Re: [PATCH V6 2/7] clocksource: tegra: add Tegra210 timer support

From: Jon Hunter <jonathanh@nvidia.com>
To: Joseph Lo <josephl@nvidia.com>,
	Thierry Reding <thierry.reding@gmail.com>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Thomas Gleixner <tglx@linutronix.de>
Cc: linux-tegra@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, Thierry Reding <treding@nvidia.com>
Subject: Re: [PATCH V6 2/7] clocksource: tegra: add Tegra210 timer support
Date: Fri, 1 Feb 2019 16:31:32 +0000	[thread overview]
Message-ID: <0272983e-bbff-601e-67fa-2cb9e852a68c@nvidia.com> (raw)
In-Reply-To: <20190201161654.18315-3-josephl@nvidia.com>

On 01/02/2019 16:16, 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.
> 
> Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Joseph Lo <josephl@nvidia.com>
> Acked-by: Thierry Reding <treding@nvidia.com>
> Acked-by: Jon Hunter <jonathanh@nvidia.com>
> ---
> v6:
>  * refine the timer defines
>  * add ack tag from Jon.
> 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 | 371 ++++++++++++++++++++--------
>  include/linux/cpuhotplug.h          |   1 +
>  3 files changed, 270 insertions(+), 104 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..f66edd63d7f4 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
> @@ -39,74 +42,145 @@
>  #define TIMERUS_USEC_CFG 0x14
>  #define TIMERUS_CNTR_FREEZE 0x4c
>  
> -#define TIMER1_BASE 0x0
> -#define TIMER2_BASE 0x8
> -#define TIMER3_BASE 0x50
> -#define TIMER4_BASE 0x58
> -
> -#define TIMER_PTV 0x0
> -#define TIMER_PCR 0x4
> -
> +#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_CPU0		0x50 /* TIMER3 */
> +#else
> +#define TIMER_CPU0		0x90 /* TIMER10 */
> +#define TIMER10_IRQ_IDX		10
> +#define IRQ_IDX_FOR_CPU(cpu)	(TIMER10_IRQ_IDX + cpu)
> +#endif
> +#define TIMER_BASE_FOR_CPU(cpu) (TIMER_CPU0 + (cpu) * 8)

So maybe I was not being clear, but what I meant was you replace
'IRQ_IDX_FOR_CPU(cpu)' with 'TIMER_FOR_CPU(cpu), because technically, we
just need to know the timer index being used for a given CPU to lookup
the associated interrupt. And so I was suggesting you make a generic
macro that could be used for both 32-bit and 64-bit ARM. However, given
that currently we do not need/use this for 32-bit ARM it is really a
mute point.

However, don't bother changing this now and you have included my ACK, so
we are all good.

Thanks!
Jon

-- 
nvpublic