mxc6255.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * MXC6255 - MEMSIC orientation sensing accelerometer
  4 *
  5 * Copyright (c) 2015, Intel Corporation.
  6 *
  7 * IIO driver for MXC6255 (7-bit I2C slave address 0x15).
  8 */
  9
 10#include <linux/module.h>
 11#include <linux/i2c.h>
 12#include <linux/init.h>
 13#include <linux/iio/iio.h>
 14#include <linux/delay.h>
 15#include <linux/mod_devicetable.h>
 16#include <linux/regmap.h>
 17#include <linux/iio/sysfs.h>
 18
 19#define MXC6255_DRV_NAME		"mxc6255"
 20
 21#define MXC6255_REG_XOUT		0x00
 22#define MXC6255_REG_YOUT		0x01
 23#define MXC6255_REG_CHIP_ID		0x08
 24
 25#define MXC6255_CHIP_ID			0x05
 26
 27/*
 28 * MXC6255 has only one measurement range: +/- 2G.
 29 * The acceleration output is an 8-bit value.
 30 *
 31 * Scale is calculated as follows:
 32 * (2 + 2) * 9.80665 / (2^8 - 1) = 0.153829
 33 *
 34 * Scale value for +/- 2G measurement range
 35 */
 36#define MXC6255_SCALE			153829
 37
 38enum mxc6255_axis {
 39	AXIS_X,
 40	AXIS_Y,
 41};
 42
 43struct mxc6255_data {
 44	struct i2c_client *client;
 45	struct regmap *regmap;
 46};
 47
 48static int mxc6255_read_raw(struct iio_dev *indio_dev,
 49			    struct iio_chan_spec const *chan,
 50			    int *val, int *val2, long mask)
 51{
 52	struct mxc6255_data *data = iio_priv(indio_dev);
 53	unsigned int reg;
 54	int ret;
 55
 56	switch (mask) {
 57	case IIO_CHAN_INFO_RAW:
 58		ret = regmap_read(data->regmap, chan->address, &reg);
 59		if (ret < 0) {
 60			dev_err(&data->client->dev,
 61				"Error reading reg %lu\n", chan->address);
 62			return ret;
 63		}
 64
 65		*val = sign_extend32(reg, 7);
 66		return IIO_VAL_INT;
 67	case IIO_CHAN_INFO_SCALE:
 68		*val = 0;
 69		*val2 = MXC6255_SCALE;
 70		return IIO_VAL_INT_PLUS_MICRO;
 71	default:
 72		return -EINVAL;
 73	}
 74}
 75
 76static const struct iio_info mxc6255_info = {
 77	.read_raw	= mxc6255_read_raw,
 78};
 79
 80#define MXC6255_CHANNEL(_axis, reg) {				\
 81	.type = IIO_ACCEL,					\
 82	.modified = 1,						\
 83	.channel2 = IIO_MOD_##_axis,				\
 84	.address = reg,						\
 85	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
 86	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
 87}
 88
 89static const struct iio_chan_spec mxc6255_channels[] = {
 90	MXC6255_CHANNEL(X, MXC6255_REG_XOUT),
 91	MXC6255_CHANNEL(Y, MXC6255_REG_YOUT),
 92};
 93
 94static bool mxc6255_is_readable_reg(struct device *dev, unsigned int reg)
 95{
 96	switch (reg) {
 97	case MXC6255_REG_XOUT:
 98	case MXC6255_REG_YOUT:
 99	case MXC6255_REG_CHIP_ID:
100		return true;
101	default:
102		return false;
103	}
104}
105
106static const struct regmap_config mxc6255_regmap_config = {
107	.name = "mxc6255_regmap",
108
109	.reg_bits = 8,
110	.val_bits = 8,
111
112	.readable_reg = mxc6255_is_readable_reg,
113};
114
115static int mxc6255_probe(struct i2c_client *client)
116{
117	struct mxc6255_data *data;
118	struct iio_dev *indio_dev;
119	struct regmap *regmap;
120	unsigned int chip_id;
121	int ret;
122
123	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
124	if (!indio_dev)
125		return -ENOMEM;
126
127	regmap = devm_regmap_init_i2c(client, &mxc6255_regmap_config);
128	if (IS_ERR(regmap)) {
129		dev_err(&client->dev, "Error initializing regmap\n");
130		return PTR_ERR(regmap);
131	}
132
133	data = iio_priv(indio_dev);
134	i2c_set_clientdata(client, indio_dev);
135	data->client = client;
136	data->regmap = regmap;
137
138	indio_dev->name = MXC6255_DRV_NAME;
139	indio_dev->channels = mxc6255_channels;
140	indio_dev->num_channels = ARRAY_SIZE(mxc6255_channels);
141	indio_dev->modes = INDIO_DIRECT_MODE;
142	indio_dev->info = &mxc6255_info;
143
144	ret = regmap_read(data->regmap, MXC6255_REG_CHIP_ID, &chip_id);
145	if (ret < 0) {
146		dev_err(&client->dev, "Error reading chip id %d\n", ret);
147		return ret;
148	}
149
150	if ((chip_id & 0x1f) != MXC6255_CHIP_ID) {
151		dev_err(&client->dev, "Invalid chip id %x\n", chip_id);
152		return -ENODEV;
153	}
154
155	dev_dbg(&client->dev, "Chip id %x\n", chip_id);
156
157	ret = devm_iio_device_register(&client->dev, indio_dev);
158	if (ret < 0) {
159		dev_err(&client->dev, "Could not register IIO device\n");
160		return ret;
161	}
162
163	return 0;
164}
165
166static const struct acpi_device_id mxc6255_acpi_match[] = {
167	{"MXC6225",	0},
168	{"MXC6255",	0},
169	{ }
170};
171MODULE_DEVICE_TABLE(acpi, mxc6255_acpi_match);
172
173static const struct i2c_device_id mxc6255_id[] = {
174	{ "mxc6225" },
175	{ "mxc6255" },
176	{ }
177};
178MODULE_DEVICE_TABLE(i2c, mxc6255_id);
179
180static struct i2c_driver mxc6255_driver = {
181	.driver = {
182		.name = MXC6255_DRV_NAME,
183		.acpi_match_table = mxc6255_acpi_match,
184	},
185	.probe		= mxc6255_probe,
186	.id_table	= mxc6255_id,
187};
188
189module_i2c_driver(mxc6255_driver);
190
191MODULE_AUTHOR("Teodora Baluta <teodora.baluta@intel.com>");
192MODULE_DESCRIPTION("MEMSIC MXC6255 orientation sensing accelerometer driver");
193MODULE_LICENSE("GPL v2");