loader/loader_asm.s

   1 #
   2 # Copyright (c) 2007 Josef 'Jeff' Sipek
   3 #
   4
   5 #include "loader.h"
   6
   7 .text
   8         .align  4
   9 .globl __do_io
  10         .type   __do_io, @function
  11 __do_io:
  12         #
  13         # r4 = 0x80000000
  14         #
  15         XGR     %r4, %r4
  16         LHI     %r4, 0x8
  17         SLL     %r4, 20
  18         #
  19         # r14 = r14 & 0x7fffffff don't ask, it's strangely retarded
  20         #
  21         L       %r1,ADDRMASK(%r4)
  22         NR      %r14, %r1  # mask out the bit
  23
  24         # set up the interrupt handler
  25         MVC     0x1f0(16),IOPSW(%r4)    # SET NEW IO PSW
  26         LA      %r1,IOHANDLER(%r4)      # GET HANDLER ADDRESS
  27         STG     %r1,0x1f0+8             # SAVE IN NEW PSW
  28
  29         L       %r1, 0xb8               # load subsystem ID
  30
  31         SSCH    ORB(%r4)                # issue IO
  32
  33         # Load Control Register 6 with I/O interrupt subclass mask
  34         STCTG   6,6,TMPVAR(%r4)         # GET CR6
  35         OI      TMPVAR+4(%r4),0xFF      # enable all
  36         LCTLG   6,6,TMPVAR(%r4)         # RELOAD MODIFIED CR6
  37
  38 /*
  39 7) Enable the PSW for I/O interrupts and go into wait state (you need bits 6, 12 & 14 set to 1 in the PSW : X'020A000000000000' is a good example)
  40 */
  41         LPSWE   WAITPSW(%r4)
  42
  43 #
  44 # The IO interrupt handler
  45 #
  46 .globl IOHANDLER
  47 IOHANDLER:
  48         # is this for us?
  49         L       %r1, MAGICVAL(%r4)
  50         C       %r1, 0xbc
  51         BNE     IONOTDONE(%r4)
  52
  53         # it is!
  54
  55         L       %r1, 0xb8               # load subsystem ID
  56
  57         TSCH    IRB(%r4)
  58
  59 /*
  60 FIXME: we should do more checking!
  61
  62 11) If Unit check or Channel Status|=0 : An I/O error occurred and act accordingly
  63 12) If unit exception : End of media (for tape & cards) and act accordingly
  64 13) If device end : I/O Completed.. Perform post I/O stuff (like advancing your pointers) and back to step 3
  65 */
  66
  67         # unit check? (end of media?)
  68         L       %r1,IRB+5(%r4)
  69         LA      %r0,0x02
  70         NR      %r0,%r1
  71         LA      %r2,1                   # return 1 - end of medium
  72         BCR     4,%r14                  # unit chk => return
  73
  74         # check the SCSW.. If CE Only : LPSW Old I/O PSW
  75         LA      %r0,0x04
  76         NR      %r0,%r1
  77         LA      %r2,0                   # means IO done
  78         BCR     4,%r14                  # device end => return
  79
  80 IONOTDONE:
  81         LPSWE   0x170
  82
  83 #
  84 # The PGM interrupt handler
  85 #
  86 .globl PGMHANDLER
  87 PGMHANDLER:
  88         STMG    %r1,%r3,0x200
  89
  90         # r3 = 0x80000000
  91         XGR     %r3, %r3
  92         LHI     %r3, 0x8
  93         SLL     %r3, 20
  94
  95         # is ILC == 3?
  96         LGH     %r2,0x8C
  97         CGHI    %r2,0x0006
  98         BNE     ERR
  99
 100         # grab the old PSW address, subtract length of TPROT, and compare it
 101         # with the TPROT opcode (0xe501)
 102         LG      %r1,0x158
 103         AGHI    %r1,-6
 104         LLGH    %r2,TPROTOP(%r3)
 105         LLGH    %r1,0(%r1)
 106         CGR     %r2,%r1
 107         BNE     ERR(%r3)
 108
 109         # set CC=3
 110         OI      0x152,0x30
 111
 112         LMG     %r1,%r3,0x200
 113
 114         LPSWE   0x150
 115
 116 ERR:
 117 .byte   0x00, 0x00
 118
 119
 120 #
 121 # Useful data
 122 #
 123 .data
 124 .globl TPROTOP
 125 TPROTOP:
 126 .byte   0xe5, 0x01
 127
 128         .align 8
 129 .globl IOPSW
 130 IOPSW:
 131         .byte   0x00
 132                 #   bits  value   name                        desc
 133                 #      0      0   <zero>
 134                 #      1      0   PER Mask (R)                disabled
 135                 #    2-4      0   <zero>
 136                 #      5      0   DAT Mode (T)                disabled
 137                 #      6      0   I/O Mask (IO)               enabled
 138                 #      7      0   External Mask (EX)          disabled
 139
 140         .byte   0x00
 141                 #   bits  value   name                        desc
 142                 #   8-11      0   Key
 143                 #     12      0   <one>
 144                 #     13      0   Machine-Check Mask (M)      disabled
 145                 #     14      0   Wait State (W)              executing
 146                 #     15      0   Problem State (P)           supervisor state
 147
 148         .byte   0x00
 149                 #   bits  value   name                        desc
 150                 #  16-17      0   Address-Space Control (AS)  disabled
 151                 #  18-19      0   Condition Code (CC)
 152                 #  20-23      0   Program Mask                exceptions disabled
 153
 154         .byte   0x01
 155                 #   bits  value   name                        desc
 156                 #  24-30      0   <zero>
 157                 #     31      1   Extended Addressing (EA)    EA + BA = 64 mode
 158
 159         .byte   0x80
 160         .byte   0x00
 161         .byte   0x00
 162         .byte   0x00
 163         .byte   0x00
 164         .byte   0x00
 165         .byte   0x00
 166         .byte   0x00
 167         .byte   0x00
 168         .byte   0x00
 169         .byte   0x00
 170         .byte   0x00
 171                 #   bits  value   name                        desc
 172                 #     32      1   Basic Addressing (BA)       BA = 31, !BA = 24
 173                 #  33-63      0   <zero>
 174                 # 64-127   addr   Instruction Address         Address to exec
 175
 176 .globl WAITPSW
 177 WAITPSW:
 178         .byte   0x02
 179                 #   bits  value   name                        desc
 180                 #      0      0   <zero>
 181                 #      1      0   PER Mask (R)                disabled
 182                 #    2-4      0   <zero>
 183                 #      5      0   DAT Mode (T)                disabled
 184                 #      6      1   I/O Mask (IO)               enabled
 185                 #      7      0   External Mask (EX)          disabled
 186
 187         .byte   0x02
 188                 #   bits  value   name                        desc
 189                 #   8-11      0   Key
 190                 #     12      0   <zero>
 191                 #     13      0   Machine-Check Mask (M)      disabled
 192                 #     14      1   Wait State (W)              not executing
 193                 #     15      0   Problem State (P)           supervisor state
 194
 195         .byte   0x00
 196                 #   bits  value   name                        desc
 197                 #  16-17      0   Address-Space Control (AS)  disabled
 198                 #  18-19      0   Condition Code (CC)
 199                 #  20-23      0   Program Mask                exceptions disabled
 200
 201         .byte   0x01
 202                 #   bits  value   name                        desc
 203                 #  24-30      0   <zero>
 204                 #     31      1   Extended Addressing (EA)    EA + BA = 64 mode
 205
 206         .byte   0x80
 207         .byte   0x00
 208         .byte   0x00
 209         .byte   0x00
 210         .byte   0x00
 211         .byte   0x00
 212         .byte   0x00
 213         .byte   0x00
 214         .byte   0x00
 215         .byte   0x00
 216         .byte   0x00
 217         .byte   0x00
 218                 #   bits  value   name                        desc
 219                 #     32      1   Basic Addressing (BA)       BA = 31, !BA = 24
 220                 #  33-63      0   <zero>
 221                 # 64-127   addr   Instruction Address         Address to exec
 222
 223 .globl TMPVAR
 224 TMPVAR:
 225         .8byte 0x0
 226
 227 .globl ADDRMASK
 228 ADDRMASK:
 229         .4byte 0x7fffffff
 230
 231 .globl MAGICVAL
 232 MAGICVAL:
 233         .4byte 0x12345678
 234
 235 .globl IRB
 236 IRB:
 237         .8byte 0x00
 238         .8byte 0x00
 239         .8byte 0x00
 240         .8byte 0x00
 241         .8byte 0x00
 242         .8byte 0x00
 243         .8byte 0x00
 244         .8byte 0x00
 245         .8byte 0x00
 246         .8byte 0x00
 247         .8byte 0x00
 248         .8byte 0x00
 249