1/*
2 * Copyright (C) 2014 Angelo Compagnucci <angelo.compagnucci@gmail.com>
3 *
4 * Driver for Texas Instruments' ADC128S052 and ADC122S021 ADC chip.
5 * Datasheets can be found here:
6 * http://www.ti.com/lit/ds/symlink/adc128s052.pdf
7 * http://www.ti.com/lit/ds/symlink/adc122s021.pdf
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
12 */
13
14#include <linux/err.h>
15#include <linux/spi/spi.h>
16#include <linux/module.h>
17#include <linux/iio/iio.h>
18#include <linux/regulator/consumer.h>
19
20struct adc128_configuration {
21	const struct iio_chan_spec	*channels;
22	u8				num_channels;
23};
24
25struct adc128 {
26	struct spi_device *spi;
27
28	struct regulator *reg;
29	struct mutex lock;
30
31	u8 buffer[2] ____cacheline_aligned;
32};
33
34static int adc128_adc_conversion(struct adc128 *adc, u8 channel)
35{
36	int ret;
37
38	mutex_lock(&adc->lock);
39
40	adc->buffer[0] = channel << 3;
41	adc->buffer[1] = 0;
42
43	ret = spi_write(adc->spi, &adc->buffer, 2);
44	if (ret < 0) {
45		mutex_unlock(&adc->lock);
46		return ret;
47	}
48
49	ret = spi_read(adc->spi, &adc->buffer, 2);
50
51	mutex_unlock(&adc->lock);
52
53	if (ret < 0)
54		return ret;
55
56	return ((adc->buffer[0] << 8 | adc->buffer[1]) & 0xFFF);
57}
58
59static int adc128_read_raw(struct iio_dev *indio_dev,
60			   struct iio_chan_spec const *channel, int *val,
61			   int *val2, long mask)
62{
63	struct adc128 *adc = iio_priv(indio_dev);
64	int ret;
65
66	switch (mask) {
67	case IIO_CHAN_INFO_RAW:
68
69		ret = adc128_adc_conversion(adc, channel->channel);
70		if (ret < 0)
71			return ret;
72
73		*val = ret;
74		return IIO_VAL_INT;
75
76	case IIO_CHAN_INFO_SCALE:
77
78		ret = regulator_get_voltage(adc->reg);
79		if (ret < 0)
80			return ret;
81
82		*val = ret / 1000;
83		*val2 = 12;
84		return IIO_VAL_FRACTIONAL_LOG2;
85
86	default:
87		return -EINVAL;
88	}
89
90}
91
92#define ADC128_VOLTAGE_CHANNEL(num)	\
93	{ \
94		.type = IIO_VOLTAGE, \
95		.indexed = 1, \
96		.channel = (num), \
97		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
98		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) \
99	}
100
101static const struct iio_chan_spec adc128s052_channels[] = {
102	ADC128_VOLTAGE_CHANNEL(0),
103	ADC128_VOLTAGE_CHANNEL(1),
104	ADC128_VOLTAGE_CHANNEL(2),
105	ADC128_VOLTAGE_CHANNEL(3),
106	ADC128_VOLTAGE_CHANNEL(4),
107	ADC128_VOLTAGE_CHANNEL(5),
108	ADC128_VOLTAGE_CHANNEL(6),
109	ADC128_VOLTAGE_CHANNEL(7),
110};
111
112static const struct iio_chan_spec adc122s021_channels[] = {
113	ADC128_VOLTAGE_CHANNEL(0),
114	ADC128_VOLTAGE_CHANNEL(1),
115};
116
117static const struct adc128_configuration adc128_config[] = {
118	{ adc128s052_channels, ARRAY_SIZE(adc128s052_channels) },
119	{ adc122s021_channels, ARRAY_SIZE(adc122s021_channels) },
120};
121
122static const struct iio_info adc128_info = {
123	.read_raw = adc128_read_raw,
124	.driver_module = THIS_MODULE,
125};
126
127static int adc128_probe(struct spi_device *spi)
128{
129	struct iio_dev *indio_dev;
130	struct adc128 *adc;
131	int config = spi_get_device_id(spi)->driver_data;
132	int ret;
133
134	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
135	if (!indio_dev)
136		return -ENOMEM;
137
138	adc = iio_priv(indio_dev);
139	adc->spi = spi;
140
141	spi_set_drvdata(spi, indio_dev);
142
143	indio_dev->dev.parent = &spi->dev;
144	indio_dev->name = spi_get_device_id(spi)->name;
145	indio_dev->modes = INDIO_DIRECT_MODE;
146	indio_dev->info = &adc128_info;
147
148	indio_dev->channels = adc128_config[config].channels;
149	indio_dev->num_channels = adc128_config[config].num_channels;
150
151	adc->reg = devm_regulator_get(&spi->dev, "vref");
152	if (IS_ERR(adc->reg))
153		return PTR_ERR(adc->reg);
154
155	ret = regulator_enable(adc->reg);
156	if (ret < 0)
157		return ret;
158
159	mutex_init(&adc->lock);
160
161	ret = iio_device_register(indio_dev);
162
163	return ret;
164}
165
166static int adc128_remove(struct spi_device *spi)
167{
168	struct iio_dev *indio_dev = spi_get_drvdata(spi);
169	struct adc128 *adc = iio_priv(indio_dev);
170
171	iio_device_unregister(indio_dev);
172	regulator_disable(adc->reg);
173
174	return 0;
175}
176
177static const struct of_device_id adc128_of_match[] = {
178	{ .compatible = "ti,adc128s052", },
179	{ .compatible = "ti,adc122s021", },
180	{ /* sentinel */ },
181};
182MODULE_DEVICE_TABLE(of, adc128_of_match);
183
184static const struct spi_device_id adc128_id[] = {
185	{ "adc128s052", 0},	/* index into adc128_config */
186	{ "adc122s021",	1},
187	{ }
188};
189MODULE_DEVICE_TABLE(spi, adc128_id);
190
191static struct spi_driver adc128_driver = {
192	.driver = {
193		.name = "adc128s052",
194		.of_match_table = of_match_ptr(adc128_of_match),
195	},
196	.probe = adc128_probe,
197	.remove = adc128_remove,
198	.id_table = adc128_id,
199};
200module_spi_driver(adc128_driver);
201
202MODULE_AUTHOR("Angelo Compagnucci <angelo.compagnucci@gmail.com>");
203MODULE_DESCRIPTION("Texas Instruments ADC128S052");
204MODULE_LICENSE("GPL v2");
205