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Software for White Rabbit PTP Core
Commit f3f55df3 authored by Wesley W. Terpstra's avatar Wesley W. Terpstra
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First version of the debug code needed to run gdb on ptp.

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/* LM32 JTAG relocatable debug ROM
*
* Load this code anywhere in memory and point DEBA at it.
* When DC=1 it chain loads the exception handlers at EBA.
* User exception handlers must save to the stack.
*
* Copyright (C) 2011 by Wesley W. Terpstra <w.terpstra@gsi.de>
*/
.section .boot, "ax", @progbits
.global _debug_unit
_debug_unit:
_reset_handler:
ori r0, ra, 0 /* Save RA before destroying it */
calli _find0
_find0: addi ra, ra, _registers-_find0 /* RA now points to _registers */
sw (ra+_gp-_registers), gp /* Save user GP */
ori gp, ra, 0 /* GP now points to _registers */
calli save_all
_eid_offset:
calli handle_debug_trap
bi _e_restore_and_return
_breakpoint_handler:
ori r0, ra, 0 /* Save RA before destroying it */
calli _find1
_find1: addi ra, ra, _registers-_find1 /* RA now points to _registers */
sw (ra+_gp-_registers), gp /* Save user GP */
ori gp, ra, 0 /* GP now points to _registers */
calli save_all
calli handle_debug_trap
bi _b_restore_and_return
_instruction_bus_error_handler:
ori r0, ra, 0 /* Save RA before destroying it */
calli _find2
_find2: addi ra, ra, _registers-_find2 /* RA now points to _registers */
sw (ra+_gp-_registers), gp /* Save user GP */
ori gp, ra, 0 /* GP now points to _registers */
calli save_all
calli handle_debug_trap
bi _e_restore_and_return
_watchpoint_handler:
ori r0, ra, 0 /* Save RA before destroying it */
calli _find3
_find3: addi ra, ra, _registers-_find3 /* RA now points to _registers */
sw (ra+_gp-_registers), gp /* Save user GP */
ori gp, ra, 0 /* GP now points to _registers */
calli save_all
calli handle_debug_trap
bi _b_restore_and_return
_data_bus_error_handler:
ori r0, ra, 0 /* Save RA before destroying it */
calli _find4
_find4: addi ra, ra, _registers-_find4 /* RA now points to _registers */
sw (ra+_gp-_registers), gp /* Save user GP */
ori gp, ra, 0 /* GP now points to _registers */
calli save_all
calli handle_debug_trap
bi _e_restore_and_return
_divide_by_zero_handler:
ori r0, ra, 0 /* Save RA before destroying it */
calli _find5
_find5: addi ra, ra, _registers-_find5 /* RA now points to _registers */
sw (ra+_gp-_registers), gp /* Save user GP */
ori gp, ra, 0 /* GP now points to _registers */
calli save_all
calli handle_debug_trap
bi _e_restore_and_return
_interrupt_handler:
ori r0, ra, 0 /* Save RA before destroying it */
calli _find6
_find6: addi ra, ra, _registers-_find6 /* RA now points to _registers */
sw (ra+_gp-_registers), gp /* Save user GP */
ori gp, ra, 0 /* GP now points to _registers */
calli save_all
calli handle_debug_trap
bi _e_restore_and_return
_system_call_handler:
ori r0, ra, 0 /* Save RA before destroying it */
calli _find7
_find7: addi ra, ra, _registers-_find7 /* RA now points to _registers */
sw (ra+_gp-_registers), gp /* Save user GP */
ori gp, ra, 0 /* GP now points to _registers */
calli save_all
calli handle_debug_trap
bi _e_restore_and_return
/* Restore registers and return from breakpoint */
_b_restore_and_return:
/* first restore gp registers */
calli restore_gp
/* load the last two registers */
lw ra, (gp+_ra-_registers)
lw gp, (gp+_gp-_registers)
bret
/* Restore registers and chain execution to the user exception handler */
_e_restore_and_return:
/* first restore gp registers */
calli restore_gp
lw ba, (gp+_eid-_registers)
rcsr ra, EBA
add ba, ba, ra
/* load the last two registers */
lw ra, (gp+_ra-_registers)
lw gp, (gp+_gp-_registers)
b ba
save_all:
/* Save registers */
sw (gp+_r1 -_registers), r1
sw (gp+_r2 -_registers), r2
sw (gp+_r3 -_registers), r3
sw (gp+_r4 -_registers), r4
sw (gp+_r5 -_registers), r5
sw (gp+_r6 -_registers), r6
sw (gp+_r7 -_registers), r7
sw (gp+_r8 -_registers), r8
sw (gp+_r9 -_registers), r9
sw (gp+_r10-_registers), r10
sw (gp+_r11-_registers), r11
sw (gp+_r12-_registers), r12
sw (gp+_r13-_registers), r13
sw (gp+_r14-_registers), r14
sw (gp+_r15-_registers), r15
sw (gp+_r16-_registers), r16
sw (gp+_r17-_registers), r17
sw (gp+_r18-_registers), r18
sw (gp+_r19-_registers), r19
sw (gp+_r20-_registers), r20
sw (gp+_r21-_registers), r21
sw (gp+_r22-_registers), r22
sw (gp+_r23-_registers), r23
sw (gp+_r24-_registers), r24
sw (gp+_r25-_registers), r25
/* GP already saved by handler */
sw (gp+_fp -_registers), fp
sw (gp+_sp -_registers), sp
sw (gp+_ra -_registers), r0 /* handler saved RA in R0 */
sw (gp+_ea -_registers), ea
sw (gp+_ba -_registers), ba
/* Calculate EID*32 = ra - _eid_offset */
sub r1, ra, gp
addi r1, r1, _registers-_eid_offset
sw (gp+_eid-_registers), r1
/* Start saving the CSRs */
rcsr r1, EBA
sw (gp+_eba-_registers), r1
rcsr r1, DEBA
sw (gp+_deba-_registers), r1
rcsr r1, IE
sw (gp+_ie-_registers), r1
rcsr r1, IM
sw (gp+_im-_registers), r1
rcsr r1, IP
sw (gp+_ip-_registers), r1
rcsr r1, CC
sw (gp+_cc-_registers), r1
rcsr r1, CFG
sw (gp+_cfg-_registers), r1
/* Prep R0 for normal work */
xor r0, r0, r0
ret
/* Restore gp registers */
restore_gp:
/* Write CSRs */
lw r1, (gp + _eba-_registers)
wcsr EBA, r1
lw r1, (gp + _deba-_registers)
wcsr DEBA, r1
lw r1, (gp + _ie-_registers)
wcsr IE, r1
lw r1, (gp + _im-_registers)
wcsr IM, r1
lw r1, (gp + _dc-_registers)
wcsr DC, r1
lw r1, (gp + _bp0-_registers)
wcsr BP0, r1
lw r1, (gp + _bp1-_registers)
wcsr BP1, r1
lw r1, (gp + _bp2-_registers)
wcsr BP2, r1
lw r1, (gp + _bp3-_registers)
wcsr BP3, r1
lw r1, (gp + _wp0-_registers)
wcsr WP0, r1
lw r1, (gp + _wp1-_registers)
wcsr WP1, r1
lw r1, (gp + _wp2-_registers)
wcsr WP2, r1
lw r1, (gp + _wp3-_registers)
wcsr WP3, r1
/* Write registers */
lw r1, (gp+_r1 -_registers)
lw r2, (gp+_r2 -_registers)
lw r3, (gp+_r3 -_registers)
lw r4, (gp+_r4 -_registers)
lw r5, (gp+_r5 -_registers)
lw r6, (gp+_r6 -_registers)
lw r7, (gp+_r7 -_registers)
lw r8, (gp+_r8 -_registers)
lw r9, (gp+_r9 -_registers)
lw r10, (gp+_r10-_registers)
lw r11, (gp+_r11-_registers)
lw r12, (gp+_r12-_registers)
lw r13, (gp+_r13-_registers)
lw r14, (gp+_r14-_registers)
lw r15, (gp+_r15-_registers)
lw r16, (gp+_r16-_registers)
lw r17, (gp+_r17-_registers)
lw r18, (gp+_r18-_registers)
lw r19, (gp+_r19-_registers)
lw r20, (gp+_r20-_registers)
lw r21, (gp+_r21-_registers)
lw r22, (gp+_r22-_registers)
lw r23, (gp+_r23-_registers)
lw r24, (gp+_r24-_registers)
lw r25, (gp+_r25-_registers)
/* Restore GP later */
lw fp, (gp+_fp -_registers)
/* Restore RA later */
lw sp, (gp+_sp -_registers)
lw ea, (gp+_ea -_registers)
lw ba, (gp+_ba -_registers)
ret
jtag_get_byte:
rcsr r2, JRX
andi r1, r2, 0x100
be r1, r0, jtag_get_byte
wcsr JRX, r0
andi r1, r2, 0xff
ret
jtag_get_word:
ori r27, ra, 0
calli jtag_get_byte
sb (gp+_scratch-_registers+0), r1
calli jtag_get_byte
sb (gp+_scratch-_registers+1), r1
calli jtag_get_byte
sb (gp+_scratch-_registers+2), r1
calli jtag_get_byte
sb (gp+_scratch-_registers+3), r1
lw r1, (gp+_scratch-_registers)
ori ra, r27, 0
ret
jtag_put_byte:
rcsr r2, JTX
bne r2, r0, jtag_put_byte
andi r2, r1, 0xff
wcsr JTX, r2
ret
jtag_put_word:
ori r27, ra, 0
sw (gp+_scratch-_registers), r1
lbu r1, (gp+_scratch-_registers+0)
calli jtag_put_byte
lbu r1, (gp+_scratch-_registers+1)
calli jtag_put_byte
lbu r1, (gp+_scratch-_registers+2)
calli jtag_put_byte
lbu r1, (gp+_scratch-_registers+3)
calli jtag_put_byte
ori ra, r27, 0
ret
handle_debug_trap:
ori r28, ra, 0
/* Report the debug ROM version */
mvi r1, 0x80 + 'B'
calli jtag_put_byte
_get_command:
/* Input: [Wxxxxxxx]
* W=0, x=0: quit debug trap
* W=1, x=0: report register dump location
* W=0, x>0: read 'x' bytes
* W=1, x>0: write 'x' bytes
*/
calli jtag_get_byte
be r1, r0, _done_debug_trap
/* Setup args: r10=write, r11=base, r12=length */
andi r10, r1, 0x80
andi r12, r1, 0x7f
be r12, r0, _read_registers
/* Load memory access address */
calli jtag_get_word
mv r11, r1
/* Either read or write */
bne r10, r0, _read_mem
_write_mem:
be r12, r0, _write_end
calli jtag_get_byte
sb (r11+0), r1
addi r11, r11, 1
addi r12, r12, -1
bi _write_mem
_write_end:
bi _get_command
_read_mem:
be r12, r0, _read_end
lbu r1, (r11+0)
calli jtag_put_byte
addi r11, r11, 1
addi r12, r12, -1
bi _read_mem
_read_end:
bi _get_command
_read_registers:
/* Report the offset of the registers */
mv r1, gp
calli jtag_put_word
bi _get_command
_done_debug_trap:
wcsr DCC, r0
wcsr ICC, r0
nop
nop
nop
nop
ori ra, r28, 0
ret
_registers:
_r0: /* Never used */
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_r1:
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_r2:
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_r3:
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_r4:
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_r5:
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_r6:
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_r7:
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_r8:
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_r9:
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_r10:
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_r11:
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_r12:
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_r13:
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_r14:
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_r15:
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_r16:
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_r17:
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_r18:
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_r19:
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_r20:
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_r21:
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_r22:
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_r23:
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_r24:
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_r25:
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_gp:
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_fp:
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_sp:
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_ra:
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_ea:
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_ba:
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/* Never used -- but matches gdb layout (filled in by lm32-rom.cpp) */
_pc:
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/* What exception happened *32 */
_eid:
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/* CSRs */
_eba: /* RW */
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_deba: /* RW */
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_ie: /* RW */
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_im: /* RW */
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_ip: /* R */
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/* ICC and DCC flushed on continue */
_cc: /* R */
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_cfg: /* R */
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_dc: /* W */
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/* JTX and JRX used by ROM */
_bp0: /* W */
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_bp1: /* W */
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_bp2: /* W */
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_bp3: /* W */
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_wp0: /* W */
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_wp1: /* W */
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_wp2: /* W */
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_wp3: /* W */
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/* used for assembling a word from bytes */
_scratch:
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