sim/mips/dv-tx3904cpu.c

   1 /*  This file is part of the program GDB, the GNU debugger.
   2
   3     Copyright (C) 1998-2018 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 3 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, see <http://www.gnu.org/licenses/>.
  18
  19     */
  20
  21
  22 #include "sim-main.h"
  23 #include "hw-main.h"
  24
  25 /* DEVICE
  26
  27
  28    tx3904cpu - tx3904 cpu virtual device
  29
  30
  31    DESCRIPTION
  32
  33
  34    Implements the external tx3904 functionality.  This includes the
  35    delivery of of interrupts generated from other devices and the
  36    handling of device specific registers.
  37
  38
  39    PROPERTIES
  40
  41    none
  42
  43
  44    PORTS
  45
  46
  47    reset (input)
  48
  49    Currently ignored.
  50
  51
  52    nmi (input)
  53
  54    Deliver a non-maskable interrupt to the processor.
  55
  56
  57    level (input)
  58
  59    Deliver a maskable interrupt of given level, corresponding to
  60    IP[5:0], to processor.
  61
  62
  63
  64    BUGS
  65
  66
  67    When delivering an interrupt, this code assumes that there is only
  68    one processor (number 0).
  69
  70    This code does not attempt to be efficient at handling pending
  71    interrupts.  It simply schedules the interrupt delivery handler
  72    every instruction cycle until all pending interrupts go away.  An
  73    alternative implementation might modify instructions that change
  74    the PSW and have them check to see if the change makes an interrupt
  75    delivery possible.
  76
  77    */
  78
  79
  80
  81 struct tx3904cpu {
  82   /* Pending interrupts for delivery by event handler */
  83   int pending_reset, pending_nmi, pending_level;
  84   struct hw_event* event;
  85 };
  86
  87
  88
  89 /* input port ID's */
  90
  91 enum {
  92   RESET_PORT,
  93   NMI_PORT,
  94   LEVEL_PORT,
  95 };
  96
  97
  98 static const struct hw_port_descriptor tx3904cpu_ports[] = {
  99
 100   /* interrupt inputs */
 101   { "reset", RESET_PORT, 0, input_port, },
 102   { "nmi", NMI_PORT, 0, input_port, },
 103   { "level", LEVEL_PORT, 0, input_port, },
 104
 105   { NULL, },
 106 };
 107
 108
 109 /* Finish off the partially created hw device.  Attach our local
 110    callbacks.  Wire up our port names etc */
 111
 112 static hw_port_event_method tx3904cpu_port_event;
 113
 114
 115
 116 static void
 117 tx3904cpu_finish (struct hw *me)
 118 {
 119   struct tx3904cpu *controller;
 120
 121   controller = HW_ZALLOC (me, struct tx3904cpu);
 122   set_hw_data (me, controller);
 123   set_hw_ports (me, tx3904cpu_ports);
 124   set_hw_port_event (me, tx3904cpu_port_event);
 125
 126   /* Initialize the pending interrupt flags */
 127   controller->pending_level = 0;
 128   controller->pending_reset = 0;
 129   controller->pending_nmi = 0;
 130   controller->event = NULL;
 131 }
 132
 133
 134
 135 /* An event arrives on an interrupt port */
 136
 137 static void
 138 deliver_tx3904cpu_interrupt (struct hw *me,
 139                             void *data)
 140 {
 141   struct tx3904cpu *controller = hw_data (me);
 142   SIM_DESC sd = hw_system (me);
 143   sim_cpu *cpu = STATE_CPU (sd, 0); /* NB: fix CPU 0. */
 144   address_word cia = CPU_PC_GET (cpu);
 145
 146 #define CPU cpu
 147 #define SD sd
 148
 149   if (controller->pending_reset)
 150     {
 151       controller->pending_reset = 0;
 152       HW_TRACE ((me, "reset pc=0x%08lx", (long) CPU_PC_GET (cpu)));
 153       SignalExceptionNMIReset();
 154     }
 155   else if (controller->pending_nmi)
 156     {
 157       controller->pending_nmi = 0;
 158       HW_TRACE ((me, "nmi pc=0x%08lx", (long) CPU_PC_GET (cpu)));
 159       SignalExceptionNMIReset();
 160     }
 161   else if (controller->pending_level)
 162     {
 163       HW_TRACE ((me, "interrupt level=%d pc=0x%08lx sr=0x%08lx",
 164                  controller->pending_level,
 165                  (long) CPU_PC_GET (cpu), (long) SR));
 166
 167       /* Clear CAUSE register.  It may stay this way if the interrupt
 168          was cleared with a negative pending_level. */
 169       CAUSE &= ~ (cause_IP_mask << cause_IP_shift);
 170
 171       if(controller->pending_level > 0) /* interrupt set */
 172         {
 173           /* set hardware-interrupt subfields of CAUSE register */
 174           CAUSE |= (controller->pending_level & cause_IP_mask) << cause_IP_shift;
 175
 176           /* check for enabled / unmasked interrupts */
 177           if((SR & status_IEc) &&
 178              (controller->pending_level & ((SR >> status_IM_shift) & status_IM_mask)))
 179             {
 180               controller->pending_level = 0;
 181               SignalExceptionInterrupt(0 /* dummy value */);
 182             }
 183           else
 184             {
 185               /* reschedule soon */
 186               if(controller->event != NULL)
 187                 hw_event_queue_deschedule(me, controller->event);
 188               controller->event =
 189                 hw_event_queue_schedule (me, 1, deliver_tx3904cpu_interrupt, NULL);
 190             }
 191         } /* interrupt set */
 192     }
 193 #undef CPU
 194 #undef SD
 195 }
 196
 197
 198 static void
 199 tx3904cpu_port_event (struct hw *me,
 200                      int my_port,
 201                      struct hw *source,
 202                      int source_port,
 203                      int level)
 204 {
 205   struct tx3904cpu *controller = hw_data (me);
 206
 207   switch (my_port)
 208     {
 209     case RESET_PORT:
 210       controller->pending_reset = 1;
 211       HW_TRACE ((me, "port-in reset"));
 212       break;
 213
 214     case NMI_PORT:
 215       controller->pending_nmi = 1;
 216       HW_TRACE ((me, "port-in nmi"));
 217       break;
 218
 219     case LEVEL_PORT:
 220       /* level == 0 means that the interrupt was cleared */
 221       if(level == 0)
 222         controller->pending_level = -1; /* signal end of interrupt */
 223       else
 224         controller->pending_level = level;
 225       HW_TRACE ((me, "port-in level=%d", level));
 226       break;
 227
 228     default:
 229       hw_abort (me, "bad switch");
 230       break;
 231     }
 232
 233   /* Schedule an event to be delivered immediately after current
 234      instruction. */
 235   if(controller->event != NULL)
 236     hw_event_queue_deschedule(me, controller->event);
 237   controller->event =
 238     hw_event_queue_schedule (me, 0, deliver_tx3904cpu_interrupt, NULL);
 239 }
 240
 241
 242 const struct hw_descriptor dv_tx3904cpu_descriptor[] = {
 243   { "tx3904cpu", tx3904cpu_finish, },
 244   { NULL },
 245 };