drivers/block/swim_asm.S

   1 /*
   2  * low-level functions for the SWIM floppy controller
   3  *
   4  * needs assembly language because is very timing dependent
   5  * this controller exists only on macintosh 680x0 based
   6  *
   7  * Copyright (C) 2004,2008 Laurent Vivier <Laurent@lvivier.info>
   8  *
   9  * based on Alastair Bridgewater SWIM analysis, 2001
  10  * based on netBSD IWM driver (c) 1997, 1998 Hauke Fath.
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version
  15  * 2 of the License, or (at your option) any later version.
  16  *
  17  * 2004-08-21 (lv) - Initial implementation
  18  * 2008-11-05 (lv) - add get_swim_mode
  19  */
  20
  21         .equ    write_data,     0x0000
  22         .equ    write_mark,     0x0200
  23         .equ    write_CRC,      0x0400
  24         .equ    write_parameter,0x0600
  25         .equ    write_phase,    0x0800
  26         .equ    write_setup,    0x0a00
  27         .equ    write_mode0,    0x0c00
  28         .equ    write_mode1,    0x0e00
  29         .equ    read_data,      0x1000
  30         .equ    read_mark,      0x1200
  31         .equ    read_error,     0x1400
  32         .equ    read_parameter, 0x1600
  33         .equ    read_phase,     0x1800
  34         .equ    read_setup,     0x1a00
  35         .equ    read_status,    0x1c00
  36         .equ    read_handshake, 0x1e00
  37
  38         .equ    o_side, 0
  39         .equ    o_track, 1
  40         .equ    o_sector, 2
  41         .equ    o_size, 3
  42         .equ    o_crc0, 4
  43         .equ    o_crc1, 5
  44
  45         .equ    seek_time, 30000
  46         .equ    max_retry, 40
  47         .equ    sector_size, 512
  48
  49         .global swim_read_sector_header
  50 swim_read_sector_header:
  51         link    %a6, #0
  52         moveml  %d1-%d5/%a0-%a4,%sp@-
  53         movel   %a6@(0x0c), %a4
  54         bsr     mfm_read_addrmark
  55         moveml  %sp@+, %d1-%d5/%a0-%a4
  56         unlk    %a6
  57         rts
  58
  59 sector_address_mark:
  60         .byte   0xa1, 0xa1, 0xa1, 0xfe
  61 sector_data_mark:
  62         .byte   0xa1, 0xa1, 0xa1, 0xfb
  63
  64 mfm_read_addrmark:
  65         movel   %a6@(0x08), %a3
  66         lea     %a3@(read_handshake), %a2
  67         lea     %a3@(read_mark), %a3
  68         moveq   #-1, %d0
  69         movew   #seek_time, %d2
  70
  71 wait_header_init:
  72         tstb    %a3@(read_error - read_mark)
  73         moveb   #0x18, %a3@(write_mode0 - read_mark)
  74         moveb   #0x01, %a3@(write_mode1 - read_mark)
  75         moveb   #0x01, %a3@(write_mode0 - read_mark)
  76         tstb    %a3@(read_error - read_mark)
  77         moveb   #0x08, %a3@(write_mode1 - read_mark)
  78
  79         lea     sector_address_mark, %a0
  80         moveq   #3, %d1
  81
  82 wait_addr_mark_byte:
  83
  84         tstb    %a2@
  85         dbmi    %d2, wait_addr_mark_byte
  86         bpl     header_exit
  87
  88         moveb   %a3@, %d3
  89         cmpb    %a0@+, %d3
  90         dbne    %d1, wait_addr_mark_byte
  91         bne     wait_header_init
  92
  93         moveq   #max_retry, %d2
  94
  95 amark0: tstb    %a2@
  96         dbmi    %d2, amark0
  97         bpl     signal_nonyb
  98
  99         moveb   %a3@, %a4@(o_track)
 100
 101         moveq   #max_retry, %d2
 102
 103 amark1: tstb    %a2@
 104         dbmi    %d2, amark1
 105         bpl     signal_nonyb
 106
 107         moveb   %a3@, %a4@(o_side)
 108
 109         moveq   #max_retry, %d2
 110
 111 amark2: tstb    %a2@
 112         dbmi    %d2, amark2
 113         bpl     signal_nonyb
 114
 115         moveb   %a3@, %a4@(o_sector)
 116
 117         moveq   #max_retry, %d2
 118
 119 amark3: tstb    %a2@
 120         dbmi    %d2, amark3
 121         bpl     signal_nonyb
 122
 123         moveb   %a3@, %a4@(o_size)
 124
 125         moveq   #max_retry, %d2
 126
 127 crc0:   tstb    %a2@
 128         dbmi    %d2, crc0
 129         bpl     signal_nonyb
 130
 131         moveb   %a3@, %a4@(o_crc0)
 132
 133         moveq   #max_retry, %d2
 134
 135 crc1:   tstb    %a2@
 136         dbmi    %d2, crc1
 137         bpl     signal_nonyb
 138
 139         moveb   %a3@, %a4@(o_crc1)
 140
 141         tstb    %a3@(read_error - read_mark)
 142
 143 header_exit:
 144         moveq   #0, %d0
 145         moveb   #0x18, %a3@(write_mode0 - read_mark)
 146         rts
 147 signal_nonyb:
 148         moveq   #-1, %d0
 149         moveb   #0x18, %a3@(write_mode0 - read_mark)
 150         rts
 151
 152         .global swim_read_sector_data
 153 swim_read_sector_data:
 154         link    %a6, #0
 155         moveml  %d1-%d5/%a0-%a5,%sp@-
 156         movel   %a6@(0x0c), %a4
 157         bsr     mfm_read_data
 158         moveml  %sp@+, %d1-%d5/%a0-%a5
 159         unlk    %a6
 160         rts
 161
 162 mfm_read_data:
 163         movel   %a6@(0x08), %a3
 164         lea     %a3@(read_handshake), %a2
 165         lea     %a3@(read_data), %a5
 166         lea     %a3@(read_mark), %a3
 167         movew   #seek_time, %d2
 168
 169 wait_data_init:
 170         tstb    %a3@(read_error - read_mark)
 171         moveb   #0x18, %a3@(write_mode0 - read_mark)
 172         moveb   #0x01, %a3@(write_mode1 - read_mark)
 173         moveb   #0x01, %a3@(write_mode0 - read_mark)
 174         tstb    %a3@(read_error - read_mark)
 175         moveb   #0x08, %a3@(write_mode1 - read_mark)
 176
 177         lea     sector_data_mark, %a0
 178         moveq   #3, %d1
 179
 180         /* wait data address mark */
 181
 182 wait_data_mark_byte:
 183
 184         tstb    %a2@
 185         dbmi    %d2, wait_data_mark_byte
 186         bpl     data_exit
 187
 188         moveb   %a3@, %d3
 189         cmpb    %a0@+, %d3
 190         dbne    %d1, wait_data_mark_byte
 191         bne     wait_data_init
 192
 193         /* read data */
 194
 195         tstb    %a3@(read_error - read_mark)
 196
 197         movel   #sector_size-1, %d4             /* sector size */
 198 read_new_data:
 199         movew   #max_retry, %d2
 200 read_data_loop:
 201         moveb   %a2@, %d5
 202         andb    #0xc0, %d5
 203         dbne    %d2, read_data_loop
 204         beq     data_exit
 205         moveb   %a5@, %a4@+
 206         andb    #0x40, %d5
 207         dbne    %d4, read_new_data
 208         beq     exit_loop
 209         moveb   %a5@, %a4@+
 210         dbra    %d4, read_new_data
 211 exit_loop:
 212
 213         /* read CRC */
 214
 215         movew   #max_retry, %d2
 216 data_crc0:
 217
 218         tstb    %a2@
 219         dbmi    %d2, data_crc0
 220         bpl     data_exit
 221
 222         moveb   %a3@, %d5
 223
 224         moveq   #max_retry, %d2
 225
 226 data_crc1:
 227
 228         tstb    %a2@
 229         dbmi    %d2, data_crc1
 230         bpl     data_exit
 231
 232         moveb   %a3@, %d5
 233
 234         tstb    %a3@(read_error - read_mark)
 235
 236         moveb   #0x18, %a3@(write_mode0 - read_mark)
 237
 238         /* return number of bytes read */
 239
 240         movel   #sector_size, %d0
 241         addw    #1, %d4
 242         subl    %d4, %d0
 243         rts
 244 data_exit:
 245         moveb   #0x18, %a3@(write_mode0 - read_mark)
 246         moveq   #-1, %d0
 247         rts