MIPS: Probe cache line sizes once during boot

Rather than probing the cache line sizes on every call of any cache
maintenance function, probe them once during boot & store the values in
the global data structure for later use. This will reduce the overhead
of the cache maintenance functions, which isn't a big deal yet but
becomes more important once L2 caches which may expose their properties
via coprocessor 2 or the CM are supported.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>

arch/mips/cpu/cpu.c

@@ -8,6 +8,7 @@
 #include <common.h>
 #include <command.h>
 #include <linux/compiler.h>
+#include <asm/cache.h>
 #include <asm/mipsregs.h>
 #include <asm/reboot.h>
 
@@ -35,3 +36,9 @@ void write_one_tlb(int index, u32 pagemask, u32 hi, u32 low0, u32 low1)
 	write_c0_index(index);
 	tlb_write_indexed();
 }
+
+int arch_cpu_init(void)
+{
+	mips_cache_probe();
+	return 0;
+}

arch/mips/include/asm/cache.h

@@ -19,4 +19,13 @@
  */
 #define CONFIG_SYS_CACHELINE_SIZE ARCH_DMA_MINALIGN
 
+/**
+ * mips_cache_probe() - Probe the properties of the caches
+ *
+ * Call this to probe the properties such as line sizes of the caches
+ * present in the system, if any. This must be done before cache maintenance
+ * functions such as flush_cache may be called.
+ */
+void mips_cache_probe(void);
+
 #endif /* __MIPS_CACHE_H__ */

arch/mips/include/asm/global_data.h

@@ -21,6 +21,10 @@ struct arch_global_data {
 	unsigned long rev;
 	unsigned long ver;
 #endif
+#ifdef CONFIG_SYS_CACHE_SIZE_AUTO
+	unsigned short l1i_line_size;
+	unsigned short l1d_line_size;
+#endif
 };
 
 #include <asm-generic/global_data.h>

arch/mips/lib/cache.c

@@ -9,32 +9,39 @@
 #include <asm/cacheops.h>
 #include <asm/mipsregs.h>
 
-static inline unsigned long icache_line_size(void)
-{
-	unsigned long conf1, il;
+DECLARE_GLOBAL_DATA_PTR;
 
-	if (!config_enabled(CONFIG_SYS_CACHE_SIZE_AUTO))
-		return CONFIG_SYS_ICACHE_LINE_SIZE;
+void mips_cache_probe(void)
+{
+#ifdef CONFIG_SYS_CACHE_SIZE_AUTO
+	unsigned long conf1, il, dl;
 
 	conf1 = read_c0_config1();
+
 	il = (conf1 & MIPS_CONF1_IL) >> MIPS_CONF1_IL_SHF;
-	if (!il)
-		return 0;
-	return 2 << il;
+	dl = (conf1 & MIPS_CONF1_DL) >> MIPS_CONF1_DL_SHF;
+
+	gd->arch.l1i_line_size = il ? (2 << il) : 0;
+	gd->arch.l1d_line_size = dl ? (2 << dl) : 0;
+#endif
+}
+
+static inline unsigned long icache_line_size(void)
+{
+#ifdef CONFIG_SYS_CACHE_SIZE_AUTO
+	return gd->arch.l1i_line_size;
+#else
+	return CONFIG_SYS_ICACHE_LINE_SIZE;
+#endif
 }
 
 static inline unsigned long dcache_line_size(void)
 {
-	unsigned long conf1, dl;
-
-	if (!config_enabled(CONFIG_SYS_CACHE_SIZE_AUTO))
-		return CONFIG_SYS_DCACHE_LINE_SIZE;
-
-	conf1 = read_c0_config1();
-	dl = (conf1 & MIPS_CONF1_DL) >> MIPS_CONF1_DL_SHF;
-	if (!dl)
-		return 0;
-	return 2 << dl;
+#ifdef CONFIG_SYS_CACHE_SIZE_AUTO
+	return gd->arch.l1d_line_size;
+#else
+	return CONFIG_SYS_DCACHE_LINE_SIZE;
+#endif
 }
 
 #define cache_loop(start, end, lsize, ops...) do {			\