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 #include <linux/property.h>
19
20 #include "ltc2497.h"
21
22 struct ltc2496_driverdata {
23 /* this must be the first member */
24 struct ltc2497core_driverdata common_ddata;
25 struct spi_device *spi;
26
27 /*
28 * DMA (thus cache coherency maintenance) may require the
29 * transfer buffers to live in their own cache lines.
30 */
31 unsigned char rxbuf[3] __aligned(IIO_DMA_MINALIGN);
32 unsigned char txbuf[3];
33 };
34
ltc2496_result_and_measure(struct ltc2497core_driverdata * ddata,u8 address,int * val)35 static int ltc2496_result_and_measure(struct ltc2497core_driverdata *ddata,
36 u8 address, int *val)
37 {
38 struct ltc2496_driverdata *st =
39 container_of(ddata, struct ltc2496_driverdata, common_ddata);
40 struct spi_transfer t = {
41 .tx_buf = st->txbuf,
42 .rx_buf = st->rxbuf,
43 .len = sizeof(st->txbuf),
44 };
45 int ret;
46
47 st->txbuf[0] = LTC2497_ENABLE | address;
48
49 ret = spi_sync_transfer(st->spi, &t, 1);
50 if (ret < 0) {
51 dev_err(&st->spi->dev, "spi_sync_transfer failed: %pe\n",
52 ERR_PTR(ret));
53 return ret;
54 }
55
56 if (val)
57 *val = ((st->rxbuf[0] & 0x3f) << 12 |
58 st->rxbuf[1] << 4 | st->rxbuf[2] >> 4) -
59 (1 << 17);
60
61 return 0;
62 }
63
ltc2496_probe(struct spi_device * spi)64 static int ltc2496_probe(struct spi_device *spi)
65 {
66 struct iio_dev *indio_dev;
67 struct ltc2496_driverdata *st;
68 struct device *dev = &spi->dev;
69
70 indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
71 if (!indio_dev)
72 return -ENOMEM;
73
74 st = iio_priv(indio_dev);
75 spi_set_drvdata(spi, indio_dev);
76 st->spi = spi;
77 st->common_ddata.result_and_measure = ltc2496_result_and_measure;
78 st->common_ddata.chip_info = device_get_match_data(dev);
79
80 return ltc2497core_probe(dev, indio_dev);
81 }
82
ltc2496_remove(struct spi_device * spi)83 static void ltc2496_remove(struct spi_device *spi)
84 {
85 struct iio_dev *indio_dev = spi_get_drvdata(spi);
86
87 ltc2497core_remove(indio_dev);
88 }
89
90 static const struct ltc2497_chip_info ltc2496_info = {
91 .resolution = 16,
92 .name = NULL,
93 };
94
95 static const struct of_device_id ltc2496_of_match[] = {
96 { .compatible = "lltc,ltc2496", .data = <c2496_info, },
97 {},
98 };
99 MODULE_DEVICE_TABLE(of, ltc2496_of_match);
100
101 static struct spi_driver ltc2496_driver = {
102 .driver = {
103 .name = "ltc2496",
104 .of_match_table = ltc2496_of_match,
105 },
106 .probe = ltc2496_probe,
107 .remove = ltc2496_remove,
108 };
109 module_spi_driver(ltc2496_driver);
110
111 MODULE_AUTHOR("Uwe Kleine-König <u.kleine-könig@pengutronix.de>");
112 MODULE_DESCRIPTION("Linear Technology LTC2496 ADC driver");
113 MODULE_LICENSE("GPL v2");
114