1/*
2 * AD8366 SPI Dual-Digital Variable Gain Amplifier (VGA)
3 *
4 * Copyright 2012 Analog Devices Inc.
5 *
6 * Licensed under the GPL-2.
7 */
8
9#include <linux/device.h>
10#include <linux/kernel.h>
11#include <linux/slab.h>
12#include <linux/sysfs.h>
13#include <linux/spi/spi.h>
14#include <linux/regulator/consumer.h>
15#include <linux/err.h>
16#include <linux/module.h>
17#include <linux/bitrev.h>
18
19#include <linux/iio/iio.h>
20#include <linux/iio/sysfs.h>
21
22struct ad8366_state {
23	struct spi_device	*spi;
24	struct regulator	*reg;
25	unsigned char		ch[2];
26	/*
27	 * DMA (thus cache coherency maintenance) requires the
28	 * transfer buffers to live in their own cache lines.
29	 */
30	unsigned char		data[2] ____cacheline_aligned;
31};
32
33static int ad8366_write(struct iio_dev *indio_dev,
34			unsigned char ch_a, unsigned char ch_b)
35{
36	struct ad8366_state *st = iio_priv(indio_dev);
37	int ret;
38
39	ch_a = bitrev8(ch_a & 0x3F);
40	ch_b = bitrev8(ch_b & 0x3F);
41
42	st->data[0] = ch_b >> 4;
43	st->data[1] = (ch_b << 4) | (ch_a >> 2);
44
45	ret = spi_write(st->spi, st->data, ARRAY_SIZE(st->data));
46	if (ret < 0)
47		dev_err(&indio_dev->dev, "write failed (%d)", ret);
48
49	return ret;
50}
51
52static int ad8366_read_raw(struct iio_dev *indio_dev,
53			   struct iio_chan_spec const *chan,
54			   int *val,
55			   int *val2,
56			   long m)
57{
58	struct ad8366_state *st = iio_priv(indio_dev);
59	int ret;
60	unsigned code;
61
62	mutex_lock(&indio_dev->mlock);
63	switch (m) {
64	case IIO_CHAN_INFO_HARDWAREGAIN:
65		code = st->ch[chan->channel];
66
67		/* Values in dB */
68		code = code * 253 + 4500;
69		*val = code / 1000;
70		*val2 = (code % 1000) * 1000;
71
72		ret = IIO_VAL_INT_PLUS_MICRO_DB;
73		break;
74	default:
75		ret = -EINVAL;
76	}
77	mutex_unlock(&indio_dev->mlock);
78
79	return ret;
80};
81
82static int ad8366_write_raw(struct iio_dev *indio_dev,
83			    struct iio_chan_spec const *chan,
84			    int val,
85			    int val2,
86			    long mask)
87{
88	struct ad8366_state *st = iio_priv(indio_dev);
89	unsigned code;
90	int ret;
91
92	if (val < 0 || val2 < 0)
93		return -EINVAL;
94
95	/* Values in dB */
96	code = (((u8)val * 1000) + ((u32)val2 / 1000));
97
98	if (code > 20500 || code < 4500)
99		return -EINVAL;
100
101	code = (code - 4500) / 253;
102
103	mutex_lock(&indio_dev->mlock);
104	switch (mask) {
105	case IIO_CHAN_INFO_HARDWAREGAIN:
106		st->ch[chan->channel] = code;
107		ret = ad8366_write(indio_dev, st->ch[0], st->ch[1]);
108		break;
109	default:
110		ret = -EINVAL;
111	}
112	mutex_unlock(&indio_dev->mlock);
113
114	return ret;
115}
116
117static const struct iio_info ad8366_info = {
118	.read_raw = &ad8366_read_raw,
119	.write_raw = &ad8366_write_raw,
120	.driver_module = THIS_MODULE,
121};
122
123#define AD8366_CHAN(_channel) {				\
124	.type = IIO_VOLTAGE,				\
125	.output = 1,					\
126	.indexed = 1,					\
127	.channel = _channel,				\
128	.info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN),\
129}
130
131static const struct iio_chan_spec ad8366_channels[] = {
132	AD8366_CHAN(0),
133	AD8366_CHAN(1),
134};
135
136static int ad8366_probe(struct spi_device *spi)
137{
138	struct iio_dev *indio_dev;
139	struct ad8366_state *st;
140	int ret;
141
142	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
143	if (indio_dev == NULL)
144		return -ENOMEM;
145
146	st = iio_priv(indio_dev);
147
148	st->reg = devm_regulator_get(&spi->dev, "vcc");
149	if (!IS_ERR(st->reg)) {
150		ret = regulator_enable(st->reg);
151		if (ret)
152			return ret;
153	}
154
155	spi_set_drvdata(spi, indio_dev);
156	st->spi = spi;
157
158	indio_dev->dev.parent = &spi->dev;
159	indio_dev->name = spi_get_device_id(spi)->name;
160	indio_dev->info = &ad8366_info;
161	indio_dev->modes = INDIO_DIRECT_MODE;
162	indio_dev->channels = ad8366_channels;
163	indio_dev->num_channels = ARRAY_SIZE(ad8366_channels);
164
165	ret = iio_device_register(indio_dev);
166	if (ret)
167		goto error_disable_reg;
168
169	ad8366_write(indio_dev, 0, 0);
170
171	return 0;
172
173error_disable_reg:
174	if (!IS_ERR(st->reg))
175		regulator_disable(st->reg);
176
177	return ret;
178}
179
180static int ad8366_remove(struct spi_device *spi)
181{
182	struct iio_dev *indio_dev = spi_get_drvdata(spi);
183	struct ad8366_state *st = iio_priv(indio_dev);
184	struct regulator *reg = st->reg;
185
186	iio_device_unregister(indio_dev);
187
188	if (!IS_ERR(reg))
189		regulator_disable(reg);
190
191	return 0;
192}
193
194static const struct spi_device_id ad8366_id[] = {
195	{"ad8366", 0},
196	{}
197};
198
199static struct spi_driver ad8366_driver = {
200	.driver = {
201		.name	= KBUILD_MODNAME,
202		.owner	= THIS_MODULE,
203	},
204	.probe		= ad8366_probe,
205	.remove		= ad8366_remove,
206	.id_table	= ad8366_id,
207};
208
209module_spi_driver(ad8366_driver);
210
211MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
212MODULE_DESCRIPTION("Analog Devices AD8366 VGA");
213MODULE_LICENSE("GPL v2");
214