drivers/staging/comedi/drivers/8255.c

   1 /*
   2  * comedi/drivers/8255.c
   3  * Driver for 8255
   4  *
   5  * COMEDI - Linux Control and Measurement Device Interface
   6  * Copyright (C) 1998 David A. Schleef <ds@schleef.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 /*
  20  * Driver: 8255
  21  * Description: generic 8255 support
  22  * Devices: [standard] 8255 (8255)
  23  * Author: ds
  24  * Status: works
  25  * Updated: Fri,  7 Jun 2002 12:56:45 -0700
  26  *
  27  * The classic in digital I/O.  The 8255 appears in Comedi as a single
  28  * digital I/O subdevice with 24 channels.  The channel 0 corresponds
  29  * to the 8255's port A, bit 0; channel 23 corresponds to port C, bit
  30  * 7.  Direction configuration is done in blocks, with channels 0-7,
  31  * 8-15, 16-19, and 20-23 making up the 4 blocks.  The only 8255 mode
  32  * supported is mode 0.
  33  *
  34  * You should enable compilation this driver if you plan to use a board
  35  * that has an 8255 chip.  For multifunction boards, the main driver will
  36  * configure the 8255 subdevice automatically.
  37  *
  38  * This driver also works independently with ISA and PCI cards that
  39  * directly map the 8255 registers to I/O ports, including cards with
  40  * multiple 8255 chips.  To configure the driver for such a card, the
  41  * option list should be a list of the I/O port bases for each of the
  42  * 8255 chips.  For example,
  43  *
  44  *   comedi_config /dev/comedi0 8255 0x200,0x204,0x208,0x20c
  45  *
  46  * Note that most PCI 8255 boards do NOT work with this driver, and
  47  * need a separate driver as a wrapper.  For those that do work, the
  48  * I/O port base address can be found in the output of 'lspci -v'.
  49  */
  50
  51 #include <linux/module.h>
  52 #include "../comedidev.h"
  53
  54 #include "8255.h"
  55
  56 static int dev_8255_attach(struct comedi_device *dev,
  57                            struct comedi_devconfig *it)
  58 {
  59         struct comedi_subdevice *s;
  60         unsigned long iobase;
  61         int ret;
  62         int i;
  63
  64         for (i = 0; i < COMEDI_NDEVCONFOPTS; i++) {
  65                 iobase = it->options[i];
  66                 if (!iobase)
  67                         break;
  68         }
  69         if (i == 0) {
  70                 dev_warn(dev->class_dev, "no devices specified\n");
  71                 return -EINVAL;
  72         }
  73
  74         ret = comedi_alloc_subdevices(dev, i);
  75         if (ret)
  76                 return ret;
  77
  78         for (i = 0; i < dev->n_subdevices; i++) {
  79                 s = &dev->subdevices[i];
  80                 iobase = it->options[i];
  81
  82                 /*
  83                  * __comedi_request_region() does not set dev->iobase.
  84                  *
  85                  * For 8255 devices that are manually attached using
  86                  * comedi_config, the 'iobase' is the actual I/O port
  87                  * base address of the chip.
  88                  */
  89                 ret = __comedi_request_region(dev, iobase, I8255_SIZE);
  90                 if (ret) {
  91                         s->type = COMEDI_SUBD_UNUSED;
  92                 } else {
  93                         ret = subdev_8255_init(dev, s, NULL, iobase);
  94                         if (ret) {
  95                                 /*
  96                                  * Release the I/O port region here, as the
  97                                  * "detach" handler cannot find it.
  98                                  */
  99                                 release_region(iobase, I8255_SIZE);
 100                                 s->type = COMEDI_SUBD_UNUSED;
 101                                 return ret;
 102                         }
 103                 }
 104         }
 105
 106         return 0;
 107 }
 108
 109 static void dev_8255_detach(struct comedi_device *dev)
 110 {
 111         struct comedi_subdevice *s;
 112         int i;
 113
 114         for (i = 0; i < dev->n_subdevices; i++) {
 115                 s = &dev->subdevices[i];
 116                 if (s->type != COMEDI_SUBD_UNUSED) {
 117                         unsigned long regbase = subdev_8255_regbase(s);
 118
 119                         release_region(regbase, I8255_SIZE);
 120                 }
 121         }
 122 }
 123
 124 static struct comedi_driver dev_8255_driver = {
 125         .driver_name    = "8255",
 126         .module         = THIS_MODULE,
 127         .attach         = dev_8255_attach,
 128         .detach         = dev_8255_detach,
 129 };
 130 module_comedi_driver(dev_8255_driver);
 131
 132 MODULE_AUTHOR("Comedi http://www.comedi.org");
 133 MODULE_DESCRIPTION("Comedi driver for standalone 8255 devices");
 134 MODULE_LICENSE("GPL");