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Sender: Guenter Roeck <groeck7@gmail.com>
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Date: Tue, 23 Jan 2024 02:33:36 -0800
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Subject: Re: [PATCH 3/9] watchdog: s3c2410_wdt: update to use new
 exynos_pmu_*() apis
Content-Language: en-US
To: Peter Griffin <peter.griffin@linaro.org>, arnd@arndb.de,
 robh+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org,
 wim@linux-watchdog.org, conor+dt@kernel.org, alim.akhtar@samsung.com,
 jaewon02.kim@samsung.com, chanho61.park@samsung.com,
 semen.protsenko@linaro.org
Cc: kernel-team@android.com, tudor.ambarus@linaro.org,
 andre.draszik@linaro.org, saravanak@google.com, willmcvicker@google.com,
 linux-fsd@tesla.com, 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: <20240122225710.1952066-1-peter.griffin@linaro.org>
 <20240122225710.1952066-4-peter.griffin@linaro.org>
From: Guenter Roeck <linux@roeck-us.net>
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In-Reply-To: <20240122225710.1952066-4-peter.griffin@linaro.org>
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On 1/22/24 14:57, Peter Griffin wrote:
> Instead of obtaining the PMU regmap directly use the new exynos_pmu_*()
> APIs. The exynos_pmu_ APIs allow support of newer Exynos SoCs that have
> atomic set/clear bit hardware and platforms where the PMU registers can
> only be accessed via SMC call.
> 

Not really sure about using a direect API instead of regmap. I personally
think that regmap is more generic and like the idea of abstracting hardware
accesses this way. Since that is POV, I won't argue about it. However,

> As all platforms that have PMU registers use these new APIs, remove the
> syscon regmap lookup code, as it is now redundant.
>

if syscon is now no longer needed, why keep selecting MFD_SYSCON below,
and why are linux/mfd/syscon.h and linux/regmap.h still included ?

Also, the driver did not previously only support ARCH_EXYNOS but also
ARCH_S3C64XX and ARCH_S5PV210. It is not entirely (actually, not at all)
clear to me if and how those platforms are now supported. EXYNOS_PMU
still seems to depend on ARCH_EXYNOS. How can the driver select
EXYNOS_PMU if ARCH_EXYNOS=n ?

Also, ARCH_EXYNOS already selects EXYNOS_PMU, so a conditional
"select EXYNOS_PMU if ARCH_EXYNOS" would not make sense (or be required)
either.

Please explain all the above.

Thanks,
Guenter

> Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
> ---
>   drivers/watchdog/Kconfig       |  1 +
>   drivers/watchdog/s3c2410_wdt.c | 25 +++++++++----------------
>   2 files changed, 10 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 7d22051b15a2..b3e90e1ddf14 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -513,6 +513,7 @@ config S3C2410_WATCHDOG
>   	depends on ARCH_S3C64XX || ARCH_S5PV210 || ARCH_EXYNOS || COMPILE_TEST
>   	select WATCHDOG_CORE
>   	select MFD_SYSCON if ARCH_EXYNOS
> +	select EXYNOS_PMU
>   	help
>   	  Watchdog timer block in the Samsung S3C64xx, S5Pv210 and Exynos
>   	  SoCs. This will reboot the system when the timer expires with
> diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c
> index 349d30462c8c..fd3a9ce870a0 100644
> --- a/drivers/watchdog/s3c2410_wdt.c
> +++ b/drivers/watchdog/s3c2410_wdt.c
> @@ -28,6 +28,8 @@
>   #include <linux/regmap.h>
>   #include <linux/delay.h>
>   
> +#include <linux/soc/samsung/exynos-pmu.h>
> +
>   #define S3C2410_WTCON		0x00
>   #define S3C2410_WTDAT		0x04
>   #define S3C2410_WTCNT		0x08
> @@ -187,7 +189,6 @@ struct s3c2410_wdt {
>   	struct watchdog_device	wdt_device;
>   	struct notifier_block	freq_transition;
>   	const struct s3c2410_wdt_variant *drv_data;
> -	struct regmap *pmureg;
>   };
>   
>   static const struct s3c2410_wdt_variant drv_data_s3c2410 = {
> @@ -355,8 +356,8 @@ static int s3c2410wdt_disable_wdt_reset(struct s3c2410_wdt *wdt, bool mask)
>   	const u32 val = mask ? mask_val : 0;
>   	int ret;
>   
> -	ret = regmap_update_bits(wdt->pmureg, wdt->drv_data->disable_reg,
> -				 mask_val, val);
> +	ret = exynos_pmu_update(wdt->drv_data->disable_reg,
> +				mask_val, val);
>   	if (ret < 0)
>   		dev_err(wdt->dev, "failed to update reg(%d)\n", ret);
>   
> @@ -370,8 +371,8 @@ static int s3c2410wdt_mask_wdt_reset(struct s3c2410_wdt *wdt, bool mask)
>   	const u32 val = (mask ^ val_inv) ? mask_val : 0;
>   	int ret;
>   
> -	ret = regmap_update_bits(wdt->pmureg, wdt->drv_data->mask_reset_reg,
> -				 mask_val, val);
> +	ret = exynos_pmu_update(wdt->drv_data->mask_reset_reg,
> +				mask_val, val);
>   	if (ret < 0)
>   		dev_err(wdt->dev, "failed to update reg(%d)\n", ret);
>   
> @@ -384,8 +385,8 @@ static int s3c2410wdt_enable_counter(struct s3c2410_wdt *wdt, bool en)
>   	const u32 val = en ? mask_val : 0;
>   	int ret;
>   
> -	ret = regmap_update_bits(wdt->pmureg, wdt->drv_data->cnt_en_reg,
> -				 mask_val, val);
> +	ret = exynos_pmu_update(wdt->drv_data->cnt_en_reg,
> +				mask_val, val);
>   	if (ret < 0)
>   		dev_err(wdt->dev, "failed to update reg(%d)\n", ret);
>   
> @@ -617,7 +618,7 @@ static inline unsigned int s3c2410wdt_get_bootstatus(struct s3c2410_wdt *wdt)
>   	if (!(wdt->drv_data->quirks & QUIRK_HAS_PMU_RST_STAT))
>   		return 0;
>   
> -	ret = regmap_read(wdt->pmureg, wdt->drv_data->rst_stat_reg, &rst_stat);
> +	ret = exynos_pmu_read(wdt->drv_data->rst_stat_reg, &rst_stat);
>   	if (ret)
>   		dev_warn(wdt->dev, "Couldn't get RST_STAT register\n");
>   	else if (rst_stat & BIT(wdt->drv_data->rst_stat_bit))
> @@ -698,14 +699,6 @@ static int s3c2410wdt_probe(struct platform_device *pdev)
>   	if (ret)
>   		return ret;
>   
> -	if (wdt->drv_data->quirks & QUIRKS_HAVE_PMUREG) {
> -		wdt->pmureg = syscon_regmap_lookup_by_phandle(dev->of_node,
> -						"samsung,syscon-phandle");
> -		if (IS_ERR(wdt->pmureg))
> -			return dev_err_probe(dev, PTR_ERR(wdt->pmureg),
> -					     "syscon regmap lookup failed.\n");
> -	}
> -
>   	wdt_irq = platform_get_irq(pdev, 0);
>   	if (wdt_irq < 0)
>   		return wdt_irq;