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linux/drivers/iio/adc/max9611.c
Jonathan Cameron a8375d704d iio:adc:max9611: Drop explicit setting of the i2c module owner. 
This has been handled by the i2c core for some time.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
2017-09-03 18:10:25 +01:00

584 lines
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/*
* iio/adc/max9611.c
*
* Maxim max9611/max9612 high side current sense amplifier with
* 12-bit ADC interface.
*
* Copyright (C) 2017 Jacopo Mondi
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
/*
* This driver supports input common-mode voltage, current-sense
* amplifier with programmable gains and die temperature reading from
* Maxim max9611/max9612.
*
* Op-amp, analog comparator, and watchdog functionalities are not
* supported by this driver.
*/
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/module.h>
#include <linux/of_device.h>
#define DRIVER_NAME "max9611"
/* max9611 register addresses */
#define MAX9611_REG_CSA_DATA 0x00
#define MAX9611_REG_RS_DATA 0x02
#define MAX9611_REG_TEMP_DATA 0x08
#define MAX9611_REG_CTRL1 0x0a
#define MAX9611_REG_CTRL2 0x0b
/* max9611 REG1 mux configuration options */
#define MAX9611_MUX_MASK GENMASK(3, 0)
#define MAX9611_MUX_SENSE_1x 0x00
#define MAX9611_MUX_SENSE_4x 0x01
#define MAX9611_MUX_SENSE_8x 0x02
#define MAX9611_INPUT_VOLT 0x03
#define MAX9611_MUX_TEMP 0x06
/* max9611 voltage (both csa and input) helper macros */
#define MAX9611_VOLTAGE_SHIFT 0x04
#define MAX9611_VOLTAGE_RAW(_r) ((_r) >> MAX9611_VOLTAGE_SHIFT)
/*
* max9611 current sense amplifier voltage output:
* LSB and offset values depends on selected gain (1x, 4x, 8x)
*
* GAIN LSB (nV) OFFSET (LSB steps)
* 1x 107500 1
* 4x 26880 1
* 8x 13440 3
*
* The complete formula to calculate current sense voltage is:
* (((adc_read >> 4) - offset) / ((1 / LSB) * 10^-3)
*/
#define MAX9611_CSA_1X_LSB_nV 107500
#define MAX9611_CSA_4X_LSB_nV 26880
#define MAX9611_CSA_8X_LSB_nV 13440
#define MAX9611_CSA_1X_OFFS_RAW 1
#define MAX9611_CSA_4X_OFFS_RAW 1
#define MAX9611_CSA_8X_OFFS_RAW 3
/*
* max9611 common input mode (CIM): LSB is 14mV, with 14mV offset at 25 C
*
* The complete formula to calculate input common voltage is:
* (((adc_read >> 4) * 1000) - offset) / (1 / 14 * 1000)
*/
#define MAX9611_CIM_LSB_mV 14
#define MAX9611_CIM_OFFSET_RAW 1
/*
* max9611 temperature reading: LSB is 480 milli degrees Celsius
*
* The complete formula to calculate temperature is:
* ((adc_read >> 7) * 1000) / (1 / 480 * 1000)
*/
#define MAX9611_TEMP_MAX_POS 0x7f80
#define MAX9611_TEMP_MAX_NEG 0xff80
#define MAX9611_TEMP_MIN_NEG 0xd980
#define MAX9611_TEMP_MASK GENMASK(7, 15)
#define MAX9611_TEMP_SHIFT 0x07
#define MAX9611_TEMP_RAW(_r) ((_r) >> MAX9611_TEMP_SHIFT)
#define MAX9611_TEMP_SCALE_NUM 1000000
#define MAX9611_TEMP_SCALE_DIV 2083
struct max9611_dev {
struct device *dev;
struct i2c_client *i2c_client;
struct mutex lock;
unsigned int shunt_resistor_uohm;
};
enum max9611_conf_ids {
CONF_SENSE_1x,
CONF_SENSE_4x,
CONF_SENSE_8x,
CONF_IN_VOLT,
CONF_TEMP,
};
/**
* max9611_mux_conf - associate ADC mux configuration with register address
* where data shall be read from
*/
static const unsigned int max9611_mux_conf[][2] = {
/* CONF_SENSE_1x */
{ MAX9611_MUX_SENSE_1x, MAX9611_REG_CSA_DATA },
/* CONF_SENSE_4x */
{ MAX9611_MUX_SENSE_4x, MAX9611_REG_CSA_DATA },
/* CONF_SENSE_8x */
{ MAX9611_MUX_SENSE_8x, MAX9611_REG_CSA_DATA },
/* CONF_IN_VOLT */
{ MAX9611_INPUT_VOLT, MAX9611_REG_RS_DATA },
/* CONF_TEMP */
{ MAX9611_MUX_TEMP, MAX9611_REG_TEMP_DATA },
};
enum max9611_csa_gain {
CSA_GAIN_1x,
CSA_GAIN_4x,
CSA_GAIN_8x,
};
enum max9611_csa_gain_params {
CSA_GAIN_LSB_nV,
CSA_GAIN_OFFS_RAW,
};
/**
* max9611_csa_gain_conf - associate gain multiplier with LSB and
* offset values.
*
* Group together parameters associated with configurable gain
* on current sense amplifier path to ADC interface.
* Current sense read routine adjusts gain until it gets a meaningful
* value; use this structure to retrieve the correct LSB and offset values.
*/
static const unsigned int max9611_gain_conf[][2] = {
{ /* [0] CSA_GAIN_1x */
MAX9611_CSA_1X_LSB_nV,
MAX9611_CSA_1X_OFFS_RAW,
},
{ /* [1] CSA_GAIN_4x */
MAX9611_CSA_4X_LSB_nV,
MAX9611_CSA_4X_OFFS_RAW,
},
{ /* [2] CSA_GAIN_8x */
MAX9611_CSA_8X_LSB_nV,
MAX9611_CSA_8X_OFFS_RAW,
},
};
enum max9611_chan_addrs {
MAX9611_CHAN_VOLTAGE_INPUT,
MAX9611_CHAN_VOLTAGE_SENSE,
MAX9611_CHAN_TEMPERATURE,
MAX9611_CHAN_CURRENT_LOAD,
MAX9611_CHAN_POWER_LOAD,
};
static const struct iio_chan_spec max9611_channels[] = {
{
.type = IIO_TEMP,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
BIT(IIO_CHAN_INFO_SCALE),
.address = MAX9611_CHAN_TEMPERATURE,
},
{
.type = IIO_VOLTAGE,
.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
.address = MAX9611_CHAN_VOLTAGE_SENSE,
.indexed = 1,
.channel = 0,
},
{
.type = IIO_VOLTAGE,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
BIT(IIO_CHAN_INFO_SCALE) |
BIT(IIO_CHAN_INFO_OFFSET),
.address = MAX9611_CHAN_VOLTAGE_INPUT,
.indexed = 1,
.channel = 1,
},
{
.type = IIO_CURRENT,
.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
.address = MAX9611_CHAN_CURRENT_LOAD,
},
{
.type = IIO_POWER,
.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
.address = MAX9611_CHAN_POWER_LOAD
},
};
/**
* max9611_read_single() - read a single value from ADC interface
*
* Data registers are 16 bit long, spread between two 8 bit registers
* with consecutive addresses.
* Configure ADC mux first, then read register at address "reg_addr".
* The smbus_read_word routine asks for 16 bits and the ADC is kind enough
* to return values from "reg_addr" and "reg_addr + 1" consecutively.
* Data are transmitted with big-endian ordering: MSB arrives first.
*
* @max9611: max9611 device
* @selector: index for mux and register configuration
* @raw_val: the value returned from ADC
*/
static int max9611_read_single(struct max9611_dev *max9611,
enum max9611_conf_ids selector,
u16 *raw_val)
{
int ret;
u8 mux_conf = max9611_mux_conf[selector][0] & MAX9611_MUX_MASK;
u8 reg_addr = max9611_mux_conf[selector][1];
/*
* Keep mutex lock held during read-write to avoid mux register
* (CTRL1) re-configuration.
*/
mutex_lock(&max9611->lock);
ret = i2c_smbus_write_byte_data(max9611->i2c_client,
MAX9611_REG_CTRL1, mux_conf);
if (ret) {
dev_err(max9611->dev, "i2c write byte failed: 0x%2x - 0x%2x\n",
MAX9611_REG_CTRL1, mux_conf);
mutex_unlock(&max9611->lock);
return ret;
}
/*
* need a delay here to make register configuration
* stabilize. 1 msec at least, from empirical testing.
*/
usleep_range(1000, 2000);
ret = i2c_smbus_read_word_swapped(max9611->i2c_client, reg_addr);
if (ret < 0) {
dev_err(max9611->dev, "i2c read word from 0x%2x failed\n",
reg_addr);
mutex_unlock(&max9611->lock);
return ret;
}
*raw_val = ret;
mutex_unlock(&max9611->lock);
return 0;
}
/**
* max9611_read_csa_voltage() - read current sense amplifier output voltage
*
* Current sense amplifier output voltage is read through a configurable
* 1x, 4x or 8x gain.
* Start with plain 1x gain, and adjust gain control properly until a
* meaningful value is read from ADC output.
*
* @max9611: max9611 device
* @adc_raw: raw value read from ADC output
* @csa_gain: gain configuration option selector
*/
static int max9611_read_csa_voltage(struct max9611_dev *max9611,
u16 *adc_raw,
enum max9611_csa_gain *csa_gain)
{
enum max9611_conf_ids gain_selectors[] = {
CONF_SENSE_1x,
CONF_SENSE_4x,
CONF_SENSE_8x
};
unsigned int i;
int ret;
for (i = 0; i < ARRAY_SIZE(gain_selectors); ++i) {
ret = max9611_read_single(max9611, gain_selectors[i], adc_raw);
if (ret)
return ret;
if (*adc_raw > 0) {
*csa_gain = gain_selectors[i];
return 0;
}
}
return -EIO;
}
static int max9611_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val, int *val2, long mask)
{
struct max9611_dev *dev = iio_priv(indio_dev);
enum max9611_csa_gain gain_selector;
const unsigned int *csa_gain;
u16 adc_data;
int ret;
switch (mask) {
case IIO_CHAN_INFO_RAW:
switch (chan->address) {
case MAX9611_CHAN_TEMPERATURE:
ret = max9611_read_single(dev, CONF_TEMP,
&adc_data);
if (ret)
return -EINVAL;
*val = MAX9611_TEMP_RAW(adc_data);
return IIO_VAL_INT;
case MAX9611_CHAN_VOLTAGE_INPUT:
ret = max9611_read_single(dev, CONF_IN_VOLT,
&adc_data);
if (ret)
return -EINVAL;
*val = MAX9611_VOLTAGE_RAW(adc_data);
return IIO_VAL_INT;
}
break;
case IIO_CHAN_INFO_OFFSET:
/* MAX9611_CHAN_VOLTAGE_INPUT */
*val = MAX9611_CIM_OFFSET_RAW;
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
switch (chan->address) {
case MAX9611_CHAN_TEMPERATURE:
*val = MAX9611_TEMP_SCALE_NUM;
*val2 = MAX9611_TEMP_SCALE_DIV;
return IIO_VAL_FRACTIONAL;
case MAX9611_CHAN_VOLTAGE_INPUT:
*val = MAX9611_CIM_LSB_mV;
return IIO_VAL_INT;
}
break;
case IIO_CHAN_INFO_PROCESSED:
switch (chan->address) {
case MAX9611_CHAN_VOLTAGE_SENSE:
/*
* processed (mV): (raw - offset) * LSB (nV) / 10^6
*
* Even if max9611 can output raw csa voltage readings,
* use a produced value as scale depends on gain.
*/
ret = max9611_read_csa_voltage(dev, &adc_data,
&gain_selector);
if (ret)
return -EINVAL;
csa_gain = max9611_gain_conf[gain_selector];
adc_data -= csa_gain[CSA_GAIN_OFFS_RAW];
*val = MAX9611_VOLTAGE_RAW(adc_data) *
csa_gain[CSA_GAIN_LSB_nV];
*val2 = 1000000;
return IIO_VAL_FRACTIONAL;
case MAX9611_CHAN_CURRENT_LOAD:
/* processed (mA): Vcsa (nV) / Rshunt (uOhm) */
ret = max9611_read_csa_voltage(dev, &adc_data,
&gain_selector);
if (ret)
return -EINVAL;
csa_gain = max9611_gain_conf[gain_selector];
adc_data -= csa_gain[CSA_GAIN_OFFS_RAW];
*val = MAX9611_VOLTAGE_RAW(adc_data) *
csa_gain[CSA_GAIN_LSB_nV];
*val2 = dev->shunt_resistor_uohm;
return IIO_VAL_FRACTIONAL;
case MAX9611_CHAN_POWER_LOAD:
/*
* processed (mW): Vin (mV) * Vcsa (uV) /
* Rshunt (uOhm)
*/
ret = max9611_read_single(dev, CONF_IN_VOLT,
&adc_data);
if (ret)
return -EINVAL;
adc_data -= MAX9611_CIM_OFFSET_RAW;
*val = MAX9611_VOLTAGE_RAW(adc_data) *
MAX9611_CIM_LSB_mV;
ret = max9611_read_csa_voltage(dev, &adc_data,
&gain_selector);
if (ret)
return -EINVAL;
csa_gain = max9611_gain_conf[gain_selector];
/* divide by 10^3 here to avoid 32bit overflow */
adc_data -= csa_gain[CSA_GAIN_OFFS_RAW];
*val *= MAX9611_VOLTAGE_RAW(adc_data) *
csa_gain[CSA_GAIN_LSB_nV] / 1000;
*val2 = dev->shunt_resistor_uohm;
return IIO_VAL_FRACTIONAL;
}
break;
}
return -EINVAL;
}
static ssize_t max9611_shunt_resistor_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
struct max9611_dev *max9611 = iio_priv(dev_to_iio_dev(dev));
unsigned int i, r;
i = max9611->shunt_resistor_uohm / 1000000;
r = max9611->shunt_resistor_uohm % 1000000;
return sprintf(buf, "%u.%06u\n", i, r);
}
static IIO_DEVICE_ATTR(in_power_shunt_resistor, 0444,
max9611_shunt_resistor_show, NULL, 0);
static IIO_DEVICE_ATTR(in_current_shunt_resistor, 0444,
max9611_shunt_resistor_show, NULL, 0);
static struct attribute *max9611_attributes[] = {
&iio_dev_attr_in_power_shunt_resistor.dev_attr.attr,
&iio_dev_attr_in_current_shunt_resistor.dev_attr.attr,
NULL,
};
static const struct attribute_group max9611_attribute_group = {
.attrs = max9611_attributes,
};
static const struct iio_info indio_info = {
.read_raw = max9611_read_raw,
.attrs = &max9611_attribute_group,
};
static int max9611_init(struct max9611_dev *max9611)
{
struct i2c_client *client = max9611->i2c_client;
u16 regval;
int ret;
if (!i2c_check_functionality(client->adapter,
I2C_FUNC_SMBUS_WRITE_BYTE |
I2C_FUNC_SMBUS_READ_WORD_DATA)) {
dev_err(max9611->dev,
"I2c adapter does not support smbus write_byte or read_word functionalities: aborting probe.\n");
return -EINVAL;
}
/* Make sure die temperature is in range to test communications. */
ret = max9611_read_single(max9611, CONF_TEMP, &regval);
if (ret)
return ret;
regval = ret & MAX9611_TEMP_MASK;
if ((regval > MAX9611_TEMP_MAX_POS &&
regval < MAX9611_TEMP_MIN_NEG) ||
regval > MAX9611_TEMP_MAX_NEG) {
dev_err(max9611->dev,
"Invalid value received from ADC 0x%4x: aborting\n",
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(1000, 2000);
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";
const struct device_node *of_node = client->dev.of_node;
const struct of_device_id *of_id =
of_match_device(max9611_of_table, &client->dev);
struct max9611_dev *max9611;
struct iio_dev *indio_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 = &client->dev;
max9611->i2c_client = client;
mutex_init(&max9611->lock);
ret = of_property_read_u32(of_node, shunt_res_prop, &of_shunt);
if (ret) {
dev_err(&client->dev,
"Missing %s property for %pOF node\n",
shunt_res_prop, of_node);
return ret;
}
max9611->shunt_resistor_uohm = of_shunt;
ret = max9611_init(max9611);
if (ret)
return ret;
indio_dev->dev.parent = &client->dev;
indio_dev->dev.of_node = client->dev.of_node;
indio_dev->name = of_id->data;
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(&client->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");
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