linux-kernel - Re: [PATCH V5 2/7] clocksource: tegra: add Tegra210 timer support

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Message-ID: <5490ad66-7d20-7093-7025-1d0ec8da6dec@nvidia.com>
Date:   Fri, 1 Feb 2019 12:44:10 +0000
From:   Jon Hunter <jonathanh@...dia.com>
To:     Joseph Lo <josephl@...dia.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>
CC:     <linux-tegra@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, Thierry Reding <treding@...dia.com>
Subject: Re: [PATCH V5 2/7] clocksource: tegra: add Tegra210 timer support


On 01/02/2019 03:36, Joseph Lo wrote:
> Add support for the Tegra210 timer that runs at oscillator clock
> (TMR10-TMR13). We need these timers to work as clock event device and to
> replace the ARMv8 architected timer due to it can't survive across the
> power cycle of the CPU core or CPUPORESET signal. So it can't be a wake-up
> source when CPU suspends in power down state.
> 
> Also convert the original driver to use timer-of API.

It may have been nice to split this into 2 patches to make it easier to
see what is going on but not a big deal.

> Cc: Daniel Lezcano <daniel.lezcano@...aro.org>
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Joseph Lo <josephl@...dia.com>
> Acked-by: Thierry Reding <treding@...dia.com>
> ---
> v5:
>  * add ack tag from Thierry
> v4:
>  * merge timer-tegra210.c in previous version into timer-tegra20.c
> v3:
>  * use timer-of API
> v2:
>  * add error clean-up code
> ---
>  drivers/clocksource/Kconfig         |   2 +-
>  drivers/clocksource/timer-tegra20.c | 369 ++++++++++++++++++++--------
>  include/linux/cpuhotplug.h          |   1 +
>  3 files changed, 272 insertions(+), 100 deletions(-)
> 
> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> index a9e26f6a81a1..6af78534a285 100644
> --- a/drivers/clocksource/Kconfig
> +++ b/drivers/clocksource/Kconfig
> @@ -131,7 +131,7 @@ config SUN5I_HSTIMER
>  config TEGRA_TIMER
>  	bool "Tegra timer driver" if COMPILE_TEST
>  	select CLKSRC_MMIO
> -	depends on ARM
> +	select TIMER_OF
>  	help
>  	  Enables support for the Tegra driver.
>  
> diff --git a/drivers/clocksource/timer-tegra20.c b/drivers/clocksource/timer-tegra20.c
> index 4293943f4e2b..96a809341c9b 100644
> --- a/drivers/clocksource/timer-tegra20.c
> +++ b/drivers/clocksource/timer-tegra20.c
> @@ -15,21 +15,24 @@
>   *
>   */
>  
> -#include <linux/init.h>
> +#include <linux/clk.h>
> +#include <linux/clockchips.h>
> +#include <linux/cpu.h>
> +#include <linux/cpumask.h>
> +#include <linux/delay.h>
>  #include <linux/err.h>
> -#include <linux/time.h>
>  #include <linux/interrupt.h>
> -#include <linux/irq.h>
> -#include <linux/clockchips.h>
> -#include <linux/clocksource.h>
> -#include <linux/clk.h>
> -#include <linux/io.h>
>  #include <linux/of_address.h>
>  #include <linux/of_irq.h>
> -#include <linux/sched_clock.h>
> -#include <linux/delay.h>
> +#include <linux/percpu.h>
> +#include <linux/syscore_ops.h>
> +#include <linux/time.h>
> +
> +#include "timer-of.h"
>  
> +#ifdef CONFIG_ARM
>  #include <asm/mach/time.h>
> +#endif
>  
>  #define RTC_SECONDS            0x08
>  #define RTC_SHADOW_SECONDS     0x0c
> @@ -43,70 +46,147 @@
>  #define TIMER2_BASE 0x8
>  #define TIMER3_BASE 0x50
>  #define TIMER4_BASE 0x58
> -
> -#define TIMER_PTV 0x0
> -#define TIMER_PCR 0x4
> -
> +#define TIMER10_BASE 0x90
> +
> +#define TIMER_PTV		0x0
> +#define TIMER_PTV_EN		BIT(31)
> +#define TIMER_PTV_PER		BIT(30)
> +#define TIMER_PCR		0x4
> +#define TIMER_PCR_INTR_CLR	BIT(30)
> +
> +#ifdef CONFIG_ARM
> +#define TIMER_BASE TIMER3_BASE
> +#else
> +#define TIMER_BASE TIMER10_BASE
> +#endif
> +#define TIMER10_IRQ_IDX		10
> +#define TIMER_FOR_CPU(cpu) (TIMER_BASE + (cpu) * 8)
> +#define IRQ_IDX_FOR_CPU(cpu)	(TIMER10_IRQ_IDX + cpu)

TIMER10_IRQ_IDX and IRQ_IDX_FOR_CPU are only applicable to ARM64 and so
we should probably not defined for ARM to avoid any confusion.

Furthermore, a lot of these TIMERx_BASE definitions are unused AFAICT.
Would be good to get rid of these.

Maybe we could just have ...

 +#ifdef CONFIG_ARM
 +#define TIMER_CPU0 3
 +#else
 +#define TIMER_CPU0 10
 +#endif
 +#define TIMER_BASE_FOR_CPU(cpu) ((TIMER_CPU0 + cpu) * 8)
 +#define TIMER_FOR_CPU(cpu) (TIMER_CPU0 + cpu)

Otherwise looks good to me.

Cheers
Jon

-- 
nvpublic