linux-kernel - Re: [PATCH v3 10/10] clocksource: import ARC timer driver

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Message-ID: <20161110104901.GA18678@mai>
Date:   Thu, 10 Nov 2016 11:49:01 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Vineet Gupta <Vineet.Gupta1@...opsys.com>
Cc:     Noam Camus <noamca@...lanox.com>, tglx@...utronix.de,
        linux-snps-arc@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Alexey.Brodkin@...opsys.com
Subject: Re: [PATCH v3 10/10] clocksource: import ARC timer driver

On Thu, Nov 03, 2016 at 04:33:35PM -0700, Vineet Gupta wrote:
> This adds support for
> 
>  - CONFIG_ARC_TIMERS : legacy 32-bit TIMER0 and TIMER1 which count UP
>    from @CNT to @LIMIT, before optionally triggering an interrupt.
>    These are programmed using ARC auxiliary register interface.
>    These are present in all ARC cores (ARC700 and ARC HS38)
>    TIMER0 serves as clockevent for all ARC linux builds.
>    TIMER1 is used for clocksource in arc700 builds.
> 
>  - CONFIG_ARC_TIMERS_64BIT: 64-bit counters, RTC and GFRC found in
>    ARC HS38 cores. These are independnet IP blocks with different
>    programming model respectively.
> 
> Signed-off-by: Vineet Gupta <vgupta@...opsys.com>
> ---

[ ... ]

>  config ARC
>  	def_bool y
> +	select ARC_TIMERS
>  	select ARCH_SUPPORTS_ATOMIC_RMW if ARC_HAS_LLSC
>  	select BUILDTIME_EXTABLE_SORT
> -	select CLKSRC_OF
>  	select CLONE_BACKWARDS
>  	select COMMON_CLK
>  	select GENERIC_ATOMIC64 if !ISA_ARCV2 || !(ARC_HAS_LL64 && ARC_HAS_LLSC)
> @@ -115,6 +115,7 @@ config ISA_ARCOMPACT
>  
>  config ISA_ARCV2
>  	bool "ARC ISA v2"
> +	select ARC_TIMERS_64BIT
>  	help
>  	  ISA for the Next Generation ARC-HS cores
>  
> @@ -410,10 +411,6 @@ config ARC_HAS_DIV_REM
>  	bool "Insn: div, divu, rem, remu"
>  	default y
>  
> -config ARC_TIMERS_64BIT
> -	bool "64-bit r/o cycle counters RTC (up) and GFRC (smp)"
> -	default y
> -
>  config ARC_NUMBER_OF_INTERRUPTS
>  	int "Number of interrupts"
>  	range 8 240
> diff --git a/arch/arc/kernel/Makefile b/arch/arc/kernel/Makefile
> index cfcdedf52ff8..8942c5c3b4c5 100644
> --- a/arch/arc/kernel/Makefile
> +++ b/arch/arc/kernel/Makefile
> @@ -8,7 +8,7 @@
>  # Pass UTS_MACHINE for user_regset definition
>  CFLAGS_ptrace.o		+= -DUTS_MACHINE='"$(UTS_MACHINE)"'
>  
> -obj-y	:= arcksyms.o setup.o irq.o time.o reset.o ptrace.o process.o devtree.o
> +obj-y	:= arcksyms.o setup.o irq.o reset.o ptrace.o process.o devtree.o
>  obj-y	+= signal.o traps.o sys.o troubleshoot.o stacktrace.o disasm.o
>  obj-$(CONFIG_ISA_ARCOMPACT)		+= entry-compact.o intc-compact.o
>  obj-$(CONFIG_ISA_ARCV2)			+= entry-arcv2.o intc-arcv2.o
> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> index e2c6e43cf8ca..a53bd50164e7 100644
> --- a/drivers/clocksource/Kconfig
> +++ b/drivers/clocksource/Kconfig
> @@ -282,6 +282,25 @@ config CLKSRC_MPS2
>  	select CLKSRC_MMIO
>  	select CLKSRC_OF
>  
> +config ARC_TIMERS
> +	bool "Support for 32-bit TIMERn counters in ARC Cores" if COMPILE_TEST
> +	depends on GENERIC_CLOCKEVENTS
> +	select CLKSRC_OF
> +	help
> +	  These are legacy 32-bit TIMER0 and TIMER1 counters found on all ARC cores
> +	  (ARC700 as well as ARC HS38).
> +	  TIMER0 serves as clockevent while TIMER1 provides clocksource
> +
> +config ARC_TIMERS_64BIT
> +	bool "Support for 64-bit counters in ARC HS38 cores" if COMPILE_TEST
> +	depends on GENERIC_CLOCKEVENTS
> +	select CLKSRC_OF
> +	help
> +	  This enables 2 different 64-bit timers: RTC (for UP) and GFRC (for SMP)
> +	  RTC is implemented inside the core, while GFRC sits outside the core in
> +	  ARConnect IP block. Driver automatically picks one of them for clocksource
> +	  as appropriate.
> +
>  config ARM_ARCH_TIMER
>  	bool
>  	select CLKSRC_OF if OF
> diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
> index cf87f407f1ad..a14111e1f087 100644
> --- a/drivers/clocksource/Makefile
> +++ b/drivers/clocksource/Makefile
> @@ -51,6 +51,7 @@ obj-$(CONFIG_CLKSRC_TI_32K)	+= timer-ti-32k.o
>  obj-$(CONFIG_CLKSRC_NPS)	+= timer-nps.o
>  obj-$(CONFIG_OXNAS_RPS_TIMER)	+= timer-oxnas-rps.o
>  
> +obj-$(CONFIG_ARC_TIMERS)		+= arc_timer.o

I don't see arc_timer.o compiled if ARC_TIMERS_64BIT only is set.

Wouldn't make sense to fold ARC_TIMERS and ARC_TIMERS_64BIT ?