ppc/85xx: Add a simple function to search the TLB

Allow us to search the TLB array based on an address.  This is useful
if we want to change an entry but dont know where it happens to be
located.

For example, the boot page mapping we use on MP or the flash TLB that
we change the WIMGE settings for after we've relocated.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

cpu/mpc85xx/tlb.c

@@ -106,6 +106,33 @@ void init_tlbs(void)
 	return ;
 }
 
+static void tlbsx (const volatile unsigned *addr)
+{
+	__asm__ __volatile__ ("tlbsx 0,%0" : : "r" (addr), "m" (*addr));
+}
+
+/* return -1 if we didn't find anything */
+int find_tlb_idx(void *addr, u8 tlbsel)
+{
+	u32 _mas0, _mas1;
+
+	/* zero out Search PID, AS */
+	mtspr(MAS6, 0);
+
+	tlbsx(addr);
+
+	_mas0 = mfspr(MAS0);
+	_mas1 = mfspr(MAS1);
+
+	/* we found something, and its in the TLB we expect */
+	if ((MAS1_VALID & _mas1) &&
+		(MAS0_TLBSEL(tlbsel) == (_mas0 & MAS0_TLBSEL_MSK))) {
+		return ((_mas0 & MAS0_ESEL_MSK) >> 16);
+	}
+
+	return -1;
+}
+
 #ifdef CONFIG_ADDR_MAP
 void init_addr_map(void)
 {

include/asm-ppc/mmu.h

@@ -387,8 +387,10 @@ extern void print_bats(void);
  * FSL Book-E support
  */
 
-#define MAS0_TLBSEL(x)	((x << 28) & 0x30000000)
-#define MAS0_ESEL(x)	((x << 16) & 0x0FFF0000)
+#define MAS0_TLBSEL_MSK	0x30000000
+#define MAS0_TLBSEL(x)	((x << 28) & MAS0_TLBSEL_MSK)
+#define MAS0_ESEL_MSK	0x0FFF0000
+#define MAS0_ESEL(x)	((x << 16) & MAS0_ESEL_MSK)
 #define MAS0_NV(x)	((x) & 0x00000FFF)
 
 #define MAS1_VALID	0x80000000
@@ -474,6 +476,7 @@ extern void set_tlb(u8 tlb, u32 epn, u64 rpn,
 extern void disable_tlb(u8 esel);
 extern void invalidate_tlb(u8 tlb);
 extern void init_tlbs(void);
+extern int find_tlb_idx(void *addr, u8 tlbsel);
 
 extern unsigned int setup_ddr_tlbs(unsigned int memsize_in_meg);