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    SubjectRE: [PATCH 1/4] watchdog: sama5d4: fix WDDIS handling
    Date


    > -----Original Message-----
    > From: Alexandre Belloni [mailto:alexandre.belloni@free-electrons.com]
    > Sent: 2017年3月3日 1:31
    > To: Guenter Roeck <linux@roeck-us.net>
    > Cc: Wim Van Sebroeck <wim@iguana.be>; Nicolas Ferre - M43238
    > <Nicolas.Ferre@microchip.com>; Wenyou Yang - A41535
    > <Wenyou.Yang@microchip.com>; linux-watchdog@vger.kernel.org; linux-arm-
    > kernel@lists.infradead.org; linux-kernel@vger.kernel.org; Alexandre Belloni
    > <alexandre.belloni@free-electrons.com>
    > Subject: [PATCH 1/4] watchdog: sama5d4: fix WDDIS handling
    >
    > The datasheet states: "When setting the WDDIS bit, and while it is set, the fields
    > WDV and WDD must not be modified."
    >
    > Because the whole configuration is already cached inside .mr, wait for the user to
    > enable the watchdog to configure it so it is enabled and configured at the same
    > time (what the IP is actually expecting).
    >
    > When the watchdog is already enabled, it is not an issue to reconfigure it.

    Indeed, thanks.
    Acked-by: Wenyou.Yang <wenyou.yang@microchip.com>

    >
    > Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
    > ---
    > drivers/watchdog/sama5d4_wdt.c | 48 ++++++++++++++++++++++++++----------
    > ------
    > 1 file changed, 30 insertions(+), 18 deletions(-)
    >
    > diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c
    > index f709962018ac..5cee20caca78 100644
    > --- a/drivers/watchdog/sama5d4_wdt.c
    > +++ b/drivers/watchdog/sama5d4_wdt.c
    > @@ -44,6 +44,8 @@ MODULE_PARM_DESC(nowayout,
    > "Watchdog cannot be stopped once started (default="
    > __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
    >
    > +#define wdt_enabled (!(wdt->mr & AT91_WDT_WDDIS))
    > +
    > #define wdt_read(wdt, field) \
    > readl_relaxed((wdt)->reg_base + (field))
    >
    > @@ -89,7 +91,16 @@ static int sama5d4_wdt_set_timeout(struct
    > watchdog_device *wdd,
    > wdt->mr &= ~AT91_WDT_WDD;
    > wdt->mr |= AT91_WDT_SET_WDV(value);
    > wdt->mr |= AT91_WDT_SET_WDD(value);
    > - wdt_write(wdt, AT91_WDT_MR, wdt->mr);
    > +
    > + /*
    > + * WDDIS has to be 0 when updating WDD/WDV. The datasheet states:
    > When
    > + * setting the WDDIS bit, and while it is set, the fields WDV and WDD
    > + * must not be modified.
    > + * If the watchdog is enabled, then the timeout can be updated. Else,
    > + * wait that the user enables it.
    > + */
    > + if (wdt_enabled)
    > + wdt_write(wdt, AT91_WDT_MR, wdt->mr &
    > ~AT91_WDT_WDDIS);
    >
    > wdd->timeout = timeout;
    >
    > @@ -145,23 +156,20 @@ static int of_sama5d4_wdt_init(struct device_node *np,
    > struct sama5d4_wdt *wdt)
    >
    > static int sama5d4_wdt_init(struct sama5d4_wdt *wdt) {
    > - struct watchdog_device *wdd = &wdt->wdd;
    > - u32 value = WDT_SEC2TICKS(wdd->timeout);
    > u32 reg;
    > -
    > /*
    > - * Because the fields WDV and WDD must not be modified when the
    > WDDIS
    > - * bit is set, so clear the WDDIS bit before writing the WDT_MR.
    > + * When booting and resuming, the bootloader may have changed the
    > + * watchdog configuration.
    > + * If the watchdog is already running, we can safely update it.
    > + * Else, we have to disable it properly.
    > */
    > - reg = wdt_read(wdt, AT91_WDT_MR);
    > - reg &= ~AT91_WDT_WDDIS;
    > - wdt_write(wdt, AT91_WDT_MR, reg);
    > -
    > - wdt->mr |= AT91_WDT_SET_WDD(value);
    > - wdt->mr |= AT91_WDT_SET_WDV(value);
    > -
    > - wdt_write(wdt, AT91_WDT_MR, wdt->mr);
    > -
    > + if (wdt_enabled) {
    > + wdt_write(wdt, AT91_WDT_MR, wdt->mr);
    > + } else {
    > + reg = wdt_read(wdt, AT91_WDT_MR);
    > + if (!(reg & AT91_WDT_WDDIS))
    > + wdt_write(wdt, AT91_WDT_MR, reg |
    > AT91_WDT_WDDIS);
    > + }
    > return 0;
    > }
    >
    > @@ -172,6 +180,7 @@ static int sama5d4_wdt_probe(struct platform_device
    > *pdev)
    > struct resource *res;
    > void __iomem *regs;
    > u32 irq = 0;
    > + u32 timeout;
    > int ret;
    >
    > wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL); @@ -
    > 221,6 +230,11 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
    > return ret;
    > }
    >
    > + timeout = WDT_SEC2TICKS(wdd->timeout);
    > +
    > + wdt->mr |= AT91_WDT_SET_WDD(timeout);
    > + wdt->mr |= AT91_WDT_SET_WDV(timeout);
    > +
    > ret = sama5d4_wdt_init(wdt);
    > if (ret)
    > return ret;
    > @@ -263,9 +277,7 @@ static int sama5d4_wdt_resume(struct device *dev) {
    > struct sama5d4_wdt *wdt = dev_get_drvdata(dev);
    >
    > - wdt_write(wdt, AT91_WDT_MR, wdt->mr & ~AT91_WDT_WDDIS);
    > - if (wdt->mr & AT91_WDT_WDDIS)
    > - wdt_write(wdt, AT91_WDT_MR, wdt->mr);
    > + sama5d4_wdt_init(wdt);
    >
    > return 0;
    > }
    > --
    > 2.11.0

    Best Regards,
    Wenyou Yang

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