From patchwork Fri Dec  8 09:42:19 2017
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Subject: [v4,01/12] ARM: Add Krait L2 register accessor functions
From: Sricharan R <sricharan@codeaurora.org>
X-Patchwork-Id: 10102101
Message-Id: <1512726150-7204-2-git-send-email-sricharan@codeaurora.org>
To: mturquette@baylibre.com, sboyd@codeaurora.org,
 devicetree@vger.kernel.org, linux-pm@vger.kernel.org,
 linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org,
 viresh.kumar@linaro.org, linux-arm-kernel@lists.infradead.org
Cc: sricharan@codeaurora.org, Mark Rutland <mark.rutland@arm.com>,
 Russell King <linux@arm.linux.org.uk>,
 Courtney Cavin <courtney.cavin@sonymobile.com>
Date: Fri,  8 Dec 2017 15:12:19 +0530

From: Stephen Boyd <sboyd@codeaurora.org>

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>
---
 arch/arm/common/Kconfig                   |  3 ++
 arch/arm/common/Makefile                  |  1 +
 arch/arm/common/krait-l2-accessors.c      | 58 +++++++++++++++++++++++++++++++
 arch/arm/include/asm/krait-l2-accessors.h | 20 +++++++++++
 4 files changed, 82 insertions(+)
 create mode 100644 arch/arm/common/krait-l2-accessors.c
 create mode 100644 arch/arm/include/asm/krait-l2-accessors.h

--- 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
 
--- 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
--- /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);
--- /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
