1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * ltc2485.c - Driver for Linear Technology LTC2485 ADC |
4 | * |
5 | * Copyright (C) 2016 Alison Schofield <amsfield22@gmail.com> |
6 | * |
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(later: ktime_get(), earlier: data->time_prev); |
32 | |
33 | if (time_elapsed < conv_time) |
34 | msleep(msecs: 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, buf: (char *)&buf, count: 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, index: 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, |
90 | }; |
91 | |
92 | static int ltc2485_probe(struct i2c_client *client) |
93 | { |
94 | const struct i2c_device_id *id = i2c_client_get_device_id(client); |
95 | struct iio_dev *indio_dev; |
96 | struct ltc2485_data *data; |
97 | int ret; |
98 | |
99 | if (!i2c_check_functionality(adap: client->adapter, I2C_FUNC_I2C | |
100 | I2C_FUNC_SMBUS_WRITE_BYTE)) |
101 | return -EOPNOTSUPP; |
102 | |
103 | indio_dev = devm_iio_device_alloc(parent: &client->dev, sizeof_priv: sizeof(*data)); |
104 | if (!indio_dev) |
105 | return -ENOMEM; |
106 | |
107 | data = iio_priv(indio_dev); |
108 | i2c_set_clientdata(client, data: indio_dev); |
109 | data->client = client; |
110 | |
111 | indio_dev->name = id->name; |
112 | indio_dev->info = <c2485_info; |
113 | indio_dev->modes = INDIO_DIRECT_MODE; |
114 | indio_dev->channels = ltc2485_channel; |
115 | indio_dev->num_channels = ARRAY_SIZE(ltc2485_channel); |
116 | |
117 | ret = i2c_smbus_write_byte(client: data->client, LTC2485_CONFIG_DEFAULT); |
118 | if (ret < 0) |
119 | return ret; |
120 | |
121 | data->time_prev = ktime_get(); |
122 | |
123 | return devm_iio_device_register(&client->dev, indio_dev); |
124 | } |
125 | |
126 | static const struct i2c_device_id ltc2485_id[] = { |
127 | { "ltc2485" , 0 }, |
128 | { } |
129 | }; |
130 | MODULE_DEVICE_TABLE(i2c, ltc2485_id); |
131 | |
132 | static struct i2c_driver ltc2485_driver = { |
133 | .driver = { |
134 | .name = "ltc2485" , |
135 | }, |
136 | .probe = ltc2485_probe, |
137 | .id_table = ltc2485_id, |
138 | }; |
139 | module_i2c_driver(ltc2485_driver); |
140 | |
141 | MODULE_AUTHOR("Alison Schofield <amsfield22@gmail.com>" ); |
142 | MODULE_DESCRIPTION("Linear Technology LTC2485 ADC driver" ); |
143 | MODULE_LICENSE("GPL v2" ); |
144 | |