MIPS: perf: Add cpu feature bit for PCI (performance counter interrupt)

The PCI (Program Counter Interrupt) bit in the "cause" register
is mandatory for MIPS32R2 cores, but has also been added to some R1
cores (BMIPS5000). This change adds a cpu feature bit to make it
easier to check for and use this feature.

Signed-off-by: Al Cooper <alcooperx@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/4106/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/include/asm/mipsregs.h b/arch/mips/include/asm/mipsregs.h
index 528fda1..04d7560 100644
--- a/arch/mips/include/asm/mipsregs.h
+++ b/arch/mips/include/asm/mipsregs.h
@@ -458,6 +458,8 @@
 #define  CAUSEF_IP7		(_ULCAST_(1)   << 15)
 #define  CAUSEB_IV		23
 #define  CAUSEF_IV		(_ULCAST_(1)   << 23)
+#define  CAUSEB_PCI		26
+#define  CAUSEF_PCI		(_ULCAST_(1)   << 26)
 #define  CAUSEB_CE		28
 #define  CAUSEF_CE		(_ULCAST_(3)   << 28)
 #define  CAUSEB_TI		30