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
22struct 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
35static 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
64static 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
83static 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
90static const struct ltc2497_chip_info ltc2496_info = {
91	.resolution = 16,
92	.name = NULL,
93};
94
95static const struct of_device_id ltc2496_of_match[] = {
96	{ .compatible = "lltc,ltc2496", .data = &ltc2496_info, },
97	{},
98};
99MODULE_DEVICE_TABLE(of, ltc2496_of_match);
100
101static 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};
109module_spi_driver(ltc2496_driver);
110
111MODULE_AUTHOR("Uwe Kleine-K��nig <u.kleine-k��nig@pengutronix.de>");
112MODULE_DESCRIPTION("Linear Technology LTC2496 ADC driver");
113MODULE_LICENSE("GPL v2");
114