/*
   * 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 can't 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) 1999-2007 Axis Communications AB
   */
  
  #ifdef CONFIG_ETRAX_AXISFLASHMAP
  
  #define ASSEMBLER_MACROS_ONLY
  #include <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 "../../../arch-v10/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
  #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
  	moveq   CONFIG_ETRAX_FLASH1_SIZE, $r6
  
  	;; If the first physical flash memory is exceeded wrap to the
  	;; second one
  	btstq	26, $r1		; Are we addressing first flash?
  	bpl	1f
  	nop
  	clear.d	$r6
  
  1:	test.d  $r6		; 0 = no wrapping
  	beq	2f
  	nop
  	lslq	20, $r6		; Convert MB to bytes
  	sub.d	$r1, $r6
  
  2:	addu.b	[$r1+], $r0
  	subq	1, $r6		; Flash memory left
  	beq	3f
  	subq	1, $r2		; Length left
  	bne	2b
  	nop
  	ret
  	nop
  
  3:	move.d	MEM_CSE1_START, $r1 ; wrap to second flash
  	ba	2b
  	nop
  
  #endif