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From:   Nathan Rossi <nathan@nathanrossi.com>
Date:   Mon, 1 Nov 2021 12:20:36 +1000
Message-ID: <CA+aJhH1aGJXwYSCU8RC275G5=qGLyZRK94g9ic24wxKuRGCwEA@mail.gmail.com>
Subject: Re: [PATCH v3 3/3] hwmon: Driver for Texas Instruments INA238
To:     Guenter Roeck <linux@roeck-us.net>
Cc:     linux-hwmon@vger.kernel.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, Nathan Rossi <nathan.rossi@digi.com>,
        Jean Delvare <jdelvare@suse.com>,
        Jonathan Corbet <corbet@lwn.net>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Fri, 29 Oct 2021 at 20:11, Guenter Roeck <linux@roeck-us.net> wrote:
>
> On 10/28/21 1:10 AM, Nathan Rossi wrote:
> > From: Nathan Rossi <nathan.rossi@digi.com>
> >
> > 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@digi.com>
> > ---
> > 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
> >
> > Changes in v3:
> > - Remove unnecessary header include
> > - Change ina238_read_reg24 to return EIO when invalid byte count is read
> >    from device
> > - Replace '? 1 : 0' with '!!'
> > - Clamp the input value of attributes before calculating the associated
> >    register value, this avoids issues with negative values and avoids
> >    some of the need to perform 64-bit calculations
> > - Check the use of 64-bit divides and replace where possible
> >    - The current and power calculations still use 64-bit calculations due
> >      to maintaining precision while correcting for difference between
> >      calibrated and actual shunt values (micro ohm value multiplication
> >      causes overflow of long)
> > - Remove channel index checks and passing channel value to read/write
> >    functions
> > ---
> >   Documentation/hwmon/ina238.rst |  56 ++++
> >   Documentation/hwmon/index.rst  |   1 +
> >   drivers/hwmon/Kconfig          |  12 +
> >   drivers/hwmon/Makefile         |   1 +
> >   drivers/hwmon/ina238.c         | 644 +++++++++++++++++++++++++++++++++++++++++
> >   5 files changed, 714 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@digi.com>
> > +
> > +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..fd830e2582
> > --- /dev/null
> > +++ b/drivers/hwmon/ina238.c
> > @@ -0,0 +1,644 @@
> > +// 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@digi.com>
> > + */
> > +
> > +#include <linux/err.h>
> > +#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 < 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 */
> > +             regval = (s16)regval;
> > +             if (channel == 0)
> > +                     /* gain of 1 -> LSB / 4 */
> > +                     *val = (regval * INA238_SHUNT_VOLTAGE_LSB) /
> > +                            (1000 * (4 - (int)data->gain + 1));
> > +             else
> > +                     *val = (regval * INA238_BUS_VOLTAGE_LSB) / 1000;
>
> Those calculations make me wonder: Are you sure you want to use divide operations
> instead of DIV_ROUND_CLOSEST() ? That applies to all divide operations.

I avoided DIV_ROUND_CLOSEST to avoid conditions where the _input
attributes would read values above the set alarm thresholds when they
are not actually above the thresholds (which could lead to confusion).

>
> > +             break;
> > +     case hwmon_in_max_alarm:
> > +     case hwmon_in_min_alarm:
> > +             *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);
> > +     long regval;
>
> nit: int should be sufficient here.
>
> > +
> > +     if (attr != hwmon_in_max && attr != hwmon_in_min)
> > +             return -EOPNOTSUPP;
> > +
> > +     /* convert decimal to register value */
> > +     switch (channel) {
> > +     case 0:
> > +             /* signed value, clamp to max range +/-163 mV */
> > +             regval = clamp_val(val, -163, 163);
> > +             regval = (regval * 1000L * (4 - (int)data->gain + 1)) /
>
> nit: The typecast "(int)" is not needed here.

Due to the unsigned type of gain, it causes promotion of regval (and
the rest of the numerator) to unsigned long which causes issues with
negative numbers on the divide. It makes more sense for gain to be an
int to begin with, I will change it to int to avoid the need for type
casting.

Regards,
Nathan

>
> > +                      INA238_SHUNT_VOLTAGE_LSB;
> > +             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:
> > +             /* signed value, positive values only. Clamp to max 102.396 V */
> > +             regval = clamp_val(val, 0, 102396);
> > +             regval = (regval * 1000) / INA238_BUS_VOLTAGE_LSB;
> > +             regval = clamp_val(regval, 0, S16_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, long *val)
> > +{
> > +     struct ina238_data *data = dev_get_drvdata(dev);
> > +     int regval;
> > +     int err;
> > +
> > +     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, long *val)
> > +{
> > +     struct ina238_data *data = dev_get_drvdata(dev);
> > +     long long power;
> > +     int regval;
> > +     int err;
> > +
> > +     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);
> > +             break;
> > +     default:
> > +             return -EOPNOTSUPP;
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> > +static int ina238_write_power(struct device *dev, u32 attr, long val)
> > +{
> > +     struct ina238_data *data = dev_get_drvdata(dev);
> > +     long regval;
> > +
> > +     if (attr != hwmon_power_max)
> > +             return -EOPNOTSUPP;
> > +
> > +     /*
> > +      * Unsigned postive values. Compared against the 24-bit power register,
> > +      * lower 8-bits are truncated. Same conversion to/from uW as POWER
> > +      * register.
> > +      */
> > +     regval = clamp_val(val, 0, LONG_MAX);
> > +     regval = div_u64(val * 20ULL * data->rshunt,
> > +                      1000ULL * INA238_FIXED_SHUNT * data->gain);
> > +     regval = clamp_val(regval >> 8, 0, U16_MAX);
> > +
> > +     return regmap_write(data->regmap, INA238_POWER_LIMIT, regval);
> > +}
> > +
> > +static int ina238_read_temp(struct device *dev, u32 attr, long *val)
> > +{
> > +     struct ina238_data *data = dev_get_drvdata(dev);
> > +     int regval;
> > +     int err;
> > +
> > +     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);
> > +             break;
> > +     default:
> > +             return -EOPNOTSUPP;
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> > +static int ina238_write_temp(struct device *dev, u32 attr, long val)
> > +{
> > +     struct ina238_data *data = dev_get_drvdata(dev);
> > +     int regval;
> > +
> > +     if (attr != hwmon_temp_max)
> > +             return -EOPNOTSUPP;
> > +
> > +     /* Signed, bits 15-4 of register */
> > +     regval = (val / INA238_DIE_TEMP_LSB) << 4;
> > +     regval = clamp_val(regval, S16_MIN, S16_MAX) & 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, val);
> > +     case hwmon_power:
> > +             return ina238_read_power(dev, attr, val);
> > +     case hwmon_temp:
> > +             return ina238_read_temp(dev, attr, 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, val);
> > +             break;
> > +     case hwmon_temp:
> > +             err = ina238_write_temp(dev, attr, 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:
> > +             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:
> > +             switch (attr) {
> > +             case hwmon_curr_input:
> > +                     return 0444;
> > +             default:
> > +                     return 0;
> > +             }
> > +     case hwmon_power:
> > +             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:
> > +             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;
> > +     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)
> > +             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;
> > +     }
> > +
> > +     /* 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@digi.com>");
> > +MODULE_DESCRIPTION("ina238 driver");
> > +MODULE_LICENSE("GPL");
> > ---
> > 2.33.0
> >
>