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>
Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Sricharan R <sricharan@codeaurora.org>
Tested-by: Craig Tatlor <ctatlor97@gmail.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

diff --git a/arch/arm/common/Kconfig b/arch/arm/common/Kconfig
index e5ad0708849a2f57d14d6e1f8141f6469d44aeeb..c8e198631d4182511d1bb3dee008ceae4c01f4d2 100644 (file)
--- a/arch/arm/common/Kconfig
+++ b/arch/arm/common/Kconfig
@@ -7,6 +7,9 @@ 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 3157be413297e5d22ad3174e2082b5199fc3083c..219a260bbe5f78abec23091e7ad07a7b1e992624 100644 (file)
--- a/arch/arm/common/Makefile
+++ b/arch/arm/common/Makefile
@@ -7,6 +7,7 @@ obj-y                           += firmware.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 (file)
index 0000000..9a97dda
--- /dev/null
+++ b/arch/arm/common/krait-l2-accessors.c
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2018, The Linux Foundation. All rights reserved.
+
+#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 (file)
index 0000000..a5f2cdd
--- /dev/null
+++ b/arch/arm/include/asm/krait-l2-accessors.h
@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#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