[go: nahoru, domu]
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
22#include <linux/iio/iio.h>
23#include <linux/iio/sysfs.h>
24
25#define DRV_NAME "ad2s1200"
26
27/* input pin sample and rdvel is controlled by driver */
28#define AD2S1200_PN	2
29
30/* input clock on serial interface */
31#define AD2S1200_HZ	8192000
32/* clock period in nano second */
33#define AD2S1200_TSCLK	(1000000000/AD2S1200_HZ)
34
35struct ad2s1200_state {
36	struct mutex lock;
37	struct spi_device *sdev;
38	int sample;
39	int rdvel;
40	u8 rx[2] ____cacheline_aligned;
41};
42
43static int ad2s1200_read_raw(struct iio_dev *indio_dev,
44			   struct iio_chan_spec const *chan,
45			   int *val,
46			   int *val2,
47			   long m)
48{
49	int ret = 0;
50	s16 vel;
51	struct ad2s1200_state *st = iio_priv(indio_dev);
52
53	mutex_lock(&st->lock);
54	gpio_set_value(st->sample, 0);
55	/* delay (6 * AD2S1200_TSCLK + 20) nano seconds */
56	udelay(1);
57	gpio_set_value(st->sample, 1);
58	gpio_set_value(st->rdvel, !!(chan->type == IIO_ANGL));
59	ret = spi_read(st->sdev, st->rx, 2);
60	if (ret < 0) {
61		mutex_unlock(&st->lock);
62		return ret;
63	}
64
65	switch (chan->type) {
66	case IIO_ANGL:
67		*val = (((u16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
68		break;
69	case IIO_ANGL_VEL:
70		vel = (((s16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
71		vel = (vel << 4) >> 4;
72		*val = vel;
73		break;
74	default:
75		mutex_unlock(&st->lock);
76		return -EINVAL;
77	}
78	/* delay (2 * AD2S1200_TSCLK + 20) ns for sample pulse */
79	udelay(1);
80	mutex_unlock(&st->lock);
81	return IIO_VAL_INT;
82}
83
84static const struct iio_chan_spec ad2s1200_channels[] = {
85	{
86		.type = IIO_ANGL,
87		.indexed = 1,
88		.channel = 0,
89		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
90	}, {
91		.type = IIO_ANGL_VEL,
92		.indexed = 1,
93		.channel = 0,
94		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
95	}
96};
97
98static const struct iio_info ad2s1200_info = {
99	.read_raw = &ad2s1200_read_raw,
100	.driver_module = THIS_MODULE,
101};
102
103static int ad2s1200_probe(struct spi_device *spi)
104{
105	struct ad2s1200_state *st;
106	struct iio_dev *indio_dev;
107	int pn, ret = 0;
108	unsigned short *pins = spi->dev.platform_data;
109
110	for (pn = 0; pn < AD2S1200_PN; pn++) {
111		ret = devm_gpio_request_one(&spi->dev, pins[pn], GPIOF_DIR_OUT,
112					    DRV_NAME);
113		if (ret) {
114			dev_err(&spi->dev, "request gpio pin %d failed\n",
115							pins[pn]);
116			return ret;
117		}
118	}
119	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
120	if (!indio_dev)
121		return -ENOMEM;
122	spi_set_drvdata(spi, indio_dev);
123	st = iio_priv(indio_dev);
124	mutex_init(&st->lock);
125	st->sdev = spi;
126	st->sample = pins[0];
127	st->rdvel = pins[1];
128
129	indio_dev->dev.parent = &spi->dev;
130	indio_dev->info = &ad2s1200_info;
131	indio_dev->modes = INDIO_DIRECT_MODE;
132	indio_dev->channels = ad2s1200_channels;
133	indio_dev->num_channels = ARRAY_SIZE(ad2s1200_channels);
134	indio_dev->name = spi_get_device_id(spi)->name;
135
136	ret = devm_iio_device_register(&spi->dev, indio_dev);
137	if (ret)
138		return ret;
139
140	spi->max_speed_hz = AD2S1200_HZ;
141	spi->mode = SPI_MODE_3;
142	spi_setup(spi);
143
144	return 0;
145}
146
147static const struct spi_device_id ad2s1200_id[] = {
148	{ "ad2s1200" },
149	{ "ad2s1205" },
150	{}
151};
152MODULE_DEVICE_TABLE(spi, ad2s1200_id);
153
154static struct spi_driver ad2s1200_driver = {
155	.driver = {
156		.name = DRV_NAME,
157		.owner = THIS_MODULE,
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