MIPS: Add CPC probe, access functions

This patch introduces code to probe for a MIPS Cluster Power Controller
& accessor functions to allow for easy register access. This support
code will be used by a subsequent patch.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6361/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/Makefile

@@ -104,6 +104,7 @@ obj-$(CONFIG_HW_PERF_EVENTS)	+= perf_event_mipsxx.o
 obj-$(CONFIG_JUMP_LABEL)	+= jump_label.o
 
 obj-$(CONFIG_MIPS_CM)		+= mips-cm.o
+obj-$(CONFIG_MIPS_CPC)		+= mips-cpc.o
 
 #
 # DSP ASE supported for MIPS32 or MIPS64 Release 2 cores only. It is not

arch/mips/kernel/mips-cpc.c

@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2013 Imagination Technologies
+ * Author: Paul Burton <paul.burton@imgtec.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation;  either version 2 of the  License, or (at your
+ * option) any later version.
+ */
+
+#include <linux/errno.h>
+
+#include <asm/mips-cm.h>
+#include <asm/mips-cpc.h>
+
+void __iomem *mips_cpc_base;
+
+phys_t __weak mips_cpc_phys_base(void)
+{
+	u32 cpc_base;
+
+	if (!mips_cm_present())
+		return 0;
+
+	if (!(read_gcr_cpc_status() & CM_GCR_CPC_STATUS_EX_MSK))
+		return 0;
+
+	/* If the CPC is already enabled, leave it so */
+	cpc_base = read_gcr_cpc_base();
+	if (cpc_base & CM_GCR_CPC_BASE_CPCEN_MSK)
+		return cpc_base & CM_GCR_CPC_BASE_CPCBASE_MSK;
+
+	/* Otherwise, give it the default address & enable it */
+	cpc_base = mips_cpc_default_phys_base();
+	write_gcr_cpc_base(cpc_base | CM_GCR_CPC_BASE_CPCEN_MSK);
+	return cpc_base;
+}
+
+int mips_cpc_probe(void)
+{
+	phys_t addr;
+
+	addr = mips_cpc_phys_base();
+	if (!addr)
+		return -ENODEV;
+
+	mips_cpc_base = ioremap_nocache(addr, 0x8000);
+	if (!mips_cpc_base)
+		return -ENXIO;
+
+	return 0;
+}