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

[Guenter Roeck]

On 2/14/23 00:31, Krzysztof Kozlowski wrote:
> 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@xxxxxxxxx>
> > ---
> >   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.

I really disagree here.

$ git grep syscon_regmap_lookup_by_compatible | wc
     90     326    8940

I have not yet reviewed this code, but I do not accept this argument against it.

Guenter