linux-kernel - Re: [RFC PATCH 07/13] m68k: amiga: Convert to clocksource API

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Message-ID: <CAMuHMdU15gaEcwG4JCFxDwsA-dm0uHzZe_EmtoSLgOV2XAgWbQ@mail.gmail.com>
Date:   Mon, 12 Nov 2018 10:02:02 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Finn Thain <fthain@...egraphics.com.au>
Cc:     Arnd Bergmann <arnd@...db.de>,
        Stephen N Chivers <schivers@....com.au>,
        Thomas Gleixner <tglx@...utronix.de>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        John Stultz <john.stultz@...aro.org>,
        linux-m68k <linux-m68k@...ts.linux-m68k.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 07/13] m68k: amiga: Convert to clocksource API

Hi Finn,

On Mon, Nov 12, 2018 at 5:46 AM Finn Thain <fthain@...egraphics.com.au> wrote:
> Add a platform clocksource by adapting the existing arch_gettimeoffset
> implementation.
>
> Signed-off-by: Finn Thain <fthain@...egraphics.com.au>

Thanks for your patch!

> --- a/arch/m68k/amiga/config.c
> +++ b/arch/m68k/amiga/config.c
> @@ -17,6 +17,7 @@
>  #include <linux/mm.h>
>  #include <linux/seq_file.h>
>  #include <linux/tty.h>
> +#include <linux/clocksource.h>
>  #include <linux/console.h>
>  #include <linux/rtc.h>
>  #include <linux/init.h>
> @@ -461,7 +462,30 @@ void __init config_amiga(void)
>                 *(unsigned char *)ZTWO_VADDR(0xde0002) |= 0x80;
>  }
>
> +static u64 amiga_read_clk(struct clocksource *cs);
> +
> +static struct clocksource amiga_clk = {
> +       .name   = "ciab",
> +       .rating = 250,
> +       .read   = amiga_read_clk,
> +       .mask   = CLOCKSOURCE_MASK(32),
> +       .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
> +};
> +
>  static unsigned short jiffy_ticks;
> +static u32 clk_total;

Shouldn't clk_total be u64?

> +
> +static irqreturn_t ciab_timer_handler(int irq, void *data)
> +{
> +       irq_handler_t timer_routine = data;
> +       unsigned long flags;
> +
> +       local_irq_save(flags);
> +       clk_total += jiffy_ticks;
> +       local_irq_restore(flags);
> +
> +       return timer_routine(irq, data);
> +}

[...]

> -static u32 amiga_gettimeoffset(void)
> +static u64 amiga_read_clk(struct clocksource *cs)
>  {
>         unsigned long flags;
>         unsigned short hi, lo, hi2;
> @@ -512,14 +537,13 @@ static u32 amiga_gettimeoffset(void)
>         if (ticks > jiffy_ticks / 2)
>                 /* check for pending interrupt */
>                 if (cia_set_irq(&ciab_base, 0) & CIA_ICR_TA)
> -                       offset = 10000;
> +                       offset = jiffy_ticks;
>
>         local_irq_restore(flags);
>
>         ticks = jiffy_ticks - ticks;
> -       ticks = (10000 * ticks) / jiffy_ticks;
>
> -       return (ticks + offset) * 1000;
> +       return clk_total + ticks + offset;

... to return a full 64-bit value here?

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds