xref: /openbmc/linux/drivers/iio/accel/adxl345_core.c (revision 5d0e4d78)
1 /*
2  * ADXL345 3-Axis Digital Accelerometer IIO core driver
3  *
4  * Copyright (c) 2017 Eva Rachel Retuya <eraretuya@gmail.com>
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 
11 #include <linux/module.h>
12 #include <linux/regmap.h>
13 
14 #include <linux/iio/iio.h>
15 
16 #include "adxl345.h"
17 
18 #define ADXL345_REG_DEVID		0x00
19 #define ADXL345_REG_POWER_CTL		0x2D
20 #define ADXL345_REG_DATA_FORMAT		0x31
21 #define ADXL345_REG_DATAX0		0x32
22 #define ADXL345_REG_DATAY0		0x34
23 #define ADXL345_REG_DATAZ0		0x36
24 
25 #define ADXL345_POWER_CTL_MEASURE	BIT(3)
26 #define ADXL345_POWER_CTL_STANDBY	0x00
27 
28 #define ADXL345_DATA_FORMAT_FULL_RES	BIT(3) /* Up to 13-bits resolution */
29 #define ADXL345_DATA_FORMAT_2G		0
30 #define ADXL345_DATA_FORMAT_4G		1
31 #define ADXL345_DATA_FORMAT_8G		2
32 #define ADXL345_DATA_FORMAT_16G		3
33 
34 #define ADXL345_DEVID			0xE5
35 
36 /*
37  * In full-resolution mode, scale factor is maintained at ~4 mg/LSB
38  * in all g ranges.
39  *
40  * At +/- 16g with 13-bit resolution, scale is computed as:
41  * (16 + 16) * 9.81 / (2^13 - 1) = 0.0383
42  */
43 static const int adxl345_uscale = 38300;
44 
45 struct adxl345_data {
46 	struct regmap *regmap;
47 	u8 data_range;
48 };
49 
50 #define ADXL345_CHANNEL(reg, axis) {					\
51 	.type = IIO_ACCEL,						\
52 	.modified = 1,							\
53 	.channel2 = IIO_MOD_##axis,					\
54 	.address = reg,							\
55 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),			\
56 	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),		\
57 }
58 
59 static const struct iio_chan_spec adxl345_channels[] = {
60 	ADXL345_CHANNEL(ADXL345_REG_DATAX0, X),
61 	ADXL345_CHANNEL(ADXL345_REG_DATAY0, Y),
62 	ADXL345_CHANNEL(ADXL345_REG_DATAZ0, Z),
63 };
64 
65 static int adxl345_read_raw(struct iio_dev *indio_dev,
66 			    struct iio_chan_spec const *chan,
67 			    int *val, int *val2, long mask)
68 {
69 	struct adxl345_data *data = iio_priv(indio_dev);
70 	__le16 regval;
71 	int ret;
72 
73 	switch (mask) {
74 	case IIO_CHAN_INFO_RAW:
75 		/*
76 		 * Data is stored in adjacent registers:
77 		 * ADXL345_REG_DATA(X0/Y0/Z0) contain the least significant byte
78 		 * and ADXL345_REG_DATA(X0/Y0/Z0) + 1 the most significant byte
79 		 */
80 		ret = regmap_bulk_read(data->regmap, chan->address, &regval,
81 				       sizeof(regval));
82 		if (ret < 0)
83 			return ret;
84 
85 		*val = sign_extend32(le16_to_cpu(regval), 12);
86 		return IIO_VAL_INT;
87 	case IIO_CHAN_INFO_SCALE:
88 		*val = 0;
89 		*val2 = adxl345_uscale;
90 
91 		return IIO_VAL_INT_PLUS_MICRO;
92 	}
93 
94 	return -EINVAL;
95 }
96 
97 static const struct iio_info adxl345_info = {
98 	.driver_module	= THIS_MODULE,
99 	.read_raw	= adxl345_read_raw,
100 };
101 
102 int adxl345_core_probe(struct device *dev, struct regmap *regmap,
103 		       const char *name)
104 {
105 	struct adxl345_data *data;
106 	struct iio_dev *indio_dev;
107 	u32 regval;
108 	int ret;
109 
110 	ret = regmap_read(regmap, ADXL345_REG_DEVID, &regval);
111 	if (ret < 0) {
112 		dev_err(dev, "Error reading device ID: %d\n", ret);
113 		return ret;
114 	}
115 
116 	if (regval != ADXL345_DEVID) {
117 		dev_err(dev, "Invalid device ID: %x, expected %x\n",
118 			regval, ADXL345_DEVID);
119 		return -ENODEV;
120 	}
121 
122 	indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
123 	if (!indio_dev)
124 		return -ENOMEM;
125 
126 	data = iio_priv(indio_dev);
127 	dev_set_drvdata(dev, indio_dev);
128 	data->regmap = regmap;
129 	/* Enable full-resolution mode */
130 	data->data_range = ADXL345_DATA_FORMAT_FULL_RES;
131 
132 	ret = regmap_write(data->regmap, ADXL345_REG_DATA_FORMAT,
133 			   data->data_range);
134 	if (ret < 0) {
135 		dev_err(dev, "Failed to set data range: %d\n", ret);
136 		return ret;
137 	}
138 
139 	indio_dev->dev.parent = dev;
140 	indio_dev->name = name;
141 	indio_dev->info = &adxl345_info;
142 	indio_dev->modes = INDIO_DIRECT_MODE;
143 	indio_dev->channels = adxl345_channels;
144 	indio_dev->num_channels = ARRAY_SIZE(adxl345_channels);
145 
146 	/* Enable measurement mode */
147 	ret = regmap_write(data->regmap, ADXL345_REG_POWER_CTL,
148 			   ADXL345_POWER_CTL_MEASURE);
149 	if (ret < 0) {
150 		dev_err(dev, "Failed to enable measurement mode: %d\n", ret);
151 		return ret;
152 	}
153 
154 	ret = iio_device_register(indio_dev);
155 	if (ret < 0) {
156 		dev_err(dev, "iio_device_register failed: %d\n", ret);
157 		regmap_write(data->regmap, ADXL345_REG_POWER_CTL,
158 			     ADXL345_POWER_CTL_STANDBY);
159 	}
160 
161 	return ret;
162 }
163 EXPORT_SYMBOL_GPL(adxl345_core_probe);
164 
165 int adxl345_core_remove(struct device *dev)
166 {
167 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
168 	struct adxl345_data *data = iio_priv(indio_dev);
169 
170 	iio_device_unregister(indio_dev);
171 
172 	return regmap_write(data->regmap, ADXL345_REG_POWER_CTL,
173 			    ADXL345_POWER_CTL_STANDBY);
174 }
175 EXPORT_SYMBOL_GPL(adxl345_core_remove);
176 
177 MODULE_AUTHOR("Eva Rachel Retuya <eraretuya@gmail.com>");
178 MODULE_DESCRIPTION("ADXL345 3-Axis Digital Accelerometer core driver");
179 MODULE_LICENSE("GPL v2");
180