567 lines
14 KiB
C
567 lines
14 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* iio/adc/max9611.c
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*
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* Maxim max9611/max9612 high side current sense amplifier with
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* 12-bit ADC interface.
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*
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* Copyright (C) 2017 Jacopo Mondi
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*/
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/*
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* This driver supports input common-mode voltage, current-sense
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* amplifier with programmable gains and die temperature reading from
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* Maxim max9611/max9612.
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*
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* Op-amp, analog comparator, and watchdog functionalities are not
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* supported by this driver.
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*/
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#include <linux/delay.h>
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#include <linux/i2c.h>
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#include <linux/iio/iio.h>
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#include <linux/iio/sysfs.h>
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#include <linux/module.h>
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#include <linux/mod_devicetable.h>
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#include <linux/property.h>
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#define DRIVER_NAME "max9611"
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/* max9611 register addresses */
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#define MAX9611_REG_CSA_DATA 0x00
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#define MAX9611_REG_RS_DATA 0x02
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#define MAX9611_REG_TEMP_DATA 0x08
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#define MAX9611_REG_CTRL1 0x0a
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#define MAX9611_REG_CTRL2 0x0b
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/* max9611 REG1 mux configuration options */
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#define MAX9611_MUX_MASK GENMASK(3, 0)
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#define MAX9611_MUX_SENSE_1x 0x00
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#define MAX9611_MUX_SENSE_4x 0x01
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#define MAX9611_MUX_SENSE_8x 0x02
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#define MAX9611_INPUT_VOLT 0x03
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#define MAX9611_MUX_TEMP 0x06
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/* max9611 voltage (both csa and input) helper macros */
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#define MAX9611_VOLTAGE_SHIFT 0x04
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#define MAX9611_VOLTAGE_RAW(_r) ((_r) >> MAX9611_VOLTAGE_SHIFT)
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/*
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* max9611 current sense amplifier voltage output:
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* LSB and offset values depends on selected gain (1x, 4x, 8x)
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*
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* GAIN LSB (nV) OFFSET (LSB steps)
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* 1x 107500 1
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* 4x 26880 1
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* 8x 13440 3
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*
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* The complete formula to calculate current sense voltage is:
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* (((adc_read >> 4) - offset) / ((1 / LSB) * 10^-3)
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*/
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#define MAX9611_CSA_1X_LSB_nV 107500
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#define MAX9611_CSA_4X_LSB_nV 26880
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#define MAX9611_CSA_8X_LSB_nV 13440
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#define MAX9611_CSA_1X_OFFS_RAW 1
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#define MAX9611_CSA_4X_OFFS_RAW 1
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#define MAX9611_CSA_8X_OFFS_RAW 3
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/*
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* max9611 common input mode (CIM): LSB is 14mV, with 14mV offset at 25 C
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*
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* The complete formula to calculate input common voltage is:
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* (((adc_read >> 4) * 1000) - offset) / (1 / 14 * 1000)
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*/
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#define MAX9611_CIM_LSB_mV 14
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#define MAX9611_CIM_OFFSET_RAW 1
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/*
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* max9611 temperature reading: LSB is 480 milli degrees Celsius
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*
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* The complete formula to calculate temperature is:
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* ((adc_read >> 7) * 1000) / (1 / 480 * 1000)
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*/
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#define MAX9611_TEMP_MAX_POS 0x7f80
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#define MAX9611_TEMP_MAX_NEG 0xff80
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#define MAX9611_TEMP_MIN_NEG 0xd980
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#define MAX9611_TEMP_MASK GENMASK(15, 7)
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#define MAX9611_TEMP_SHIFT 0x07
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#define MAX9611_TEMP_RAW(_r) ((_r) >> MAX9611_TEMP_SHIFT)
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#define MAX9611_TEMP_SCALE_NUM 1000000
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#define MAX9611_TEMP_SCALE_DIV 2083
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/*
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* Conversion time is 2 ms (typically) at Ta=25 degreeC
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* No maximum value is known, so play it safe.
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*/
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#define MAX9611_CONV_TIME_US_RANGE 3000, 3300
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struct max9611_dev {
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struct device *dev;
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struct i2c_client *i2c_client;
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struct mutex lock;
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unsigned int shunt_resistor_uohm;
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};
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enum max9611_conf_ids {
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CONF_SENSE_1x,
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CONF_SENSE_4x,
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CONF_SENSE_8x,
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CONF_IN_VOLT,
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CONF_TEMP,
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};
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/*
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* max9611_mux_conf - associate ADC mux configuration with register address
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* where data shall be read from
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*/
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static const unsigned int max9611_mux_conf[][2] = {
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[CONF_SENSE_1x] = { MAX9611_MUX_SENSE_1x, MAX9611_REG_CSA_DATA },
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[CONF_SENSE_4x] = { MAX9611_MUX_SENSE_4x, MAX9611_REG_CSA_DATA },
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[CONF_SENSE_8x] = { MAX9611_MUX_SENSE_8x, MAX9611_REG_CSA_DATA },
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[CONF_IN_VOLT] = { MAX9611_INPUT_VOLT, MAX9611_REG_RS_DATA },
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[CONF_TEMP] = { MAX9611_MUX_TEMP, MAX9611_REG_TEMP_DATA },
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};
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enum max9611_csa_gain {
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CSA_GAIN_1x = CONF_SENSE_1x,
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CSA_GAIN_4x = CONF_SENSE_4x,
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CSA_GAIN_8x = CONF_SENSE_8x,
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};
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enum max9611_csa_gain_params {
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CSA_GAIN_LSB_nV,
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CSA_GAIN_OFFS_RAW,
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};
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/*
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* max9611_csa_gain_conf - associate gain multiplier with LSB and
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* offset values.
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*
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* Group together parameters associated with configurable gain
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* on current sense amplifier path to ADC interface.
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* Current sense read routine adjusts gain until it gets a meaningful
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* value; use this structure to retrieve the correct LSB and offset values.
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*/
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static const unsigned int max9611_gain_conf[][2] = {
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[CSA_GAIN_1x] = { MAX9611_CSA_1X_LSB_nV, MAX9611_CSA_1X_OFFS_RAW, },
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[CSA_GAIN_4x] = { MAX9611_CSA_4X_LSB_nV, MAX9611_CSA_4X_OFFS_RAW, },
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[CSA_GAIN_8x] = { MAX9611_CSA_8X_LSB_nV, MAX9611_CSA_8X_OFFS_RAW, },
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};
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enum max9611_chan_addrs {
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MAX9611_CHAN_VOLTAGE_INPUT,
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MAX9611_CHAN_VOLTAGE_SENSE,
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MAX9611_CHAN_TEMPERATURE,
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MAX9611_CHAN_CURRENT_LOAD,
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MAX9611_CHAN_POWER_LOAD,
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};
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static const struct iio_chan_spec max9611_channels[] = {
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{
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.type = IIO_TEMP,
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.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
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BIT(IIO_CHAN_INFO_SCALE),
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.address = MAX9611_CHAN_TEMPERATURE,
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},
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{
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.type = IIO_VOLTAGE,
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.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
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.address = MAX9611_CHAN_VOLTAGE_SENSE,
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.indexed = 1,
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.channel = 0,
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},
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{
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.type = IIO_VOLTAGE,
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.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
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BIT(IIO_CHAN_INFO_SCALE) |
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BIT(IIO_CHAN_INFO_OFFSET),
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.address = MAX9611_CHAN_VOLTAGE_INPUT,
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.indexed = 1,
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.channel = 1,
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},
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{
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.type = IIO_CURRENT,
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.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
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.address = MAX9611_CHAN_CURRENT_LOAD,
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},
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{
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.type = IIO_POWER,
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.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
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.address = MAX9611_CHAN_POWER_LOAD
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},
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};
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/**
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* max9611_read_single() - read a single value from ADC interface
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*
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* Data registers are 16 bit long, spread between two 8 bit registers
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* with consecutive addresses.
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* Configure ADC mux first, then read register at address "reg_addr".
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* The smbus_read_word routine asks for 16 bits and the ADC is kind enough
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* to return values from "reg_addr" and "reg_addr + 1" consecutively.
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* Data are transmitted with big-endian ordering: MSB arrives first.
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*
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* @max9611: max9611 device
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* @selector: index for mux and register configuration
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* @raw_val: the value returned from ADC
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*/
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static int max9611_read_single(struct max9611_dev *max9611,
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enum max9611_conf_ids selector,
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u16 *raw_val)
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{
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int ret;
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u8 mux_conf = max9611_mux_conf[selector][0] & MAX9611_MUX_MASK;
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u8 reg_addr = max9611_mux_conf[selector][1];
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/*
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* Keep mutex lock held during read-write to avoid mux register
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* (CTRL1) re-configuration.
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*/
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mutex_lock(&max9611->lock);
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ret = i2c_smbus_write_byte_data(max9611->i2c_client,
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MAX9611_REG_CTRL1, mux_conf);
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if (ret) {
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dev_err(max9611->dev, "i2c write byte failed: 0x%2x - 0x%2x\n",
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MAX9611_REG_CTRL1, mux_conf);
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mutex_unlock(&max9611->lock);
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return ret;
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}
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/* need a delay here to make register configuration stabilize. */
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usleep_range(MAX9611_CONV_TIME_US_RANGE);
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ret = i2c_smbus_read_word_swapped(max9611->i2c_client, reg_addr);
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if (ret < 0) {
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dev_err(max9611->dev, "i2c read word from 0x%2x failed\n",
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reg_addr);
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mutex_unlock(&max9611->lock);
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return ret;
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}
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*raw_val = ret;
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mutex_unlock(&max9611->lock);
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return 0;
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}
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/**
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* max9611_read_csa_voltage() - read current sense amplifier output voltage
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*
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* Current sense amplifier output voltage is read through a configurable
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* 1x, 4x or 8x gain.
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* Start with plain 1x gain, and adjust gain control properly until a
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* meaningful value is read from ADC output.
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*
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* @max9611: max9611 device
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* @adc_raw: raw value read from ADC output
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* @csa_gain: gain configuration option selector
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*/
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static int max9611_read_csa_voltage(struct max9611_dev *max9611,
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u16 *adc_raw,
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enum max9611_csa_gain *csa_gain)
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{
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enum max9611_conf_ids gain_selectors[] = {
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CONF_SENSE_1x,
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CONF_SENSE_4x,
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CONF_SENSE_8x
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};
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unsigned int i;
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int ret;
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for (i = 0; i < ARRAY_SIZE(gain_selectors); ++i) {
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ret = max9611_read_single(max9611, gain_selectors[i], adc_raw);
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if (ret)
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return ret;
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if (*adc_raw > 0) {
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*csa_gain = (enum max9611_csa_gain)gain_selectors[i];
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return 0;
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}
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}
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return -EIO;
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}
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static int max9611_read_raw(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan,
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int *val, int *val2, long mask)
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{
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struct max9611_dev *dev = iio_priv(indio_dev);
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enum max9611_csa_gain gain_selector;
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const unsigned int *csa_gain;
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u16 adc_data;
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int ret;
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switch (mask) {
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case IIO_CHAN_INFO_RAW:
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switch (chan->address) {
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case MAX9611_CHAN_TEMPERATURE:
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ret = max9611_read_single(dev, CONF_TEMP,
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&adc_data);
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if (ret)
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return -EINVAL;
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*val = MAX9611_TEMP_RAW(adc_data);
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return IIO_VAL_INT;
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case MAX9611_CHAN_VOLTAGE_INPUT:
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ret = max9611_read_single(dev, CONF_IN_VOLT,
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&adc_data);
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if (ret)
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return -EINVAL;
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*val = MAX9611_VOLTAGE_RAW(adc_data);
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return IIO_VAL_INT;
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}
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break;
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case IIO_CHAN_INFO_OFFSET:
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/* MAX9611_CHAN_VOLTAGE_INPUT */
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*val = MAX9611_CIM_OFFSET_RAW;
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return IIO_VAL_INT;
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case IIO_CHAN_INFO_SCALE:
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switch (chan->address) {
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case MAX9611_CHAN_TEMPERATURE:
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*val = MAX9611_TEMP_SCALE_NUM;
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*val2 = MAX9611_TEMP_SCALE_DIV;
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return IIO_VAL_FRACTIONAL;
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case MAX9611_CHAN_VOLTAGE_INPUT:
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*val = MAX9611_CIM_LSB_mV;
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return IIO_VAL_INT;
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}
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break;
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case IIO_CHAN_INFO_PROCESSED:
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switch (chan->address) {
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case MAX9611_CHAN_VOLTAGE_SENSE:
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/*
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* processed (mV): (raw - offset) * LSB (nV) / 10^6
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*
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* Even if max9611 can output raw csa voltage readings,
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* use a produced value as scale depends on gain.
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*/
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ret = max9611_read_csa_voltage(dev, &adc_data,
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&gain_selector);
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if (ret)
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return -EINVAL;
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csa_gain = max9611_gain_conf[gain_selector];
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adc_data -= csa_gain[CSA_GAIN_OFFS_RAW];
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*val = MAX9611_VOLTAGE_RAW(adc_data) *
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csa_gain[CSA_GAIN_LSB_nV];
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*val2 = 1000000;
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return IIO_VAL_FRACTIONAL;
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case MAX9611_CHAN_CURRENT_LOAD:
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/* processed (mA): Vcsa (nV) / Rshunt (uOhm) */
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ret = max9611_read_csa_voltage(dev, &adc_data,
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&gain_selector);
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if (ret)
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return -EINVAL;
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csa_gain = max9611_gain_conf[gain_selector];
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adc_data -= csa_gain[CSA_GAIN_OFFS_RAW];
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*val = MAX9611_VOLTAGE_RAW(adc_data) *
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csa_gain[CSA_GAIN_LSB_nV];
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*val2 = dev->shunt_resistor_uohm;
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return IIO_VAL_FRACTIONAL;
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case MAX9611_CHAN_POWER_LOAD:
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/*
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* processed (mW): Vin (mV) * Vcsa (uV) /
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* Rshunt (uOhm)
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*/
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ret = max9611_read_single(dev, CONF_IN_VOLT,
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&adc_data);
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if (ret)
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return -EINVAL;
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adc_data -= MAX9611_CIM_OFFSET_RAW;
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*val = MAX9611_VOLTAGE_RAW(adc_data) *
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MAX9611_CIM_LSB_mV;
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ret = max9611_read_csa_voltage(dev, &adc_data,
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&gain_selector);
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if (ret)
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return -EINVAL;
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csa_gain = max9611_gain_conf[gain_selector];
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/* divide by 10^3 here to avoid 32bit overflow */
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adc_data -= csa_gain[CSA_GAIN_OFFS_RAW];
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*val *= MAX9611_VOLTAGE_RAW(adc_data) *
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csa_gain[CSA_GAIN_LSB_nV] / 1000;
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*val2 = dev->shunt_resistor_uohm;
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return IIO_VAL_FRACTIONAL;
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}
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break;
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}
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return -EINVAL;
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}
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static ssize_t max9611_shunt_resistor_show(struct device *dev,
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struct device_attribute *attr,
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char *buf)
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{
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struct max9611_dev *max9611 = iio_priv(dev_to_iio_dev(dev));
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unsigned int i, r;
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i = max9611->shunt_resistor_uohm / 1000000;
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r = max9611->shunt_resistor_uohm % 1000000;
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return sysfs_emit(buf, "%u.%06u\n", i, r);
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}
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static IIO_DEVICE_ATTR(in_power_shunt_resistor, 0444,
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max9611_shunt_resistor_show, NULL, 0);
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static IIO_DEVICE_ATTR(in_current_shunt_resistor, 0444,
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max9611_shunt_resistor_show, NULL, 0);
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static struct attribute *max9611_attributes[] = {
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&iio_dev_attr_in_power_shunt_resistor.dev_attr.attr,
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&iio_dev_attr_in_current_shunt_resistor.dev_attr.attr,
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NULL,
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};
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static const struct attribute_group max9611_attribute_group = {
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.attrs = max9611_attributes,
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};
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static const struct iio_info indio_info = {
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.read_raw = max9611_read_raw,
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.attrs = &max9611_attribute_group,
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};
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static int max9611_init(struct max9611_dev *max9611)
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{
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struct i2c_client *client = max9611->i2c_client;
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u16 regval;
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int ret;
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if (!i2c_check_functionality(client->adapter,
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I2C_FUNC_SMBUS_WRITE_BYTE |
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I2C_FUNC_SMBUS_READ_WORD_DATA)) {
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dev_err(max9611->dev,
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"I2c adapter does not support smbus write_byte or read_word functionalities: aborting probe.\n");
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return -EINVAL;
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}
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/* Make sure die temperature is in range to test communications. */
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ret = max9611_read_single(max9611, CONF_TEMP, ®val);
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if (ret)
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return ret;
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regval &= MAX9611_TEMP_MASK;
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if ((regval > MAX9611_TEMP_MAX_POS &&
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regval < MAX9611_TEMP_MIN_NEG) ||
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regval > MAX9611_TEMP_MAX_NEG) {
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dev_err(max9611->dev,
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"Invalid value received from ADC 0x%4x: aborting\n",
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|
regval);
|
|
return -EIO;
|
|
}
|
|
|
|
/* Mux shall be zeroed back before applying other configurations */
|
|
ret = i2c_smbus_write_byte_data(max9611->i2c_client,
|
|
MAX9611_REG_CTRL1, 0);
|
|
if (ret) {
|
|
dev_err(max9611->dev, "i2c write byte failed: 0x%2x - 0x%2x\n",
|
|
MAX9611_REG_CTRL1, 0);
|
|
return ret;
|
|
}
|
|
|
|
ret = i2c_smbus_write_byte_data(max9611->i2c_client,
|
|
MAX9611_REG_CTRL2, 0);
|
|
if (ret) {
|
|
dev_err(max9611->dev, "i2c write byte failed: 0x%2x - 0x%2x\n",
|
|
MAX9611_REG_CTRL2, 0);
|
|
return ret;
|
|
}
|
|
usleep_range(MAX9611_CONV_TIME_US_RANGE);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const struct of_device_id max9611_of_table[] = {
|
|
{.compatible = "maxim,max9611", .data = "max9611"},
|
|
{.compatible = "maxim,max9612", .data = "max9612"},
|
|
{ },
|
|
};
|
|
|
|
MODULE_DEVICE_TABLE(of, max9611_of_table);
|
|
static int max9611_probe(struct i2c_client *client,
|
|
const struct i2c_device_id *id)
|
|
{
|
|
const char * const shunt_res_prop = "shunt-resistor-micro-ohms";
|
|
struct max9611_dev *max9611;
|
|
struct iio_dev *indio_dev;
|
|
struct device *dev = &client->dev;
|
|
unsigned int of_shunt;
|
|
int ret;
|
|
|
|
indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*max9611));
|
|
if (!indio_dev)
|
|
return -ENOMEM;
|
|
|
|
i2c_set_clientdata(client, indio_dev);
|
|
|
|
max9611 = iio_priv(indio_dev);
|
|
max9611->dev = dev;
|
|
max9611->i2c_client = client;
|
|
mutex_init(&max9611->lock);
|
|
|
|
ret = device_property_read_u32(dev, shunt_res_prop, &of_shunt);
|
|
if (ret) {
|
|
dev_err(dev, "Missing %s property for %pfw node\n",
|
|
shunt_res_prop, dev_fwnode(dev));
|
|
return ret;
|
|
}
|
|
max9611->shunt_resistor_uohm = of_shunt;
|
|
|
|
ret = max9611_init(max9611);
|
|
if (ret)
|
|
return ret;
|
|
|
|
indio_dev->name = device_get_match_data(dev);
|
|
indio_dev->modes = INDIO_DIRECT_MODE;
|
|
indio_dev->info = &indio_info;
|
|
indio_dev->channels = max9611_channels;
|
|
indio_dev->num_channels = ARRAY_SIZE(max9611_channels);
|
|
|
|
return devm_iio_device_register(dev, indio_dev);
|
|
}
|
|
|
|
static struct i2c_driver max9611_driver = {
|
|
.driver = {
|
|
.name = DRIVER_NAME,
|
|
.of_match_table = max9611_of_table,
|
|
},
|
|
.probe = max9611_probe,
|
|
};
|
|
module_i2c_driver(max9611_driver);
|
|
|
|
MODULE_AUTHOR("Jacopo Mondi <jacopo+renesas@jmondi.org>");
|
|
MODULE_DESCRIPTION("Maxim max9611/12 current sense amplifier with 12bit ADC");
|
|
MODULE_LICENSE("GPL v2");
|