drivers/staging/iio/resolver/ad2s120x.c

   1 /*
   2  * ad2s120x.c simple support for the ADI Resolver to Digital Converters: AD2S1200/1205
   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 #include <linux/delay.h>
  18 #include <linux/gpio.h>
  19
  20 #include "../iio.h"
  21 #include "../sysfs.h"
  22
  23 #define DRV_NAME "ad2s120x"
  24
  25 /* input pin sample and rdvel is controlled by driver */
  26 #define AD2S120X_PN     2
  27
  28 /* input clock on serial interface */
  29 #define AD2S120X_HZ     8192000
  30 /* clock period in nano second */
  31 #define AD2S120X_TSCLK  (1000000000/AD2S120X_HZ)
  32
  33 struct ad2s120x_state {
  34         struct mutex lock;
  35         struct spi_device *sdev;
  36         int sample;
  37         int rdvel;
  38         u8 rx[2] ____cacheline_aligned;
  39 };
  40
  41 static ssize_t ad2s120x_show_val(struct device *dev,
  42                         struct device_attribute *attr, char *buf)
  43 {
  44         int ret = 0;
  45         ssize_t len = 0;
  46         u16 pos;
  47         s16 vel;
  48         u8 status;
  49         struct ad2s120x_state *st = iio_priv(dev_get_drvdata(dev));
  50         struct iio_dev_attr *iattr = to_iio_dev_attr(attr);
  51
  52         mutex_lock(&st->lock);
  53
  54         gpio_set_value(st->sample, 0);
  55         /* delay (6 * AD2S120X_TSCLK + 20) nano seconds */
  56         udelay(1);
  57         gpio_set_value(st->sample, 1);
  58         gpio_set_value(st->rdvel, iattr->address);
  59         ret = spi_read(st->sdev, st->rx, 2);
  60         if (ret < 0)
  61                 goto error_ret;
  62         status = st->rx[1];
  63         if (iattr->address)
  64                 pos = (((u16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
  65         else {
  66                 vel = (st->rx[0] & 0x80) ? 0xf000 : 0;
  67                 vel |= (((s16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4);
  68         }
  69         len = sprintf(buf, "%d %c%c%c%c ", iattr->address ? pos : vel,
  70                                 (status & 0x8) ? 'P' : 'V',
  71                                 (status & 0x4) ? 'd' : '_',
  72                                 (status & 0x2) ? 'l' : '_',
  73                                 (status & 0x1) ? '1' : '0');
  74 error_ret:
  75         /* delay (2 * AD2S120X_TSCLK + 20) ns for sample pulse */
  76         udelay(1);
  77         mutex_unlock(&st->lock);
  78
  79         return ret ? ret : len;
  80 }
  81
  82 static IIO_DEVICE_ATTR(pos, S_IRUGO, ad2s120x_show_val, NULL, 1);
  83 static IIO_DEVICE_ATTR(vel, S_IRUGO, ad2s120x_show_val, NULL, 0);
  84
  85 static struct attribute *ad2s120x_attributes[] = {
  86         &iio_dev_attr_pos.dev_attr.attr,
  87         &iio_dev_attr_vel.dev_attr.attr,
  88         NULL,
  89 };
  90
  91 static const struct attribute_group ad2s120x_attribute_group = {
  92         .attrs = ad2s120x_attributes,
  93 };
  94
  95 static const struct iio_info ad2s120x_info = {
  96         .attrs = &ad2s120x_attribute_group,
  97         .driver_module = THIS_MODULE,
  98 };
  99
 100 static int __devinit ad2s120x_probe(struct spi_device *spi)
 101 {
 102         struct ad2s120x_state *st;
 103         struct iio_dev *indio_dev;
 104         int pn, ret = 0;
 105         unsigned short *pins = spi->dev.platform_data;
 106
 107         for (pn = 0; pn < AD2S120X_PN; pn++)
 108                 if (gpio_request_one(pins[pn], GPIOF_DIR_OUT, DRV_NAME)) {
 109                         pr_err("%s: request gpio pin %d failed\n",
 110                                                 DRV_NAME, pins[pn]);
 111                         goto error_ret;
 112                 }
 113         indio_dev = iio_allocate_device(sizeof(*st));
 114         if (indio_dev == NULL) {
 115                 ret = -ENOMEM;
 116                 goto error_ret;
 117         }
 118         spi_set_drvdata(spi, indio_dev);
 119         st = iio_priv(indio_dev);
 120         mutex_init(&st->lock);
 121         st->sdev = spi;
 122         st->sample = pins[0];
 123         st->rdvel = pins[1];
 124
 125         indio_dev->dev.parent = &spi->dev;
 126         indio_dev->info = &ad2s120x_info;
 127         indio_dev->modes = INDIO_DIRECT_MODE;
 128
 129         ret = iio_device_register(indio_dev);
 130         if (ret)
 131                 goto error_free_dev;
 132
 133         spi->max_speed_hz = AD2S120X_HZ;
 134         spi->mode = SPI_MODE_3;
 135         spi_setup(spi);
 136
 137         return 0;
 138
 139 error_free_dev:
 140         iio_free_device(indio_dev);
 141 error_ret:
 142         for (--pn; pn >= 0; pn--)
 143                 gpio_free(pins[pn]);
 144         return ret;
 145 }
 146
 147 static int __devexit ad2s120x_remove(struct spi_device *spi)
 148 {
 149         iio_device_unregister(spi_get_drvdata(spi));
 150
 151         return 0;
 152 }
 153
 154 static struct spi_driver ad2s120x_driver = {
 155         .driver = {
 156                 .name = DRV_NAME,
 157                 .owner = THIS_MODULE,
 158         },
 159         .probe = ad2s120x_probe,
 160         .remove = __devexit_p(ad2s120x_remove),
 161 };
 162
 163 static __init int ad2s120x_spi_init(void)
 164 {
 165         return spi_register_driver(&ad2s120x_driver);
 166 }
 167 module_init(ad2s120x_spi_init);
 168
 169 static __exit void ad2s120x_spi_exit(void)
 170 {
 171         spi_unregister_driver(&ad2s120x_driver);
 172 }
 173 module_exit(ad2s120x_spi_exit);
 174
 175 MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>");
 176 MODULE_DESCRIPTION("Analog Devices AD2S1200/1205 Resolver to Digital SPI driver");
 177 MODULE_LICENSE("GPL v2");