drivers/iio/dac/stx104.c

   1 /*
   2  * DAC driver for the Apex Embedded Systems STX104
   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 #include <linux/bitops.h>
  15 #include <linux/device.h>
  16 #include <linux/errno.h>
  17 #include <linux/iio/iio.h>
  18 #include <linux/iio/types.h>
  19 #include <linux/io.h>
  20 #include <linux/ioport.h>
  21 #include <linux/isa.h>
  22 #include <linux/module.h>
  23 #include <linux/moduleparam.h>
  24
  25 #define STX104_NUM_CHAN 2
  26
  27 #define STX104_CHAN(chan) {                             \
  28         .type = IIO_VOLTAGE,                            \
  29         .channel = chan,                                \
  30         .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),   \
  31         .indexed = 1,                                   \
  32         .output = 1                                     \
  33 }
  34
  35 #define STX104_EXTENT 16
  36
  37 static unsigned int base[max_num_isa_dev(STX104_EXTENT)];
  38 static unsigned int num_stx104;
  39 module_param_array(base, uint, &num_stx104, 0);
  40 MODULE_PARM_DESC(base, "Apex Embedded Systems STX104 base addresses");
  41
  42 /**
  43  * struct stx104_iio - IIO device private data structure
  44  * @chan_out_states:    channels' output states
  45  * @base:               base port address of the IIO device
  46  */
  47 struct stx104_iio {
  48         unsigned chan_out_states[STX104_NUM_CHAN];
  49         unsigned base;
  50 };
  51
  52 static int stx104_read_raw(struct iio_dev *indio_dev,
  53         struct iio_chan_spec const *chan, int *val, int *val2, long mask)
  54 {
  55         struct stx104_iio *const priv = iio_priv(indio_dev);
  56
  57         if (mask != IIO_CHAN_INFO_RAW)
  58                 return -EINVAL;
  59
  60         *val = priv->chan_out_states[chan->channel];
  61
  62         return IIO_VAL_INT;
  63 }
  64
  65 static int stx104_write_raw(struct iio_dev *indio_dev,
  66         struct iio_chan_spec const *chan, int val, int val2, long mask)
  67 {
  68         struct stx104_iio *const priv = iio_priv(indio_dev);
  69         const unsigned chan_addr_offset = 2 * chan->channel;
  70
  71         if (mask != IIO_CHAN_INFO_RAW)
  72                 return -EINVAL;
  73
  74         priv->chan_out_states[chan->channel] = val;
  75         outw(val, priv->base + 4 + chan_addr_offset);
  76
  77         return 0;
  78 }
  79
  80 static const struct iio_info stx104_info = {
  81         .driver_module = THIS_MODULE,
  82         .read_raw = stx104_read_raw,
  83         .write_raw = stx104_write_raw
  84 };
  85
  86 static const struct iio_chan_spec stx104_channels[STX104_NUM_CHAN] = {
  87         STX104_CHAN(0),
  88         STX104_CHAN(1)
  89 };
  90
  91 static int stx104_probe(struct device *dev, unsigned int id)
  92 {
  93         struct iio_dev *indio_dev;
  94         struct stx104_iio *priv;
  95
  96         indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
  97         if (!indio_dev)
  98                 return -ENOMEM;
  99
 100         if (!devm_request_region(dev, base[id], STX104_EXTENT,
 101                 dev_name(dev))) {
 102                 dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
 103                         base[id], base[id] + STX104_EXTENT);
 104                 return -EBUSY;
 105         }
 106
 107         indio_dev->info = &stx104_info;
 108         indio_dev->modes = INDIO_DIRECT_MODE;
 109         indio_dev->channels = stx104_channels;
 110         indio_dev->num_channels = STX104_NUM_CHAN;
 111         indio_dev->name = dev_name(dev);
 112
 113         priv = iio_priv(indio_dev);
 114         priv->base = base[id];
 115
 116         /* initialize DAC output to 0V */
 117         outw(0, base[id] + 4);
 118         outw(0, base[id] + 6);
 119
 120         return devm_iio_device_register(dev, indio_dev);
 121 }
 122
 123 static struct isa_driver stx104_driver = {
 124         .probe = stx104_probe,
 125         .driver = {
 126                 .name = "stx104"
 127         }
 128 };
 129
 130 module_isa_driver(stx104_driver, num_stx104);
 131
 132 MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
 133 MODULE_DESCRIPTION("Apex Embedded Systems STX104 DAC driver");
 134 MODULE_LICENSE("GPL v2");