1/* $Id: head.S,v 1.1.1.1 2008/10/15 03:26:00 james26_jang Exp $
2 *
3 * Rescue code, made to reside at the beginning of the
4 * flash-memory. when it starts, it checks a partition
5 * table at the first sector after the rescue sector.
6 * the partition table was generated by the product builder
7 * script and contains offsets, lengths, types and checksums
8 * for each partition that this code should check.
9 *
10 * If any of the checksums fail, we assume the flash is so
11 * corrupt that we cant use it to boot into the ftp flash
12 * loader, and instead we initialize the serial port to
13 * receive a flash-loader and new flash image. we dont include
14 * any flash code here, but just accept a certain amount of
15 * bytes from the serial port and jump into it. the downloaded
16 * code is put in the cache.
17 *
18 * The partitiontable is designed so that it is transparent to
19 * code execution - it has a relative branch opcode in the
20 * beginning that jumps over it. each entry contains extra
21 * data so we can add stuff later.
22 *
23 * Partition table format:
24 *
25 *     Code transparency:
26 *
27 *     2 bytes    [opcode 'nop']
28 *     2 bytes    [opcode 'di']
29 *     4 bytes    [opcode 'ba <offset>', 8-bit or 16-bit version]
30 *     2 bytes    [opcode 'nop', delay slot]
31 *
32 *     Table validation (at +10):
33 *
34 *     2 bytes    [magic/version word for partitiontable - 0xef, 0xbe]
35 *     2 bytes    [length of all entries plus the end marker]
36 *     4 bytes    [checksum for the partitiontable itself]
37 *
38 *     Entries, each with the following format, last has offset -1:
39 *
40 *        4 bytes    [offset in bytes, from start of flash]
41 *        4 bytes    [length in bytes of partition]
42 *        4 bytes    [checksum, simple longword sum]
43 *        2 bytes    [partition type]
44 *        2 bytes    [flags, only bit 0 used, ro/rw = 1/0]
45 *        16 bytes   [reserved for future use]
46 *
47 *     End marker
48 *
49 *        4 bytes    [-1]
50 *
51 *	 10 bytes    [0, padding]
52 *
53 * Bit 0 in flags signifies RW or RO. The rescue code only bothers
54 * to check the checksum for RO partitions, since the others will
55 * change its data without updating the checksums. A 1 in bit 0
56 * means RO, 0 means RW. That way, it is possible to set a partition
57 * in RO mode initially, and later mark it as RW, since you can always
58 * write 0's to the flash.
59 *
60 * During the wait for serial input, the status LED will flash so the
61 * user knows something went wrong.
62 *
63 * Copyright (C) 1999,2001 Axis Communications AB
64 */
65
66#include <linux/config.h>
67#define ASSEMBLER_MACROS_ONLY
68#include <asm/sv_addr_ag.h>
69
70	;; The partitiontable is looked for at the first sector after the boot
71	;; sector. Sector size is 65536 bytes in all flashes we use.
72
73#define PTABLE_START CONFIG_ETRAX_PTABLE_SECTOR
74#define PTABLE_MAGIC 0xbeef
75
76	;; The normal Etrax100 on-chip boot ROM does serial boot at 0x380000f0.
77	;; That is not where we put our downloaded serial boot-code. The length is
78	;; enough for downloading code that loads the rest of itself (after
79	;; having setup the DRAM etc). It is the same length as the on-chip
80	;; ROM loads, so the same host loader can be used to load a rescued
81	;; product as well as one booted through the Etrax serial boot code.
82
83#define CODE_START 0x40000000
84#define CODE_LENGTH 784
85
86#ifdef CONFIG_ETRAX_RESCUE_SER0
87#define SERXOFF R_SERIAL0_XOFF
88#define SERBAUD R_SERIAL0_BAUD
89#define SERRECC R_SERIAL0_REC_CTRL
90#define SERRDAT R_SERIAL0_REC_DATA
91#define SERSTAT R_SERIAL0_STATUS
92#endif
93#ifdef CONFIG_ETRAX_RESCUE_SER1
94#define SERXOFF R_SERIAL1_XOFF
95#define SERBAUD R_SERIAL1_BAUD
96#define SERRECC R_SERIAL1_REC_CTRL
97#define SERRDAT R_SERIAL1_REC_DATA
98#define SERSTAT R_SERIAL1_STATUS
99#endif
100#ifdef CONFIG_ETRAX_RESCUE_SER2
101#define SERXOFF R_SERIAL2_XOFF
102#define SERBAUD R_SERIAL2_BAUD
103#define SERRECC R_SERIAL2_REC_CTRL
104#define SERRDAT R_SERIAL2_REC_DATA
105#define SERSTAT R_SERIAL2_STATUS
106#endif
107#ifdef CONFIG_ETRAX_RESCUE_SER3
108#define SERXOFF R_SERIAL3_XOFF
109#define SERBAUD R_SERIAL3_BAUD
110#define SERRECC R_SERIAL3_REC_CTRL
111#define SERRDAT R_SERIAL3_REC_DATA
112#define SERSTAT R_SERIAL3_STATUS
113#endif
114
115#define NOP_DI 0xf025050f
116#define RAM_INIT_MAGIC 0x56902387
117
118	.text
119
120	;; This is the entry point of the rescue code
121	;; 0x80000000 if loaded in flash (as it should be)
122	;; since etrax actually starts at address 2 when booting from flash, we
123	;; put a nop (2 bytes) here first so we dont accidentally skip the di
124
125	nop
126	di
127
128	jump	in_cache	; enter cached area instead
129in_cache:
130
131	;; first put a jump test to give a possibility of upgrading the rescue code
132	;; without erasing/reflashing the sector. we put a longword of -1 here and if
133	;; its not -1, we jump using the value as jump target. since we can always
134	;; change 1's to 0's without erasing the sector, it is possible to add new
135	;; code after this and altering the jumptarget in an upgrade.
136
137jtcd:	move.d	[jumptarget], $r0
138	cmp.d	0xffffffff, $r0
139	beq	no_newjump
140	nop
141
142	jump	[$r0]
143
144jumptarget:
145	.dword	0xffffffff	; can be overwritten later to insert new code
146
147no_newjump:
148#ifdef CONFIG_ETRAX_ETHERNET
149	;; Start MII clock to make sure it is running when tranceiver is reset
150	move.d 0x3, $r0    ; enable = on, phy = mii_clk
151	move.d $r0, [R_NETWORK_GEN_CONFIG]
152#endif
153
154	;; We need to setup the bus registers before we start using the DRAM
155#include "../../lib/dram_init.S"
156
157	;; we now should go through the checksum-table and check the listed
158	;; partitions for errors.
159
160	move.d	PTABLE_START, $r3
161	move.d	[$r3], $r0
162	cmp.d	NOP_DI, $r0	; make sure the nop/di is there...
163	bne	do_rescue
164	nop
165
166	;; skip the code transparency block (10 bytes).
167
168	addq	10, $r3
169
170	;; check for correct magic
171
172	move.w	[$r3+], $r0
173	cmp.w	PTABLE_MAGIC, $r0
174	bne	do_rescue	; didn't recognize - trig rescue
175	nop
176
177	;; check for correct ptable checksum
178
179	movu.w	[$r3+], $r2	; ptable length
180	move.d	$r2, $r8	; save for later, length of total ptable
181	addq	28, $r8		; account for the rest
182	move.d	[$r3+], $r4	; ptable checksum
183	move.d	$r3, $r1
184	jsr	checksum	; r1 source, r2 length, returns in r0
185
186	cmp.d	$r0, $r4
187	bne	do_rescue	; didn't match - trig rescue
188	nop
189
190	;; ptable is ok. validate each entry.
191
192	moveq	-1, $r7
193
194ploop:	move.d	[$r3+], $r1	; partition offset (from ptable start)
195	bne	notfirst	; check if its the partition containing ptable
196	nop			; yes..
197	move.d	$r8, $r1	; for its checksum check, skip the ptable
198	move.d	[$r3+], $r2	; partition length
199	sub.d	$r8, $r2	; minus the ptable length
200	ba	bosse
201	nop
202notfirst:
203	cmp.d	-1, $r1		; the end of the ptable ?
204	beq	flash_ok	;   if so, the flash is validated
205	move.d	[$r3+], $r2	; partition length
206bosse:	move.d	[$r3+], $r5	; checksum
207	move.d	[$r3+], $r4	; type and flags
208	addq	16, $r3		; skip the reserved bytes
209	btstq	16, $r4		; check ro flag
210	bpl	ploop		;   rw partition, skip validation
211	nop
212	btstq	17, $r4		; check bootable flag
213	bpl	1f
214	nop
215	move.d	$r1, $r7	; remember boot partition offset
2161:
217
218	add.d	PTABLE_START, $r1
219
220	jsr	checksum	; checksum the partition
221
222	cmp.d	$r0, $r5
223	beq	ploop		; checksums matched, go to next entry
224	nop
225
226	;; otherwise fall through to the rescue code.
227
228do_rescue:
229	;; setup port PA and PB default initial directions and data
230	;; (so we can flash LEDs, and so that DTR and others are set)
231
232	move.b	CONFIG_ETRAX_DEF_R_PORT_PA_DIR, $r0
233	move.b	$r0, [R_PORT_PA_DIR]
234	move.b	CONFIG_ETRAX_DEF_R_PORT_PA_DATA, $r0
235	move.b	$r0, [R_PORT_PA_DATA]
236
237	move.b	CONFIG_ETRAX_DEF_R_PORT_PB_DIR, $r0
238	move.b	$r0, [R_PORT_PB_DIR]
239	move.b	CONFIG_ETRAX_DEF_R_PORT_PB_DATA, $r0
240	move.b	$r0, [R_PORT_PB_DATA]
241
242	;; setup the serial port at 115200 baud
243
244	moveq	0, $r0
245	move.d	$r0, [SERXOFF]
246
247	move.b	0x99, $r0
248	move.b	$r0, [SERBAUD]		; 115.2kbaud for both transmit and receive
249
250	move.b	0x40, $r0		; rec enable
251	move.b	$r0, [SERRECC]
252
253	moveq	0, $r1		; "timer" to clock out a LED red flash
254	move.d	CODE_START, $r3	; destination counter
255	movu.w	CODE_LENGTH, $r4; length
256
257wait_ser:
258	addq	1, $r1
259#ifndef CONFIG_ETRAX_NO_LEDS
260#ifdef CONFIG_ETRAX_PA_LEDS
261	move.b	CONFIG_ETRAX_DEF_R_PORT_PA_DATA, $r2
262#endif
263#ifdef CONFIG_ETRAX_PB_LEDS
264	move.b	CONFIG_ETRAX_DEF_R_PORT_PB_DATA, $r2
265#endif
266	move.d	(1 << CONFIG_ETRAX_LED1R) | (1 << CONFIG_ETRAX_LED2R), $r0
267	btstq	16, $r1
268	bpl	1f
269	nop
270	or.d	$r0, $r2	; set bit
271	ba	2f
272	nop
2731:	not	$r0		; clear bit
274	and.d	$r0, $r2
2752:
276#ifdef CONFIG_ETRAX_PA_LEDS
277	move.b	$r2, [R_PORT_PA_DATA]
278#endif
279#ifdef CONFIG_ETRAX_PB_LEDS
280	move.b	$r2, [R_PORT_PB_DATA]
281#endif
282#ifdef CONFIG_ETRAX_90000000_LEDS
283	move.b	$r2, [0x90000000]
284#endif
285#endif
286
287	;; check if we got something on the serial port
288
289	move.b	[SERSTAT], $r0
290	btstq	0, $r0		; data_avail
291	bpl	wait_ser
292	nop
293
294	;; got something - copy the byte and loop
295
296	move.b	[SERRDAT], $r0
297	move.b	$r0, [$r3+]
298
299	subq	1, $r4		; decrease length
300	bne	wait_ser
301	nop
302
303	;; jump into downloaded code
304
305	move.d	RAM_INIT_MAGIC, $r8	; Tell next product that DRAM is initialized
306	jump	CODE_START
307
308flash_ok:
309	;; check r7, which contains either -1 or the partition to boot from
310
311	cmp.d	-1, $r7
312	bne	1f
313	nop
314	move.d	PTABLE_START, $r7; otherwise use the ptable start
3151:
316	move.d	RAM_INIT_MAGIC, $r8	; Tell next product that DRAM is initialized
317	jump	$r7		; boot!
318
319
320	;; Helper subroutines
321
322	;; Will checksum by simple addition
323	;; r1 - source
324	;; r2 - length in bytes
325	;; result will be in r0
326checksum:
327	moveq	0, $r0
3281:	addu.b	[$r1+], $r0
329	subq	1, $r2
330	bne	1b
331	nop
332	ret
333	nop
334