tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * MXC6255 - MEMSIC orientation sensing accelerometer
3 *
4 * Copyright (c) 2015, Intel Corporation.
5 *
6 * This file is subject to the terms and conditions of version 2 of
7 * the GNU General Public License. See the file COPYING in the main
8 * directory of this archive for more details.
9 *
10 * IIO driver for MXC6255 (7-bit I2C slave address 0x15).
11 */
12
13#include <linux/module.h>
14#include <linux/i2c.h>
15#include <linux/init.h>
16#include <linux/iio/iio.h>
17#include <linux/delay.h>
18#include <linux/acpi.h>
19#include <linux/regmap.h>
20#include <linux/iio/sysfs.h>
21
22#define MXC6255_DRV_NAME "mxc6255"
23#define MXC6255_REGMAP_NAME "mxc6255_regmap"
24
25#define MXC6255_REG_XOUT 0x00
26#define MXC6255_REG_YOUT 0x01
27#define MXC6255_REG_CHIP_ID 0x08
28
29#define MXC6255_CHIP_ID 0x05
30
31/*
32 * MXC6255 has only one measurement range: +/- 2G.
33 * The acceleration output is an 8-bit value.
34 *
35 * Scale is calculated as follows:
36 * (2 + 2) * 9.80665 / (2^8 - 1) = 0.153829
37 *
38 * Scale value for +/- 2G measurement range
39 */
40#define MXC6255_SCALE 153829
41
42enum mxc6255_axis {
43 AXIS_X,
44 AXIS_Y,
45};
46
47struct mxc6255_data {
48 struct i2c_client *client;
49 struct regmap *regmap;
50};
51
52static int mxc6255_read_raw(struct iio_dev *indio_dev,
53 struct iio_chan_spec const *chan,
54 int *val, int *val2, long mask)
55{
56 struct mxc6255_data *data = iio_priv(indio_dev);
57 unsigned int reg;
58 int ret;
59
60 switch (mask) {
61 case IIO_CHAN_INFO_RAW:
62 ret = regmap_read(data->regmap, chan->address, ®);
63 if (ret < 0) {
64 dev_err(&data->client->dev,
65 "Error reading reg %lu\n", chan->address);
66 return ret;
67 }
68
69 *val = sign_extend32(reg, 7);
70 return IIO_VAL_INT;
71 case IIO_CHAN_INFO_SCALE:
72 *val = 0;
73 *val2 = MXC6255_SCALE;
74 return IIO_VAL_INT_PLUS_MICRO;
75 default:
76 return -EINVAL;
77 }
78}
79
80static const struct iio_info mxc6255_info = {
81 .read_raw = mxc6255_read_raw,
82};
83
84#define MXC6255_CHANNEL(_axis, reg) { \
85 .type = IIO_ACCEL, \
86 .modified = 1, \
87 .channel2 = IIO_MOD_##_axis, \
88 .address = reg, \
89 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
90 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
91}
92
93static const struct iio_chan_spec mxc6255_channels[] = {
94 MXC6255_CHANNEL(X, MXC6255_REG_XOUT),
95 MXC6255_CHANNEL(Y, MXC6255_REG_YOUT),
96};
97
98static bool mxc6255_is_readable_reg(struct device *dev, unsigned int reg)
99{
100 switch (reg) {
101 case MXC6255_REG_XOUT:
102 case MXC6255_REG_YOUT:
103 case MXC6255_REG_CHIP_ID:
104 return true;
105 default:
106 return false;
107 }
108}
109
110static const struct regmap_config mxc6255_regmap_config = {
111 .name = MXC6255_REGMAP_NAME,
112
113 .reg_bits = 8,
114 .val_bits = 8,
115
116 .readable_reg = mxc6255_is_readable_reg,
117};
118
119static int mxc6255_probe(struct i2c_client *client,
120 const struct i2c_device_id *id)
121{
122 struct mxc6255_data *data;
123 struct iio_dev *indio_dev;
124 struct regmap *regmap;
125 unsigned int chip_id;
126 int ret;
127
128 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
129 if (!indio_dev)
130 return -ENOMEM;
131
132 regmap = devm_regmap_init_i2c(client, &mxc6255_regmap_config);
133 if (IS_ERR(regmap)) {
134 dev_err(&client->dev, "Error initializing regmap\n");
135 return PTR_ERR(regmap);
136 }
137
138 data = iio_priv(indio_dev);
139 i2c_set_clientdata(client, indio_dev);
140 data->client = client;
141 data->regmap = regmap;
142
143 indio_dev->name = MXC6255_DRV_NAME;
144 indio_dev->dev.parent = &client->dev;
145 indio_dev->channels = mxc6255_channels;
146 indio_dev->num_channels = ARRAY_SIZE(mxc6255_channels);
147 indio_dev->modes = INDIO_DIRECT_MODE;
148 indio_dev->info = &mxc6255_info;
149
150 ret = regmap_read(data->regmap, MXC6255_REG_CHIP_ID, &chip_id);
151 if (ret < 0) {
152 dev_err(&client->dev, "Error reading chip id %d\n", ret);
153 return ret;
154 }
155
156 if ((chip_id & 0x1f) != MXC6255_CHIP_ID) {
157 dev_err(&client->dev, "Invalid chip id %x\n", chip_id);
158 return -ENODEV;
159 }
160
161 dev_dbg(&client->dev, "Chip id %x\n", chip_id);
162
163 ret = devm_iio_device_register(&client->dev, indio_dev);
164 if (ret < 0) {
165 dev_err(&client->dev, "Could not register IIO device\n");
166 return ret;
167 }
168
169 return 0;
170}
171
172static const struct acpi_device_id mxc6255_acpi_match[] = {
173 {"MXC6225", 0},
174 {"MXC6255", 0},
175 { }
176};
177MODULE_DEVICE_TABLE(acpi, mxc6255_acpi_match);
178
179static const struct i2c_device_id mxc6255_id[] = {
180 {"mxc6225", 0},
181 {"mxc6255", 0},
182 { }
183};
184MODULE_DEVICE_TABLE(i2c, mxc6255_id);
185
186static struct i2c_driver mxc6255_driver = {
187 .driver = {
188 .name = MXC6255_DRV_NAME,
189 .acpi_match_table = ACPI_PTR(mxc6255_acpi_match),
190 },
191 .probe = mxc6255_probe,
192 .id_table = mxc6255_id,
193};
194
195module_i2c_driver(mxc6255_driver);
196
197MODULE_AUTHOR("Teodora Baluta <teodora.baluta@intel.com>");
198MODULE_DESCRIPTION("MEMSIC MXC6255 orientation sensing accelerometer driver");
199MODULE_LICENSE("GPL v2");