dmard09.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * IIO driver for the 3-axis accelerometer Domintech DMARD09.
  4 *
  5 * Copyright (c) 2016, Jelle van der Waa <jelle@vdwaa.nl>
  6 */
  7
  8#include <linux/unaligned.h>
  9#include <linux/module.h>
 10#include <linux/i2c.h>
 11#include <linux/iio/iio.h>
 12
 13#define DMARD09_DRV_NAME	"dmard09"
 14
 15#define DMARD09_REG_CHIPID      0x18
 16#define DMARD09_REG_STAT	0x0A
 17#define DMARD09_REG_X		0x0C
 18#define DMARD09_REG_Y		0x0E
 19#define DMARD09_REG_Z		0x10
 20#define DMARD09_CHIPID		0x95
 21
 22#define DMARD09_BUF_LEN 8
 23#define DMARD09_AXIS_X 0
 24#define DMARD09_AXIS_Y 1
 25#define DMARD09_AXIS_Z 2
 26#define DMARD09_AXIS_X_OFFSET ((DMARD09_AXIS_X + 1) * 2)
 27#define DMARD09_AXIS_Y_OFFSET ((DMARD09_AXIS_Y + 1) * 2)
 28#define DMARD09_AXIS_Z_OFFSET ((DMARD09_AXIS_Z + 1) * 2)
 29
 30struct dmard09_data {
 31	struct i2c_client *client;
 32};
 33
 34#define DMARD09_CHANNEL(_axis, offset) {			\
 35	.type = IIO_ACCEL,					\
 36	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
 37	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
 38	.modified = 1,						\
 39	.address = offset,					\
 40	.channel2 = IIO_MOD_##_axis,				\
 41}
 42
 43static const struct iio_chan_spec dmard09_channels[] = {
 44	DMARD09_CHANNEL(X, DMARD09_AXIS_X_OFFSET),
 45	DMARD09_CHANNEL(Y, DMARD09_AXIS_Y_OFFSET),
 46	DMARD09_CHANNEL(Z, DMARD09_AXIS_Z_OFFSET),
 47};
 48
 49static int dmard09_read_raw(struct iio_dev *indio_dev,
 50			    struct iio_chan_spec const *chan,
 51			    int *val, int *val2, long mask)
 52{
 53	struct dmard09_data *data = iio_priv(indio_dev);
 54	u8 buf[DMARD09_BUF_LEN];
 55	int ret;
 56	s16 accel;
 57
 58	switch (mask) {
 59	case IIO_CHAN_INFO_RAW:
 60		/*
 61		 * Read from the DMAR09_REG_STAT register, since the chip
 62		 * caches reads from the individual X, Y, Z registers.
 63		 */
 64		ret = i2c_smbus_read_i2c_block_data(data->client,
 65						    DMARD09_REG_STAT,
 66						    DMARD09_BUF_LEN, buf);
 67		if (ret < 0) {
 68			dev_err(&data->client->dev, "Error reading reg %d\n",
 69				DMARD09_REG_STAT);
 70			return ret;
 71		}
 72
 73		accel = get_unaligned_le16(&buf[chan->address]);
 74
 75		/* Remove lower 3 bits and sign extend */
 76		accel <<= 4;
 77		accel >>= 7;
 78
 79		*val = accel;
 80
 81		return IIO_VAL_INT;
 82	default:
 83		return -EINVAL;
 84	}
 85}
 86
 87static const struct iio_info dmard09_info = {
 88	.read_raw	= dmard09_read_raw,
 89};
 90
 91static int dmard09_probe(struct i2c_client *client)
 92{
 93	int ret;
 94	struct iio_dev *indio_dev;
 95	struct dmard09_data *data;
 96
 97	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
 98	if (!indio_dev)
 99		return -ENOMEM;
100
101	data = iio_priv(indio_dev);
102	data->client = client;
103
104	ret = i2c_smbus_read_byte_data(data->client, DMARD09_REG_CHIPID);
105	if (ret < 0) {
106		dev_err(&client->dev, "Error reading chip id %d\n", ret);
107		return ret;
108	}
109
110	if (ret != DMARD09_CHIPID) {
111		dev_err(&client->dev, "Invalid chip id %d\n", ret);
112		return -ENODEV;
113	}
114
115	i2c_set_clientdata(client, indio_dev);
116	indio_dev->name = DMARD09_DRV_NAME;
117	indio_dev->modes = INDIO_DIRECT_MODE;
118	indio_dev->channels = dmard09_channels;
119	indio_dev->num_channels = ARRAY_SIZE(dmard09_channels);
120	indio_dev->info = &dmard09_info;
121
122	return devm_iio_device_register(&client->dev, indio_dev);
123}
124
125static const struct i2c_device_id dmard09_id[] = {
126	{ "dmard09" },
127	{ }
128};
129
130MODULE_DEVICE_TABLE(i2c, dmard09_id);
131
132static struct i2c_driver dmard09_driver = {
133	.driver = {
134		.name = DMARD09_DRV_NAME
135	},
136	.probe = dmard09_probe,
137	.id_table = dmard09_id,
138};
139
140module_i2c_driver(dmard09_driver);
141
142MODULE_AUTHOR("Jelle van der Waa <jelle@vdwaa.nl>");
143MODULE_DESCRIPTION("DMARD09 3-axis accelerometer driver");
144MODULE_LICENSE("GPL");