[PATCH V4 1/6] 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>
---
 arch/mips/Kconfig                                  |    3 ++
 arch/mips/include/asm/cpu-features.h               |    3 ++
 .../asm/mach-loongson/cpu-feature-overrides.h      |    1 +
 arch/mips/mm/c-r4k.c                               |   21 ++++++++++++++++++++
 4 files changed, 28 insertions(+), 0 deletions(-)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 9e8317e..07bb4d9 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -1621,6 +1621,7 @@ config CPU_BMIPS5000
 config SYS_HAS_CPU_LOONGSON3
 	bool
 	select CPU_SUPPORTS_CPUFREQ
+	select CPU_SUPPORTS_COHERENT_CACHE
 
 config SYS_HAS_CPU_LOONGSON2E
 	bool
@@ -1784,6 +1785,8 @@ config CPU_SUPPORTS_HUGEPAGES
 	bool
 config CPU_SUPPORTS_UNCACHED_ACCELERATED
 	bool
+config CPU_SUPPORTS_COHERENT_CACHE
+	bool
 config MIPS_PGD_C0_CONTEXT
 	bool
 	default y if 64BIT && CPU_MIPSR2 && !CPU_XLP
diff --git a/arch/mips/include/asm/cpu-features.h b/arch/mips/include/asm/cpu-features.h
index 2897cfa..f20bf5a 100644
--- a/arch/mips/include/asm/cpu-features.h
+++ b/arch/mips/include/asm/cpu-features.h
@@ -148,6 +148,9 @@
 #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
 #ifndef cpu_has_local_ebase
 #define cpu_has_local_ebase	1
 #endif
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 6d69332..7efb191 100644
--- a/arch/mips/include/asm/mach-loongson/cpu-feature-overrides.h
+++ b/arch/mips/include/asm/mach-loongson/cpu-feature-overrides.h
@@ -58,5 +58,6 @@
 #define cpu_has_local_ebase	0
 
 #define cpu_has_wsbh		IS_ENABLED(CONFIG_CPU_LOONGSON3)
+#define cpu_has_coherent_cache	IS_ENABLED(CONFIG_CPU_SUPPORTS_COHERENT_CACHE)
 
 #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 dd261df..5131b4d 100644
--- a/arch/mips/mm/c-r4k.c
+++ b/arch/mips/mm/c-r4k.c
@@ -420,6 +420,9 @@ static void r4k_blast_scache_setup(void)
 
 static inline void local_r4k___flush_cache_all(void * args)
 {
+	if (cpu_has_coherent_cache)
+		return;
+
 	switch (current_cpu_type()) {
 	case CPU_LOONGSON2:
 	case CPU_LOONGSON3:
@@ -447,6 +450,9 @@ static inline void local_r4k___flush_cache_all(void * args)
 
 static void r4k___flush_cache_all(void)
 {
+	if (cpu_has_coherent_cache)
+		return;
+
 	r4k_on_each_cpu(local_r4k___flush_cache_all, NULL);
 }
 
@@ -493,6 +499,9 @@ static void r4k_flush_cache_range(struct vm_area_struct *vma,
 {
 	int exec = vma->vm_flags & VM_EXEC;
 
+	if (cpu_has_coherent_cache)
+		return;
+
 	if (cpu_has_dc_aliases || (exec && !cpu_has_ic_fills_f_dc))
 		r4k_on_each_cpu(local_r4k_flush_cache_range, vma);
 }
@@ -616,6 +625,9 @@ static void r4k_flush_cache_page(struct vm_area_struct *vma,
 {
 	struct flush_cache_page_args args;
 
+	if (cpu_has_coherent_cache)
+		return;
+
 	args.vma = vma;
 	args.addr = addr;
 	args.pfn = pfn;
@@ -625,11 +637,17 @@ static void r4k_flush_cache_page(struct vm_area_struct *vma,
 
 static inline void local_r4k_flush_data_cache_page(void * addr)
 {
+	if (cpu_has_coherent_cache)
+		return;
+
 	r4k_blast_dcache_page((unsigned long) 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
@@ -814,6 +832,9 @@ 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