Re: [PATCH v6 3/3] watchdog: mt7621-wdt: avoid ralink architecture dependent code

[Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>]

On 13/02/2023 21:05, Sergio Paracuellos wrote:
> MT7621 SoC has a system controller node. Watchdog need to access to reset
> status register. Ralink architecture and related driver are old and from
> the beggining they are using some architecture dependent operations for
> accessing this shared registers through 'asm/mach-ralink/ralink_regs.h'
> header file. However this is not ideal from a driver perspective which can
> just access to the system controller registers in an arch independent way
> using regmap syscon APIs. Update Kconfig accordingly to select new added
> dependencies and allow driver to be compile tested.
> 
> Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
> ---
>  drivers/watchdog/Kconfig      |  4 +++-
>  drivers/watchdog/mt7621_wdt.c | 18 +++++++++++++-----
>  2 files changed, 16 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index b64bc49c7..cf752ad64 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -1865,7 +1865,9 @@ config GXP_WATCHDOG
>  config MT7621_WDT
>  	tristate "Mediatek SoC watchdog"
>  	select WATCHDOG_CORE
> -	depends on SOC_MT7620 || SOC_MT7621
> +	select REGMAP_MMIO
> +	select MFD_SYSCON
> +	depends on SOC_MT7620 || SOC_MT7621 || COMPILE_TEST
>  	help
>  	  Hardware driver for the Mediatek/Ralink MT7621/8 SoC Watchdog Timer.
>  
> diff --git a/drivers/watchdog/mt7621_wdt.c b/drivers/watchdog/mt7621_wdt.c
> index 40fb2c9ba..22e979bdd 100644
> --- a/drivers/watchdog/mt7621_wdt.c
> +++ b/drivers/watchdog/mt7621_wdt.c
> @@ -15,8 +15,8 @@
>  #include <linux/moduleparam.h>
>  #include <linux/platform_device.h>
>  #include <linux/mod_devicetable.h>
> -
> -#include <asm/mach-ralink/ralink_regs.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/regmap.h>
>  
>  #define SYSC_RSTSTAT			0x38
>  #define WDT_RST_CAUSE			BIT(1)
> @@ -34,6 +34,7 @@
>  struct mt7621_wdt_data {
>  	void __iomem *base;
>  	struct reset_control *rst;
> +	struct regmap *sysc;
>  	struct watchdog_device wdt;
>  };
>  
> @@ -104,9 +105,12 @@ static int mt7621_wdt_stop(struct watchdog_device *w)
>  	return 0;
>  }
>  
> -static int mt7621_wdt_bootcause(void)
> +static int mt7621_wdt_bootcause(struct mt7621_wdt_data *d)
>  {
> -	if (rt_sysc_r32(SYSC_RSTSTAT) & WDT_RST_CAUSE)
> +	u32 val;
> +
> +	regmap_read(d->sysc, SYSC_RSTSTAT, &val);
> +	if (val & WDT_RST_CAUSE)
>  		return WDIOF_CARDRESET;
>  
>  	return 0;
> @@ -143,6 +147,10 @@ static int mt7621_wdt_probe(struct platform_device *pdev)
>  	if (!drvdata)
>  		return -ENOMEM;
>  
> +	drvdata->sysc = syscon_regmap_lookup_by_compatible("mediatek,mt7621-sysc");
> +	if (IS_ERR(drvdata->sysc))
> +		return PTR_ERR(drvdata->sysc);

This should be the backup/error path for original code using syscon
property. Looking up by compatible is really not portable/re-usable.

Best regards,
Krzysztof