MIPS: Add support for FTLBs

The Fixed Page Size TLB (FTLB) is a set-associative dual entry TLB. Its
purpose is to reduce the number of TLB misses by increasing the effective
TLB size and keep the implementation complexity to minimum levels.
A supported core can have both VTLB and FTLB.

Reviewed-by: James Hogan <james.hogan@imgtec.com>
Reviewed-by: Paul Burton <paul.burton@imgtec.com>
Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Signed-off-by: John Crispin <blogic@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/6139/

arch/mips/mm/tlb-r4k.c

@@ -72,7 +72,7 @@ void local_flush_tlb_all(void)
 {
 	unsigned long flags;
 	unsigned long old_ctx;
-	int entry;
+	int entry, ftlbhighset;
 
 	ENTER_CRITICAL(flags);
 	/* Save old context and create impossible VPN2 value */
@@ -83,10 +83,21 @@ void local_flush_tlb_all(void)
 	entry = read_c0_wired();
 
 	/* Blast 'em all away. */
-	if (cpu_has_tlbinv && current_cpu_data.tlbsize) {
-		write_c0_index(0);
-		mtc0_tlbw_hazard();
-		tlbinvf();  /* invalidate VTLB */
+	if (cpu_has_tlbinv) {
+		if (current_cpu_data.tlbsizevtlb) {
+			write_c0_index(0);
+			mtc0_tlbw_hazard();
+			tlbinvf();  /* invalidate VTLB */
+		}
+		ftlbhighset = current_cpu_data.tlbsizevtlb +
+			current_cpu_data.tlbsizeftlbsets;
+		for (entry = current_cpu_data.tlbsizevtlb;
+		     entry < ftlbhighset;
+		     entry++) {
+			write_c0_index(entry);
+			mtc0_tlbw_hazard();
+			tlbinvf();  /* invalidate one FTLB set */
+		}
 	} else {
 		while (entry < current_cpu_data.tlbsize) {
 			/* Make sure all entries differ. */
@@ -134,7 +145,9 @@ void local_flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
 		start = round_down(start, PAGE_SIZE << 1);
 		end = round_up(end, PAGE_SIZE << 1);
 		size = (end - start) >> (PAGE_SHIFT + 1);
-		if (size <= current_cpu_data.tlbsize/2) {
+		if (size <= (current_cpu_data.tlbsizeftlbsets ?
+			     current_cpu_data.tlbsize / 8 :
+			     current_cpu_data.tlbsize / 2)) {
 			int oldpid = read_c0_entryhi();
 			int newpid = cpu_asid(cpu, mm);
 
@@ -173,7 +186,9 @@ void local_flush_tlb_kernel_range(unsigned long start, unsigned long end)
 	ENTER_CRITICAL(flags);
 	size = (end - start + (PAGE_SIZE - 1)) >> PAGE_SHIFT;
 	size = (size + 1) >> 1;
-	if (size <= current_cpu_data.tlbsize / 2) {
+	if (size <= (current_cpu_data.tlbsizeftlbsets ?
+		     current_cpu_data.tlbsize / 8 :
+		     current_cpu_data.tlbsize / 2)) {
 		int pid = read_c0_entryhi();
 
 		start &= (PAGE_MASK << 1);