/* * 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 #include #include #include #include #include #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 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, ®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(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 "); MODULE_DESCRIPTION("Maxim max9611/12 current sense amplifier with 12bit ADC"); MODULE_LICENSE("GPL v2");