1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * ltc2496.c - Driver for Analog Devices/Linear Technology LTC2496 ADC
4 *
5 * Based on ltc2497.c which has
6 * Copyright (C) 2017 Analog Devices Inc.
7 *
8 * Licensed under the GPL-2.
9 *
10 * Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/2496fc.pdf
11 */
12
13 #include <linux/spi/spi.h>
14 #include <linux/iio/iio.h>
15 #include <linux/iio/driver.h>
16 #include <linux/module.h>
17 #include <linux/mod_devicetable.h>
18
19 #include "ltc2497.h"
20
21 struct ltc2496_driverdata {
22 /* this must be the first member */
23 struct ltc2497core_driverdata common_ddata;
24 struct spi_device *spi;
25
26 /*
27 * DMA (thus cache coherency maintenance) requires the
28 * transfer buffers to live in their own cache lines.
29 */
30 unsigned char rxbuf[3] ____cacheline_aligned;
31 unsigned char txbuf[3];
32 };
33
ltc2496_result_and_measure(struct ltc2497core_driverdata * ddata,u8 address,int * val)34 static int ltc2496_result_and_measure(struct ltc2497core_driverdata *ddata,
35 u8 address, int *val)
36 {
37 struct ltc2496_driverdata *st =
38 container_of(ddata, struct ltc2496_driverdata, common_ddata);
39 struct spi_transfer t = {
40 .tx_buf = st->txbuf,
41 .rx_buf = st->rxbuf,
42 .len = sizeof(st->txbuf),
43 };
44 int ret;
45
46 st->txbuf[0] = LTC2497_ENABLE | address;
47
48 ret = spi_sync_transfer(st->spi, &t, 1);
49 if (ret < 0) {
50 dev_err(&st->spi->dev, "spi_sync_transfer failed: %pe\n",
51 ERR_PTR(ret));
52 return ret;
53 }
54
55 if (val)
56 *val = ((st->rxbuf[0] & 0x3f) << 12 |
57 st->rxbuf[1] << 4 | st->rxbuf[2] >> 4) -
58 (1 << 17);
59
60 return 0;
61 }
62
ltc2496_probe(struct spi_device * spi)63 static int ltc2496_probe(struct spi_device *spi)
64 {
65 struct iio_dev *indio_dev;
66 struct ltc2496_driverdata *st;
67 struct device *dev = &spi->dev;
68
69 indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
70 if (!indio_dev)
71 return -ENOMEM;
72
73 st = iio_priv(indio_dev);
74 spi_set_drvdata(spi, indio_dev);
75 st->spi = spi;
76 st->common_ddata.result_and_measure = ltc2496_result_and_measure;
77
78 return ltc2497core_probe(dev, indio_dev);
79 }
80
ltc2496_remove(struct spi_device * spi)81 static int ltc2496_remove(struct spi_device *spi)
82 {
83 struct iio_dev *indio_dev = spi_get_drvdata(spi);
84
85 ltc2497core_remove(indio_dev);
86
87 return 0;
88 }
89
90 static const struct of_device_id ltc2496_of_match[] = {
91 { .compatible = "lltc,ltc2496", },
92 {},
93 };
94 MODULE_DEVICE_TABLE(of, ltc2496_of_match);
95
96 static struct spi_driver ltc2496_driver = {
97 .driver = {
98 .name = "ltc2496",
99 .of_match_table = ltc2496_of_match,
100 },
101 .probe = ltc2496_probe,
102 .remove = ltc2496_remove,
103 };
104 module_spi_driver(ltc2496_driver);
105
106 MODULE_AUTHOR("Uwe Kleine-König <u.kleine-könig@pengutronix.de>");
107 MODULE_DESCRIPTION("Linear Technology LTC2496 ADC driver");
108 MODULE_LICENSE("GPL v2");
109