arch/arm/mm/cache-v7m.S - linux - Git at Google

 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
  *  linux/arch/arm/mm/cache-v7m.S
  *
  *  Based on linux/arch/arm/mm/cache-v7.S
  *
  *  Copyright (C) 2001 Deep Blue Solutions Ltd.
  *  Copyright (C) 2005 ARM Ltd.
  *
  *  This is the "shell" of the ARMv7M processor support.
  */
 #include <linux/linkage.h>
 #include <linux/init.h>
 #include <asm/assembler.h>
 #include <asm/errno.h>
 #include <asm/unwind.h>
 #include <asm/v7m.h>

 #include "proc-macros.S"

 /* Generic V7M read/write macros for memory mapped cache operations */
 .macro v7m_cache_read, rt, reg
 	movw	\rt, #:lower16:BASEADDR_V7M_SCB + \reg
 	movt	\rt, #:upper16:BASEADDR_V7M_SCB + \reg
 	ldr     \rt, [\rt]
 .endm

 .macro v7m_cacheop, rt, tmp, op, c = al
 	movw\c	\tmp, #:lower16:BASEADDR_V7M_SCB + \op
 	movt\c	\tmp, #:upper16:BASEADDR_V7M_SCB + \op
 	str\c	\rt, [\tmp]
 .endm


 .macro	read_ccsidr, rt
 	v7m_cache_read \rt, V7M_SCB_CCSIDR
 .endm

 .macro read_clidr, rt
 	v7m_cache_read \rt, V7M_SCB_CLIDR
 .endm

 .macro	write_csselr, rt, tmp
 	v7m_cacheop \rt, \tmp, V7M_SCB_CSSELR
 .endm

 /*
  * dcisw: Invalidate data cache by set/way
  */
 .macro dcisw, rt, tmp
 	v7m_cacheop \rt, \tmp, V7M_SCB_DCISW
 .endm

 /*
  * dccisw: Clean and invalidate data cache by set/way
  */
 .macro dccisw, rt, tmp
 	v7m_cacheop \rt, \tmp, V7M_SCB_DCCISW
 .endm

 /*
  * dccimvac: Clean and invalidate data cache line by MVA to PoC.
  */
 .irp    c,,eq,ne,cs,cc,mi,pl,vs,vc,hi,ls,ge,lt,gt,le,hs,lo
 .macro dccimvac\c, rt, tmp
 	v7m_cacheop \rt, \tmp, V7M_SCB_DCCIMVAC, \c
 .endm
 .endr

 /*
  * dcimvac: Invalidate data cache line by MVA to PoC
  */
 .irp    c,,eq,ne,cs,cc,mi,pl,vs,vc,hi,ls,ge,lt,gt,le,hs,lo
 .macro dcimvac\c, rt, tmp
 	v7m_cacheop \rt, \tmp, V7M_SCB_DCIMVAC, \c
 .endm
 .endr

 /*
  * dccmvau: Clean data cache line by MVA to PoU
  */
 .macro dccmvau, rt, tmp
 	v7m_cacheop \rt, \tmp, V7M_SCB_DCCMVAU
 .endm

 /*
  * dccmvac: Clean data cache line by MVA to PoC
  */
 .macro dccmvac,  rt, tmp
 	v7m_cacheop \rt, \tmp, V7M_SCB_DCCMVAC
 .endm

 /*
  * icimvau: Invalidate instruction caches by MVA to PoU
  */
 .macro icimvau, rt, tmp
 	v7m_cacheop \rt, \tmp, V7M_SCB_ICIMVAU
 .endm

 /*
  * Invalidate the icache, inner shareable if SMP, invalidate BTB for UP.
  * rt data ignored by ICIALLU(IS), so can be used for the address
  */
 .macro invalidate_icache, rt
 	v7m_cacheop \rt, \rt, V7M_SCB_ICIALLU
 	mov \rt, #0
 .endm

 /*
  * Invalidate the BTB, inner shareable if SMP.
  * rt data ignored by BPIALL, so it can be used for the address
  */
 .macro invalidate_bp, rt
 	v7m_cacheop \rt, \rt, V7M_SCB_BPIALL
 	mov \rt, #0
 .endm

 ENTRY(v7m_invalidate_l1)
 	mov	r0, #0

 	write_csselr r0, r1
 	read_ccsidr r0

 	movw	r1, #0x7fff
 	and	r2, r1, r0, lsr #13

 	movw	r1, #0x3ff

 	and	r3, r1, r0, lsr #3      @ NumWays - 1
 	add	r2, r2, #1              @ NumSets

 	and	r0, r0, #0x7
 	add	r0, r0, #4      @ SetShift

 	clz	r1, r3          @ WayShift
 	add	r4, r3, #1      @ NumWays
 1:	sub	r2, r2, #1      @ NumSets--
 	mov	r3, r4          @ Temp = NumWays
 2:	subs	r3, r3, #1      @ Temp--
 	mov	r5, r3, lsl r1
 	mov	r6, r2, lsl r0
 	orr	r5, r5, r6      @ Reg = (Temp<<WayShift)|(NumSets<<SetShift)
 	dcisw	r5, r6
 	bgt	2b
 	cmp	r2, #0
 	bgt	1b
 	dsb	st
 	isb
 	ret	lr
 ENDPROC(v7m_invalidate_l1)

 /*
  *	v7m_flush_icache_all()
  *
  *	Flush the whole I-cache.
  *
  *	Registers:
  *	r0 - set to 0
  */
 ENTRY(v7m_flush_icache_all)
 	invalidate_icache r0
 	ret	lr
 ENDPROC(v7m_flush_icache_all)

 /*
  *	v7m_flush_dcache_all()
  *
  *	Flush the whole D-cache.
  *
  *	Corrupted registers: r0-r7, r9-r11
  */
 ENTRY(v7m_flush_dcache_all)
 	dmb					@ ensure ordering with previous memory accesses
 	read_clidr r0
 	mov	r3, r0, lsr #23			@ move LoC into position
 	ands	r3, r3, #7 << 1			@ extract LoC*2 from clidr
 	beq	finished			@ if loc is 0, then no need to clean
 start_flush_levels:
 	mov	r10, #0				@ start clean at cache level 0
 flush_levels:
 	add	r2, r10, r10, lsr #1		@ work out 3x current cache level
 	mov	r1, r0, lsr r2			@ extract cache type bits from clidr
 	and	r1, r1, #7			@ mask of the bits for current cache only
 	cmp	r1, #2				@ see what cache we have at this level
 	blt	skip				@ skip if no cache, or just i-cache
 #ifdef CONFIG_PREEMPT
 	save_and_disable_irqs_notrace r9	@ make cssr&csidr read atomic
 #endif
 	write_csselr r10, r1			@ set current cache level
 	isb					@ isb to sych the new cssr&csidr
 	read_ccsidr r1				@ read the new csidr
 #ifdef CONFIG_PREEMPT
 	restore_irqs_notrace r9
 #endif
 	and	r2, r1, #7			@ extract the length of the cache lines
 	add	r2, r2, #4			@ add 4 (line length offset)
 	movw	r4, #0x3ff
 	ands	r4, r4, r1, lsr #3		@ find maximum number on the way size
 	clz	r5, r4				@ find bit position of way size increment
 	movw	r7, #0x7fff
 	ands	r7, r7, r1, lsr #13		@ extract max number of the index size
 loop1:
 	mov	r9, r7				@ create working copy of max index
 loop2:
 	lsl	r6, r4, r5
 	orr	r11, r10, r6			@ factor way and cache number into r11
 	lsl	r6, r9, r2
 	orr	r11, r11, r6			@ factor index number into r11
 	dccisw	r11, r6				@ clean/invalidate by set/way
 	subs	r9, r9, #1			@ decrement the index
 	bge	loop2
 	subs	r4, r4, #1			@ decrement the way
 	bge	loop1
 skip:
 	add	r10, r10, #2			@ increment cache number
 	cmp	r3, r10
 	bgt	flush_levels
 finished:
 	mov	r10, #0				@ switch back to cache level 0
 	write_csselr r10, r3			@ select current cache level in cssr
 	dsb	st
 	isb
 	ret	lr
 ENDPROC(v7m_flush_dcache_all)

 /*
  *	v7m_flush_cache_all()
  *
  *	Flush the entire cache system.
  *  The data cache flush is now achieved using atomic clean / invalidates
  *  working outwards from L1 cache. This is done using Set/Way based cache
  *  maintenance instructions.
  *  The instruction cache can still be invalidated back to the point of
  *  unification in a single instruction.
  *
  */
 ENTRY(v7m_flush_kern_cache_all)
 	stmfd	sp!, {r4-r7, r9-r11, lr}
 	bl	v7m_flush_dcache_all
 	invalidate_icache r0
 	ldmfd	sp!, {r4-r7, r9-r11, lr}
 	ret	lr
 ENDPROC(v7m_flush_kern_cache_all)

 /*
  *	v7m_flush_cache_all()
  *
  *	Flush all TLB entries in a particular address space
  *
  *	- mm    - mm_struct describing address space
  */
 ENTRY(v7m_flush_user_cache_all)
 	/*FALLTHROUGH*/

 /*
  *	v7m_flush_cache_range(start, end, flags)
  *
  *	Flush a range of TLB entries in the specified address space.
  *
  *	- start - start address (may not be aligned)
  *	- end   - end address (exclusive, may not be aligned)
  *	- flags	- vm_area_struct flags describing address space
  *
  *	It is assumed that:
  *	- we have a VIPT cache.
  */
 ENTRY(v7m_flush_user_cache_range)
 	ret	lr
 ENDPROC(v7m_flush_user_cache_all)
 ENDPROC(v7m_flush_user_cache_range)

 /*
  *	v7m_coherent_kern_range(start,end)
  *
  *	Ensure that the I and D caches are coherent within specified
  *	region.  This is typically used when code has been written to
  *	a memory region, and will be executed.
  *
  *	- start   - virtual start address of region
  *	- end     - virtual end address of region
  *
  *	It is assumed that:
  *	- the Icache does not read data from the write buffer
  */
 ENTRY(v7m_coherent_kern_range)
 	/* FALLTHROUGH */

 /*
  *	v7m_coherent_user_range(start,end)
  *
  *	Ensure that the I and D caches are coherent within specified
  *	region.  This is typically used when code has been written to
  *	a memory region, and will be executed.
  *
  *	- start   - virtual start address of region
  *	- end     - virtual end address of region
  *
  *	It is assumed that:
  *	- the Icache does not read data from the write buffer
  */
 ENTRY(v7m_coherent_user_range)
  UNWIND(.fnstart		)
 	dcache_line_size r2, r3
 	sub	r3, r2, #1
 	bic	r12, r0, r3
 1:
 /*
  * We use open coded version of dccmvau otherwise USER() would
  * point at movw instruction.
  */
 	dccmvau	r12, r3
 	add	r12, r12, r2
 	cmp	r12, r1
 	blo	1b
 	dsb	ishst
 	icache_line_size r2, r3
 	sub	r3, r2, #1
 	bic	r12, r0, r3
 2:
 	icimvau r12, r3
 	add	r12, r12, r2
 	cmp	r12, r1
 	blo	2b
 	invalidate_bp r0
 	dsb	ishst
 	isb
 	ret	lr
  UNWIND(.fnend		)
 ENDPROC(v7m_coherent_kern_range)
 ENDPROC(v7m_coherent_user_range)

 /*
  *	v7m_flush_kern_dcache_area(void *addr, size_t size)
  *
  *	Ensure that the data held in the page kaddr is written back
  *	to the page in question.
  *
  *	- addr	- kernel address
  *	- size	- region size
  */
 ENTRY(v7m_flush_kern_dcache_area)
 	dcache_line_size r2, r3
 	add	r1, r0, r1
 	sub	r3, r2, #1
 	bic	r0, r0, r3
 1:
 	dccimvac r0, r3		@ clean & invalidate D line / unified line
 	add	r0, r0, r2
 	cmp	r0, r1
 	blo	1b
 	dsb	st
 	ret	lr
 ENDPROC(v7m_flush_kern_dcache_area)

 /*
  *	v7m_dma_inv_range(start,end)
  *
  *	Invalidate the data cache within the specified region; we will
  *	be performing a DMA operation in this region and we want to
  *	purge old data in the cache.
  *
  *	- start   - virtual start address of region
  *	- end     - virtual end address of region
  */
 v7m_dma_inv_range:
 	dcache_line_size r2, r3
 	sub	r3, r2, #1
 	tst	r0, r3
 	bic	r0, r0, r3
 	dccimvacne r0, r3
 	addne	r0, r0, r2
 	subne	r3, r2, #1	@ restore r3, corrupted by v7m's dccimvac
 	tst	r1, r3
 	bic	r1, r1, r3
 	dccimvacne r1, r3
 	cmp	r0, r1
 1:
 	dcimvaclo r0, r3
 	addlo	r0, r0, r2
 	cmplo	r0, r1
 	blo	1b
 	dsb	st
 	ret	lr
 ENDPROC(v7m_dma_inv_range)

 /*
  *	v7m_dma_clean_range(start,end)
  *	- start   - virtual start address of region
  *	- end     - virtual end address of region
  */
 v7m_dma_clean_range:
 	dcache_line_size r2, r3
 	sub	r3, r2, #1
 	bic	r0, r0, r3
 1:
 	dccmvac r0, r3			@ clean D / U line
 	add	r0, r0, r2
 	cmp	r0, r1
 	blo	1b
 	dsb	st
 	ret	lr
 ENDPROC(v7m_dma_clean_range)

 /*
  *	v7m_dma_flush_range(start,end)
  *	- start   - virtual start address of region
  *	- end     - virtual end address of region
  */
 ENTRY(v7m_dma_flush_range)
 	dcache_line_size r2, r3
 	sub	r3, r2, #1
 	bic	r0, r0, r3
 1:
 	dccimvac r0, r3			 @ clean & invalidate D / U line
 	add	r0, r0, r2
 	cmp	r0, r1
 	blo	1b
 	dsb	st
 	ret	lr
 ENDPROC(v7m_dma_flush_range)

 /*
  *	dma_map_area(start, size, dir)
  *	- start	- kernel virtual start address
  *	- size	- size of region
  *	- dir	- DMA direction
  */
 ENTRY(v7m_dma_map_area)
 	add	r1, r1, r0
 	teq	r2, #DMA_FROM_DEVICE
 	beq	v7m_dma_inv_range
 	b	v7m_dma_clean_range
 ENDPROC(v7m_dma_map_area)

 /*
  *	dma_unmap_area(start, size, dir)
  *	- start	- kernel virtual start address
  *	- size	- size of region
  *	- dir	- DMA direction
  */
 ENTRY(v7m_dma_unmap_area)
 	add	r1, r1, r0
 	teq	r2, #DMA_TO_DEVICE
 	bne	v7m_dma_inv_range
 	ret	lr
 ENDPROC(v7m_dma_unmap_area)

 	.globl	v7m_flush_kern_cache_louis
 	.equ	v7m_flush_kern_cache_louis, v7m_flush_kern_cache_all

 	__INITDATA

 	@ define struct cpu_cache_fns (see <asm/cacheflush.h> and proc-macros.S)
 	define_cache_functions v7m
	/* SPDX-License-Identifier: GPL-2.0-only */
	/*
	* linux/arch/arm/mm/cache-v7m.S
	*
	* Based on linux/arch/arm/mm/cache-v7.S
	*
	* Copyright (C) 2001 Deep Blue Solutions Ltd.
	* Copyright (C) 2005 ARM Ltd.
	*
	* This is the "shell" of the ARMv7M processor support.
	*/
	#include <linux/linkage.h>
	#include <linux/init.h>
	#include <asm/assembler.h>
	#include <asm/errno.h>
	#include <asm/unwind.h>
	#include <asm/v7m.h>

	#include "proc-macros.S"

	/* Generic V7M read/write macros for memory mapped cache operations */
	.macro v7m_cache_read, rt, reg
	movw \rt, #:lower16:BASEADDR_V7M_SCB + \reg
	movt \rt, #:upper16:BASEADDR_V7M_SCB + \reg
	ldr \rt, [\rt]
	.endm

	.macro v7m_cacheop, rt, tmp, op, c = al
	movw\c \tmp, #:lower16:BASEADDR_V7M_SCB + \op
	movt\c \tmp, #:upper16:BASEADDR_V7M_SCB + \op
	str\c \rt, [\tmp]
	.endm


	.macro read_ccsidr, rt
	v7m_cache_read \rt, V7M_SCB_CCSIDR
	.endm

	.macro read_clidr, rt
	v7m_cache_read \rt, V7M_SCB_CLIDR
	.endm

	.macro write_csselr, rt, tmp
	v7m_cacheop \rt, \tmp, V7M_SCB_CSSELR
	.endm

	/*
	* dcisw: Invalidate data cache by set/way
	*/
	.macro dcisw, rt, tmp
	v7m_cacheop \rt, \tmp, V7M_SCB_DCISW
	.endm

	/*
	* dccisw: Clean and invalidate data cache by set/way
	*/
	.macro dccisw, rt, tmp
	v7m_cacheop \rt, \tmp, V7M_SCB_DCCISW
	.endm

	/*
	* dccimvac: Clean and invalidate data cache line by MVA to PoC.
	*/
	.irp c,,eq,ne,cs,cc,mi,pl,vs,vc,hi,ls,ge,lt,gt,le,hs,lo
	.macro dccimvac\c, rt, tmp
	v7m_cacheop \rt, \tmp, V7M_SCB_DCCIMVAC, \c
	.endm
	.endr

	/*
	* dcimvac: Invalidate data cache line by MVA to PoC
	*/
	.irp c,,eq,ne,cs,cc,mi,pl,vs,vc,hi,ls,ge,lt,gt,le,hs,lo
	.macro dcimvac\c, rt, tmp
	v7m_cacheop \rt, \tmp, V7M_SCB_DCIMVAC, \c
	.endm
	.endr

	/*
	* dccmvau: Clean data cache line by MVA to PoU
	*/
	.macro dccmvau, rt, tmp
	v7m_cacheop \rt, \tmp, V7M_SCB_DCCMVAU
	.endm

	/*
	* dccmvac: Clean data cache line by MVA to PoC
	*/
	.macro dccmvac, rt, tmp
	v7m_cacheop \rt, \tmp, V7M_SCB_DCCMVAC
	.endm

	/*
	* icimvau: Invalidate instruction caches by MVA to PoU
	*/
	.macro icimvau, rt, tmp
	v7m_cacheop \rt, \tmp, V7M_SCB_ICIMVAU
	.endm

	/*
	* Invalidate the icache, inner shareable if SMP, invalidate BTB for UP.
	* rt data ignored by ICIALLU(IS), so can be used for the address
	*/
	.macro invalidate_icache, rt
	v7m_cacheop \rt, \rt, V7M_SCB_ICIALLU
	mov \rt, #0
	.endm

	/*
	* Invalidate the BTB, inner shareable if SMP.
	* rt data ignored by BPIALL, so it can be used for the address
	*/
	.macro invalidate_bp, rt
	v7m_cacheop \rt, \rt, V7M_SCB_BPIALL
	mov \rt, #0
	.endm

	ENTRY(v7m_invalidate_l1)
	mov r0, #0

	write_csselr r0, r1
	read_ccsidr r0

	movw r1, #0x7fff
	and r2, r1, r0, lsr #13

	movw r1, #0x3ff

	and r3, r1, r0, lsr #3 @ NumWays - 1
	add r2, r2, #1 @ NumSets

	and r0, r0, #0x7
	add r0, r0, #4 @ SetShift

	clz r1, r3 @ WayShift
	add r4, r3, #1 @ NumWays
	1: sub r2, r2, #1 @ NumSets--
	mov r3, r4 @ Temp = NumWays
	2: subs r3, r3, #1 @ Temp--
	mov r5, r3, lsl r1
	mov r6, r2, lsl r0
	orr r5, r5, r6 @ Reg = (Temp<<WayShift)\|(NumSets<<SetShift)
	dcisw r5, r6
	bgt 2b
	cmp r2, #0
	bgt 1b
	dsb st
	isb
	ret lr
	ENDPROC(v7m_invalidate_l1)

	/*
	* v7m_flush_icache_all()
	*
	* Flush the whole I-cache.
	*
	* Registers:
	* r0 - set to 0
	*/
	ENTRY(v7m_flush_icache_all)
	invalidate_icache r0
	ret lr
	ENDPROC(v7m_flush_icache_all)

	/*
	* v7m_flush_dcache_all()
	*
	* Flush the whole D-cache.
	*
	* Corrupted registers: r0-r7, r9-r11
	*/
	ENTRY(v7m_flush_dcache_all)
	dmb @ ensure ordering with previous memory accesses
	read_clidr r0
	mov r3, r0, lsr #23 @ move LoC into position
	ands r3, r3, #7 << 1 @ extract LoC*2 from clidr
	beq finished @ if loc is 0, then no need to clean
	start_flush_levels:
	mov r10, #0 @ start clean at cache level 0
	flush_levels:
	add r2, r10, r10, lsr #1 @ work out 3x current cache level
	mov r1, r0, lsr r2 @ extract cache type bits from clidr
	and r1, r1, #7 @ mask of the bits for current cache only
	cmp r1, #2 @ see what cache we have at this level
	blt skip @ skip if no cache, or just i-cache
	#ifdef CONFIG_PREEMPT
	save_and_disable_irqs_notrace r9 @ make cssr&csidr read atomic
	#endif
	write_csselr r10, r1 @ set current cache level
	isb @ isb to sych the new cssr&csidr
	read_ccsidr r1 @ read the new csidr
	#ifdef CONFIG_PREEMPT
	restore_irqs_notrace r9
	#endif
	and r2, r1, #7 @ extract the length of the cache lines
	add r2, r2, #4 @ add 4 (line length offset)
	movw r4, #0x3ff
	ands r4, r4, r1, lsr #3 @ find maximum number on the way size
	clz r5, r4 @ find bit position of way size increment
	movw r7, #0x7fff
	ands r7, r7, r1, lsr #13 @ extract max number of the index size
	loop1:
	mov r9, r7 @ create working copy of max index
	loop2:
	lsl r6, r4, r5
	orr r11, r10, r6 @ factor way and cache number into r11
	lsl r6, r9, r2
	orr r11, r11, r6 @ factor index number into r11
	dccisw r11, r6 @ clean/invalidate by set/way
	subs r9, r9, #1 @ decrement the index
	bge loop2
	subs r4, r4, #1 @ decrement the way
	bge loop1
	skip:
	add r10, r10, #2 @ increment cache number
	cmp r3, r10
	bgt flush_levels
	finished:
	mov r10, #0 @ switch back to cache level 0
	write_csselr r10, r3 @ select current cache level in cssr
	dsb st
	isb
	ret lr
	ENDPROC(v7m_flush_dcache_all)

	/*
	* v7m_flush_cache_all()
	*
	* Flush the entire cache system.
	* The data cache flush is now achieved using atomic clean / invalidates
	* working outwards from L1 cache. This is done using Set/Way based cache
	* maintenance instructions.
	* The instruction cache can still be invalidated back to the point of
	* unification in a single instruction.
	*
	*/
	ENTRY(v7m_flush_kern_cache_all)
	stmfd sp!, {r4-r7, r9-r11, lr}
	bl v7m_flush_dcache_all
	invalidate_icache r0
	ldmfd sp!, {r4-r7, r9-r11, lr}
	ret lr
	ENDPROC(v7m_flush_kern_cache_all)

	/*
	* v7m_flush_cache_all()
	*
	* Flush all TLB entries in a particular address space
	*
	* - mm - mm_struct describing address space
	*/
	ENTRY(v7m_flush_user_cache_all)
	/FALLTHROUGH/

	/*
	* v7m_flush_cache_range(start, end, flags)
	*
	* Flush a range of TLB entries in the specified address space.
	*
	* - start - start address (may not be aligned)
	* - end - end address (exclusive, may not be aligned)
	* - flags - vm_area_struct flags describing address space
	*
	* It is assumed that:
	* - we have a VIPT cache.
	*/
	ENTRY(v7m_flush_user_cache_range)
	ret lr
	ENDPROC(v7m_flush_user_cache_all)
	ENDPROC(v7m_flush_user_cache_range)

	/*
	* v7m_coherent_kern_range(start,end)
	*
	* Ensure that the I and D caches are coherent within specified
	* region. This is typically used when code has been written to
	* a memory region, and will be executed.
	*
	* - start - virtual start address of region
	* - end - virtual end address of region
	*
	* It is assumed that:
	* - the Icache does not read data from the write buffer
	*/
	ENTRY(v7m_coherent_kern_range)
	/* FALLTHROUGH */

	/*
	* v7m_coherent_user_range(start,end)
	*
	* Ensure that the I and D caches are coherent within specified
	* region. This is typically used when code has been written to
	* a memory region, and will be executed.
	*
	* - start - virtual start address of region
	* - end - virtual end address of region
	*
	* It is assumed that:
	* - the Icache does not read data from the write buffer
	*/
	ENTRY(v7m_coherent_user_range)
	UNWIND(.fnstart )
	dcache_line_size r2, r3
	sub r3, r2, #1
	bic r12, r0, r3
	1:
	/*
	* We use open coded version of dccmvau otherwise USER() would
	* point at movw instruction.
	*/
	dccmvau r12, r3
	add r12, r12, r2
	cmp r12, r1
	blo 1b
	dsb ishst
	icache_line_size r2, r3
	sub r3, r2, #1
	bic r12, r0, r3
	2:
	icimvau r12, r3
	add r12, r12, r2
	cmp r12, r1
	blo 2b
	invalidate_bp r0
	dsb ishst
	isb
	ret lr
	UNWIND(.fnend )
	ENDPROC(v7m_coherent_kern_range)
	ENDPROC(v7m_coherent_user_range)

	/*
	* v7m_flush_kern_dcache_area(void *addr, size_t size)
	*
	* Ensure that the data held in the page kaddr is written back
	* to the page in question.
	*
	* - addr - kernel address
	* - size - region size
	*/
	ENTRY(v7m_flush_kern_dcache_area)
	dcache_line_size r2, r3
	add r1, r0, r1
	sub r3, r2, #1
	bic r0, r0, r3
	1:
	dccimvac r0, r3 @ clean & invalidate D line / unified line
	add r0, r0, r2
	cmp r0, r1
	blo 1b
	dsb st
	ret lr
	ENDPROC(v7m_flush_kern_dcache_area)

	/*
	* v7m_dma_inv_range(start,end)
	*
	* Invalidate the data cache within the specified region; we will
	* be performing a DMA operation in this region and we want to
	* purge old data in the cache.
	*
	* - start - virtual start address of region
	* - end - virtual end address of region
	*/
	v7m_dma_inv_range:
	dcache_line_size r2, r3
	sub r3, r2, #1
	tst r0, r3
	bic r0, r0, r3
	dccimvacne r0, r3
	addne r0, r0, r2
	subne r3, r2, #1 @ restore r3, corrupted by v7m's dccimvac
	tst r1, r3
	bic r1, r1, r3
	dccimvacne r1, r3
	cmp r0, r1
	1:
	dcimvaclo r0, r3
	addlo r0, r0, r2
	cmplo r0, r1
	blo 1b
	dsb st
	ret lr
	ENDPROC(v7m_dma_inv_range)

	/*
	* v7m_dma_clean_range(start,end)
	* - start - virtual start address of region
	* - end - virtual end address of region
	*/
	v7m_dma_clean_range:
	dcache_line_size r2, r3
	sub r3, r2, #1
	bic r0, r0, r3
	1:
	dccmvac r0, r3 @ clean D / U line
	add r0, r0, r2
	cmp r0, r1
	blo 1b
	dsb st
	ret lr
	ENDPROC(v7m_dma_clean_range)

	/*
	* v7m_dma_flush_range(start,end)
	* - start - virtual start address of region
	* - end - virtual end address of region
	*/
	ENTRY(v7m_dma_flush_range)
	dcache_line_size r2, r3
	sub r3, r2, #1
	bic r0, r0, r3
	1:
	dccimvac r0, r3 @ clean & invalidate D / U line
	add r0, r0, r2
	cmp r0, r1
	blo 1b
	dsb st
	ret lr
	ENDPROC(v7m_dma_flush_range)

	/*
	* dma_map_area(start, size, dir)
	* - start - kernel virtual start address
	* - size - size of region
	* - dir - DMA direction
	*/
	ENTRY(v7m_dma_map_area)
	add r1, r1, r0
	teq r2, #DMA_FROM_DEVICE
	beq v7m_dma_inv_range
	b v7m_dma_clean_range
	ENDPROC(v7m_dma_map_area)

	/*
	* dma_unmap_area(start, size, dir)
	* - start - kernel virtual start address
	* - size - size of region
	* - dir - DMA direction
	*/
	ENTRY(v7m_dma_unmap_area)
	add r1, r1, r0
	teq r2, #DMA_TO_DEVICE
	bne v7m_dma_inv_range
	ret lr
	ENDPROC(v7m_dma_unmap_area)

	.globl v7m_flush_kern_cache_louis
	.equ v7m_flush_kern_cache_louis, v7m_flush_kern_cache_all

	__INITDATA

	@ define struct cpu_cache_fns (see <asm/cacheflush.h> and proc-macros.S)
	define_cache_functions v7m