firmware/spminterface.h

   1 /* Name: spminterface.h
   2  * Project: USBaspLoader
   3  * Author: Stephan Baerwolf
   4  * Creation Date: 2012-08-01
   5  * Copyright: (c) 2012 by Stephan Baerwolf
   6  * License: GNU GPL v2 (see License.txt)
   7  */
   8
   9 #ifndef SPMINTERFACE_H_f70ba6adf7624275947e859bdbff0599
  10 #define SPMINTERFACE_H_f70ba6adf7624275947e859bdbff0599
  11
  12 /*
  13  * spminterface.h offers a lightweight interface by inserting
  14  * an small machine-subroutine into the bootsection. (right
  15  * after the interrupt-vector-table)
  16  * This subroutine can be called by normal code in order to
  17  * enable it to program the flash (and depending on BLB11-lockbit
  18  * also the bootsection itself). Since SPM-calls from RWW-sections
  19  * will fail to work. The Routine will be called "bootloader__do_spm".
  20  * Its principle assembler-code is depicted below (real code is a
  21  * little machinedependen).
  22  * Interfaces will be the 8-bit registers r10..r13, for details
  23  * also see below. As also the pageaddress-registes (Z and rampZ)
  24  * are interfaced via different registers, it is possible to call
  25  * this routine via indirect call (icall).
  26  * Traditionally it is also possible to rcall, therefore you can
  27  * define "bootloader__do_spm" for your normal code via defsym at
  28  * linking time.
  29  * Example for an atmega8: "-Wl,--defsym=transfer_point=0x1826"
  30  * (since BOOTLOADER_ADDRESS is 0x1800 and there are
  31  * 2x19 = 38 = 0x26 byte for interrupts)
  32  *
  33
  34 bootloader__do_spm:
  35 ;disable interrupts (if enabled) before calling!
  36 ;you may also want to disable wdt, since this routine may busy-loop
  37 ;==================================================================
  38 ;-->INPUT:
  39 ;spmcr (spmcrval determines SPM action) will be register:       r10
  40 ;MCU dependend RA(MPZ should be transfered within register:     r11
  41 ;lo8(Z) should be transfered within register:                   r12
  42 ;hi8(Z) should be transfered within register:                   r13
  43
  44 ;<-->USED/CHANGED:
  45 ;temp0 will be register:                                        r11
  46 ;temp1 will be register:                                        r12
  47 ;temp2 will be register:                                        r13
  48 ;Z (r31:r30) wil be changed during operation
  49
  50 ;<--OUT:
  51 ;==================================================================
  52
  53 ;load pageaddress (Z) from r13:12 since it may was used for icall
  54 mov     rampZ,  r11
  55 mov     r30,    r12
  56 mov     r31,    r13
  57
  58 wait:                   ;check for previous SPM complete
  59 in      temp1, SPMCR
  60 sbrc    temp1, SPMEN
  61 rjmp    wait
  62
  63 out     SPMCR, spmcrval ;SPM timed sequence
  64 spm
  65
  66 ret
  67
  68 *
  69 */
  70
  71 #include <avr/io.h>
  72 #include <avr/pgmspace.h>
  73
  74 #ifndef BOOTLOADER_ADDRESS
  75 // this header is the interface for user-code
  76
  77
  78
  79
  80 #else /*ifndef BOOTLOADER_ADDRESS*/
  81 // this header is used directly within bootloader_do_spm
  82 #include "bootloaderconfig.h"
  83
  84 #if HAVE_SPMINTEREFACE
  85
  86
  87 /*
  88  * insert architecture dependend "bootloader_do_spm"-code
  89  *
  90  * try to make this array as big as possible
  91  * (so bootloader always uses 2kbytes flash)
  92  */
  93 #if defined (__AVR_ATmega8__) || defined (__AVR_ATmega8HVA__)
  94 //assume  SPMCR==0x37, SPMEN==0x00
  95 const uint16_t bootloader__do_spm[22] PROGMEM = {0x0000, 0x2dec, 0x2dfd, 0xb6c7, 0xfcc0, 0xcffd, 0xbea7, 0x95e8, 0x9508,
  96                                                  0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
  97                                                  0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF};
  98 #else
  99   #error "bootloader__do_spm has to be adapted, since there is no architecture code, yet"
 100 #endif
 101
 102
 103 #endif
 104 #endif /*ifdef BOOTLOADER_ADDRESS*/
 105
 106 #endif