/* $Id: head.S,v 1.10 2001/11/08 15:10:16 starvik 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 its 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) 1999,2001 Axis Communications AB */#include <linux/config.h>#define ASSEMBLER_MACROS_ONLY#include <asm/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 insteadin_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	;; its 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 its 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	nopnotfirst:		cmp.d	-1, $r1		; the end of the ptable ?	beq	flash_ok	;   if so, the flash is validated	move.d	[$r3+], $r2	; partition lengthbosse:	move.d	[$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 offset1:		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	nop1:	not	$r0		; clear bit	and.d	$r0, $r22:	#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_STARTflash_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 start1:	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 r0checksum:	moveq	0, $r01:	addu.b	[$r1+], $r0	subq	1, $r2	bne	1b	nop	ret	nop