MIPS: CPC: Map registers using DT in mips_cpc_default_phys_base()

Reading mips_cpc_base value from the DT allows each platform to
define it according to its needs. This is especially convenient
for MIPS_GENERIC kernel where this kind of information should be
determined in runtime.

Use mti,mips-cpc compatible string with just a reg property to
specify the register location for your platform.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Signed-off-by: Miodrag Dinic <miodrag.dinic@mips.com>
Signed-off-by: Aleksandar Markovic <aleksandar.markovic@mips.com>
Cc: linux-mips@linux-mips.org
Cc: Ralf Baechle <ralf@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/18513/Signed-off-by: James Hogan <jhogan@kernel.org>

arch/mips/kernel/mips-cpc.c

@@ -10,6 +10,8 @@
 
 #include <linux/errno.h>
 #include <linux/percpu.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
 #include <linux/spinlock.h>
 
 #include <asm/mips-cps.h>
@@ -22,6 +24,17 @@ static DEFINE_PER_CPU_ALIGNED(unsigned long, cpc_core_lock_flags);
 
 phys_addr_t __weak mips_cpc_default_phys_base(void)
 {
+	struct device_node *cpc_node;
+	struct resource res;
+	int err;
+
+	cpc_node = of_find_compatible_node(of_root, NULL, "mti,mips-cpc");
+	if (cpc_node) {
+		err = of_address_to_resource(cpc_node, 0, &res);
+		if (!err)
+			return res.start;
+	}
+
 	return 0;
 }