diff options
Diffstat (limited to 'drivers/iio/adc/max9611.c')
| -rw-r--r-- | drivers/iio/adc/max9611.c | 587 |
1 files changed, 587 insertions, 0 deletions
diff --git a/drivers/iio/adc/max9611.c b/drivers/iio/adc/max9611.c new file mode 100644 index 000000000..9f1a5ef0b --- /dev/null +++ b/drivers/iio/adc/max9611.c @@ -0,0 +1,587 @@ +/* + * 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(15, 7) +#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 + +/* + * Conversion time is 2 ms (typically) at Ta=25 degreeC + * No maximum value is known, so play it safe. + */ +#define MAX9611_CONV_TIME_US_RANGE 3000, 3300 + +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. */ + + usleep_range(MAX9611_CONV_TIME_US_RANGE); + + 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 = (enum max9611_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, ®val); + if (ret) + return ret; + + regval &= 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(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"; + 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"); |