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ARM: 7861/1: cacheflush: consolidate single-CPU ARMv7 cache disabling code

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This code is becoming duplicated in many places.  So let's consolidate
it into a handy macro that is known to be right and available for reuse.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Nicolas Pitre 2013-10-18 22:06:03 +01:00 • committed by Russell King
parent 3c8828f6a0
commit 39792c7cf3
3 changed files with 52 additions and 98 deletions
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46
arch/arm/include/asm/cacheflush.h
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@ -435,4 +435,50 @@ static inline void __sync_cache_range_r(volatile void *p, size_t size)
#define sync_cache_w(ptr) __sync_cache_range_w(ptr, sizeof *(ptr))
#define sync_cache_r(ptr) __sync_cache_range_r(ptr, sizeof *(ptr))
/*
* Disabling cache access for one CPU in an ARMv7 SMP system is tricky.
* To do so we must:
*
* - Clear the SCTLR.C bit to prevent further cache allocations
* - Flush the desired level of cache
* - Clear the ACTLR "SMP" bit to disable local coherency
*
* ... and so without any intervening memory access in between those steps,
* not even to the stack.
*
* WARNING -- After this has been called:
*
* - No ldrex/strex (and similar) instructions must be used.
* - The CPU is obviously no longer coherent with the other CPUs.
* - This is unlikely to work as expected if Linux is running non-secure.
*
* Note:
*
* - This is known to apply to several ARMv7 processor implementations,
* however some exceptions may exist. Caveat emptor.
*
* - The clobber list is dictated by the call to v7_flush_dcache_*.
* fp is preserved to the stack explicitly prior disabling the cache
* since adding it to the clobber list is incompatible with having
* CONFIG_FRAME_POINTER=y. ip is saved as well if ever r12-clobbering
* trampoline are inserted by the linker and to keep sp 64-bit aligned.
*/
#define v7_exit_coherency_flush(level) \
asm volatile( \
"stmfd sp!, {fp, ip} \n\t" \
"mrc p15, 0, r0, c1, c0, 0 @ get SCTLR \n\t" \
"bic r0, r0, #"__stringify(CR_C)" \n\t" \
"mcr p15, 0, r0, c1, c0, 0 @ set SCTLR \n\t" \
"isb \n\t" \
"bl v7_flush_dcache_"__stringify(level)" \n\t" \
"clrex \n\t" \
"mrc p15, 0, r0, c1, c0, 1 @ get ACTLR \n\t" \
"bic r0, r0, #(1 << 6) @ disable local coherency \n\t" \
"mcr p15, 0, r0, c1, c0, 1 @ set ACTLR \n\t" \
"isb \n\t" \
"dsb \n\t" \
"ldmfd sp!, {fp, ip}" \
: : : "r0","r1","r2","r3","r4","r5","r6","r7", \
"r9","r10","lr","memory" )
#endif