xref: /openbmc/linux/drivers/iio/dac/ad7303.c (revision 69e51448)
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