• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
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