> -----Original Message-----
> From: Alexandre Belloni [mailto:alexandre.bell...@free-electrons.com]
> Sent: 2017年3月3日 1:31
> To: Guenter Roeck <li...@roeck-us.net>
> Cc: Wim Van Sebroeck <w...@iguana.be>; Nicolas Ferre - M43238
> <nicolas.fe...@microchip.com>; Wenyou Yang - A41535
> <wenyou.y...@microchip.com>; linux-watch...@vger.kernel.org; linux-arm-
> ker...@lists.infradead.org; linux-kernel@vger.kernel.org; Alexandre Belloni
> <alexandre.bell...@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.y...@microchip.com>
>
> Signed-off-by: Alexandre Belloni <alexandre.bell...@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
