arch/arm/cache-ops.S - kernel/lk - Gitiles

 /*
  * Copyright (c) 2008 Travis Geiselbrecht
  *
  * Permission is hereby granted, free of charge, to any person obtaining
  * a copy of this software and associated documentation files
  * (the "Software"), to deal in the Software without restriction,
  * including without limitation the rights to use, copy, modify, merge,
  * publish, distribute, sublicense, and/or sell copies of the Software,
  * and to permit persons to whom the Software is furnished to do so,
  * subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be
  * included in all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
  * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
 #include <asm.h>
 #include <arch/ops.h>
 #include <arch/defines.h>

 .text

 #if ARM_WITH_CACHE

 /* low level cache routines for various cpu families */

 #if ARM_CPU_ARM1136 || ARM_CPU_ARM926

 /* void arch_disable_cache(uint flags) */
 FUNCTION(arch_disable_cache)
 	mov		r12, #0						// zero register
 	mrs		r3, cpsr					// save the old interrupt state
 #if ARM_ISA_ARMv6
 	.word	0xf10c01c0	/* cpsid iaf */	// interrupts disabled
 #else
 	orr		r3, r3, #(1<<7)
 	msr		cpsr, r3
 #endif

 .Ldcache_disable:
 	tst		r0, #DCACHE
 	beq		.Licache_disable
 	mrc     p15, 0, r1, c1, c0, 0		// cr1
 	tst		r1, #(1<<2)					// is the dcache already disabled?
 	beq		.Licache_disable

 	bic		r1, #(1<<2)
 	mcr		p15, 0, r1, c1, c0, 0		// disable dcache

 #if ARM_CPU_ARM1136
     mcr     p15, 0, r12, c7, c14, 0     // clean & invalidate dcache
 #elif ARM_CPU_ARM926
 0:
 	mrc		p15, 0, r15, c7, c14, 3		// clean & invalidate dcache
 	bne		0b
 #else
 #error whut?
 #endif
 	mcr		p15, 0, r0, c7, c10, 4		// data sync barrier (formerly drain write buffer)

 .Licache_disable:
 	tst		r0, #ICACHE
 	beq		.Ldone_disable

 	mrc     p15, 0, r1, c1, c0, 0		// cr1
 	bic		r1, #(1<<12)
 	mcr		p15, 0, r1, c1, c0, 0		// disable icache

 	mcr		p15, 0, r12, c7, c5, 0		// invalidate icache

 .Ldone_disable:
 	msr		cpsr, r3
 	bx		lr

 /* void arch_enable_cache(uint flags) */
 FUNCTION(arch_enable_cache)
 	mov		r12, #0						// zero register
 	mrs		r3, cpsr					// save the old interrupt state
 #if ARM_ISA_ARMv6
 	.word	0xf10c01c0	/* cpsid iaf */	// interrupts disabled
 #else
 	orr		r3, r3, #(1<<7)
 	msr		cpsr, r3
 #endif

 .Ldcache_enable:
 	tst		r0, #DCACHE
 	beq		.Licache_enable
 	mrc     p15, 0, r1, c1, c0, 0		// cr1
 	tst		r1, #(1<<2)					// is the dcache already enabled?
 	bne		.Licache_enable

     mcr     p15, 0, r12, c7, c6, 0      // invalidate dcache

 	orr		r1, #(1<<2)
 	mcr		p15, 0, r1, c1, c0, 0		// enable dcache

 .Licache_enable:
 	tst		r0, #ICACHE
 	beq		.Ldone_enable

 	mcr		p15, 0, r12, c7, c5, 0		// invalidate icache

 	mrc     p15, 0, r1, c1, c0, 0		// cr1
 	orr		r1, #(1<<12)
 	mcr		p15, 0, r1, c1, c0, 0		// enable icache

 .Ldone_enable:
 	msr		cpsr, r3
 	bx		lr

 #elif ARM_CPU_CORTEX_A8

 /* void arch_disable_cache(uint flags) */
 FUNCTION(arch_disable_cache)
 	stmfd	sp!, {r4-r11, lr}

 	mov		r7, r0						// save flags

 	mrs		r12, cpsr					// save the old interrupt state
 	.word	0xf10c01c0	/* cpsid iaf */	// interrupts disabled

 .Ldcache_disable:
 	tst		r7, #DCACHE
 	beq		.Licache_disable
 	mrc     p15, 0, r0, c1, c0, 0		// cr1
 	tst		r0, #(1<<2)					// is the dcache already disabled?
 	beq		.Ldcache_already_disabled

 	bic		r0, #(1<<2)
 	mcr		p15, 0, r0, c1, c0, 0		// disable dcache

 	// flush and invalidate the dcache
 	// NOTE: trashes a bunch of registers, can't be spilling stuff to the stack
 	bl		flush_invalidate_cache_v7

 	b		.Ldcache_disable_L2

 .Ldcache_already_disabled:
 	// make sure all of the caches are invalidated
 	// NOTE: trashes a bunch of registers, can't be spilling stuff to the stack
 	bl		invalidate_cache_v7

 .Ldcache_disable_L2:

 #if ARM_WITH_L2
 	// disable the L2, if present
 	mrc     p15, 0, r0, c1, c0, 1		// aux cr1
 	bic		r0, #(1<<1)
 	mcr		p15, 0, r0, c1, c0, 1		// disable L2 dcache
 #endif

 .Licache_disable:
 	tst		r7, #ICACHE
 	beq		.Ldone_disable

 	mrc     p15, 0, r0, c1, c0, 0		// cr1
 	bic		r0, #(1<<12)
 	mcr		p15, 0, r0, c1, c0, 0		// disable icache

 .Ldone_disable:
 	// make sure the icache is always invalidated
 	mov		r0, #0
 	mcr		p15, 0, r0, c7, c5, 0		// invalidate icache to PoU

 	msr		cpsr, r12
 	ldmfd	sp!, {r4-r11, pc}

 /* void arch_enable_cache(uint flags) */
 FUNCTION(arch_enable_cache)
 	stmfd	sp!, {r4-r11, lr}

 	mov		r7, r0						// save flags

 	mrs		r12, cpsr					// save the old interrupt state
 	.word	0xf10c01c0	/* cpsid iaf */	// interrupts disabled

 .Ldcache_enable:
 	tst		r7, #DCACHE
 	beq		.Licache_enable
 	mrc     p15, 0, r0, c1, c0, 0		// cr1
 	tst		r0, #(1<<2)					// is the dcache already enabled?
 	bne		.Licache_enable

 	// invalidate L1 and L2
 	// NOTE: trashes a bunch of registers, can't be spilling stuff to the stack
 	bl		invalidate_cache_v7

 #if ARM_WITH_L2
 	// enable the L2, if present
 	mrc     p15, 0, r0, c1, c0, 1		// aux cr1
 	orr		r0, #(1<<1)
 	mcr		p15, 0, r0, c1, c0, 1		// enable L2 dcache
 #endif

 	mrc     p15, 0, r0, c1, c0, 0		// cr1
 	orr		r0, #(1<<2)
 	mcr		p15, 0, r0, c1, c0, 0		// enable dcache

 .Licache_enable:
 	tst		r7, #ICACHE
 	beq		.Ldone_enable

 	mov		r0, #0
 	mcr		p15, 0, r0, c7, c5, 0		// invalidate icache to PoU

 	mrc     p15, 0, r0, c1, c0, 0		// cr1
 	orr		r0, #(1<<12)
 	mcr		p15, 0, r0, c1, c0, 0		// enable icache

 .Ldone_enable:
 	msr		cpsr, r12
 	ldmfd	sp!, {r4-r11, pc}

 // flush & invalidate cache routine, trashes r0-r6, r9-r11
 flush_invalidate_cache_v7:
 	/* from ARMv7 manual, B2-17 */
 	MRC 	p15, 1, R0, c0, c0, 1 		// Read CLIDR
 	ANDS 	R3, R0, #0x7000000
 	MOV 	R3, R3, LSR #23 			// Cache level value (naturally aligned)
 	BEQ 	.Lfinished
 	MOV 	R10, #0
 .Loop1:
 	ADD 	R2, R10, R10, LSR #1 		// Work out 3xcachelevel
 	MOV 	R1, R0, LSR R2 				// bottom 3 bits are the Cache type for this level
 	AND 	R1, R1, #7 					// get those 3 bits alone
 	CMP 	R1, #2
 	BLT 	.Lskip 						// no cache or only instruction cache at this level
 	MCR 	p15, 2, R10, c0, c0, 0 		// write the Cache Size selection register
 	.word	0xf57ff06f	// ISB 			// ISB to sync the change to the CacheSizeID reg
 	MRC 	p15, 1, R1, c0, c0, 0 		// reads current Cache Size ID register
 	AND 	R2, R1, #0x7 				// extract the line length field
 	ADD 	R2, R2, #4 					// add 4 for the line length offset (log2 16 bytes)
 	LDR 	R4, =0x3FF
 	ANDS 	R4, R4, R1, LSR #3 			// R4 is the max number on the way size (right aligned)
 	CLZ 	R5, R4 						// R5 is the bit position of the way size increment
 	LDR 	R6, =0x00007FFF
 	ANDS 	R6, R6, R1, LSR #13 		// R6 is the max number of the index size (right aligned)
 .Loop2:
 	MOV 	R9, R4 						// R9 working copy of the max way size (right aligned)
 .Loop3:
 	ORR 	R11, R10, R9, LSL R5 		// factor in the way number and cache number into R11
 	ORR 	R11, R11, R6, LSL R2 		// factor in the index number
 	MCR 	p15, 0, R11, c7, c14, 2 	// clean & invalidate by set/way
 	SUBS 	R9, R9, #1 					// decrement the way number
 	BGE 	.Loop3
 	SUBS 	R6, R6, #1 					// decrement the index
 	BGE 	.Loop2
 .Lskip:
  	ADD 	R10, R10, #2 					// increment the cache number
 	CMP 	R3, R10
 	BGT 	.Loop1

 .Lfinished:
 	mov		r10, #0
 	mcr		p15, 2, r10, c0, c0, 0		// select cache level 0
 	.word	0xf57ff06f	// isb

 	bx		lr

 // invalidate cache routine, trashes r0-r6, r9-r11
 invalidate_cache_v7:
 	/* from ARMv7 manual, B2-17 */
 	MRC 	p15, 1, R0, c0, c0, 1 		// Read CLIDR
 	ANDS 	R3, R0, #0x7000000
 	MOV 	R3, R3, LSR #23 			// Cache level value (naturally aligned)
 	BEQ 	.Lfinished_invalidate
 	MOV 	R10, #0
 .Loop1_invalidate:
 	ADD 	R2, R10, R10, LSR #1 		// Work out 3xcachelevel
 	MOV 	R1, R0, LSR R2 				// bottom 3 bits are the Cache type for this level
 	AND 	R1, R1, #7 					// get those 3 bits alone
 	CMP 	R1, #2
 	BLT 	.Lskip_invalidate 			// no cache or only instruction cache at this level
 	MCR 	p15, 2, R10, c0, c0, 0 		// write the Cache Size selection register
 	.word	0xf57ff06f	// ISB 			// ISB to sync the change to the CacheSizeID reg
 	MRC 	p15, 1, R1, c0, c0, 0 		// reads current Cache Size ID register
 	AND 	R2, R1, #0x7 				// extract the line length field
 	ADD 	R2, R2, #4 					// add 4 for the line length offset (log2 16 bytes)
 	LDR 	R4, =0x3FF
 	ANDS 	R4, R4, R1, LSR #3 			// R4 is the max number on the way size (right aligned)
 	CLZ 	R5, R4 						// R5 is the bit position of the way size increment
 	LDR 	R6, =0x00007FFF
 	ANDS 	R6, R6, R1, LSR #13 		// R6 is the max number of the index size (right aligned)
 .Loop2_invalidate:
 	MOV 	R9, R4 						// R9 working copy of the max way size (right aligned)
 .Loop3_invalidate:
 	ORR 	R11, R10, R9, LSL R5 		// factor in the way number and cache number into R11
 	ORR 	R11, R11, R6, LSL R2 		// factor in the index number
 	MCR 	p15, 0, R11, c7, c6, 2 		// invalidate by set/way
 	SUBS 	R9, R9, #1 					// decrement the way number
 	BGE 	.Loop3_invalidate
 	SUBS 	R6, R6, #1 					// decrement the index
 	BGE 	.Loop2_invalidate
 .Lskip_invalidate:
  	ADD 	R10, R10, #2 				// increment the cache number
 	CMP 	R3, R10
 	BGT 	.Loop1_invalidate

 .Lfinished_invalidate:
 	mov		r10, #0
 	mcr		p15, 2, r10, c0, c0, 0		// select cache level 0
 	.word	0xf57ff06f	// isb

 	bx		lr

 #else
 #error unhandled cpu
 #endif

 #if ARM_CPU_ARM926 || ARM_CPU_ARM1136 || ARM_CPU_CORTEX_A8
 /* shared cache flush routines */

 	/* void arch_flush_cache_range(addr_t start, size_t len); */
 FUNCTION(arch_clean_cache_range)
 0:
 	mcr		p15, 0, r0, c7, c10, 1		// clean cache to PoC by MVA
 	add		r0, r0, #CACHE_LINE
 	subs	r1, r1, #CACHE_LINE
 	bhs		0b

 	mov		r0, #0
 	mcr		p15, 0, r0, c7, c10, 4		// data sync barrier (formerly drain write buffer)

 	bx		lr

 	/* void arch_flush_invalidate_cache_range(addr_t start, size_t len); */
 FUNCTION(arch_clean_invalidate_cache_range)
 0:
 	mcr		p15, 0, r0, c7, c14, 1		// clean & invalidate cache to PoC by MVA
 	add		r0, r0, #CACHE_LINE
 	subs	r1, r1, #CACHE_LINE
 	bhs		0b

 	mov		r0, #0
 	mcr		p15, 0, r0, c7, c10, 4		// data sync barrier (formerly drain write buffer)

 	bx		lr
 #else
 #error unhandled cpu
 #endif

 #else

 /* no cache */

 FUNCTION(arch_disable_cache)
 	bx		lr

 FUNCTION(arch_enable_cache)
 	bx		lr

 FUNCTION(arch_clean_cache_range)
 	bx		lr

 FUNCTION(arch_clean_invalidate_cache_range)
 	bx		lr

 #endif // ARM_WITH_CACHE
	/*
	* Copyright (c) 2008 Travis Geiselbrecht
	*
	* Permission is hereby granted, free of charge, to any person obtaining
	* a copy of this software and associated documentation files
	* (the "Software"), to deal in the Software without restriction,
	* including without limitation the rights to use, copy, modify, merge,
	* publish, distribute, sublicense, and/or sell copies of the Software,
	* and to permit persons to whom the Software is furnished to do so,
	* subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be
	* included in all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
	* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
	* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
	* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
	* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
	* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
	* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
	*/
	#include <asm.h>
	#include <arch/ops.h>
	#include <arch/defines.h>

	.text

	#if ARM_WITH_CACHE

	/* low level cache routines for various cpu families */

	#if ARM_CPU_ARM1136 \|\| ARM_CPU_ARM926

	/* void arch_disable_cache(uint flags) */
	FUNCTION(arch_disable_cache)
	mov r12, #0 // zero register
	mrs r3, cpsr // save the old interrupt state
	#if ARM_ISA_ARMv6
	.word 0xf10c01c0 /* cpsid iaf */ // interrupts disabled
	#else
	orr r3, r3, #(1<<7)
	msr cpsr, r3
	#endif

	.Ldcache_disable:
	tst r0, #DCACHE
	beq .Licache_disable
	mrc p15, 0, r1, c1, c0, 0 // cr1
	tst r1, #(1<<2) // is the dcache already disabled?
	beq .Licache_disable

	bic r1, #(1<<2)
	mcr p15, 0, r1, c1, c0, 0 // disable dcache

	#if ARM_CPU_ARM1136
	mcr p15, 0, r12, c7, c14, 0 // clean & invalidate dcache
	#elif ARM_CPU_ARM926
	0:
	mrc p15, 0, r15, c7, c14, 3 // clean & invalidate dcache
	bne 0b
	#else
	#error whut?
	#endif
	mcr p15, 0, r0, c7, c10, 4 // data sync barrier (formerly drain write buffer)

	.Licache_disable:
	tst r0, #ICACHE
	beq .Ldone_disable

	mrc p15, 0, r1, c1, c0, 0 // cr1
	bic r1, #(1<<12)
	mcr p15, 0, r1, c1, c0, 0 // disable icache

	mcr p15, 0, r12, c7, c5, 0 // invalidate icache

	.Ldone_disable:
	msr cpsr, r3
	bx lr

	/* void arch_enable_cache(uint flags) */
	FUNCTION(arch_enable_cache)
	mov r12, #0 // zero register
	mrs r3, cpsr // save the old interrupt state
	#if ARM_ISA_ARMv6
	.word 0xf10c01c0 /* cpsid iaf */ // interrupts disabled
	#else
	orr r3, r3, #(1<<7)
	msr cpsr, r3
	#endif

	.Ldcache_enable:
	tst r0, #DCACHE
	beq .Licache_enable
	mrc p15, 0, r1, c1, c0, 0 // cr1
	tst r1, #(1<<2) // is the dcache already enabled?
	bne .Licache_enable

	mcr p15, 0, r12, c7, c6, 0 // invalidate dcache

	orr r1, #(1<<2)
	mcr p15, 0, r1, c1, c0, 0 // enable dcache

	.Licache_enable:
	tst r0, #ICACHE
	beq .Ldone_enable

	mcr p15, 0, r12, c7, c5, 0 // invalidate icache

	mrc p15, 0, r1, c1, c0, 0 // cr1
	orr r1, #(1<<12)
	mcr p15, 0, r1, c1, c0, 0 // enable icache

	.Ldone_enable:
	msr cpsr, r3
	bx lr

	#elif ARM_CPU_CORTEX_A8

	/* void arch_disable_cache(uint flags) */
	FUNCTION(arch_disable_cache)
	stmfd sp!, {r4-r11, lr}

	mov r7, r0 // save flags

	mrs r12, cpsr // save the old interrupt state
	.word 0xf10c01c0 /* cpsid iaf */ // interrupts disabled

	.Ldcache_disable:
	tst r7, #DCACHE
	beq .Licache_disable
	mrc p15, 0, r0, c1, c0, 0 // cr1
	tst r0, #(1<<2) // is the dcache already disabled?
	beq .Ldcache_already_disabled

	bic r0, #(1<<2)
	mcr p15, 0, r0, c1, c0, 0 // disable dcache

	// flush and invalidate the dcache
	// NOTE: trashes a bunch of registers, can't be spilling stuff to the stack
	bl flush_invalidate_cache_v7

	b .Ldcache_disable_L2

	.Ldcache_already_disabled:
	// make sure all of the caches are invalidated
	// NOTE: trashes a bunch of registers, can't be spilling stuff to the stack
	bl invalidate_cache_v7

	.Ldcache_disable_L2:

	#if ARM_WITH_L2
	// disable the L2, if present
	mrc p15, 0, r0, c1, c0, 1 // aux cr1
	bic r0, #(1<<1)
	mcr p15, 0, r0, c1, c0, 1 // disable L2 dcache
	#endif

	.Licache_disable:
	tst r7, #ICACHE
	beq .Ldone_disable

	mrc p15, 0, r0, c1, c0, 0 // cr1
	bic r0, #(1<<12)
	mcr p15, 0, r0, c1, c0, 0 // disable icache

	.Ldone_disable:
	// make sure the icache is always invalidated
	mov r0, #0
	mcr p15, 0, r0, c7, c5, 0 // invalidate icache to PoU

	msr cpsr, r12
	ldmfd sp!, {r4-r11, pc}

	/* void arch_enable_cache(uint flags) */
	FUNCTION(arch_enable_cache)
	stmfd sp!, {r4-r11, lr}

	mov r7, r0 // save flags

	mrs r12, cpsr // save the old interrupt state
	.word 0xf10c01c0 /* cpsid iaf */ // interrupts disabled

	.Ldcache_enable:
	tst r7, #DCACHE
	beq .Licache_enable
	mrc p15, 0, r0, c1, c0, 0 // cr1
	tst r0, #(1<<2) // is the dcache already enabled?
	bne .Licache_enable

	// invalidate L1 and L2
	// NOTE: trashes a bunch of registers, can't be spilling stuff to the stack
	bl invalidate_cache_v7

	#if ARM_WITH_L2
	// enable the L2, if present
	mrc p15, 0, r0, c1, c0, 1 // aux cr1
	orr r0, #(1<<1)
	mcr p15, 0, r0, c1, c0, 1 // enable L2 dcache
	#endif

	mrc p15, 0, r0, c1, c0, 0 // cr1
	orr r0, #(1<<2)
	mcr p15, 0, r0, c1, c0, 0 // enable dcache

	.Licache_enable:
	tst r7, #ICACHE
	beq .Ldone_enable

	mov r0, #0
	mcr p15, 0, r0, c7, c5, 0 // invalidate icache to PoU

	mrc p15, 0, r0, c1, c0, 0 // cr1
	orr r0, #(1<<12)
	mcr p15, 0, r0, c1, c0, 0 // enable icache

	.Ldone_enable:
	msr cpsr, r12
	ldmfd sp!, {r4-r11, pc}

	// flush & invalidate cache routine, trashes r0-r6, r9-r11
	flush_invalidate_cache_v7:
	/* from ARMv7 manual, B2-17 */
	MRC p15, 1, R0, c0, c0, 1 // Read CLIDR
	ANDS R3, R0, #0x7000000
	MOV R3, R3, LSR #23 // Cache level value (naturally aligned)
	BEQ .Lfinished
	MOV R10, #0
	.Loop1:
	ADD R2, R10, R10, LSR #1 // Work out 3xcachelevel
	MOV R1, R0, LSR R2 // bottom 3 bits are the Cache type for this level
	AND R1, R1, #7 // get those 3 bits alone
	CMP R1, #2
	BLT .Lskip // no cache or only instruction cache at this level
	MCR p15, 2, R10, c0, c0, 0 // write the Cache Size selection register
	.word 0xf57ff06f // ISB // ISB to sync the change to the CacheSizeID reg
	MRC p15, 1, R1, c0, c0, 0 // reads current Cache Size ID register
	AND R2, R1, #0x7 // extract the line length field
	ADD R2, R2, #4 // add 4 for the line length offset (log2 16 bytes)
	LDR R4, =0x3FF
	ANDS R4, R4, R1, LSR #3 // R4 is the max number on the way size (right aligned)
	CLZ R5, R4 // R5 is the bit position of the way size increment
	LDR R6, =0x00007FFF
	ANDS R6, R6, R1, LSR #13 // R6 is the max number of the index size (right aligned)
	.Loop2:
	MOV R9, R4 // R9 working copy of the max way size (right aligned)
	.Loop3:
	ORR R11, R10, R9, LSL R5 // factor in the way number and cache number into R11
	ORR R11, R11, R6, LSL R2 // factor in the index number
	MCR p15, 0, R11, c7, c14, 2 // clean & invalidate by set/way
	SUBS R9, R9, #1 // decrement the way number
	BGE .Loop3
	SUBS R6, R6, #1 // decrement the index
	BGE .Loop2
	.Lskip:
	ADD R10, R10, #2 // increment the cache number
	CMP R3, R10
	BGT .Loop1

	.Lfinished:
	mov r10, #0
	mcr p15, 2, r10, c0, c0, 0 // select cache level 0
	.word 0xf57ff06f // isb

	bx lr

	// invalidate cache routine, trashes r0-r6, r9-r11
	invalidate_cache_v7:
	/* from ARMv7 manual, B2-17 */
	MRC p15, 1, R0, c0, c0, 1 // Read CLIDR
	ANDS R3, R0, #0x7000000
	MOV R3, R3, LSR #23 // Cache level value (naturally aligned)
	BEQ .Lfinished_invalidate
	MOV R10, #0
	.Loop1_invalidate:
	ADD R2, R10, R10, LSR #1 // Work out 3xcachelevel
	MOV R1, R0, LSR R2 // bottom 3 bits are the Cache type for this level
	AND R1, R1, #7 // get those 3 bits alone
	CMP R1, #2
	BLT .Lskip_invalidate // no cache or only instruction cache at this level
	MCR p15, 2, R10, c0, c0, 0 // write the Cache Size selection register
	.word 0xf57ff06f // ISB // ISB to sync the change to the CacheSizeID reg
	MRC p15, 1, R1, c0, c0, 0 // reads current Cache Size ID register
	AND R2, R1, #0x7 // extract the line length field
	ADD R2, R2, #4 // add 4 for the line length offset (log2 16 bytes)
	LDR R4, =0x3FF
	ANDS R4, R4, R1, LSR #3 // R4 is the max number on the way size (right aligned)
	CLZ R5, R4 // R5 is the bit position of the way size increment
	LDR R6, =0x00007FFF
	ANDS R6, R6, R1, LSR #13 // R6 is the max number of the index size (right aligned)
	.Loop2_invalidate:
	MOV R9, R4 // R9 working copy of the max way size (right aligned)
	.Loop3_invalidate:
	ORR R11, R10, R9, LSL R5 // factor in the way number and cache number into R11
	ORR R11, R11, R6, LSL R2 // factor in the index number
	MCR p15, 0, R11, c7, c6, 2 // invalidate by set/way
	SUBS R9, R9, #1 // decrement the way number
	BGE .Loop3_invalidate
	SUBS R6, R6, #1 // decrement the index
	BGE .Loop2_invalidate
	.Lskip_invalidate:
	ADD R10, R10, #2 // increment the cache number
	CMP R3, R10
	BGT .Loop1_invalidate

	.Lfinished_invalidate:
	mov r10, #0
	mcr p15, 2, r10, c0, c0, 0 // select cache level 0
	.word 0xf57ff06f // isb

	bx lr

	#else
	#error unhandled cpu
	#endif

	#if ARM_CPU_ARM926 \|\| ARM_CPU_ARM1136 \|\| ARM_CPU_CORTEX_A8
	/* shared cache flush routines */

	/* void arch_flush_cache_range(addr_t start, size_t len); */
	FUNCTION(arch_clean_cache_range)
	0:
	mcr p15, 0, r0, c7, c10, 1 // clean cache to PoC by MVA
	add r0, r0, #CACHE_LINE
	subs r1, r1, #CACHE_LINE
	bhs 0b

	mov r0, #0
	mcr p15, 0, r0, c7, c10, 4 // data sync barrier (formerly drain write buffer)

	bx lr

	/* void arch_flush_invalidate_cache_range(addr_t start, size_t len); */
	FUNCTION(arch_clean_invalidate_cache_range)
	0:
	mcr p15, 0, r0, c7, c14, 1 // clean & invalidate cache to PoC by MVA
	add r0, r0, #CACHE_LINE
	subs r1, r1, #CACHE_LINE
	bhs 0b

	mov r0, #0
	mcr p15, 0, r0, c7, c10, 4 // data sync barrier (formerly drain write buffer)

	bx lr
	#else
	#error unhandled cpu
	#endif

	#else

	/* no cache */

	FUNCTION(arch_disable_cache)
	bx lr

	FUNCTION(arch_enable_cache)
	bx lr

	FUNCTION(arch_clean_cache_range)
	bx lr

	FUNCTION(arch_clean_invalidate_cache_range)
	bx lr

	#endif // ARM_WITH_CACHE