Re: [PATCH v5 2/2] iio: adc: Add TI ADS1100 and ADS1000

Andy Shevchenko
2023-03-07T12:24:57Z

On Tue, Mar 07, 2023 at 07:55:34AM +0100, Mike Looijmans wrote:
> The ADS1100 is a 16-bit ADC (at 8 samples per second).
> The ADS1000 is similar, but has a fixed data rate.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

But see below.

> Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
>
> ---
>
> Changes in v5:
> Use scripts/Lindent to auto-format
> Use DIV_ROUNDUP_CLOSEST in gain calculation
>
> Changes in v4:
> Use post-increment
> Formatting fixes (commas, indents, empty line)
> Use 'ffs' and explain gain formula
> Use dev_set_drvdata/dev_get_drvdata for pm_ methods
> Use units.h for micro-to-milli conversion
>
> Changes in v3:
> Add #include linux/bitfield.h and linux/bits.h
>
> Changes in v2:
> Remove "driver for" from title
> Use proper PM_RUNTIME macros
> Fix indents
> Use dev_err_probe()
> Unsigned index and post-increment
> Use GENMASK and FIELD_GET
> remove ads1100_set_conv_mode
> remove Kconfig BUFFER dependencies
> remove unused #include
> Set SCALE instead of HARDWAREGAIN
> Use devm_add_action_or_reset
>
> drivers/iio/adc/Kconfig | 10 +
> drivers/iio/adc/Makefile | 1 +
> drivers/iio/adc/ti-ads1100.c | 444 +++++++++++++++++++++++++++++++++++
> 3 files changed, 455 insertions(+)
> create mode 100644 drivers/iio/adc/ti-ads1100.c
>
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 63f80d747cbd..257efb25a92e 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -1207,6 +1207,16 @@ config TI_ADS1015
> This driver can also be built as a module. If so, the module will be
> called ti-ads1015.
>
> +config TI_ADS1100
> + tristate "Texas Instruments ADS1100 and ADS1000 ADC"
> + depends on I2C
> + help
> + If you say yes here you get support for Texas Instruments ADS1100 and
> + ADS1000 ADC chips.
> +
> + This driver can also be built as a module. If so, the module will be
> + called ti-ads1100.
> +
> config TI_ADS7950
> tristate "Texas Instruments ADS7950 ADC driver"
> depends on SPI && GPIOLIB
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index 4ef41a7dfac6..61ef600fab99 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -107,6 +107,7 @@ obj-$(CONFIG_TI_ADC108S102) += ti-adc108s102.o
> obj-$(CONFIG_TI_ADC128S052) += ti-adc128s052.o
> obj-$(CONFIG_TI_ADC161S626) += ti-adc161s626.o
> obj-$(CONFIG_TI_ADS1015) += ti-ads1015.o
> +obj-$(CONFIG_TI_ADS1100) += ti-ads1100.o
> obj-$(CONFIG_TI_ADS7950) += ti-ads7950.o
> obj-$(CONFIG_TI_ADS8344) += ti-ads8344.o
> obj-$(CONFIG_TI_ADS8688) += ti-ads8688.o
> diff --git a/drivers/iio/adc/ti-ads1100.c b/drivers/iio/adc/ti-ads1100.c
> new file mode 100644
> index 000000000000..ce386c18618f
> --- /dev/null
> +++ b/drivers/iio/adc/ti-ads1100.c
> @@ -0,0 +1,444 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * ADS1100 - Texas Instruments Analog-to-Digital Converter
> + *
> + * Copyright (c) 2023, Topic Embedded Products
> + *
> + * Datasheet: https://www.ti.com/lit/gpn/ads1100
> + * IIO driver for ADS1100 and ADS1000 ADC 16-bit I2C
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/bits.h>
> +#include <linux/delay.h>
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/i2c.h>
> +#include <linux/mutex.h>
> +#include <linux/property.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/units.h>
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/types.h>
> +
> +/* The ADS1100 has a single byte config register */
> +
> +/* Conversion in progress bit */
> +#define ADS1100_CFG_ST_BSY BIT(7)
> +/* Single conversion bit */
> +#define ADS1100_CFG_SC BIT(4)
> +/* Data rate */
> +#define ADS1100_DR_MASK GENMASK(3, 2)
> +/* Gain */
> +#define ADS1100_PGA_MASK GENMASK(1, 0)
> +
> +#define ADS1100_CONTINUOUS 0
> +#define ADS1100_SINGLESHOT ADS1100_CFG_SC
> +
> +#define ADS1100_SLEEP_DELAY_MS 2000
> +
> +static const int ads1100_data_rate[] = { 128, 32, 16, 8 };
> +static const int ads1100_data_rate_bits[] = { 12, 14, 15, 16 };
> +
> +struct ads1100_data {
> + struct i2c_client *client;
> + struct regulator *reg_vdd;
> + struct mutex lock;
> + int scale_avail[2 * 4]; /* 4 gain settings */
> + u8 config;
> + bool supports_data_rate; /* Only the ADS1100 can select the rate */
> +};
> +
> +static const struct iio_chan_spec ads1100_channel = {
> + .type = IIO_VOLTAGE,
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> + .info_mask_shared_by_all =
> + BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_SAMP_FREQ),
> + .info_mask_shared_by_all_available =
> + BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_SAMP_FREQ),
> + .scan_type = {
> + .sign = 's',
> + .realbits = 16,
> + .storagebits = 16,
> + .endianness = IIO_CPU,
> + },
> + .datasheet_name = "AIN",
> +};
> +
> +static int ads1100_set_config_bits(struct ads1100_data *data, u8 mask, u8 value)
> +{
> + int ret;
> + u8 config = (data->config & ~mask) | (value & mask);
> +
> + if (data->config == config)
> + return 0; /* Already done */
> +
> + ret = i2c_master_send(data->client, &config, 1);
> + if (ret < 0)
> + return ret;
> +
> + data->config = config;
> + return 0;
> +};
> +
> +static int ads1100_data_bits(struct ads1100_data *data)
> +{
> + return ads1100_data_rate_bits[FIELD_GET(ADS1100_DR_MASK, data->config)];
> +}
> +
> +static int ads1100_get_adc_result(struct ads1100_data *data, int chan, int *val)
> +{
> + int ret;
> + __be16 buffer;
> + s16 value;
> +
> + if (chan != 0)
> + return -EINVAL;
> +
> + ret = pm_runtime_resume_and_get(&data->client->dev);
> + if (ret < 0)
> + return ret;
> +
> + ret = i2c_master_recv(data->client, (char *)&buffer, sizeof(buffer));
> +
> + pm_runtime_mark_last_busy(&data->client->dev);
> + pm_runtime_put_autosuspend(&data->client->dev);
> +
> + if (ret < 0) {
> + dev_err(&data->client->dev, "I2C read fail: %d\n", ret);
> + return ret;
> + }
> +
> + /* Value is always 16-bit 2's complement */
> + value = be16_to_cpu(buffer);
> +
> + /* Shift result to compensate for bit resolution vs. sample rate */
> + value <<= 16 - ads1100_data_bits(data);
> +
> + *val = sign_extend32(value, 15);
> +
> + return 0;
> +}
> +
> +static int ads1100_set_scale(struct ads1100_data *data, int val, int val2)
> +{
> + int microvolts;
> + int gain;
> +
> + /* With Vdd between 2.7 and 5V, the scale is always below 1 */
> + if (val)
> + return -EINVAL;
> +
> + if (!val2)
> + return -EINVAL;
> +
> + microvolts = regulator_get_voltage(data->reg_vdd);
> + /*
> + * val2 is in 'micro' units, n = val2 / 1000000
> + * result must be millivolts, d = microvolts / 1000
> + * the full-scale value is d/n, corresponds to 2^15,
> + * hence the gain = (d / n) >> 15, factoring out the 1000 and moving the
> + * bitshift so everything fits in 32-bits yields this formula.
> + */
> + gain = DIV_ROUND_CLOSEST(microvolts, BIT(15)) * MILLI / val2;
> + if (gain < BIT(0) || gain > BIT(3))
> + return -EINVAL;
> +
> + ads1100_set_config_bits(data, ADS1100_PGA_MASK, ffs(gain) - 1);
> + return 0;
> +}
> +
> +static int ads1100_set_data_rate(struct ads1100_data *data, int chan, int rate)
> +{
> + unsigned int i;
> + unsigned int size;
> +
> + size = data->supports_data_rate ? ARRAY_SIZE(ads1100_data_rate) : 1;
> + for (i = 0; i < size; i++) {
> + if (ads1100_data_rate[i] == rate)
> + return ads1100_set_config_bits(data, ADS1100_DR_MASK,

> + FIELD_PREP
> + (ADS1100_DR_MASK, i));

This is better on a single line.

> + }
> +
> + return -EINVAL;
> +}
> +
> +static int ads1100_get_vdd_millivolts(struct ads1100_data *data)
> +{
> + return regulator_get_voltage(data->reg_vdd) / (MICRO / MILLI);
> +}
> +
> +static void ads1100_calc_scale_avail(struct ads1100_data *data)
> +{
> + int millivolts = ads1100_get_vdd_millivolts(data);
> + unsigned int i;
> +
> + for (i = 0; i < ARRAY_SIZE(data->scale_avail) / 2; i++) {
> + data->scale_avail[i * 2 + 0] = millivolts;
> + data->scale_avail[i * 2 + 1] = 15 + i;
> + }
> +}
> +
> +static int ads1100_read_avail(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + const int **vals, int *type, int *length,
> + long mask)
> +{
> + struct ads1100_data *data = iio_priv(indio_dev);
> +
> + if (chan->type != IIO_VOLTAGE)
> + return -EINVAL;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_SAMP_FREQ:
> + *type = IIO_VAL_INT;
> + *vals = ads1100_data_rate;
> + if (data->supports_data_rate)
> + *length = ARRAY_SIZE(ads1100_data_rate);
> + else
> + *length = 1;
> + return IIO_AVAIL_LIST;
> + case IIO_CHAN_INFO_SCALE:
> + *type = IIO_VAL_FRACTIONAL_LOG2;
> + *vals = data->scale_avail;
> + *length = ARRAY_SIZE(data->scale_avail);
> + return IIO_AVAIL_LIST;
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static int ads1100_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan, int *val,
> + int *val2, long mask)
> +{
> + int ret;
> + struct ads1100_data *data = iio_priv(indio_dev);
> +
> + mutex_lock(&data->lock);
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + ret = iio_device_claim_direct_mode(indio_dev);
> + if (ret)
> + break;
> +
> + ret = ads1100_get_adc_result(data, chan->address, val);
> + if (ret >= 0)
> + ret = IIO_VAL_INT;
> + iio_device_release_direct_mode(indio_dev);
> + break;
> + case IIO_CHAN_INFO_SCALE:
> + /* full-scale is the supply voltage in millivolts */
> + *val = ads1100_get_vdd_millivolts(data);
> + *val2 = 15 + FIELD_GET(ADS1100_PGA_MASK, data->config);
> + ret = IIO_VAL_FRACTIONAL_LOG2;
> + break;
> + case IIO_CHAN_INFO_SAMP_FREQ:
> + *val = ads1100_data_rate[FIELD_GET(ADS1100_DR_MASK,
> + data->config)];
> + ret = IIO_VAL_INT;
> + break;
> + default:
> + ret = -EINVAL;
> + break;
> + }
> + mutex_unlock(&data->lock);
> +
> + return ret;
> +}
> +
> +static int ads1100_write_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan, int val,
> + int val2, long mask)
> +{
> + struct ads1100_data *data = iio_priv(indio_dev);
> + int ret;
> +
> + mutex_lock(&data->lock);
> + switch (mask) {
> + case IIO_CHAN_INFO_SCALE:
> + ret = ads1100_set_scale(data, val, val2);
> + break;
> + case IIO_CHAN_INFO_SAMP_FREQ:
> + ret = ads1100_set_data_rate(data, chan->address, val);
> + break;
> + default:
> + ret = -EINVAL;
> + break;
> + }
> + mutex_unlock(&data->lock);
> +
> + return ret;
> +}
> +
> +static const struct iio_info ads1100_info = {
> + .read_avail = ads1100_read_avail,
> + .read_raw = ads1100_read_raw,
> + .write_raw = ads1100_write_raw,
> +};
> +
> +static int ads1100_setup(struct ads1100_data *data)
> +{
> + int ret;
> + u8 buffer[3];
> +
> + /* Setup continuous sampling mode at 8sps */
> + buffer[0] = ADS1100_DR_MASK | ADS1100_CONTINUOUS;
> + ret = i2c_master_send(data->client, buffer, 1);
> + if (ret < 0)
> + return ret;
> +
> + ret = i2c_master_recv(data->client, buffer, sizeof(buffer));
> + if (ret < 0)
> + return ret;
> +
> + /* Config register returned in third byte, strip away the busy status */
> + data->config = buffer[2] & ~ADS1100_CFG_ST_BSY;
> +
> + /* Detect the sample rate capability by checking the DR bits */
> + data->supports_data_rate = FIELD_GET(ADS1100_DR_MASK, buffer[2]) != 0;
> +
> + return 0;
> +}
> +
> +static void ads1100_reg_disable(void *reg)
> +{
> + regulator_disable(reg);
> +}
> +
> +static void ads1100_disable_continuous(void *data)
> +{
> + ads1100_set_config_bits(data, ADS1100_CFG_SC, ADS1100_SINGLESHOT);
> +}
> +
> +static int ads1100_probe(struct i2c_client *client)
> +{
> + struct iio_dev *indio_dev;
> + struct ads1100_data *data;
> + struct device *dev = &client->dev;
> + int ret;
> +
> + indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
> + if (!indio_dev)
> + return -ENOMEM;
> +
> + data = iio_priv(indio_dev);
> + dev_set_drvdata(dev, data);
> + data->client = client;
> + mutex_init(&data->lock);
> +
> + indio_dev->name = "ads1100";
> + indio_dev->modes = INDIO_DIRECT_MODE;
> + indio_dev->channels = &ads1100_channel;
> + indio_dev->num_channels = 1;
> + indio_dev->info = &ads1100_info;
> +
> + data->reg_vdd = devm_regulator_get(dev, "vdd");
> + if (IS_ERR(data->reg_vdd))
> + return dev_err_probe(dev, PTR_ERR(data->reg_vdd),
> + "Failed to get vdd regulator\n");
> +
> + ret = regulator_enable(data->reg_vdd);
> + if (ret < 0)
> + return dev_err_probe(dev, PTR_ERR(data->reg_vdd),
> + "Failed to enable vdd regulator\n");
> +
> + ret = devm_add_action_or_reset(dev, ads1100_reg_disable, data->reg_vdd);
> + if (ret)
> + return ret;
> +
> + ret = ads1100_setup(data);
> + if (ret)
> + return dev_err_probe(dev, ret,
> + "Failed to communicate with device\n");
> +
> + ret = devm_add_action_or_reset(dev, ads1100_disable_continuous, data);
> + if (ret)
> + return ret;
> +
> + ads1100_calc_scale_avail(data);
> +
> + pm_runtime_set_autosuspend_delay(dev, ADS1100_SLEEP_DELAY_MS);
> + pm_runtime_use_autosuspend(dev);
> + pm_runtime_set_active(dev);
> + ret = devm_pm_runtime_enable(dev);
> + if (ret)
> + return dev_err_probe(dev, ret, "Failed to enable pm_runtime\n");
> +
> + ret = devm_iio_device_register(dev, indio_dev);
> + if (ret)
> + return dev_err_probe(dev, ret,
> + "Failed to register IIO device\n");
> +
> + return 0;
> +}
> +
> +static int ads1100_runtime_suspend(struct device *dev)
> +{
> + struct ads1100_data *data = dev_get_drvdata(dev);
> +
> + ads1100_set_config_bits(data, ADS1100_CFG_SC, ADS1100_SINGLESHOT);
> + regulator_disable(data->reg_vdd);
> +
> + return 0;
> +}
> +
> +static int ads1100_runtime_resume(struct device *dev)
> +{
> + struct ads1100_data *data = dev_get_drvdata(dev);
> + int ret;
> +
> + ret = regulator_enable(data->reg_vdd);
> + if (ret) {
> + dev_err(&data->client->dev, "Failed to enable Vdd\n");
> + return ret;
> + }
> +
> + /*
> + * We'll always change the mode bit in the config register, so there is
> + * no need here to "force" a write to the config register. If the device
> + * has been power-cycled, we'll re-write its config register now.
> + */
> + return ads1100_set_config_bits(data, ADS1100_CFG_SC,
> + ADS1100_CONTINUOUS);
> +}
> +
> +static DEFINE_RUNTIME_DEV_PM_OPS(ads1100_pm_ops,
> + ads1100_runtime_suspend,
> + ads1100_runtime_resume,
> + NULL);
> +
> +static const struct i2c_device_id ads1100_id[] = {
> + { "ads1100" },
> + { "ads1000" },
> + { }
> +};
> +
> +MODULE_DEVICE_TABLE(i2c, ads1100_id);
> +
> +static const struct of_device_id ads1100_of_match[] = {
> + {.compatible = "ti,ads1100" },
> + {.compatible = "ti,ads1000" },
> + { }
> +};
> +
> +MODULE_DEVICE_TABLE(of, ads1100_of_match);
> +
> +static struct i2c_driver ads1100_driver = {
> + .driver = {
> + .name = "ads1100",
> + .of_match_table = ads1100_of_match,
> + .pm = pm_ptr(&ads1100_pm_ops),
> + },
> + .probe_new = ads1100_probe,
> + .id_table = ads1100_id,
> +};
> +
> +module_i2c_driver(ads1100_driver);
> +
> +MODULE_AUTHOR("Mike Looijmans <mike.looijmans@topic.nl>");
> +MODULE_DESCRIPTION("Texas Instruments ADS1100 ADC driver");
> +MODULE_LICENSE("GPL");
> --
> 2.17.1
>
>
> Met vriendelijke groet / kind regards,
>
> Mike Looijmans
> System Expert
>
>
> TOPIC Embedded Products B.V.
> Materiaalweg 4, 5681 RJ Best
> The Netherlands
>
> T: +31 (0) 499 33 69 69
> E: mike.looijmans@topicproducts.com
> W: www.topic.nl
>
> Please consider the environment before printing this e-mail

--
With Best Regards,
Andy Shevchenko