1/*
2 * AD7303 Digital to analog converters driver
3 *
4 * Copyright 2013 Analog Devices Inc.
5 *
6 * Licensed under the GPL-2.
7 */
8
9#include <linux/err.h>
10#include <linux/module.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#include <linux/of.h>
17
18#include <linux/iio/iio.h>
19#include <linux/iio/sysfs.h>
20
21#include <linux/platform_data/ad7303.h>
22
23#define AD7303_CFG_EXTERNAL_VREF BIT(15)
24#define AD7303_CFG_POWER_DOWN(ch) BIT(11 + (ch))
25#define AD7303_CFG_ADDR_OFFSET	10
26
27#define AD7303_CMD_UPDATE_DAC	(0x3 << 8)
28
29/**
30 * struct ad7303_state - driver instance specific data
31 * @spi:		the device for this driver instance
32 * @config:		cached config register value
33 * @dac_cache:		current DAC raw value (chip does not support readback)
34 * @data:		spi transfer buffer
35 */
36
37struct 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	/*
46	 * DMA (thus cache coherency maintenance) requires the
47	 * transfer buffers to live in their own cache lines.
48	 */
49	__be16 data ____cacheline_aligned;
50};
51
52static int ad7303_write(struct ad7303_state *st, unsigned int chan,
53	uint8_t val)
54{
55	st->data = cpu_to_be16(AD7303_CMD_UPDATE_DAC |
56		(chan << AD7303_CFG_ADDR_OFFSET) |
57		st->config | val);
58
59	return spi_write(st->spi, &st->data, sizeof(st->data));
60}
61
62static ssize_t ad7303_read_dac_powerdown(struct iio_dev *indio_dev,
63	uintptr_t private, const struct iio_chan_spec *chan, char *buf)
64{
65	struct ad7303_state *st = iio_priv(indio_dev);
66
67	return sprintf(buf, "%d\n", (bool)(st->config &
68		AD7303_CFG_POWER_DOWN(chan->channel)));
69}
70
71static ssize_t ad7303_write_dac_powerdown(struct iio_dev *indio_dev,
72	 uintptr_t private, const struct iio_chan_spec *chan, const char *buf,
73	 size_t len)
74{
75	struct ad7303_state *st = iio_priv(indio_dev);
76	bool pwr_down;
77	int ret;
78
79	ret = strtobool(buf, &pwr_down);
80	if (ret)
81		return ret;
82
83	mutex_lock(&indio_dev->mlock);
84
85	if (pwr_down)
86		st->config |= AD7303_CFG_POWER_DOWN(chan->channel);
87	else
88		st->config &= ~AD7303_CFG_POWER_DOWN(chan->channel);
89
90	/* There is no noop cmd which allows us to only update the powerdown
91	 * mode, so just write one of the DAC channels again */
92	ad7303_write(st, chan->channel, st->dac_cache[chan->channel]);
93
94	mutex_unlock(&indio_dev->mlock);
95	return len;
96}
97
98static int ad7303_get_vref(struct ad7303_state *st,
99	struct iio_chan_spec const *chan)
100{
101	int ret;
102
103	if (st->config & AD7303_CFG_EXTERNAL_VREF)
104		return regulator_get_voltage(st->vref_reg);
105
106	ret = regulator_get_voltage(st->vdd_reg);
107	if (ret < 0)
108		return ret;
109	return ret / 2;
110}
111
112static int ad7303_read_raw(struct iio_dev *indio_dev,
113	struct iio_chan_spec const *chan, int *val, int *val2, long info)
114{
115	struct ad7303_state *st = iio_priv(indio_dev);
116	int vref_uv;
117
118	switch (info) {
119	case IIO_CHAN_INFO_RAW:
120		*val = st->dac_cache[chan->channel];
121		return IIO_VAL_INT;
122	case IIO_CHAN_INFO_SCALE:
123		vref_uv = ad7303_get_vref(st, chan);
124		if (vref_uv < 0)
125			return vref_uv;
126
127		*val = 2 * vref_uv / 1000;
128		*val2 = chan->scan_type.realbits;
129
130		return IIO_VAL_FRACTIONAL_LOG2;
131	default:
132		break;
133	}
134	return -EINVAL;
135}
136
137static int ad7303_write_raw(struct iio_dev *indio_dev,
138	struct iio_chan_spec const *chan, int val, int val2, long mask)
139{
140	struct ad7303_state *st = iio_priv(indio_dev);
141	int ret;
142
143	switch (mask) {
144	case IIO_CHAN_INFO_RAW:
145		if (val >= (1 << chan->scan_type.realbits) || val < 0)
146			return -EINVAL;
147
148		mutex_lock(&indio_dev->mlock);
149		ret = ad7303_write(st, chan->address, val);
150		if (ret == 0)
151			st->dac_cache[chan->channel] = val;
152		mutex_unlock(&indio_dev->mlock);
153		break;
154	default:
155		ret = -EINVAL;
156	}
157
158	return ret;
159}
160
161static const struct iio_info ad7303_info = {
162	.read_raw = ad7303_read_raw,
163	.write_raw = ad7303_write_raw,
164	.driver_module = THIS_MODULE,
165};
166
167static const struct iio_chan_spec_ext_info ad7303_ext_info[] = {
168	{
169		.name = "powerdown",
170		.read = ad7303_read_dac_powerdown,
171		.write = ad7303_write_dac_powerdown,
172		.shared = IIO_SEPARATE,
173	},
174	{ },
175};
176
177#define AD7303_CHANNEL(chan) {					\
178	.type = IIO_VOLTAGE,					\
179	.indexed = 1,						\
180	.output = 1,						\
181	.channel = (chan),					\
182	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
183	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
184	.address = (chan),					\
185	.scan_type = {						\
186		.sign = 'u',					\
187		.realbits = '8',				\
188		.storagebits = '8',				\
189		.shift = '0',					\
190	},							\
191	.ext_info = ad7303_ext_info,				\
192}
193
194static const struct iio_chan_spec ad7303_channels[] = {
195	AD7303_CHANNEL(0),
196	AD7303_CHANNEL(1),
197};
198
199static int ad7303_probe(struct spi_device *spi)
200{
201	const struct spi_device_id *id = spi_get_device_id(spi);
202	struct iio_dev *indio_dev;
203	struct ad7303_state *st;
204	bool ext_ref;
205	int ret;
206
207	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
208	if (indio_dev == NULL)
209		return -ENOMEM;
210
211	st = iio_priv(indio_dev);
212	spi_set_drvdata(spi, indio_dev);
213
214	st->spi = spi;
215
216	st->vdd_reg = devm_regulator_get(&spi->dev, "Vdd");
217	if (IS_ERR(st->vdd_reg))
218		return PTR_ERR(st->vdd_reg);
219
220	ret = regulator_enable(st->vdd_reg);
221	if (ret)
222		return ret;
223
224	if (spi->dev.of_node) {
225		ext_ref = of_property_read_bool(spi->dev.of_node,
226				"REF-supply");
227	} else {
228		struct ad7303_platform_data *pdata = spi->dev.platform_data;
229		if (pdata && pdata->use_external_ref)
230			ext_ref = true;
231		else
232		    ext_ref = false;
233	}
234
235	if (ext_ref) {
236		st->vref_reg = devm_regulator_get(&spi->dev, "REF");
237		if (IS_ERR(st->vref_reg)) {
238			ret = PTR_ERR(st->vref_reg);
239			goto err_disable_vdd_reg;
240		}
241
242		ret = regulator_enable(st->vref_reg);
243		if (ret)
244			goto err_disable_vdd_reg;
245
246		st->config |= AD7303_CFG_EXTERNAL_VREF;
247	}
248
249	indio_dev->dev.parent = &spi->dev;
250	indio_dev->name = id->name;
251	indio_dev->info = &ad7303_info;
252	indio_dev->modes = INDIO_DIRECT_MODE;
253	indio_dev->channels = ad7303_channels;
254	indio_dev->num_channels = ARRAY_SIZE(ad7303_channels);
255
256	ret = iio_device_register(indio_dev);
257	if (ret)
258		goto err_disable_vref_reg;
259
260	return 0;
261
262err_disable_vref_reg:
263	if (st->vref_reg)
264		regulator_disable(st->vref_reg);
265err_disable_vdd_reg:
266	regulator_disable(st->vdd_reg);
267	return ret;
268}
269
270static int ad7303_remove(struct spi_device *spi)
271{
272	struct iio_dev *indio_dev = spi_get_drvdata(spi);
273	struct ad7303_state *st = iio_priv(indio_dev);
274
275	iio_device_unregister(indio_dev);
276
277	if (st->vref_reg)
278		regulator_disable(st->vref_reg);
279	regulator_disable(st->vdd_reg);
280
281	return 0;
282}
283
284static const struct spi_device_id ad7303_spi_ids[] = {
285	{ "ad7303", 0 },
286	{}
287};
288MODULE_DEVICE_TABLE(spi, ad7303_spi_ids);
289
290static struct spi_driver ad7303_driver = {
291	.driver = {
292		.name = "ad7303",
293		.owner = THIS_MODULE,
294	},
295	.probe = ad7303_probe,
296	.remove = ad7303_remove,
297	.id_table = ad7303_spi_ids,
298};
299module_spi_driver(ad7303_driver);
300
301MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
302MODULE_DESCRIPTION("Analog Devices AD7303 DAC driver");
303MODULE_LICENSE("GPL v2");
304