446 lines
11 KiB
C
446 lines
11 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* ADS1100 - Texas Instruments Analog-to-Digital Converter
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*
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* Copyright (c) 2023, Topic Embedded Products
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*
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* Datasheet: https://www.ti.com/lit/gpn/ads1100
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* IIO driver for ADS1100 and ADS1000 ADC 16-bit I2C
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*/
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#include <linux/bitfield.h>
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#include <linux/bits.h>
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#include <linux/delay.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/i2c.h>
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#include <linux/mutex.h>
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#include <linux/property.h>
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#include <linux/pm_runtime.h>
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#include <linux/regulator/consumer.h>
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#include <linux/units.h>
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#include <linux/iio/iio.h>
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#include <linux/iio/types.h>
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/* The ADS1100 has a single byte config register */
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/* Conversion in progress bit */
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#define ADS1100_CFG_ST_BSY BIT(7)
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/* Single conversion bit */
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#define ADS1100_CFG_SC BIT(4)
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/* Data rate */
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#define ADS1100_DR_MASK GENMASK(3, 2)
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/* Gain */
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#define ADS1100_PGA_MASK GENMASK(1, 0)
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#define ADS1100_CONTINUOUS 0
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#define ADS1100_SINGLESHOT ADS1100_CFG_SC
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#define ADS1100_SLEEP_DELAY_MS 2000
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static const int ads1100_data_rate[] = { 128, 32, 16, 8 };
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static const int ads1100_data_rate_bits[] = { 12, 14, 15, 16 };
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struct ads1100_data {
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struct i2c_client *client;
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struct regulator *reg_vdd;
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struct mutex lock;
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int scale_avail[2 * 4]; /* 4 gain settings */
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u8 config;
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bool supports_data_rate; /* Only the ADS1100 can select the rate */
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};
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static const struct iio_chan_spec ads1100_channel = {
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.type = IIO_VOLTAGE,
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.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
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.info_mask_shared_by_all =
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BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_SAMP_FREQ),
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.info_mask_shared_by_all_available =
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BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_SAMP_FREQ),
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.scan_type = {
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.sign = 's',
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.realbits = 16,
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.storagebits = 16,
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.endianness = IIO_CPU,
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},
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.datasheet_name = "AIN",
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};
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static int ads1100_set_config_bits(struct ads1100_data *data, u8 mask, u8 value)
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{
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int ret;
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u8 config = (data->config & ~mask) | (value & mask);
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if (data->config == config)
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return 0; /* Already done */
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ret = i2c_master_send(data->client, &config, 1);
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if (ret < 0)
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return ret;
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data->config = config;
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return 0;
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};
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static int ads1100_data_bits(struct ads1100_data *data)
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{
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return ads1100_data_rate_bits[FIELD_GET(ADS1100_DR_MASK, data->config)];
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}
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static int ads1100_get_adc_result(struct ads1100_data *data, int chan, int *val)
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{
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int ret;
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__be16 buffer;
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s16 value;
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if (chan != 0)
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return -EINVAL;
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ret = pm_runtime_resume_and_get(&data->client->dev);
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if (ret < 0)
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return ret;
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ret = i2c_master_recv(data->client, (char *)&buffer, sizeof(buffer));
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pm_runtime_mark_last_busy(&data->client->dev);
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pm_runtime_put_autosuspend(&data->client->dev);
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if (ret < 0) {
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dev_err(&data->client->dev, "I2C read fail: %d\n", ret);
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return ret;
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}
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/* Value is always 16-bit 2's complement */
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value = be16_to_cpu(buffer);
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/* Shift result to compensate for bit resolution vs. sample rate */
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value <<= 16 - ads1100_data_bits(data);
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*val = sign_extend32(value, 15);
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return 0;
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}
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static int ads1100_set_scale(struct ads1100_data *data, int val, int val2)
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{
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int microvolts;
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int gain;
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/* With Vdd between 2.7 and 5V, the scale is always below 1 */
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if (val)
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return -EINVAL;
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if (!val2)
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return -EINVAL;
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microvolts = regulator_get_voltage(data->reg_vdd);
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/*
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* val2 is in 'micro' units, n = val2 / 1000000
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* result must be millivolts, d = microvolts / 1000
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* the full-scale value is d/n, corresponds to 2^15,
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* hence the gain = (d / n) >> 15, factoring out the 1000 and moving the
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* bitshift so everything fits in 32-bits yields this formula.
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*/
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gain = DIV_ROUND_CLOSEST(microvolts, BIT(15)) * MILLI / val2;
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if (gain < BIT(0) || gain > BIT(3))
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return -EINVAL;
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ads1100_set_config_bits(data, ADS1100_PGA_MASK, ffs(gain) - 1);
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return 0;
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}
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static int ads1100_set_data_rate(struct ads1100_data *data, int chan, int rate)
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{
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unsigned int i;
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unsigned int size;
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size = data->supports_data_rate ? ARRAY_SIZE(ads1100_data_rate) : 1;
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for (i = 0; i < size; i++) {
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if (ads1100_data_rate[i] == rate)
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return ads1100_set_config_bits(data, ADS1100_DR_MASK,
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FIELD_PREP(ADS1100_DR_MASK, i));
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}
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return -EINVAL;
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}
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static int ads1100_get_vdd_millivolts(struct ads1100_data *data)
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{
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return regulator_get_voltage(data->reg_vdd) / (MICRO / MILLI);
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}
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static void ads1100_calc_scale_avail(struct ads1100_data *data)
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{
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int millivolts = ads1100_get_vdd_millivolts(data);
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unsigned int i;
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for (i = 0; i < ARRAY_SIZE(data->scale_avail) / 2; i++) {
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data->scale_avail[i * 2 + 0] = millivolts;
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data->scale_avail[i * 2 + 1] = 15 + i;
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}
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}
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static int ads1100_read_avail(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan,
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const int **vals, int *type, int *length,
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long mask)
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{
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struct ads1100_data *data = iio_priv(indio_dev);
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if (chan->type != IIO_VOLTAGE)
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return -EINVAL;
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switch (mask) {
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case IIO_CHAN_INFO_SAMP_FREQ:
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*type = IIO_VAL_INT;
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*vals = ads1100_data_rate;
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if (data->supports_data_rate)
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*length = ARRAY_SIZE(ads1100_data_rate);
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else
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*length = 1;
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return IIO_AVAIL_LIST;
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case IIO_CHAN_INFO_SCALE:
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*type = IIO_VAL_FRACTIONAL_LOG2;
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*vals = data->scale_avail;
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*length = ARRAY_SIZE(data->scale_avail);
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return IIO_AVAIL_LIST;
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default:
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return -EINVAL;
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}
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}
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static int ads1100_read_raw(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan, int *val,
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int *val2, long mask)
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{
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int ret;
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struct ads1100_data *data = iio_priv(indio_dev);
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mutex_lock(&data->lock);
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switch (mask) {
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case IIO_CHAN_INFO_RAW:
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ret = iio_device_claim_direct_mode(indio_dev);
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if (ret)
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break;
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ret = ads1100_get_adc_result(data, chan->address, val);
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if (ret >= 0)
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ret = IIO_VAL_INT;
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iio_device_release_direct_mode(indio_dev);
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break;
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case IIO_CHAN_INFO_SCALE:
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/* full-scale is the supply voltage in millivolts */
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*val = ads1100_get_vdd_millivolts(data);
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*val2 = 15 + FIELD_GET(ADS1100_PGA_MASK, data->config);
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ret = IIO_VAL_FRACTIONAL_LOG2;
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break;
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case IIO_CHAN_INFO_SAMP_FREQ:
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*val = ads1100_data_rate[FIELD_GET(ADS1100_DR_MASK,
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data->config)];
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ret = IIO_VAL_INT;
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break;
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default:
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ret = -EINVAL;
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break;
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}
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mutex_unlock(&data->lock);
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return ret;
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}
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static int ads1100_write_raw(struct iio_dev *indio_dev,
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struct iio_chan_spec const *chan, int val,
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int val2, long mask)
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{
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struct ads1100_data *data = iio_priv(indio_dev);
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int ret;
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mutex_lock(&data->lock);
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switch (mask) {
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case IIO_CHAN_INFO_SCALE:
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ret = ads1100_set_scale(data, val, val2);
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break;
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case IIO_CHAN_INFO_SAMP_FREQ:
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ret = ads1100_set_data_rate(data, chan->address, val);
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break;
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default:
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ret = -EINVAL;
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break;
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}
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mutex_unlock(&data->lock);
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return ret;
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}
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static const struct iio_info ads1100_info = {
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.read_avail = ads1100_read_avail,
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.read_raw = ads1100_read_raw,
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.write_raw = ads1100_write_raw,
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};
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static int ads1100_setup(struct ads1100_data *data)
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{
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int ret;
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u8 buffer[3];
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/* Setup continuous sampling mode at 8sps */
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buffer[0] = ADS1100_DR_MASK | ADS1100_CONTINUOUS;
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ret = i2c_master_send(data->client, buffer, 1);
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if (ret < 0)
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return ret;
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ret = i2c_master_recv(data->client, buffer, sizeof(buffer));
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if (ret < 0)
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return ret;
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/* Config register returned in third byte, strip away the busy status */
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data->config = buffer[2] & ~ADS1100_CFG_ST_BSY;
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/* Detect the sample rate capability by checking the DR bits */
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data->supports_data_rate = FIELD_GET(ADS1100_DR_MASK, buffer[2]) != 0;
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return 0;
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}
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static void ads1100_reg_disable(void *reg)
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{
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regulator_disable(reg);
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}
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static void ads1100_disable_continuous(void *data)
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{
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ads1100_set_config_bits(data, ADS1100_CFG_SC, ADS1100_SINGLESHOT);
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}
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static int ads1100_probe(struct i2c_client *client)
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{
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struct iio_dev *indio_dev;
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struct ads1100_data *data;
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struct device *dev = &client->dev;
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int ret;
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indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
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if (!indio_dev)
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return -ENOMEM;
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data = iio_priv(indio_dev);
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dev_set_drvdata(dev, data);
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data->client = client;
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mutex_init(&data->lock);
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indio_dev->name = "ads1100";
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indio_dev->modes = INDIO_DIRECT_MODE;
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indio_dev->channels = &ads1100_channel;
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indio_dev->num_channels = 1;
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indio_dev->info = &ads1100_info;
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data->reg_vdd = devm_regulator_get(dev, "vdd");
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if (IS_ERR(data->reg_vdd))
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return dev_err_probe(dev, PTR_ERR(data->reg_vdd),
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"Failed to get vdd regulator\n");
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ret = regulator_enable(data->reg_vdd);
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if (ret < 0)
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return dev_err_probe(dev, ret,
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"Failed to enable vdd regulator\n");
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ret = devm_add_action_or_reset(dev, ads1100_reg_disable, data->reg_vdd);
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if (ret)
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return ret;
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ret = ads1100_setup(data);
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if (ret)
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return dev_err_probe(dev, ret,
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"Failed to communicate with device\n");
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ret = devm_add_action_or_reset(dev, ads1100_disable_continuous, data);
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if (ret)
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return ret;
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ads1100_calc_scale_avail(data);
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pm_runtime_set_autosuspend_delay(dev, ADS1100_SLEEP_DELAY_MS);
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pm_runtime_use_autosuspend(dev);
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pm_runtime_set_active(dev);
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ret = devm_pm_runtime_enable(dev);
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if (ret)
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return dev_err_probe(dev, ret, "Failed to enable pm_runtime\n");
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ret = devm_iio_device_register(dev, indio_dev);
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if (ret)
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return dev_err_probe(dev, ret,
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"Failed to register IIO device\n");
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return 0;
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}
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static int ads1100_runtime_suspend(struct device *dev)
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{
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struct ads1100_data *data = dev_get_drvdata(dev);
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ads1100_set_config_bits(data, ADS1100_CFG_SC, ADS1100_SINGLESHOT);
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regulator_disable(data->reg_vdd);
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return 0;
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}
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static int ads1100_runtime_resume(struct device *dev)
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{
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struct ads1100_data *data = dev_get_drvdata(dev);
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int ret;
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ret = regulator_enable(data->reg_vdd);
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if (ret) {
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dev_err(&data->client->dev, "Failed to enable Vdd\n");
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return ret;
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}
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/*
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* We'll always change the mode bit in the config register, so there is
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* no need here to "force" a write to the config register. If the device
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* has been power-cycled, we'll re-write its config register now.
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*/
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return ads1100_set_config_bits(data, ADS1100_CFG_SC,
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ADS1100_CONTINUOUS);
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}
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static DEFINE_RUNTIME_DEV_PM_OPS(ads1100_pm_ops,
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ads1100_runtime_suspend,
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ads1100_runtime_resume,
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NULL);
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static const struct i2c_device_id ads1100_id[] = {
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{ "ads1100" },
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{ "ads1000" },
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, ads1100_id);
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static const struct of_device_id ads1100_of_match[] = {
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{.compatible = "ti,ads1100" },
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{.compatible = "ti,ads1000" },
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{ }
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};
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MODULE_DEVICE_TABLE(of, ads1100_of_match);
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static struct i2c_driver ads1100_driver = {
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.driver = {
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.name = "ads1100",
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.of_match_table = ads1100_of_match,
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.pm = pm_ptr(&ads1100_pm_ops),
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},
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.probe = ads1100_probe,
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.id_table = ads1100_id,
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};
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module_i2c_driver(ads1100_driver);
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MODULE_AUTHOR("Mike Looijmans <mike.looijmans@topic.nl>");
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MODULE_DESCRIPTION("Texas Instruments ADS1100 ADC driver");
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MODULE_LICENSE("GPL");
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