MIPS: Add platform callback before initializing the L2 cache

Allow platforms to perform platform-specific steps before configuring
the L2 cache. This is necessary for platforms with CM3 since the L2
parameters no longer live in the Config2 register.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/10642/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/mips-cm.c

@@ -81,6 +81,13 @@ int mips_cm_probe(void)
 	phys_addr_t addr;
 	u32 base_reg;
 
+	/*
+	 * No need to probe again if we have already been
+	 * here before.
+	 */
+	if (mips_cm_base)
+		return 0;
+
 	addr = mips_cm_phys_base();
 	BUG_ON((addr & CM_GCR_BASE_GCRBASE_MSK) != addr);
 	if (!addr)

arch/mips/mm/sc-mips.c

@@ -123,6 +123,10 @@ static int __init mips_sc_probe_cm3(void)
 	return 1;
 }
 
+void __weak platform_early_l2_init(void)
+{
+}
+
 static inline int __init mips_sc_probe(void)
 {
 	struct cpuinfo_mips *c = &current_cpu_data;
@@ -132,6 +136,12 @@ static inline int __init mips_sc_probe(void)
 	/* Mark as not present until probe completed */
 	c->scache.flags |= MIPS_CACHE_NOT_PRESENT;
 
+	/*
+	 * Do we need some platform specific probing before
+	 * we configure L2?
+	 */
+	platform_early_l2_init();
+
 	if (mips_cm_revision() >= CM_REV_CM3)
 		return mips_sc_probe_cm3();
 

arch/mips/mti-malta/malta-init.c

@@ -303,3 +303,10 @@ void __init prom_init(void)
 	if (!register_vsmp_smp_ops())
 		return;
 }
+
+void platform_early_l2_init(void)
+{
+	/* L2 configuration lives in the CM3 */
+	if (mips_cm_revision() >= CM_REV_CM3)
+		mips_cm_probe();
+}