MIPS: OCTEON: Implement the core-16057 workaround

Disable ICache prefetch for certian Octeon II processors.
Signed-off-by: NDavid Daney <david.daney@cavium.com>
Signed-off-by: NAleksey Makarov <aleksey.makarov@auriga.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/8938/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/mach-cavium-octeon/kernel-entry-init.h

@@ -63,6 +63,28 @@
 	li	v1, ~(7 << 7)
 	and	v0, v0, v1
 	ori	v0, v0, (6 << 7)
+
+	mfc0	v1, CP0_PRID_REG
+	and	t1, v1, 0xfff8
+	xor	t1, t1, 0x9000		# 63-P1
+	beqz	t1, 4f
+	and	t1, v1, 0xfff8
+	xor	t1, t1, 0x9008		# 63-P2
+	beqz	t1, 4f
+	and	t1, v1, 0xfff8
+	xor	t1, t1, 0x9100		# 68-P1
+	beqz	t1, 4f
+	and	t1, v1, 0xff00
+	xor	t1, t1, 0x9200		# 66-PX
+	bnez	t1, 5f			# Skip WAR for others.
+	and	t1, v1, 0x00ff
+	slti	t1, t1, 2		# 66-P1.2 and later good.
+	beqz	t1, 5f
+
+4:	# core-16057 work around
+	or	v0, v0, 0x2000		# Set IPREF bit.
+
+5:	# No core-16057 work around
 	# Write the cavium control register
 	dmtc0	v0, CP0_CVMCTL_REG
 	sync