libc/libgloss/mips/vr5xxx.S

458 lines
12 KiB
ArmAsm

/*
* vr5xxx.S -- CPU specific support routines
*
* Copyright (c) 1999 Cygnus Solutions
*
* The authors hereby grant permission to use, copy, modify, distribute,
* and license this software and its documentation for any purpose, provided
* that existing copyright notices are retained in all copies and that this
* notice is included verbatim in any distributions. No written agreement,
* license, or royalty fee is required for any of the authorized uses.
* Modifications to this software may be copyrighted by their authors
* and need not follow the licensing terms described here, provided that
* the new terms are clearly indicated on the first page of each file where
* they apply.
*/
/* This file cloned from vr4300.S by dlindsay@cygnus.com
* and recoded to suit Vr5432 and Vr5000.
* Should be no worse for Vr43{00,05,10}.
* Specifically, __cpu_flush() has been changed (a) to allow for the hardware
* difference (in set associativity) between the Vr5432 and Vr5000,
* and (b) to flush the optional secondary cache of the Vr5000.
*/
/* Processor Revision Identifier (PRID) Register: Implementation Numbers */
#define IMPL_VR5432 0x54
/* Cache Constants not determinable dynamically */
#define VR5000_2NDLINE 32 /* secondary cache line size */
#define VR5432_LINE 32 /* I,Dcache line sizes */
#define VR5432_SIZE (16*1024) /* I,Dcache half-size */
#ifndef __mips64
.set mips3
#endif
#ifdef __mips16
/* This file contains 32 bit assembly code. */
.set nomips16
#endif
#include "regs.S"
.text
.align 2
# Taken from "R4300 Preliminary RISC Processor Specification
# Revision 2.0 January 1995" page 39: "The Count
# register... increments at a constant rate... at one-half the
# PClock speed."
# We can use this fact to provide small polled delays.
.globl __cpu_timer_poll
.ent __cpu_timer_poll
__cpu_timer_poll:
.set noreorder
# in: a0 = (unsigned int) number of PClock ticks to wait for
# out: void
# The Vr4300 counter updates at half PClock, so divide by 2 to
# get counter delta:
bnezl a0, 1f # continue if delta non-zero
srl a0, a0, 1 # divide ticks by 2 {DELAY SLOT}
# perform a quick return to the caller:
j ra
nop # {DELAY SLOT}
1:
mfc0 v0, C0_COUNT # get current counter value
nop
nop
# We cannot just do the simple test, of adding our delta onto
# the current value (ignoring overflow) and then checking for
# equality. The counter is incrementing every two PClocks,
# which means the counter value can change between
# instructions, making it hard to sample at the exact value
# desired.
# However, we do know that our entry delta value is less than
# half the number space (since we divide by 2 on entry). This
# means we can use a difference in signs to indicate timer
# overflow.
addu a0, v0, a0 # unsigned add (ignore overflow)
# We know have our end value (which will have been
# sign-extended to fill the 64bit register value).
2:
# get current counter value:
mfc0 v0, C0_COUNT
nop
nop
# This is an unsigned 32bit subtraction:
subu v0, a0, v0 # delta = (end - now) {DELAY SLOT}
bgtzl v0, 2b # looping back is most likely
nop
# We have now been delayed (in the foreground) for AT LEAST
# the required number of counter ticks.
j ra # return to caller
nop # {DELAY SLOT}
.set reorder
.end __cpu_timer_poll
# Flush the processor caches to memory:
.globl __cpu_flush
.ent __cpu_flush
__cpu_flush:
.set noreorder
# NOTE: The Vr4300 and Vr5432 *CANNOT* have any secondary cache.
# On those, SC (bit 17 of CONFIG register) is hard-wired to 1,
# except that email from Dennis_Han@el.nec.com says that old
# versions of the Vr5432 incorrectly hard-wired this bit to 0.
# The Vr5000 has an optional direct-mapped secondary cache,
# and the SC bit correctly indicates this.
# So, for the 4300 and 5432 we want to just
# flush the primary Data and Instruction caches.
# For the 5000 it is desired to flush the secondary cache too.
# There is an operation difference worth noting.
# The 4300 and 5000 primary caches use VA bit 14 to choose cache set,
# whereas 5432 primary caches use VA bit 0.
# This code interprets the relevant Config register bits as
# much as possible, except for the 5432.
# The code therefore has some portability.
# However, the associativity issues mean you should not just assume
# that this code works anywhere. Also, the secondary cache set
# size is hardwired, since the 5000 series does not define codes
# for variant sizes.
# Note: this version of the code flushes D$ before I$.
# It is difficult to construct a case where that matters,
# but it cant hurt.
mfc0 a0, C0_PRID # a0 = Processor Revision register
nop # dlindsay: unclear why the nops, but
nop # vr4300.S had such so I do too.
srl a2, a0, PR_IMP # want bits 8..15
andi a2, a2, 0x255 # mask: now a2 = Implementation # field
li a1, IMPL_VR5432
beq a1, a2, 8f # use Vr5432-specific flush algorithm
nop
# Non-Vr5432 version of the code.
# (The distinctions being: CONFIG is truthful about secondary cache,
# and we act as if the primary Icache and Dcache are direct mapped.)
mfc0 t0, C0_CONFIG # t0 = CONFIG register
nop
nop
li a1, 1 # a1=1, a useful constant
srl a2, t0, CR_IC # want IC field of CONFIG
andi a2, a2, 0x7 # mask: now a2= code for Icache size
add a2, a2, 12 # +12
sllv a2, a1, a2 # a2=primary instruction cache size in bytes
srl a3, t0, CR_DC # DC field of CONFIG
andi a3, a3, 0x7 # mask: now a3= code for Dcache size
add a3, a3, 12 # +12
sllv a3, a1, a3 # a3=primary data cache size in bytes
li t2, (1 << CR_IB) # t2=mask over IB boolean
and t2, t2, t0 # test IB field of CONFIG register value
beqz t2, 1f #
li a1, 16 # 16 bytes (branch shadow: always loaded.)
li a1, 32 # non-zero, then 32bytes
1:
li t2, (1 << CR_DB) # t2=mask over DB boolean
and t2, t2, t0 # test BD field of CONFIG register value
beqz t2, 2f #
li a0, 16 # 16bytes (branch shadow: always loaded.)
li a0, 32 # non-zero, then 32bytes
2:
lui t1, ((K0BASE >> 16) & 0xFFFF)
ori t1, t1, (K0BASE & 0xFFFF)
# At this point,
# a0 = primary Dcache line size in bytes
# a1 = primary Icache line size in bytes
# a2 = primary Icache size in bytes
# a3 = primary Dcache size in bytes
# t0 = CONFIG value
# t1 = a round unmapped cached base address (we are in kernel mode)
# t2,t3 scratch
addi t3, t1, 0 # t3=t1=start address for any cache
add t2, t3, a3 # t2=end adress+1 of Dcache
sub t2, t2, a0 # t2=address of last line in Dcache
3:
cache INDEX_WRITEBACK_INVALIDATE_D,0(t3)
bne t3, t2, 3b #
addu t3, a0 # (delay slot) increment by Dcache line size
# Now check CONFIG to see if there is a secondary cache
lui t2, (1 << (CR_SC-16)) # t2=mask over SC boolean
and t2, t2, t0 # test SC in CONFIG
bnez t2, 6f
# There is a secondary cache. Find out its sizes.
srl t3, t0, CR_SS # want SS field of CONFIG
andi t3, t3, 0x3 # mask: now t3= code for cache size.
beqz t3, 4f
lui a3, ((512*1024)>>16) # a3= 512K, code was 0
addu t3, -1 # decrement code
beqz t3, 4f
lui a3, ((1024*1024)>>16) # a3= 1 M, code 1
addu t3, -1 # decrement code
beqz t3, 4f
lui a3, ((2*1024*1024)>>16) # a3= 2 M, code 2
j 6f # no secondary cache, code 3
4: # a3 = secondary cache size in bytes
li a0, VR5000_2NDLINE # no codes assigned for other than 32
# At this point,
# a0 = secondary cache line size in bytes
# a1 = primary Icache line size in bytes
# a2 = primary Icache size in bytes
# a3 = secondary cache size in bytes
# t1 = a round unmapped cached base address (we are in kernel mode)
# t2,t3 scratch
addi t3, t1, 0 # t3=t1=start address for any cache
add t2, t3, a3 # t2=end address+1 of secondary cache
sub t2, t2, a0 # t2=address of last line in secondary cache
5:
cache INDEX_WRITEBACK_INVALIDATE_SD,0(t3)
bne t3, t2, 5b
addu t3, a0 # (delay slot) increment by line size
6: # Any optional secondary cache done. Now do I-cache and return.
# At this point,
# a1 = primary Icache line size in bytes
# a2 = primary Icache size in bytes
# t1 = a round unmapped cached base address (we are in kernel mode)
# t2,t3 scratch
add t2, t1, a2 # t2=end adress+1 of Icache
sub t2, t2, a1 # t2=address of last line in Icache
7:
cache INDEX_INVALIDATE_I,0(t1)
bne t1, t2, 7b
addu t1, a1 # (delay slot) increment by Icache line size
j ra # return to the caller
nop
8:
# Vr5432 version of the cpu_flush code.
# (The distinctions being: CONFIG can not be trusted about secondary
# cache (which does not exist). The primary caches use Virtual Address Bit 0
# to control set selection.
# Code does not consult CONFIG about cache sizes: knows the hardwired sizes.
# Since both I and D have the same size and line size, uses a merged loop.
li a0, VR5432_LINE
li a1, VR5432_SIZE
lui t1, ((K0BASE >> 16) & 0xFFFF)
ori t1, t1, (K0BASE & 0xFFFF)
# a0 = cache line size in bytes
# a1 = 1/2 cache size in bytes
# t1 = a round unmapped cached base address (we are in kernel mode)
add t2, t1, a1 # t2=end address+1
sub t2, t2, a0 # t2=address of last line in Icache
9:
cache INDEX_WRITEBACK_INVALIDATE_D,0(t1) # set 0
cache INDEX_WRITEBACK_INVALIDATE_D,1(t1) # set 1
cache INDEX_INVALIDATE_I,0(t1) # set 0
cache INDEX_INVALIDATE_I,1(t1) # set 1
bne t1, t2, 9b
addu t1, a0
j ra # return to the caller
nop
.set reorder
.end __cpu_flush
# NOTE: This variable should *NOT* be addressed relative to
# the $gp register since this code is executed before $gp is
# initialised... hence we leave it in the text area. This will
# cause problems if this routine is ever ROMmed:
.globl __buserr_cnt
__buserr_cnt:
.word 0
.align 3
__k1_save:
.word 0
.word 0
.align 2
.ent __buserr
.globl __buserr
__buserr:
.set noat
.set noreorder
# k0 and k1 available for use:
mfc0 k0,C0_CAUSE
nop
nop
andi k0,k0,0x7c
sub k0,k0,7 << 2
beq k0,$0,__buserr_do
nop
# call the previous handler
la k0,__previous
jr k0
nop
#
__buserr_do:
# TODO: check that the cause is indeed a bus error
# - if not then just jump to the previous handler
la k0,__k1_save
sd k1,0(k0)
#
la k1,__buserr_cnt
lw k0,0(k1) # increment counter
addu k0,1
sw k0,0(k1)
#
la k0,__k1_save
ld k1,0(k0)
#
mfc0 k0,C0_EPC
nop
nop
addu k0,k0,4 # skip offending instruction
mtc0 k0,C0_EPC # update EPC
nop
nop
eret
# j k0
# rfe
.set reorder
.set at
.end __buserr
__exception_code:
.set noreorder
lui k0,%hi(__buserr)
daddiu k0,k0,%lo(__buserr)
jr k0
nop
.set reorder
__exception_code_end:
.data
__previous:
.space (__exception_code_end - __exception_code)
# This subtracting two addresses is working
# but is not garenteed to continue working.
# The assemble reserves the right to put these
# two labels into different frags, and then
# cant take their difference.
.text
.ent __default_buserr_handler
.globl __default_buserr_handler
__default_buserr_handler:
.set noreorder
# attach our simple bus error handler:
# in: void
# out: void
mfc0 a0,C0_SR
nop
li a1,SR_BEV
and a1,a1,a0
beq a1,$0,baseaddr
lui a0,0x8000 # delay slot
lui a0,0xbfc0
daddiu a0,a0,0x0200
baseaddr:
daddiu a0,a0,0x0180
# a0 = base vector table address
la a1,__exception_code_end
la a2,__exception_code
subu a1,a1,a2
la a3,__previous
# there must be a better way of doing this????
copyloop:
lw v0,0(a0)
sw v0,0(a3)
lw v0,0(a2)
sw v0,0(a0)
daddiu a0,a0,4
daddiu a2,a2,4
daddiu a3,a3,4
subu a1,a1,4
bne a1,$0,copyloop
nop
la a0,__buserr_cnt
sw $0,0(a0)
j ra
nop
.set reorder
.end __default_buserr_handler
.ent __restore_buserr_handler
.globl __restore_buserr_handler
__restore_buserr_handler:
.set noreorder
# restore original (monitor) bus error handler
# in: void
# out: void
mfc0 a0,C0_SR
nop
li a1,SR_BEV
and a1,a1,a0
beq a1,$0,res_baseaddr
lui a0,0x8000 # delay slot
lui a0,0xbfc0
daddiu a0,a0,0x0200
res_baseaddr:
daddiu a0,a0,0x0180
# a0 = base vector table address
la a1,__exception_code_end
la a3,__exception_code
subu a1,a1,a3
la a3,__previous
# there must be a better way of doing this????
res_copyloop:
lw v0,0(a3)
sw v0,0(a0)
daddiu a0,a0,4
daddiu a3,a3,4
subu a1,a1,4
bne a1,$0,res_copyloop
nop
j ra
nop
.set reorder
.end __restore_buserr_handler
.ent __buserr_count
.globl __buserr_count
__buserr_count:
.set noreorder
# restore original (monitor) bus error handler
# in: void
# out: unsigned int __buserr_cnt
la v0,__buserr_cnt
lw v0,0(v0)
j ra
nop
.set reorder
.end __buserr_count
/* EOF vr5xxx.S */