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    Subject[RFC/PATCH 01/12] ARM: Add Krait L2 register accessor functions
    Date
    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.

    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

    diff --git a/arch/arm/common/Kconfig b/arch/arm/common/Kconfig
    index c3a4e9ceba34..9da52dc6260b 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 70b1eff477b3..6b2cddf6e8d0 100644
    --- a/arch/arm/common/Makefile
    +++ b/arch/arm/common/Makefile
    @@ -7,6 +7,7 @@ obj-y += firmware.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
    --
    The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
    hosted by The Linux Foundation


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