xref: /openbmc/linux/drivers/iio/dac/ad7303.c (revision abe9af53)
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 #include <linux/platform_data/ad7303.h>
21 
22 #define AD7303_CFG_EXTERNAL_VREF BIT(15)
23 #define AD7303_CFG_POWER_DOWN(ch) BIT(11 + (ch))
24 #define AD7303_CFG_ADDR_OFFSET	10
25 
26 #define AD7303_CMD_UPDATE_DAC	(0x3 << 8)
27 
28 /**
29  * struct ad7303_state - driver instance specific data
30  * @spi:		the device for this driver instance
31  * @config:		cached config register value
32  * @dac_cache:		current DAC raw value (chip does not support readback)
33  * @vdd_reg:		reference to VDD regulator
34  * @vref_reg:		reference to VREF regulator
35  * @lock:		protect writes and cache updates
36  * @data:		spi transfer buffer
37  */
38 
39 struct ad7303_state {
40 	struct spi_device *spi;
41 	uint16_t config;
42 	uint8_t dac_cache[2];
43 
44 	struct regulator *vdd_reg;
45 	struct regulator *vref_reg;
46 
47 	struct mutex lock;
48 	/*
49 	 * DMA (thus cache coherency maintenance) requires the
50 	 * transfer buffers to live in their own cache lines.
51 	 */
52 	__be16 data ____cacheline_aligned;
53 };
54 
55 static int ad7303_write(struct ad7303_state *st, unsigned int chan,
56 	uint8_t val)
57 {
58 	st->data = cpu_to_be16(AD7303_CMD_UPDATE_DAC |
59 		(chan << AD7303_CFG_ADDR_OFFSET) |
60 		st->config | val);
61 
62 	return spi_write(st->spi, &st->data, sizeof(st->data));
63 }
64 
65 static ssize_t ad7303_read_dac_powerdown(struct iio_dev *indio_dev,
66 	uintptr_t private, const struct iio_chan_spec *chan, char *buf)
67 {
68 	struct ad7303_state *st = iio_priv(indio_dev);
69 
70 	return sprintf(buf, "%d\n", (bool)(st->config &
71 		AD7303_CFG_POWER_DOWN(chan->channel)));
72 }
73 
74 static ssize_t ad7303_write_dac_powerdown(struct iio_dev *indio_dev,
75 	 uintptr_t private, const struct iio_chan_spec *chan, const char *buf,
76 	 size_t len)
77 {
78 	struct ad7303_state *st = iio_priv(indio_dev);
79 	bool pwr_down;
80 	int ret;
81 
82 	ret = strtobool(buf, &pwr_down);
83 	if (ret)
84 		return ret;
85 
86 	mutex_lock(&st->lock);
87 
88 	if (pwr_down)
89 		st->config |= AD7303_CFG_POWER_DOWN(chan->channel);
90 	else
91 		st->config &= ~AD7303_CFG_POWER_DOWN(chan->channel);
92 
93 	/* There is no noop cmd which allows us to only update the powerdown
94 	 * mode, so just write one of the DAC channels again */
95 	ad7303_write(st, chan->channel, st->dac_cache[chan->channel]);
96 
97 	mutex_unlock(&st->lock);
98 	return len;
99 }
100 
101 static int ad7303_get_vref(struct ad7303_state *st,
102 	struct iio_chan_spec const *chan)
103 {
104 	int ret;
105 
106 	if (st->config & AD7303_CFG_EXTERNAL_VREF)
107 		return regulator_get_voltage(st->vref_reg);
108 
109 	ret = regulator_get_voltage(st->vdd_reg);
110 	if (ret < 0)
111 		return ret;
112 	return ret / 2;
113 }
114 
115 static int ad7303_read_raw(struct iio_dev *indio_dev,
116 	struct iio_chan_spec const *chan, int *val, int *val2, long info)
117 {
118 	struct ad7303_state *st = iio_priv(indio_dev);
119 	int vref_uv;
120 
121 	switch (info) {
122 	case IIO_CHAN_INFO_RAW:
123 		mutex_lock(&st->lock);
124 		*val = st->dac_cache[chan->channel];
125 		mutex_unlock(&st->lock);
126 		return IIO_VAL_INT;
127 	case IIO_CHAN_INFO_SCALE:
128 		vref_uv = ad7303_get_vref(st, chan);
129 		if (vref_uv < 0)
130 			return vref_uv;
131 
132 		*val = 2 * vref_uv / 1000;
133 		*val2 = chan->scan_type.realbits;
134 
135 		return IIO_VAL_FRACTIONAL_LOG2;
136 	default:
137 		break;
138 	}
139 	return -EINVAL;
140 }
141 
142 static int ad7303_write_raw(struct iio_dev *indio_dev,
143 	struct iio_chan_spec const *chan, int val, int val2, long mask)
144 {
145 	struct ad7303_state *st = iio_priv(indio_dev);
146 	int ret;
147 
148 	switch (mask) {
149 	case IIO_CHAN_INFO_RAW:
150 		if (val >= (1 << chan->scan_type.realbits) || val < 0)
151 			return -EINVAL;
152 
153 		mutex_lock(&st->lock);
154 		ret = ad7303_write(st, chan->address, val);
155 		if (ret == 0)
156 			st->dac_cache[chan->channel] = val;
157 		mutex_unlock(&st->lock);
158 		break;
159 	default:
160 		ret = -EINVAL;
161 	}
162 
163 	return ret;
164 }
165 
166 static const struct iio_info ad7303_info = {
167 	.read_raw = ad7303_read_raw,
168 	.write_raw = ad7303_write_raw,
169 };
170 
171 static const struct iio_chan_spec_ext_info ad7303_ext_info[] = {
172 	{
173 		.name = "powerdown",
174 		.read = ad7303_read_dac_powerdown,
175 		.write = ad7303_write_dac_powerdown,
176 		.shared = IIO_SEPARATE,
177 	},
178 	{ },
179 };
180 
181 #define AD7303_CHANNEL(chan) {					\
182 	.type = IIO_VOLTAGE,					\
183 	.indexed = 1,						\
184 	.output = 1,						\
185 	.channel = (chan),					\
186 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
187 	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
188 	.address = (chan),					\
189 	.scan_type = {						\
190 		.sign = 'u',					\
191 		.realbits = 8,					\
192 		.storagebits = 8,				\
193 		.shift = 0,					\
194 	},							\
195 	.ext_info = ad7303_ext_info,				\
196 }
197 
198 static const struct iio_chan_spec ad7303_channels[] = {
199 	AD7303_CHANNEL(0),
200 	AD7303_CHANNEL(1),
201 };
202 
203 static int ad7303_probe(struct spi_device *spi)
204 {
205 	const struct spi_device_id *id = spi_get_device_id(spi);
206 	struct iio_dev *indio_dev;
207 	struct ad7303_state *st;
208 	int ret;
209 
210 	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
211 	if (indio_dev == NULL)
212 		return -ENOMEM;
213 
214 	st = iio_priv(indio_dev);
215 	spi_set_drvdata(spi, indio_dev);
216 
217 	st->spi = spi;
218 
219 	mutex_init(&st->lock);
220 
221 	st->vdd_reg = devm_regulator_get(&spi->dev, "Vdd");
222 	if (IS_ERR(st->vdd_reg))
223 		return PTR_ERR(st->vdd_reg);
224 
225 	ret = regulator_enable(st->vdd_reg);
226 	if (ret)
227 		return ret;
228 
229 	st->vref_reg = devm_regulator_get_optional(&spi->dev, "REF");
230 	if (IS_ERR(st->vref_reg)) {
231 		ret = PTR_ERR(st->vref_reg);
232 		if (ret != -ENODEV)
233 			goto err_disable_vdd_reg;
234 		st->vref_reg = NULL;
235 	}
236 
237 	if (st->vref_reg) {
238 		ret = regulator_enable(st->vref_reg);
239 		if (ret)
240 			goto err_disable_vdd_reg;
241 
242 		st->config |= AD7303_CFG_EXTERNAL_VREF;
243 	}
244 
245 	indio_dev->name = id->name;
246 	indio_dev->info = &ad7303_info;
247 	indio_dev->modes = INDIO_DIRECT_MODE;
248 	indio_dev->channels = ad7303_channels;
249 	indio_dev->num_channels = ARRAY_SIZE(ad7303_channels);
250 
251 	ret = iio_device_register(indio_dev);
252 	if (ret)
253 		goto err_disable_vref_reg;
254 
255 	return 0;
256 
257 err_disable_vref_reg:
258 	if (st->vref_reg)
259 		regulator_disable(st->vref_reg);
260 err_disable_vdd_reg:
261 	regulator_disable(st->vdd_reg);
262 	return ret;
263 }
264 
265 static int ad7303_remove(struct spi_device *spi)
266 {
267 	struct iio_dev *indio_dev = spi_get_drvdata(spi);
268 	struct ad7303_state *st = iio_priv(indio_dev);
269 
270 	iio_device_unregister(indio_dev);
271 
272 	if (st->vref_reg)
273 		regulator_disable(st->vref_reg);
274 	regulator_disable(st->vdd_reg);
275 
276 	return 0;
277 }
278 
279 static const struct of_device_id ad7303_spi_of_match[] = {
280 	{ .compatible = "adi,ad7303", },
281 	{ /* sentinel */ },
282 };
283 MODULE_DEVICE_TABLE(of, ad7303_spi_of_match);
284 
285 static const struct spi_device_id ad7303_spi_ids[] = {
286 	{ "ad7303", 0 },
287 	{}
288 };
289 MODULE_DEVICE_TABLE(spi, ad7303_spi_ids);
290 
291 static struct spi_driver ad7303_driver = {
292 	.driver = {
293 		.name = "ad7303",
294 		.of_match_table = ad7303_spi_of_match,
295 	},
296 	.probe = ad7303_probe,
297 	.remove = ad7303_remove,
298 	.id_table = ad7303_spi_ids,
299 };
300 module_spi_driver(ad7303_driver);
301 
302 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
303 MODULE_DESCRIPTION("Analog Devices AD7303 DAC driver");
304 MODULE_LICENSE("GPL v2");
305