linux-kernel - Re: [PATCH v2] watchdog: aspeed: Allow configuring for alternate boot

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Date:   Thu, 15 Mar 2018 22:27:58 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Eddie James <eajames@...ux.vnet.ibm.com>,
        linux-watchdog@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, joel@....id.au,
        wim@...ux-watchdog.org, Milton Miller <miltonm@...ibm.com>
Subject: Re: [PATCH v2] watchdog: aspeed: Allow configuring for alternate boot

On 03/15/2018 09:02 AM, Eddie James wrote:
> From: Milton Miller <miltonm@...ibm.com>
> 
> 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.
> 
> Also clear the secondary boot bit during the machine restart operation.
> Otherwise, the system will switch to the alternate boot after every
> reboot, which is not desired.
> 
> Signed-off-by: Milton Miller <miltonm@...ibm.com>
> Signed-off-by: Eddie James <eajames@...ux.vnet.ibm.com>

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

> ---
> Changes since v1:
>   * Disable secondary boot before the restart operation.
> 
>   drivers/watchdog/aspeed_wdt.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/watchdog/aspeed_wdt.c b/drivers/watchdog/aspeed_wdt.c
> index d1987d6..a5b8eb2 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)
> @@ -158,6 +159,7 @@ static int aspeed_wdt_restart(struct watchdog_device *wdd,
>   {
>   	struct aspeed_wdt *wdt = to_aspeed_wdt(wdd);
>   
> +	wdt->ctrl &= ~WDT_CTRL_BOOT_SECONDARY;
>   	aspeed_wdt_enable(wdt, 128 * WDT_RATE_1MHZ / 1000);
>   
>   	mdelay(1000);
> @@ -245,6 +247,8 @@ 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)  {
>   		/*
>