1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * AD7303 Digital to analog converters driver
4 *
5 * Copyright 2013 Analog Devices Inc.
6 */
7
8 #include <linux/err.h>
9 #include <linux/module.h>
10 #include <linux/mod_devicetable.h>
11 #include <linux/kernel.h>
12 #include <linux/spi/spi.h>
13 #include <linux/slab.h>
14 #include <linux/sysfs.h>
15 #include <linux/regulator/consumer.h>
16
17 #include <linux/iio/iio.h>
18 #include <linux/iio/sysfs.h>
19
20 #define AD7303_CFG_EXTERNAL_VREF BIT(15)
21 #define AD7303_CFG_POWER_DOWN(ch) BIT(11 + (ch))
22 #define AD7303_CFG_ADDR_OFFSET 10
23
24 #define AD7303_CMD_UPDATE_DAC (0x3 << 8)
25
26 /**
27 * struct ad7303_state - driver instance specific data
28 * @spi: the device for this driver instance
29 * @config: cached config register value
30 * @dac_cache: current DAC raw value (chip does not support readback)
31 * @vdd_reg: reference to VDD regulator
32 * @vref_reg: reference to VREF regulator
33 * @lock: protect writes and cache updates
34 * @data: spi transfer buffer
35 */
36
37 struct ad7303_state {
38 struct spi_device *spi;
39 uint16_t config;
40 uint8_t dac_cache[2];
41
42 struct regulator *vdd_reg;
43 struct regulator *vref_reg;
44
45 struct mutex lock;
46 /*
47 * DMA (thus cache coherency maintenance) may require the
48 * transfer buffers to live in their own cache lines.
49 */
50 __be16 data __aligned(IIO_DMA_MINALIGN);
51 };
52
ad7303_write(struct ad7303_state * st,unsigned int chan,uint8_t val)53 static int ad7303_write(struct ad7303_state *st, unsigned int chan,
54 uint8_t val)
55 {
56 st->data = cpu_to_be16(AD7303_CMD_UPDATE_DAC |
57 (chan << AD7303_CFG_ADDR_OFFSET) |
58 st->config | val);
59
60 return spi_write(st->spi, &st->data, sizeof(st->data));
61 }
62
ad7303_read_dac_powerdown(struct iio_dev * indio_dev,uintptr_t private,const struct iio_chan_spec * chan,char * buf)63 static ssize_t ad7303_read_dac_powerdown(struct iio_dev *indio_dev,
64 uintptr_t private, const struct iio_chan_spec *chan, char *buf)
65 {
66 struct ad7303_state *st = iio_priv(indio_dev);
67
68 return sysfs_emit(buf, "%d\n", (bool)(st->config &
69 AD7303_CFG_POWER_DOWN(chan->channel)));
70 }
71
ad7303_write_dac_powerdown(struct iio_dev * indio_dev,uintptr_t private,const struct iio_chan_spec * chan,const char * buf,size_t len)72 static ssize_t ad7303_write_dac_powerdown(struct iio_dev *indio_dev,
73 uintptr_t private, const struct iio_chan_spec *chan, const char *buf,
74 size_t len)
75 {
76 struct ad7303_state *st = iio_priv(indio_dev);
77 bool pwr_down;
78 int ret;
79
80 ret = kstrtobool(buf, &pwr_down);
81 if (ret)
82 return ret;
83
84 mutex_lock(&st->lock);
85
86 if (pwr_down)
87 st->config |= AD7303_CFG_POWER_DOWN(chan->channel);
88 else
89 st->config &= ~AD7303_CFG_POWER_DOWN(chan->channel);
90
91 /* There is no noop cmd which allows us to only update the powerdown
92 * mode, so just write one of the DAC channels again */
93 ad7303_write(st, chan->channel, st->dac_cache[chan->channel]);
94
95 mutex_unlock(&st->lock);
96 return len;
97 }
98
ad7303_get_vref(struct ad7303_state * st,struct iio_chan_spec const * chan)99 static int ad7303_get_vref(struct ad7303_state *st,
100 struct iio_chan_spec const *chan)
101 {
102 int ret;
103
104 if (st->config & AD7303_CFG_EXTERNAL_VREF)
105 return regulator_get_voltage(st->vref_reg);
106
107 ret = regulator_get_voltage(st->vdd_reg);
108 if (ret < 0)
109 return ret;
110 return ret / 2;
111 }
112
ad7303_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long info)113 static int ad7303_read_raw(struct iio_dev *indio_dev,
114 struct iio_chan_spec const *chan, int *val, int *val2, long info)
115 {
116 struct ad7303_state *st = iio_priv(indio_dev);
117 int vref_uv;
118
119 switch (info) {
120 case IIO_CHAN_INFO_RAW:
121 mutex_lock(&st->lock);
122 *val = st->dac_cache[chan->channel];
123 mutex_unlock(&st->lock);
124 return IIO_VAL_INT;
125 case IIO_CHAN_INFO_SCALE:
126 vref_uv = ad7303_get_vref(st, chan);
127 if (vref_uv < 0)
128 return vref_uv;
129
130 *val = 2 * vref_uv / 1000;
131 *val2 = chan->scan_type.realbits;
132
133 return IIO_VAL_FRACTIONAL_LOG2;
134 default:
135 break;
136 }
137 return -EINVAL;
138 }
139
ad7303_write_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int val,int val2,long mask)140 static int ad7303_write_raw(struct iio_dev *indio_dev,
141 struct iio_chan_spec const *chan, int val, int val2, long mask)
142 {
143 struct ad7303_state *st = iio_priv(indio_dev);
144 int ret;
145
146 switch (mask) {
147 case IIO_CHAN_INFO_RAW:
148 if (val >= (1 << chan->scan_type.realbits) || val < 0)
149 return -EINVAL;
150
151 mutex_lock(&st->lock);
152 ret = ad7303_write(st, chan->address, val);
153 if (ret == 0)
154 st->dac_cache[chan->channel] = val;
155 mutex_unlock(&st->lock);
156 break;
157 default:
158 ret = -EINVAL;
159 }
160
161 return ret;
162 }
163
164 static const struct iio_info ad7303_info = {
165 .read_raw = ad7303_read_raw,
166 .write_raw = ad7303_write_raw,
167 };
168
169 static const struct iio_chan_spec_ext_info ad7303_ext_info[] = {
170 {
171 .name = "powerdown",
172 .read = ad7303_read_dac_powerdown,
173 .write = ad7303_write_dac_powerdown,
174 .shared = IIO_SEPARATE,
175 },
176 { },
177 };
178
179 #define AD7303_CHANNEL(chan) { \
180 .type = IIO_VOLTAGE, \
181 .indexed = 1, \
182 .output = 1, \
183 .channel = (chan), \
184 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
185 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
186 .address = (chan), \
187 .scan_type = { \
188 .sign = 'u', \
189 .realbits = 8, \
190 .storagebits = 8, \
191 .shift = 0, \
192 }, \
193 .ext_info = ad7303_ext_info, \
194 }
195
196 static const struct iio_chan_spec ad7303_channels[] = {
197 AD7303_CHANNEL(0),
198 AD7303_CHANNEL(1),
199 };
200
ad7303_reg_disable(void * reg)201 static void ad7303_reg_disable(void *reg)
202 {
203 regulator_disable(reg);
204 }
205
ad7303_probe(struct spi_device * spi)206 static int ad7303_probe(struct spi_device *spi)
207 {
208 const struct spi_device_id *id = spi_get_device_id(spi);
209 struct iio_dev *indio_dev;
210 struct ad7303_state *st;
211 int ret;
212
213 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
214 if (indio_dev == NULL)
215 return -ENOMEM;
216
217 st = iio_priv(indio_dev);
218
219 st->spi = spi;
220
221 mutex_init(&st->lock);
222
223 st->vdd_reg = devm_regulator_get(&spi->dev, "Vdd");
224 if (IS_ERR(st->vdd_reg))
225 return PTR_ERR(st->vdd_reg);
226
227 ret = regulator_enable(st->vdd_reg);
228 if (ret)
229 return ret;
230
231 ret = devm_add_action_or_reset(&spi->dev, ad7303_reg_disable, st->vdd_reg);
232 if (ret)
233 return ret;
234
235 st->vref_reg = devm_regulator_get_optional(&spi->dev, "REF");
236 if (IS_ERR(st->vref_reg)) {
237 ret = PTR_ERR(st->vref_reg);
238 if (ret != -ENODEV)
239 return ret;
240 st->vref_reg = NULL;
241 }
242
243 if (st->vref_reg) {
244 ret = regulator_enable(st->vref_reg);
245 if (ret)
246 return ret;
247
248 ret = devm_add_action_or_reset(&spi->dev, ad7303_reg_disable,
249 st->vref_reg);
250 if (ret)
251 return ret;
252
253 st->config |= AD7303_CFG_EXTERNAL_VREF;
254 }
255
256 indio_dev->name = id->name;
257 indio_dev->info = &ad7303_info;
258 indio_dev->modes = INDIO_DIRECT_MODE;
259 indio_dev->channels = ad7303_channels;
260 indio_dev->num_channels = ARRAY_SIZE(ad7303_channels);
261
262 return devm_iio_device_register(&spi->dev, indio_dev);
263 }
264
265 static const struct of_device_id ad7303_spi_of_match[] = {
266 { .compatible = "adi,ad7303", },
267 { /* sentinel */ },
268 };
269 MODULE_DEVICE_TABLE(of, ad7303_spi_of_match);
270
271 static const struct spi_device_id ad7303_spi_ids[] = {
272 { "ad7303", 0 },
273 {}
274 };
275 MODULE_DEVICE_TABLE(spi, ad7303_spi_ids);
276
277 static struct spi_driver ad7303_driver = {
278 .driver = {
279 .name = "ad7303",
280 .of_match_table = ad7303_spi_of_match,
281 },
282 .probe = ad7303_probe,
283 .id_table = ad7303_spi_ids,
284 };
285 module_spi_driver(ad7303_driver);
286
287 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
288 MODULE_DESCRIPTION("Analog Devices AD7303 DAC driver");
289 MODULE_LICENSE("GPL v2");
290