Re: [PATCH 2/2] watchdog: aspeed: Allow configuring for alternate boot

[Eddie James]

On 03/09/2018 04:06 PM, Guenter Roeck wrote:
> On Fri, Mar 09, 2018 at 03:58:20PM -0600, Eddie James wrote:
> > From: Milton Miller <miltonm@xxxxxxxxxx>
> >
> > Allow the device tree to specify a watchdog to fallover to
> > the alternate boot source.
> >
> > The aspeeed watchdog can set a latch directing flash chip select 0 to
> > chip select 1, allowing boot from an alternate media if the watchdog
> > is not reset in time.  On the ast2400 bank 1 also goes to flash bank 1,
> > while on the ast2500 the chip selects are swapped.
> >
> > Signed-off-by: Milton Miller <miltonm@xxxxxxxxxx>
> > Signed-off-by: Eddie James <eajames@xxxxxxxxxxxxxxxxxx>
> This is already documented in the bindings document, so the property
> should be ok.
>
> Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>

Thanks. On a related note, our system has need of a way to determine if 
it's currently booted from the alternate chip or not. It seems the only 
way to tell is to look at the ast2400/2500 watchdog timeout status 
register. We can add some debugfs to the aspeed driver I guess, but I 
wonder if this is a common enough situation that the watchdog core could 
use some debugfs or sysfs for providing that info?

Thanks,
Eddie

> > ---
> >   drivers/watchdog/aspeed_wdt.c | 3 +++
> >   1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c
> > index d1987d6..f41d246 100644
> > --- a/drivers/watchdog/aspeed_wdt.c
> > +++ b/drivers/watchdog/aspeed_wdt.c
> > @@ -46,6 +46,7 @@ struct aspeed_wdt_config {
> >   #define WDT_RELOAD_VALUE	0x04
> >   #define WDT_RESTART		0x08
> >   #define WDT_CTRL		0x0C
> > +#define   WDT_CTRL_BOOT_SECONDARY	BIT(7)
> >   #define   WDT_CTRL_RESET_MODE_SOC	(0x00 << 5)
> >   #define   WDT_CTRL_RESET_MODE_FULL_CHIP	(0x01 << 5)
> >   #define   WDT_CTRL_RESET_MODE_ARM_CPU	(0x10 << 5)
> > @@ -245,6 +246,8 @@ static int aspeed_wdt_probe(struct platform_device *pdev)
> >   	}
> >   	if (of_property_read_bool(np, "aspeed,external-signal"))
> >   		wdt->ctrl |= WDT_CTRL_WDT_EXT;
> > +	if (of_property_read_bool(np, "aspeed,alt-boot"))
> > +		wdt->ctrl |= WDT_CTRL_BOOT_SECONDARY;
> >   
> >   	if (readl(wdt->base + WDT_CTRL) & WDT_CTRL_ENABLE)  {
> >   		/*
> > --
> > 1.8.3.1