xref: /openbmc/linux/drivers/iio/adc/ltc2496.c (revision ac73d4bf)
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 
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 
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 
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 = &ltc2496_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