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Sender: Guenter Roeck <groeck7@gmail.com>
Subject: Re: [PATCH 4/7] watchdog: s3c2410: Add support for WDT counter enable
To:     Sam Protsenko <semen.protsenko@linaro.org>,
        Wim Van Sebroeck <wim@linux-watchdog.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Cc:     linux-watchdog@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-samsung-soc@vger.kernel.org
References: <20211028183527.3050-1-semen.protsenko@linaro.org>
 <20211028183527.3050-5-semen.protsenko@linaro.org>
From:   Guenter Roeck <linux@roeck-us.net>
Message-ID: <e69282af-738b-e56e-026a-1e3adcec6a51@roeck-us.net>
Date:   Thu, 28 Oct 2021 17:16:13 -0700
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On 10/28/21 11:35 AM, Sam Protsenko wrote:
> On new Exynos chips (like Exynos850) WDT counter must be enabled to make
> WDT functional. It's done via CLUSTERx_NONCPU_OUT register, in
> CNT_EN_WDT bit. Add infrastructure needed to enable that counter.
> 
> Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
> ---
>   drivers/watchdog/s3c2410_wdt.c | 28 ++++++++++++++++++++++++++++
>   1 file changed, 28 insertions(+)
> 
> diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c
> index 7c163a257d3c..a5ef7171a90e 100644
> --- a/drivers/watchdog/s3c2410_wdt.c
> +++ b/drivers/watchdog/s3c2410_wdt.c
> @@ -97,12 +97,16 @@ struct s3c2410_wdt;
>    * @rst_stat_reg: Offset in pmureg for the register that has the reset status.
>    * @rst_stat_bit: Bit number in the rst_stat register indicating a watchdog
>    * reset.
> + * @cnt_en_reg: Offset in pmureg for the register that enables WDT counter.
> + * @cnt_en_bit: Bit number for "watchdog counter enable" in cnt_en register.
>    * @quirks: A bitfield of quirks.
>    * @disable_auto_reset: If set, this function will be called to disable
>    * automatic setting the WDT as a reset reason in RST_STAT on CPU reset; uses
>    * disable_reg field.
>    * @mask_reset: If set, this function will be called to mask WDT reset request;
>    * uses mask_reset_reg and mask_bit fields.
> + * @enable_counter: If set, this function will be called to enable WDT counter;
> + * uses cnt_en_reg and cnt_en_bit fields.
>    */
>   
>   struct s3c2410_wdt_variant {
> @@ -111,9 +115,12 @@ struct s3c2410_wdt_variant {
>   	int mask_bit;
>   	int rst_stat_reg;
>   	int rst_stat_bit;
> +	int cnt_en_reg;
> +	int cnt_en_bit;
>   	u32 quirks;
>   	int (*disable_auto_reset)(struct s3c2410_wdt *wdt, bool mask);
>   	int (*mask_reset)(struct s3c2410_wdt *wdt, bool mask);
> +	int (*enable_counter)(struct s3c2410_wdt *wdt, bool mask);

Unless there are different enable functions in the future,
the function is unnecessary. This can be handled as feature bit.

>   };
>   
>   struct s3c2410_wdt {
> @@ -132,6 +139,7 @@ struct s3c2410_wdt {
>   
>   static int s3c2410wdt_disable_wdt_reset(struct s3c2410_wdt *wdt, bool mask);
>   static int s3c2410wdt_mask_wdt_reset(struct s3c2410_wdt *wdt, bool mask);
> +static int s3c2410wdt_enable_counter(struct s3c2410_wdt *wdt, bool en);
>   
>   static const struct s3c2410_wdt_variant drv_data_s3c2410 = {
>   	.quirks = 0
> @@ -246,6 +254,20 @@ static int s3c2410wdt_mask_wdt_reset(struct s3c2410_wdt *wdt, bool mask)
>   	return ret;
>   }
>   
> +static int s3c2410wdt_enable_counter(struct s3c2410_wdt *wdt, bool en)
> +{
> +	const u32 mask_val = 1 << wdt->drv_data->cnt_en_bit;

BIT()

> +	const u32 val = en ? mask_val : 0;
> +	int ret;
> +
> +	ret = regmap_update_bits(wdt->pmureg, wdt->drv_data->cnt_en_reg,
> +				 mask_val, val);
> +	if (ret < 0)
> +		dev_err(wdt->dev, "failed to update reg(%d)\n", ret);
> +
> +	return ret;
> +}
> +
>   static int s3c2410wdt_enable(struct s3c2410_wdt *wdt, bool en)
>   {
>   	int ret;
> @@ -262,6 +284,12 @@ static int s3c2410wdt_enable(struct s3c2410_wdt *wdt, bool en)
>   			return ret;
>   	}
>   
> +	if (wdt->drv_data->enable_counter) {
> +		ret = wdt->drv_data->enable_counter(wdt, en);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
>   	return 0;
>   }
>   
>