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3e5580c4 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
1d3eacbf ML |
2 | /* |
3 | * Driver for Linear Technology LTC2471 and LTC2473 voltage monitors | |
4 | * The LTC2473 is identical to the 2471, but reports a differential signal. | |
5 | * | |
6 | * Copyright (C) 2017 Topic Embedded Products | |
7 | * Author: Mike Looijmans <mike.looijmans@topic.nl> | |
1d3eacbf ML |
8 | */ |
9 | ||
10 | #include <linux/err.h> | |
11 | #include <linux/i2c.h> | |
12 | #include <linux/kernel.h> | |
13 | #include <linux/module.h> | |
14 | #include <linux/iio/iio.h> | |
15 | #include <linux/iio/sysfs.h> | |
16 | ||
17 | enum ltc2471_chips { | |
18 | ltc2471, | |
19 | ltc2473, | |
20 | }; | |
21 | ||
22 | struct ltc2471_data { | |
23 | struct i2c_client *client; | |
24 | }; | |
25 | ||
26 | /* Reference voltage is 1.25V */ | |
27 | #define LTC2471_VREF 1250 | |
28 | ||
29 | /* Read two bytes from the I2C bus to obtain the ADC result */ | |
30 | static int ltc2471_get_value(struct i2c_client *client) | |
31 | { | |
32 | int ret; | |
33 | __be16 buf; | |
34 | ||
35 | ret = i2c_master_recv(client, (char *)&buf, sizeof(buf)); | |
36 | if (ret < 0) | |
37 | return ret; | |
38 | if (ret != sizeof(buf)) | |
39 | return -EIO; | |
40 | ||
41 | /* MSB first */ | |
42 | return be16_to_cpu(buf); | |
43 | } | |
44 | ||
45 | static int ltc2471_read_raw(struct iio_dev *indio_dev, | |
46 | struct iio_chan_spec const *chan, | |
47 | int *val, int *val2, long info) | |
48 | { | |
49 | struct ltc2471_data *data = iio_priv(indio_dev); | |
50 | int ret; | |
51 | ||
52 | switch (info) { | |
53 | case IIO_CHAN_INFO_RAW: | |
54 | ret = ltc2471_get_value(data->client); | |
55 | if (ret < 0) | |
56 | return ret; | |
57 | *val = ret; | |
58 | return IIO_VAL_INT; | |
59 | ||
60 | case IIO_CHAN_INFO_SCALE: | |
61 | if (chan->differential) | |
62 | /* Output ranges from -VREF to +VREF */ | |
63 | *val = 2 * LTC2471_VREF; | |
64 | else | |
65 | /* Output ranges from 0 to VREF */ | |
66 | *val = LTC2471_VREF; | |
67 | *val2 = 16; /* 16 data bits */ | |
68 | return IIO_VAL_FRACTIONAL_LOG2; | |
69 | ||
70 | case IIO_CHAN_INFO_OFFSET: | |
71 | /* Only differential chip has this property */ | |
72 | *val = -LTC2471_VREF; | |
73 | return IIO_VAL_INT; | |
74 | ||
75 | default: | |
76 | return -EINVAL; | |
77 | } | |
78 | } | |
79 | ||
80 | static const struct iio_chan_spec ltc2471_channel[] = { | |
81 | { | |
82 | .type = IIO_VOLTAGE, | |
83 | .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), | |
84 | .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), | |
85 | }, | |
86 | }; | |
87 | ||
88 | static const struct iio_chan_spec ltc2473_channel[] = { | |
89 | { | |
90 | .type = IIO_VOLTAGE, | |
91 | .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), | |
92 | .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | | |
93 | BIT(IIO_CHAN_INFO_OFFSET), | |
94 | .differential = 1, | |
95 | }, | |
96 | }; | |
97 | ||
98 | static const struct iio_info ltc2471_info = { | |
99 | .read_raw = ltc2471_read_raw, | |
1d3eacbf ML |
100 | }; |
101 | ||
7b8c4fa4 | 102 | static int ltc2471_i2c_probe(struct i2c_client *client) |
1d3eacbf | 103 | { |
7b8c4fa4 | 104 | const struct i2c_device_id *id = i2c_client_get_device_id(client); |
1d3eacbf ML |
105 | struct iio_dev *indio_dev; |
106 | struct ltc2471_data *data; | |
107 | int ret; | |
108 | ||
109 | if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) | |
110 | return -EOPNOTSUPP; | |
111 | ||
112 | indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); | |
113 | if (!indio_dev) | |
114 | return -ENOMEM; | |
115 | ||
116 | data = iio_priv(indio_dev); | |
117 | data->client = client; | |
118 | ||
1d3eacbf ML |
119 | indio_dev->name = id->name; |
120 | indio_dev->info = <c2471_info; | |
121 | indio_dev->modes = INDIO_DIRECT_MODE; | |
122 | if (id->driver_data == ltc2473) | |
123 | indio_dev->channels = ltc2473_channel; | |
124 | else | |
125 | indio_dev->channels = ltc2471_channel; | |
126 | indio_dev->num_channels = 1; | |
127 | ||
128 | /* Trigger once to start conversion and check if chip is there */ | |
129 | ret = ltc2471_get_value(client); | |
130 | if (ret < 0) { | |
131 | dev_err(&client->dev, "Cannot read from device.\n"); | |
132 | return ret; | |
133 | } | |
134 | ||
135 | return devm_iio_device_register(&client->dev, indio_dev); | |
136 | } | |
137 | ||
138 | static const struct i2c_device_id ltc2471_i2c_id[] = { | |
139 | { "ltc2471", ltc2471 }, | |
140 | { "ltc2473", ltc2473 }, | |
141 | {} | |
142 | }; | |
143 | MODULE_DEVICE_TABLE(i2c, ltc2471_i2c_id); | |
144 | ||
145 | static struct i2c_driver ltc2471_i2c_driver = { | |
146 | .driver = { | |
147 | .name = "ltc2471", | |
148 | }, | |
7b8c4fa4 | 149 | .probe_new = ltc2471_i2c_probe, |
1d3eacbf ML |
150 | .id_table = ltc2471_i2c_id, |
151 | }; | |
152 | ||
153 | module_i2c_driver(ltc2471_i2c_driver); | |
154 | ||
155 | MODULE_DESCRIPTION("LTC2471/LTC2473 ADC driver"); | |
156 | MODULE_AUTHOR("Topic Embedded Products"); | |
157 | MODULE_LICENSE("GPL v2"); |