Re: [PATCH v9 01/15] ARM: Add Krait L2 register accessor functions

[Bjorn Andersson <bjorn.andersson@linaro.org>]

On Tue 06 Mar 06:38 PST 2018, Sricharan R wrote:

> 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>
> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

This should have your signed-off-by here as well.

Apart from that:

Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>

Regards,
Bjorn

> ---
>  arch/arm/common/Kconfig                   |  3 ++
>  arch/arm/common/Makefile                  |  1 +
>  arch/arm/common/krait-l2-accessors.c      | 48 +++++++++++++++++++++++++++++++
>  arch/arm/include/asm/krait-l2-accessors.h | 10 +++++++
>  4 files changed, 62 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 e5ad070..c8e1986 100644
> --- 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 70b4a14..eec6cd1 100644
> --- 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
> 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
> index 0000000..dd7c474
> --- /dev/null
> +++ b/arch/arm/include/asm/krait-l2-accessors.h
> @@ -0,0 +1,10 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (c) 2018, The Linux Foundation. All rights reserved.
> +
> +#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
> -- 
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