1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * The LTC2305 is a 2-Channel, 12-Bit SAR ADC with an I2C Interface.
4 * The LTC2309 is an 8-Channel, 12-Bit SAR ADC with an I2C Interface.
5 *
6 * Datasheet:
7 * https://www.analog.com/media/en/technical-documentation/data-sheets/23015fb.pdf
8 * https://www.analog.com/media/en/technical-documentation/data-sheets/2309fd.pdf
9 *
10 * Copyright (c) 2023, Liam Beguin <liambeguin@gmail.com>
11 */
12 #include <linux/bitfield.h>
13 #include <linux/i2c.h>
14 #include <linux/iio/iio.h>
15 #include <linux/kernel.h>
16 #include <linux/module.h>
17 #include <linux/mutex.h>
18 #include <linux/regulator/consumer.h>
19
20 #define LTC2309_ADC_RESOLUTION 12
21 #define LTC2309_INTERNAL_REF_MV 4096
22
23 #define LTC2309_DIN_CH_MASK GENMASK(7, 4)
24 #define LTC2309_DIN_SDN BIT(7)
25 #define LTC2309_DIN_OSN BIT(6)
26 #define LTC2309_DIN_S1 BIT(5)
27 #define LTC2309_DIN_S0 BIT(4)
28 #define LTC2309_DIN_UNI BIT(3)
29 #define LTC2309_DIN_SLEEP BIT(2)
30
31 /**
32 * struct ltc2309 - internal device data structure
33 * @dev: Device reference
34 * @client: I2C reference
35 * @lock: Lock to serialize data access
36 * @vref_mv: Internal voltage reference
37 */
38 struct ltc2309 {
39 struct device *dev;
40 struct i2c_client *client;
41 struct mutex lock; /* serialize data access */
42 int vref_mv;
43 };
44
45 /* Order matches expected channel address, See datasheet Table 1. */
46 enum ltc2305_channels {
47 LTC2305_CH0_CH1 = 0x0,
48 LTC2305_CH1_CH0 = 0x4,
49 LTC2305_CH0 = 0x8,
50 LTC2305_CH1 = 0xc,
51 };
52
53 enum ltc2309_channels {
54 LTC2309_CH0_CH1 = 0x0,
55 LTC2309_CH2_CH3 = 0x1,
56 LTC2309_CH4_CH5 = 0x2,
57 LTC2309_CH6_CH7 = 0x3,
58 LTC2309_CH1_CH0 = 0x4,
59 LTC2309_CH3_CH2 = 0x5,
60 LTC2309_CH5_CH4 = 0x6,
61 LTC2309_CH7_CH6 = 0x7,
62 LTC2309_CH0 = 0x8,
63 LTC2309_CH2 = 0x9,
64 LTC2309_CH4 = 0xa,
65 LTC2309_CH6 = 0xb,
66 LTC2309_CH1 = 0xc,
67 LTC2309_CH3 = 0xd,
68 LTC2309_CH5 = 0xe,
69 LTC2309_CH7 = 0xf,
70 };
71
72 #define LTC2309_CHAN(_chan, _addr) { \
73 .type = IIO_VOLTAGE, \
74 .indexed = 1, \
75 .address = _addr, \
76 .channel = _chan, \
77 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
78 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
79 }
80
81 #define LTC2309_DIFF_CHAN(_chan, _chan2, _addr) { \
82 .type = IIO_VOLTAGE, \
83 .differential = 1, \
84 .indexed = 1, \
85 .address = _addr, \
86 .channel = _chan, \
87 .channel2 = _chan2, \
88 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
89 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
90 }
91
92 static const struct iio_chan_spec ltc2305_channels[] = {
93 LTC2309_CHAN(0, LTC2305_CH0),
94 LTC2309_CHAN(1, LTC2305_CH1),
95 LTC2309_DIFF_CHAN(0, 1, LTC2305_CH0_CH1),
96 LTC2309_DIFF_CHAN(1, 0, LTC2305_CH1_CH0),
97 };
98
99 static const struct iio_chan_spec ltc2309_channels[] = {
100 LTC2309_CHAN(0, LTC2309_CH0),
101 LTC2309_CHAN(1, LTC2309_CH1),
102 LTC2309_CHAN(2, LTC2309_CH2),
103 LTC2309_CHAN(3, LTC2309_CH3),
104 LTC2309_CHAN(4, LTC2309_CH4),
105 LTC2309_CHAN(5, LTC2309_CH5),
106 LTC2309_CHAN(6, LTC2309_CH6),
107 LTC2309_CHAN(7, LTC2309_CH7),
108 LTC2309_DIFF_CHAN(0, 1, LTC2309_CH0_CH1),
109 LTC2309_DIFF_CHAN(2, 3, LTC2309_CH2_CH3),
110 LTC2309_DIFF_CHAN(4, 5, LTC2309_CH4_CH5),
111 LTC2309_DIFF_CHAN(6, 7, LTC2309_CH6_CH7),
112 LTC2309_DIFF_CHAN(1, 0, LTC2309_CH1_CH0),
113 LTC2309_DIFF_CHAN(3, 2, LTC2309_CH3_CH2),
114 LTC2309_DIFF_CHAN(5, 4, LTC2309_CH5_CH4),
115 LTC2309_DIFF_CHAN(7, 6, LTC2309_CH7_CH6),
116 };
117
118 struct ltc2309_chip_info {
119 const char *name;
120 const struct iio_chan_spec *channels;
121 int num_channels;
122 };
123
124 static const struct ltc2309_chip_info ltc2305_chip_info = {
125 .name = "ltc2305",
126 .channels = ltc2305_channels,
127 .num_channels = ARRAY_SIZE(ltc2305_channels),
128 };
129
130 static const struct ltc2309_chip_info ltc2309_chip_info = {
131 .name = "ltc2309",
132 .channels = ltc2309_channels,
133 .num_channels = ARRAY_SIZE(ltc2309_channels),
134 };
135
ltc2309_read_raw_channel(struct ltc2309 * ltc2309,unsigned long address,int * val)136 static int ltc2309_read_raw_channel(struct ltc2309 *ltc2309,
137 unsigned long address, int *val)
138 {
139 int ret;
140 __be16 buf;
141 u8 din;
142
143 din = FIELD_PREP(LTC2309_DIN_CH_MASK, address & 0x0f) |
144 FIELD_PREP(LTC2309_DIN_UNI, 1) |
145 FIELD_PREP(LTC2309_DIN_SLEEP, 0);
146
147 ret = i2c_smbus_write_byte(ltc2309->client, din);
148 if (ret < 0) {
149 dev_err(ltc2309->dev, "i2c command failed: %pe\n",
150 ERR_PTR(ret));
151 return ret;
152 }
153
154 ret = i2c_master_recv(ltc2309->client, (char *)&buf, 2);
155 if (ret < 0) {
156 dev_err(ltc2309->dev, "i2c read failed: %pe\n", ERR_PTR(ret));
157 return ret;
158 }
159
160 *val = be16_to_cpu(buf) >> 4;
161
162 return ret;
163 }
164
ltc2309_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)165 static int ltc2309_read_raw(struct iio_dev *indio_dev,
166 struct iio_chan_spec const *chan, int *val,
167 int *val2, long mask)
168 {
169 struct ltc2309 *ltc2309 = iio_priv(indio_dev);
170 int ret;
171
172 switch (mask) {
173 case IIO_CHAN_INFO_RAW:
174 mutex_lock(<c2309->lock);
175 ret = ltc2309_read_raw_channel(ltc2309, chan->address, val);
176 mutex_unlock(<c2309->lock);
177 if (ret < 0)
178 return -EINVAL;
179 return IIO_VAL_INT;
180 case IIO_CHAN_INFO_SCALE:
181 *val = ltc2309->vref_mv;
182 *val2 = LTC2309_ADC_RESOLUTION;
183 return IIO_VAL_FRACTIONAL_LOG2;
184 default:
185 return -EINVAL;
186 }
187 }
188
189 static const struct iio_info ltc2309_info = {
190 .read_raw = ltc2309_read_raw,
191 };
192
ltc2309_probe(struct i2c_client * client)193 static int ltc2309_probe(struct i2c_client *client)
194 {
195 const struct ltc2309_chip_info *chip_info;
196 struct iio_dev *indio_dev;
197 struct ltc2309 *ltc2309;
198 int ret;
199
200 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*ltc2309));
201 if (!indio_dev)
202 return -ENOMEM;
203
204 ltc2309 = iio_priv(indio_dev);
205 chip_info = i2c_get_match_data(client);
206
207 ltc2309->dev = &indio_dev->dev;
208 ltc2309->client = client;
209
210 indio_dev->name = chip_info->name;
211 indio_dev->modes = INDIO_DIRECT_MODE;
212 indio_dev->channels = chip_info->channels;
213 indio_dev->num_channels = chip_info->num_channels;
214 indio_dev->info = <c2309_info;
215
216 ret = devm_regulator_get_enable_read_voltage(&client->dev, "vref");
217 if (ret < 0 && ret != -ENODEV)
218 return dev_err_probe(ltc2309->dev, ret,
219 "failed to get vref voltage\n");
220
221 ltc2309->vref_mv = ret == -ENODEV ? LTC2309_INTERNAL_REF_MV : ret / 1000;
222
223 mutex_init(<c2309->lock);
224
225 return devm_iio_device_register(&client->dev, indio_dev);
226 }
227
228 static const struct of_device_id ltc2309_of_match[] = {
229 { .compatible = "lltc,ltc2305", .data = <c2305_chip_info },
230 { .compatible = "lltc,ltc2309", .data = <c2309_chip_info },
231 { }
232 };
233 MODULE_DEVICE_TABLE(of, ltc2309_of_match);
234
235 static const struct i2c_device_id ltc2309_id[] = {
236 { "ltc2305", (kernel_ulong_t)<c2305_chip_info },
237 { "ltc2309", (kernel_ulong_t)<c2309_chip_info },
238 { }
239 };
240 MODULE_DEVICE_TABLE(i2c, ltc2309_id);
241
242 static struct i2c_driver ltc2309_driver = {
243 .driver = {
244 .name = "ltc2309",
245 .of_match_table = ltc2309_of_match,
246 },
247 .probe = ltc2309_probe,
248 .id_table = ltc2309_id,
249 };
250 module_i2c_driver(ltc2309_driver);
251
252 MODULE_AUTHOR("Liam Beguin <liambeguin@gmail.com>");
253 MODULE_DESCRIPTION("Linear Technology LTC2309 ADC");
254 MODULE_LICENSE("GPL v2");
255