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/mod_devicetable.h>
 16#include <linux/mutex.h>
 17#include <linux/spi/spi.h>
 18#include <linux/sysfs.h>
 19#include <linux/types.h>
 20
 21#include <linux/iio/iio.h>
 22#include <linux/iio/sysfs.h>
 23
 24#define DRV_NAME "ad2s1200"
 25
 26/* input clock on serial interface */
 27#define AD2S1200_HZ	8192000
 28/* clock period in nano second */
 29#define AD2S1200_TSCLK	(1000000000 / AD2S1200_HZ)
 30
 31/**
 32 * struct ad2s1200_state - driver instance specific data.
 33 * @lock:	protects both the GPIO pins and the rx buffer.
 34 * @sdev:	spi device.
 35 * @sample:	GPIO pin SAMPLE.
 36 * @rdvel:	GPIO pin RDVEL.
 37 * @rx:		buffer for spi transfers.
 38 */
 39struct ad2s1200_state {
 40	struct mutex lock;
 41	struct spi_device *sdev;
 42	struct gpio_desc *sample;
 43	struct gpio_desc *rdvel;
 44	__be16 rx ____cacheline_aligned;
 45};
 46
 47static int ad2s1200_read_raw(struct iio_dev *indio_dev,
 48			     struct iio_chan_spec const *chan,
 49			     int *val,
 50			     int *val2,
 51			     long m)
 52{
 53	struct ad2s1200_state *st = iio_priv(indio_dev);
 54	int ret;
 55
 56	switch (m) {
 57	case IIO_CHAN_INFO_SCALE:
 58		switch (chan->type) {
 59		case IIO_ANGL:
 60			/* 2 * Pi / (2^12 - 1) ~= 0.001534355 */
 61			*val = 0;
 62			*val2 = 1534355;
 63			return IIO_VAL_INT_PLUS_NANO;
 64		case IIO_ANGL_VEL:
 65			/* 2 * Pi ~= 6.283185 */
 66			*val = 6;
 67			*val2 = 283185;
 68			return IIO_VAL_INT_PLUS_MICRO;
 69		default:
 70			return -EINVAL;
 71		}
 72		break;
 73	case IIO_CHAN_INFO_RAW:
 74		mutex_lock(&st->lock);
 75		gpiod_set_value(st->sample, 0);
 76
 77		/* delay (6 * AD2S1200_TSCLK + 20) nano seconds */
 78		udelay(1);
 79		gpiod_set_value(st->sample, 1);
 80		gpiod_set_value(st->rdvel, !!(chan->type == IIO_ANGL));
 81
 82		ret = spi_read(st->sdev, &st->rx, 2);
 83		if (ret < 0) {
 84			mutex_unlock(&st->lock);
 85			return ret;
 86		}
 87
 88		switch (chan->type) {
 89		case IIO_ANGL:
 90			*val = be16_to_cpup(&st->rx) >> 4;
 91			break;
 92		case IIO_ANGL_VEL:
 93			*val = sign_extend32(be16_to_cpup(&st->rx) >> 4, 11);
 94			break;
 95		default:
 96			mutex_unlock(&st->lock);
 97			return -EINVAL;
 98		}
 99
100		/* delay (2 * AD2S1200_TSCLK + 20) ns for sample pulse */
101		udelay(1);
102		mutex_unlock(&st->lock);
103
104		return IIO_VAL_INT;
105	default:
106		break;
107	}
108
109	return -EINVAL;
110}
111
112static const struct iio_chan_spec ad2s1200_channels[] = {
113	{
114		.type = IIO_ANGL,
115		.indexed = 1,
116		.channel = 0,
117		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
118		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
119	}, {
120		.type = IIO_ANGL_VEL,
121		.indexed = 1,
122		.channel = 0,
123		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
124		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
125	}
126};
127
128static const struct iio_info ad2s1200_info = {
129	.read_raw = ad2s1200_read_raw,
130};
131
132static int ad2s1200_probe(struct spi_device *spi)
133{
134	struct ad2s1200_state *st;
135	struct iio_dev *indio_dev;
136	int ret;
137
138	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
139	if (!indio_dev)
140		return -ENOMEM;
141
142	spi_set_drvdata(spi, indio_dev);
143	st = iio_priv(indio_dev);
144	mutex_init(&st->lock);
145	st->sdev = spi;
146
147	st->sample = devm_gpiod_get(&spi->dev, "adi,sample", GPIOD_OUT_LOW);
148	if (IS_ERR(st->sample)) {
149		dev_err(&spi->dev, "Failed to claim SAMPLE gpio: err=%ld\n",
150			PTR_ERR(st->sample));
151		return PTR_ERR(st->sample);
152	}
153
154	st->rdvel = devm_gpiod_get(&spi->dev, "adi,rdvel", GPIOD_OUT_LOW);
155	if (IS_ERR(st->rdvel)) {
156		dev_err(&spi->dev, "Failed to claim RDVEL gpio: err=%ld\n",
157			PTR_ERR(st->rdvel));
158		return PTR_ERR(st->rdvel);
159	}
160
161	indio_dev->info = &ad2s1200_info;
162	indio_dev->modes = INDIO_DIRECT_MODE;
163	indio_dev->channels = ad2s1200_channels;
164	indio_dev->num_channels = ARRAY_SIZE(ad2s1200_channels);
165	indio_dev->name = spi_get_device_id(spi)->name;
166
167	spi->max_speed_hz = AD2S1200_HZ;
168	spi->mode = SPI_MODE_3;
169	ret = spi_setup(spi);
170
171	if (ret < 0) {
172		dev_err(&spi->dev, "spi_setup failed!\n");
173		return ret;
174	}
175
176	return devm_iio_device_register(&spi->dev, indio_dev);
177}
178
179static const struct of_device_id ad2s1200_of_match[] = {
180	{ .compatible = "adi,ad2s1200", },
181	{ .compatible = "adi,ad2s1205", },
182	{ }
183};
184MODULE_DEVICE_TABLE(of, ad2s1200_of_match);
185
186static const struct spi_device_id ad2s1200_id[] = {
187	{ "ad2s1200" },
188	{ "ad2s1205" },
189	{}
190};
191MODULE_DEVICE_TABLE(spi, ad2s1200_id);
192
193static struct spi_driver ad2s1200_driver = {
194	.driver = {
195		.name = DRV_NAME,
196		.of_match_table = ad2s1200_of_match,
197	},
198	.probe = ad2s1200_probe,
199	.id_table = ad2s1200_id,
200};
201module_spi_driver(ad2s1200_driver);
202
203MODULE_AUTHOR("David Veenstra <davidjulianveenstra@gmail.com>");
204MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>");
205MODULE_DESCRIPTION("Analog Devices AD2S1200/1205 Resolver to Digital SPI driver");
206MODULE_LICENSE("GPL v2");