summaryrefslogtreecommitdiff
path: root/drivers/iio/adc/max11100.c
blob: a088cf99bfe12d69411c44fd4d095ec42647e7b2 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
/*
 * iio/adc/max11100.c
 * Maxim max11100 ADC Driver with IIO interface
 *
 * Copyright (C) 2016-17 Renesas Electronics Corporation
 * Copyright (C) 2016-17 Jacopo Mondi
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/regulator/consumer.h>
#include <linux/spi/spi.h>

#include <linux/iio/iio.h>
#include <linux/iio/driver.h>

/*
 * LSB is the ADC single digital step
 * 1 LSB = (vref_mv / 2 ^ 16)
 *
 * LSB is used to calculate analog voltage value
 * from the number of ADC steps count
 *
 * Ain = (count * LSB)
 */
#define MAX11100_LSB_DIV		(1 << 16)

struct max11100_state {
	struct regulator *vref_reg;
	struct spi_device *spi;

	/*
	 * DMA (thus cache coherency maintenance) requires the
	 * transfer buffers to live in their own cache lines.
	 */
	u8 buffer[3] ____cacheline_aligned;
};

static struct iio_chan_spec max11100_channels[] = {
	{ /* [0] */
		.type = IIO_VOLTAGE,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
				      BIT(IIO_CHAN_INFO_SCALE),
	},
};

static int max11100_read_single(struct iio_dev *indio_dev, int *val)
{
	int ret;
	struct max11100_state *state = iio_priv(indio_dev);

	ret = spi_read(state->spi, state->buffer, sizeof(state->buffer));
	if (ret) {
		dev_err(&indio_dev->dev, "SPI transfer failed\n");
		return ret;
	}

	/* the first 8 bits sent out from ADC must be 0s */
	if (state->buffer[0]) {
		dev_err(&indio_dev->dev, "Invalid value: buffer[0] != 0\n");
		return -EINVAL;
	}

	*val = (state->buffer[1] << 8) | state->buffer[2];

	return 0;
}

static int max11100_read_raw(struct iio_dev *indio_dev,
			     struct iio_chan_spec const *chan,
			     int *val, int *val2, long info)
{
	int ret, vref_uv;
	struct max11100_state *state = iio_priv(indio_dev);

	switch (info) {
	case IIO_CHAN_INFO_RAW:
		ret = max11100_read_single(indio_dev, val);
		if (ret)
			return ret;

		return IIO_VAL_INT;

	case IIO_CHAN_INFO_SCALE:
		vref_uv = regulator_get_voltage(state->vref_reg);
		if (vref_uv < 0)
			/* dummy regulator "get_voltage" returns -EINVAL */
			return -EINVAL;

		*val =  vref_uv / 1000;
		*val2 = MAX11100_LSB_DIV;
		return IIO_VAL_FRACTIONAL;
	}

	return -EINVAL;
}

static const struct iio_info max11100_info = {
	.driver_module = THIS_MODULE,
	.read_raw = max11100_read_raw,
};

static int max11100_probe(struct spi_device *spi)
{
	int ret;
	struct iio_dev *indio_dev;
	struct max11100_state *state;

	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state));
	if (!indio_dev)
		return -ENOMEM;

	spi_set_drvdata(spi, indio_dev);

	state = iio_priv(indio_dev);
	state->spi = spi;

	indio_dev->dev.parent = &spi->dev;
	indio_dev->dev.of_node = spi->dev.of_node;
	indio_dev->name = "max11100";
	indio_dev->info = &max11100_info;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->channels = max11100_channels,
	indio_dev->num_channels = ARRAY_SIZE(max11100_channels),

	state->vref_reg = devm_regulator_get(&spi->dev, "vref");
	if (IS_ERR(state->vref_reg))
		return PTR_ERR(state->vref_reg);

	ret = regulator_enable(state->vref_reg);
	if (ret)
		return ret;

	ret = iio_device_register(indio_dev);
	if (ret)
		goto disable_regulator;

	return 0;

disable_regulator:
	regulator_disable(state->vref_reg);

	return ret;
}

static int max11100_remove(struct spi_device *spi)
{
	struct iio_dev *indio_dev = spi_get_drvdata(spi);
	struct max11100_state *state = iio_priv(indio_dev);

	iio_device_unregister(indio_dev);
	regulator_disable(state->vref_reg);

	return 0;
}

static const struct of_device_id max11100_ids[] = {
	{.compatible = "maxim,max11100"},
	{ },
};
MODULE_DEVICE_TABLE(of, max11100_ids);

static struct spi_driver max11100_driver = {
	.driver = {
		.name	= "max11100",
		.owner	= THIS_MODULE,
		.of_match_table = of_match_ptr(max11100_ids),
	},
	.probe		= max11100_probe,
	.remove		= max11100_remove,
};

module_spi_driver(max11100_driver);

MODULE_AUTHOR("Jacopo Mondi <jacopo@jmondi.org>");
MODULE_DESCRIPTION("Maxim max11100 ADC Driver");
MODULE_LICENSE("GPL v2");