[ARM] 3541/2: workaround for PXA27x erratum E7
Patch from Nicolas Pitre According to the Intel PXA27x Processor Family Specification Update document (doc.nr. 280071-009) erratum E7, some care must be taken to locate the disabling and re-enabling of the MMU to the beginning of a cache line to avoid problems in some circumstances. Credits to Simon Vogl <simon.vogl@researchstudios.at> for bringing this up. Signed-off-by: Nicolas Pitre <nico@cam.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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@ -448,8 +448,11 @@ __common_mmu_cache_on:
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mov r1, #-1
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mcr p15, 0, r3, c2, c0, 0 @ load page table pointer
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mcr p15, 0, r1, c3, c0, 0 @ load domain access control
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mcr p15, 0, r0, c1, c0, 0 @ load control register
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mov pc, lr
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b 1f
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.align 5 @ cache line aligned
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1: mcr p15, 0, r0, c1, c0, 0 @ load control register
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mrc p15, 0, r0, c1, c0, 0 @ and read it back to
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sub pc, lr, r0, lsr #32 @ properly flush pipeline
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/*
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* All code following this line is relocatable. It is relocated by
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@ -138,17 +138,23 @@ ENTRY(cpu_xscale_proc_fin)
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* to what would be the reset vector.
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*
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* loc: location to jump to for soft reset
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*
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* Beware PXA270 erratum E7.
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*/
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.align 5
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ENTRY(cpu_xscale_reset)
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mov r1, #PSR_F_BIT|PSR_I_BIT|SVC_MODE
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msr cpsr_c, r1 @ reset CPSR
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mcr p15, 0, r1, c10, c4, 1 @ unlock I-TLB
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mcr p15, 0, r1, c8, c5, 0 @ invalidate I-TLB
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mrc p15, 0, r1, c1, c0, 0 @ ctrl register
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bic r1, r1, #0x0086 @ ........B....CA.
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bic r1, r1, #0x3900 @ ..VIZ..S........
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sub pc, pc, #4 @ flush pipeline
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@ *** cache line aligned ***
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mcr p15, 0, r1, c1, c0, 0 @ ctrl register
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mcr p15, 0, ip, c7, c7, 0 @ invalidate I,D caches & BTB
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bic r1, r1, #0x0001 @ ...............M
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mcr p15, 0, ip, c7, c7, 0 @ invalidate I,D caches & BTB
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mcr p15, 0, r1, c1, c0, 0 @ ctrl register
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@ CAUTION: MMU turned off from this point. We count on the pipeline
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@ already containing those two last instructions to survive.
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