ARM: Add Krait L2 register accessor functions

Krait CPUs have a handful of L2 cache controller registers that
live behind a cp15 based indirection register. First you program
the indirection register (l2cpselr) to point the L2 'window'
register (l2cpdr) at what you want to read/write.  Then you
read/write the 'window' register to do what you want. The
l2cpselr register is not banked per-cpu so we must lock around
accesses to it to prevent other CPUs from re-pointing l2cpdr
underneath us.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Courtney Cavin <courtney.cavin@sonymobile.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

4 files changed, 82 insertions, 0 deletions

diff --git a/arch/arm/common/Kconfig b/arch/arm/common/Kconfig
index 4fb337ca0cb7..4e390fe25862 100644
--- a/arch/arm/common/Kconfig
+++ b/arch/arm/common/Kconfig
@@ -9,6 +9,9 @@ config DMABOUNCE
 	bool
 	select ZONE_DMA
 
+config KRAIT_L2_ACCESSORS
+	bool
+
 config SHARP_LOCOMO
 	bool
 
diff --git a/arch/arm/common/Makefile b/arch/arm/common/Makefile
index 14e592312033..0d61308e2dbc 100644
--- a/arch/arm/common/Makefile
+++ b/arch/arm/common/Makefile
@@ -9,6 +9,7 @@ obj-$(CONFIG_FIQ_GLUE)		+= fiq_glue.o fiq_glue_setup.o
 obj-$(CONFIG_ICST)		+= icst.o
 obj-$(CONFIG_SA1111)		+= sa1111.o
 obj-$(CONFIG_DMABOUNCE)		+= dmabounce.o
+obj-$(CONFIG_KRAIT_L2_ACCESSORS) += krait-l2-accessors.o
 obj-$(CONFIG_SHARP_LOCOMO)	+= locomo.o
 obj-$(CONFIG_SHARP_PARAM)	+= sharpsl_param.o
 obj-$(CONFIG_SHARP_SCOOP)	+= scoop.o
diff --git a/arch/arm/common/krait-l2-accessors.c b/arch/arm/common/krait-l2-accessors.c
new file mode 100644
index 000000000000..5d514bbc88a6
--- /dev/null
+++ b/arch/arm/common/krait-l2-accessors.c
@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2011-2013, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/spinlock.h>
+#include <linux/export.h>
+
+#include <asm/barrier.h>
+#include <asm/krait-l2-accessors.h>
+
+static DEFINE_RAW_SPINLOCK(krait_l2_lock);
+
+void krait_set_l2_indirect_reg(u32 addr, u32 val)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&krait_l2_lock, flags);
+	/*
+	 * Select the L2 window by poking l2cpselr, then write to the window
+	 * via l2cpdr.
+	 */
+	asm volatile ("mcr p15, 3, %0, c15, c0, 6 @ l2cpselr" : : "r" (addr));
+	isb();
+	asm volatile ("mcr p15, 3, %0, c15, c0, 7 @ l2cpdr" : : "r" (val));
+	isb();
+
+	raw_spin_unlock_irqrestore(&krait_l2_lock, flags);
+}
+EXPORT_SYMBOL(krait_set_l2_indirect_reg);
+
+u32 krait_get_l2_indirect_reg(u32 addr)
+{
+	u32 val;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&krait_l2_lock, flags);
+	/*
+	 * Select the L2 window by poking l2cpselr, then read from the window
+	 * via l2cpdr.
+	 */
+	asm volatile ("mcr p15, 3, %0, c15, c0, 6 @ l2cpselr" : : "r" (addr));
+	isb();
+	asm volatile ("mrc p15, 3, %0, c15, c0, 7 @ l2cpdr" : "=r" (val));
+
+	raw_spin_unlock_irqrestore(&krait_l2_lock, flags);
+
+	return val;
+}
+EXPORT_SYMBOL(krait_get_l2_indirect_reg);
diff --git a/arch/arm/include/asm/krait-l2-accessors.h b/arch/arm/include/asm/krait-l2-accessors.h
new file mode 100644
index 000000000000..48fe5527bc01
--- /dev/null
+++ b/arch/arm/include/asm/krait-l2-accessors.h
@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2011-2013, The Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __ASMARM_KRAIT_L2_ACCESSORS_H
+#define __ASMARM_KRAIT_L2_ACCESSORS_H
+
+extern void krait_set_l2_indirect_reg(u32 addr, u32 val);
+extern u32 krait_get_l2_indirect_reg(u32 addr);
+
+#endif