MIPS: Octeon: Apply CN63XXP1 errata workarounds.

The CN63XXP1 needs a couple of workarounds to ensure memory is not written
in unexpected ways.

All PREF with hints in the range 0-4,6-24 are replaced with PREF 28.  We
pass a flag to the assembler to cover compiler generated code, and patch
uasm for the dynamically generated code.

The write buffer threshold is reduced to 4.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Patchwork: http://patchwork.linux-mips.org/patch/1672/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 19 insertions, 1 deletions

diff --git a/arch/mips/mm/uasm.c b/arch/mips/mm/uasm.c
index d2647a4e012b..23afdebc8e5c 100644
--- a/arch/mips/mm/uasm.c
+++ b/arch/mips/mm/uasm.c
@@ -405,7 +405,6 @@ I_u1u2u3(_mfc0)
 I_u1u2u3(_mtc0)
 I_u2u1u3(_ori)
 I_u3u1u2(_or)
-I_u2s3u1(_pref)
 I_0(_rfe)
 I_u2s3u1(_sc)
 I_u2s3u1(_scd)
@@ -427,6 +426,25 @@ I_u1(_syscall);
 I_u1u2s3(_bbit0);
 I_u1u2s3(_bbit1);
 
+#ifdef CONFIG_CPU_CAVIUM_OCTEON
+#include <asm/octeon/octeon.h>
+void __uasminit uasm_i_pref(u32 **buf, unsigned int a, signed int b,
+                            unsigned int c)
+{
+        if (OCTEON_IS_MODEL(OCTEON_CN63XX_PASS1_X) && a <= 24 && a != 5)
+                /*
+                 * As per erratum Core-14449, replace prefetches 0-4,
+                 * 6-24 with 'pref 28'.
+                 */
+                build_insn(buf, insn_pref, c, 28, b);
+        else
+                build_insn(buf, insn_pref, c, a, b);
+}
+UASM_EXPORT_SYMBOL(uasm_i_pref);
+#else
+I_u2s3u1(_pref)
+#endif
+
 /* Handle labels. */
 void __uasminit uasm_build_label(struct uasm_label **lab, u32 *addr, int lid)
 {