1// SPDX-License-Identifier: GPL-2.0
2/*
3 * The LTC2309 is an 8-Channel, 12-Bit SAR ADC with an I2C Interface.
4 *
5 * Datasheet:
6 * https://www.analog.com/media/en/technical-documentation/data-sheets/2309fd.pdf
7 *
8 * Copyright (c) 2023, Liam Beguin <liambeguin@gmail.com>
9 */
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>
17
18#define LTC2309_ADC_RESOLUTION 12
19
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)
27
28/**
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
35 */
36struct ltc2309 {
37 struct device *dev;
38 struct i2c_client *client;
39 struct regulator *vref;
40 struct mutex lock; /* serialize data access */
41 int vref_mv;
42};
43
44/* Order matches expected channel address, See datasheet Table 1. */
45enum ltc2309_channels {
46 LTC2309_CH0_CH1 = 0,
47 LTC2309_CH2_CH3,
48 LTC2309_CH4_CH5,
49 LTC2309_CH6_CH7,
50 LTC2309_CH1_CH0,
51 LTC2309_CH3_CH2,
52 LTC2309_CH5_CH4,
53 LTC2309_CH7_CH6,
54 LTC2309_CH0,
55 LTC2309_CH2,
56 LTC2309_CH4,
57 LTC2309_CH6,
58 LTC2309_CH1,
59 LTC2309_CH3,
60 LTC2309_CH5,
61 LTC2309_CH7,
62};
63
64#define LTC2309_CHAN(_chan, _addr) { \
65 .type = IIO_VOLTAGE, \
66 .indexed = 1, \
67 .address = _addr, \
68 .channel = _chan, \
69 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
70 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
71}
72
73#define LTC2309_DIFF_CHAN(_chan, _chan2, _addr) { \
74 .type = IIO_VOLTAGE, \
75 .differential = 1, \
76 .indexed = 1, \
77 .address = _addr, \
78 .channel = _chan, \
79 .channel2 = _chan2, \
80 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
81 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
82}
83
84static 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),
101};
102
103static int ltc2309_read_raw_channel(struct ltc2309 *ltc2309,
104 unsigned long address, int *val)
105{
106 int ret;
107 u16 buf;
108 u8 din;
109
110 din = FIELD_PREP(LTC2309_DIN_CH_MASK, address & 0x0f) |
111 FIELD_PREP(LTC2309_DIN_UNI, 1) |
112 FIELD_PREP(LTC2309_DIN_SLEEP, 0);
113
114 ret = i2c_smbus_write_byte(client: ltc2309->client, value: din);
115 if (ret < 0) {
116 dev_err(ltc2309->dev, "i2c command failed: %pe\n",
117 ERR_PTR(ret));
118 return ret;
119 }
120
121 ret = i2c_master_recv(client: ltc2309->client, buf: (char *)&buf, count: 2);
122 if (ret < 0) {
123 dev_err(ltc2309->dev, "i2c read failed: %pe\n", ERR_PTR(ret));
124 return ret;
125 }
126
127 *val = be16_to_cpu(buf) >> 4;
128
129 return ret;
130}
131
132static int ltc2309_read_raw(struct iio_dev *indio_dev,
133 struct iio_chan_spec const *chan, int *val,
134 int *val2, long mask)
135{
136 struct ltc2309 *ltc2309 = iio_priv(indio_dev);
137 int ret;
138
139 switch (mask) {
140 case IIO_CHAN_INFO_RAW:
141 mutex_lock(&ltc2309->lock);
142 ret = ltc2309_read_raw_channel(ltc2309, address: chan->address, val);
143 mutex_unlock(lock: &ltc2309->lock);
144 if (ret < 0)
145 return -EINVAL;
146 return IIO_VAL_INT;
147 case IIO_CHAN_INFO_SCALE:
148 *val = ltc2309->vref_mv;
149 *val2 = LTC2309_ADC_RESOLUTION;
150 return IIO_VAL_FRACTIONAL_LOG2;
151 default:
152 return -EINVAL;
153 }
154}
155
156static const struct iio_info ltc2309_info = {
157 .read_raw = ltc2309_read_raw,
158};
159
160static void ltc2309_regulator_disable(void *regulator)
161{
162 regulator_disable(regulator);
163}
164
165static int ltc2309_probe(struct i2c_client *client)
166{
167 struct iio_dev *indio_dev;
168 struct ltc2309 *ltc2309;
169 int ret;
170
171 indio_dev = devm_iio_device_alloc(parent: &client->dev, sizeof_priv: sizeof(*ltc2309));
172 if (!indio_dev)
173 return -ENOMEM;
174
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 */
179
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 = &ltc2309_info;
185
186 ltc2309->vref = devm_regulator_get_optional(dev: &client->dev, id: "vref");
187 if (IS_ERR(ptr: ltc2309->vref)) {
188 ret = PTR_ERR(ptr: ltc2309->vref);
189 if (ret == -ENODEV)
190 ltc2309->vref = NULL;
191 else
192 return ret;
193 }
194
195 if (ltc2309->vref) {
196 ret = regulator_enable(regulator: ltc2309->vref);
197 if (ret)
198 return dev_err_probe(dev: ltc2309->dev, err: ret,
199 fmt: "failed to enable vref\n");
200
201 ret = devm_add_action_or_reset(ltc2309->dev,
202 ltc2309_regulator_disable,
203 ltc2309->vref);
204 if (ret) {
205 return dev_err_probe(dev: ltc2309->dev, err: ret,
206 fmt: "failed to add regulator_disable action: %d\n",
207 ret);
208 }
209
210 ret = regulator_get_voltage(regulator: ltc2309->vref);
211 if (ret < 0)
212 return ret;
213
214 ltc2309->vref_mv = ret / 1000;
215 }
216
217 mutex_init(&ltc2309->lock);
218
219 return devm_iio_device_register(&client->dev, indio_dev);
220}
221
222static const struct of_device_id ltc2309_of_match[] = {
223 { .compatible = "lltc,ltc2309" },
224 { }
225};
226MODULE_DEVICE_TABLE(of, ltc2309_of_match);
227
228static const struct i2c_device_id ltc2309_id[] = {
229 { "ltc2309" },
230 { }
231};
232MODULE_DEVICE_TABLE(i2c, ltc2309_id);
233
234static struct i2c_driver ltc2309_driver = {
235 .driver = {
236 .name = "ltc2309",
237 .of_match_table = ltc2309_of_match,
238 },
239 .probe = ltc2309_probe,
240 .id_table = ltc2309_id,
241};
242module_i2c_driver(ltc2309_driver);
243
244MODULE_AUTHOR("Liam Beguin <liambeguin@gmail.com>");
245MODULE_DESCRIPTION("Linear Technology LTC2309 ADC");
246MODULE_LICENSE("GPL v2");
247

source code of linux/drivers/iio/adc/ltc2309.c