Re: [PATCH v2 03/15] watchdog: orion: Use atomic access for shared registers

[Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>]

On Tuesday 21 January 2014 06:12:29 Ezequiel Garcia wrote:
>         writel(~WDT_INT_REQ, BRIDGE_CAUSE);
>  
>         /* Enable watchdog timer */
> -       reg = readl(wdt_reg + TIMER_CTRL);
> -       reg |= WDT_EN;
> -       writel(reg, wdt_reg + TIMER_CTRL);
> +       atomic_io_modify(wdt_reg + TIMER_CTRL, WDT_EN, WDT_EN);

As mentioned in my comment for patch 2, it seems that the exported
orion_timer_ctrl_clrset() function would be more appropriate for this.

>         /* Enable reset on watchdog */
> -       reg = readl(RSTOUTn_MASK);
> -       reg |= WDT_RESET_OUT_EN;
> -       writel(reg, RSTOUTn_MASK);
> +       atomic_io_modify(RSTOUTn_MASK, WDT_RESET_OUT_EN, WDT_RESET_OUT_EN);

And this register already has an abstraction in
arch/arm/mach-mvebu/system-controller.c. I would prefer to find a way
to generalize that. I can see multiple ways to do that:

* Turn the "marvell,armada-370-xp-system-controller" device into a "syscon"
  device that can be used through regmap from other parts of the kernel.

* Move arch/arm/mach-mvebu/system-controller.c into drivers/soc (we don't
  have this directory yet, but have discussed it in the past) to export
  soc-specific functions from there.

* Move all of the system-controller implementation into the wdt driver
  and require that this driver be enabled in order to do regular system
  reset. The system-controller can register itself as a reboot hook,
  so you can remove the ".restart = mvebu_restart" part from mach-mvebu.

	Arnd
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