// 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");