[PATCH V9 03/13] MIPS: Loongson: Introduce and use cpu_has_coherent_cache feature

[Huacai Chen <chenhc@xxxxxxxxxx>]

Loongson-3 maintains cache coherency by hardware. So we introduce a cpu
feature named cpu_has_coherent_cache and use it to modify MIPS's cache
flushing functions.

Signed-off-by: Huacai Chen <chenhc@xxxxxxxxxx>
Signed-off-by: Hongliang Tao <taohl@xxxxxxxxxx>
Signed-off-by: Hua Yan <yanh@xxxxxxxxxx>
---
 arch/mips/include/asm/cacheflush.h                 |    6 +++++
 arch/mips/include/asm/cpu-features.h               |    3 ++
 .../asm/mach-loongson/cpu-feature-overrides.h      |    6 +++++
 arch/mips/mm/c-r4k.c                               |   21 ++++++++++++++++++-
 4 files changed, 34 insertions(+), 2 deletions(-)

diff --git a/arch/mips/include/asm/cacheflush.h b/arch/mips/include/asm/cacheflush.h
index 69468de..8c4fa0d 100644
--- a/arch/mips/include/asm/cacheflush.h
+++ b/arch/mips/include/asm/cacheflush.h
@@ -70,6 +70,9 @@ extern void (*__flush_cache_vmap)(void);
 
 static inline void flush_cache_vmap(unsigned long start, unsigned long end)
 {
+	if (cpu_has_coherent_cache)
+		return;
+
 	if (cpu_has_dc_aliases)
 		__flush_cache_vmap();
 }
@@ -78,6 +81,9 @@ extern void (*__flush_cache_vunmap)(void);
 
 static inline void flush_cache_vunmap(unsigned long start, unsigned long end)
 {
+	if (cpu_has_coherent_cache)
+		return;
+
 	if (cpu_has_dc_aliases)
 		__flush_cache_vunmap();
 }
diff --git a/arch/mips/include/asm/cpu-features.h b/arch/mips/include/asm/cpu-features.h
index c507b93..55213ca 100644
--- a/arch/mips/include/asm/cpu-features.h
+++ b/arch/mips/include/asm/cpu-features.h
@@ -110,6 +110,9 @@
 #ifndef cpu_has_pindexed_dcache
 #define cpu_has_pindexed_dcache	(cpu_data[0].dcache.flags & MIPS_CACHE_PINDEX)
 #endif
+#ifndef cpu_has_coherent_cache
+#define cpu_has_coherent_cache	0
+#endif
 
 /*
  * I-Cache snoops remote store.  This only matters on SMP.  Some multiprocessors
diff --git a/arch/mips/include/asm/mach-loongson/cpu-feature-overrides.h b/arch/mips/include/asm/mach-loongson/cpu-feature-overrides.h
index 1a05d85..f72b6be 100644
--- a/arch/mips/include/asm/mach-loongson/cpu-feature-overrides.h
+++ b/arch/mips/include/asm/mach-loongson/cpu-feature-overrides.h
@@ -57,5 +57,11 @@
 #define cpu_has_vint		0
 #define cpu_has_vtag_icache	0
 #define cpu_has_watch		1
+#ifdef CONFIG_CPU_SUPPORTS_COHERENT_CACHE
+#define cpu_has_coherent_cache	1
+#else
+#define cpu_has_coherent_cache	0
+#endif
+
 
 #endif /* __ASM_MACH_LOONGSON_CPU_FEATURE_OVERRIDES_H */
diff --git a/arch/mips/mm/c-r4k.c b/arch/mips/mm/c-r4k.c
index d1b9da3..5f9171d 100644
--- a/arch/mips/mm/c-r4k.c
+++ b/arch/mips/mm/c-r4k.c
@@ -345,6 +345,10 @@ static inline void local_r4k___flush_cache_all(void * args)
 	r4k_blast_scache();
 	return;
 #endif
+
+	if (cpu_has_coherent_cache)
+		return;
+
 	r4k_blast_dcache();
 	r4k_blast_icache();
 
@@ -406,8 +410,12 @@ static inline void local_r4k_flush_cache_range(void * args)
 static void r4k_flush_cache_range(struct vm_area_struct *vma,
 	unsigned long start, unsigned long end)
 {
-	int exec = vma->vm_flags & VM_EXEC;
+	int exec __maybe_unused;
+
+	if (cpu_has_coherent_cache)
+		return;
 
+	exec = vma->vm_flags & VM_EXEC;
 	if (cpu_has_dc_aliases || (exec && !cpu_has_ic_fills_f_dc))
 		r4k_on_each_cpu(local_r4k_flush_cache_range, vma);
 }
@@ -527,7 +535,10 @@ static inline void local_r4k_flush_cache_page(void *args)
 static void r4k_flush_cache_page(struct vm_area_struct *vma,
 	unsigned long addr, unsigned long pfn)
 {
-	struct flush_cache_page_args args;
+	struct flush_cache_page_args args __maybe_unused;
+
+	if (cpu_has_coherent_cache)
+		return;
 
 	args.vma = vma;
 	args.addr = addr;
@@ -543,6 +554,9 @@ static inline void local_r4k_flush_data_cache_page(void * addr)
 
 static void r4k_flush_data_cache_page(unsigned long addr)
 {
+	if (cpu_has_coherent_cache)
+		return;
+
 	if (in_atomic())
 		local_r4k_flush_data_cache_page((void *)addr);
 	else
@@ -701,6 +715,9 @@ static void local_r4k_flush_cache_sigtramp(void * arg)
 
 static void r4k_flush_cache_sigtramp(unsigned long addr)
 {
+	if (cpu_has_coherent_cache)
+		return;
+
 	r4k_on_each_cpu(local_r4k_flush_cache_sigtramp, (void *) addr);
 }
 
-- 
1.7.7.3