contrib/loaders/flash/stm32x.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         .syntax unified
  23         .thumb
  24         .thumb_func
  25         .global write
  26
  27 /*
  28         r0 - source address
  29         r1 - target address
  30         r2 - count (halfword-16bit)
  31         r3 - result
  32         r4 - temp
  33 */
  34
  35 #define STM32_FLASH_CR_OFFSET   0x10                    /* offset of CR register in FLASH struct */
  36 #define STM32_FLASH_SR_OFFSET   0x0c                    /* offset of CR register in FLASH struct */
  37
  38 write:
  39         ldr             r4, STM32_FLASH_BASE
  40 write_half_word:
  41         movs    r3, #0x01
  42         str             r3, [r4, #STM32_FLASH_CR_OFFSET]        /* PG (bit0) == 1 => flash programming enabled */
  43         ldrh    r3, [r0], #0x02                                         /* read one half-word from src, increment ptr */
  44         strh    r3, [r1], #0x02                                         /* write one half-word from src, increment ptr */
  45 busy:
  46         ldr     r3, [r4, #STM32_FLASH_SR_OFFSET]
  47         tst     r3, #0x01                                                       /* BSY (bit0) == 1 => operation in progress */
  48         beq     busy                                                            /* wait more... */
  49         tst             r3, #0x14                                                       /* PGERR (bit2) == 1 or WRPRTERR (bit4) == 1 => error */
  50         bne             exit                                                            /* fail... */
  51         subs    r2, r2, #0x01                                           /* decrement counter */
  52         bne             write_half_word                                         /* write next half-word if anything left */
  53 exit:
  54         bkpt    #0x00
  55
  56 STM32_FLASH_BASE: .word 0x40022000                              /* base address of FLASH struct */