Re: [PATCH v2 3/3] hwmon: Driver for Texas Instruments INA238

From: Guenter Roeck
Date: Wed Oct 27 2021 - 11:57:04 EST

On 10/27/21 12:42 AM, Nathan Rossi wrote:
From: Nathan Rossi <nathan.rossi@xxxxxxxx>

The INA238 is a I2C power monitor similar to other INA2xx devices,
providing shunt voltage, bus voltage, current, power and temperature
measurements.

Signed-off-by: Nathan Rossi <nathan.rossi@xxxxxxxx>
---
Changes in v2:
- Add ina238 documentation to hwmon/index
- Remove unused header includes and sort
- Set regmap_config max_register in struct initialization
- Remove shunt-resistor attribute and associated functions
- Rename crit/lcrit attributes to max/min
- Rework to use the hwmon_chip_info API
- Add max_alarm and min_alarm channels and associated alert/alarm config
- Add device tree ti,shunt-gain property use and ADCRANGE setup
---
Documentation/hwmon/ina238.rst | 56 ++++
Documentation/hwmon/index.rst | 1 +
drivers/hwmon/Kconfig | 12 +
drivers/hwmon/Makefile | 1 +
drivers/hwmon/ina238.c | 672 +++++++++++++++++++++++++++++++++++++++++
5 files changed, 742 insertions(+)
create mode 100644 Documentation/hwmon/ina238.rst
create mode 100644 drivers/hwmon/ina238.c

diff --git a/Documentation/hwmon/ina238.rst b/Documentation/hwmon/ina238.rst
new file mode 100644
index 0000000000..d9f4799844
--- /dev/null
+++ b/Documentation/hwmon/ina238.rst
@@ -0,0 +1,56 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+Kernel driver ina238
+====================
+
+Supported chips:
+
+ * Texas Instruments INA238
+
+ Prefix: 'ina238'
+
+ Addresses: I2C 0x40 - 0x4f
+
+ Datasheet:
+ https://www.ti.com/lit/gpn/ina238
+
+Author: Nathan Rossi <nathan.rossi@xxxxxxxx>
+
+Description
+-----------
+
+The INA238 is a current shunt, power and temperature monitor with an I2C
+interface. It includes a number of programmable functions including alerts,
+conversion rate, sample averaging and selectable shunt voltage accuracy.
+
+The shunt value in micro-ohms can be set via platform data or device tree at
+compile-time or via the shunt_resistor attribute in sysfs at run-time. Please
+refer to the Documentation/devicetree/bindings/hwmon/ti,ina2xx.yaml for bindings
+if the device tree is used.
+
+Sysfs entries
+-------------
+
+======================= =======================================================
+in0_input Shunt voltage (mV)
+in0_min Minimum shunt voltage threshold (mV)
+in0_min_alarm Minimum shunt voltage alarm
+in0_max Maximum shunt voltage threshold (mV)
+in0_max_alarm Maximum shunt voltage alarm
+
+in1_input Bus voltage (mV)
+in1_min Minimum bus voltage threshold (mV)
+in1_min_alarm Minimum shunt voltage alarm
+in1_max Maximum bus voltage threshold (mV)
+in1_max_alarm Maximum shunt voltage alarm
+
+power1_input Power measurement (uW)
+power1_max Maximum power threshold (uW)
+power1_max_alarm Maximum power alarm
+
+curr1_input Current measurement (mA)
+
+temp1_input Die temperature measurement (mC)
+temp1_max Maximum die temperature threshold (mC)
+temp1_max_alarm Maximum die temperature alarm
+======================= =======================================================
diff --git a/Documentation/hwmon/index.rst b/Documentation/hwmon/index.rst
index 7046bf1870..6f30c8c9c7 100644
--- a/Documentation/hwmon/index.rst
+++ b/Documentation/hwmon/index.rst
@@ -76,6 +76,7 @@ Hardware Monitoring Kernel Drivers
ibmpowernv
ina209
ina2xx
+ ina238
ina3221
intel-m10-bmc-hwmon
ir35221
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 7fde4c6e1e..21aff4cef7 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -1872,6 +1872,18 @@ config SENSORS_INA2XX
This driver can also be built as a module. If so, the module
will be called ina2xx.
+config SENSORS_INA238
+ tristate "Texas Instruments INA238"
+ depends on I2C
+ select REGMAP_I2C
+ help
+ If you say yes here you get support for the INA238 power monitor
+ chip. This driver supports voltage, current, power and temperature
+ measurements as well as alarm configuration.
+
+ This driver can also be built as a module. If so, the module
+ will be called ina238.
+
config SENSORS_INA3221
tristate "Texas Instruments INA3221 Triple Power Monitor"
depends on I2C
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index baee6a8d4d..1ddb26f57a 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -90,6 +90,7 @@ obj-$(CONFIG_SENSORS_IBMPOWERNV)+= ibmpowernv.o
obj-$(CONFIG_SENSORS_IIO_HWMON) += iio_hwmon.o
obj-$(CONFIG_SENSORS_INA209) += ina209.o
obj-$(CONFIG_SENSORS_INA2XX) += ina2xx.o
+obj-$(CONFIG_SENSORS_INA238) += ina238.o
obj-$(CONFIG_SENSORS_INA3221) += ina3221.o
obj-$(CONFIG_SENSORS_INTEL_M10_BMC_HWMON) += intel-m10-bmc-hwmon.o
obj-$(CONFIG_SENSORS_IT87) += it87.o
diff --git a/drivers/hwmon/ina238.c b/drivers/hwmon/ina238.c
new file mode 100644
index 0000000000..f9d031bdfe
--- /dev/null
+++ b/drivers/hwmon/ina238.c
@@ -0,0 +1,672 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Driver for Texas Instruments INA238 power monitor chip
+ * Datasheet: https://www.ti.com/product/ina238
+ *
+ * Copyright (C) 2021 Nathan Rossi <nathan.rossi@xxxxxxxx>
+ */
+
+#include <linux/err.h>
+#include <linux/hwmon-sysfs.h>

Unnecessary.

+#include <linux/hwmon.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+
+#include <linux/platform_data/ina2xx.h>
+
+/* INA238 register definitions */
+#define INA238_CONFIG 0x0
+#define INA238_ADC_CONFIG 0x1
+#define INA238_SHUNT_CALIBRATION 0x2
+#define INA238_SHUNT_VOLTAGE 0x4
+#define INA238_BUS_VOLTAGE 0x5
+#define INA238_DIE_TEMP 0x6
+#define INA238_CURRENT 0x7
+#define INA238_POWER 0x8
+#define INA238_DIAG_ALERT 0xb
+#define INA238_SHUNT_OVER_VOLTAGE 0xc
+#define INA238_SHUNT_UNDER_VOLTAGE 0xd
+#define INA238_BUS_OVER_VOLTAGE 0xe
+#define INA238_BUS_UNDER_VOLTAGE 0xf
+#define INA238_TEMP_LIMIT 0x10
+#define INA238_POWER_LIMIT 0x11
+#define INA238_DEVICE_ID 0x3f
+
+#define INA238_CONFIG_ADCRANGE BIT(4)
+
+#define INA238_DIAG_ALERT_TMPOL BIT(7)
+#define INA238_DIAG_ALERT_SHNTOL BIT(6)
+#define INA238_DIAG_ALERT_SHNTUL BIT(5)
+#define INA238_DIAG_ALERT_BUSOL BIT(4)
+#define INA238_DIAG_ALERT_BUSUL BIT(3)
+#define INA238_DIAG_ALERT_POL BIT(2)
+
+#define INA238_REGISTERS 0x11
+
+#define INA238_RSHUNT_DEFAULT 10000 /* uOhm */
+
+/* Default configuration of device on reset. */
+#define INA238_CONFIG_DEFAULT 0
+/* 16 sample averaging, 1052us conversion time, continuous mode */
+#define INA238_ADC_CONFIG_DEFAULT 0xfb6a
+/* Configure alerts to be based on averaged value (SLOWALERT) */
+#define INA238_DIAG_ALERT_DEFAULT 0x2000
+/*
+ * This driver uses a fixed calibration value in order to scale current/power
+ * based on a fixed shunt resistor value. This allows for conversion within the
+ * device to avoid integer limits whilst current/power accuracy is scaled
+ * relative to the shunt resistor value within the driver. This is similar to
+ * how the ina2xx driver handles current/power scaling.
+ *
+ * The end result of this is that increasing shunt values (from a fixed 20 mOhm
+ * shunt) increase the effective current/power accuracy whilst limiting the
+ * range and decreasing shunt values decrease the effective accuracy but
+ * increase the range.
+ *
+ * The value of the Current register is calculated given the following:
+ * Current (A) = (shunt voltage register * 5) * calibration / 81920
+ *
+ * The maximum shunt voltage is 163.835 mV (0x7fff, ADC_RANGE = 0, gain = 4).
+ * With the maximum current value of 0x7fff and a fixed shunt value results in
+ * a calibration value of 16384 (0x4000).
+ *
+ * 0x7fff = (0x7fff * 5) * calibration / 81920
+ * calibration = 0x4000
+ *
+ * Equivalent calibration is applied for the Power register (maximum value for
+ * bus voltage is 102396.875 mV, 0x7fff), where the maximum power that can
+ * occur is ~16776192 uW (register value 0x147a8):
+ *
+ * This scaling means the resulting values for Current and Power registers need
+ * to be scaled by the difference between the fixed shunt resistor and the
+ * actual shunt resistor:
+ *
+ * shunt = 0x4000 / (819.2 * 10^6) / 0.001 = 20000 uOhms (with 1mA/lsb)
+ *
+ * Current (mA) = register value * 20000 / rshunt / 4 * gain
+ * Power (W) = 0.2 * register value * 20000 / rshunt / 4 * gain
+ */
+#define INA238_CALIBRATION_VALUE 16384
+#define INA238_FIXED_SHUNT 20000
+
+#define INA238_SHUNT_VOLTAGE_LSB 5 /* 5 uV/lsb */
+#define INA238_BUS_VOLTAGE_LSB 3125 /* 3.125 mV/lsb */
+#define INA238_DIE_TEMP_LSB 125 /* 125 mC/lsb */
+
+static struct regmap_config ina238_regmap_config = {
+ .max_register = INA238_REGISTERS,
+ .reg_bits = 8,
+ .val_bits = 16,
+};
+
+struct ina238_data {
+ struct i2c_client *client;
+ struct mutex config_lock;
+ struct regmap *regmap;
+ u32 rshunt;
+ u32 gain;
+};
+
+static int ina238_read_reg24(const struct i2c_client *client, u8 reg, u32 *val)
+{
+ u8 data[3];
+ int err;
+
+ /* 24-bit register read */
+ err = i2c_smbus_read_i2c_block_data(client, reg, 3, data);
+ if (err != 3)
+ return err;

i2c_smbus_read_i2c_block_data() can return 1 or 2, which should be reported as error.
You need something like

if (err < 0)
return err;
if (err != 3)
return -EIO;

+ *val = (data[0] << 16) | (data[1] << 8) | data[2];
+
+ return 0;
+}
+
+static int ina238_read_in(struct device *dev, u32 attr, int channel,
+ long *val)
+{
+ struct ina238_data *data = dev_get_drvdata(dev);
+ int reg, mask;
+ int regval;
+ int err;
+
+ switch (channel) {
+ case 0:
+ switch (attr) {
+ case hwmon_in_input:
+ reg = INA238_SHUNT_VOLTAGE;
+ break;
+ case hwmon_in_max:
+ reg = INA238_SHUNT_OVER_VOLTAGE;
+ break;
+ case hwmon_in_min:
+ reg = INA238_SHUNT_UNDER_VOLTAGE;
+ break;
+ case hwmon_in_max_alarm:
+ reg = INA238_DIAG_ALERT;
+ mask = INA238_DIAG_ALERT_SHNTOL;
+ break;
+ case hwmon_in_min_alarm:
+ reg = INA238_DIAG_ALERT;
+ mask = INA238_DIAG_ALERT_SHNTUL;
+ break;
+ default:
+ return -EOPNOTSUPP;
+ }
+ break;
+ case 1:
+ switch (attr) {
+ case hwmon_in_input:
+ reg = INA238_BUS_VOLTAGE;
+ break;
+ case hwmon_in_max:
+ reg = INA238_BUS_OVER_VOLTAGE;
+ break;
+ case hwmon_in_min:
+ reg = INA238_BUS_UNDER_VOLTAGE;
+ break;
+ case hwmon_in_max_alarm:
+ reg = INA238_DIAG_ALERT;
+ mask = INA238_DIAG_ALERT_BUSOL;
+ break;
+ case hwmon_in_min_alarm:
+ reg = INA238_DIAG_ALERT;
+ mask = INA238_DIAG_ALERT_BUSUL;
+ break;
+ default:
+ return -EOPNOTSUPP;
+ }
+ break;
+ default:
+ return -EOPNOTSUPP;
+ }
+
+ err = regmap_read(data->regmap, reg, &regval);
+ if (err < 0)
+ return err;
+
+ switch (attr) {
+ case hwmon_in_input:
+ case hwmon_in_max:
+ case hwmon_in_min:
+ /* signed register, value in mV */
+ if (channel == 0)
+ /* gain of 1 -> LSB / 4 */
+ *val = div_s64((s16)regval * INA238_SHUNT_VOLTAGE_LSB,
+ 1000 * (4 - data->gain + 1));
+ else
+ *val = div_s64((s16)regval * INA238_BUS_VOLTAGE_LSB,
+ 1000);

Pleae check the use of 64-bit divide operations. The above operations
never overflow a long, not even a 32-bit long, and div_s64() is therefore
unencessary. I am quite sure the same applies to current read operations,
though I didn't check.

+ break;
+ case hwmon_in_max_alarm:
+ case hwmon_in_min_alarm:
+ *val = regval & mask ? 1 : 0;

*val = !!(regval & mask);

+ break;
+ }
+
+ return 0;
+}
+
+static int ina238_write_in(struct device *dev, u32 attr, int channel,
+ long val)
+{
+ struct ina238_data *data = dev_get_drvdata(dev);
+ int regval;
+
+ if (attr != hwmon_in_max && attr != hwmon_in_min)
+ return -EOPNOTSUPP;
+
+ /* convert decimal to register value */
+ switch (channel) {
+ case 0:
+ /* signed */
+ regval = div_s64((s64)val * 1000LL * (4 - data->gain + 1),
+ INA238_SHUNT_VOLTAGE_LSB);

I am quite sure the typecast is unnecessary here. Also, if you'd use clamp_val()
prior to the multiply/divide operation, I am quite sure you would not need
to use 64-bit divide operations.

+ if (regval > S16_MAX || regval < S16_MIN)
+ return -EINVAL;

We usually handle limit writes out of range with clamp_val() and
do not expect users to find the valid range for a given chip.

regval = clamp_val(regval, S16_MIN, S16_MAX);

+
+ switch (attr) {
+ case hwmon_in_max:
+ return regmap_write(data->regmap,
+ INA238_SHUNT_OVER_VOLTAGE, regval);
+ case hwmon_in_min:
+ return regmap_write(data->regmap,
+ INA238_SHUNT_UNDER_VOLTAGE, regval);
+ default:
+ return -EOPNOTSUPP;
+ }
+ case 1:
+ regval = div_u64((u64)val * 1000ULL, INA238_BUS_VOLTAGE_LSB);

This converts -1 to a really large value, which then overflows before being divided.
The result is more or less random. I think you'll need to use clamp_val first here.

+ if (regval > U16_MAX || regval < 0)
+ return -EINVAL;

regval = clamp_val(regval, 0, U16_MAX);

+
+ switch (attr) {
+ case hwmon_in_max:
+ return regmap_write(data->regmap,
+ INA238_BUS_OVER_VOLTAGE, regval);
+ case hwmon_in_min:
+ return regmap_write(data->regmap,
+ INA238_BUS_UNDER_VOLTAGE, regval);
+ default:
+ return -EOPNOTSUPP;
+ }
+ default:
+ return -EOPNOTSUPP;
+ }
+}
+
+static int ina238_read_current(struct device *dev, u32 attr, int channel,
+ long *val)
+{
+ struct ina238_data *data = dev_get_drvdata(dev);
+ int regval;
+ int err;
+
+ if (channel != 0)
+ return -EOPNOTSUPP;
+
+ switch (attr) {
+ case hwmon_curr_input:
+ err = regmap_read(data->regmap, INA238_CURRENT, &regval);
+ if (err < 0)
+ return err;
+
+ /* Signed register, fixed 1mA current lsb. result in mA */
+ *val = div_s64((s16)regval * INA238_FIXED_SHUNT * data->gain,
+ data->rshunt * 4);
+ break;
+ default:
+ return -EOPNOTSUPP;
+ }
+
+ return 0;
+}
+
+static int ina238_read_power(struct device *dev, u32 attr, int channel,
+ long *val)
+{
+ struct ina238_data *data = dev_get_drvdata(dev);
+ long long power;
+ int regval;
+ int err;
+
+ if (channel != 0)
+ return -EOPNOTSUPP;
+
+ switch (attr) {
+ case hwmon_power_input:
+ err = ina238_read_reg24(data->client, INA238_POWER, &regval);
+ if (err)
+ return err;
+
+ /* Fixed 1mA lsb, scaled by 1000000 to have result in uW */
+ power = div_u64(regval * 1000ULL * INA238_FIXED_SHUNT *
+ data->gain, 20 * data->rshunt);
+ /* Clamp value to maximum value of long */
+ *val = clamp_val(power, 0, LONG_MAX);
+ break;
+ case hwmon_power_max:
+ err = regmap_read(data->regmap, INA238_POWER_LIMIT, &regval);
+ if (err)
+ return err;
+
+ /*
+ * Truncated 24-bit compare register, lower 8-bits are
+ * truncated. Same conversion to/from uW as POWER register.
+ */
+ power = div_u64((regval << 8) * 1000ULL * INA238_FIXED_SHUNT *
+ data->gain, 20 * data->rshunt);
+ /* Clamp value to maximum value of long */
+ *val = clamp_val(power, 0, LONG_MAX);
+ break;
+ case hwmon_power_max_alarm:
+ err = regmap_read(data->regmap, INA238_DIAG_ALERT, &regval);
+ if (err)
+ return err;
+
+ *val = regval & INA238_DIAG_ALERT_POL ? 1 : 0;

*val = !!(regval & INA238_DIAG_ALERT_POL);

+ break;
+ default:
+ return -EOPNOTSUPP;
+ }
+
+ return 0;
+}
+
+static int ina238_write_power(struct device *dev, u32 attr, int channel,
+ long val)
+{
+ struct ina238_data *data = dev_get_drvdata(dev);
+ int regval;
+
+ if (channel != 0 || attr != hwmon_power_max)
+ return -EOPNOTSUPP;
+
+ /*
+ * Compared against the 24-bit power register, lower 8-bits are
+ * truncated. Same conversion to/from uW as POWER register.
+ */
+ regval = div_u64((u64)val * 20ULL * data->rshunt,
+ 1000ULL * INA238_FIXED_SHUNT * (u64)data->gain);

Same problem as above - negative values of val will have in unpredictable results.
The last typecat should be unnecessary.

+ regval = regval >> 8;
+ if (regval > U16_MAX || regval < 0)
+ return -EINVAL;

regval = clamp_val(...);

+
+ return regmap_write(data->regmap, INA238_POWER_LIMIT, regval);
+}
+
+static int ina238_read_temp(struct device *dev, u32 attr, int channel,
+ long *val)
+{
+ struct ina238_data *data = dev_get_drvdata(dev);
+ int regval;
+ int err;
+
+ if (channel != 0)
+ return -EOPNOTSUPP;
+
+ switch (attr) {
+ case hwmon_temp_input:
+ err = regmap_read(data->regmap, INA238_DIE_TEMP, &regval);
+ if (err)
+ return err;
+
+ /* Signed, bits 15-4 of register, result in mC */
+ *val = ((s16)regval >> 4) * INA238_DIE_TEMP_LSB;
+ break;
+ case hwmon_temp_max:
+ err = regmap_read(data->regmap, INA238_TEMP_LIMIT, &regval);
+ if (err)
+ return err;
+
+ /* Signed, bits 15-4 of register, result in mC */
+ *val = ((s16)regval >> 4) * INA238_DIE_TEMP_LSB;
+ break;
+ case hwmon_temp_max_alarm:
+ err = regmap_read(data->regmap, INA238_DIAG_ALERT, &regval);
+ if (err)
+ return err;
+
+ *val = regval & INA238_DIAG_ALERT_TMPOL ? 1 : 0;

*val = !!(regval & INA238_DIAG_ALERT_TMPOL);

+ break;
+ default:
+ return -EOPNOTSUPP;
+ }
+
+ return 0;
+}
+
+static int ina238_write_temp(struct device *dev, u32 attr, int channel,
+ long val)
+{
+ struct ina238_data *data = dev_get_drvdata(dev);
+ int regval;
+
+ if (channel != 0 || attr != hwmon_temp_max)
+ return -EOPNOTSUPP;
+
+ /* Signed, bits 15-4 of register */
+ regval = (div_s64(val, INA238_DIE_TEMP_LSB) << 4);
+ if (regval > S16_MAX || regval < S16_MIN)
+ return -EINVAL;

regval = clamp_val(regval, S16_MIN, S16_MAX) & 0xfff0;

+ regval = regval & 0xfff0;
+
+ return regmap_write(data->regmap, INA238_TEMP_LIMIT, regval);
+}
+
+static int ina238_read(struct device *dev, enum hwmon_sensor_types type,
+ u32 attr, int channel, long *val)
+{
+ switch (type) {
+ case hwmon_in:
+ return ina238_read_in(dev, attr, channel, val);
+ case hwmon_curr:
+ return ina238_read_current(dev, attr, channel, val);
+ case hwmon_power:
+ return ina238_read_power(dev, attr, channel, val);
+ case hwmon_temp:
+ return ina238_read_temp(dev, attr, channel, val);
+ default:
+ return -EOPNOTSUPP;
+ }
+ return 0;
+}
+
+static int ina238_write(struct device *dev, enum hwmon_sensor_types type,
+ u32 attr, int channel, long val)
+{
+ struct ina238_data *data = dev_get_drvdata(dev);
+ int err;
+
+ mutex_lock(&data->config_lock);
+
+ switch (type) {
+ case hwmon_in:
+ err = ina238_write_in(dev, attr, channel, val);
+ break;
+ case hwmon_power:
+ err = ina238_write_power(dev, attr, channel, val);
+ break;
+ case hwmon_temp:
+ err = ina238_write_temp(dev, attr, channel, val);
+ break;
+ default:
+ err = -EOPNOTSUPP;
+ break;
+ }
+
+ mutex_unlock(&data->config_lock);
+ return err;
+}
+
+static umode_t ina238_is_visible(const void *drvdata,
+ enum hwmon_sensor_types type,
+ u32 attr, int channel)
+{
+ switch (type) {
+ case hwmon_in:
+ if (channel != 0 && channel != 1)
+ return 0;

FWIW, channel checks are not really needed.

+
+ switch (attr) {
+ case hwmon_in_input:
+ case hwmon_in_max_alarm:
+ case hwmon_in_min_alarm:
+ return 0444;
+ case hwmon_in_max:
+ case hwmon_in_min:
+ return 0644;
+ default:
+ return 0;
+ }
+ case hwmon_curr:
+ if (channel != 0)
+ return 0;
+
+ switch (attr) {
+ case hwmon_curr_input:
+ return 0444;
+ default:
+ return 0;
+ }
+ case hwmon_power:
+ if (channel != 0)
+ return 0;
+
+ switch (attr) {
+ case hwmon_power_input:
+ case hwmon_power_max_alarm:
+ return 0444;
+ case hwmon_power_max:
+ return 0644;
+ default:
+ return 0;
+ }
+ case hwmon_temp:
+ if (channel != 0)
+ return 0;
+
+ switch (attr) {
+ case hwmon_temp_input:
+ case hwmon_temp_max_alarm:
+ return 0444;
+ case hwmon_temp_max:
+ return 0644;
+ default:
+ return 0;
+ }
+ default:
+ return 0;
+ }
+}
+
+#define INA238_HWMON_IN_CONFIG (HWMON_I_INPUT | \
+ HWMON_I_MAX | HWMON_I_MAX_ALARM | \
+ HWMON_I_MIN | HWMON_I_MIN_ALARM)
+
+static const struct hwmon_channel_info *ina238_info[] = {
+ HWMON_CHANNEL_INFO(in,
+ /* 0: shunt voltage */
+ INA238_HWMON_IN_CONFIG,
+ /* 1: bus voltage */
+ INA238_HWMON_IN_CONFIG),
+ HWMON_CHANNEL_INFO(curr,
+ /* 0: current through shunt */
+ HWMON_C_INPUT),
+ HWMON_CHANNEL_INFO(power,
+ /* 0: power */
+ HWMON_P_INPUT | HWMON_P_MAX | HWMON_P_MAX_ALARM),
+ HWMON_CHANNEL_INFO(temp,
+ /* 0: die temperature */
+ HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_MAX_ALARM),
+ NULL
+};
+
+static const struct hwmon_ops ina238_hwmon_ops = {
+ .is_visible = ina238_is_visible,
+ .read = ina238_read,
+ .write = ina238_write,
+};
+
+static const struct hwmon_chip_info ina238_chip_info = {
+ .ops = &ina238_hwmon_ops,
+ .info = ina238_info,
+};
+
+static int ina238_probe(struct i2c_client *client)
+{
+ struct ina2xx_platform_data *pdata = dev_get_platdata(&client->dev);
+ struct device *dev = &client->dev;
+ struct device *hwmon_dev;
+ struct ina238_data *data;
+ int config;
+ int ret;
+
+ data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ data->client = client;
+ /* set the device type */

Pointless comment. I don't even understand what it is supposed to mean.

+ mutex_init(&data->config_lock);
+
+ data->regmap = devm_regmap_init_i2c(client, &ina238_regmap_config);
+ if (IS_ERR(data->regmap)) {
+ dev_err(dev, "failed to allocate register map\n");
+ return PTR_ERR(data->regmap);
+ }
+
+ /* load shunt value */
+ data->rshunt = INA238_RSHUNT_DEFAULT;
+ if (device_property_read_u32(dev, "shunt-resistor", &data->rshunt) < 0 &&
+ pdata)

Drop the continuation line. Lines longer than 80 columns are fine when
improving readability, and that is definitely the case here.

+ data->rshunt = pdata->shunt_uohms;
+ if (data->rshunt == 0) {
+ dev_err(dev, "invalid shunt resister value %u\n", data->rshunt);
+ return -EINVAL;
+ }
+
+ /* load shunt gain value */
+ if (device_property_read_u32(dev, "ti,shunt-gain", &data->gain) < 0)
+ data->gain = 4; /* Default of ADCRANGE = 0 */
+ if (data->gain != 1 && data->gain != 4) {
+ dev_err(dev, "invalid shunt gain value %u\n", data->gain);
+ return -EINVAL;
+ }

I think ti,shunt-gain needs a better explanation in the .yaml file, for
people writing devicetree files to understand how the gain value converts
to a register value.

+
+ /* Setup CONFIG register */
+ config = INA238_CONFIG_DEFAULT;
+ if (data->gain == 1)
+ config |= INA238_CONFIG_ADCRANGE; /* ADCRANGE = 1 is /1 */
+ ret = regmap_write(data->regmap, INA238_CONFIG, config);
+ if (ret < 0) {
+ dev_err(dev, "error configuring the device: %d\n", ret);
+ return -ENODEV;
+ }
+
+ /* Setup ADC_CONFIG register */
+ ret = regmap_write(data->regmap, INA238_ADC_CONFIG,
+ INA238_ADC_CONFIG_DEFAULT);
+ if (ret < 0) {
+ dev_err(dev, "error configuring the device: %d\n", ret);
+ return -ENODEV;
+ }
+
+ /* Setup SHUNT_CALIBRATION register with fixed value */
+ ret = regmap_write(data->regmap, INA238_SHUNT_CALIBRATION,
+ INA238_CALIBRATION_VALUE);
+ if (ret < 0) {
+ dev_err(dev, "error configuring the device: %d\n", ret);
+ return -ENODEV;
+ }
+
+ /* Setup alert/alarm configuration */
+ ret = regmap_write(data->regmap, INA238_DIAG_ALERT,
+ INA238_DIAG_ALERT_DEFAULT);
+ if (ret < 0) {
+ dev_err(dev, "error configuring the device: %d\n", ret);
+ return -ENODEV;
+ }
+
+ hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, data,
+ &ina238_chip_info,
+ NULL);
+ if (IS_ERR(hwmon_dev))
+ return PTR_ERR(hwmon_dev);
+
+ dev_info(dev, "power monitor %s (Rshunt = %u uOhm, gain = %u)\n",
+ client->name, data->rshunt, data->gain);
+
+ return 0;
+}
+
+static const struct i2c_device_id ina238_id[] = {
+ { "ina238", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, ina238_id);
+
+static const struct of_device_id __maybe_unused ina238_of_match[] = {
+ { .compatible = "ti,ina238" },
+ { },
+};
+MODULE_DEVICE_TABLE(of, ina238_of_match);
+
+static struct i2c_driver ina238_driver = {
+ .class = I2C_CLASS_HWMON,
+ .driver = {
+ .name = "ina238",
+ .of_match_table = of_match_ptr(ina238_of_match),
+ },
+ .probe_new = ina238_probe,
+ .id_table = ina238_id,
+};
+
+module_i2c_driver(ina238_driver);
+
+MODULE_AUTHOR("Nathan Rossi <nathan.rossi@xxxxxxxx>");
+MODULE_DESCRIPTION("ina238 driver");
+MODULE_LICENSE("GPL");
---
2.33.0