MIPS: smp-cps: Disable coherence setup for unsupported ISA

We don't know how to do coherence setup on ISA before MIPS
Release 1.

As CPS support only servers simulation purpose on those cores,
and simulators are always coherent, just disable initialization
code and provide user a warning in case coherence is not setup
properly.
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/kernel/cps-vec.S

@@ -116,6 +116,8 @@ not_nmi:
 	li	t0, ST0_CU1 | ST0_CU0 | ST0_BEV | STATUS_BITDEPS
 	mtc0	t0, CP0_STATUS
 
+	/* We don't know how to do coherence setup on earlier ISA */
+#if MIPS_ISA_REV > 0
 	/* Skip cache & coherence setup if we're already coherent */
 	lw	s7, GCR_CL_COHERENCE_OFS(s1)
 	bnez	s7, 1f
@@ -129,6 +131,7 @@ not_nmi:
 	li	t0, 0xff
 	sw	t0, GCR_CL_COHERENCE_OFS(s1)
 	ehb
+#endif /* MIPS_ISA_REV > 0 */
 
 	/* Set Kseg0 CCA to that in s0 */
 1:	mfc0	t0, CP0_CONFIG
@@ -515,6 +518,7 @@ LEAF(mips_cps_boot_vpes)
 	 nop
 	END(mips_cps_boot_vpes)
 
+#if MIPS_ISA_REV > 0
 LEAF(mips_cps_cache_init)
 	/*
 	 * Clear the bits used to index the caches. Note that the architecture
@@ -588,6 +592,7 @@ dcache_done:
 	jr	ra
 	 nop
 	END(mips_cps_cache_init)
+#endif /* MIPS_ISA_REV > 0 */
 
 #if defined(CONFIG_MIPS_CPS_PM) && defined(CONFIG_CPU_PM)
 

arch/mips/kernel/smp-cps.c

@@ -361,6 +361,8 @@ static int cps_boot_secondary(int cpu, struct task_struct *idle)
 
 static void cps_init_secondary(void)
 {
+	int core = cpu_core(&current_cpu_data);
+
 	/* Disable MT - we only want to run 1 TC per VPE */
 	if (cpu_has_mipsmt)
 		dmt();
@@ -376,6 +378,9 @@ static void cps_init_secondary(void)
 		BUG_ON(ident != mips_cm_vp_id(smp_processor_id()));
 	}
 
+	if (core > 0 && !read_gcr_cl_coherence())
+		pr_warn("Core %u is not in coherent domain\n", core);
+
 	if (cpu_has_veic)
 		clear_c0_status(ST0_IM);
 	else