MPC5200: workaround data corruption for unaligned local bus accesses
The MPC5200 has a nasty problem that will cause silent data corruption when performing unaligned 16 or 32 byte accesses when reading from the local bus - typically this affects reading from flash. The problem can be easily shown: => md fc0c0000 10 fc0c0000: 323e4337 01626f6f 74636d64 3d72756e 2>C7.bootcmd=run fc0c0010: 206e6574 5f6e6673 00626f6f 7464656c net_nfs.bootdel fc0c0020: 61793d35 00626175 64726174 653d3131 ay=5.baudrate=11 fc0c0030: 35323030 00707265 626f6f74 3d656368 5200.preboot=ech => md fc0c0001 10 fc0c0001: 65636801 00000074 0000003d 00000020 ech....t...=... fc0c0011: 0000005f 00000000 00000074 00000061 ..._.......t...a fc0c0021: 00000000 00000064 00000065 00000035 .......d...e...5 fc0c0031: 00000000 00000062 0000003d 0000006f .......b...=...o => md.w fc0c0001 10 fc0c0001: 0000 3701 0000 6f74 0000 643d 0000 6e20 ..7...ot..d=..n fc0c0011: 0000 745f 0000 7300 0000 6f74 0000 6c61 ..t_..s...ot..la This commit implements a workaround at least for the most blatant problem: using memcpy() from NOR flash. We rename the assembler routine into __memcpy() and provide a wrapper, which will use a byte-wise copy loop for unaligned source or target addresses when reading from NOR flash, and branch to the optimized __memcpy() in all other cases, thus minimizing the performance impact. Tested on lite5200b and TQM5200S. Signed-off-by: Wolfgang Denk <wd@denx.de> Cc: Detlev Zundel <dzu@denx.de>
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@ -30,6 +30,11 @@ SOBJS = io.o firmware_sc_task_bestcomm.impl.o
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COBJS = i2c.o traps.o cpu.o cpu_init.o ide.o interrupts.o \
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loadtask.o pci_mpc5200.o serial.o speed.o usb_ohci.o usb.o
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# Workaround for local bus unaligned access problem on MPC5200
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#ifdef CONFIG_MPC5200
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COBJS += memcpy_mpc5200.o
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#endif
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SRCS := $(START:.o=.S) $(SOBJS:.o=.S) $(COBJS:.o=.c)
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OBJS := $(addprefix $(obj),$(SOBJS) $(COBJS))
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START := $(addprefix $(obj),$(START))
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71
arch/powerpc/cpu/mpc5xxx/memcpy_mpc5200.c
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71
arch/powerpc/cpu/mpc5xxx/memcpy_mpc5200.c
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@ -0,0 +1,71 @@
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/*
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* (C) Copyright 2010
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* Wolfgang Denk, DENX Software Engineering, wd@denx.de.
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*
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* See file CREDITS for list of people who contributed to this
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* project.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
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* MA 02111-1307 USA
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*/
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/*
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* This is a workaround for issues on the MPC5200, where unaligned
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* 32-bit-accesses to the local bus will deliver corrupted data. This
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* happens for example when trying to use memcpy() from an odd NOR
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* flash address; the behaviour can be also seen when using "md" on an
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* odd NOR flash address (but there it is not a bug in U-Boot, which
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* only shows the behaviour of this processor).
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*
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* For memcpy(), we test if either the source or the target address
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* are not 32 bit aligned, and - if so - if the source address is in
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* NOR flash: in this case we perform a byte-wise (slow) then; for
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* aligned operations of non-flash areas we use the optimized (fast)
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* real __memcpy(). This way we minimize the performance impact of
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* this workaround.
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*
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*/
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#include <common.h>
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#include <flash.h>
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#include <linux/types.h>
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void *memcpy(void *trg, const void *src, size_t len)
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{
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extern void* __memcpy(void *, const void *, size_t);
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char *s = (char *)src;
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char *t = (char *)trg;
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void *dest = (void *)src;
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/*
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* Check is source address is in flash:
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* If not, we use the fast assembler code
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*/
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if (((((unsigned long)s & 3) == 0) /* source aligned */
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&& /* AND */
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(((unsigned long)t & 3) == 0)) /* target aligned, */
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|| /* or */
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(addr2info((ulong)s) == NULL)) { /* source not in flash */
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return __memcpy(trg, src, len);
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}
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/*
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* Copying from flash, perform byte by byte copy.
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*/
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while (len-- > 0)
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*t++ = *s++;
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return dest;
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}
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@ -43,6 +43,11 @@ COBJS-y += time.o
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SRCS := $(SOBJS-y:.o=.S) $(COBJS-y:.o=.c)
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OBJS := $(addprefix $(obj),$(SOBJS-y) $(COBJS-y))
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# Workaround for local bus unaligned access problem on MPC5200
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ifdef CONFIG_MPC5200
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$(obj)ppcstring.o: AFLAGS += -Dmemcpy=__memcpy
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endif
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$(LIB): $(obj).depend $(OBJS)
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@if ! $(CROSS_COMPILE)readelf -S $(OBJS) | grep -q '\.fixup.*PROGBITS';\
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then \
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