1/*
2 * ad2s1200.c simple support for the ADI Resolver to Digital Converters:
3 * AD2S1200/1205
4 *
5 * Copyright (c) 2010-2010 Analog Devices Inc.
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 *
11 */
12#include <linux/types.h>
13#include <linux/mutex.h>
14#include <linux/device.h>
15#include <linux/spi/spi.h>
16#include <linux/slab.h>
17#include <linux/sysfs.h>
18#include <linux/delay.h>
19#include <linux/gpio.h>
20#include <linux/module.h>
21#include <linux/bitops.h>
22
23#include <linux/iio/iio.h>
24#include <linux/iio/sysfs.h>
25
26#define DRV_NAME "ad2s1200"
27
28/* input pin sample and rdvel is controlled by driver */
29#define AD2S1200_PN	2
30
31/* input clock on serial interface */
32#define AD2S1200_HZ	8192000
33/* clock period in nano second */
34#define AD2S1200_TSCLK	(1000000000/AD2S1200_HZ)
35
36struct ad2s1200_state {
37	struct mutex lock;
38	struct spi_device *sdev;
39	int sample;
40	int rdvel;
41	u8 rx[2] ____cacheline_aligned;
42};
43
44static int ad2s1200_read_raw(struct iio_dev *indio_dev,
45			   struct iio_chan_spec const *chan,
46			   int *val,
47			   int *val2,
48			   long m)
49{
50	int ret = 0;
51	s16 vel;
52	struct ad2s1200_state *st = iio_priv(indio_dev);
53
54	mutex_lock(&st->lock);
55	gpio_set_value(st->sample, 0);
56	/* delay (6 * AD2S1200_TSCLK + 20) nano seconds */
57	udelay(1);
58	gpio_set_value(st->sample, 1);
59	gpio_set_value(st->rdvel, !!(chan->type == IIO_ANGL));
60	ret = spi_read(st->sdev, st->rx, 2);
61	if (ret < 0) {
62		mutex_unlock(&st->lock);
63		return ret;
64	}
65
66	switch (chan->type) {
67	case IIO_ANGL:
68		*val = (((u16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
69		break;
70	case IIO_ANGL_VEL:
71		vel = (((s16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
72		vel = sign_extend32(vel, 11);
73		*val = vel;
74		break;
75	default:
76		mutex_unlock(&st->lock);
77		return -EINVAL;
78	}
79	/* delay (2 * AD2S1200_TSCLK + 20) ns for sample pulse */
80	udelay(1);
81	mutex_unlock(&st->lock);
82	return IIO_VAL_INT;
83}
84
85static const struct iio_chan_spec ad2s1200_channels[] = {
86	{
87		.type = IIO_ANGL,
88		.indexed = 1,
89		.channel = 0,
90		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
91	}, {
92		.type = IIO_ANGL_VEL,
93		.indexed = 1,
94		.channel = 0,
95		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
96	}
97};
98
99static const struct iio_info ad2s1200_info = {
100	.read_raw = &ad2s1200_read_raw,
101	.driver_module = THIS_MODULE,
102};
103
104static int ad2s1200_probe(struct spi_device *spi)
105{
106	struct ad2s1200_state *st;
107	struct iio_dev *indio_dev;
108	int pn, ret = 0;
109	unsigned short *pins = spi->dev.platform_data;
110
111	for (pn = 0; pn < AD2S1200_PN; pn++) {
112		ret = devm_gpio_request_one(&spi->dev, pins[pn], GPIOF_DIR_OUT,
113					    DRV_NAME);
114		if (ret) {
115			dev_err(&spi->dev, "request gpio pin %d failed\n",
116							pins[pn]);
117			return ret;
118		}
119	}
120	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
121	if (!indio_dev)
122		return -ENOMEM;
123	spi_set_drvdata(spi, indio_dev);
124	st = iio_priv(indio_dev);
125	mutex_init(&st->lock);
126	st->sdev = spi;
127	st->sample = pins[0];
128	st->rdvel = pins[1];
129
130	indio_dev->dev.parent = &spi->dev;
131	indio_dev->info = &ad2s1200_info;
132	indio_dev->modes = INDIO_DIRECT_MODE;
133	indio_dev->channels = ad2s1200_channels;
134	indio_dev->num_channels = ARRAY_SIZE(ad2s1200_channels);
135	indio_dev->name = spi_get_device_id(spi)->name;
136
137	ret = devm_iio_device_register(&spi->dev, indio_dev);
138	if (ret)
139		return ret;
140
141	spi->max_speed_hz = AD2S1200_HZ;
142	spi->mode = SPI_MODE_3;
143	spi_setup(spi);
144
145	return 0;
146}
147
148static const struct spi_device_id ad2s1200_id[] = {
149	{ "ad2s1200" },
150	{ "ad2s1205" },
151	{}
152};
153MODULE_DEVICE_TABLE(spi, ad2s1200_id);
154
155static struct spi_driver ad2s1200_driver = {
156	.driver = {
157		.name = DRV_NAME,
158	},
159	.probe = ad2s1200_probe,
160	.id_table = ad2s1200_id,
161};
162module_spi_driver(ad2s1200_driver);
163
164MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>");
165MODULE_DESCRIPTION("Analog Devices AD2S1200/1205 Resolver to Digital SPI driver");
166MODULE_LICENSE("GPL v2");
167