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linux-pinenote/arch/arm/mm/cache-v4wb.S
Lorenzo Pieralisi 031bd879f7 ARM: mm: implement LoUIS API for cache maintenance ops 
ARM v7 architecture introduced the concept of cache levels and related
control registers. New processors like A7 and A15 embed an L2 unified cache
controller that becomes part of the cache level hierarchy. Some operations in
the kernel like cpu_suspend and __cpu_disable do not require a flush of the
entire cache hierarchy to DRAM but just the cache levels belonging to the
Level of Unification Inner Shareable (LoUIS), which in most of ARM v7 systems
correspond to L1.

The current cache flushing API used in cpu_suspend and __cpu_disable,
flush_cache_all(), ends up flushing the whole cache hierarchy since for
v7 it cleans and invalidates all cache levels up to Level of Coherency
(LoC) which cripples system performance when used in hot paths like hotplug
and cpuidle.

Therefore a new kernel cache maintenance API must be added to cope with
latest ARM system requirements.

This patch adds flush_cache_louis() to the ARM kernel cache maintenance API.

This function cleans and invalidates all data cache levels up to the
Level of Unification Inner Shareable (LoUIS) and invalidates the instruction
cache for processors that support it (> v7).

This patch also creates an alias of the cache LoUIS function to flush_kern_all
for all processor versions prior to v7, so that the current cache flushing
behaviour is unchanged for those processors.

v7 cache maintenance code implements a cache LoUIS function that cleans and
invalidates the D-cache up to LoUIS and invalidates the I-cache, according
to the new API.

Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Reviewed-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Tested-by: Shawn Guo <shawn.guo@linaro.org>
2012-09-25 11:20:25 +01:00

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/*
* linux/arch/arm/mm/cache-v4wb.S
*
* Copyright (C) 1997-2002 Russell king
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/linkage.h>
#include <linux/init.h>
#include <asm/memory.h>
#include <asm/page.h>
#include "proc-macros.S"
/*
* The size of one data cache line.
*/
#define CACHE_DLINESIZE 32
/*
* The total size of the data cache.
*/
#if defined(CONFIG_CPU_SA110)
# define CACHE_DSIZE 16384
#elif defined(CONFIG_CPU_SA1100)
# define CACHE_DSIZE 8192
#else
# error Unknown cache size
#endif
/*
* This is the size at which it becomes more efficient to
* clean the whole cache, rather than using the individual
* cache line maintenance instructions.
*
* Size Clean (ticks) Dirty (ticks)
* 4096 21 20 21 53 55 54
* 8192 40 41 40 106 100 102
* 16384 77 77 76 140 140 138
* 32768 150 149 150 214 216 212 <---
* 65536 296 297 296 351 358 361
* 131072 591 591 591 656 657 651
* Whole 132 136 132 221 217 207 <---
*/
#define CACHE_DLIMIT (CACHE_DSIZE * 4)
.data
flush_base:
.long FLUSH_BASE
.text
/*
* flush_icache_all()
*
* Unconditionally clean and invalidate the entire icache.
*/
ENTRY(v4wb_flush_icache_all)
mov r0, #0
mcr p15, 0, r0, c7, c5, 0 @ invalidate I cache
mov pc, lr
ENDPROC(v4wb_flush_icache_all)
/*
* flush_user_cache_all()
*
* Clean and invalidate all cache entries in a particular address
* space.
*/
ENTRY(v4wb_flush_user_cache_all)
/* FALLTHROUGH */
/*
* flush_kern_cache_all()
*
* Clean and invalidate the entire cache.
*/
ENTRY(v4wb_flush_kern_cache_all)
mov ip, #0
mcr p15, 0, ip, c7, c5, 0 @ invalidate I cache
__flush_whole_cache:
ldr r3, =flush_base
ldr r1, [r3, #0]
eor r1, r1, #CACHE_DSIZE
str r1, [r3, #0]
add r2, r1, #CACHE_DSIZE
1: ldr r3, [r1], #32
cmp r1, r2
blo 1b
#ifdef FLUSH_BASE_MINICACHE
add r2, r2, #FLUSH_BASE_MINICACHE - FLUSH_BASE
sub r1, r2, #512 @ only 512 bytes
1: ldr r3, [r1], #32
cmp r1, r2
blo 1b
#endif
mcr p15, 0, ip, c7, c10, 4 @ drain write buffer
mov pc, lr
/*
* flush_user_cache_range(start, end, flags)
*
* Invalidate a range of cache entries in the specified
* address space.
*
* - start - start address (inclusive, page aligned)
* - end - end address (exclusive, page aligned)
* - flags - vma_area_struct flags describing address space
*/
ENTRY(v4wb_flush_user_cache_range)
mov ip, #0
sub r3, r1, r0 @ calculate total size
tst r2, #VM_EXEC @ executable region?
mcrne p15, 0, ip, c7, c5, 0 @ invalidate I cache
cmp r3, #CACHE_DLIMIT @ total size >= limit?
bhs __flush_whole_cache @ flush whole D cache
1: mcr p15, 0, r0, c7, c10, 1 @ clean D entry
mcr p15, 0, r0, c7, c6, 1 @ invalidate D entry
add r0, r0, #CACHE_DLINESIZE
cmp r0, r1
blo 1b
tst r2, #VM_EXEC
mcrne p15, 0, ip, c7, c10, 4 @ drain write buffer
mov pc, lr
/*
* flush_kern_dcache_area(void *addr, size_t size)
*
* Ensure no D cache aliasing occurs, either with itself or
* the I cache
*
* - addr - kernel address
* - size - region size
*/
ENTRY(v4wb_flush_kern_dcache_area)
add r1, r0, r1
/* fall through */
/*
* coherent_kern_range(start, end)
*
* Ensure coherency between the Icache and the Dcache in the
* region described by start. If you have non-snooping
* Harvard caches, you need to implement this function.
*
* - start - virtual start address
* - end - virtual end address
*/
ENTRY(v4wb_coherent_kern_range)
/* fall through */
/*
* coherent_user_range(start, end)
*
* Ensure coherency between the Icache and the Dcache in the
* region described by start. If you have non-snooping
* Harvard caches, you need to implement this function.
*
* - start - virtual start address
* - end - virtual end address
*/
ENTRY(v4wb_coherent_user_range)
bic r0, r0, #CACHE_DLINESIZE - 1
1: mcr p15, 0, r0, c7, c10, 1 @ clean D entry
mcr p15, 0, r0, c7, c6, 1 @ invalidate D entry
add r0, r0, #CACHE_DLINESIZE
cmp r0, r1
blo 1b
mov r0, #0
mcr p15, 0, r0, c7, c5, 0 @ invalidate I cache
mcr p15, 0, r0, c7, c10, 4 @ drain WB
mov pc, lr
/*
* dma_inv_range(start, end)
*
* Invalidate (discard) the specified virtual address range.
* May not write back any entries. If 'start' or 'end'
* are not cache line aligned, those lines must be written
* back.
*
* - start - virtual start address
* - end - virtual end address
*/
v4wb_dma_inv_range:
tst r0, #CACHE_DLINESIZE - 1
bic r0, r0, #CACHE_DLINESIZE - 1
mcrne p15, 0, r0, c7, c10, 1 @ clean D entry
tst r1, #CACHE_DLINESIZE - 1
mcrne p15, 0, r1, c7, c10, 1 @ clean D entry
1: mcr p15, 0, r0, c7, c6, 1 @ invalidate D entry
add r0, r0, #CACHE_DLINESIZE
cmp r0, r1
blo 1b
mcr p15, 0, r0, c7, c10, 4 @ drain write buffer
mov pc, lr
/*
* dma_clean_range(start, end)
*
* Clean (write back) the specified virtual address range.
*
* - start - virtual start address
* - end - virtual end address
*/
v4wb_dma_clean_range:
bic r0, r0, #CACHE_DLINESIZE - 1
1: mcr p15, 0, r0, c7, c10, 1 @ clean D entry
add r0, r0, #CACHE_DLINESIZE
cmp r0, r1
blo 1b
mcr p15, 0, r0, c7, c10, 4 @ drain write buffer
mov pc, lr
/*
* dma_flush_range(start, end)
*
* Clean and invalidate the specified virtual address range.
*
* - start - virtual start address
* - end - virtual end address
*
* This is actually the same as v4wb_coherent_kern_range()
*/
.globl v4wb_dma_flush_range
.set v4wb_dma_flush_range, v4wb_coherent_kern_range
/*
* dma_map_area(start, size, dir)
* - start - kernel virtual start address
* - size - size of region
* - dir - DMA direction
*/
ENTRY(v4wb_dma_map_area)
add r1, r1, r0
cmp r2, #DMA_TO_DEVICE
beq v4wb_dma_clean_range
bcs v4wb_dma_inv_range
b v4wb_dma_flush_range
ENDPROC(v4wb_dma_map_area)
/*
* dma_unmap_area(start, size, dir)
* - start - kernel virtual start address
* - size - size of region
* - dir - DMA direction
*/
ENTRY(v4wb_dma_unmap_area)
mov pc, lr
ENDPROC(v4wb_dma_unmap_area)
.globl v4wb_flush_kern_cache_louis
.equ v4wb_flush_kern_cache_louis, v4wb_flush_kern_cache_all
__INITDATA
@ define struct cpu_cache_fns (see <asm/cacheflush.h> and proc-macros.S)
define_cache_functions v4wb
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