linux-kernel - Re: [PATCH v3 1/6] ARM/ARM64: arch_timer: add macros for bits in control register

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Date:	Wed, 14 Aug 2013 10:03:48 +0100
From:	Marc Zyngier <marc.zyngier@....com>
To:	Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:	Sudeep KarkadaNagesha <sudeep.karkadanagesha@....com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	<linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v3 1/6] ARM/ARM64: arch_timer: add macros for bits in control register

Hi Daniel,

On 2013-08-14 09:50, Daniel Lezcano wrote:
> On 08/13/2013 07:29 PM, Sudeep KarkadaNagesha wrote:
>> From: Sudeep KarkadaNagesha <sudeep.karkadanagesha@....com>
>>
>> Add macros to describe the bitfields in the ARM architected timer
>> control register to make code easy to understand.
>>
>> Cc: Catalin Marinas <catalin.marinas@....com>
>> Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
>> Reviewed-by: Will Deacon <will.deacon@....com>
>> Signed-off-by: Sudeep KarkadaNagesha <sudeep.karkadanagesha@....com>
>> ---
>>  arch/arm/include/asm/arch_timer.h    |  9 +++++++--
>>  arch/arm64/include/asm/arch_timer.h  | 12 ++++++++----
>>  include/clocksource/arm_arch_timer.h |  8 ++++++++
>>  3 files changed, 23 insertions(+), 6 deletions(-)
>>
>> diff --git a/arch/arm/include/asm/arch_timer.h 
>> b/arch/arm/include/asm/arch_timer.h
>> index e406d57..9ef74da 100644
>> --- a/arch/arm/include/asm/arch_timer.h
>> +++ b/arch/arm/include/asm/arch_timer.h
>> @@ -95,8 +95,13 @@ static inline void 
>> arch_counter_set_user_access(void)
>>
>>  	asm volatile("mrc p15, 0, %0, c14, c1, 0" : "=r" (cntkctl));
>>
>> -	/* disable user access to everything */
>> -	cntkctl &= ~((3 << 8) | (7 << 0));
>> +	/* Disable user access to both physical/virtual counters/timers. 
>> */
>> +	/* Also disable virtual event stream */
>> +	cntkctl &= ~(ARCH_TIMER_USR_PT_ACCESS_EN
>> +			| ARCH_TIMER_USR_VT_ACCESS_EN
>> +			| ARCH_TIMER_VIRT_EVT_EN
>> +			| ARCH_TIMER_USR_VCT_ACCESS_EN
>> +			| ARCH_TIMER_USR_PCT_ACCESS_EN);
>>
>>  	asm volatile("mcr p15, 0, %0, c14, c1, 0" : : "r" (cntkctl));
>>  }
>> diff --git a/arch/arm64/include/asm/arch_timer.h 
>> b/arch/arm64/include/asm/arch_timer.h
>> index 98abd47..00b09d0 100644
>> --- a/arch/arm64/include/asm/arch_timer.h
>> +++ b/arch/arm64/include/asm/arch_timer.h
>> @@ -101,12 +101,16 @@ static inline void 
>> arch_counter_set_user_access(void)
>>  {
>>  	u32 cntkctl;
>>
>> -	/* Disable user access to the timers and the physical counter. */
>>  	asm volatile("mrs	%0, cntkctl_el1" : "=r" (cntkctl));
>> -	cntkctl &= ~((3 << 8) | (1 << 0));
>>
>> -	/* Enable user access to the virtual counter and frequency. */
>> -	cntkctl |= (1 << 1);
>> +	/* Disable user access to the timers and the physical counter. */
>> +	cntkctl &= ~(ARCH_TIMER_USR_PT_ACCESS_EN
>> +			| ARCH_TIMER_USR_VT_ACCESS_EN
>> +			| ARCH_TIMER_USR_PCT_ACCESS_EN);
>> +
>> +	/* Enable user access to the virtual counter. */
>> +	cntkctl |= ARCH_TIMER_USR_VCT_ACCESS_EN;
>> +
>>  	asm volatile("msr	cntkctl_el1, %0" : : "r" (cntkctl));
>>  }
>
> Before doing those changes, I suggest you kill 
> include/asm/arch_timer.h
> header file and move the functions directly in the arm_arch_timer.c 
> as
> they are only used by it.

How do you suggest to proceed? Having #ifdefs in arm_arch_timer.c to 
cope with the inline assembly functions present in both arm and arm64 
include files? Doesn't seem much of a progress to me...

>> diff --git a/include/clocksource/arm_arch_timer.h 
>> b/include/clocksource/arm_arch_timer.h
>> index c463ce9..551f7e9 100644
>> --- a/include/clocksource/arm_arch_timer.h
>> +++ b/include/clocksource/arm_arch_timer.h
>> @@ -29,6 +29,14 @@
>>  #define ARCH_TIMER_PHYS_ACCESS		0
>>  #define ARCH_TIMER_VIRT_ACCESS		1
>>
>> +#define ARCH_TIMER_USR_PCT_ACCESS_EN	(1 << 0) /* physical counter 
>> */
>> +#define ARCH_TIMER_USR_VCT_ACCESS_EN	(1 << 1) /* virtual counter */
>> +#define ARCH_TIMER_VIRT_EVT_EN		(1 << 2)
>> +#define ARCH_TIMER_EVT_TRIGGER_SHIFT	(4)
>> +#define ARCH_TIMER_EVT_TRIGGER_MASK	(0xF << 
>> ARCH_TIMER_EVT_TRIGGER_SHIFT)
>> +#define ARCH_TIMER_USR_VT_ACCESS_EN	(1 << 8) /* virtual timer 
>> registers */
>> +#define ARCH_TIMER_USR_PT_ACCESS_EN	(1 << 9) /* physical timer 
>> registers */
>> +
>>  #ifdef CONFIG_ARM_ARCH_TIMER
>>
>>  extern u32 arch_timer_get_rate(void);
>>

         M.
-- 
Fast, cheap, reliable. Pick two.
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