1/*
2 * mcp4922.c
3 *
4 * Driver for Microchip Digital to Analog Converters.
5 * Supports MCP4902, MCP4912, and MCP4922.
6 *
7 * Copyright (c) 2014 EMAC Inc.
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 as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
17 * GNU General Public License for more details.
18 *
19 */
20
21#include <linux/module.h>
22#include <linux/init.h>
23#include <linux/spi/spi.h>
24#include <linux/iio/iio.h>
25#include <linux/iio/sysfs.h>
26#include <linux/regulator/consumer.h>
27#include <linux/bitops.h>
28
29#define MCP4922_NUM_CHANNELS	2
30
31enum mcp4922_supported_device_ids {
32	ID_MCP4902,
33	ID_MCP4912,
34	ID_MCP4922,
35};
36
37struct mcp4922_state {
38	struct spi_device *spi;
39	unsigned int value[MCP4922_NUM_CHANNELS];
40	unsigned int vref_mv;
41	struct regulator *vref_reg;
42	u8 mosi[2] ____cacheline_aligned;
43};
44
45#define MCP4922_CHAN(chan, bits) {			\
46	.type = IIO_VOLTAGE,				\
47	.output = 1,					\
48	.indexed = 1,					\
49	.channel = chan,				\
50	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
51	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
52	.scan_type = {					\
53		.sign = 'u',				\
54		.realbits = (bits),			\
55		.storagebits = 16,			\
56		.shift = 12 - (bits),			\
57	},						\
58}
59
60static int mcp4922_spi_write(struct mcp4922_state *state, u8 addr, u32 val)
61{
62	state->mosi[1] = val & 0xff;
63	state->mosi[0] = (addr == 0) ? 0x00 : 0x80;
64	state->mosi[0] |= 0x30 | ((val >> 8) & 0x0f);
65
66	return spi_write(state->spi, state->mosi, 2);
67}
68
69static int mcp4922_read_raw(struct iio_dev *indio_dev,
70		struct iio_chan_spec const *chan,
71		int *val,
72		int *val2,
73		long mask)
74{
75	struct mcp4922_state *state = iio_priv(indio_dev);
76
77	switch (mask) {
78	case IIO_CHAN_INFO_RAW:
79		*val = state->value[chan->channel];
80		return IIO_VAL_INT;
81	case IIO_CHAN_INFO_SCALE:
82		*val = state->vref_mv;
83		*val2 = chan->scan_type.realbits;
84		return IIO_VAL_FRACTIONAL_LOG2;
85	default:
86		return -EINVAL;
87	}
88}
89
90static int mcp4922_write_raw(struct iio_dev *indio_dev,
91		struct iio_chan_spec const *chan,
92		int val,
93		int val2,
94		long mask)
95{
96	struct mcp4922_state *state = iio_priv(indio_dev);
97
98	if (val2 != 0)
99		return -EINVAL;
100
101	switch (mask) {
102	case IIO_CHAN_INFO_RAW:
103		if (val > GENMASK(chan->scan_type.realbits-1, 0))
104			return -EINVAL;
105		val <<= chan->scan_type.shift;
106		state->value[chan->channel] = val;
107		return mcp4922_spi_write(state, chan->channel, val);
108	default:
109		return -EINVAL;
110	}
111}
112
113static const struct iio_chan_spec mcp4922_channels[3][MCP4922_NUM_CHANNELS] = {
114	[ID_MCP4902] = { MCP4922_CHAN(0, 8),	MCP4922_CHAN(1, 8) },
115	[ID_MCP4912] = { MCP4922_CHAN(0, 10),	MCP4922_CHAN(1, 10) },
116	[ID_MCP4922] = { MCP4922_CHAN(0, 12),	MCP4922_CHAN(1, 12) },
117};
118
119static const struct iio_info mcp4922_info = {
120	.read_raw = &mcp4922_read_raw,
121	.write_raw = &mcp4922_write_raw,
122	.driver_module = THIS_MODULE,
123};
124
125static int mcp4922_probe(struct spi_device *spi)
126{
127	struct iio_dev *indio_dev;
128	struct mcp4922_state *state;
129	const struct spi_device_id *id;
130	int ret;
131
132	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state));
133	if (indio_dev == NULL)
134		return -ENOMEM;
135
136	state = iio_priv(indio_dev);
137	state->spi = spi;
138	state->vref_reg = devm_regulator_get(&spi->dev, "vref");
139	if (IS_ERR(state->vref_reg)) {
140		dev_err(&spi->dev, "Vref regulator not specified\n");
141		return PTR_ERR(state->vref_reg);
142	}
143
144	ret = regulator_enable(state->vref_reg);
145	if (ret) {
146		dev_err(&spi->dev, "Failed to enable vref regulator: %d\n",
147				ret);
148		return ret;
149	}
150
151	ret = regulator_get_voltage(state->vref_reg);
152	if (ret < 0) {
153		dev_err(&spi->dev, "Failed to read vref regulator: %d\n",
154				ret);
155		goto error_disable_reg;
156	}
157	state->vref_mv = ret / 1000;
158
159	spi_set_drvdata(spi, indio_dev);
160	id = spi_get_device_id(spi);
161	indio_dev->dev.parent = &spi->dev;
162	indio_dev->info = &mcp4922_info;
163	indio_dev->modes = INDIO_DIRECT_MODE;
164	indio_dev->channels = mcp4922_channels[id->driver_data];
165	indio_dev->num_channels = MCP4922_NUM_CHANNELS;
166	indio_dev->name = id->name;
167
168	ret = iio_device_register(indio_dev);
169	if (ret) {
170		dev_err(&spi->dev, "Failed to register iio device: %d\n",
171				ret);
172		goto error_disable_reg;
173	}
174
175	return 0;
176
177error_disable_reg:
178	regulator_disable(state->vref_reg);
179
180	return ret;
181}
182
183static int mcp4922_remove(struct spi_device *spi)
184{
185	struct iio_dev *indio_dev = spi_get_drvdata(spi);
186	struct mcp4922_state *state;
187
188	iio_device_unregister(indio_dev);
189	state = iio_priv(indio_dev);
190	regulator_disable(state->vref_reg);
191
192	return 0;
193}
194
195static const struct spi_device_id mcp4922_id[] = {
196	{"mcp4902", ID_MCP4902},
197	{"mcp4912", ID_MCP4912},
198	{"mcp4922", ID_MCP4922},
199	{}
200};
201MODULE_DEVICE_TABLE(spi, mcp4922_id);
202
203static struct spi_driver mcp4922_driver = {
204	.driver = {
205		   .name = "mcp4922",
206		   .owner = THIS_MODULE,
207		   },
208	.probe = mcp4922_probe,
209	.remove = mcp4922_remove,
210	.id_table = mcp4922_id,
211};
212module_spi_driver(mcp4922_driver);
213
214MODULE_AUTHOR("Michael Welling <mwelling@ieee.org>");
215MODULE_DESCRIPTION("Microchip MCP4902, MCP4912, MCP4922 DAC");
216MODULE_LICENSE("GPL v2");
217