release/src-rt-6.x/linux/linux-2.6/drivers/s390/cio/airq.c

   1 /*
   2  *  drivers/s390/cio/airq.c
   3  *   S/390 common I/O routines -- support for adapter interruptions
   4  *
   5  *    Copyright (C) 1999-2002 IBM Deutschland Entwicklung GmbH,
   6  *                            IBM Corporation
   7  *    Author(s): Ingo Adlung (adlung@de.ibm.com)
   8  *               Cornelia Huck (cornelia.huck@de.ibm.com)
   9  *               Arnd Bergmann (arndb@de.ibm.com)
  10  */
  11
  12 #include <linux/init.h>
  13 #include <linux/module.h>
  14 #include <linux/slab.h>
  15 #include <linux/rcupdate.h>
  16
  17 #include "cio_debug.h"
  18 #include "airq.h"
  19
  20 static adapter_int_handler_t adapter_handler;
  21
  22 /*
  23  * register for adapter interrupts
  24  *
  25  * With HiperSockets the zSeries architecture provides for
  26  *  means of adapter interrups, pseudo I/O interrupts that are
  27  *  not tied to an I/O subchannel, but to an adapter. However,
  28  *  it doesn't disclose the info how to enable/disable them, but
  29  *  to recognize them only. Perhaps we should consider them
  30  *  being shared interrupts, and thus build a linked list
  31  *  of adapter handlers ... to be evaluated ...
  32  */
  33 int
  34 s390_register_adapter_interrupt (adapter_int_handler_t handler)
  35 {
  36         int ret;
  37         char dbf_txt[15];
  38
  39         CIO_TRACE_EVENT (4, "rgaint");
  40
  41         if (handler == NULL)
  42                 ret = -EINVAL;
  43         else
  44                 ret = (cmpxchg(&adapter_handler, NULL, handler) ? -EBUSY : 0);
  45         if (!ret)
  46                 synchronize_sched();  /* Allow interrupts to complete. */
  47
  48         sprintf (dbf_txt, "ret:%d", ret);
  49         CIO_TRACE_EVENT (4, dbf_txt);
  50
  51         return ret;
  52 }
  53
  54 int
  55 s390_unregister_adapter_interrupt (adapter_int_handler_t handler)
  56 {
  57         int ret;
  58         char dbf_txt[15];
  59
  60         CIO_TRACE_EVENT (4, "urgaint");
  61
  62         if (handler == NULL)
  63                 ret = -EINVAL;
  64         else {
  65                 adapter_handler = NULL;
  66                 synchronize_sched();  /* Allow interrupts to complete. */
  67                 ret = 0;
  68         }
  69         sprintf (dbf_txt, "ret:%d", ret);
  70         CIO_TRACE_EVENT (4, dbf_txt);
  71
  72         return ret;
  73 }
  74
  75 void
  76 do_adapter_IO (void)
  77 {
  78         CIO_TRACE_EVENT (6, "doaio");
  79
  80         if (adapter_handler)
  81                 (*adapter_handler) ();
  82 }
  83
  84 EXPORT_SYMBOL (s390_register_adapter_interrupt);
  85 EXPORT_SYMBOL (s390_unregister_adapter_interrupt);