On Thu, Jan 27, 2022 at 08:47:39PM +1000, Alistair Francis wrote:
> The i.MX watchdog cannot be disabled by software once it has been
> enabled. This means that it can't be stopped before suspend.
>
> For systems that enter low power mode this is fine, as the watchdog will
> be automatically stopped by hardware in low power mode. Not all i.MX
> platforms support low power mode in the mainline kernel. For example the
> i.MX7D does not enter low power mode and so will be rebooted 2 minutes
> after entering sleep states.
>
> This patch introduces a device tree property "fsl,ping-during-suspend"
> that can be used to enable ping on suspend support for these systems.
>
> Signed-off-by: Alistair Francis <alistair@xxxxxxxxxxxxx>
Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> ---
> v3:
> - Fixup typos in commit message
> v2:
> - Remove custom property
>
> drivers/watchdog/imx2_wdt.c | 27 ++++++++++++++++++++-------
> 1 file changed, 20 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/watchdog/imx2_wdt.c b/drivers/watchdog/imx2_wdt.c
> index 51bfb796898b..d0c5d47ddede 100644
> --- a/drivers/watchdog/imx2_wdt.c
> +++ b/drivers/watchdog/imx2_wdt.c
> @@ -66,6 +66,7 @@ struct imx2_wdt_device {
> struct watchdog_device wdog;
> bool ext_reset;
> bool clk_is_on;
> + bool no_ping;
> };
>
> static bool nowayout = WATCHDOG_NOWAYOUT;
> @@ -312,12 +313,18 @@ static int __init imx2_wdt_probe(struct platform_device *pdev)
>
> wdev->ext_reset = of_property_read_bool(dev->of_node,
> "fsl,ext-reset-output");
> + /*
> + * The i.MX7D doesn't support low power mode, so we need to ping the watchdog
> + * during suspend.
> + */
> + wdev->no_ping = !of_device_is_compatible(dev->of_node, "fsl,imx7d-wdt");
> platform_set_drvdata(pdev, wdog);
> watchdog_set_drvdata(wdog, wdev);
> watchdog_set_nowayout(wdog, nowayout);
> watchdog_set_restart_priority(wdog, 128);
> watchdog_init_timeout(wdog, timeout, dev);
> - watchdog_stop_ping_on_suspend(wdog);
> + if (wdev->no_ping)
> + watchdog_stop_ping_on_suspend(wdog);
>
> if (imx2_wdt_is_running(wdev)) {
> imx2_wdt_set_timeout(wdog, wdog->timeout);
> @@ -366,9 +373,11 @@ static int __maybe_unused imx2_wdt_suspend(struct device *dev)
> imx2_wdt_ping(wdog);
> }
>
> - clk_disable_unprepare(wdev->clk);
> + if (wdev->no_ping) {
> + clk_disable_unprepare(wdev->clk);
>
> - wdev->clk_is_on = false;
> + wdev->clk_is_on = false;
> + }
>
> return 0;
> }
> @@ -380,11 +389,14 @@ static int __maybe_unused imx2_wdt_resume(struct device *dev)
> struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
> int ret;
>
> - ret = clk_prepare_enable(wdev->clk);
> - if (ret)
> - return ret;
> + if (wdev->no_ping) {
> + ret = clk_prepare_enable(wdev->clk);
>
> - wdev->clk_is_on = true;
> + if (ret)
> + return ret;
> +
> + wdev->clk_is_on = true;
> + }
>
> if (watchdog_active(wdog) && !imx2_wdt_is_running(wdev)) {
> /*
> @@ -407,6 +419,7 @@ static SIMPLE_DEV_PM_OPS(imx2_wdt_pm_ops, imx2_wdt_suspend,
>
> static const struct of_device_id imx2_wdt_dt_ids[] = {
> { .compatible = "fsl,imx21-wdt", },
> + { .compatible = "fsl,imx7d-wdt", },
> { /* sentinel */ }
> };
> MODULE_DEVICE_TABLE(of, imx2_wdt_dt_ids);
