xref: /linux/drivers/iio/potentiometer/ds1803.c (revision 0d5ec7919f3747193f051036b2301734a4b5e1d6)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Maxim Integrated DS1803 and similar digital potentiometer driver
4  * Copyright (c) 2016 Slawomir Stepien
5  * Copyright (c) 2022 Jagath Jog J
6  *
7  * Datasheet: https://datasheets.maximintegrated.com/en/ds/DS1803.pdf
8  * Datasheet: https://datasheets.maximintegrated.com/en/ds/DS3502.pdf
9  *
10  * DEVID	#Wipers	#Positions	Resistor Opts (kOhm)	i2c address
11  * ds1803	2	256		10, 50, 100		0101xxx
12  * ds3502	1	128		10			01010xx
13  */
14 
15 #include <linux/err.h>
16 #include <linux/i2c.h>
17 #include <linux/iio/iio.h>
18 #include <linux/module.h>
19 #include <linux/mod_devicetable.h>
20 #include <linux/property.h>
21 
22 #define DS1803_WIPER_0         0xA9
23 #define DS1803_WIPER_1         0xAA
24 #define DS3502_WR_IVR          0x00
25 
26 enum ds1803_type {
27 	DS1803_010,
28 	DS1803_050,
29 	DS1803_100,
30 	DS3502,
31 };
32 
33 struct ds1803_cfg {
34 	int wipers;
35 	int avail[3];
36 	int kohms;
37 	const struct iio_chan_spec *channels;
38 	u8 num_channels;
39 	int (*read)(struct iio_dev *indio_dev,
40 		    struct iio_chan_spec const *chan, int *val);
41 };
42 
43 struct ds1803_data {
44 	struct i2c_client *client;
45 	const struct ds1803_cfg *cfg;
46 };
47 
48 #define DS1803_CHANNEL(ch, addr) {					\
49 	.type = IIO_RESISTANCE,						\
50 	.indexed = 1,							\
51 	.output = 1,							\
52 	.channel = (ch),						\
53 	.address = (addr),						\
54 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),			\
55 	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),		\
56 	.info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_RAW),   \
57 }
58 
59 static const struct iio_chan_spec ds1803_channels[] = {
60 	DS1803_CHANNEL(0, DS1803_WIPER_0),
61 	DS1803_CHANNEL(1, DS1803_WIPER_1),
62 };
63 
64 static const struct iio_chan_spec ds3502_channels[] = {
65 	DS1803_CHANNEL(0, DS3502_WR_IVR),
66 };
67 
ds1803_read(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val)68 static int ds1803_read(struct iio_dev *indio_dev,
69 		       struct iio_chan_spec const *chan,
70 		       int *val)
71 {
72 	struct ds1803_data *data = iio_priv(indio_dev);
73 	int ret;
74 	u8 result[ARRAY_SIZE(ds1803_channels)];
75 
76 	ret = i2c_master_recv(data->client, result, indio_dev->num_channels);
77 	if (ret < 0)
78 		return ret;
79 
80 	*val = result[chan->channel];
81 	return ret;
82 }
83 
ds3502_read(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val)84 static int ds3502_read(struct iio_dev *indio_dev,
85 		       struct iio_chan_spec const *chan,
86 		       int *val)
87 {
88 	struct ds1803_data *data = iio_priv(indio_dev);
89 	int ret;
90 
91 	ret = i2c_smbus_read_byte_data(data->client, chan->address);
92 	if (ret < 0)
93 		return ret;
94 
95 	*val = ret;
96 	return ret;
97 }
98 
99 static const struct ds1803_cfg ds1803_cfg[] = {
100 	[DS1803_010] = {
101 		.wipers = 2,
102 		.avail = { 0, 1, 255 },
103 		.kohms =  10,
104 		.channels = ds1803_channels,
105 		.num_channels = ARRAY_SIZE(ds1803_channels),
106 		.read = ds1803_read,
107 	},
108 	[DS1803_050] = {
109 		.wipers = 2,
110 		.avail = { 0, 1, 255 },
111 		.kohms =  50,
112 		.channels = ds1803_channels,
113 		.num_channels = ARRAY_SIZE(ds1803_channels),
114 		.read = ds1803_read,
115 	},
116 	[DS1803_100] = {
117 		.wipers = 2,
118 		.avail = { 0, 1, 255 },
119 		.kohms = 100,
120 		.channels = ds1803_channels,
121 		.num_channels = ARRAY_SIZE(ds1803_channels),
122 		.read = ds1803_read,
123 	},
124 	[DS3502] = {
125 	  .wipers = 1,
126 	  .avail = { 0, 1, 127 },
127 	  .kohms =  10,
128 	  .channels = ds3502_channels,
129 	  .num_channels = ARRAY_SIZE(ds3502_channels),
130 	  .read = ds3502_read,
131 	},
132 };
133 
ds1803_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)134 static int ds1803_read_raw(struct iio_dev *indio_dev,
135 			   struct iio_chan_spec const *chan,
136 			   int *val, int *val2, long mask)
137 {
138 	struct ds1803_data *data = iio_priv(indio_dev);
139 	int ret;
140 
141 	switch (mask) {
142 	case IIO_CHAN_INFO_RAW:
143 		ret = data->cfg->read(indio_dev, chan, val);
144 		if (ret < 0)
145 			return ret;
146 
147 		return IIO_VAL_INT;
148 
149 	case IIO_CHAN_INFO_SCALE:
150 		*val = 1000 * data->cfg->kohms;
151 		*val2 = data->cfg->avail[2]; /* Max wiper position */
152 		return IIO_VAL_FRACTIONAL;
153 	}
154 
155 	return -EINVAL;
156 }
157 
ds1803_write_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int val,int val2,long mask)158 static int ds1803_write_raw(struct iio_dev *indio_dev,
159 			    struct iio_chan_spec const *chan,
160 			    int val, int val2, long mask)
161 {
162 	struct ds1803_data *data = iio_priv(indio_dev);
163 	u8 addr = chan->address;
164 	int max_pos = data->cfg->avail[2];
165 
166 	if (val2 != 0)
167 		return -EINVAL;
168 
169 	switch (mask) {
170 	case IIO_CHAN_INFO_RAW:
171 		if (val > max_pos || val < 0)
172 			return -EINVAL;
173 		break;
174 	default:
175 		return -EINVAL;
176 	}
177 
178 	return i2c_smbus_write_byte_data(data->client, addr, val);
179 }
180 
ds1803_read_avail(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,const int ** vals,int * type,int * length,long mask)181 static int ds1803_read_avail(struct iio_dev *indio_dev,
182 			     struct iio_chan_spec const *chan,
183 			     const int **vals, int *type,
184 			     int *length, long mask)
185 {
186 	struct ds1803_data *data = iio_priv(indio_dev);
187 
188 	switch (mask) {
189 	case IIO_CHAN_INFO_RAW:
190 		*vals = data->cfg->avail;
191 		*length = ARRAY_SIZE(data->cfg->avail);
192 		*type = IIO_VAL_INT;
193 		return IIO_AVAIL_RANGE;
194 	}
195 	return -EINVAL;
196 }
197 
198 static const struct iio_info ds1803_info = {
199 	.read_raw = ds1803_read_raw,
200 	.write_raw = ds1803_write_raw,
201 	.read_avail = ds1803_read_avail,
202 };
203 
ds1803_probe(struct i2c_client * client)204 static int ds1803_probe(struct i2c_client *client)
205 {
206 	struct device *dev = &client->dev;
207 	struct ds1803_data *data;
208 	struct iio_dev *indio_dev;
209 
210 	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
211 	if (!indio_dev)
212 		return -ENOMEM;
213 
214 	i2c_set_clientdata(client, indio_dev);
215 
216 	data = iio_priv(indio_dev);
217 	data->client = client;
218 	data->cfg = i2c_get_match_data(client);
219 
220 	indio_dev->info = &ds1803_info;
221 	indio_dev->channels = data->cfg->channels;
222 	indio_dev->num_channels = data->cfg->num_channels;
223 	indio_dev->name = client->name;
224 
225 	return devm_iio_device_register(dev, indio_dev);
226 }
227 
228 static const struct of_device_id ds1803_dt_ids[] = {
229 	{ .compatible = "maxim,ds1803-010", .data = &ds1803_cfg[DS1803_010] },
230 	{ .compatible = "maxim,ds1803-050", .data = &ds1803_cfg[DS1803_050] },
231 	{ .compatible = "maxim,ds1803-100", .data = &ds1803_cfg[DS1803_100] },
232 	{ .compatible = "maxim,ds3502", .data = &ds1803_cfg[DS3502] },
233 	{ }
234 };
235 MODULE_DEVICE_TABLE(of, ds1803_dt_ids);
236 
237 static const struct i2c_device_id ds1803_id[] = {
238 	{ "ds1803-010", (kernel_ulong_t)&ds1803_cfg[DS1803_010] },
239 	{ "ds1803-050", (kernel_ulong_t)&ds1803_cfg[DS1803_050] },
240 	{ "ds1803-100", (kernel_ulong_t)&ds1803_cfg[DS1803_100] },
241 	{ "ds3502", (kernel_ulong_t)&ds1803_cfg[DS3502] },
242 	{ }
243 };
244 MODULE_DEVICE_TABLE(i2c, ds1803_id);
245 
246 static struct i2c_driver ds1803_driver = {
247 	.driver = {
248 		.name	= "ds1803",
249 		.of_match_table = ds1803_dt_ids,
250 	},
251 	.probe		= ds1803_probe,
252 	.id_table	= ds1803_id,
253 };
254 
255 module_i2c_driver(ds1803_driver);
256 
257 MODULE_AUTHOR("Slawomir Stepien <sst@poczta.fm>");
258 MODULE_AUTHOR("Jagath Jog J <jagathjog1996@gmail.com>");
259 MODULE_DESCRIPTION("DS1803 digital potentiometer");
260 MODULE_LICENSE("GPL v2");
261