sim/mips/dv-tx3904cpu.c

   1 /*  This file is part of the program GDB, the GNU debugger.
   2
   3     Copyright (C) 1998-2024 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 /* This must come before any other includes.  */
  22 #include "defs.h"
  23
  24 #include "sim-main.h"
  25 #include "hw-main.h"
  26
  27 /* DEVICE
  28
  29
  30    tx3904cpu - tx3904 cpu virtual device
  31
  32
  33    DESCRIPTION
  34
  35
  36    Implements the external tx3904 functionality.  This includes the
  37    delivery of of interrupts generated from other devices and the
  38    handling of device specific registers.
  39
  40
  41    PROPERTIES
  42
  43    none
  44
  45
  46    PORTS
  47
  48
  49    reset (input)
  50
  51    Currently ignored.
  52
  53
  54    nmi (input)
  55
  56    Deliver a non-maskable interrupt to the processor.
  57
  58
  59    level (input)
  60
  61    Deliver a maskable interrupt of given level, corresponding to
  62    IP[5:0], to processor.
  63
  64
  65
  66    BUGS
  67
  68
  69    When delivering an interrupt, this code assumes that there is only
  70    one processor (number 0).
  71
  72    This code does not attempt to be efficient at handling pending
  73    interrupts.  It simply schedules the interrupt delivery handler
  74    every instruction cycle until all pending interrupts go away.  An
  75    alternative implementation might modify instructions that change
  76    the PSW and have them check to see if the change makes an interrupt
  77    delivery possible.
  78
  79    */
  80
  81
  82
  83 struct tx3904cpu {
  84   /* Pending interrupts for delivery by event handler */
  85   int pending_reset, pending_nmi, pending_level;
  86   struct hw_event* event;
  87 };
  88
  89
  90
  91 /* input port ID's */
  92
  93 enum {
  94   RESET_PORT,
  95   NMI_PORT,
  96   LEVEL_PORT,
  97 };
  98
  99
 100 static const struct hw_port_descriptor tx3904cpu_ports[] = {
 101
 102   /* interrupt inputs */
 103   { "reset", RESET_PORT, 0, input_port, },
 104   { "nmi", NMI_PORT, 0, input_port, },
 105   { "level", LEVEL_PORT, 0, input_port, },
 106
 107   { NULL, },
 108 };
 109
 110
 111 /* Finish off the partially created hw device.  Attach our local
 112    callbacks.  Wire up our port names etc */
 113
 114 static hw_port_event_method tx3904cpu_port_event;
 115
 116
 117
 118 static void
 119 tx3904cpu_finish (struct hw *me)
 120 {
 121   struct tx3904cpu *controller;
 122
 123   controller = HW_ZALLOC (me, struct tx3904cpu);
 124   set_hw_data (me, controller);
 125   set_hw_ports (me, tx3904cpu_ports);
 126   set_hw_port_event (me, tx3904cpu_port_event);
 127
 128   /* Initialize the pending interrupt flags */
 129   controller->pending_level = 0;
 130   controller->pending_reset = 0;
 131   controller->pending_nmi = 0;
 132   controller->event = NULL;
 133 }
 134
 135
 136
 137 /* An event arrives on an interrupt port */
 138
 139 static void
 140 deliver_tx3904cpu_interrupt (struct hw *me,
 141                             void *data)
 142 {
 143   struct tx3904cpu *controller = hw_data (me);
 144   SIM_DESC sd = hw_system (me);
 145   sim_cpu *cpu = STATE_CPU (sd, 0); /* NB: fix CPU 0. */
 146   address_word cia = CPU_PC_GET (cpu);
 147
 148 #define CPU cpu
 149 #define SD sd
 150
 151   if (controller->pending_reset)
 152     {
 153       controller->pending_reset = 0;
 154       HW_TRACE ((me, "reset pc=0x%08lx", (long) CPU_PC_GET (cpu)));
 155       SignalExceptionNMIReset();
 156     }
 157   else if (controller->pending_nmi)
 158     {
 159       controller->pending_nmi = 0;
 160       HW_TRACE ((me, "nmi pc=0x%08lx", (long) CPU_PC_GET (cpu)));
 161       SignalExceptionNMIReset();
 162     }
 163   else if (controller->pending_level)
 164     {
 165       HW_TRACE ((me, "interrupt level=%d pc=0x%08lx sr=0x%08lx",
 166                  controller->pending_level,
 167                  (long) CPU_PC_GET (cpu), (long) SR));
 168
 169       /* Clear CAUSE register.  It may stay this way if the interrupt
 170          was cleared with a negative pending_level. */
 171       CAUSE &= ~ (cause_IP_mask << cause_IP_shift);
 172
 173       if (controller->pending_level > 0) /* interrupt set */
 174         {
 175           /* set hardware-interrupt subfields of CAUSE register */
 176           CAUSE |= (controller->pending_level & cause_IP_mask) << cause_IP_shift;
 177
 178           /* check for enabled / unmasked interrupts */
 179           if ((SR & status_IEc) &&
 180              (controller->pending_level & ((SR >> status_IM_shift) & status_IM_mask)))
 181             {
 182               controller->pending_level = 0;
 183               SignalExceptionInterrupt(0 /* dummy value */);
 184             }
 185           else
 186             {
 187               /* reschedule soon */
 188               if (controller->event != NULL)
 189                 hw_event_queue_deschedule(me, controller->event);
 190               controller->event =
 191                 hw_event_queue_schedule (me, 1, deliver_tx3904cpu_interrupt, NULL);
 192             }
 193         } /* interrupt set */
 194     }
 195 #undef CPU
 196 #undef SD
 197 }
 198
 199
 200 static void
 201 tx3904cpu_port_event (struct hw *me,
 202                      int my_port,
 203                      struct hw *source,
 204                      int source_port,
 205                      int level)
 206 {
 207   struct tx3904cpu *controller = hw_data (me);
 208
 209   switch (my_port)
 210     {
 211     case RESET_PORT:
 212       controller->pending_reset = 1;
 213       HW_TRACE ((me, "port-in reset"));
 214       break;
 215
 216     case NMI_PORT:
 217       controller->pending_nmi = 1;
 218       HW_TRACE ((me, "port-in nmi"));
 219       break;
 220
 221     case LEVEL_PORT:
 222       /* level == 0 means that the interrupt was cleared */
 223       if (level == 0)
 224         controller->pending_level = -1; /* signal end of interrupt */
 225       else
 226         controller->pending_level = level;
 227       HW_TRACE ((me, "port-in level=%d", level));
 228       break;
 229
 230     default:
 231       hw_abort (me, "bad switch");
 232       break;
 233     }
 234
 235   /* Schedule an event to be delivered immediately after current
 236      instruction. */
 237   if (controller->event != NULL)
 238     hw_event_queue_deschedule(me, controller->event);
 239   controller->event =
 240     hw_event_queue_schedule (me, 0, deliver_tx3904cpu_interrupt, NULL);
 241 }
 242
 243
 244 const struct hw_descriptor dv_tx3904cpu_descriptor[] = {
 245   { "tx3904cpu", tx3904cpu_finish, },
 246   { NULL },
 247 };