1 // SPDX-License-Identifier: GPL-2.0
3 * The LTC2309 is an 8-Channel, 12-Bit SAR ADC with an I2C Interface.
6 * https://www.analog.com/media/en/technical-documentation/data-sheets/2309fd.pdf
8 * Copyright (c) 2023, Liam Beguin <liambeguin@gmail.com>
10 #include <linux/bitfield.h>
11 #include <linux/i2c.h>
12 #include <linux/iio/iio.h>
13 #include <linux/kernel.h>
14 #include <linux/module.h>
15 #include <linux/mutex.h>
16 #include <linux/regulator/consumer.h>
18 #define LTC2309_ADC_RESOLUTION 12
20 #define LTC2309_DIN_CH_MASK GENMASK(7, 4)
21 #define LTC2309_DIN_SDN BIT(7)
22 #define LTC2309_DIN_OSN BIT(6)
23 #define LTC2309_DIN_S1 BIT(5)
24 #define LTC2309_DIN_S0 BIT(4)
25 #define LTC2309_DIN_UNI BIT(3)
26 #define LTC2309_DIN_SLEEP BIT(2)
29 * struct ltc2309 - internal device data structure
30 * @dev: Device reference
31 * @client: I2C reference
32 * @vref: External reference source
33 * @lock: Lock to serialize data access
34 * @vref_mv: Internal voltage reference
38 struct i2c_client *client;
39 struct regulator *vref;
40 struct mutex lock; /* serialize data access */
44 /* Order matches expected channel address, See datasheet Table 1. */
45 enum ltc2309_channels {
64 #define LTC2309_CHAN(_chan, _addr) { \
65 .type = IIO_VOLTAGE, \
69 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
70 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
73 #define LTC2309_DIFF_CHAN(_chan, _chan2, _addr) { \
74 .type = IIO_VOLTAGE, \
80 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
81 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
84 static const struct iio_chan_spec ltc2309_channels[] = {
85 LTC2309_CHAN(0, LTC2309_CH0),
86 LTC2309_CHAN(1, LTC2309_CH1),
87 LTC2309_CHAN(2, LTC2309_CH2),
88 LTC2309_CHAN(3, LTC2309_CH3),
89 LTC2309_CHAN(4, LTC2309_CH4),
90 LTC2309_CHAN(5, LTC2309_CH5),
91 LTC2309_CHAN(6, LTC2309_CH6),
92 LTC2309_CHAN(7, LTC2309_CH7),
93 LTC2309_DIFF_CHAN(0, 1, LTC2309_CH0_CH1),
94 LTC2309_DIFF_CHAN(2, 3, LTC2309_CH2_CH3),
95 LTC2309_DIFF_CHAN(4, 5, LTC2309_CH4_CH5),
96 LTC2309_DIFF_CHAN(6, 7, LTC2309_CH6_CH7),
97 LTC2309_DIFF_CHAN(1, 0, LTC2309_CH1_CH0),
98 LTC2309_DIFF_CHAN(3, 2, LTC2309_CH3_CH2),
99 LTC2309_DIFF_CHAN(5, 4, LTC2309_CH5_CH4),
100 LTC2309_DIFF_CHAN(7, 6, LTC2309_CH7_CH6),
103 static int ltc2309_read_raw_channel(struct ltc2309 *ltc2309,
104 unsigned long address, int *val)
110 din = FIELD_PREP(LTC2309_DIN_CH_MASK, address & 0x0f) |
111 FIELD_PREP(LTC2309_DIN_UNI, 1) |
112 FIELD_PREP(LTC2309_DIN_SLEEP, 0);
114 ret = i2c_smbus_write_byte(ltc2309->client, din);
116 dev_err(ltc2309->dev, "i2c command failed: %pe\n",
121 ret = i2c_master_recv(ltc2309->client, (char *)&buf, 2);
123 dev_err(ltc2309->dev, "i2c read failed: %pe\n", ERR_PTR(ret));
127 *val = be16_to_cpu(buf) >> 4;
132 static int ltc2309_read_raw(struct iio_dev *indio_dev,
133 struct iio_chan_spec const *chan, int *val,
134 int *val2, long mask)
136 struct ltc2309 *ltc2309 = iio_priv(indio_dev);
140 case IIO_CHAN_INFO_RAW:
141 mutex_lock(<c2309->lock);
142 ret = ltc2309_read_raw_channel(ltc2309, chan->address, val);
143 mutex_unlock(<c2309->lock);
147 case IIO_CHAN_INFO_SCALE:
148 *val = ltc2309->vref_mv;
149 *val2 = LTC2309_ADC_RESOLUTION;
150 return IIO_VAL_FRACTIONAL_LOG2;
156 static const struct iio_info ltc2309_info = {
157 .read_raw = ltc2309_read_raw,
160 static void ltc2309_regulator_disable(void *regulator)
162 regulator_disable(regulator);
165 static int ltc2309_probe(struct i2c_client *client)
167 struct iio_dev *indio_dev;
168 struct ltc2309 *ltc2309;
171 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*ltc2309));
175 ltc2309 = iio_priv(indio_dev);
176 ltc2309->dev = &indio_dev->dev;
177 ltc2309->client = client;
178 ltc2309->vref_mv = 4096; /* Default to the internal ref */
180 indio_dev->name = "ltc2309";
181 indio_dev->modes = INDIO_DIRECT_MODE;
182 indio_dev->channels = ltc2309_channels;
183 indio_dev->num_channels = ARRAY_SIZE(ltc2309_channels);
184 indio_dev->info = <c2309_info;
186 ltc2309->vref = devm_regulator_get_optional(&client->dev, "vref");
187 if (IS_ERR(ltc2309->vref)) {
188 ret = PTR_ERR(ltc2309->vref);
190 ltc2309->vref = NULL;
196 ret = regulator_enable(ltc2309->vref);
198 return dev_err_probe(ltc2309->dev, ret,
199 "failed to enable vref\n");
201 ret = devm_add_action_or_reset(ltc2309->dev,
202 ltc2309_regulator_disable,
205 return dev_err_probe(ltc2309->dev, ret,
206 "failed to add regulator_disable action: %d\n",
210 ret = regulator_get_voltage(ltc2309->vref);
214 ltc2309->vref_mv = ret / 1000;
217 mutex_init(<c2309->lock);
219 return devm_iio_device_register(&client->dev, indio_dev);
222 static const struct of_device_id ltc2309_of_match[] = {
223 { .compatible = "lltc,ltc2309" },
226 MODULE_DEVICE_TABLE(of, ltc2309_of_match);
228 static const struct i2c_device_id ltc2309_id[] = {
232 MODULE_DEVICE_TABLE(i2c, ltc2309_id);
234 static struct i2c_driver ltc2309_driver = {
237 .of_match_table = ltc2309_of_match,
239 .probe = ltc2309_probe,
240 .id_table = ltc2309_id,
242 module_i2c_driver(ltc2309_driver);
244 MODULE_AUTHOR("Liam Beguin <liambeguin@gmail.com>");
245 MODULE_DESCRIPTION("Linear Technology LTC2309 ADC");
246 MODULE_LICENSE("GPL v2");