[MIPS] Implement flush_cache()

We do Hit_Writeback_Inv_D and Hit_Invalidate_I. You might think that you
don't need to do Hit_Invalidate_I, but flush_cache() needs it since this
function is used not only in U-Boot specfic programs but also at loading
target binaries.

Signed-off-by: Shinya Kuribayashi <skuribay@ruby.dti.ne.jp>

cpu/mips/cpu.c

@@ -25,6 +25,17 @@
 #include <command.h>
 #include <asm/inca-ip.h>
 #include <asm/mipsregs.h>
+#include <asm/cacheops.h>
+
+#define cache_op(op,addr)						\
+	__asm__ __volatile__(						\
+	"	.set	push					\n"	\
+	"	.set	noreorder				\n"	\
+	"	.set	mips3\n\t				\n"	\
+	"	cache	%0, %1					\n"	\
+	"	.set	pop					\n"	\
+	:								\
+	: "i" (op), "R" (*(unsigned char *)(addr)))
 
 int do_reset(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
 {
@@ -41,6 +52,17 @@ int do_reset(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
 
 void flush_cache(ulong start_addr, ulong size)
 {
+	unsigned long lsize = CFG_CACHELINE_SIZE;
+	unsigned long addr = start_addr & ~(lsize - 1);
+	unsigned long aend = (start_addr + size - 1) & ~(lsize - 1);
+
+	while (1) {
+		cache_op(Hit_Writeback_Inv_D, start_addr);
+		cache_op(Hit_Invalidate_I, start_addr);
+		if (addr == aend)
+			break;
+		addr += lsize;
+	}
 }
 
 void write_one_tlb(int index, u32 pagemask, u32 hi, u32 low0, u32 low1)