2 * ad2s120x.c simple support for the ADI Resolver to Digital Converters: AD2S1200/1205
4 * Copyright (c) 2010-2010 Analog Devices Inc.
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
11 #include <linux/types.h>
12 #include <linux/mutex.h>
13 #include <linux/device.h>
14 #include <linux/spi/spi.h>
15 #include <linux/slab.h>
16 #include <linux/sysfs.h>
17 #include <linux/delay.h>
18 #include <linux/gpio.h>
19 #include <linux/module.h>
24 #define DRV_NAME "ad2s120x"
26 /* input pin sample and rdvel is controlled by driver */
29 /* input clock on serial interface */
30 #define AD2S120X_HZ 8192000
31 /* clock period in nano second */
32 #define AD2S120X_TSCLK (1000000000/AD2S120X_HZ)
34 struct ad2s120x_state {
36 struct spi_device *sdev;
39 u8 rx[2] ____cacheline_aligned;
42 static int ad2s1200_read_raw(struct iio_dev *indio_dev,
43 struct iio_chan_spec const *chan,
50 struct ad2s120x_state *st = iio_priv(indio_dev);
52 mutex_lock(&st->lock);
53 gpio_set_value(st->sample, 0);
54 /* delay (6 * AD2S120X_TSCLK + 20) nano seconds */
56 gpio_set_value(st->sample, 1);
57 gpio_set_value(st->rdvel, !!(chan->type == IIO_ANGL));
58 ret = spi_read(st->sdev, st->rx, 2);
60 mutex_unlock(&st->lock);
66 *val = (((u16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
69 vel = (((s16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
70 vel = (vel << 4) >> 4;
73 mutex_unlock(&st->lock);
76 /* delay (2 * AD2S120X_TSCLK + 20) ns for sample pulse */
78 mutex_unlock(&st->lock);
82 static const struct iio_chan_spec ad2s1200_channels[] = {
94 static const struct iio_info ad2s120x_info = {
95 .read_raw = &ad2s1200_read_raw,
96 .driver_module = THIS_MODULE,
99 static int __devinit ad2s120x_probe(struct spi_device *spi)
101 struct ad2s120x_state *st;
102 struct iio_dev *indio_dev;
104 unsigned short *pins = spi->dev.platform_data;
106 for (pn = 0; pn < AD2S120X_PN; pn++)
107 if (gpio_request_one(pins[pn], GPIOF_DIR_OUT, DRV_NAME)) {
108 pr_err("%s: request gpio pin %d failed\n",
112 indio_dev = iio_allocate_device(sizeof(*st));
113 if (indio_dev == NULL) {
117 spi_set_drvdata(spi, indio_dev);
118 st = iio_priv(indio_dev);
119 mutex_init(&st->lock);
121 st->sample = pins[0];
124 indio_dev->dev.parent = &spi->dev;
125 indio_dev->info = &ad2s120x_info;
126 indio_dev->modes = INDIO_DIRECT_MODE;
127 indio_dev->channels = ad2s1200_channels;
128 indio_dev->num_channels = ARRAY_SIZE(ad2s1200_channels);
130 ret = iio_device_register(indio_dev);
134 spi->max_speed_hz = AD2S120X_HZ;
135 spi->mode = SPI_MODE_3;
141 iio_free_device(indio_dev);
143 for (--pn; pn >= 0; pn--)
148 static int __devexit ad2s120x_remove(struct spi_device *spi)
150 iio_device_unregister(spi_get_drvdata(spi));
155 static struct spi_driver ad2s120x_driver = {
158 .owner = THIS_MODULE,
160 .probe = ad2s120x_probe,
161 .remove = __devexit_p(ad2s120x_remove),
164 static __init int ad2s120x_spi_init(void)
166 return spi_register_driver(&ad2s120x_driver);
168 module_init(ad2s120x_spi_init);
170 static __exit void ad2s120x_spi_exit(void)
172 spi_unregister_driver(&ad2s120x_driver);
174 module_exit(ad2s120x_spi_exit);
176 MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>");
177 MODULE_DESCRIPTION("Analog Devices AD2S1200/1205 Resolver to Digital SPI driver");
178 MODULE_LICENSE("GPL v2");