/drivers/staging/iio/resolver/ad2s90.c

  1/*
  2 * ad2s90.c simple support for the ADI Resolver to Digital Converters: AD2S90
  3 *
  4 * Copyright (c) 2010-2010 Analog Devices Inc.
  5 *
  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.
  9 *
 10 */
 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
 18#include "../iio.h"
 19#include "../sysfs.h"
 20
 21#define DRV_NAME "ad2s90"
 22
 23struct ad2s90_state {
 24	struct mutex lock;
 25	struct iio_dev *idev;
 26	struct spi_device *sdev;
 27	u8 rx[2];
 28	u8 tx[2];
 29};
 30
 31static ssize_t ad2s90_show_angular(struct device *dev,
 32			struct device_attribute *attr, char *buf)
 33{
 34	struct spi_message msg;
 35	struct spi_transfer xfer;
 36	int ret;
 37	ssize_t len = 0;
 38	u16 val;
 39	struct iio_dev *idev = dev_get_drvdata(dev);
 40	struct ad2s90_state *st = idev->dev_data;
 41
 42	xfer.len = 1;
 43	xfer.tx_buf = st->tx;
 44	xfer.rx_buf = st->rx;
 45	mutex_lock(&st->lock);
 46
 47	spi_message_init(&msg);
 48	spi_message_add_tail(&xfer, &msg);
 49	ret = spi_sync(st->sdev, &msg);
 50	if (ret)
 51		goto error_ret;
 52	val = (((u16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
 53	len = sprintf(buf, "%d\n", val);
 54error_ret:
 55	mutex_unlock(&st->lock);
 56
 57	return ret ? ret : len;
 58}
 59
 60#define IIO_DEV_ATTR_SIMPLE_RESOLVER(_show) \
 61	IIO_DEVICE_ATTR(angular, S_IRUGO, _show, NULL, 0)
 62
 63static IIO_CONST_ATTR(description,
 64	"Low Cost, Complete 12-Bit Resolver-to-Digital Converter");
 65static IIO_DEV_ATTR_SIMPLE_RESOLVER(ad2s90_show_angular);
 66
 67static struct attribute *ad2s90_attributes[] = {
 68	&iio_const_attr_description.dev_attr.attr,
 69	&iio_dev_attr_angular.dev_attr.attr,
 70	NULL,
 71};
 72
 73static const struct attribute_group ad2s90_attribute_group = {
 74	.name = DRV_NAME,
 75	.attrs = ad2s90_attributes,
 76};
 77
 78static const struct iio_info ad2s90_info = {
 79	.attrs = &ad2s90_attribute_group,
 80	.driver_module = THIS_MODULE,
 81};
 82
 83static int __devinit ad2s90_probe(struct spi_device *spi)
 84{
 85	struct ad2s90_state *st;
 86	int ret = 0;
 87
 88	st = kzalloc(sizeof(*st), GFP_KERNEL);
 89	if (st == NULL) {
 90		ret = -ENOMEM;
 91		goto error_ret;
 92	}
 93	spi_set_drvdata(spi, st);
 94
 95	mutex_init(&st->lock);
 96	st->sdev = spi;
 97
 98	st->idev = iio_allocate_device(0);
 99	if (st->idev == NULL) {
100		ret = -ENOMEM;
101		goto error_free_st;
102	}
103	st->idev->dev.parent = &spi->dev;
104
105	st->idev->info = &ad2s90_info;
106	st->idev->dev_data = (void *)(st);
107	st->idev->modes = INDIO_DIRECT_MODE;
108
109	ret = iio_device_register(st->idev);
110	if (ret)
111		goto error_free_dev;
112
113	/* need 600ns between CS and the first falling edge of SCLK */
114	spi->max_speed_hz = 830000;
115	spi->mode = SPI_MODE_3;
116	spi_setup(spi);
117
118	return 0;
119
120error_free_dev:
121	iio_free_device(st->idev);
122error_free_st:
123	kfree(st);
124error_ret:
125	return ret;
126}
127
128static int __devexit ad2s90_remove(struct spi_device *spi)
129{
130	struct ad2s90_state *st = spi_get_drvdata(spi);
131
132	iio_device_unregister(st->idev);
133	kfree(st);
134
135	return 0;
136}
137
138static struct spi_driver ad2s90_driver = {
139	.driver = {
140		.name = DRV_NAME,
141		.owner = THIS_MODULE,
142	},
143	.probe = ad2s90_probe,
144	.remove = __devexit_p(ad2s90_remove),
145};
146
147static __init int ad2s90_spi_init(void)
148{
149	return spi_register_driver(&ad2s90_driver);
150}
151module_init(ad2s90_spi_init);
152
153static __exit void ad2s90_spi_exit(void)
154{
155	spi_unregister_driver(&ad2s90_driver);
156}
157module_exit(ad2s90_spi_exit);
158
159MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>");
160MODULE_DESCRIPTION("Analog Devices AD2S90 Resolver to Digital SPI driver");
161MODULE_LICENSE("GPL v2");