mcp4922.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * mcp4922.c
  4 *
  5 * Driver for Microchip Digital to Analog Converters.
  6 * Supports MCP4902, MCP4912, and MCP4922.
  7 *
  8 * Copyright (c) 2014 EMAC Inc.
  9 */
 10
 11#include <linux/module.h>
 12#include <linux/init.h>
 13#include <linux/spi/spi.h>
 14#include <linux/iio/iio.h>
 15#include <linux/iio/sysfs.h>
 16#include <linux/regulator/consumer.h>
 17#include <linux/bitops.h>
 18
 19#define MCP4922_NUM_CHANNELS	2
 20#define MCP4921_NUM_CHANNELS	1
 21
 22enum mcp4922_supported_device_ids {
 23	ID_MCP4902,
 24	ID_MCP4912,
 25	ID_MCP4921,
 26	ID_MCP4922,
 27};
 28
 29struct mcp4922_state {
 30	struct spi_device *spi;
 31	unsigned int value[MCP4922_NUM_CHANNELS];
 32	unsigned int vref_mv;
 33	u8 mosi[2] __aligned(IIO_DMA_MINALIGN);
 34};
 35
 36#define MCP4922_CHAN(chan, bits) {			\
 37	.type = IIO_VOLTAGE,				\
 38	.output = 1,					\
 39	.indexed = 1,					\
 40	.channel = chan,				\
 41	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
 42	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
 43	.scan_type = {					\
 44		.sign = 'u',				\
 45		.realbits = (bits),			\
 46		.storagebits = 16,			\
 47		.shift = 12 - (bits),			\
 48	},						\
 49}
 50
 51static int mcp4922_spi_write(struct mcp4922_state *state, u8 addr, u32 val)
 52{
 53	state->mosi[1] = val & 0xff;
 54	state->mosi[0] = (addr == 0) ? 0x00 : 0x80;
 55	state->mosi[0] |= 0x30 | ((val >> 8) & 0x0f);
 56
 57	return spi_write(state->spi, state->mosi, 2);
 58}
 59
 60static int mcp4922_read_raw(struct iio_dev *indio_dev,
 61		struct iio_chan_spec const *chan,
 62		int *val,
 63		int *val2,
 64		long mask)
 65{
 66	struct mcp4922_state *state = iio_priv(indio_dev);
 67
 68	switch (mask) {
 69	case IIO_CHAN_INFO_RAW:
 70		*val = state->value[chan->channel];
 71		return IIO_VAL_INT;
 72	case IIO_CHAN_INFO_SCALE:
 73		*val = state->vref_mv;
 74		*val2 = chan->scan_type.realbits;
 75		return IIO_VAL_FRACTIONAL_LOG2;
 76	default:
 77		return -EINVAL;
 78	}
 79}
 80
 81static int mcp4922_write_raw(struct iio_dev *indio_dev,
 82		struct iio_chan_spec const *chan,
 83		int val,
 84		int val2,
 85		long mask)
 86{
 87	struct mcp4922_state *state = iio_priv(indio_dev);
 88	int ret;
 89
 90	if (val2 != 0)
 91		return -EINVAL;
 92
 93	switch (mask) {
 94	case IIO_CHAN_INFO_RAW:
 95		if (val < 0 || val > GENMASK(chan->scan_type.realbits - 1, 0))
 96			return -EINVAL;
 97		val <<= chan->scan_type.shift;
 98
 99		ret = mcp4922_spi_write(state, chan->channel, val);
100		if (!ret)
101			state->value[chan->channel] = val;
102		return ret;
103
104	default:
105		return -EINVAL;
106	}
107}
108
109static const struct iio_chan_spec mcp4922_channels[4][MCP4922_NUM_CHANNELS] = {
110	[ID_MCP4902] = { MCP4922_CHAN(0, 8),	MCP4922_CHAN(1, 8) },
111	[ID_MCP4912] = { MCP4922_CHAN(0, 10),	MCP4922_CHAN(1, 10) },
112	[ID_MCP4921] = { MCP4922_CHAN(0, 12),	{} },
113	[ID_MCP4922] = { MCP4922_CHAN(0, 12),	MCP4922_CHAN(1, 12) },
114};
115
116static const struct iio_info mcp4922_info = {
117	.read_raw = &mcp4922_read_raw,
118	.write_raw = &mcp4922_write_raw,
119};
120
121static int mcp4922_probe(struct spi_device *spi)
122{
123	struct iio_dev *indio_dev;
124	struct mcp4922_state *state;
125	const struct spi_device_id *id;
126	int ret;
127
128	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state));
129	if (indio_dev == NULL)
130		return -ENOMEM;
131
132	state = iio_priv(indio_dev);
133	state->spi = spi;
134
135	ret = devm_regulator_get_enable_read_voltage(&spi->dev, "vref");
136	if (ret < 0)
137		return dev_err_probe(&spi->dev, ret, "Failed to get vref voltage\n");
138
139	state->vref_mv = ret / 1000;
140
141	id = spi_get_device_id(spi);
142	indio_dev->info = &mcp4922_info;
143	indio_dev->modes = INDIO_DIRECT_MODE;
144	indio_dev->channels = mcp4922_channels[id->driver_data];
145	if (id->driver_data == ID_MCP4921)
146		indio_dev->num_channels = MCP4921_NUM_CHANNELS;
147	else
148		indio_dev->num_channels = MCP4922_NUM_CHANNELS;
149	indio_dev->name = id->name;
150
151	ret = devm_iio_device_register(&spi->dev, indio_dev);
152	if (ret)
153		return dev_err_probe(&spi->dev, ret, "Failed to register iio device\n");
154
155	return 0;
156}
157
158
159static const struct spi_device_id mcp4922_id[] = {
160	{"mcp4902", ID_MCP4902},
161	{"mcp4912", ID_MCP4912},
162	{"mcp4921", ID_MCP4921},
163	{"mcp4922", ID_MCP4922},
164	{ }
165};
166MODULE_DEVICE_TABLE(spi, mcp4922_id);
167
168static struct spi_driver mcp4922_driver = {
169	.driver = {
170		   .name = "mcp4922",
171		   },
172	.probe = mcp4922_probe,
173	.id_table = mcp4922_id,
174};
175module_spi_driver(mcp4922_driver);
176
177MODULE_AUTHOR("Michael Welling <mwelling@ieee.org>");
178MODULE_DESCRIPTION("Microchip MCP4902, MCP4912, MCP4922 DAC");
179MODULE_LICENSE("GPL v2");