linux-kernel - RE: [PATCH 2/2] watchdog: rzg2l_wdt: Handle TYPE-B reset for RZ/V2M

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Message-ID: <TYWPR01MB87756C88E5F099C02D3F5CA6C2C19@TYWPR01MB8775.jpnprd01.prod.outlook.com>
Date:   Mon, 16 Jan 2023 15:29:27 +0000
From:   Fabrizio Castro <fabrizio.castro.jz@...esas.com>
To:     Guenter Roeck <linux@...ck-us.net>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Geert Uytterhoeven <geert+renesas@...der.be>
CC:     Biju Das <biju.das.jz@...renesas.com>,
        "linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Chris Paterson <Chris.Paterson2@...esas.com>,
        Biju Das <biju.das@...renesas.com>,
        "linux-renesas-soc@...r.kernel.org" 
        <linux-renesas-soc@...r.kernel.org>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Jacopo Mondi <jacopo@...ndi.org>
Subject: RE: [PATCH 2/2] watchdog: rzg2l_wdt: Handle TYPE-B reset for RZ/V2M

Hi Geert,

Have you had the chance to look into this patch?
I was hoping it could get taken for v6.3?

Thanks,
Fab

> 
> On 11/17/22 03:49, Fabrizio Castro wrote:
> > As per section 48.4 of the HW User Manual, IPs in the RZ/V2M
> > SoC need either a TYPE-A reset sequence or a TYPE-B reset
> > sequence. More specifically, the watchdog IP needs a TYPE-B
> > reset sequence.
> >
> > If the proper reset sequence isn't implemented, then resetting
> > IPs may lead to undesired behaviour. In the restart callback of
> > the watchdog driver the reset has basically no effect on the
> > desired funcionality, as the register writes following the reset
> > happen before the IP manages to come out of reset.
> >
> > Implement the TYPE-B reset sequence in the watchdog driver to
> > address the issues with the restart callback on RZ/V2M.
> >
> > Fixes: ec122fd94eeb ("watchdog: rzg2l_wdt: Add rzv2m support")
> > Signed-off-by: Fabrizio Castro <fabrizio.castro.jz@...esas.com>
> 
> Reviewed-by: Guenter Roeck <linux@...ck-us.net>
> 
> > ---
> >   drivers/watchdog/rzg2l_wdt.c | 37 +++++++++++++++++++++++++++++++++++-
> >   1 file changed, 36 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/watchdog/rzg2l_wdt.c b/drivers/watchdog/rzg2l_wdt.c
> > index ceca42db0837..d404953d0e0f 100644
> > --- a/drivers/watchdog/rzg2l_wdt.c
> > +++ b/drivers/watchdog/rzg2l_wdt.c
> > @@ -8,6 +8,7 @@
> >   #include <linux/clk.h>
> >   #include <linux/delay.h>
> >   #include <linux/io.h>
> > +#include <linux/iopoll.h>
> >   #include <linux/kernel.h>
> >   #include <linux/module.h>
> >   #include <linux/of_device.h>
> > @@ -35,6 +36,8 @@
> >
> >   #define F2CYCLE_NSEC(f)			(1000000000 / (f))
> >
> > +#define RZV2M_A_NSEC			730
> > +
> >   static bool nowayout = WATCHDOG_NOWAYOUT;
> >   module_param(nowayout, bool, 0);
> >   MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started
> (default="
> > @@ -51,11 +54,35 @@ struct rzg2l_wdt_priv {
> >   	struct reset_control *rstc;
> >   	unsigned long osc_clk_rate;
> >   	unsigned long delay;
> > +	unsigned long minimum_assertion_period;
> >   	struct clk *pclk;
> >   	struct clk *osc_clk;
> >   	enum rz_wdt_type devtype;
> >   };
> >
> > +static int rzg2l_wdt_reset(struct rzg2l_wdt_priv *priv)
> > +{
> > +	int err, status;
> > +
> > +	if (priv->devtype == WDT_RZV2M) {
> > +		/* WDT needs TYPE-B reset control */
> > +		err = reset_control_assert(priv->rstc);
> > +		if (err)
> > +			return err;
> > +		ndelay(priv->minimum_assertion_period);
> > +		err = reset_control_deassert(priv->rstc);
> > +		if (err)
> > +			return err;
> > +		err = read_poll_timeout(reset_control_status, status,
> > +					status != 1, 0, 1000, false,
> > +					priv->rstc);
> > +	} else {
> > +		err = reset_control_reset(priv->rstc);
> > +	}
> > +
> > +	return err;
> > +}
> > +
> >   static void rzg2l_wdt_wait_delay(struct rzg2l_wdt_priv *priv)
> >   {
> >   	/* delay timer when change the setting register */
> > @@ -115,7 +142,7 @@ static int rzg2l_wdt_stop(struct watchdog_device
> *wdev)
> >   {
> >   	struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev);
> >
> > -	reset_control_reset(priv->rstc);
> > +	rzg2l_wdt_reset(priv);
> >   	pm_runtime_put(wdev->parent);
> >
> >   	return 0;
> > @@ -154,6 +181,7 @@ static int rzg2l_wdt_restart(struct watchdog_device
> *wdev,
> >   		rzg2l_wdt_write(priv, PEEN_FORCE, PEEN);
> >   	} else {
> >   		/* RZ/V2M doesn't have parity error registers */
> > +		rzg2l_wdt_reset(priv);
> >
> >   		wdev->timeout = 0;
> >
> > @@ -251,6 +279,13 @@ static int rzg2l_wdt_probe(struct platform_device
> *pdev)
> >
> >   	priv->devtype = (uintptr_t)of_device_get_match_data(dev);
> >
> > +	if (priv->devtype == WDT_RZV2M) {
> > +		priv->minimum_assertion_period = RZV2M_A_NSEC +
> > +			3 * F2CYCLE_NSEC(pclk_rate) + 5 *
> > +			max(F2CYCLE_NSEC(priv->osc_clk_rate),
> > +			    F2CYCLE_NSEC(pclk_rate));
> > +	}
> > +
> >   	pm_runtime_enable(&pdev->dev);
> >
> >   	priv->wdev.info = &rzg2l_wdt_ident;