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

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Message-ID: <664089d4-b30d-99bb-2021-12128b2895ba@codeaurora.org>
Date:   Fri, 25 May 2018 11:10:11 +0530
From:   Sricharan R <sricharan@...eaurora.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     robh@...nel.org, viresh.kumar@...aro.org, mark.rutland@....com,
        mturquette@...libre.com, sboyd@...eaurora.org,
        linux@...linux.org.uk, andy.gross@...aro.org,
        david.brown@...aro.org, rjw@...ysocki.net,
        linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
        linux-pm@...r.kernel.org, linux@....linux.org.uk
Subject: Re: [PATCH v9 01/15] ARM: Add Krait L2 register accessor functions

Hi Bjorn,

On 5/24/2018 11:09 PM, Bjorn Andersson wrote:
> On Tue 06 Mar 06:38 PST 2018, Sricharan R wrote:
> 
>> From: Stephen Boyd <sboyd@...eaurora.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@....com>
>> Cc: Russell King <linux@....linux.org.uk>
>> Signed-off-by: Stephen Boyd <sboyd@...eaurora.org>
> 
> This should have your signed-off-by here as well.
> 

 ok.

> Apart from that:
> 
> Acked-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> 

 Thanks.

Regards,
 Sricharan


> 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
>> -- 
>> QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation
>>

-- 
"QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation