// 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 <[email protected]> */ #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 … #define INA238_ADC_CONFIG … #define INA238_SHUNT_CALIBRATION … #define INA238_SHUNT_VOLTAGE … #define INA238_BUS_VOLTAGE … #define INA238_DIE_TEMP … #define INA238_CURRENT … #define INA238_POWER … #define INA238_DIAG_ALERT … #define INA238_SHUNT_OVER_VOLTAGE … #define INA238_SHUNT_UNDER_VOLTAGE … #define INA238_BUS_OVER_VOLTAGE … #define INA238_BUS_UNDER_VOLTAGE … #define INA238_TEMP_LIMIT … #define INA238_POWER_LIMIT … #define INA238_DEVICE_ID … #define INA238_CONFIG_ADCRANGE … #define INA238_DIAG_ALERT_TMPOL … #define INA238_DIAG_ALERT_SHNTOL … #define INA238_DIAG_ALERT_SHNTUL … #define INA238_DIAG_ALERT_BUSOL … #define INA238_DIAG_ALERT_BUSUL … #define INA238_DIAG_ALERT_POL … #define INA238_REGISTERS … #define INA238_RSHUNT_DEFAULT … /* Default configuration of device on reset. */ #define INA238_CONFIG_DEFAULT … /* 16 sample averaging, 1052us conversion time, continuous mode */ #define INA238_ADC_CONFIG_DEFAULT … /* Configure alerts to be based on averaged value (SLOWALERT) */ #define INA238_DIAG_ALERT_DEFAULT … /* * 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 … #define INA238_FIXED_SHUNT … #define INA238_SHUNT_VOLTAGE_LSB … #define INA238_BUS_VOLTAGE_LSB … #define INA238_DIE_TEMP_LSB … static const struct regmap_config ina238_regmap_config = …; struct ina238_data { … }; static int ina238_read_reg24(const struct i2c_client *client, u8 reg, u32 *val) { … } static int ina238_read_in(struct device *dev, u32 attr, int channel, long *val) { … } static int ina238_write_in(struct device *dev, u32 attr, int channel, long val) { … } static int ina238_read_current(struct device *dev, u32 attr, long *val) { … } static int ina238_read_power(struct device *dev, u32 attr, long *val) { … } static int ina238_write_power(struct device *dev, u32 attr, long val) { … } static int ina238_read_temp(struct device *dev, u32 attr, long *val) { … } static int ina238_write_temp(struct device *dev, u32 attr, long val) { … } static int ina238_read(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel, long *val) { … } static int ina238_write(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel, long val) { … } static umode_t ina238_is_visible(const void *drvdata, enum hwmon_sensor_types type, u32 attr, int channel) { … } #define INA238_HWMON_IN_CONFIG … static const struct hwmon_channel_info * const ina238_info[] = …; static const struct hwmon_ops ina238_hwmon_ops = …; static const struct hwmon_chip_info ina238_chip_info = …; static int ina238_probe(struct i2c_client *client) { … } static const struct i2c_device_id ina238_id[] = …; MODULE_DEVICE_TABLE(i2c, ina238_id); static const struct of_device_id __maybe_unused ina238_of_match[] = …; MODULE_DEVICE_TABLE(of, ina238_of_match); static struct i2c_driver ina238_driver = …; module_i2c_driver(…) …; MODULE_AUTHOR(…) …; MODULE_DESCRIPTION(…) …; MODULE_LICENSE(…) …;
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