MIPS: For Cavium OCTEON set hwrena and lazily restore CP2 state.

If on Cavium, be aware of cop2 and hwrena during do_cpu().
Signed-off-by: Tomaso Paoletti <tpaoletti@caviumnetworks.com>
Signed-off-by: Paul Gortmaker <Paul.Gortmaker@windriver.com>
Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/traps.c

@@ -47,6 +47,7 @@
 #include <asm/mmu_context.h>
 #include <asm/types.h>
 #include <asm/stacktrace.h>
+#include <asm/irq.h>
 
 extern void check_wait(void);
 extern asmlinkage void r4k_wait(void);
@@ -78,6 +79,10 @@ extern asmlinkage void handle_reserved(void);
 extern int fpu_emulator_cop1Handler(struct pt_regs *xcp,
 	struct mips_fpu_struct *ctx, int has_fpu);
 
+#ifdef CONFIG_CPU_CAVIUM_OCTEON
+extern asmlinkage void octeon_cop2_restore(struct octeon_cop2_state *task);
+#endif
+
 void (*board_be_init)(void);
 int (*board_be_handler)(struct pt_regs *regs, int is_fixup);
 void (*board_nmi_handler_setup)(void);
@@ -860,6 +865,7 @@ asmlinkage void do_cpu(struct pt_regs *regs)
 	unsigned int opcode;
 	unsigned int cpid;
 	int status;
+	unsigned long __maybe_unused flags;
 
 	die_if_kernel("do_cpu invoked from kernel context!", regs);
 
@@ -915,6 +921,17 @@ asmlinkage void do_cpu(struct pt_regs *regs)
 		return;
 
 	case 2:
+#ifdef CONFIG_CPU_CAVIUM_OCTEON
+		prefetch(&current->thread.cp2);
+		local_irq_save(flags);
+		KSTK_STATUS(current) |= ST0_CU2;
+		status = read_c0_status();
+		write_c0_status(status | ST0_CU2);
+		octeon_cop2_restore(&(current->thread.cp2));
+		write_c0_status(status & ~ST0_CU2);
+		local_irq_restore(flags);
+		return;
+#endif
 	case 3:
 		break;
 	}
@@ -1488,6 +1505,10 @@ void __cpuinit per_cpu_trap_init(void)
 		write_c0_hwrena(enable);
 	}
 
+#ifdef CONFIG_CPU_CAVIUM_OCTEON
+	write_c0_hwrena(0xc000000f); /* Octeon has register 30 and 31 */
+#endif
+
 #ifdef CONFIG_MIPS_MT_SMTC
 	if (!secondaryTC) {
 #endif /* CONFIG_MIPS_MT_SMTC */