gnu/dist/gdb6/sim/mips/dv-tx3904cpu.c

   1 /*  This file is part of the program GDB, the GNU debugger.
   2
   3     Copyright (C) 1998 Free Software Foundation, Inc.
   4     Contributed by Cygnus Solutions.
   5
   6     This program is free software; you can redistribute it and/or modify
   7     it under the terms of the GNU General Public License as published by
   8     the Free Software Foundation; either version 2 of the License, or
   9     (at your option) any later version.
  10
  11     This program is distributed in the hope that it will be useful,
  12     but WITHOUT ANY WARRANTY; without even the implied warranty of
  13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14     GNU General Public License for more details.
  15
  16     You should have received a copy of the GNU General Public License
  17     along with this program; if not, write to the Free Software
  18     Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  19
  20     */
  21
  22
  23 #include "sim-main.h"
  24 #include "hw-main.h"
  25
  26 /* DEVICE
  27
  28
  29    tx3904cpu - tx3904 cpu virtual device
  30
  31
  32    DESCRIPTION
  33
  34
  35    Implements the external tx3904 functionality.  This includes the
  36    delivery of of interrupts generated from other devices and the
  37    handling of device specific registers.
  38
  39
  40    PROPERTIES
  41
  42    none
  43
  44
  45    PORTS
  46
  47
  48    reset (input)
  49
  50    Currently ignored.
  51
  52
  53    nmi (input)
  54
  55    Deliver a non-maskable interrupt to the processor.
  56
  57
  58    level (input)
  59
  60    Deliver a maskable interrupt of given level, corresponding to
  61    IP[5:0], to processor.
  62
  63
  64
  65    BUGS
  66
  67
  68    When delivering an interrupt, this code assumes that there is only
  69    one processor (number 0).
  70
  71    This code does not attempt to be efficient at handling pending
  72    interrupts.  It simply schedules the interrupt delivery handler
  73    every instruction cycle until all pending interrupts go away.  An
  74    alternative implementation might modify instructions that change
  75    the PSW and have them check to see if the change makes an interrupt
  76    delivery possible.
  77
  78    */
  79
  80
  81
  82 struct tx3904cpu {
  83   /* Pending interrupts for delivery by event handler */
  84   int pending_reset, pending_nmi, pending_level;
  85   struct hw_event* event;
  86 };
  87
  88
  89
  90 /* input port ID's */
  91
  92 enum {
  93   RESET_PORT,
  94   NMI_PORT,
  95   LEVEL_PORT,
  96 };
  97
  98
  99 static const struct hw_port_descriptor tx3904cpu_ports[] = {
 100
 101   /* interrupt inputs */
 102   { "reset", RESET_PORT, 0, input_port, },
 103   { "nmi", NMI_PORT, 0, input_port, },
 104   { "level", LEVEL_PORT, 0, input_port, },
 105
 106   { NULL, },
 107 };
 108
 109
 110 /* Finish off the partially created hw device.  Attach our local
 111    callbacks.  Wire up our port names etc */
 112
 113 static hw_port_event_method tx3904cpu_port_event;
 114
 115
 116
 117 static void
 118 tx3904cpu_finish (struct hw *me)
 119 {
 120   struct tx3904cpu *controller;
 121
 122   controller = HW_ZALLOC (me, struct tx3904cpu);
 123   set_hw_data (me, controller);
 124   set_hw_ports (me, tx3904cpu_ports);
 125   set_hw_port_event (me, tx3904cpu_port_event);
 126
 127   /* Initialize the pending interrupt flags */
 128   controller->pending_level = 0;
 129   controller->pending_reset = 0;
 130   controller->pending_nmi = 0;
 131   controller->event = NULL;
 132 }
 133
 134
 135
 136 /* An event arrives on an interrupt port */
 137
 138 static void
 139 deliver_tx3904cpu_interrupt (struct hw *me,
 140                             void *data)
 141 {
 142   struct tx3904cpu *controller = hw_data (me);
 143   SIM_DESC sd = hw_system (me);
 144   sim_cpu *cpu = STATE_CPU (sd, 0); /* NB: fix CPU 0. */
 145   address_word cia = CIA_GET (cpu);
 146
 147 #define CPU cpu
 148 #define SD current_state
 149
 150   if (controller->pending_reset)
 151     {
 152       controller->pending_reset = 0;
 153       HW_TRACE ((me, "reset pc=0x%08lx", (long) CIA_GET (cpu)));
 154       SignalExceptionNMIReset();
 155     }
 156   else if (controller->pending_nmi)
 157     {
 158       controller->pending_nmi = 0;
 159       HW_TRACE ((me, "nmi pc=0x%08lx", (long) CIA_GET (cpu)));
 160       SignalExceptionNMIReset();
 161     }
 162   else if (controller->pending_level)
 163     {
 164       HW_TRACE ((me, "interrupt level=%d pc=0x%08lx sr=0x%08lx",
 165                  controller->pending_level,
 166                  (long) CIA_GET (cpu), (long) SR));
 167
 168       /* Clear CAUSE register.  It may stay this way if the interrupt
 169          was cleared with a negative pending_level. */
 170       CAUSE &= ~ (cause_IP_mask << cause_IP_shift);
 171
 172       if(controller->pending_level > 0) /* interrupt set */
 173         {
 174           /* set hardware-interrupt subfields of CAUSE register */
 175           CAUSE |= (controller->pending_level & cause_IP_mask) << cause_IP_shift;
 176
 177           /* check for enabled / unmasked interrupts */
 178           if((SR & status_IEc) &&
 179              (controller->pending_level & ((SR >> status_IM_shift) & status_IM_mask)))
 180             {
 181               controller->pending_level = 0;
 182               SignalExceptionInterrupt(0 /* dummy value */);
 183             }
 184           else
 185             {
 186               /* reschedule soon */
 187               if(controller->event != NULL)
 188                 hw_event_queue_deschedule(me, controller->event);
 189               controller->event =
 190                 hw_event_queue_schedule (me, 1, deliver_tx3904cpu_interrupt, NULL);
 191             }
 192         } /* interrupt set */
 193     }
 194 #undef CPU cpu
 195 #undef SD current_state
 196 }
 197
 198
 199 static void
 200 tx3904cpu_port_event (struct hw *me,
 201                      int my_port,
 202                      struct hw *source,
 203                      int source_port,
 204                      int level)
 205 {
 206   struct tx3904cpu *controller = hw_data (me);
 207
 208   switch (my_port)
 209     {
 210     case RESET_PORT:
 211       controller->pending_reset = 1;
 212       HW_TRACE ((me, "port-in reset"));
 213       break;
 214
 215     case NMI_PORT:
 216       controller->pending_nmi = 1;
 217       HW_TRACE ((me, "port-in nmi"));
 218       break;
 219
 220     case LEVEL_PORT:
 221       /* level == 0 means that the interrupt was cleared */
 222       if(level == 0)
 223         controller->pending_level = -1; /* signal end of interrupt */
 224       else
 225         controller->pending_level = level;
 226       HW_TRACE ((me, "port-in level=%d", level));
 227       break;
 228
 229     default:
 230       hw_abort (me, "bad switch");
 231       break;
 232     }
 233
 234   /* Schedule an event to be delivered immediately after current
 235      instruction. */
 236   if(controller->event != NULL)
 237     hw_event_queue_deschedule(me, controller->event);
 238   controller->event =
 239     hw_event_queue_schedule (me, 0, deliver_tx3904cpu_interrupt, NULL);
 240 }
 241
 242
 243 const struct hw_descriptor dv_tx3904cpu_descriptor[] = {
 244   { "tx3904cpu", tx3904cpu_finish, },
 245   { NULL },
 246 };