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 <[e-mail]>
Reviewed-by: Nicolas Pitre <[e-mail]>
Signed-off-by: Lorenzo Pieralisi <[e-mail]>
Tested-by: Shawn Guo <[e-mail]>

arch/arm/include/asm/cacheflush.h

···
  *
  *		Unconditionally clean and invalidate the entire cache.
  *
+ *     flush_kern_louis()
+ *
+ *             Flush data cache levels up to the level of unification
+ *             inner shareable and invalidate the I-cache.
+ *             Only needed from v7 onwards, falls back to flush_cache_all()
+ *             for all other processor versions.
+ *
  *	flush_user_all()
  *
  *		Clean and invalidate all user space cache entries
···
 struct cpu_cache_fns {
 	void (*flush_icache_all)(void);
 	void (*flush_kern_all)(void);
+	void (*flush_kern_louis)(void);
 	void (*flush_user_all)(void);
 	void (*flush_user_range)(unsigned long, unsigned long, unsigned int);
 
···
 
 #define __cpuc_flush_icache_all		cpu_cache.flush_icache_all
 #define __cpuc_flush_kern_all		cpu_cache.flush_kern_all
+#define __cpuc_flush_kern_louis		cpu_cache.flush_kern_louis
 #define __cpuc_flush_user_all		cpu_cache.flush_user_all
 #define __cpuc_flush_user_range		cpu_cache.flush_user_range
 #define __cpuc_coherent_kern_range	cpu_cache.coherent_kern_range
···
 
 extern void __cpuc_flush_icache_all(void);
 extern void __cpuc_flush_kern_all(void);
+extern void __cpuc_flush_kern_louis(void);
 extern void __cpuc_flush_user_all(void);
 extern void __cpuc_flush_user_range(unsigned long, unsigned long, unsigned int);
 extern void __cpuc_coherent_kern_range(unsigned long, unsigned long);
···
 {
 	__flush_icache_preferred();
 }
+
+/*
+ * Flush caches up to Level of Unification Inner Shareable
+ */
+#define flush_cache_louis()		__cpuc_flush_kern_louis()
 
 #define flush_cache_all()		__cpuc_flush_kern_all()
 

arch/arm/include/asm/glue-cache.h

···
 #ifndef MULTI_CACHE
 #define __cpuc_flush_icache_all		__glue(_CACHE,_flush_icache_all)
 #define __cpuc_flush_kern_all		__glue(_CACHE,_flush_kern_cache_all)
+#define __cpuc_flush_kern_louis		__glue(_CACHE,_flush_kern_cache_louis)
 #define __cpuc_flush_user_all		__glue(_CACHE,_flush_user_cache_all)
 #define __cpuc_flush_user_range		__glue(_CACHE,_flush_user_cache_range)
 #define __cpuc_coherent_kern_range	__glue(_CACHE,_coherent_kern_range)

arch/arm/mm/cache-fa.S

···
 	mov	pc, lr
 ENDPROC(fa_dma_unmap_area)
 
+	.globl	fa_flush_kern_cache_louis
+	.equ	fa_flush_kern_cache_louis, fa_flush_kern_cache_all
+
 	__INITDATA
 
 	@ define struct cpu_cache_fns (see <asm/cacheflush.h> and proc-macros.S)

arch/arm/mm/cache-v3.S

···
 ENDPROC(v3_dma_unmap_area)
 ENDPROC(v3_dma_map_area)
 
+	.globl	v3_flush_kern_cache_louis
+	.equ	v3_flush_kern_cache_louis, v3_flush_kern_cache_all
+
 	__INITDATA
 
 	@ define struct cpu_cache_fns (see <asm/cacheflush.h> and proc-macros.S)

arch/arm/mm/cache-v4.S

···
 ENDPROC(v4_dma_unmap_area)
 ENDPROC(v4_dma_map_area)
 
+	.globl	v4_flush_kern_cache_louis
+	.equ	v4_flush_kern_cache_louis, v4_flush_kern_cache_all
+
 	__INITDATA
 
 	@ define struct cpu_cache_fns (see <asm/cacheflush.h> and proc-macros.S)

arch/arm/mm/cache-v4wb.S

···
 	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)

arch/arm/mm/cache-v4wt.S

···
 ENDPROC(v4wt_dma_unmap_area)
 ENDPROC(v4wt_dma_map_area)
 
+	.globl	v4wt_flush_kern_cache_louis
+	.equ	v4wt_flush_kern_cache_louis, v4wt_flush_kern_cache_all
+
 	__INITDATA
 
 	@ define struct cpu_cache_fns (see <asm/cacheflush.h> and proc-macros.S)

arch/arm/mm/cache-v6.S

···
 	mov	pc, lr
 ENDPROC(v6_dma_unmap_area)
 
+	.globl	v6_flush_kern_cache_louis
+	.equ	v6_flush_kern_cache_louis, v6_flush_kern_cache_all
+
 	__INITDATA
 
 	@ define struct cpu_cache_fns (see <asm/cacheflush.h> and proc-macros.S)

arch/arm/mm/cache-v7.S

···
 	mov	pc, lr
 ENDPROC(v7_flush_icache_all)
 
+ /*
+ *     v7_flush_dcache_louis()
+ *
+ *     Flush the D-cache up to the Level of Unification Inner Shareable
+ *
+ *     Corrupted registers: r0-r7, r9-r11 (r6 only in Thumb mode)
+ */
+
+ENTRY(v7_flush_dcache_louis)
+	dmb					@ ensure ordering with previous memory accesses
+	mrc	p15, 1, r0, c0, c0, 1		@ read clidr, r0 = clidr
+	ands	r3, r0, #0xe00000		@ extract LoUIS from clidr
+	mov	r3, r3, lsr #20			@ r3 = LoUIS * 2
+	moveq	pc, lr				@ return if level == 0
+	mov	r10, #0				@ r10 (starting level) = 0
+	b	loop1				@ start flushing cache levels
+ENDPROC(v7_flush_dcache_louis)
+
 /*
  *	v7_flush_dcache_all()
  *
···
  THUMB(	ldmfd	sp!, {r4-r7, r9-r11, lr}	)
 	mov	pc, lr
 ENDPROC(v7_flush_kern_cache_all)
+
+ /*
+ *     v7_flush_kern_cache_louis(void)
+ *
+ *     Flush the data cache up to Level of Unification Inner Shareable.
+ *     Invalidate the I-cache to the point of unification.
+ */
+ENTRY(v7_flush_kern_cache_louis)
+ ARM(	stmfd	sp!, {r4-r5, r7, r9-r11, lr}	)
+ THUMB(	stmfd	sp!, {r4-r7, r9-r11, lr}	)
+	bl	v7_flush_dcache_louis
+	mov	r0, #0
+	ALT_SMP(mcr	p15, 0, r0, c7, c1, 0)	@ invalidate I-cache inner shareable
+	ALT_UP(mcr	p15, 0, r0, c7, c5, 0)	@ I+BTB cache invalidate
+ ARM(	ldmfd	sp!, {r4-r5, r7, r9-r11, lr}	)
+ THUMB(	ldmfd	sp!, {r4-r7, r9-r11, lr}	)
+	mov	pc, lr
+ENDPROC(v7_flush_kern_cache_louis)
 
 /*
  *	v7_flush_cache_all()

arch/arm/mm/proc-arm1020.S

···
 	mov	pc, lr
 ENDPROC(arm1020_dma_unmap_area)
 
+	.globl	arm1020_flush_kern_cache_louis
+	.equ	arm1020_flush_kern_cache_louis, arm1020_flush_kern_cache_all
+
 	@ define struct cpu_cache_fns (see <asm/cacheflush.h> and proc-macros.S)
 	define_cache_functions arm1020
 

arch/arm/mm/proc-arm1020e.S

···
 	mov	pc, lr
 ENDPROC(arm1020e_dma_unmap_area)
 
+	.globl	arm1020e_flush_kern_cache_louis
+	.equ	arm1020e_flush_kern_cache_louis, arm1020e_flush_kern_cache_all
+
 	@ define struct cpu_cache_fns (see <asm/cacheflush.h> and proc-macros.S)
 	define_cache_functions arm1020e
 

arch/arm/mm/proc-arm1022.S

···
 	mov	pc, lr
 ENDPROC(arm1022_dma_unmap_area)
 
+	.globl	arm1022_flush_kern_cache_louis
+	.equ	arm1022_flush_kern_cache_louis, arm1022_flush_kern_cache_all
+
 	@ define struct cpu_cache_fns (see <asm/cacheflush.h> and proc-macros.S)
 	define_cache_functions arm1022
 

arch/arm/mm/proc-arm1026.S

···
 	mov	pc, lr
 ENDPROC(arm1026_dma_unmap_area)
 
+	.globl	arm1026_flush_kern_cache_louis
+	.equ	arm1026_flush_kern_cache_louis, arm1026_flush_kern_cache_all
+
 	@ define struct cpu_cache_fns (see <asm/cacheflush.h> and proc-macros.S)
 	define_cache_functions arm1026
 

arch/arm/mm/proc-arm920.S

···
 	mov	pc, lr
 ENDPROC(arm920_dma_unmap_area)
 
+	.globl	arm920_flush_kern_cache_louis
+	.equ	arm920_flush_kern_cache_louis, arm920_flush_kern_cache_all
+
 	@ define struct cpu_cache_fns (see <asm/cacheflush.h> and proc-macros.S)
 	define_cache_functions arm920
 #endif

arch/arm/mm/proc-arm922.S

···
 	mov	pc, lr
 ENDPROC(arm922_dma_unmap_area)
 
+	.globl	arm922_flush_kern_cache_louis
+	.equ	arm922_flush_kern_cache_louis, arm922_flush_kern_cache_all
+
 	@ define struct cpu_cache_fns (see <asm/cacheflush.h> and proc-macros.S)
 	define_cache_functions arm922
 #endif

arch/arm/mm/proc-arm925.S

···
 	mov	pc, lr
 ENDPROC(arm925_dma_unmap_area)
 
+	.globl	arm925_flush_kern_cache_louis
+	.equ	arm925_flush_kern_cache_louis, arm925_flush_kern_cache_all
+
 	@ define struct cpu_cache_fns (see <asm/cacheflush.h> and proc-macros.S)
 	define_cache_functions arm925
 

arch/arm/mm/proc-arm926.S

···
 	mov	pc, lr
 ENDPROC(arm926_dma_unmap_area)
 
+	.globl	arm926_flush_kern_cache_louis
+	.equ	arm926_flush_kern_cache_louis, arm926_flush_kern_cache_all
+
 	@ define struct cpu_cache_fns (see <asm/cacheflush.h> and proc-macros.S)
 	define_cache_functions arm926
 

arch/arm/mm/proc-arm940.S

···
 	mov	pc, lr
 ENDPROC(arm940_dma_unmap_area)
 
+	.globl	arm940_flush_kern_cache_louis
+	.equ	arm940_flush_kern_cache_louis, arm940_flush_kern_cache_all
+
 	@ define struct cpu_cache_fns (see <asm/cacheflush.h> and proc-macros.S)
 	define_cache_functions arm940
 

arch/arm/mm/proc-arm946.S

···
 	mov	pc, lr
 ENDPROC(arm946_dma_unmap_area)
 
+	.globl	arm946_flush_kern_cache_louis
+	.equ	arm946_flush_kern_cache_louis, arm946_flush_kern_cache_all
+
 	@ define struct cpu_cache_fns (see <asm/cacheflush.h> and proc-macros.S)
 	define_cache_functions arm946
 

arch/arm/mm/proc-feroceon.S

···
 	mov	pc, lr
 ENDPROC(feroceon_dma_unmap_area)
 
+	.globl	feroceon_flush_kern_cache_louis
+	.equ	feroceon_flush_kern_cache_louis, feroceon_flush_kern_cache_all
+
 	@ define struct cpu_cache_fns (see <asm/cacheflush.h> and proc-macros.S)
 	define_cache_functions feroceon
 

arch/arm/mm/proc-macros.S

···
 ENTRY(\name\()_cache_fns)
 	.long	\name\()_flush_icache_all
 	.long	\name\()_flush_kern_cache_all
+	.long   \name\()_flush_kern_cache_louis
 	.long	\name\()_flush_user_cache_all
 	.long	\name\()_flush_user_cache_range
 	.long	\name\()_coherent_kern_range

arch/arm/mm/proc-mohawk.S

···
 	mov	pc, lr
 ENDPROC(mohawk_dma_unmap_area)
 
+	.globl	mohawk_flush_kern_cache_louis
+	.equ	mohawk_flush_kern_cache_louis, mohawk_flush_kern_cache_all
+
 	@ define struct cpu_cache_fns (see <asm/cacheflush.h> and proc-macros.S)
 	define_cache_functions mohawk
 

arch/arm/mm/proc-xsc3.S

···
 	mov	pc, lr
 ENDPROC(xsc3_dma_unmap_area)
 
+	.globl	xsc3_flush_kern_cache_louis
+	.equ	xsc3_flush_kern_cache_louis, xsc3_flush_kern_cache_all
+
 	@ define struct cpu_cache_fns (see <asm/cacheflush.h> and proc-macros.S)
 	define_cache_functions xsc3
 

arch/arm/mm/proc-xscale.S

···
 	mov	pc, lr
 ENDPROC(xscale_dma_unmap_area)
 
+	.globl	xscale_flush_kern_cache_louis
+	.equ	xscale_flush_kern_cache_louis, xscale_flush_kern_cache_all
+
 	@ define struct cpu_cache_fns (see <asm/cacheflush.h> and proc-macros.S)
 	define_cache_functions xscale