drivers/iio/dac/cio-dac.c

   1 /*
   2  * IIO driver for the Measurement Computing CIO-DAC
   3  * Copyright (C) 2016 William Breathitt Gray
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License, version 2, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * This driver supports the following Measurement Computing devices: CIO-DAC16,
  15  * CIO-DAC06, and PC104-DAC06.
  16  */
  17 #include <linux/bitops.h>
  18 #include <linux/device.h>
  19 #include <linux/errno.h>
  20 #include <linux/iio/iio.h>
  21 #include <linux/iio/types.h>
  22 #include <linux/io.h>
  23 #include <linux/ioport.h>
  24 #include <linux/isa.h>
  25 #include <linux/module.h>
  26 #include <linux/moduleparam.h>
  27
  28 #define CIO_DAC_NUM_CHAN 16
  29
  30 #define CIO_DAC_CHAN(chan) {                            \
  31         .type = IIO_VOLTAGE,                            \
  32         .channel = chan,                                \
  33         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),   \
  34         .indexed = 1,                                   \
  35         .output = 1                                     \
  36 }
  37
  38 #define CIO_DAC_EXTENT 32
  39
  40 static unsigned int base[max_num_isa_dev(CIO_DAC_EXTENT)];
  41 static unsigned int num_cio_dac;
  42 module_param_array(base, uint, &num_cio_dac, 0);
  43 MODULE_PARM_DESC(base, "Measurement Computing CIO-DAC base addresses");
  44
  45 /**
  46  * struct cio_dac_iio - IIO device private data structure
  47  * @chan_out_states:    channels' output states
  48  * @base:               base port address of the IIO device
  49  */
  50 struct cio_dac_iio {
  51         int chan_out_states[CIO_DAC_NUM_CHAN];
  52         unsigned int base;
  53 };
  54
  55 static int cio_dac_read_raw(struct iio_dev *indio_dev,
  56         struct iio_chan_spec const *chan, int *val, int *val2, long mask)
  57 {
  58         struct cio_dac_iio *const priv = iio_priv(indio_dev);
  59
  60         if (mask != IIO_CHAN_INFO_RAW)
  61                 return -EINVAL;
  62
  63         *val = priv->chan_out_states[chan->channel];
  64
  65         return IIO_VAL_INT;
  66 }
  67
  68 static int cio_dac_write_raw(struct iio_dev *indio_dev,
  69         struct iio_chan_spec const *chan, int val, int val2, long mask)
  70 {
  71         struct cio_dac_iio *const priv = iio_priv(indio_dev);
  72         const unsigned int chan_addr_offset = 2 * chan->channel;
  73
  74         if (mask != IIO_CHAN_INFO_RAW)
  75                 return -EINVAL;
  76
  77         /* DAC can only accept up to a 16-bit value */
  78         if ((unsigned int)val > 65535)
  79                 return -EINVAL;
  80
  81         priv->chan_out_states[chan->channel] = val;
  82         outw(val, priv->base + chan_addr_offset);
  83
  84         return 0;
  85 }
  86
  87 static const struct iio_info cio_dac_info = {
  88         .driver_module = THIS_MODULE,
  89         .read_raw = cio_dac_read_raw,
  90         .write_raw = cio_dac_write_raw
  91 };
  92
  93 static const struct iio_chan_spec cio_dac_channels[CIO_DAC_NUM_CHAN] = {
  94         CIO_DAC_CHAN(0), CIO_DAC_CHAN(1), CIO_DAC_CHAN(2), CIO_DAC_CHAN(3),
  95         CIO_DAC_CHAN(4), CIO_DAC_CHAN(5), CIO_DAC_CHAN(6), CIO_DAC_CHAN(7),
  96         CIO_DAC_CHAN(8), CIO_DAC_CHAN(9), CIO_DAC_CHAN(10), CIO_DAC_CHAN(11),
  97         CIO_DAC_CHAN(12), CIO_DAC_CHAN(13), CIO_DAC_CHAN(14), CIO_DAC_CHAN(15)
  98 };
  99
 100 static int cio_dac_probe(struct device *dev, unsigned int id)
 101 {
 102         struct iio_dev *indio_dev;
 103         struct cio_dac_iio *priv;
 104         unsigned int i;
 105
 106         indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
 107         if (!indio_dev)
 108                 return -ENOMEM;
 109
 110         if (!devm_request_region(dev, base[id], CIO_DAC_EXTENT,
 111                 dev_name(dev))) {
 112                 dev_err(dev, "Unable to request port addresses (0x%X-0x%X)\n",
 113                         base[id], base[id] + CIO_DAC_EXTENT);
 114                 return -EBUSY;
 115         }
 116
 117         indio_dev->info = &cio_dac_info;
 118         indio_dev->modes = INDIO_DIRECT_MODE;
 119         indio_dev->channels = cio_dac_channels;
 120         indio_dev->num_channels = CIO_DAC_NUM_CHAN;
 121         indio_dev->name = dev_name(dev);
 122
 123         priv = iio_priv(indio_dev);
 124         priv->base = base[id];
 125
 126         /* initialize DAC outputs to 0V */
 127         for (i = 0; i < 32; i += 2)
 128                 outw(0, base[id] + i);
 129
 130         return devm_iio_device_register(dev, indio_dev);
 131 }
 132
 133 static struct isa_driver cio_dac_driver = {
 134         .probe = cio_dac_probe,
 135         .driver = {
 136                 .name = "cio-dac"
 137         }
 138 };
 139
 140 module_isa_driver(cio_dac_driver, num_cio_dac);
 141
 142 MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
 143 MODULE_DESCRIPTION("Measurement Computing CIO-DAC IIO driver");
 144 MODULE_LICENSE("GPL v2");