/* $Id: head.S,v 1.6 2003/04/09 08:12:43 pkj Exp $
*
* Rescue code, made to reside at the beginning of the
* flash-memory. when it starts, it checks a partition
* table at the first sector after the rescue sector.
* the partition table was generated by the product builder
* script and contains offsets, lengths, types and checksums
* for each partition that this code should check.
*
* If any of the checksums fail, we assume the flash is so
* corrupt that we cant use it to boot into the ftp flash
* loader, and instead we initialize the serial port to
* receive a flash-loader and new flash image. we dont include
* any flash code here, but just accept a certain amount of
* bytes from the serial port and jump into it. the downloaded
* code is put in the cache.
*
* The partitiontable is designed so that it is transparent to
* code execution - it has a relative branch opcode in the
* beginning that jumps over it. each entry contains extra
* data so we can add stuff later.
*
* Partition table format:
*
* Code transparency:
*
* 2 bytes [opcode 'nop']
* 2 bytes [opcode 'di']
* 4 bytes [opcode 'ba <offset>', 8-bit or 16-bit version]
* 2 bytes [opcode 'nop', delay slot]
*
* Table validation (at +10):
*
* 2 bytes [magic/version word for partitiontable - 0xef, 0xbe]
* 2 bytes [length of all entries plus the end marker]
* 4 bytes [checksum for the partitiontable itself]
*
* Entries, each with the following format, last has offset -1:
*
* 4 bytes [offset in bytes, from start of flash]
* 4 bytes [length in bytes of partition]
* 4 bytes [checksum, simple longword sum]
* 2 bytes [partition type]
* 2 bytes [flags, only bit 0 used, ro/rw = 1/0]
* 16 bytes [reserved for future use]
*
* End marker
*
* 4 bytes [-1]
*
* 10 bytes [0, padding]
*
* Bit 0 in flags signifies RW or RO. The rescue code only bothers
* to check the checksum for RO partitions, since the others will
* change their data without updating the checksums. A 1 in bit 0
* means RO, 0 means RW. That way, it is possible to set a partition
* in RO mode initially, and later mark it as RW, since you can always
* write 0's to the flash.
*
* During the wait for serial input, the status LED will flash so the
* user knows something went wrong.
*
* Copyright (C) 1999, 2000, 2001, 2002, 2003 Axis Communications AB
*/
#include <linux/config.h>
#define ASSEMBLER_MACROS_ONLY
#include <asm/arch/sv_addr_ag.h>
;; The partitiontable is looked for at the first sector after the boot
;; sector. Sector size is 65536 bytes in all flashes we use.
#define PTABLE_START CONFIG_ETRAX_PTABLE_SECTOR
#define PTABLE_MAGIC 0xbeef
;; The normal Etrax100 on-chip boot ROM does serial boot at 0x380000f0.
;; That is not where we put our downloaded serial boot-code. The length is
;; enough for downloading code that loads the rest of itself (after
;; having setup the DRAM etc). It is the same length as the on-chip
;; ROM loads, so the same host loader can be used to load a rescued
;; product as well as one booted through the Etrax serial boot code.
#define CODE_START 0x40000000
#define CODE_LENGTH 784
#ifdef CONFIG_ETRAX_RESCUE_SER0
#define SERXOFF R_SERIAL0_XOFF
#define SERBAUD R_SERIAL0_BAUD
#define SERRECC R_SERIAL0_REC_CTRL
#define SERRDAT R_SERIAL0_REC_DATA
#define SERSTAT R_SERIAL0_STATUS
#endif
#ifdef CONFIG_ETRAX_RESCUE_SER1
#define SERXOFF R_SERIAL1_XOFF
#define SERBAUD R_SERIAL1_BAUD
#define SERRECC R_SERIAL1_REC_CTRL
#define SERRDAT R_SERIAL1_REC_DATA
#define SERSTAT R_SERIAL1_STATUS
#endif
#ifdef CONFIG_ETRAX_RESCUE_SER2
#define SERXOFF R_SERIAL2_XOFF
#define SERBAUD R_SERIAL2_BAUD
#define SERRECC R_SERIAL2_REC_CTRL
#define SERRDAT R_SERIAL2_REC_DATA
#define SERSTAT R_SERIAL2_STATUS
#endif
#ifdef CONFIG_ETRAX_RESCUE_SER3
#define SERXOFF R_SERIAL3_XOFF
#define SERBAUD R_SERIAL3_BAUD
#define SERRECC R_SERIAL3_REC_CTRL
#define SERRDAT R_SERIAL3_REC_DATA
#define SERSTAT R_SERIAL3_STATUS
#endif
#define NOP_DI 0xf025050f
#define RAM_INIT_MAGIC 0x56902387
.text
;; This is the entry point of the rescue code
;; 0x80000000 if loaded in flash (as it should be)
;; since etrax actually starts at address 2 when booting from flash, we
;; put a nop (2 bytes) here first so we dont accidentally skip the di
nop
di
jump in_cache ; enter cached area instead
in_cache:
;; first put a jump test to give a possibility of upgrading the rescue code
;; without erasing/reflashing the sector. we put a longword of -1 here and if
;; it is not -1, we jump using the value as jump target. since we can always
;; change 1's to 0's without erasing the sector, it is possible to add new
;; code after this and altering the jumptarget in an upgrade.
jtcd: move.d [jumptarget], $r0
cmp.d 0xffffffff, $r0
beq no_newjump
nop
jump [$r0]
jumptarget:
.dword 0xffffffff ; can be overwritten later to insert new code
no_newjump:
#ifdef CONFIG_ETRAX_ETHERNET
;; Start MII clock to make sure it is running when tranceiver is reset
move.d 0x3, $r0 ; enable = on, phy = mii_clk
move.d $r0, [R_NETWORK_GEN_CONFIG]
#endif
;; We need to setup the bus registers before we start using the DRAM
#include "../../lib/dram_init.S"
;; we now should go through the checksum-table and check the listed
;; partitions for errors.
move.d PTABLE_START, $r3
move.d [$r3], $r0
cmp.d NOP_DI, $r0 ; make sure the nop/di is there...
bne do_rescue
nop
;; skip the code transparency block (10 bytes).
addq 10, $r3
;; check for correct magic
move.w [$r3+], $r0
cmp.w PTABLE_MAGIC, $r0
bne do_rescue ; didn't recognize - trig rescue
nop
;; check for correct ptable checksum
movu.w [$r3+], $r2 ; ptable length
move.d $r2, $r8 ; save for later, length of total ptable
addq 28, $r8 ; account for the rest
move.d [$r3+], $r4 ; ptable checksum
move.d $r3, $r1
jsr checksum ; r1 source, r2 length, returns in r0
cmp.d $r0, $r4
bne do_rescue ; didn't match - trig rescue
nop
;; ptable is ok. validate each entry.
moveq -1, $r7
ploop: move.d [$r3+], $r1 ; partition offset (from ptable start)
bne notfirst ; check if it is the partition containing ptable
nop ; yes..
move.d $r8, $r1 ; for its checksum check, skip the ptable
move.d [$r3+], $r2 ; partition length
sub.d $r8, $r2 ; minus the ptable length
ba bosse
nop
notfirst:
cmp.d -1, $r1 ; the end of the ptable ?
beq flash_ok ; if so, the flash is validated
move.d [$r3+], $r2 ; partition length
bosse: move.d [$r3+], $r5 ; checksum
move.d [$r3+], $r4 ; type and flags
addq 16, $r3 ; skip the reserved bytes
btstq 16, $r4 ; check ro flag
bpl ploop ; rw partition, skip validation
nop
btstq 17, $r4 ; check bootable flag
bpl 1f
nop
move.d $r1, $r7 ; remember boot partition offset
1:
add.d PTABLE_START, $r1
jsr checksum ; checksum the partition
cmp.d $r0, $r5
beq ploop ; checksums matched, go to next entry
nop
;; otherwise fall through to the rescue code.
do_rescue:
;; setup port PA and PB default initial directions and data
;; (so we can flash LEDs, and so that DTR and others are set)
move.b CONFIG_ETRAX_DEF_R_PORT_PA_DIR, $r0
move.b $r0, [R_PORT_PA_DIR]
move.b CONFIG_ETRAX_DEF_R_PORT_PA_DATA, $r0
move.b $r0, [R_PORT_PA_DATA]
move.b CONFIG_ETRAX_DEF_R_PORT_PB_DIR, $r0
move.b $r0, [R_PORT_PB_DIR]
move.b CONFIG_ETRAX_DEF_R_PORT_PB_DATA, $r0
move.b $r0, [R_PORT_PB_DATA]
;; setup the serial port at 115200 baud
moveq 0, $r0
move.d $r0, [SERXOFF]
move.b 0x99, $r0
move.b $r0, [SERBAUD] ; 115.2kbaud for both transmit and receive
move.b 0x40, $r0 ; rec enable
move.b $r0, [SERRECC]
moveq 0, $r1 ; "timer" to clock out a LED red flash
move.d CODE_START, $r3 ; destination counter
movu.w CODE_LENGTH, $r4; length
wait_ser:
addq 1, $r1
#ifndef CONFIG_ETRAX_NO_LEDS
#ifdef CONFIG_ETRAX_PA_LEDS
move.b CONFIG_ETRAX_DEF_R_PORT_PA_DATA, $r2
#endif
#ifdef CONFIG_ETRAX_PB_LEDS
move.b CONFIG_ETRAX_DEF_R_PORT_PB_DATA, $r2
#endif
move.d (1 << CONFIG_ETRAX_LED1R) | (1 << CONFIG_ETRAX_LED2R), $r0
btstq 16, $r1
bpl 1f
nop
or.d $r0, $r2 ; set bit
ba 2f
nop
1: not $r0 ; clear bit
and.d $r0, $r2
2:
#ifdef CONFIG_ETRAX_PA_LEDS
move.b $r2, [R_PORT_PA_DATA]
#endif
#ifdef CONFIG_ETRAX_PB_LEDS
move.b $r2, [R_PORT_PB_DATA]
#endif
#ifdef CONFIG_ETRAX_90000000_LEDS
move.b $r2, [0x90000000]
#endif
#endif
;; check if we got something on the serial port
move.b [SERSTAT], $r0
btstq 0, $r0 ; data_avail
bpl wait_ser
nop
;; got something - copy the byte and loop
move.b [SERRDAT], $r0
move.b $r0, [$r3+]
subq 1, $r4 ; decrease length
bne wait_ser
nop
;; jump into downloaded code
move.d RAM_INIT_MAGIC, $r8 ; Tell next product that DRAM is initialized
jump CODE_START
flash_ok:
;; check r7, which contains either -1 or the partition to boot from
cmp.d -1, $r7
bne 1f
nop
move.d PTABLE_START, $r7; otherwise use the ptable start
1:
move.d RAM_INIT_MAGIC, $r8 ; Tell next product that DRAM is initialized
jump $r7 ; boot!
;; Helper subroutines
;; Will checksum by simple addition
;; r1 - source
;; r2 - length in bytes
;; result will be in r0
checksum:
moveq 0, $r0
1: addu.b [$r1+], $r0
subq 1, $r2
bne 1b
nop
ret
nop
