1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
|
// SPDX-License-Identifier: GPL-2.0-only
/*
* ltc2497.c - Driver for Analog Devices/Linear Technology LTC2497 ADC
*
* Copyright (C) 2017 Analog Devices Inc.
*
* Datasheet: http://cds.linear.com/docs/en/datasheet/2497fd.pdf
*/
#include <linux/i2c.h>
#include <linux/iio/iio.h>
#include <linux/iio/driver.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/property.h>
#include <asm/unaligned.h>
#include "ltc2497.h"
enum ltc2497_chip_type {
TYPE_LTC2497,
TYPE_LTC2499,
};
struct ltc2497_driverdata {
/* this must be the first member */
struct ltc2497core_driverdata common_ddata;
struct i2c_client *client;
u32 recv_size;
/*
* DMA (thus cache coherency maintenance) may require the
* transfer buffers to live in their own cache lines.
*/
union {
__be32 d32;
u8 d8[3];
} data __aligned(IIO_DMA_MINALIGN);
};
static int ltc2497_result_and_measure(struct ltc2497core_driverdata *ddata,
u8 address, int *val)
{
struct ltc2497_driverdata *st =
container_of(ddata, struct ltc2497_driverdata, common_ddata);
int ret;
if (val) {
if (st->recv_size == 3)
ret = i2c_master_recv(st->client, (char *)&st->data.d8,
st->recv_size);
else
ret = i2c_master_recv(st->client, (char *)&st->data.d32,
st->recv_size);
if (ret < 0) {
dev_err(&st->client->dev, "i2c_master_recv failed\n");
return ret;
}
/*
* The data format is 16/24 bit 2s complement, but with an upper sign bit on the
* resolution + 1 position, which is set for positive values only. Given this
* bit's value, subtracting BIT(resolution + 1) from the ADC's result is
* equivalent to a sign extension.
*/
if (st->recv_size == 3) {
*val = (get_unaligned_be24(st->data.d8) >> 6)
- BIT(ddata->chip_info->resolution + 1);
} else {
*val = (be32_to_cpu(st->data.d32) >> 6)
- BIT(ddata->chip_info->resolution + 1);
}
/*
* The part started a new conversion at the end of the above i2c
* transfer, so if the address didn't change since the last call
* everything is fine and we can return early.
* If not (which should only happen when some sort of bulk
* conversion is implemented) we have to program the new
* address. Note that this probably fails as the conversion that
* was triggered above is like not complete yet and the two
* operations have to be done in a single transfer.
*/
if (ddata->addr_prev == address)
return 0;
}
ret = i2c_smbus_write_byte(st->client,
LTC2497_ENABLE | address);
if (ret)
dev_err(&st->client->dev, "i2c transfer failed: %pe\n",
ERR_PTR(ret));
return ret;
}
static int ltc2497_probe(struct i2c_client *client)
{
const struct i2c_device_id *id = i2c_client_get_device_id(client);
const struct ltc2497_chip_info *chip_info;
struct iio_dev *indio_dev;
struct ltc2497_driverdata *st;
struct device *dev = &client->dev;
u32 resolution;
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
I2C_FUNC_SMBUS_WRITE_BYTE))
return -EOPNOTSUPP;
indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
if (!indio_dev)
return -ENOMEM;
st = iio_priv(indio_dev);
i2c_set_clientdata(client, indio_dev);
st->client = client;
st->common_ddata.result_and_measure = ltc2497_result_and_measure;
chip_info = device_get_match_data(dev);
if (!chip_info)
chip_info = (const struct ltc2497_chip_info *)id->driver_data;
st->common_ddata.chip_info = chip_info;
resolution = chip_info->resolution;
st->recv_size = BITS_TO_BYTES(resolution) + 1;
return ltc2497core_probe(dev, indio_dev);
}
static void ltc2497_remove(struct i2c_client *client)
{
struct iio_dev *indio_dev = i2c_get_clientdata(client);
ltc2497core_remove(indio_dev);
}
static const struct ltc2497_chip_info ltc2497_info[] = {
[TYPE_LTC2497] = {
.resolution = 16,
.name = NULL,
},
[TYPE_LTC2499] = {
.resolution = 24,
.name = "ltc2499",
},
};
static const struct i2c_device_id ltc2497_id[] = {
{ "ltc2497", (kernel_ulong_t)<c2497_info[TYPE_LTC2497] },
{ "ltc2499", (kernel_ulong_t)<c2497_info[TYPE_LTC2499] },
{ }
};
MODULE_DEVICE_TABLE(i2c, ltc2497_id);
static const struct of_device_id ltc2497_of_match[] = {
{ .compatible = "lltc,ltc2497", .data = <c2497_info[TYPE_LTC2497] },
{ .compatible = "lltc,ltc2499", .data = <c2497_info[TYPE_LTC2499] },
{},
};
MODULE_DEVICE_TABLE(of, ltc2497_of_match);
static struct i2c_driver ltc2497_driver = {
.driver = {
.name = "ltc2497",
.of_match_table = ltc2497_of_match,
},
.probe = ltc2497_probe,
.remove = ltc2497_remove,
.id_table = ltc2497_id,
};
module_i2c_driver(ltc2497_driver);
MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
MODULE_DESCRIPTION("Linear Technology LTC2497 ADC driver");
MODULE_LICENSE("GPL v2");
|
