/drivers/staging/iio/resolver/ad2s120x.c
https://bitbucket.org/cyanogenmod/android_kernel_asus_tf300t · C · 177 lines · 136 code · 26 blank · 15 comment · 9 complexity · b6cfebde4352d3323edb33e28910a036 MD5 · raw file
- /*
- * ad2s120x.c simple support for the ADI Resolver to Digital Converters: AD2S1200/1205
- *
- * Copyright (c) 2010-2010 Analog Devices Inc.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
- */
- #include <linux/types.h>
- #include <linux/mutex.h>
- #include <linux/device.h>
- #include <linux/spi/spi.h>
- #include <linux/slab.h>
- #include <linux/sysfs.h>
- #include <linux/delay.h>
- #include <linux/gpio.h>
- #include "../iio.h"
- #include "../sysfs.h"
- #define DRV_NAME "ad2s120x"
- /* input pin sample and rdvel is controlled by driver */
- #define AD2S120X_PN 2
- /* input clock on serial interface */
- #define AD2S120X_HZ 8192000
- /* clock period in nano second */
- #define AD2S120X_TSCLK (1000000000/AD2S120X_HZ)
- struct ad2s120x_state {
- struct mutex lock;
- struct spi_device *sdev;
- int sample;
- int rdvel;
- u8 rx[2] ____cacheline_aligned;
- };
- static ssize_t ad2s120x_show_val(struct device *dev,
- struct device_attribute *attr, char *buf)
- {
- int ret = 0;
- ssize_t len = 0;
- u16 pos;
- s16 vel;
- u8 status;
- struct ad2s120x_state *st = iio_priv(dev_get_drvdata(dev));
- struct iio_dev_attr *iattr = to_iio_dev_attr(attr);
- mutex_lock(&st->lock);
- gpio_set_value(st->sample, 0);
- /* delay (6 * AD2S120X_TSCLK + 20) nano seconds */
- udelay(1);
- gpio_set_value(st->sample, 1);
- gpio_set_value(st->rdvel, iattr->address);
- ret = spi_read(st->sdev, st->rx, 2);
- if (ret < 0)
- goto error_ret;
- status = st->rx[1];
- if (iattr->address)
- pos = (((u16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
- else {
- vel = (st->rx[0] & 0x80) ? 0xf000 : 0;
- vel |= (((s16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
- }
- len = sprintf(buf, "%d %c%c%c%c ", iattr->address ? pos : vel,
- (status & 0x8) ? 'P' : 'V',
- (status & 0x4) ? 'd' : '_',
- (status & 0x2) ? 'l' : '_',
- (status & 0x1) ? '1' : '0');
- error_ret:
- /* delay (2 * AD2S120X_TSCLK + 20) ns for sample pulse */
- udelay(1);
- mutex_unlock(&st->lock);
- return ret ? ret : len;
- }
- static IIO_DEVICE_ATTR(pos, S_IRUGO, ad2s120x_show_val, NULL, 1);
- static IIO_DEVICE_ATTR(vel, S_IRUGO, ad2s120x_show_val, NULL, 0);
- static struct attribute *ad2s120x_attributes[] = {
- &iio_dev_attr_pos.dev_attr.attr,
- &iio_dev_attr_vel.dev_attr.attr,
- NULL,
- };
- static const struct attribute_group ad2s120x_attribute_group = {
- .attrs = ad2s120x_attributes,
- };
- static const struct iio_info ad2s120x_info = {
- .attrs = &ad2s120x_attribute_group,
- .driver_module = THIS_MODULE,
- };
- static int __devinit ad2s120x_probe(struct spi_device *spi)
- {
- struct ad2s120x_state *st;
- struct iio_dev *indio_dev;
- int pn, ret = 0;
- unsigned short *pins = spi->dev.platform_data;
- for (pn = 0; pn < AD2S120X_PN; pn++)
- if (gpio_request_one(pins[pn], GPIOF_DIR_OUT, DRV_NAME)) {
- pr_err("%s: request gpio pin %d failed\n",
- DRV_NAME, pins[pn]);
- goto error_ret;
- }
- indio_dev = iio_allocate_device(sizeof(*st));
- if (indio_dev == NULL) {
- ret = -ENOMEM;
- goto error_ret;
- }
- spi_set_drvdata(spi, indio_dev);
- st = iio_priv(indio_dev);
- mutex_init(&st->lock);
- st->sdev = spi;
- st->sample = pins[0];
- st->rdvel = pins[1];
- indio_dev->dev.parent = &spi->dev;
- indio_dev->info = &ad2s120x_info;
- indio_dev->modes = INDIO_DIRECT_MODE;
- ret = iio_device_register(indio_dev);
- if (ret)
- goto error_free_dev;
- spi->max_speed_hz = AD2S120X_HZ;
- spi->mode = SPI_MODE_3;
- spi_setup(spi);
- return 0;
- error_free_dev:
- iio_free_device(indio_dev);
- error_ret:
- for (--pn; pn >= 0; pn--)
- gpio_free(pins[pn]);
- return ret;
- }
- static int __devexit ad2s120x_remove(struct spi_device *spi)
- {
- iio_device_unregister(spi_get_drvdata(spi));
- return 0;
- }
- static struct spi_driver ad2s120x_driver = {
- .driver = {
- .name = DRV_NAME,
- .owner = THIS_MODULE,
- },
- .probe = ad2s120x_probe,
- .remove = __devexit_p(ad2s120x_remove),
- };
- static __init int ad2s120x_spi_init(void)
- {
- return spi_register_driver(&ad2s120x_driver);
- }
- module_init(ad2s120x_spi_init);
- static __exit void ad2s120x_spi_exit(void)
- {
- spi_unregister_driver(&ad2s120x_driver);
- }
- module_exit(ad2s120x_spi_exit);
- MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>");
- MODULE_DESCRIPTION("Analog Devices AD2S1200/1205 Resolver to Digital SPI driver");
- MODULE_LICENSE("GPL v2");