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/acpi.h>
16#include <linux/regmap.h>
17#include <linux/iio/sysfs.h>
18
19#define MXC6255_DRV_NAME		"mxc6255"
20#define MXC6255_REGMAP_NAME		"mxc6255_regmap"
21
22#define MXC6255_REG_XOUT		0x00
23#define MXC6255_REG_YOUT		0x01
24#define MXC6255_REG_CHIP_ID		0x08
25
26#define MXC6255_CHIP_ID			0x05
27
28/*
29 * MXC6255 has only one measurement range: +/- 2G.
30 * The acceleration output is an 8-bit value.
31 *
32 * Scale is calculated as follows:
33 * (2 + 2) * 9.80665 / (2^8 - 1) = 0.153829
34 *
35 * Scale value for +/- 2G measurement range
36 */
37#define MXC6255_SCALE			153829
38
39enum mxc6255_axis {
40	AXIS_X,
41	AXIS_Y,
42};
43
44struct mxc6255_data {
45	struct i2c_client *client;
46	struct regmap *regmap;
47};
48
49static int mxc6255_read_raw(struct iio_dev *indio_dev,
50			    struct iio_chan_spec const *chan,
51			    int *val, int *val2, long mask)
52{
53	struct mxc6255_data *data = iio_priv(indio_dev);
54	unsigned int reg;
55	int ret;
56
57	switch (mask) {
58	case IIO_CHAN_INFO_RAW:
59		ret = regmap_read(data->regmap, chan->address, &reg);
60		if (ret < 0) {
61			dev_err(&data->client->dev,
62				"Error reading reg %lu\n", chan->address);
63			return ret;
64		}
65
66		*val = sign_extend32(reg, 7);
67		return IIO_VAL_INT;
68	case IIO_CHAN_INFO_SCALE:
69		*val = 0;
70		*val2 = MXC6255_SCALE;
71		return IIO_VAL_INT_PLUS_MICRO;
72	default:
73		return -EINVAL;
74	}
75}
76
77static const struct iio_info mxc6255_info = {
78	.read_raw	= mxc6255_read_raw,
79};
80
81#define MXC6255_CHANNEL(_axis, reg) {				\
82	.type = IIO_ACCEL,					\
83	.modified = 1,						\
84	.channel2 = IIO_MOD_##_axis,				\
85	.address = reg,						\
86	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
87	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
88}
89
90static const struct iio_chan_spec mxc6255_channels[] = {
91	MXC6255_CHANNEL(X, MXC6255_REG_XOUT),
92	MXC6255_CHANNEL(Y, MXC6255_REG_YOUT),
93};
94
95static bool mxc6255_is_readable_reg(struct device *dev, unsigned int reg)
96{
97	switch (reg) {
98	case MXC6255_REG_XOUT:
99	case MXC6255_REG_YOUT:
100	case MXC6255_REG_CHIP_ID:
101		return true;
102	default:
103		return false;
104	}
105}
106
107static const struct regmap_config mxc6255_regmap_config = {
108	.name = MXC6255_REGMAP_NAME,
109
110	.reg_bits = 8,
111	.val_bits = 8,
112
113	.readable_reg = mxc6255_is_readable_reg,
114};
115
116static int mxc6255_probe(struct i2c_client *client,
117			 const struct i2c_device_id *id)
118{
119	struct mxc6255_data *data;
120	struct iio_dev *indio_dev;
121	struct regmap *regmap;
122	unsigned int chip_id;
123	int ret;
124
125	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
126	if (!indio_dev)
127		return -ENOMEM;
128
129	regmap = devm_regmap_init_i2c(client, &mxc6255_regmap_config);
130	if (IS_ERR(regmap)) {
131		dev_err(&client->dev, "Error initializing regmap\n");
132		return PTR_ERR(regmap);
133	}
134
135	data = iio_priv(indio_dev);
136	i2c_set_clientdata(client, indio_dev);
137	data->client = client;
138	data->regmap = regmap;
139
140	indio_dev->name = MXC6255_DRV_NAME;
141	indio_dev->channels = mxc6255_channels;
142	indio_dev->num_channels = ARRAY_SIZE(mxc6255_channels);
143	indio_dev->modes = INDIO_DIRECT_MODE;
144	indio_dev->info = &mxc6255_info;
145
146	ret = regmap_read(data->regmap, MXC6255_REG_CHIP_ID, &chip_id);
147	if (ret < 0) {
148		dev_err(&client->dev, "Error reading chip id %d\n", ret);
149		return ret;
150	}
151
152	if ((chip_id & 0x1f) != MXC6255_CHIP_ID) {
153		dev_err(&client->dev, "Invalid chip id %x\n", chip_id);
154		return -ENODEV;
155	}
156
157	dev_dbg(&client->dev, "Chip id %x\n", chip_id);
158
159	ret = devm_iio_device_register(&client->dev, indio_dev);
160	if (ret < 0) {
161		dev_err(&client->dev, "Could not register IIO device\n");
162		return ret;
163	}
164
165	return 0;
166}
167
168static const struct acpi_device_id mxc6255_acpi_match[] = {
169	{"MXC6225",	0},
170	{"MXC6255",	0},
171	{ }
172};
173MODULE_DEVICE_TABLE(acpi, mxc6255_acpi_match);
174
175static const struct i2c_device_id mxc6255_id[] = {
176	{"mxc6225",	0},
177	{"mxc6255",	0},
178	{ }
179};
180MODULE_DEVICE_TABLE(i2c, mxc6255_id);
181
182static struct i2c_driver mxc6255_driver = {
183	.driver = {
184		.name = MXC6255_DRV_NAME,
185		.acpi_match_table = ACPI_PTR(mxc6255_acpi_match),
186	},
187	.probe		= mxc6255_probe,
188	.id_table	= mxc6255_id,
189};
190
191module_i2c_driver(mxc6255_driver);
192
193MODULE_AUTHOR("Teodora Baluta <teodora.baluta@intel.com>");
194MODULE_DESCRIPTION("MEMSIC MXC6255 orientation sensing accelerometer driver");
195MODULE_LICENSE("GPL v2");
196