contrib/loaders/flash/stm32/stm32h7x.S

   1 /***************************************************************************
   2  *   Copyright (C) 2017 by STMicroelectronics                              *
   3  *                                                                         *
   4  *   This program is free software; you can redistribute it and/or modify  *
   5  *   it under the terms of the GNU General Public License as published by  *
   6  *   the Free Software Foundation; either version 2 of the License, or     *
   7  *   (at your option) any later version.                                   *
   8  *                                                                         *
   9  *   This program is distributed in the hope that it will be useful,       *
  10  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  11  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  12  *   GNU General Public License for more details.                          *
  13  *                                                                         *
  14  *   You should have received a copy of the GNU General Public License     *
  15  *   along with this program; if not, write to the                         *
  16  *   Free Software Foundation, Inc.                                        *
  17  ***************************************************************************/
  18
  19         .text
  20         .syntax unified
  21         .cpu cortex-m4
  22         .thumb
  23
  24 /*
  25  * Code limitations:
  26  * The workarea must have size multiple of 4 bytes, since R/W
  27  * operations are all at 32 bits.
  28  * The workarea must be big enough to contain rp, wp and data, thus the minumum
  29  * workarea size is: min_wa_size = sizeof(rp, wp, data) = 4 + 4 + sizeof(data).
  30  *  - for 0x450 devices: sizeof(data) = 32 bytes, thus min_wa_size = 40 bytes.
  31  *  - for 0x480 devices: sizeof(data) = 16 bytes, thus min_wa_size = 24 bytes.
  32  * To benefit from concurrent host write-to-buffer and target
  33  * write-to-flash, the workarea must be way bigger than the minimum.
  34  *
  35  * To avoid confusions the write word size is got from .block_size member of
  36  * struct stm32h7x_part_info defined in stm32h7x.c
  37 */
  38
  39 /*
  40  * Params :
  41  * r0 = workarea start, status (out)
  42  * r1 = workarea end
  43  * r2 = target address
  44  * r3 = count (of write words)
  45  * r4 = size of write word
  46  * r5 = flash reg base
  47  *
  48  * Clobbered:
  49  * r6 - rp
  50  * r7 - wp, status, tmp
  51  * r8 - loop index, tmp
  52  */
  53
  54 #define STM32_FLASH_CR_OFFSET   0x0C    /* offset of CR register in FLASH struct */
  55 #define STM32_FLASH_SR_OFFSET   0x10    /* offset of SR register in FLASH struct */
  56 #define STM32_CR_PROG                   0x00000002      /* PG */
  57 #define STM32_SR_QW_MASK                0x00000004      /* QW */
  58 #define STM32_SR_ERROR_MASK             0x07ee0000      /* DBECCERR | SNECCERR | RDSERR | RDPERR | OPERR
  59                                                                                            | INCERR | STRBERR | PGSERR | WRPERR */
  60
  61         .thumb_func
  62         .global _start
  63 _start:
  64         ldr             r6, [r0, #4]            /* read rp */
  65
  66 wait_fifo:
  67         ldr             r7, [r0, #0]            /* read wp */
  68         cbz             r7, exit                        /* abort if wp == 0, status = 0 */
  69         subs    r7, r7, r6                      /* number of bytes available for read in r7 */
  70         ittt    mi                                      /* if wrapped around */
  71         addmi   r7, r1                          /* add size of buffer */
  72         submi   r7, r0
  73         submi   r7, #8
  74         cmp             r7, r4                          /* wait until data buffer is full */
  75         bcc             wait_fifo
  76
  77         mov             r7, #STM32_CR_PROG
  78         str             r7, [r5, #STM32_FLASH_CR_OFFSET]
  79
  80         mov             r8, #4
  81         udiv    r8, r4, r8                      /* number of words is size of write word devided by 4*/
  82 write_flash:
  83         dsb
  84         ldr             r7, [r6], #0x04         /* read one word from src, increment ptr */
  85         str             r7, [r2], #0x04         /* write one word to dst, increment ptr */
  86         dsb
  87         cmp             r6, r1                          /* if rp >= end of buffer ... */
  88         it              cs
  89         addcs   r6, r0, #8                      /* ... then wrap at buffer start */
  90         subs    r8, r8, #1                      /* decrement loop index */
  91         bne             write_flash                     /* loop if not done */
  92
  93 busy:
  94         ldr             r7, [r5, #STM32_FLASH_SR_OFFSET]
  95         tst             r7, #STM32_SR_QW_MASK
  96         bne             busy                            /* operation in progress, wait ... */
  97
  98         ldr             r8, =STM32_SR_ERROR_MASK
  99         tst             r7, r8
 100         bne             error                           /* fail... */
 101
 102         str             r6, [r0, #4]            /* store rp */
 103         subs    r3, r3, #1                      /* decrement count */
 104         bne             wait_fifo                       /* loop if not done */
 105         b               exit
 106
 107 error:
 108         movs    r8, #0
 109         str             r8, [r0, #4]            /* set rp = 0 on error */
 110
 111 exit:
 112         mov             r0, r7                          /* return status in r0 */
 113         bkpt    #0x00
 114
 115         .pool
 116