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d2912cb1 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
8c9e7b1b AS |
2 | /* |
3 | * ltc2485.c - Driver for Linear Technology LTC2485 ADC | |
4 | * | |
5 | * Copyright (C) 2016 Alison Schofield <amsfield22@gmail.com> | |
6 | * | |
8c9e7b1b AS |
7 | * Datasheet: http://cds.linear.com/docs/en/datasheet/2485fd.pdf |
8 | */ | |
9 | ||
10 | #include <linux/delay.h> | |
11 | #include <linux/i2c.h> | |
12 | #include <linux/module.h> | |
13 | ||
14 | #include <linux/iio/iio.h> | |
15 | #include <linux/iio/sysfs.h> | |
16 | ||
17 | /* Power-on configuration: rejects both 50/60Hz, operates at 1x speed */ | |
18 | #define LTC2485_CONFIG_DEFAULT 0 | |
19 | ||
20 | struct ltc2485_data { | |
21 | struct i2c_client *client; | |
22 | ktime_t time_prev; /* last conversion */ | |
23 | }; | |
24 | ||
25 | static void ltc2485_wait_conv(struct ltc2485_data *data) | |
26 | { | |
27 | const unsigned int conv_time = 147; /* conversion time ms */ | |
28 | unsigned int time_elapsed; | |
29 | ||
30 | /* delay if conversion time not passed since last read or write */ | |
31 | time_elapsed = ktime_ms_delta(ktime_get(), data->time_prev); | |
32 | ||
33 | if (time_elapsed < conv_time) | |
34 | msleep(conv_time - time_elapsed); | |
35 | } | |
36 | ||
37 | static int ltc2485_read(struct ltc2485_data *data, int *val) | |
38 | { | |
39 | struct i2c_client *client = data->client; | |
40 | __be32 buf = 0; | |
41 | int ret; | |
42 | ||
43 | ltc2485_wait_conv(data); | |
44 | ||
45 | ret = i2c_master_recv(client, (char *)&buf, 4); | |
46 | if (ret < 0) { | |
47 | dev_err(&client->dev, "i2c_master_recv failed\n"); | |
48 | return ret; | |
49 | } | |
50 | data->time_prev = ktime_get(); | |
51 | *val = sign_extend32(be32_to_cpu(buf) >> 6, 24); | |
52 | ||
53 | return ret; | |
54 | } | |
55 | ||
56 | static int ltc2485_read_raw(struct iio_dev *indio_dev, | |
57 | struct iio_chan_spec const *chan, | |
58 | int *val, int *val2, long mask) | |
59 | { | |
60 | struct ltc2485_data *data = iio_priv(indio_dev); | |
61 | int ret; | |
62 | ||
63 | if (mask == IIO_CHAN_INFO_RAW) { | |
64 | ret = ltc2485_read(data, val); | |
65 | if (ret < 0) | |
66 | return ret; | |
67 | ||
68 | return IIO_VAL_INT; | |
69 | ||
70 | } else if (mask == IIO_CHAN_INFO_SCALE) { | |
71 | *val = 5000; /* on board vref millivolts */ | |
72 | *val2 = 25; /* 25 (24 + sign) data bits */ | |
73 | return IIO_VAL_FRACTIONAL_LOG2; | |
74 | ||
75 | } else { | |
76 | return -EINVAL; | |
77 | } | |
78 | } | |
79 | ||
80 | static const struct iio_chan_spec ltc2485_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_info ltc2485_info = { | |
89 | .read_raw = ltc2485_read_raw, | |
8c9e7b1b AS |
90 | }; |
91 | ||
92 | static int ltc2485_probe(struct i2c_client *client, | |
93 | const struct i2c_device_id *id) | |
94 | { | |
95 | struct iio_dev *indio_dev; | |
96 | struct ltc2485_data *data; | |
97 | int ret; | |
98 | ||
99 | if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C | | |
100 | I2C_FUNC_SMBUS_WRITE_BYTE)) | |
101 | return -EOPNOTSUPP; | |
102 | ||
103 | indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); | |
104 | if (!indio_dev) | |
105 | return -ENOMEM; | |
106 | ||
107 | data = iio_priv(indio_dev); | |
108 | i2c_set_clientdata(client, indio_dev); | |
109 | data->client = client; | |
110 | ||
111 | indio_dev->dev.parent = &client->dev; | |
112 | indio_dev->name = id->name; | |
113 | indio_dev->info = <c2485_info; | |
114 | indio_dev->modes = INDIO_DIRECT_MODE; | |
115 | indio_dev->channels = ltc2485_channel; | |
116 | indio_dev->num_channels = ARRAY_SIZE(ltc2485_channel); | |
117 | ||
118 | ret = i2c_smbus_write_byte(data->client, LTC2485_CONFIG_DEFAULT); | |
119 | if (ret < 0) | |
120 | return ret; | |
121 | ||
122 | data->time_prev = ktime_get(); | |
123 | ||
124 | return devm_iio_device_register(&client->dev, indio_dev); | |
125 | } | |
126 | ||
127 | static const struct i2c_device_id ltc2485_id[] = { | |
128 | { "ltc2485", 0 }, | |
129 | { } | |
130 | }; | |
131 | MODULE_DEVICE_TABLE(i2c, ltc2485_id); | |
132 | ||
133 | static struct i2c_driver ltc2485_driver = { | |
134 | .driver = { | |
135 | .name = "ltc2485", | |
136 | }, | |
137 | .probe = ltc2485_probe, | |
138 | .id_table = ltc2485_id, | |
139 | }; | |
140 | module_i2c_driver(ltc2485_driver); | |
141 | ||
142 | MODULE_AUTHOR("Alison Schofield <amsfield22@gmail.com>"); | |
143 | MODULE_DESCRIPTION("Linear Technology LTC2485 ADC driver"); | |
144 | MODULE_LICENSE("GPL v2"); |