1/*
2 * Copyright (C) 2014 Angelo Compagnucci <angelo.compagnucci@gmail.com>
3 *
4 * Driver for Texas Instruments' ADC128S052 ADC chip.
5 * Datasheet can be found here:
6 * http://www.ti.com/lit/ds/symlink/adc128s052.pdf
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12
13#include <linux/err.h>
14#include <linux/spi/spi.h>
15#include <linux/module.h>
16#include <linux/iio/iio.h>
17#include <linux/regulator/consumer.h>
18
19struct adc128 {
20	struct spi_device *spi;
21
22	struct regulator *reg;
23	struct mutex lock;
24
25	u8 buffer[2] ____cacheline_aligned;
26};
27
28static int adc128_adc_conversion(struct adc128 *adc, u8 channel)
29{
30	int ret;
31
32	mutex_lock(&adc->lock);
33
34	adc->buffer[0] = channel << 3;
35	adc->buffer[1] = 0;
36
37	ret = spi_write(adc->spi, &adc->buffer, 2);
38	if (ret < 0) {
39		mutex_unlock(&adc->lock);
40		return ret;
41	}
42
43	ret = spi_read(adc->spi, &adc->buffer, 2);
44
45	mutex_unlock(&adc->lock);
46
47	if (ret < 0)
48		return ret;
49
50	return ((adc->buffer[0] << 8 | adc->buffer[1]) & 0xFFF);
51}
52
53static int adc128_read_raw(struct iio_dev *indio_dev,
54			   struct iio_chan_spec const *channel, int *val,
55			   int *val2, long mask)
56{
57	struct adc128 *adc = iio_priv(indio_dev);
58	int ret;
59
60	switch (mask) {
61	case IIO_CHAN_INFO_RAW:
62
63		ret = adc128_adc_conversion(adc, channel->channel);
64		if (ret < 0)
65			return ret;
66
67		*val = ret;
68		return IIO_VAL_INT;
69
70	case IIO_CHAN_INFO_SCALE:
71
72		ret = regulator_get_voltage(adc->reg);
73		if (ret < 0)
74			return ret;
75
76		*val = ret / 1000;
77		*val2 = 12;
78		return IIO_VAL_FRACTIONAL_LOG2;
79
80	default:
81		return -EINVAL;
82	}
83
84}
85
86#define ADC128_VOLTAGE_CHANNEL(num)	\
87	{ \
88		.type = IIO_VOLTAGE, \
89		.indexed = 1, \
90		.channel = (num), \
91		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
92		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \
93	}
94
95static const struct iio_chan_spec adc128_channels[] = {
96	ADC128_VOLTAGE_CHANNEL(0),
97	ADC128_VOLTAGE_CHANNEL(1),
98	ADC128_VOLTAGE_CHANNEL(2),
99	ADC128_VOLTAGE_CHANNEL(3),
100	ADC128_VOLTAGE_CHANNEL(4),
101	ADC128_VOLTAGE_CHANNEL(5),
102	ADC128_VOLTAGE_CHANNEL(6),
103	ADC128_VOLTAGE_CHANNEL(7),
104};
105
106static const struct iio_info adc128_info = {
107	.read_raw = adc128_read_raw,
108	.driver_module = THIS_MODULE,
109};
110
111static int adc128_probe(struct spi_device *spi)
112{
113	struct iio_dev *indio_dev;
114	struct adc128 *adc;
115	int ret;
116
117	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
118	if (!indio_dev)
119		return -ENOMEM;
120
121	adc = iio_priv(indio_dev);
122	adc->spi = spi;
123
124	spi_set_drvdata(spi, indio_dev);
125
126	indio_dev->dev.parent = &spi->dev;
127	indio_dev->name = spi_get_device_id(spi)->name;
128	indio_dev->modes = INDIO_DIRECT_MODE;
129	indio_dev->info = &adc128_info;
130
131	indio_dev->channels = adc128_channels;
132	indio_dev->num_channels = ARRAY_SIZE(adc128_channels);
133
134	adc->reg = devm_regulator_get(&spi->dev, "vref");
135	if (IS_ERR(adc->reg))
136		return PTR_ERR(adc->reg);
137
138	ret = regulator_enable(adc->reg);
139	if (ret < 0)
140		return ret;
141
142	mutex_init(&adc->lock);
143
144	ret = iio_device_register(indio_dev);
145
146	return ret;
147}
148
149static int adc128_remove(struct spi_device *spi)
150{
151	struct iio_dev *indio_dev = spi_get_drvdata(spi);
152	struct adc128 *adc = iio_priv(indio_dev);
153
154	iio_device_unregister(indio_dev);
155	regulator_disable(adc->reg);
156
157	return 0;
158}
159
160static const struct spi_device_id adc128_id[] = {
161	{ "adc128s052", 0},
162	{ }
163};
164MODULE_DEVICE_TABLE(spi, adc128_id);
165
166static struct spi_driver adc128_driver = {
167	.driver = {
168		.name = "adc128s052",
169		.owner = THIS_MODULE,
170	},
171	.probe = adc128_probe,
172	.remove = adc128_remove,
173	.id_table = adc128_id,
174};
175module_spi_driver(adc128_driver);
176
177MODULE_AUTHOR("Angelo Compagnucci <angelo.compagnucci@gmail.com>");
178MODULE_DESCRIPTION("Texas Instruments ADC128S052");
179MODULE_LICENSE("GPL v2");
180