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

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Date:   Fri, 1 Feb 2019 22:39:46 +0800
From:   Joseph Lo <josephl@...dia.com>
To:     Jon Hunter <jonathanh@...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 2/1/19 8:44 PM, Jon Hunter wrote:
> 
> 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.
Okay, will do.
> 
> Furthermore, a lot of these TIMERx_BASE definitions are unused AFAICT.
> Would be good to get rid of these.

Okay.
> 
> 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)
> 
This can't get the timer base address. I think you mean ...

+#ifdef CONFIG_ARM
+#define TIMER_CPU0 0x50 /* TIMER3 */
+#else
+#define TIMER_CPU0 0x90 /* TIMER10 */
+#endif
+#define TIMER_BASE_FOR_CPU(cpu) (TIMER_CPU0 + (cpu) * 8)

This doesn't need.
+#define TIMER_FOR_CPU(cpu) (TIMER_CPU0 + cpu)

Will fix above accordingly and adding your ack tag.

Thanks,
Joseph

> Otherwise looks good to me.
> 
> Cheers
> Jon
>