1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * ltc2497.c - Driver for Analog Devices/Linear Technology LTC2497 ADC
4 *
5 * Copyright (C) 2017 Analog Devices Inc.
6 *
7 * Datasheet: http://cds.linear.com/docs/en/datasheet/2497fd.pdf
8 */
9
10#include <linux/i2c.h>
11#include <linux/iio/iio.h>
12#include <linux/iio/driver.h>
13#include <linux/module.h>
14#include <linux/mod_devicetable.h>
15
16#include "ltc2497.h"
17
18struct ltc2497_driverdata {
19	/* this must be the first member */
20	struct ltc2497core_driverdata common_ddata;
21	struct i2c_client *client;
22	/*
23	 * DMA (thus cache coherency maintenance) requires the
24	 * transfer buffers to live in their own cache lines.
25	 */
26	__be32 buf ____cacheline_aligned;
27};
28
29static int ltc2497_result_and_measure(struct ltc2497core_driverdata *ddata,
30				      u8 address, int *val)
31{
32	struct ltc2497_driverdata *st =
33		container_of(ddata, struct ltc2497_driverdata, common_ddata);
34	int ret;
35
36	if (val) {
37		ret = i2c_master_recv(st->client, (char *)&st->buf, 3);
38		if (ret < 0) {
39			dev_err(&st->client->dev, "i2c_master_recv failed\n");
40			return ret;
41		}
42
43		*val = (be32_to_cpu(st->buf) >> 14) - (1 << 17);
44
45		/*
46		 * The part started a new conversion at the end of the above i2c
47		 * transfer, so if the address didn't change since the last call
48		 * everything is fine and we can return early.
49		 * If not (which should only happen when some sort of bulk
50		 * conversion is implemented) we have to program the new
51		 * address. Note that this probably fails as the conversion that
52		 * was triggered above is like not complete yet and the two
53		 * operations have to be done in a single transfer.
54		 */
55		if (ddata->addr_prev == address)
56			return 0;
57	}
58
59	ret = i2c_smbus_write_byte(st->client,
60				   LTC2497_ENABLE | address);
61	if (ret)
62		dev_err(&st->client->dev, "i2c transfer failed: %pe\n",
63			ERR_PTR(ret));
64	return ret;
65}
66
67static int ltc2497_probe(struct i2c_client *client,
68			 const struct i2c_device_id *id)
69{
70	struct iio_dev *indio_dev;
71	struct ltc2497_driverdata *st;
72	struct device *dev = &client->dev;
73
74	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
75				     I2C_FUNC_SMBUS_WRITE_BYTE))
76		return -EOPNOTSUPP;
77
78	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
79	if (!indio_dev)
80		return -ENOMEM;
81
82	st = iio_priv(indio_dev);
83	i2c_set_clientdata(client, indio_dev);
84	st->client = client;
85	st->common_ddata.result_and_measure = ltc2497_result_and_measure;
86
87	return ltc2497core_probe(dev, indio_dev);
88}
89
90static int ltc2497_remove(struct i2c_client *client)
91{
92	struct iio_dev *indio_dev = i2c_get_clientdata(client);
93
94	ltc2497core_remove(indio_dev);
95
96	return 0;
97}
98
99static const struct i2c_device_id ltc2497_id[] = {
100	{ "ltc2497", 0 },
101	{ }
102};
103MODULE_DEVICE_TABLE(i2c, ltc2497_id);
104
105static const struct of_device_id ltc2497_of_match[] = {
106	{ .compatible = "lltc,ltc2497", },
107	{},
108};
109MODULE_DEVICE_TABLE(of, ltc2497_of_match);
110
111static struct i2c_driver ltc2497_driver = {
112	.driver = {
113		.name = "ltc2497",
114		.of_match_table = ltc2497_of_match,
115	},
116	.probe = ltc2497_probe,
117	.remove = ltc2497_remove,
118	.id_table = ltc2497_id,
119};
120module_i2c_driver(ltc2497_driver);
121
122MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
123MODULE_DESCRIPTION("Linear Technology LTC2497 ADC driver");
124MODULE_LICENSE("GPL v2");
125