1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * ad2s1200.c simple support for the ADI Resolver to Digital Converters:
  4 * AD2S1200/1205
  5 *
  6 * Copyright (c) 2018-2018 David Veenstra <davidjulianveenstra@gmail.com>
  7 * Copyright (c) 2010-2010 Analog Devices Inc.
  8 */
  9
 10#include <linux/bitops.h>
 11#include <linux/delay.h>
 12#include <linux/device.h>
 13#include <linux/gpio/consumer.h>
 14#include <linux/module.h>
 15#include <linux/mutex.h>
 16#include <linux/spi/spi.h>
 17#include <linux/sysfs.h>
 18#include <linux/types.h>
 19
 20#include <linux/iio/iio.h>
 21#include <linux/iio/sysfs.h>
 22
 23#define DRV_NAME "ad2s1200"
 24
 25/* input clock on serial interface */
 26#define AD2S1200_HZ	8192000
 27/* clock period in nano second */
 28#define AD2S1200_TSCLK	(1000000000 / AD2S1200_HZ)
 29
 30/**
 31 * struct ad2s1200_state - driver instance specific data.
 32 * @lock:	protects both the GPIO pins and the rx buffer.
 33 * @sdev:	spi device.
 34 * @sample:	GPIO pin SAMPLE.
 35 * @rdvel:	GPIO pin RDVEL.
 36 * @rx:		buffer for spi transfers.
 37 */
 38struct ad2s1200_state {
 39	struct mutex lock;
 40	struct spi_device *sdev;
 41	struct gpio_desc *sample;
 42	struct gpio_desc *rdvel;
 43	__be16 rx ____cacheline_aligned;
 44};
 45
 46static int ad2s1200_read_raw(struct iio_dev *indio_dev,
 47			     struct iio_chan_spec const *chan,
 48			     int *val,
 49			     int *val2,
 50			     long m)
 51{
 52	struct ad2s1200_state *st = iio_priv(indio_dev);
 53	int ret;
 54
 55	switch (m) {
 56	case IIO_CHAN_INFO_SCALE:
 57		switch (chan->type) {
 58		case IIO_ANGL:
 59			/* 2 * Pi / (2^12 - 1) ~= 0.001534355 */
 60			*val = 0;
 61			*val2 = 1534355;
 62			return IIO_VAL_INT_PLUS_NANO;
 63		case IIO_ANGL_VEL:
 64			/* 2 * Pi ~= 6.283185 */
 65			*val = 6;
 66			*val2 = 283185;
 67			return IIO_VAL_INT_PLUS_MICRO;
 68		default:
 69			return -EINVAL;
 70		}
 71		break;
 72	case IIO_CHAN_INFO_RAW:
 73		mutex_lock(&st->lock);
 74		gpiod_set_value(st->sample, 0);
 75
 76		/* delay (6 * AD2S1200_TSCLK + 20) nano seconds */
 77		udelay(1);
 78		gpiod_set_value(st->sample, 1);
 79		gpiod_set_value(st->rdvel, !!(chan->type == IIO_ANGL));
 80
 81		ret = spi_read(st->sdev, &st->rx, 2);
 82		if (ret < 0) {
 83			mutex_unlock(&st->lock);
 84			return ret;
 85		}
 86
 87		switch (chan->type) {
 88		case IIO_ANGL:
 89			*val = be16_to_cpup(&st->rx) >> 4;
 90			break;
 91		case IIO_ANGL_VEL:
 92			*val = sign_extend32(be16_to_cpup(&st->rx) >> 4, 11);
 93			break;
 94		default:
 95			mutex_unlock(&st->lock);
 96			return -EINVAL;
 97		}
 98
 99		/* delay (2 * AD2S1200_TSCLK + 20) ns for sample pulse */
100		udelay(1);
101		mutex_unlock(&st->lock);
102
103		return IIO_VAL_INT;
104	default:
105		break;
106	}
107
108	return -EINVAL;
109}
110
111static const struct iio_chan_spec ad2s1200_channels[] = {
112	{
113		.type = IIO_ANGL,
114		.indexed = 1,
115		.channel = 0,
116		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
117		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
118	}, {
119		.type = IIO_ANGL_VEL,
120		.indexed = 1,
121		.channel = 0,
122		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
123		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
124	}
125};
126
127static const struct iio_info ad2s1200_info = {
128	.read_raw = ad2s1200_read_raw,
129};
130
131static int ad2s1200_probe(struct spi_device *spi)
132{
133	struct ad2s1200_state *st;
134	struct iio_dev *indio_dev;
135	int ret;
136
137	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
138	if (!indio_dev)
139		return -ENOMEM;
140
141	spi_set_drvdata(spi, indio_dev);
142	st = iio_priv(indio_dev);
143	mutex_init(&st->lock);
144	st->sdev = spi;
145
146	st->sample = devm_gpiod_get(&spi->dev, "adi,sample", GPIOD_OUT_LOW);
147	if (IS_ERR(st->sample)) {
148		dev_err(&spi->dev, "Failed to claim SAMPLE gpio: err=%ld\n",
149			PTR_ERR(st->sample));
150		return PTR_ERR(st->sample);
151	}
152
153	st->rdvel = devm_gpiod_get(&spi->dev, "adi,rdvel", GPIOD_OUT_LOW);
154	if (IS_ERR(st->rdvel)) {
155		dev_err(&spi->dev, "Failed to claim RDVEL gpio: err=%ld\n",
156			PTR_ERR(st->rdvel));
157		return PTR_ERR(st->rdvel);
158	}
159
160	indio_dev->info = &ad2s1200_info;
161	indio_dev->modes = INDIO_DIRECT_MODE;
162	indio_dev->channels = ad2s1200_channels;
163	indio_dev->num_channels = ARRAY_SIZE(ad2s1200_channels);
164	indio_dev->name = spi_get_device_id(spi)->name;
165
166	spi->max_speed_hz = AD2S1200_HZ;
167	spi->mode = SPI_MODE_3;
168	ret = spi_setup(spi);
169
170	if (ret < 0) {
171		dev_err(&spi->dev, "spi_setup failed!\n");
172		return ret;
173	}
174
175	return devm_iio_device_register(&spi->dev, indio_dev);
176}
177
178static const struct of_device_id ad2s1200_of_match[] = {
179	{ .compatible = "adi,ad2s1200", },
180	{ .compatible = "adi,ad2s1205", },
181	{ }
182};
183MODULE_DEVICE_TABLE(of, ad2s1200_of_match);
184
185static const struct spi_device_id ad2s1200_id[] = {
186	{ "ad2s1200" },
187	{ "ad2s1205" },
188	{}
189};
190MODULE_DEVICE_TABLE(spi, ad2s1200_id);
191
192static struct spi_driver ad2s1200_driver = {
193	.driver = {
194		.name = DRV_NAME,
195		.of_match_table = of_match_ptr(ad2s1200_of_match),
196	},
197	.probe = ad2s1200_probe,
198	.id_table = ad2s1200_id,
199};
200module_spi_driver(ad2s1200_driver);
201
202MODULE_AUTHOR("David Veenstra <davidjulianveenstra@gmail.com>");
203MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>");
204MODULE_DESCRIPTION("Analog Devices AD2S1200/1205 Resolver to Digital SPI driver");
205MODULE_LICENSE("GPL v2");