diff options
Diffstat (limited to 'drivers/iio/adc/ltc2309.c')
| -rw-r--r-- | drivers/iio/adc/ltc2309.c | 246 |
1 files changed, 246 insertions, 0 deletions
diff --git a/drivers/iio/adc/ltc2309.c b/drivers/iio/adc/ltc2309.c new file mode 100644 index 000000000000..8b3a89c1b840 --- /dev/null +++ b/drivers/iio/adc/ltc2309.c @@ -0,0 +1,246 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * The LTC2309 is an 8-Channel, 12-Bit SAR ADC with an I2C Interface. + * + * Datasheet: + * https://www.analog.com/media/en/technical-documentation/data-sheets/2309fd.pdf + * + * Copyright (c) 2023, Liam Beguin <liambeguin@gmail.com> + */ +#include <linux/bitfield.h> +#include <linux/i2c.h> +#include <linux/iio/iio.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/regulator/consumer.h> + +#define LTC2309_ADC_RESOLUTION 12 + +#define LTC2309_DIN_CH_MASK GENMASK(7, 4) +#define LTC2309_DIN_SDN BIT(7) +#define LTC2309_DIN_OSN BIT(6) +#define LTC2309_DIN_S1 BIT(5) +#define LTC2309_DIN_S0 BIT(4) +#define LTC2309_DIN_UNI BIT(3) +#define LTC2309_DIN_SLEEP BIT(2) + +/** + * struct ltc2309 - internal device data structure + * @dev: Device reference + * @client: I2C reference + * @vref: External reference source + * @lock: Lock to serialize data access + * @vref_mv: Internal voltage reference + */ +struct ltc2309 { + struct device *dev; + struct i2c_client *client; + struct regulator *vref; + struct mutex lock; /* serialize data access */ + int vref_mv; +}; + +/* Order matches expected channel address, See datasheet Table 1. */ +enum ltc2309_channels { + LTC2309_CH0_CH1 = 0, + LTC2309_CH2_CH3, + LTC2309_CH4_CH5, + LTC2309_CH6_CH7, + LTC2309_CH1_CH0, + LTC2309_CH3_CH2, + LTC2309_CH5_CH4, + LTC2309_CH7_CH6, + LTC2309_CH0, + LTC2309_CH2, + LTC2309_CH4, + LTC2309_CH6, + LTC2309_CH1, + LTC2309_CH3, + LTC2309_CH5, + LTC2309_CH7, +}; + +#define LTC2309_CHAN(_chan, _addr) { \ + .type = IIO_VOLTAGE, \ + .indexed = 1, \ + .address = _addr, \ + .channel = _chan, \ + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ +} + +#define LTC2309_DIFF_CHAN(_chan, _chan2, _addr) { \ + .type = IIO_VOLTAGE, \ + .differential = 1, \ + .indexed = 1, \ + .address = _addr, \ + .channel = _chan, \ + .channel2 = _chan2, \ + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ +} + +static const struct iio_chan_spec ltc2309_channels[] = { + LTC2309_CHAN(0, LTC2309_CH0), + LTC2309_CHAN(1, LTC2309_CH1), + LTC2309_CHAN(2, LTC2309_CH2), + LTC2309_CHAN(3, LTC2309_CH3), + LTC2309_CHAN(4, LTC2309_CH4), + LTC2309_CHAN(5, LTC2309_CH5), + LTC2309_CHAN(6, LTC2309_CH6), + LTC2309_CHAN(7, LTC2309_CH7), + LTC2309_DIFF_CHAN(0, 1, LTC2309_CH0_CH1), + LTC2309_DIFF_CHAN(2, 3, LTC2309_CH2_CH3), + LTC2309_DIFF_CHAN(4, 5, LTC2309_CH4_CH5), + LTC2309_DIFF_CHAN(6, 7, LTC2309_CH6_CH7), + LTC2309_DIFF_CHAN(1, 0, LTC2309_CH1_CH0), + LTC2309_DIFF_CHAN(3, 2, LTC2309_CH3_CH2), + LTC2309_DIFF_CHAN(5, 4, LTC2309_CH5_CH4), + LTC2309_DIFF_CHAN(7, 6, LTC2309_CH7_CH6), +}; + +static int ltc2309_read_raw_channel(struct ltc2309 *ltc2309, + unsigned long address, int *val) +{ + int ret; + u16 buf; + u8 din; + + din = FIELD_PREP(LTC2309_DIN_CH_MASK, address & 0x0f) | + FIELD_PREP(LTC2309_DIN_UNI, 1) | + FIELD_PREP(LTC2309_DIN_SLEEP, 0); + + ret = i2c_smbus_write_byte(ltc2309->client, din); + if (ret < 0) { + dev_err(ltc2309->dev, "i2c command failed: %pe\n", + ERR_PTR(ret)); + return ret; + } + + ret = i2c_master_recv(ltc2309->client, (char *)&buf, 2); + if (ret < 0) { + dev_err(ltc2309->dev, "i2c read failed: %pe\n", ERR_PTR(ret)); + return ret; + } + + *val = be16_to_cpu(buf) >> 4; + + return ret; +} + +static int ltc2309_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, int *val, + int *val2, long mask) +{ + struct ltc2309 *ltc2309 = iio_priv(indio_dev); + int ret; + + switch (mask) { + case IIO_CHAN_INFO_RAW: + mutex_lock(<c2309->lock); + ret = ltc2309_read_raw_channel(ltc2309, chan->address, val); + mutex_unlock(<c2309->lock); + if (ret < 0) + return -EINVAL; + return IIO_VAL_INT; + case IIO_CHAN_INFO_SCALE: + *val = ltc2309->vref_mv; + *val2 = LTC2309_ADC_RESOLUTION; + return IIO_VAL_FRACTIONAL_LOG2; + default: + return -EINVAL; + } +} + +static const struct iio_info ltc2309_info = { + .read_raw = ltc2309_read_raw, +}; + +static void ltc2309_regulator_disable(void *regulator) +{ + regulator_disable(regulator); +} + +static int ltc2309_probe(struct i2c_client *client) +{ + struct iio_dev *indio_dev; + struct ltc2309 *ltc2309; + int ret; + + indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*ltc2309)); + if (!indio_dev) + return -ENOMEM; + + ltc2309 = iio_priv(indio_dev); + ltc2309->dev = &indio_dev->dev; + ltc2309->client = client; + ltc2309->vref_mv = 4096; /* Default to the internal ref */ + + indio_dev->name = "ltc2309"; + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->channels = ltc2309_channels; + indio_dev->num_channels = ARRAY_SIZE(ltc2309_channels); + indio_dev->info = <c2309_info; + + ltc2309->vref = devm_regulator_get_optional(&client->dev, "vref"); + if (IS_ERR(ltc2309->vref)) { + ret = PTR_ERR(ltc2309->vref); + if (ret == -ENODEV) + ltc2309->vref = NULL; + else + return ret; + } + + if (ltc2309->vref) { + ret = regulator_enable(ltc2309->vref); + if (ret) + return dev_err_probe(ltc2309->dev, ret, + "failed to enable vref\n"); + + ret = devm_add_action_or_reset(ltc2309->dev, + ltc2309_regulator_disable, + ltc2309->vref); + if (ret) { + return dev_err_probe(ltc2309->dev, ret, + "failed to add regulator_disable action: %d\n", + ret); + } + + ret = regulator_get_voltage(ltc2309->vref); + if (ret < 0) + return ret; + + ltc2309->vref_mv = ret / 1000; + } + + mutex_init(<c2309->lock); + + return devm_iio_device_register(&client->dev, indio_dev); +} + +static const struct of_device_id ltc2309_of_match[] = { + { .compatible = "lltc,ltc2309" }, + { } +}; +MODULE_DEVICE_TABLE(of, ltc2309_of_match); + +static const struct i2c_device_id ltc2309_id[] = { + { "ltc2309" }, + { } +}; +MODULE_DEVICE_TABLE(i2c, ltc2309_id); + +static struct i2c_driver ltc2309_driver = { + .driver = { + .name = "ltc2309", + .of_match_table = ltc2309_of_match, + }, + .probe = ltc2309_probe, + .id_table = ltc2309_id, +}; +module_i2c_driver(ltc2309_driver); + +MODULE_AUTHOR("Liam Beguin <liambeguin@gmail.com>"); +MODULE_DESCRIPTION("Linear Technology LTC2309 ADC"); +MODULE_LICENSE("GPL v2"); |