_SOL;
+		break;
+	case hwmon_curr_min_alarm:
+		return tsc1641_flag_read(regmap, TSC1641_SHUNT_UV_FLAG, val);
+	case hwmon_curr_max_alarm:
+		return tsc1641_flag_read(regmap, TSC1641_SHUNT_OV_FLAG, val);
+	default:
+		return -EOPNOTSUPP;
+	}
+	/*
+	 * Current uses shunt voltage, so check if it's out of range.
+	 * We report current register in sysfs to stay consistent with internal
+	 * power calculations which use current register values
+	 */
+	if (reg == TSC1641_CURRENT) {
+		ret = regmap_read(regmap, TSC1641_SHUNT_VOLTAGE, &regval);
+		if (ret)
+			return ret;
+
+		ret = tsc1641_flag_read(regmap, TSC1641_SAT_FLAG, &sat_flag);
+		if (ret)
+			return ret;
+
+		if (sat_flag && (regval == 0x7FFF || regval == 0x8000))
+			return -ENODATA;
+	}
+
+	ret = regmap_read(regmap, reg, &regval);
+	if (ret)
+		return ret;
+
+	/* Current in milliamps, signed */
+	*val = DIV_ROUND_CLOSEST((s16)regval * data->current_lsb_ua, 1000);
+	return 0;
+}
+
+static int tsc1641_power_read(struct device *dev, u32 attr, long *val)
+{
+	struct tsc1641_data *data = dev_get_drvdata(dev);
+	struct regmap *regmap = data->regmap;
+	unsigned int regval;
+	int ret, reg;
+
+	switch (attr) {
+	case hwmon_power_input:
+		reg = TSC1641_POWER;
+		break;
+	case hwmon_power_max:
+		reg = TSC1641_POL;
+		break;
+	case hwmon_power_max_alarm:
+		return tsc1641_flag_read(regmap, TSC1641_POWER_OVER_FLAG, val);
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	ret = regmap_read(regmap, reg, &regval);
+	if (ret)
+		return ret;
+
+	*val = regval * TSC1641_POWER_LSB_UWATT;
+	return 0;
+}
+
+static int tsc1641_temp_read(struct device *dev, u32 attr, long *val)
+{
+	struct tsc1641_data *data = dev_get_drvdata(dev);
+	struct regmap *regmap = data->regmap;
+	unsigned int regval;
+	int ret, reg;
+
+	switch (attr) {
+	case hwmon_temp_input:
+		reg = TSC1641_TEMP;
+		break;
+	case hwmon_temp_max:
+		reg = TSC1641_TOL;
+		break;
+	case hwmon_temp_max_alarm:
+		return tsc1641_flag_read(regmap, TSC1641_TEMP_OVER_FLAG, val);
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	ret = regmap_read(regmap, reg, &regval);
+	if (ret)
+		return ret;
+
+	/* 0x8000 means that TEMP measurement not enabled */
+	if (reg == TSC1641_TEMP && regval == 0x8000)
+		return -ENODATA;
+
+	/* Both temperature and limit registers are signed */
+	*val = (s16)regval * TSC1641_TEMP_LSB_MDEGC;
+	return 0;
+}
+
+static int tsc1641_in_write(struct device *dev, u32 attr, long val)
+{
+	struct tsc1641_data *data = dev_get_drvdata(dev);
+	struct regmap *regmap = data->regmap;
+	unsigned int regval;
+	int reg;
+
+	switch (attr) {
+	case hwmon_in_min:
+		reg = TSC1641_LUL;
+		break;
+	case hwmon_in_max:
+		reg = TSC1641_LOL;
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+	/* Clamp to full register range */
+	val = clamp_val(val, 0, TSC1641_VLOAD_LSB_MVOLT * USHRT_MAX);
+	regval = DIV_ROUND_CLOSEST(val, TSC1641_VLOAD_LSB_MVOLT);
+
+	return regmap_write(regmap, reg, regval);
+}
+
+static int tsc1641_curr_write(struct device *dev, u32 attr, long val)
+{
+	struct tsc1641_data *data = dev_get_drvdata(dev);
+	struct regmap *regmap = data->regmap;
+	int reg, regval;
+
+	switch (attr) {
+	case hwmon_curr_min:
+		reg = TSC1641_SUL;
+		break;
+	case hwmon_curr_max:
+		reg = TSC1641_SOL;
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	/* Should never happen if init was ok */
+	if (WARN_ON_ONCE(!data->current_lsb_ua))
+		return -EINVAL;
+
+	/* Convert val in milliamps to register */
+	regval = DIV_ROUND_CLOSEST(val * 1000, data->current_lsb_ua);
+	/*
+	 * Prevent signed 16-bit overflow.
+	 * Integer arithmetic and shunt scaling can quantize values near 0x7FFF/0x8000,
+	 * so reading and writing back may not preserve the exact original register value.
+	 */
+	regval = clamp_val(regval, SHRT_MIN, SHRT_MAX);
+	/* SUL and SOL registers are signed */
+	return regmap_write(regmap, reg, regval & 0xFFFF);
+}
+
+static int tsc1641_power_write(struct device *dev, u32 attr, long val)
+{
+	struct tsc1641_data *data = dev_get_drvdata(dev);
+	struct regmap *regmap = data->regmap;
+	unsigned int regval;
+
+	switch (attr) {
+	case hwmon_power_max:
+		/* Clamp to full register range */
+		val = clamp_val(val, 0, TSC1641_POWER_LSB_UWATT * USHRT_MAX);
+		regval = DIV_ROUND_CLOSEST(val, TSC1641_POWER_LSB_UWATT);
+		return regmap_write(regmap, TSC1641_POL, regval);
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static int tsc1641_temp_write(struct device *dev, u32 attr, long val)
+{
+	struct tsc1641_data *data = dev_get_drvdata(dev);
+	struct regmap *regmap = data->regmap;
+	int regval;
+
+	switch (attr) {
+	case hwmon_temp_max:
+		/* Clamp to full register range */
+		val = clamp_val(val, TSC1641_TEMP_LSB_MDEGC * SHRT_MIN,
+				TSC1641_TEMP_LSB_MDEGC * SHRT_MAX);
+		regval = DIV_ROUND_CLOSEST(val, TSC1641_TEMP_LSB_MDEGC);
+		/* TOL register is signed */
+		return regmap_write(regmap, TSC1641_TOL, regval & 0xFFFF);
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static umode_t tsc1641_is_visible(const void *data, enum hwmon_sensor_types type,
+				  u32 attr, int channel)
+{
+	switch (type) {
+	case hwmon_chip:
+		switch (attr) {
+		case hwmon_chip_update_interval:
+			return 0644;
+		default:
+			break;
+		}
+		break;
+	case hwmon_in:
+		switch (attr) {
+		case hwmon_in_input:
+			return 0444;
+		case hwmon_in_min:
+		case hwmon_in_max:
+			return 0644;
+		case hwmon_in_min_alarm:
+		case hwmon_in_max_alarm:
+			return 0444;
+		default:
+			break;
+		}
+		break;
+	case hwmon_curr:
+		switch (attr) {
+		case hwmon_curr_input:
+			return 0444;
+		case hwmon_curr_min:
+		case hwmon_curr_max:
+			return 0644;
+		case hwmon_curr_min_alarm:
+		case hwmon_curr_max_alarm:
+			return 0444;
+		default:
+			break;
+		}
+		break;
+	case hwmon_power:
+		switch (attr) {
+		case hwmon_power_input:
+			return 0444;
+		case hwmon_power_max:
+			return 0644;
+		case hwmon_power_max_alarm:
+			return 0444;
+		default:
+			break;
+		}
+		break;
+	case hwmon_temp:
+		switch (attr) {
+		case hwmon_temp_input:
+			return 0444;
+		case hwmon_temp_max:
+			return 0644;
+		case hwmon_temp_max_alarm:
+			return 0444;
+		default:
+			break;
+		}
+		break;
+	default:
+		break;
+	}
+	return 0;
+}
+
+static int tsc1641_read(struct device *dev, enum hwmon_sensor_types type,
+			u32 attr, int channel, long *val)
+{
+	switch (type) {
+	case hwmon_chip:
+		return tsc1641_chip_read(dev, attr, val);
+	case hwmon_in:
+		return tsc1641_in_read(dev, attr, val);
+	case hwmon_curr:
+		return tsc1641_curr_read(dev, attr, val);
+	case hwmon_power:
+		return tsc1641_power_read(dev, attr, val);
+	case hwmon_temp:
+		return tsc1641_temp_read(dev, attr, val);
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static int tsc1641_write(struct device *dev, enum hwmon_sensor_types type,
+			 u32 attr, int channel, long val)
+{
+	switch (type) {
+	case hwmon_chip:
+		return tsc1641_chip_write(dev, attr, val);
+	case hwmon_in:
+		return tsc1641_in_write(dev, attr, val);
+	case hwmon_curr:
+		return tsc1641_curr_write(dev, attr, val);
+	case hwmon_power:
+		return tsc1641_power_write(dev, attr, val);
+	case hwmon_temp:
+		return tsc1641_temp_write(dev, attr, val);
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static const struct hwmon_channel_info * const tsc1641_info[] = {
+	HWMON_CHANNEL_INFO(chip,
+			   HWMON_C_UPDATE_INTERVAL),
+	HWMON_CHANNEL_INFO(in,
+			   HWMON_I_INPUT | HWMON_I_MAX | HWMON_I_MAX_ALARM |
+			   HWMON_I_MIN | HWMON_I_MIN_ALARM),
+	HWMON_CHANNEL_INFO(curr,
+			   HWMON_C_INPUT | HWMON_C_MAX | HWMON_C_MAX_ALARM |
+			   HWMON_C_MIN | HWMON_C_MIN_ALARM),
+	HWMON_CHANNEL_INFO(power,
+			   HWMON_P_INPUT | HWMON_P_MAX | HWMON_P_MAX_ALARM),
+	HWMON_CHANNEL_INFO(temp,
+			   HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_MAX_ALARM),
+	NULL
+};
+
+static ssize_t shunt_resistor_show(struct device *dev,
+				   struct device_attribute *da, char *buf)
+{
+	struct tsc1641_data *data = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%li\n", data->rshunt_uohm);
+}
+
+static ssize_t shunt_resistor_store(struct device *dev,
+				    struct device_attribute *da,
+				    const char *buf, size_t count)
+{
+	struct tsc1641_data *data = dev_get_drvdata(dev);
+	unsigned int val;
+	int ret;
+
+	ret = kstrtouint(buf, 10, &val);
+	if (ret < 0)
+		return ret;
+
+	ret = tsc1641_set_shunt(data, val);
+	if (ret < 0)
+		return ret;
+	return count;
+}
+
+static const struct hwmon_ops tsc1641_hwmon_ops = {
+	.is_visible = tsc1641_is_visible,
+	.read = tsc1641_read,
+	.write = tsc1641_write,
+};
+
+static const struct hwmon_chip_info tsc1641_chip_info = {
+	.ops = &tsc1641_hwmon_ops,
+	.info = tsc1641_info,
+};
+
+static DEVICE_ATTR_RW(shunt_resistor);
+
+/* Shunt resistor value is exposed via sysfs attribute */
+static struct attribute *tsc1641_attrs[] = {
+	&dev_attr_shunt_resistor.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(tsc1641);
+
+static int tsc1641_init(struct device *dev, struct tsc1641_data *data)
+{
+	struct regmap *regmap = data->regmap;
+	bool active_high;
+	u32 shunt;
+	int ret;
+
+	if (device_property_read_u32(dev, "shunt-resistor-micro-ohms", &shunt) < 0)
+		shunt = TSC1641_RSHUNT_DEFAULT;
+
+	if (tsc1641_validate_shunt(shunt) < 0) {
+		dev_err(dev, "invalid shunt resistor value %u\n", shunt);
+		return -EINVAL;
+	}
+
+	ret = tsc1641_set_shunt(data, shunt);
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_write(regmap, TSC1641_CONFIG, TSC1641_CONFIG_DEFAULT);
+	if (ret < 0)
+		return ret;
+
+	active_high = device_property_read_bool(dev, "st,alert-polarity-active-high");
+
+	return regmap_write(regmap, TSC1641_MASK, TSC1641_MASK_DEFAULT |
+			    FIELD_PREP(TSC1641_ALERT_POL_MASK, active_high));
+}
+
+static int tsc1641_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct tsc1641_data *data;
+	struct device *hwmon_dev;
+	int ret;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->regmap = devm_regmap_init_i2c(client, &tsc1641_regmap_config);
+	if (IS_ERR(data->regmap))
+		return dev_err_probe(dev, PTR_ERR(data->regmap),
+				     "failed to allocate register map\n");
+
+	ret = tsc1641_init(dev, data);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "failed to configure device\n");
+
+	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
+							 data, &tsc1641_chip_info, tsc1641_groups);
+	if (IS_ERR(hwmon_dev))
+		return PTR_ERR(hwmon_dev);
+
+	dev_info(dev, "power monitor %s (Rshunt = %li uOhm)\n",
+		 client->name, data->rshunt_uohm);
+
+	return 0;
+}
+
+static const struct i2c_device_id tsc1641_id[] = {
+	{ "tsc1641", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, tsc1641_id);
+
+static const struct of_device_id __maybe_unused tsc1641_of_match[] = {
+	{ .compatible = "st,tsc1641" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, tsc1641_of_match);
+
+static struct i2c_driver tsc1641_driver = {
+	.driver = {
+		.name = "tsc1641",
+		.of_match_table = of_match_ptr(tsc1641_of_match),
+	},
+	.probe = tsc1641_probe,
+	.id_table = tsc1641_id,
+};
+
+module_i2c_driver(tsc1641_driver);
+
+MODULE_AUTHOR("Igor Reznichenko <igor@reznichenko.net>");
+MODULE_DESCRIPTION("tsc1641 driver");
+MODULE_LICENSE("GPL");
-- 
2.43.0

Re: [PATCH v3 2/2] hwmon: Add TSC1641 I2C power monitor driver

[Guenter Roeck]

On 11/3/25 16:33, Igor Reznichenko wrote:
> Add a driver for the ST Microelectronics TSC1641 16-bit high-precision
> power monitor. The driver supports reading bus voltage, current, power,
> and temperature. Sysfs attributes are exposed for shunt resistor and
> update interval. The driver integrates with the hwmon subsystem and
> supports optional ALERT pin polarity configuration.
> 
> Signed-off-by: Igor Reznichenko <igor@reznichenko.net>
> ---
>   Documentation/hwmon/index.rst   |   1 +
>   Documentation/hwmon/tsc1641.rst |  87 ++++
>   drivers/hwmon/Kconfig           |  12 +
>   drivers/hwmon/Makefile          |   1 +
>   drivers/hwmon/tsc1641.c         | 748 ++++++++++++++++++++++++++++++++
>   5 files changed, 849 insertions(+)
>   create mode 100644 Documentation/hwmon/tsc1641.rst
>   create mode 100644 drivers/hwmon/tsc1641.c
> 
> diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
> index 51a5bdf75b08..4fb9f91f83b3 100644
> --- a/Documentation/hwmon/index.rst
> +++ b/Documentation/hwmon/index.rst
> @@ -253,6 +253,7 @@ Hardware Monitoring Kernel Drivers
>      tps40422
>      tps53679
>      tps546d24
> +   tsc1641
>      twl4030-madc-hwmon
>      ucd9000
>      ucd9200
> diff --git a/Documentation/hwmon/tsc1641.rst b/Documentation/hwmon/tsc1641.rst
> new file mode 100644
> index 000000000000..425e25f7a7d1
> --- /dev/null
> +++ b/Documentation/hwmon/tsc1641.rst
> @@ -0,0 +1,87 @@
> +.. SPDX-License-Identifier: GPL-2.0-only
> +
> +Kernel driver tsc1641
> +=====================
> +
> +Supported chips:
> +
> +  * ST TSC1641
> +
> +    Prefix: 'tsc1641'
> +
> +    Addresses scanned: -
> +
> +    Datasheet:
> +	https://www.st.com/resource/en/datasheet/tsc1641.pdf
> +
> +Author:
> +	- Igor Reznichenko <igor@reznichenko.net>
> +
> +
> +Description
> +-----------
> +
> +The TSC1641 is a high-precision current, voltage, power, and temperature
> +monitoring analog front-end (AFE). It monitors bidirectional current into a
> +shunt resistor and load voltage up to 60 V in a synchronized way. Digital bus
> +interface is I2C/SMbus. The TSC1641 allows the assertion of several alerts
> +regarding the voltage, current, power and temperature.
> +
> +Usage Notes
> +-----------
> +
> +The TSC1641 driver requires the value of the external shunt resistor to
> +correctly compute current and power measurements. The resistor value, in
> +micro-ohms, should be provided either through the device tree property
> +"shunt-resistor-micro-ohms" or via writable sysfs attribute "shunt_resistor".
> +Please refer to the Documentation/devicetree/bindings/hwmon/st,tsc1641.yaml
> +for bindings if the device tree is used.
> +
> +Supported range of shunt resistor values is from 100 uOhm to 655.35 mOhm, in
> +10 uOhm steps.
> +When selecting the value keep in mind device maximum DC power measurement is
> +1600W. See datasheet p.22 for ST recommendations on selecting shunt value.
> +
> +If the shunt resistor value is not specified in the device tree, the driver
> +initializes it to 1000 uOhm by default. Users may configure the correct shunt
> +resistor value at runtime by writing to the "shunt_resistor" sysfs attribute.
> +
> +The driver only supports continuous operating mode.
> +Measurement ranges:
> +
> +================ ===============================================================
> +Current          Bidirectional, dependent on shunt
> +Bus voltage      0-60V
> +Maximum DC power 1600W
> +Temperature      -40C to +125C
> +================ ===============================================================
> +
> +Sysfs entries
> +-------------
> +
> +==================== ===========================================================
> +in0_input            bus voltage (mV)
> +in0_max              bus voltage max alarm limit (mV)
> +in0_max_alarm        bus voltage max alarm limit exceeded
> +in0_min              bus voltage min alarm limit (mV)
> +in0_min_alarm        bus voltage min alarm limit exceeded
> +
> +curr1_input          current measurement (mA)
> +curr1_max            current max alarm limit (mA)
> +curr1_max_alarm      current max alarm limit exceeded
> +curr1_min            current min alarm limit (mA)
> +curr1_min_alarm      current min alarm limit exceeded
> +
> +power1_input         power measurement (uW)
> +power1_max           power max alarm limit (uW)
> +power1_max_alarm     power max alarm limit exceeded
> +
> +shunt_resistor       shunt resistor value (uOhms)
> +
> +temp1_input          temperature measurement (mdegC)
> +temp1_max            temperature max alarm limit (mdegC)
> +temp1_max_alarm      temperature max alarm limit exceeded
> +
> +update_interval      data conversion time (1 - 33ms), longer conversion time
> +                     corresponds to higher effective resolution in bits
> +==================== ===========================================================
> \ No newline at end of file
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index 2760feb9f83b..b9d7b02932a6 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -2434,6 +2434,18 @@ config SENSORS_TMP513
>   	  This driver can also be built as a module. If so, the module
>   	  will be called tmp513.
>   
> +config SENSORS_TSC1641
> +	tristate "ST Microelectronics TSC1641 Power Monitor"
> +	depends on I2C
> +	select REGMAP_I2C
> +	help
> +	  If you say yes here you get support for TSC1641 power  monitor chip.
> +	  The TSC1641 driver is configured for the default configuration of
> +	  the part except temperature is enabled by default.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called tsc1641.
> +
>   config SENSORS_VEXPRESS
>   	tristate "Versatile Express"
>   	depends on VEXPRESS_CONFIG
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index 73b2abdcc6dd..a8de5bc69f2a 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -233,6 +233,7 @@ obj-$(CONFIG_SENSORS_TMP401)	+= tmp401.o
>   obj-$(CONFIG_SENSORS_TMP421)	+= tmp421.o
>   obj-$(CONFIG_SENSORS_TMP464)	+= tmp464.o
>   obj-$(CONFIG_SENSORS_TMP513)	+= tmp513.o
> +obj-$(CONFIG_SENSORS_TSC1641)	+= tsc1641.o
>   obj-$(CONFIG_SENSORS_VEXPRESS)	+= vexpress-hwmon.o
>   obj-$(CONFIG_SENSORS_VIA_CPUTEMP)+= via-cputemp.o
>   obj-$(CONFIG_SENSORS_VIA686A)	+= via686a.o
> diff --git a/drivers/hwmon/tsc1641.c b/drivers/hwmon/tsc1641.c
> new file mode 100644
> index 000000000000..b241206b07ac
> --- /dev/null
> +++ b/drivers/hwmon/tsc1641.c
> @@ -0,0 +1,748 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Driver for ST Microelectronics TSC1641 I2C power monitor
> + *
> + * 60 V, 16-bit high-precision power monitor with I2C and MIPI I3C interface
> + * Datasheet: https://www.st.com/resource/en/datasheet/tsc1641.pdf
> + *
> + * Copyright (C) 2025 Igor Reznichenko <igor@reznichenko.net>
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/bits.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/hwmon.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +#include <linux/sysfs.h>
> +#include <linux/util_macros.h>
> +
> +/* I2C registers */
> +#define TSC1641_CONFIG		0x00
> +#define TSC1641_SHUNT_VOLTAGE	0x01
> +#define TSC1641_LOAD_VOLTAGE	0x02
> +#define TSC1641_POWER		0x03
> +#define TSC1641_CURRENT		0x04
> +#define TSC1641_TEMP		0x05
> +#define TSC1641_MASK		0x06
> +#define TSC1641_FLAG		0x07
> +#define TSC1641_RSHUNT		0x08 /* Shunt resistance */
> +#define TSC1641_SOL		0x09
> +#define TSC1641_SUL		0x0A
> +#define TSC1641_LOL		0x0B
> +#define TSC1641_LUL		0x0C
> +#define TSC1641_POL		0x0D
> +#define TSC1641_TOL		0x0E
> +#define TSC1641_MANUF_ID	0xFE /* 0x0006 */
> +#define TSC1641_DIE_ID		0xFF /* 0x1000 */
> +#define TSC1641_MAX_REG		0xFF
> +
> +#define TSC1641_RSHUNT_DEFAULT	1000   /* 1mOhm */
> +#define TSC1641_CONFIG_DEFAULT	0x003F /* Default mode and temperature sensor */
> +#define TSC1641_MASK_DEFAULT	0xFC00 /* Unmask all alerts */
> +
> +/* Bit mask for conversion time in the configuration register */
> +#define TSC1641_CONV_TIME_MASK	GENMASK(7, 4)
> +
> +#define TSC1641_CONV_TIME_DEFAULT	1024
> +#define TSC1641_MIN_UPDATE_INTERVAL	1024
> +
> +/* LSB value of different registers */
> +#define TSC1641_VLOAD_LSB_MVOLT		2
> +#define TSC1641_POWER_LSB_UWATT		25000
> +#define TSC1641_VSHUNT_LSB_NVOLT	2500 /* Use nanovolts to make it integer */
> +#define TSC1641_RSHUNT_LSB_UOHM		10
> +#define TSC1641_TEMP_LSB_MDEGC		500
> +
> +/* Limits based on datasheet */
> +#define TSC1641_RSHUNT_MIN_UOHM		100
> +#define TSC1641_RSHUNT_MAX_UOHM		655350
> +
> +#define TSC1641_ALERT_POL_MASK		BIT(1)
> +#define TSC1641_ALERT_LATCH_EN_MASK	BIT(0)
> +
> +/* Flags indicating alerts in TSC1641_FLAG register*/
> +#define TSC1641_SAT_FLAG		BIT(13)
> +#define TSC1641_SHUNT_OV_FLAG		BIT(6)
> +#define TSC1641_SHUNT_UV_FLAG		BIT(5)
> +#define TSC1641_LOAD_OV_FLAG		BIT(4)
> +#define TSC1641_LOAD_UV_FLAG		BIT(3)
> +#define TSC1641_POWER_OVER_FLAG		BIT(2)
> +#define TSC1641_TEMP_OVER_FLAG		BIT(1)
> +
> +static bool tsc1641_writeable_reg(struct device *dev, unsigned int reg)
> +{
> +	switch (reg) {
> +	case TSC1641_CONFIG:
> +	case TSC1641_MASK:
> +	case TSC1641_RSHUNT:
> +	case TSC1641_SOL:
> +	case TSC1641_SUL:
> +	case TSC1641_LOL:
> +	case TSC1641_LUL:
> +	case TSC1641_POL:
> +	case TSC1641_TOL:
> +		return true;
> +	default:
> +		return false;
> +	}
> +}
> +
> +static bool tsc1641_volatile_reg(struct device *dev, unsigned int reg)
> +{
> +	switch (reg) {
> +	case TSC1641_SHUNT_VOLTAGE:
> +	case TSC1641_LOAD_VOLTAGE:
> +	case TSC1641_POWER:
> +	case TSC1641_CURRENT:
> +	case TSC1641_TEMP:
> +	case TSC1641_FLAG:
> +	case TSC1641_MANUF_ID:
> +	case TSC1641_DIE_ID:
> +		return true;
> +	default:
> +		return false;
> +	}
> +}
> +
> +static const struct regmap_config tsc1641_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 16,
> +	.use_single_write = true,
> +	.use_single_read = true,
> +	.max_register = TSC1641_MAX_REG,
> +	.cache_type = REGCACHE_MAPLE,
> +	.volatile_reg = tsc1641_volatile_reg,
> +	.writeable_reg = tsc1641_writeable_reg,
> +};
> +
> +struct tsc1641_data {
> +	long rshunt_uohm;
> +	long current_lsb_ua;
> +	struct regmap *regmap;
> +};
> +
> +/*
> + * Upper limit due to chip 16-bit shunt register, lower limit to
> + * prevent current and power registers overflow
> + */
> +static inline int tsc1641_validate_shunt(u32 val)
> +{
> +	if (val < TSC1641_RSHUNT_MIN_UOHM || val > TSC1641_RSHUNT_MAX_UOHM)
> +		return -EINVAL;
> +	return 0;
> +}
> +
> +static int tsc1641_set_shunt(struct tsc1641_data *data, u32 val)
> +{
> +	struct regmap *regmap = data->regmap;
> +	long rshunt_reg;
> +
> +	if (tsc1641_validate_shunt(val) < 0)
> +		return -EINVAL;
> +

This is validated twice if called from tsc1641_init().

Here:
	TSC1641_RSHUNT_MIN_UOHM <= val <= TSC1641_RSHUNT_MAX_UOHM

> +	/* RSHUNT register LSB is 10uOhm so need to divide further */
> +	rshunt_reg = DIV_ROUND_CLOSEST(val, TSC1641_RSHUNT_LSB_UOHM);

	rshunt_reg >= (TSC1641_RSHUNT_MIN_UOHM / TSC1641_RSHUNT_LSB_UOHM)
		   >= 10
		   <= (TSC1641_RSHUNT_MAX_UOHM / TSC1641_RSHUNT_LSB_UOHM)
		   <= 655350 / 10 == 65535

> +	/*
> +	 * Clamp value to the nearest multiple of TSC1641_RSHUNT_LSB_UOHM
> +	 * in case shunt value provided was not a multiple
> +	 */
> +	data->rshunt_uohm = rshunt_reg * TSC1641_RSHUNT_LSB_UOHM;

	rshunt_reg >= 10 * TSC1641_RSHUNT_LSB_UOHM
		   >= 10 * 10 == 100
		   <= 65535 * 10 == 655350

> +	data->current_lsb_ua = DIV_ROUND_CLOSEST(TSC1641_VSHUNT_LSB_NVOLT * 1000,
> +						 data->rshunt_uohm);

	current_lsb_us >= TSC1641_VSHUNT_LSB_NVOLT * 1000 / 655350
		       >= 2500 * 1000 / 655350
		       >= 3.81 ~= 4

So current_lsb_us will never be 0, and the WARN_ONCE above is unnecessary.

If you don't trust the calculations (or they are wrong ;-), add

	if (!data->current_lsb_ua)
		return -EINVAL;

but please drop the WARN_ONCE() above.

> +
> +	return regmap_write(regmap, TSC1641_RSHUNT, rshunt_reg);
> +}
> +
> +/*
> + * Conversion times in uS, value in CONFIG[CT3:CT0] corresponds to index in this array
> + * See "Table 14. CT3 to CT0: conversion time" in:
> + * https://www.st.com/resource/en/datasheet/tsc1641.pdf
> + */
> +static const int tsc1641_conv_times[] = { 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768 };
> +
> +static int tsc1641_reg_to_upd_interval(u16 config)
> +{
> +	int idx = FIELD_GET(TSC1641_CONV_TIME_MASK, config);
> +
> +	idx = clamp_val(idx, 0, ARRAY_SIZE(tsc1641_conv_times) - 1);
> +	int conv_time = tsc1641_conv_times[idx];
> +
> +	/* Don't support sub-millisecond update interval as it's not supported in hwmon */
> +	conv_time = max(conv_time, TSC1641_MIN_UPDATE_INTERVAL);
> +	/* Return nearest value in milliseconds */
> +	return DIV_ROUND_CLOSEST(conv_time, 1000);
> +}
> +
> +static u16 tsc1641_upd_interval_to_reg(long interval)
> +{
> +	/* Supported interval is 1ms - 33ms */
> +	interval = clamp_val(interval, 1, 33);
> +
> +	int conv = interval * 1000;
> +	int conv_bits = find_closest(conv, tsc1641_conv_times,
> +				     ARRAY_SIZE(tsc1641_conv_times));
> +
> +	return FIELD_PREP(TSC1641_CONV_TIME_MASK, conv_bits);
> +}
> +
> +static int tsc1641_chip_write(struct device *dev, u32 attr, long val)
> +{
> +	struct tsc1641_data *data = dev_get_drvdata(dev);
> +
> +	switch (attr) {
> +	case hwmon_chip_update_interval:
> +		return regmap_update_bits(data->regmap, TSC1641_CONFIG,
> +					  TSC1641_CONV_TIME_MASK,
> +					  tsc1641_upd_interval_to_reg(val));
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static int tsc1641_chip_read(struct device *dev, u32 attr, long *val)
> +{
> +	struct tsc1641_data *data = dev_get_drvdata(dev);
> +	u32 regval;
> +	int ret;
> +
> +	switch (attr) {
> +	case hwmon_chip_update_interval:
> +		ret = regmap_read(data->regmap, TSC1641_CONFIG, &regval);
> +		if (ret)
> +			return ret;
> +
> +		*val = tsc1641_reg_to_upd_interval(regval);
> +		return 0;
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static int tsc1641_flag_read(struct regmap *regmap, u32 flag, long *val)
> +{
> +	unsigned int regval;
> +	int ret;
> +
> +	ret = regmap_read_bypassed(regmap, TSC1641_FLAG, &regval);
> +	if (ret)
> +		return ret;
> +
> +	*val = !!(regval & flag);
> +	return 0;
> +}
> +
> +static int tsc1641_in_read(struct device *dev, u32 attr, long *val)
> +{
> +	struct tsc1641_data *data = dev_get_drvdata(dev);
> +	struct regmap *regmap = data->regmap;
> +	unsigned int regval;
> +	int ret, reg;
> +	long sat_flag;
> +
> +	switch (attr) {
> +	case hwmon_in_input:
> +		reg = TSC1641_LOAD_VOLTAGE;
> +		break;
> +	case hwmon_in_min:
> +		reg = TSC1641_LUL;
> +		break;
> +	case hwmon_in_max:
> +		reg = TSC1641_LOL;
> +		break;
> +	case hwmon_in_min_alarm:
> +		return tsc1641_flag_read(regmap, TSC1641_LOAD_UV_FLAG, val);
> +	case hwmon_in_max_alarm:
> +		return tsc1641_flag_read(regmap, TSC1641_LOAD_OV_FLAG, val);
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	ret = regmap_read(regmap, reg, &regval);
> +	if (ret)
> +		return ret;
> +
> +	/* Check if load voltage is out of range */
> +	if (reg == TSC1641_LOAD_VOLTAGE) {
> +		/* Register is 15-bit max */
> +		if (regval & 0x8000)
> +			return -ENODATA;
> +
> +		ret  = tsc1641_flag_read(regmap, TSC1641_SAT_FLAG, &sat_flag);
> +		if (ret)
> +			return ret;
> +		/* Out of range conditions per datasheet */
> +		if (sat_flag && (regval == 0x7FFF || !regval))
> +			return -ENODATA;
> +	}
> +
> +	*val = regval * TSC1641_VLOAD_LSB_MVOLT;
> +	return 0;
> +}
> +
> +/* Chip supports bidirectional (positive or negative) current */
> +static int tsc1641_curr_read(struct device *dev, u32 attr, long *val)
> +{
> +	struct tsc1641_data *data = dev_get_drvdata(dev);
> +	struct regmap *regmap = data->regmap;
> +	int regval;
> +	int ret, reg;
> +	long sat_flag;
> +
> +	/* Current limits are the shunt under/over voltage limits */
> +	switch (attr) {
> +	case hwmon_curr_input:
> +		reg = TSC1641_CURRENT;
> +		break;
> +	case hwmon_curr_min:
> +		reg = TSC1641_SUL;
> +		break;
> +	case hwmon_curr_max:
> +		reg = TSC1641_SOL;
> +		break;
> +	case hwmon_curr_min_alarm:
> +		return tsc1641_flag_read(regmap, TSC1641_SHUNT_UV_FLAG, val);
> +	case hwmon_curr_max_alarm:
> +		return tsc1641_flag_read(regmap, TSC1641_SHUNT_OV_FLAG, val);
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +	/*
> +	 * Current uses shunt voltage, so check if it's out of range.
> +	 * We report current register in sysfs to stay consistent with internal
> +	 * power calculations which use current register values
> +	 */
> +	if (reg == TSC1641_CURRENT) {
> +		ret = regmap_read(regmap, TSC1641_SHUNT_VOLTAGE, &regval);
> +		if (ret)
> +			return ret;
> +
> +		ret = tsc1641_flag_read(regmap, TSC1641_SAT_FLAG, &sat_flag);
> +		if (ret)
> +			return ret;
> +
> +		if (sat_flag && (regval == 0x7FFF || regval == 0x8000))
> +			return -ENODATA;
> +	}
> +
> +	ret = regmap_read(regmap, reg, &regval);
> +	if (ret)
> +		return ret;
> +
> +	/* Current in milliamps, signed */
> +	*val = DIV_ROUND_CLOSEST((s16)regval * data->current_lsb_ua, 1000);
> +	return 0;
> +}
> +
> +static int tsc1641_power_read(struct device *dev, u32 attr, long *val)
> +{
> +	struct tsc1641_data *data = dev_get_drvdata(dev);
> +	struct regmap *regmap = data->regmap;
> +	unsigned int regval;
> +	int ret, reg;
> +
> +	switch (attr) {
> +	case hwmon_power_input:
> +		reg = TSC1641_POWER;
> +		break;
> +	case hwmon_power_max:
> +		reg = TSC1641_POL;
> +		break;
> +	case hwmon_power_max_alarm:
> +		return tsc1641_flag_read(regmap, TSC1641_POWER_OVER_FLAG, val);
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	ret = regmap_read(regmap, reg, &regval);
> +	if (ret)
> +		return ret;
> +
> +	*val = regval * TSC1641_POWER_LSB_UWATT;
> +	return 0;
> +}
> +
> +static int tsc1641_temp_read(struct device *dev, u32 attr, long *val)
> +{
> +	struct tsc1641_data *data = dev_get_drvdata(dev);
> +	struct regmap *regmap = data->regmap;
> +	unsigned int regval;
> +	int ret, reg;
> +
> +	switch (attr) {
> +	case hwmon_temp_input:
> +		reg = TSC1641_TEMP;
> +		break;
> +	case hwmon_temp_max:
> +		reg = TSC1641_TOL;
> +		break;
> +	case hwmon_temp_max_alarm:
> +		return tsc1641_flag_read(regmap, TSC1641_TEMP_OVER_FLAG, val);
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	ret = regmap_read(regmap, reg, &regval);
> +	if (ret)
> +		return ret;
> +
> +	/* 0x8000 means that TEMP measurement not enabled */
> +	if (reg == TSC1641_TEMP && regval == 0x8000)
> +		return -ENODATA;
> +
> +	/* Both temperature and limit registers are signed */
> +	*val = (s16)regval * TSC1641_TEMP_LSB_MDEGC;
> +	return 0;
> +}
> +
> +static int tsc1641_in_write(struct device *dev, u32 attr, long val)
> +{
> +	struct tsc1641_data *data = dev_get_drvdata(dev);
> +	struct regmap *regmap = data->regmap;
> +	unsigned int regval;
> +	int reg;
> +
> +	switch (attr) {
> +	case hwmon_in_min:
> +		reg = TSC1641_LUL;
> +		break;
> +	case hwmon_in_max:
> +		reg = TSC1641_LOL;
> +		break;
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +	/* Clamp to full register range */
> +	val = clamp_val(val, 0, TSC1641_VLOAD_LSB_MVOLT * USHRT_MAX);
> +	regval = DIV_ROUND_CLOSEST(val, TSC1641_VLOAD_LSB_MVOLT);
> +
> +	return regmap_write(regmap, reg, regval);
> +}
> +
> +static int tsc1641_curr_write(struct device *dev, u32 attr, long val)
> +{
> +	struct tsc1641_data *data = dev_get_drvdata(dev);
> +	struct regmap *regmap = data->regmap;
> +	int reg, regval;
> +
> +	switch (attr) {
> +	case hwmon_curr_min:
> +		reg = TSC1641_SUL;
> +		break;
> +	case hwmon_curr_max:
> +		reg = TSC1641_SOL;
> +		break;
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	/* Should never happen if init was ok */
> +	if (WARN_ON_ONCE(!data->current_lsb_ua))
> +		return -EINVAL;
> +

The code should make sure that this never happens, making this check
unnecessary. Also see above.

> +	/* Convert val in milliamps to register */
> +	regval = DIV_ROUND_CLOSEST(val * 1000, data->current_lsb_ua);

curr1_min: Suspected underflow: [min=-81920, read 0, written -9223372036854775808]
curr1_max: Suspected underflow: [min=-81920, read 0, written -9223372036854775808]

You'll need to clamp 'val' first before multiplying it.


> +	/*
> +	 * Prevent signed 16-bit overflow.
> +	 * Integer arithmetic and shunt scaling can quantize values near 0x7FFF/0x8000,
> +	 * so reading and writing back may not preserve the exact original register value.
> +	 */
> +	regval = clamp_val(regval, SHRT_MIN, SHRT_MAX);
> +	/* SUL and SOL registers are signed */
> +	return regmap_write(regmap, reg, regval & 0xFFFF);
> +}
> +
> +static int tsc1641_power_write(struct device *dev, u32 attr, long val)
> +{
> +	struct tsc1641_data *data = dev_get_drvdata(dev);
> +	struct regmap *regmap = data->regmap;
> +	unsigned int regval;
> +
> +	switch (attr) {
> +	case hwmon_power_max:
> +		/* Clamp to full register range */
> +		val = clamp_val(val, 0, TSC1641_POWER_LSB_UWATT * USHRT_MAX);
> +		regval = DIV_ROUND_CLOSEST(val, TSC1641_POWER_LSB_UWATT);
> +		return regmap_write(regmap, TSC1641_POL, regval);
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static int tsc1641_temp_write(struct device *dev, u32 attr, long val)
> +{
> +	struct tsc1641_data *data = dev_get_drvdata(dev);
> +	struct regmap *regmap = data->regmap;
> +	int regval;
> +
> +	switch (attr) {
> +	case hwmon_temp_max:
> +		/* Clamp to full register range */
> +		val = clamp_val(val, TSC1641_TEMP_LSB_MDEGC * SHRT_MIN,
> +				TSC1641_TEMP_LSB_MDEGC * SHRT_MAX);
> +		regval = DIV_ROUND_CLOSEST(val, TSC1641_TEMP_LSB_MDEGC);
> +		/* TOL register is signed */
> +		return regmap_write(regmap, TSC1641_TOL, regval & 0xFFFF);
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static umode_t tsc1641_is_visible(const void *data, enum hwmon_sensor_types type,
> +				  u32 attr, int channel)
> +{
> +	switch (type) {
> +	case hwmon_chip:
> +		switch (attr) {
> +		case hwmon_chip_update_interval:
> +			return 0644;
> +		default:
> +			break;
> +		}
> +		break;
> +	case hwmon_in:
> +		switch (attr) {
> +		case hwmon_in_input:
> +			return 0444;
> +		case hwmon_in_min:
> +		case hwmon_in_max:
> +			return 0644;
> +		case hwmon_in_min_alarm:
> +		case hwmon_in_max_alarm:
> +			return 0444;
> +		default:
> +			break;
> +		}
> +		break;
> +	case hwmon_curr:
> +		switch (attr) {
> +		case hwmon_curr_input:
> +			return 0444;
> +		case hwmon_curr_min:
> +		case hwmon_curr_max:
> +			return 0644;
> +		case hwmon_curr_min_alarm:
> +		case hwmon_curr_max_alarm:
> +			return 0444;
> +		default:
> +			break;
> +		}
> +		break;
> +	case hwmon_power:
> +		switch (attr) {
> +		case hwmon_power_input:
> +			return 0444;
> +		case hwmon_power_max:
> +			return 0644;
> +		case hwmon_power_max_alarm:
> +			return 0444;
> +		default:
> +			break;
> +		}
> +		break;
> +	case hwmon_temp:
> +		switch (attr) {
> +		case hwmon_temp_input:
> +			return 0444;
> +		case hwmon_temp_max:
> +			return 0644;
> +		case hwmon_temp_max_alarm:
> +			return 0444;
> +		default:
> +			break;
> +		}
> +		break;
> +	default:
> +		break;
> +	}
> +	return 0;
> +}
> +
> +static int tsc1641_read(struct device *dev, enum hwmon_sensor_types type,
> +			u32 attr, int channel, long *val)
> +{
> +	switch (type) {
> +	case hwmon_chip:
> +		return tsc1641_chip_read(dev, attr, val);
> +	case hwmon_in:
> +		return tsc1641_in_read(dev, attr, val);
> +	case hwmon_curr:
> +		return tsc1641_curr_read(dev, attr, val);
> +	case hwmon_power:
> +		return tsc1641_power_read(dev, attr, val);
> +	case hwmon_temp:
> +		return tsc1641_temp_read(dev, attr, val);
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static int tsc1641_write(struct device *dev, enum hwmon_sensor_types type,
> +			 u32 attr, int channel, long val)
> +{
> +	switch (type) {
> +	case hwmon_chip:
> +		return tsc1641_chip_write(dev, attr, val);
> +	case hwmon_in:
> +		return tsc1641_in_write(dev, attr, val);
> +	case hwmon_curr:
> +		return tsc1641_curr_write(dev, attr, val);
> +	case hwmon_power:
> +		return tsc1641_power_write(dev, attr, val);
> +	case hwmon_temp:
> +		return tsc1641_temp_write(dev, attr, val);
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static const struct hwmon_channel_info * const tsc1641_info[] = {
> +	HWMON_CHANNEL_INFO(chip,
> +			   HWMON_C_UPDATE_INTERVAL),
> +	HWMON_CHANNEL_INFO(in,
> +			   HWMON_I_INPUT | HWMON_I_MAX | HWMON_I_MAX_ALARM |
> +			   HWMON_I_MIN | HWMON_I_MIN_ALARM),
> +	HWMON_CHANNEL_INFO(curr,
> +			   HWMON_C_INPUT | HWMON_C_MAX | HWMON_C_MAX_ALARM |
> +			   HWMON_C_MIN | HWMON_C_MIN_ALARM),
> +	HWMON_CHANNEL_INFO(power,
> +			   HWMON_P_INPUT | HWMON_P_MAX | HWMON_P_MAX_ALARM),
> +	HWMON_CHANNEL_INFO(temp,
> +			   HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_MAX_ALARM),
> +	NULL
> +};
> +
> +static ssize_t shunt_resistor_show(struct device *dev,
> +				   struct device_attribute *da, char *buf)
> +{
> +	struct tsc1641_data *data = dev_get_drvdata(dev);
> +
> +	return sysfs_emit(buf, "%li\n", data->rshunt_uohm);
> +}
> +
> +static ssize_t shunt_resistor_store(struct device *dev,
> +				    struct device_attribute *da,
> +				    const char *buf, size_t count)
> +{
> +	struct tsc1641_data *data = dev_get_drvdata(dev);
> +	unsigned int val;
> +	int ret;
> +
> +	ret = kstrtouint(buf, 10, &val);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = tsc1641_set_shunt(data, val);
> +	if (ret < 0)
> +		return ret;
> +	return count;
> +}
> +
> +static const struct hwmon_ops tsc1641_hwmon_ops = {
> +	.is_visible = tsc1641_is_visible,
> +	.read = tsc1641_read,
> +	.write = tsc1641_write,
> +};
> +
> +static const struct hwmon_chip_info tsc1641_chip_info = {
> +	.ops = &tsc1641_hwmon_ops,
> +	.info = tsc1641_info,
> +};
> +
> +static DEVICE_ATTR_RW(shunt_resistor);
> +
> +/* Shunt resistor value is exposed via sysfs attribute */
> +static struct attribute *tsc1641_attrs[] = {
> +	&dev_attr_shunt_resistor.attr,
> +	NULL,
> +};
> +ATTRIBUTE_GROUPS(tsc1641);
> +
> +static int tsc1641_init(struct device *dev, struct tsc1641_data *data)
> +{
> +	struct regmap *regmap = data->regmap;
> +	bool active_high;
> +	u32 shunt;
> +	int ret;
> +
> +	if (device_property_read_u32(dev, "shunt-resistor-micro-ohms", &shunt) < 0)
> +		shunt = TSC1641_RSHUNT_DEFAULT;
> +
> +	if (tsc1641_validate_shunt(shunt) < 0) {
> +		dev_err(dev, "invalid shunt resistor value %u\n", shunt);
> +		return -EINVAL;
> +	}
> +
> +	ret = tsc1641_set_shunt(data, shunt);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_write(regmap, TSC1641_CONFIG, TSC1641_CONFIG_DEFAULT);
> +	if (ret < 0)
> +		return ret;
> +
> +	active_high = device_property_read_bool(dev, "st,alert-polarity-active-high");
> +
> +	return regmap_write(regmap, TSC1641_MASK, TSC1641_MASK_DEFAULT |
> +			    FIELD_PREP(TSC1641_ALERT_POL_MASK, active_high));
> +}
> +
> +static int tsc1641_probe(struct i2c_client *client)
> +{
> +	struct device *dev = &client->dev;
> +	struct tsc1641_data *data;
> +	struct device *hwmon_dev;
> +	int ret;
> +
> +	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	data->regmap = devm_regmap_init_i2c(client, &tsc1641_regmap_config);
> +	if (IS_ERR(data->regmap))
> +		return dev_err_probe(dev, PTR_ERR(data->regmap),
> +				     "failed to allocate register map\n");
> +
> +	ret = tsc1641_init(dev, data);
> +	if (ret < 0)
> +		return dev_err_probe(dev, ret, "failed to configure device\n");
> +
> +	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name,
> +							 data, &tsc1641_chip_info, tsc1641_groups);
> +	if (IS_ERR(hwmon_dev))
> +		return PTR_ERR(hwmon_dev);
> +
> +	dev_info(dev, "power monitor %s (Rshunt = %li uOhm)\n",
> +		 client->name, data->rshunt_uohm);
> +
> +	return 0;
> +}
> +
> +static const struct i2c_device_id tsc1641_id[] = {
> +	{ "tsc1641", 0 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, tsc1641_id);
> +
> +static const struct of_device_id __maybe_unused tsc1641_of_match[] = {
> +	{ .compatible = "st,tsc1641" },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, tsc1641_of_match);
> +
> +static struct i2c_driver tsc1641_driver = {
> +	.driver = {
> +		.name = "tsc1641",
> +		.of_match_table = of_match_ptr(tsc1641_of_match),
> +	},
> +	.probe = tsc1641_probe,
> +	.id_table = tsc1641_id,
> +};
> +
> +module_i2c_driver(tsc1641_driver);
> +
> +MODULE_AUTHOR("Igor Reznichenko <igor@reznichenko.net>");
> +MODULE_DESCRIPTION("tsc1641 driver");
> +MODULE_LICENSE("GPL");