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 10:50:23 +0200
From:	Daniel Lezcano <daniel.lezcano@...aro.org>
To:	Sudeep KarkadaNagesha <Sudeep.KarkadaNagesha@....com>
CC:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v3 1/6] ARM/ARM64: arch_timer: add macros for bits in
 control register

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.

> 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);
> 


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