tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
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, ®);
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->dev.parent = &client->dev;
142 indio_dev->channels = mxc6255_channels;
143 indio_dev->num_channels = ARRAY_SIZE(mxc6255_channels);
144 indio_dev->modes = INDIO_DIRECT_MODE;
145 indio_dev->info = &mxc6255_info;
146
147 ret = regmap_read(data->regmap, MXC6255_REG_CHIP_ID, &chip_id);
148 if (ret < 0) {
149 dev_err(&client->dev, "Error reading chip id %d\n", ret);
150 return ret;
151 }
152
153 if ((chip_id & 0x1f) != MXC6255_CHIP_ID) {
154 dev_err(&client->dev, "Invalid chip id %x\n", chip_id);
155 return -ENODEV;
156 }
157
158 dev_dbg(&client->dev, "Chip id %x\n", chip_id);
159
160 ret = devm_iio_device_register(&client->dev, indio_dev);
161 if (ret < 0) {
162 dev_err(&client->dev, "Could not register IIO device\n");
163 return ret;
164 }
165
166 return 0;
167}
168
169static const struct acpi_device_id mxc6255_acpi_match[] = {
170 {"MXC6225", 0},
171 {"MXC6255", 0},
172 { }
173};
174MODULE_DEVICE_TABLE(acpi, mxc6255_acpi_match);
175
176static const struct i2c_device_id mxc6255_id[] = {
177 {"mxc6225", 0},
178 {"mxc6255", 0},
179 { }
180};
181MODULE_DEVICE_TABLE(i2c, mxc6255_id);
182
183static struct i2c_driver mxc6255_driver = {
184 .driver = {
185 .name = MXC6255_DRV_NAME,
186 .acpi_match_table = ACPI_PTR(mxc6255_acpi_match),
187 },
188 .probe = mxc6255_probe,
189 .id_table = mxc6255_id,
190};
191
192module_i2c_driver(mxc6255_driver);
193
194MODULE_AUTHOR("Teodora Baluta <teodora.baluta@intel.com>");
195MODULE_DESCRIPTION("MEMSIC MXC6255 orientation sensing accelerometer driver");
196MODULE_LICENSE("GPL v2");