drivers/staging/comedi/drivers/pcmda12.c

   1 /*
   2     comedi/drivers/pcmda12.c
   3     Driver for Winsystems PC-104 based PCM-D/A-12 8-channel AO board.
   4
   5     COMEDI - Linux Control and Measurement Device Interface
   6     Copyright (C) 2006 Calin A. Culianu <calin@ajvar.org>
   7
   8     This program is free software; you can redistribute it and/or modify
   9     it under the terms of the GNU General Public License as published by
  10     the Free Software Foundation; either version 2 of the License, or
  11     (at your option) any later version.
  12
  13     This program is distributed in the hope that it will be useful,
  14     but WITHOUT ANY WARRANTY; without even the implied warranty of
  15     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16     GNU General Public License for more details.
  17 */
  18 /*
  19 Driver: pcmda12
  20 Description: A driver for the Winsystems PCM-D/A-12
  21 Devices: [Winsystems] PCM-D/A-12 (pcmda12)
  22 Author: Calin Culianu <calin@ajvar.org>
  23 Updated: Fri, 13 Jan 2006 12:01:01 -0500
  24 Status: works
  25
  26 A driver for the relatively straightforward-to-program PCM-D/A-12.
  27 This board doesn't support commands, and the only way to set its
  28 analog output range is to jumper the board.  As such,
  29 comedi_data_write() ignores the range value specified.
  30
  31 The board uses 16 consecutive I/O addresses starting at the I/O port
  32 base address.  Each address corresponds to the LSB then MSB of a
  33 particular channel from 0-7.
  34
  35 Note that the board is not ISA-PNP capable and thus
  36 needs the I/O port comedi_config parameter.
  37
  38 Note that passing a nonzero value as the second config option will
  39 enable "simultaneous xfer" mode for this board, in which AO writes
  40 will not take effect until a subsequent read of any AO channel.  This
  41 is so that one can speed up programming by preloading all AO registers
  42 with values before simultaneously setting them to take effect with one
  43 read command.
  44
  45 Configuration Options:
  46   [0] - I/O port base address
  47   [1] - Do Simultaneous Xfer (see description)
  48 */
  49
  50 #include "../comedidev.h"
  51
  52 #define CHANS 8
  53 #define IOSIZE 16
  54 #define LSB(x) ((unsigned char)((x) & 0xff))
  55 #define MSB(x) ((unsigned char)((((unsigned short)(x))>>8) & 0xff))
  56 #define LSB_PORT(chan) (dev->iobase + (chan)*2)
  57 #define MSB_PORT(chan) (LSB_PORT(chan)+1)
  58 #define BITS 12
  59
  60 /* note these have no effect and are merely here for reference..
  61    these are configured by jumpering the board! */
  62 static const struct comedi_lrange pcmda12_ranges = {
  63         3,
  64         {
  65          UNI_RANGE(5), UNI_RANGE(10), BIP_RANGE(5)
  66          }
  67 };
  68
  69 struct pcmda12_private {
  70
  71         unsigned int ao_readback[CHANS];
  72         int simultaneous_xfer_mode;
  73 };
  74
  75 static void zero_chans(struct comedi_device *dev)
  76 {                               /* sets up an
  77                                    ASIC chip to defaults */
  78         int i;
  79         for (i = 0; i < CHANS; ++i) {
  80 /*      /\* do this as one instruction?? *\/ */
  81 /*      outw(0, LSB_PORT(chan)); */
  82                 outb(0, LSB_PORT(i));
  83                 outb(0, MSB_PORT(i));
  84         }
  85         inb(LSB_PORT(0));       /* update chans. */
  86 }
  87
  88 static int ao_winsn(struct comedi_device *dev, struct comedi_subdevice *s,
  89                     struct comedi_insn *insn, unsigned int *data)
  90 {
  91         struct pcmda12_private *devpriv = dev->private;
  92         int i;
  93         int chan = CR_CHAN(insn->chanspec);
  94
  95         /* Writing a list of values to an AO channel is probably not
  96          * very useful, but that's how the interface is defined. */
  97         for (i = 0; i < insn->n; ++i) {
  98
  99 /*      /\* do this as one instruction?? *\/ */
 100 /*      outw(data[i], LSB_PORT(chan)); */
 101
 102                 /* Need to do this as two instructions due to 8-bit bus?? */
 103                 /*  first, load the low byte */
 104                 outb(LSB(data[i]), LSB_PORT(chan));
 105                 /*  next, write the high byte */
 106                 outb(MSB(data[i]), MSB_PORT(chan));
 107
 108                 /* save shadow register */
 109                 devpriv->ao_readback[chan] = data[i];
 110
 111                 if (!devpriv->simultaneous_xfer_mode)
 112                         inb(LSB_PORT(chan));
 113         }
 114
 115         /* return the number of samples written */
 116         return i;
 117 }
 118
 119 /* AO subdevices should have a read insn as well as a write insn.
 120
 121    Usually this means copying a value stored in devpriv->ao_readback.
 122    However, since this driver supports simultaneous xfer then sometimes
 123    this function actually accomplishes work.
 124
 125    Simultaneaous xfer mode is accomplished by loading ALL the values
 126    you want for AO in all the channels, then READing off one of the AO
 127    registers to initiate the instantaneous simultaneous update of all
 128    DAC outputs, which makes all AO channels update simultaneously.
 129    This is useful for some control applications, I would imagine.
 130 */
 131 static int ao_rinsn(struct comedi_device *dev, struct comedi_subdevice *s,
 132                     struct comedi_insn *insn, unsigned int *data)
 133 {
 134         struct pcmda12_private *devpriv = dev->private;
 135         int i;
 136         int chan = CR_CHAN(insn->chanspec);
 137
 138         for (i = 0; i < insn->n; i++) {
 139                 if (devpriv->simultaneous_xfer_mode)
 140                         inb(LSB_PORT(chan));
 141                 /* read back shadow register */
 142                 data[i] = devpriv->ao_readback[chan];
 143         }
 144
 145         return i;
 146 }
 147
 148 static int pcmda12_attach(struct comedi_device *dev,
 149                           struct comedi_devconfig *it)
 150 {
 151         struct pcmda12_private *devpriv;
 152         struct comedi_subdevice *s;
 153         int ret;
 154
 155         ret = comedi_request_region(dev, it->options[0], IOSIZE);
 156         if (ret)
 157                 return ret;
 158
 159         devpriv = kzalloc(sizeof(*devpriv), GFP_KERNEL);
 160         if (!devpriv)
 161                 return -ENOMEM;
 162         dev->private = devpriv;
 163
 164         devpriv->simultaneous_xfer_mode = it->options[1];
 165
 166         ret = comedi_alloc_subdevices(dev, 1);
 167         if (ret)
 168                 return ret;
 169
 170         s = &dev->subdevices[0];
 171         s->private = NULL;
 172         s->maxdata = (0x1 << BITS) - 1;
 173         s->range_table = &pcmda12_ranges;
 174         s->type = COMEDI_SUBD_AO;
 175         s->subdev_flags = SDF_READABLE | SDF_WRITABLE;
 176         s->n_chan = CHANS;
 177         s->insn_write = &ao_winsn;
 178         s->insn_read = &ao_rinsn;
 179
 180         zero_chans(dev);        /* clear out all the registers, basically */
 181
 182         return 1;
 183 }
 184
 185 static struct comedi_driver pcmda12_driver = {
 186         .driver_name    = "pcmda12",
 187         .module         = THIS_MODULE,
 188         .attach         = pcmda12_attach,
 189         .detach         = comedi_legacy_detach,
 190 };
 191 module_comedi_driver(pcmda12_driver);
 192
 193 MODULE_AUTHOR("Comedi http://www.comedi.org");
 194 MODULE_DESCRIPTION("Comedi low-level driver");
 195 MODULE_LICENSE("GPL");