1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-only
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * ltc2497.c - Driver for Analog Devices/Linear Technology LTC2497 ADC
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Copyright (C) 2017 Analog Devices Inc.
6*4882a593Smuzhiyun *
7*4882a593Smuzhiyun * Datasheet: http://cds.linear.com/docs/en/datasheet/2497fd.pdf
8*4882a593Smuzhiyun */
9*4882a593Smuzhiyun
10*4882a593Smuzhiyun #include <linux/i2c.h>
11*4882a593Smuzhiyun #include <linux/iio/iio.h>
12*4882a593Smuzhiyun #include <linux/iio/driver.h>
13*4882a593Smuzhiyun #include <linux/module.h>
14*4882a593Smuzhiyun #include <linux/mod_devicetable.h>
15*4882a593Smuzhiyun
16*4882a593Smuzhiyun #include "ltc2497.h"
17*4882a593Smuzhiyun
18*4882a593Smuzhiyun struct ltc2497_driverdata {
19*4882a593Smuzhiyun /* this must be the first member */
20*4882a593Smuzhiyun struct ltc2497core_driverdata common_ddata;
21*4882a593Smuzhiyun struct i2c_client *client;
22*4882a593Smuzhiyun /*
23*4882a593Smuzhiyun * DMA (thus cache coherency maintenance) requires the
24*4882a593Smuzhiyun * transfer buffers to live in their own cache lines.
25*4882a593Smuzhiyun */
26*4882a593Smuzhiyun __be32 buf ____cacheline_aligned;
27*4882a593Smuzhiyun };
28*4882a593Smuzhiyun
ltc2497_result_and_measure(struct ltc2497core_driverdata * ddata,u8 address,int * val)29*4882a593Smuzhiyun static int ltc2497_result_and_measure(struct ltc2497core_driverdata *ddata,
30*4882a593Smuzhiyun u8 address, int *val)
31*4882a593Smuzhiyun {
32*4882a593Smuzhiyun struct ltc2497_driverdata *st =
33*4882a593Smuzhiyun container_of(ddata, struct ltc2497_driverdata, common_ddata);
34*4882a593Smuzhiyun int ret;
35*4882a593Smuzhiyun
36*4882a593Smuzhiyun if (val) {
37*4882a593Smuzhiyun ret = i2c_master_recv(st->client, (char *)&st->buf, 3);
38*4882a593Smuzhiyun if (ret < 0) {
39*4882a593Smuzhiyun dev_err(&st->client->dev, "i2c_master_recv failed\n");
40*4882a593Smuzhiyun return ret;
41*4882a593Smuzhiyun }
42*4882a593Smuzhiyun
43*4882a593Smuzhiyun *val = (be32_to_cpu(st->buf) >> 14) - (1 << 17);
44*4882a593Smuzhiyun
45*4882a593Smuzhiyun /*
46*4882a593Smuzhiyun * The part started a new conversion at the end of the above i2c
47*4882a593Smuzhiyun * transfer, so if the address didn't change since the last call
48*4882a593Smuzhiyun * everything is fine and we can return early.
49*4882a593Smuzhiyun * If not (which should only happen when some sort of bulk
50*4882a593Smuzhiyun * conversion is implemented) we have to program the new
51*4882a593Smuzhiyun * address. Note that this probably fails as the conversion that
52*4882a593Smuzhiyun * was triggered above is like not complete yet and the two
53*4882a593Smuzhiyun * operations have to be done in a single transfer.
54*4882a593Smuzhiyun */
55*4882a593Smuzhiyun if (ddata->addr_prev == address)
56*4882a593Smuzhiyun return 0;
57*4882a593Smuzhiyun }
58*4882a593Smuzhiyun
59*4882a593Smuzhiyun ret = i2c_smbus_write_byte(st->client,
60*4882a593Smuzhiyun LTC2497_ENABLE | address);
61*4882a593Smuzhiyun if (ret)
62*4882a593Smuzhiyun dev_err(&st->client->dev, "i2c transfer failed: %pe\n",
63*4882a593Smuzhiyun ERR_PTR(ret));
64*4882a593Smuzhiyun return ret;
65*4882a593Smuzhiyun }
66*4882a593Smuzhiyun
ltc2497_probe(struct i2c_client * client,const struct i2c_device_id * id)67*4882a593Smuzhiyun static int ltc2497_probe(struct i2c_client *client,
68*4882a593Smuzhiyun const struct i2c_device_id *id)
69*4882a593Smuzhiyun {
70*4882a593Smuzhiyun struct iio_dev *indio_dev;
71*4882a593Smuzhiyun struct ltc2497_driverdata *st;
72*4882a593Smuzhiyun struct device *dev = &client->dev;
73*4882a593Smuzhiyun
74*4882a593Smuzhiyun if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
75*4882a593Smuzhiyun I2C_FUNC_SMBUS_WRITE_BYTE))
76*4882a593Smuzhiyun return -EOPNOTSUPP;
77*4882a593Smuzhiyun
78*4882a593Smuzhiyun indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
79*4882a593Smuzhiyun if (!indio_dev)
80*4882a593Smuzhiyun return -ENOMEM;
81*4882a593Smuzhiyun
82*4882a593Smuzhiyun st = iio_priv(indio_dev);
83*4882a593Smuzhiyun i2c_set_clientdata(client, indio_dev);
84*4882a593Smuzhiyun st->client = client;
85*4882a593Smuzhiyun st->common_ddata.result_and_measure = ltc2497_result_and_measure;
86*4882a593Smuzhiyun
87*4882a593Smuzhiyun return ltc2497core_probe(dev, indio_dev);
88*4882a593Smuzhiyun }
89*4882a593Smuzhiyun
ltc2497_remove(struct i2c_client * client)90*4882a593Smuzhiyun static int ltc2497_remove(struct i2c_client *client)
91*4882a593Smuzhiyun {
92*4882a593Smuzhiyun struct iio_dev *indio_dev = i2c_get_clientdata(client);
93*4882a593Smuzhiyun
94*4882a593Smuzhiyun ltc2497core_remove(indio_dev);
95*4882a593Smuzhiyun
96*4882a593Smuzhiyun return 0;
97*4882a593Smuzhiyun }
98*4882a593Smuzhiyun
99*4882a593Smuzhiyun static const struct i2c_device_id ltc2497_id[] = {
100*4882a593Smuzhiyun { "ltc2497", 0 },
101*4882a593Smuzhiyun { }
102*4882a593Smuzhiyun };
103*4882a593Smuzhiyun MODULE_DEVICE_TABLE(i2c, ltc2497_id);
104*4882a593Smuzhiyun
105*4882a593Smuzhiyun static const struct of_device_id ltc2497_of_match[] = {
106*4882a593Smuzhiyun { .compatible = "lltc,ltc2497", },
107*4882a593Smuzhiyun {},
108*4882a593Smuzhiyun };
109*4882a593Smuzhiyun MODULE_DEVICE_TABLE(of, ltc2497_of_match);
110*4882a593Smuzhiyun
111*4882a593Smuzhiyun static struct i2c_driver ltc2497_driver = {
112*4882a593Smuzhiyun .driver = {
113*4882a593Smuzhiyun .name = "ltc2497",
114*4882a593Smuzhiyun .of_match_table = ltc2497_of_match,
115*4882a593Smuzhiyun },
116*4882a593Smuzhiyun .probe = ltc2497_probe,
117*4882a593Smuzhiyun .remove = ltc2497_remove,
118*4882a593Smuzhiyun .id_table = ltc2497_id,
119*4882a593Smuzhiyun };
120*4882a593Smuzhiyun module_i2c_driver(ltc2497_driver);
121*4882a593Smuzhiyun
122*4882a593Smuzhiyun MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
123*4882a593Smuzhiyun MODULE_DESCRIPTION("Linear Technology LTC2497 ADC driver");
124*4882a593Smuzhiyun MODULE_LICENSE("GPL v2");
125