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

Mike Looijmans
2023-03-07T06:57:07Z

The ADS1100 is a 16-bit ADC (at 8 samples per second).
The ADS1000 is similar, but has a fixed data rate.

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));
+ }
+
+ 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

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