Re: [PATCH v5 15/20] watchdog: s3c2410_wdt: Add support for WTCON register DBGACK_MASK bit

[William McVicker <willmcvicker@google.com>]

On 12/01/2023, Peter Griffin wrote:
> The WDT uses the CPU core signal DBGACK to determine whether the SoC
> is running in debug mode or not. If the DBGACK signal is asserted and
> DBGACK_MASK bit is enabled, then WDT output and interrupt is masked
> (disabled).
> 
> Presence of the DBGACK_MASK bit is determined by adding a new
> QUIRK_HAS_DBGACK_BIT quirk.
> 
> Signed-off-by: Peter Griffin <peter.griffin@linaro.org>

Tested-by: Will McVicker <willmcvicker@google.com>

---

I verified boot to a busybox console and that the watchdog probes.

Regards,
Will

> ---
>  drivers/watchdog/s3c2410_wdt.c | 27 ++++++++++++++++++++++++---
>  1 file changed, 24 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c
> index 0b4bd883ff28..39f3489e41d6 100644
> --- a/drivers/watchdog/s3c2410_wdt.c
> +++ b/drivers/watchdog/s3c2410_wdt.c
> @@ -34,9 +34,10 @@
>  
>  #define S3C2410_WTCNT_MAXCNT	0xffff
>  
> -#define S3C2410_WTCON_RSTEN	(1 << 0)
> -#define S3C2410_WTCON_INTEN	(1 << 2)
> -#define S3C2410_WTCON_ENABLE	(1 << 5)
> +#define S3C2410_WTCON_RSTEN		(1 << 0)
> +#define S3C2410_WTCON_INTEN		(1 << 2)
> +#define S3C2410_WTCON_ENABLE		(1 << 5)
> +#define S3C2410_WTCON_DBGACK_MASK	(1 << 16)
>  
>  #define S3C2410_WTCON_DIV16	(0 << 3)
>  #define S3C2410_WTCON_DIV32	(1 << 3)
> @@ -100,12 +101,17 @@
>   * %QUIRK_HAS_PMU_CNT_EN: PMU block has some register (e.g. CLUSTERx_NONCPU_OUT)
>   * with "watchdog counter enable" bit. That bit should be set to make watchdog
>   * counter running.
> + *
> + * %QUIRK_HAS_DBGACK_BIT: WTCON register has DBGACK_MASK bit. Setting the
> + * DBGACK_MASK bit disables the watchdog outputs when the SoC is in debug mode.
> + * Debug mode is determined by the DBGACK CPU signal.
>   */
>  #define QUIRK_HAS_WTCLRINT_REG			(1 << 0)
>  #define QUIRK_HAS_PMU_MASK_RESET		(1 << 1)
>  #define QUIRK_HAS_PMU_RST_STAT			(1 << 2)
>  #define QUIRK_HAS_PMU_AUTO_DISABLE		(1 << 3)
>  #define QUIRK_HAS_PMU_CNT_EN			(1 << 4)
> +#define QUIRK_HAS_DBGACK_BIT			(1 << 5)
>  
>  /* These quirks require that we have a PMU register map */
>  #define QUIRKS_HAVE_PMUREG \
> @@ -375,6 +381,19 @@ static int s3c2410wdt_enable(struct s3c2410_wdt *wdt, bool en)
>  	return 0;
>  }
>  
> +static void s3c2410wdt_mask_dbgack(struct s3c2410_wdt *wdt)
> +{
> +	unsigned long wtcon;
> +
> +	if (!(wdt->drv_data->quirks & QUIRK_HAS_DBGACK_BIT))
> +		return;
> +
> +	/*  disable watchdog outputs if CPU is in debug mode */
> +	wtcon = readl(wdt->reg_base + S3C2410_WTCON);
> +	wtcon |= S3C2410_WTCON_DBGACK_MASK;
> +	writel(wtcon, wdt->reg_base + S3C2410_WTCON);
> +}
> +
>  static int s3c2410wdt_keepalive(struct watchdog_device *wdd)
>  {
>  	struct s3c2410_wdt *wdt = watchdog_get_drvdata(wdd);
> @@ -700,6 +719,8 @@ static int s3c2410wdt_probe(struct platform_device *pdev)
>  	wdt->wdt_device.bootstatus = s3c2410wdt_get_bootstatus(wdt);
>  	wdt->wdt_device.parent = dev;
>  
> +	s3c2410wdt_mask_dbgack(wdt);
> +
>  	/*
>  	 * If "tmr_atboot" param is non-zero, start the watchdog right now. Also
>  	 * set WDOG_HW_RUNNING bit, so that watchdog core can kick the watchdog.
> -- 
> 2.43.0.rc2.451.g8631bc7472-goog
>