MIPS: Decode c0_config4 for large TLBs.

For processors that have more than 64 TLBs, we need to decode both
config1 and config4 to determine the total number TLBs.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/866/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

2 files changed, 19 insertions, 0 deletions

diff --git a/arch/mips/include/asm/mipsregs.h b/arch/mips/include/asm/mipsregs.h
index f4ab3139d737..edda1daf742f 100644
--- a/arch/mips/include/asm/mipsregs.h
+++ b/arch/mips/include/asm/mipsregs.h
@@ -576,6 +576,10 @@
 #define MIPS_CONF3_DSP          (_ULCAST_(1) << 10)
 #define MIPS_CONF3_ULRI         (_ULCAST_(1) << 13)
 
+#define MIPS_CONF4_MMUSIZEEXT   (_ULCAST_(255) << 0)
+#define MIPS_CONF4_MMUEXTDEF    (_ULCAST_(3) << 14)
+#define MIPS_CONF4_MMUEXTDEF_MMUSIZEEXT (_ULCAST_(1) << 14)
+
 #define MIPS_CONF7_WII          (_ULCAST_(1) << 31)
 
 #define MIPS_CONF7_RPS          (_ULCAST_(1) << 2)
diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
index 758ad426c57f..323395081b2a 100644
--- a/arch/mips/kernel/cpu-probe.c
+++ b/arch/mips/kernel/cpu-probe.c
@@ -700,6 +700,19 @@ static inline unsigned int decode_config3(struct cpuinfo_mips *c)
         return config3 & MIPS_CONF_M;
 }
 
+static inline unsigned int decode_config4(struct cpuinfo_mips *c)
+{
+        unsigned int config4;
+
+        config4 = read_c0_config4();
+
+        if ((config4 & MIPS_CONF4_MMUEXTDEF) == MIPS_CONF4_MMUEXTDEF_MMUSIZEEXT
+            && cpu_has_tlb)
+                c->tlbsize += (config4 & MIPS_CONF4_MMUSIZEEXT) * 0x40;
+
+        return config4 & MIPS_CONF_M;
+}
+
 static void __cpuinit decode_configs(struct cpuinfo_mips *c)
 {
         int ok;
@@ -718,6 +731,8 @@ static void __cpuinit decode_configs(struct cpuinfo_mips *c)
                 ok = decode_config2(c);
         if (ok)
                 ok = decode_config3(c);
+        if (ok)
+                ok = decode_config4(c);
 
         mips_probe_watch_registers(c);
 }