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     You should have received a copy of the GNU General Public License
  19     along with this program; if not, write to the Free Software
  20     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21 */
  22 /*
  23 Driver: pcmda12
  24 Description: A driver for the Winsystems PCM-D/A-12
  25 Devices: [Winsystems] PCM-D/A-12 (pcmda12)
  26 Author: Calin Culianu <calin@ajvar.org>
  27 Updated: Fri, 13 Jan 2006 12:01:01 -0500
  28 Status: works
  29
  30 A driver for the relatively straightforward-to-program PCM-D/A-12.
  31 This board doesn't support commands, and the only way to set its
  32 analog output range is to jumper the board.  As such,
  33 comedi_data_write() ignores the range value specified.
  34
  35 The board uses 16 consecutive I/O addresses starting at the I/O port
  36 base address.  Each address corresponds to the LSB then MSB of a
  37 particular channel from 0-7.
  38
  39 Note that the board is not ISA-PNP capable and thus
  40 needs the I/O port comedi_config parameter.
  41
  42 Note that passing a nonzero value as the second config option will
  43 enable "simultaneous xfer" mode for this board, in which AO writes
  44 will not take effect until a subsequent read of any AO channel.  This
  45 is so that one can speed up programming by preloading all AO registers
  46 with values before simultaneously setting them to take effect with one
  47 read command.
  48
  49 Configuration Options:
  50   [0] - I/O port base address
  51   [1] - Do Simultaneous Xfer (see description)
  52 */
  53
  54 #include "../comedidev.h"
  55
  56 #define CHANS 8
  57 #define IOSIZE 16
  58 #define LSB(x) ((unsigned char)((x) & 0xff))
  59 #define MSB(x) ((unsigned char)((((unsigned short)(x))>>8) & 0xff))
  60 #define LSB_PORT(chan) (dev->iobase + (chan)*2)
  61 #define MSB_PORT(chan) (LSB_PORT(chan)+1)
  62 #define BITS 12
  63
  64 /* note these have no effect and are merely here for reference..
  65    these are configured by jumpering the board! */
  66 static const struct comedi_lrange pcmda12_ranges = {
  67         3,
  68         {
  69          UNI_RANGE(5), UNI_RANGE(10), BIP_RANGE(5)
  70          }
  71 };
  72
  73 struct pcmda12_private {
  74
  75         unsigned int ao_readback[CHANS];
  76         int simultaneous_xfer_mode;
  77 };
  78
  79 static void zero_chans(struct comedi_device *dev)
  80 {                               /* sets up an
  81                                    ASIC chip to defaults */
  82         int i;
  83         for (i = 0; i < CHANS; ++i) {
  84 /*      /\* do this as one instruction?? *\/ */
  85 /*      outw(0, LSB_PORT(chan)); */
  86                 outb(0, LSB_PORT(i));
  87                 outb(0, MSB_PORT(i));
  88         }
  89         inb(LSB_PORT(0));       /* update chans. */
  90 }
  91
  92 static int ao_winsn(struct comedi_device *dev, struct comedi_subdevice *s,
  93                     struct comedi_insn *insn, unsigned int *data)
  94 {
  95         struct pcmda12_private *devpriv = dev->private;
  96         int i;
  97         int chan = CR_CHAN(insn->chanspec);
  98
  99         /* Writing a list of values to an AO channel is probably not
 100          * very useful, but that's how the interface is defined. */
 101         for (i = 0; i < insn->n; ++i) {
 102
 103 /*      /\* do this as one instruction?? *\/ */
 104 /*      outw(data[i], LSB_PORT(chan)); */
 105
 106                 /* Need to do this as two instructions due to 8-bit bus?? */
 107                 /*  first, load the low byte */
 108                 outb(LSB(data[i]), LSB_PORT(chan));
 109                 /*  next, write the high byte */
 110                 outb(MSB(data[i]), MSB_PORT(chan));
 111
 112                 /* save shadow register */
 113                 devpriv->ao_readback[chan] = data[i];
 114
 115                 if (!devpriv->simultaneous_xfer_mode)
 116                         inb(LSB_PORT(chan));
 117         }
 118
 119         /* return the number of samples written */
 120         return i;
 121 }
 122
 123 /* AO subdevices should have a read insn as well as a write insn.
 124
 125    Usually this means copying a value stored in devpriv->ao_readback.
 126    However, since this driver supports simultaneous xfer then sometimes
 127    this function actually accomplishes work.
 128
 129    Simultaneaous xfer mode is accomplished by loading ALL the values
 130    you want for AO in all the channels, then READing off one of the AO
 131    registers to initiate the instantaneous simultaneous update of all
 132    DAC outputs, which makes all AO channels update simultaneously.
 133    This is useful for some control applications, I would imagine.
 134 */
 135 static int ao_rinsn(struct comedi_device *dev, struct comedi_subdevice *s,
 136                     struct comedi_insn *insn, unsigned int *data)
 137 {
 138         struct pcmda12_private *devpriv = dev->private;
 139         int i;
 140         int chan = CR_CHAN(insn->chanspec);
 141
 142         for (i = 0; i < insn->n; i++) {
 143                 if (devpriv->simultaneous_xfer_mode)
 144                         inb(LSB_PORT(chan));
 145                 /* read back shadow register */
 146                 data[i] = devpriv->ao_readback[chan];
 147         }
 148
 149         return i;
 150 }
 151
 152 static int pcmda12_attach(struct comedi_device *dev,
 153                           struct comedi_devconfig *it)
 154 {
 155         struct pcmda12_private *devpriv;
 156         struct comedi_subdevice *s;
 157         int ret;
 158
 159         ret = comedi_request_region(dev, it->options[0], IOSIZE);
 160         if (ret)
 161                 return ret;
 162
 163         devpriv = kzalloc(sizeof(*devpriv), GFP_KERNEL);
 164         if (!devpriv)
 165                 return -ENOMEM;
 166         dev->private = devpriv;
 167
 168         devpriv->simultaneous_xfer_mode = it->options[1];
 169
 170         ret = comedi_alloc_subdevices(dev, 1);
 171         if (ret)
 172                 return ret;
 173
 174         s = &dev->subdevices[0];
 175         s->private = NULL;
 176         s->maxdata = (0x1 << BITS) - 1;
 177         s->range_table = &pcmda12_ranges;
 178         s->type = COMEDI_SUBD_AO;
 179         s->subdev_flags = SDF_READABLE | SDF_WRITABLE;
 180         s->n_chan = CHANS;
 181         s->insn_write = &ao_winsn;
 182         s->insn_read = &ao_rinsn;
 183
 184         zero_chans(dev);        /* clear out all the registers, basically */
 185
 186         return 1;
 187 }
 188
 189 static struct comedi_driver pcmda12_driver = {
 190         .driver_name    = "pcmda12",
 191         .module         = THIS_MODULE,
 192         .attach         = pcmda12_attach,
 193         .detach         = comedi_legacy_detach,
 194 };
 195 module_comedi_driver(pcmda12_driver);
 196
 197 MODULE_AUTHOR("Comedi http://www.comedi.org");
 198 MODULE_DESCRIPTION("Comedi low-level driver");
 199 MODULE_LICENSE("GPL");