1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Analog Devices AD5110 digital potentiometer driver
4 *
5 * Copyright (C) 2021 Mugilraj Dhavachelvan <dmugil2000@gmail.com>
6 *
7 * Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/AD5110_5112_5114.pdf
8 */
9
10 #include <linux/bitfield.h>
11 #include <linux/delay.h>
12 #include <linux/device.h>
13 #include <linux/i2c.h>
14 #include <linux/module.h>
15
16 #include <linux/iio/iio.h>
17 #include <linux/iio/sysfs.h>
18
19 /* AD5110 commands */
20 #define AD5110_EEPROM_WR 1
21 #define AD5110_RDAC_WR 2
22 #define AD5110_SHUTDOWN 3
23 #define AD5110_RESET 4
24 #define AD5110_RDAC_RD 5
25 #define AD5110_EEPROM_RD 6
26
27 /* AD5110_EEPROM_RD data */
28 #define AD5110_WIPER_POS 0
29 #define AD5110_RESISTOR_TOL 1
30
31 #define AD5110_WIPER_RESISTANCE 70
32
33 struct ad5110_cfg {
34 int max_pos;
35 int kohms;
36 int shift;
37 };
38
39 enum ad5110_type {
40 AD5110_10,
41 AD5110_80,
42 AD5112_05,
43 AD5112_10,
44 AD5112_80,
45 AD5114_10,
46 AD5114_80,
47 };
48
49 static const struct ad5110_cfg ad5110_cfg[] = {
50 [AD5110_10] = { .max_pos = 128, .kohms = 10 },
51 [AD5110_80] = { .max_pos = 128, .kohms = 80 },
52 [AD5112_05] = { .max_pos = 64, .kohms = 5, .shift = 1 },
53 [AD5112_10] = { .max_pos = 64, .kohms = 10, .shift = 1 },
54 [AD5112_80] = { .max_pos = 64, .kohms = 80, .shift = 1 },
55 [AD5114_10] = { .max_pos = 32, .kohms = 10, .shift = 2 },
56 [AD5114_80] = { .max_pos = 32, .kohms = 80, .shift = 2 },
57 };
58
59 struct ad5110_data {
60 struct i2c_client *client;
61 s16 tol; /* resistor tolerance */
62 bool enable;
63 struct mutex lock;
64 const struct ad5110_cfg *cfg;
65 /*
66 * DMA (thus cache coherency maintenance) may require the
67 * transfer buffers to live in their own cache lines.
68 */
69 u8 buf[2] __aligned(IIO_DMA_MINALIGN);
70 };
71
72 static const struct iio_chan_spec ad5110_channels[] = {
73 {
74 .type = IIO_RESISTANCE,
75 .output = 1,
76 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_OFFSET) |
77 BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_ENABLE),
78 },
79 };
80
ad5110_read(struct ad5110_data * data,u8 cmd,int * val)81 static int ad5110_read(struct ad5110_data *data, u8 cmd, int *val)
82 {
83 int ret;
84
85 mutex_lock(&data->lock);
86 data->buf[0] = cmd;
87 data->buf[1] = *val;
88
89 ret = i2c_master_send_dmasafe(data->client, data->buf, sizeof(data->buf));
90 if (ret < 0) {
91 goto error;
92 } else if (ret != sizeof(data->buf)) {
93 ret = -EIO;
94 goto error;
95 }
96
97 ret = i2c_master_recv_dmasafe(data->client, data->buf, 1);
98 if (ret < 0) {
99 goto error;
100 } else if (ret != 1) {
101 ret = -EIO;
102 goto error;
103 }
104
105 *val = data->buf[0];
106 ret = 0;
107
108 error:
109 mutex_unlock(&data->lock);
110 return ret;
111 }
112
ad5110_write(struct ad5110_data * data,u8 cmd,u8 val)113 static int ad5110_write(struct ad5110_data *data, u8 cmd, u8 val)
114 {
115 int ret;
116
117 mutex_lock(&data->lock);
118 data->buf[0] = cmd;
119 data->buf[1] = val;
120
121 ret = i2c_master_send_dmasafe(data->client, data->buf, sizeof(data->buf));
122 if (ret < 0) {
123 goto error;
124 } else if (ret != sizeof(data->buf)) {
125 ret = -EIO;
126 goto error;
127 }
128
129 ret = 0;
130
131 error:
132 mutex_unlock(&data->lock);
133 return ret;
134 }
135
ad5110_resistor_tol(struct ad5110_data * data,u8 cmd,int val)136 static int ad5110_resistor_tol(struct ad5110_data *data, u8 cmd, int val)
137 {
138 int ret;
139
140 ret = ad5110_read(data, cmd, &val);
141 if (ret)
142 return ret;
143
144 data->tol = data->cfg->kohms * (val & GENMASK(6, 0)) * 10 / 8;
145 if (!(val & BIT(7)))
146 data->tol *= -1;
147
148 return 0;
149 }
150
store_eeprom_show(struct device * dev,struct device_attribute * attr,char * buf)151 static ssize_t store_eeprom_show(struct device *dev,
152 struct device_attribute *attr,
153 char *buf)
154 {
155 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
156 struct ad5110_data *data = iio_priv(indio_dev);
157 int val = AD5110_WIPER_POS;
158 int ret;
159
160 ret = ad5110_read(data, AD5110_EEPROM_RD, &val);
161 if (ret)
162 return ret;
163
164 val = val >> data->cfg->shift;
165 return iio_format_value(buf, IIO_VAL_INT, 1, &val);
166 }
167
store_eeprom_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t len)168 static ssize_t store_eeprom_store(struct device *dev,
169 struct device_attribute *attr,
170 const char *buf, size_t len)
171 {
172 struct iio_dev *indio_dev = dev_to_iio_dev(dev);
173 struct ad5110_data *data = iio_priv(indio_dev);
174 int ret;
175
176 ret = ad5110_write(data, AD5110_EEPROM_WR, 0);
177 if (ret) {
178 dev_err(&data->client->dev, "RDAC to EEPROM write failed\n");
179 return ret;
180 }
181
182 /* The storing of EEPROM data takes approximately 18 ms. */
183 msleep(20);
184
185 return len;
186 }
187
188 static IIO_DEVICE_ATTR_RW(store_eeprom, 0);
189
190 static struct attribute *ad5110_attributes[] = {
191 &iio_dev_attr_store_eeprom.dev_attr.attr,
192 NULL
193 };
194
195 static const struct attribute_group ad5110_attribute_group = {
196 .attrs = ad5110_attributes,
197 };
198
ad5110_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)199 static int ad5110_read_raw(struct iio_dev *indio_dev,
200 struct iio_chan_spec const *chan,
201 int *val, int *val2, long mask)
202 {
203 struct ad5110_data *data = iio_priv(indio_dev);
204 int ret;
205
206 switch (mask) {
207 case IIO_CHAN_INFO_RAW:
208 ret = ad5110_read(data, AD5110_RDAC_RD, val);
209 if (ret)
210 return ret;
211
212 *val = *val >> data->cfg->shift;
213 return IIO_VAL_INT;
214 case IIO_CHAN_INFO_OFFSET:
215 *val = AD5110_WIPER_RESISTANCE * data->cfg->max_pos;
216 *val2 = 1000 * data->cfg->kohms + data->tol;
217 return IIO_VAL_FRACTIONAL;
218 case IIO_CHAN_INFO_SCALE:
219 *val = 1000 * data->cfg->kohms + data->tol;
220 *val2 = data->cfg->max_pos;
221 return IIO_VAL_FRACTIONAL;
222 case IIO_CHAN_INFO_ENABLE:
223 *val = data->enable;
224 return IIO_VAL_INT;
225 default:
226 return -EINVAL;
227 }
228 }
229
ad5110_write_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int val,int val2,long mask)230 static int ad5110_write_raw(struct iio_dev *indio_dev,
231 struct iio_chan_spec const *chan,
232 int val, int val2, long mask)
233 {
234 struct ad5110_data *data = iio_priv(indio_dev);
235 int ret;
236
237 switch (mask) {
238 case IIO_CHAN_INFO_RAW:
239 if (val > data->cfg->max_pos || val < 0)
240 return -EINVAL;
241
242 return ad5110_write(data, AD5110_RDAC_WR, val << data->cfg->shift);
243 case IIO_CHAN_INFO_ENABLE:
244 if (val < 0 || val > 1)
245 return -EINVAL;
246 if (data->enable == val)
247 return 0;
248 ret = ad5110_write(data, AD5110_SHUTDOWN, val ? 0 : 1);
249 if (ret)
250 return ret;
251 data->enable = val;
252 return 0;
253 default:
254 return -EINVAL;
255 }
256 }
257
258 static const struct iio_info ad5110_info = {
259 .read_raw = ad5110_read_raw,
260 .write_raw = ad5110_write_raw,
261 .attrs = &ad5110_attribute_group,
262 };
263
264 #define AD5110_COMPATIBLE(of_compatible, cfg) { \
265 .compatible = of_compatible, \
266 .data = &ad5110_cfg[cfg], \
267 }
268
269 static const struct of_device_id ad5110_of_match[] = {
270 AD5110_COMPATIBLE("adi,ad5110-10", AD5110_10),
271 AD5110_COMPATIBLE("adi,ad5110-80", AD5110_80),
272 AD5110_COMPATIBLE("adi,ad5112-05", AD5112_05),
273 AD5110_COMPATIBLE("adi,ad5112-10", AD5112_10),
274 AD5110_COMPATIBLE("adi,ad5112-80", AD5112_80),
275 AD5110_COMPATIBLE("adi,ad5114-10", AD5114_10),
276 AD5110_COMPATIBLE("adi,ad5114-80", AD5114_80),
277 { }
278 };
279 MODULE_DEVICE_TABLE(of, ad5110_of_match);
280
281 #define AD5110_ID_TABLE(_name, cfg) { \
282 .name = _name, \
283 .driver_data = (kernel_ulong_t)&ad5110_cfg[cfg], \
284 }
285
286 static const struct i2c_device_id ad5110_id[] = {
287 AD5110_ID_TABLE("ad5110-10", AD5110_10),
288 AD5110_ID_TABLE("ad5110-80", AD5110_80),
289 AD5110_ID_TABLE("ad5112-05", AD5112_05),
290 AD5110_ID_TABLE("ad5112-10", AD5112_10),
291 AD5110_ID_TABLE("ad5112-80", AD5112_80),
292 AD5110_ID_TABLE("ad5114-10", AD5114_10),
293 AD5110_ID_TABLE("ad5114-80", AD5114_80),
294 { }
295 };
296 MODULE_DEVICE_TABLE(i2c, ad5110_id);
297
ad5110_probe(struct i2c_client * client)298 static int ad5110_probe(struct i2c_client *client)
299 {
300 struct device *dev = &client->dev;
301 struct iio_dev *indio_dev;
302 struct ad5110_data *data;
303 int ret;
304
305 indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
306 if (!indio_dev)
307 return -ENOMEM;
308
309 data = iio_priv(indio_dev);
310 data->client = client;
311 mutex_init(&data->lock);
312 data->enable = 1;
313 data->cfg = i2c_get_match_data(client);
314
315 /* refresh RDAC register with EEPROM */
316 ret = ad5110_write(data, AD5110_RESET, 0);
317 if (ret) {
318 dev_err(dev, "Refresh RDAC with EEPROM failed\n");
319 return ret;
320 }
321
322 ret = ad5110_resistor_tol(data, AD5110_EEPROM_RD, AD5110_RESISTOR_TOL);
323 if (ret) {
324 dev_err(dev, "Read resistor tolerance failed\n");
325 return ret;
326 }
327
328 indio_dev->modes = INDIO_DIRECT_MODE;
329 indio_dev->info = &ad5110_info;
330 indio_dev->channels = ad5110_channels;
331 indio_dev->num_channels = ARRAY_SIZE(ad5110_channels);
332 indio_dev->name = client->name;
333
334 return devm_iio_device_register(dev, indio_dev);
335 }
336
337 static struct i2c_driver ad5110_driver = {
338 .driver = {
339 .name = "ad5110",
340 .of_match_table = ad5110_of_match,
341 },
342 .probe = ad5110_probe,
343 .id_table = ad5110_id,
344 };
345 module_i2c_driver(ad5110_driver);
346
347 MODULE_AUTHOR("Mugilraj Dhavachelvan <dmugil2000@gmail.com>");
348 MODULE_DESCRIPTION("AD5110 digital potentiometer");
349 MODULE_LICENSE("GPL v2");
350