contrib/loaders/flash/pic32mx.s

   1 /***************************************************************************
   2  *   Copyright (C) 2010 by Spencer Oliver                                  *
   3  *   spen@spen-soft.co.uk                                                  *
   4  *                                                                         *
   5  *   This program is free software; you can redistribute it and/or modify  *
   6  *   it under the terms of the GNU General Public License as published by  *
   7  *   the Free Software Foundation; either version 2 of the License, or     *
   8  *   (at your option) any later version.                                   *
   9  *                                                                         *
  10  *   This program is distributed in the hope that it will be useful,       *
  11  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  12  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  13  *   GNU General Public License for more details.                          *
  14  *                                                                         *
  15  *   You should have received a copy of the GNU General Public License     *
  16  *   along with this program; if not, write to the                         *
  17  *   Free Software Foundation, Inc.,                                       *
  18  *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
  19  ***************************************************************************/
  20
  21         .text
  22         .set noreorder
  23         .set noat
  24
  25 /* params:
  26  * $a0 src adr - ram + result
  27  * $a1 dest adr - flash
  28  * $a2 count (32bit words)
  29  * vars
  30  *
  31  * temps:
  32  * $t0, $t1, $t2, $t3, $t4, $t5
  33  * $s0, $s1, $s3, $s4, $s5
  34  */
  35
  36         .type main, @function
  37         .global main
  38
  39 .ent main
  40 main:
  41         /* setup constants */
  42         lui             $t0, 0xaa99
  43         ori             $t0, 0x6655                             /* NVMKEY1 */
  44         lui             $t1, 0x5566
  45         ori             $t1, 0x99AA                             /* NVMKEY2 */
  46         lui             $t2, 0xBF80
  47         ori             $t2, 0xF400                             /* NVMCON */
  48         ori             $t3, $zero, 0x4003              /* NVMCON row write cmd */
  49         ori             $t4, $zero, 0x8000              /* NVMCON start cmd */
  50
  51 write_row:
  52         /* can we perform a row write: 128 32bit words */
  53         sltiu   $s3, $a2, 128
  54         bne             $s3, $zero, write_word
  55         ori             $t5, $zero, 0x4000              /* NVMCON clear cmd */
  56
  57         /* perform row write 512 bytes */
  58         sw              $a1, 32($t2)    /* set NVMADDR with dest addr - real addr */
  59         sw              $a0, 64($t2)    /* set NVMSRCADDR with src addr - real addr */
  60
  61         bal             progflash
  62         addiu   $a0, $a0, 512
  63         addiu   $a1, $a1, 512
  64         beq             $zero, $zero, write_row
  65         addiu   $a2, $a2, -128
  66
  67 write_word:
  68         /* write 32bit words */
  69         lui             $s5, 0xa000
  70         ori             $s5, 0x0000
  71         or              $a0, $a0, $s5                   /* convert to virtual addr */
  72
  73         beq             $zero, $zero, next_word
  74         ori             $t3, $zero, 0x4001              /* NVMCON word write cmd */
  75
  76 prog_word:
  77         lw              $s4, 0($a0)             /* load data - from virtual addr */
  78         sw              $s4, 48($t2)    /* set NVMDATA with data */
  79         sw              $a1, 32($t2)    /* set NVMADDR with dest addr - real addr */
  80
  81         bal             progflash
  82         addiu   $a0, $a0, 4
  83         addiu   $a1, $a1, 4
  84         addiu   $a2, $a2, -1
  85 next_word:
  86         bne             $a2, $zero, prog_word
  87         nop
  88
  89 done:
  90         beq             $zero, $zero, exit
  91         addiu   $a0, $zero, 0
  92
  93 error:
  94         /* save result to $a0 */
  95         addiu   $a0, $s1, 0
  96
  97 exit:
  98         sdbbp
  99 .end main
 100
 101         .type progflash, @function
 102         .global progflash
 103
 104 .ent progflash
 105 progflash:
 106         sw              $t3, 0($t2)             /* set NVMWREN */
 107         sw              $t0, 16($t2)    /* write NVMKEY1 */
 108         sw              $t1, 16($t2)    /* write NVMKEY2 */
 109         sw              $t4, 8($t2)             /* start operation */
 110
 111 waitflash:
 112         lw              $s0, 0($t2)
 113         and             $s0, $s0, $t4
 114         bne             $s0, $zero, waitflash
 115         nop
 116
 117         /* following is to comply with errata #34
 118          * 500ns delay required */
 119         nop
 120         nop
 121         nop
 122         nop
 123         /* check for errors */
 124         lw              $s1, 0($t2)
 125         andi    $s1, $zero, 0x3000
 126         bne             $s1, $zero, error
 127         sw              $t5, 4($t2)             /* clear NVMWREN */
 128         jr              $ra
 129         nop
 130
 131 .end progflash