--- /dev/null
+/*
+ * 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 / 1000;
+ r = max9611->shunt_resistor_uohm % 1000;
+
+ return sprintf(buf, "%u.%03u\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 = {
+ .driver_module = THIS_MODULE,
+ .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 = 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 (IS_ERR(indio_dev))
+ return PTR_ERR(indio_dev);
+
+ 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 %s node\n",
+ shunt_res_prop, of_node->full_name);
+ 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,
+ .owner = THIS_MODULE,
+ .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");
projects / GitHub / LineageOS / android_kernel_motorola_exynos9610.git / commitdiff