aboutsummaryrefslogtreecommitdiff
path: root/drivers/iio/dac/mcp4922.c
blob: c4e430b4050e1fa0215dc32dcf9ee227e1d66060 (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
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * mcp4922.c
 *
 * Driver for Microchip Digital to Analog Converters.
 * Supports MCP4902, MCP4912, and MCP4922.
 *
 * Copyright (c) 2014 EMAC Inc.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/spi/spi.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/regulator/consumer.h>
#include <linux/bitops.h>

#define MCP4922_NUM_CHANNELS	2

enum mcp4922_supported_device_ids {
	ID_MCP4902,
	ID_MCP4912,
	ID_MCP4922,
};

struct mcp4922_state {
	struct spi_device *spi;
	unsigned int value[MCP4922_NUM_CHANNELS];
	unsigned int vref_mv;
	struct regulator *vref_reg;
	u8 mosi[2] ____cacheline_aligned;
};

#define MCP4922_CHAN(chan, bits) {			\
	.type = IIO_VOLTAGE,				\
	.output = 1,					\
	.indexed = 1,					\
	.channel = chan,				\
	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
	.scan_type = {					\
		.sign = 'u',				\
		.realbits = (bits),			\
		.storagebits = 16,			\
		.shift = 12 - (bits),			\
	},						\
}

static int mcp4922_spi_write(struct mcp4922_state *state, u8 addr, u32 val)
{
	state->mosi[1] = val & 0xff;
	state->mosi[0] = (addr == 0) ? 0x00 : 0x80;
	state->mosi[0] |= 0x30 | ((val >> 8) & 0x0f);

	return spi_write(state->spi, state->mosi, 2);
}

static int mcp4922_read_raw(struct iio_dev *indio_dev,
		struct iio_chan_spec const *chan,
		int *val,
		int *val2,
		long mask)
{
	struct mcp4922_state *state = iio_priv(indio_dev);

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		*val = state->value[chan->channel];
		return IIO_VAL_INT;
	case IIO_CHAN_INFO_SCALE:
		*val = state->vref_mv;
		*val2 = chan->scan_type.realbits;
		return IIO_VAL_FRACTIONAL_LOG2;
	default:
		return -EINVAL;
	}
}

static int mcp4922_write_raw(struct iio_dev *indio_dev,
		struct iio_chan_spec const *chan,
		int val,
		int val2,
		long mask)
{
	struct mcp4922_state *state = iio_priv(indio_dev);
	int ret;

	if (val2 != 0)
		return -EINVAL;

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		if (val < 0 || val > GENMASK(chan->scan_type.realbits - 1, 0))
			return -EINVAL;
		val <<= chan->scan_type.shift;

		ret = mcp4922_spi_write(state, chan->channel, val);
		if (!ret)
			state->value[chan->channel] = val;
		return ret;

	default:
		return -EINVAL;
	}
}

static const struct iio_chan_spec mcp4922_channels[3][MCP4922_NUM_CHANNELS] = {
	[ID_MCP4902] = { MCP4922_CHAN(0, 8),	MCP4922_CHAN(1, 8) },
	[ID_MCP4912] = { MCP4922_CHAN(0, 10),	MCP4922_CHAN(1, 10) },
	[ID_MCP4922] = { MCP4922_CHAN(0, 12),	MCP4922_CHAN(1, 12) },
};

static const struct iio_info mcp4922_info = {
	.read_raw = &mcp4922_read_raw,
	.write_raw = &mcp4922_write_raw,
};

static int mcp4922_probe(struct spi_device *spi)
{
	struct iio_dev *indio_dev;
	struct mcp4922_state *state;
	const struct spi_device_id *id;
	int ret;

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

	state = iio_priv(indio_dev);
	state->spi = spi;
	state->vref_reg = devm_regulator_get(&spi->dev, "vref");
	if (IS_ERR(state->vref_reg)) {
		dev_err(&spi->dev, "Vref regulator not specified\n");
		return PTR_ERR(state->vref_reg);
	}

	ret = regulator_enable(state->vref_reg);
	if (ret) {
		dev_err(&spi->dev, "Failed to enable vref regulator: %d\n",
				ret);
		return ret;
	}

	ret = regulator_get_voltage(state->vref_reg);
	if (ret < 0) {
		dev_err(&spi->dev, "Failed to read vref regulator: %d\n",
				ret);
		goto error_disable_reg;
	}
	state->vref_mv = ret / 1000;

	spi_set_drvdata(spi, indio_dev);
	id = spi_get_device_id(spi);
	indio_dev->info = &mcp4922_info;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->channels = mcp4922_channels[id->driver_data];
	indio_dev->num_channels = MCP4922_NUM_CHANNELS;
	indio_dev->name = id->name;

	ret = iio_device_register(indio_dev);
	if (ret) {
		dev_err(&spi->dev, "Failed to register iio device: %d\n",
				ret);
		goto error_disable_reg;
	}

	return 0;

error_disable_reg:
	regulator_disable(state->vref_reg);

	return ret;
}

static int mcp4922_remove(struct spi_device *spi)
{
	struct iio_dev *indio_dev = spi_get_drvdata(spi);
	struct mcp4922_state *state;

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

	return 0;
}

static const struct spi_device_id mcp4922_id[] = {
	{"mcp4902", ID_MCP4902},
	{"mcp4912", ID_MCP4912},
	{"mcp4922", ID_MCP4922},
	{}
};
MODULE_DEVICE_TABLE(spi, mcp4922_id);

static struct spi_driver mcp4922_driver = {
	.driver = {
		   .name = "mcp4922",
		   },
	.probe = mcp4922_probe,
	.remove = mcp4922_remove,
	.id_table = mcp4922_id,
};
module_spi_driver(mcp4922_driver);

MODULE_AUTHOR("Michael Welling <mwelling@ieee.org>");
MODULE_DESCRIPTION("Microchip MCP4902, MCP4912, MCP4922 DAC");
MODULE_LICENSE("GPL v2");