MIPS: Allow RIXI to be used on non-R2 or R6 cores

Some processors, like Broadcom's BMIPS4380 and BMIPS5000 support RIXI and the
"rotr" instruction, which can be used to get a slightly more efficient page
table layout.

Introduce a CONFIG_CPU_HAS_RIXI such that those cores can benefit from this
feature. Perform the conditional check updates where relevant.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Cc: john@phrozen.org
Cc: cernekee@gmail.com
Cc: jon.fraser@broadcom.com
Cc: pgynther@google.com
Cc: paul.burton@imgtec.com
Cc: ddaney.cavm@gmail.com
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/12505/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/Kconfig

@@ -1996,11 +1996,13 @@ config CPU_MIPSR1
 config CPU_MIPSR2
 	bool
 	default y if CPU_MIPS32_R2 || CPU_MIPS64_R2 || CPU_CAVIUM_OCTEON
+	select CPU_HAS_RIXI
 	select MIPS_SPRAM
 
 config CPU_MIPSR6
 	bool
 	default y if CPU_MIPS32_R6 || CPU_MIPS64_R6
+	select CPU_HAS_RIXI
 	select HAVE_ARCH_BITREVERSE
 	select MIPS_ASID_BITS_VARIABLE
 	select MIPS_SPRAM
@@ -2421,6 +2423,9 @@ config CPU_HAS_WB
 config XKS01
 	bool
 
+config CPU_HAS_RIXI
+	bool
+
 #
 # Vectored interrupt mode is an R2 feature
 #

arch/mips/include/asm/pgtable-bits.h

@@ -104,7 +104,7 @@ enum pgtable_bits {
 enum pgtable_bits {
 	/* Used only by software (masked out before writing EntryLo*) */
 	_PAGE_PRESENT_SHIFT,
-#if !defined(CONFIG_CPU_MIPSR2) && !defined(CONFIG_CPU_MIPSR6)
+#if !defined(CONFIG_CPU_HAS_RIXI)
 	_PAGE_NO_READ_SHIFT,
 #endif
 	_PAGE_WRITE_SHIFT,
@@ -115,7 +115,7 @@ enum pgtable_bits {
 #endif
 
 	/* Used by TLB hardware (placed in EntryLo*) */
-#if defined(CONFIG_CPU_MIPSR2) || defined(CONFIG_CPU_MIPSR6)
+#if defined(CONFIG_CPU_HAS_RIXI)
 	_PAGE_NO_EXEC_SHIFT,
 	_PAGE_NO_READ_SHIFT,
 #endif
@@ -139,7 +139,7 @@ enum pgtable_bits {
 /* Used by TLB hardware (placed in EntryLo*) */
 #if defined(CONFIG_XPA)
 # define _PAGE_NO_EXEC		(1 << _PAGE_NO_EXEC_SHIFT)
-#elif defined(CONFIG_CPU_MIPSR2) || defined(CONFIG_CPU_MIPSR6)
+#elif defined(CONFIG_CPU_HAS_RIXI)
 # define _PAGE_NO_EXEC		(cpu_has_rixi ? (1 << _PAGE_NO_EXEC_SHIFT) : 0)
 #endif
 #define _PAGE_NO_READ		(1 << _PAGE_NO_READ_SHIFT)
@@ -180,7 +180,7 @@ enum pgtable_bits {
  */
 static inline uint64_t pte_to_entrylo(unsigned long pte_val)
 {
-#if defined(CONFIG_CPU_MIPSR2) || defined(CONFIG_CPU_MIPSR6)
+#ifdef CONFIG_CPU_HAS_RIXI
 	if (cpu_has_rixi) {
 		int sa;
 #ifdef CONFIG_32BIT