diff mbox series

[v5] watchdog: imx2_wdg: Allow ping on suspend

Message ID 20220330094552.31039-1-alistair@alistair23.me
State New
Headers show
Series [v5] watchdog: imx2_wdg: Allow ping on suspend | expand

Commit Message

Alistair Francis March 30, 2022, 9:45 a.m. UTC
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 the "fsl,imx7d-wdt" compatible string
which enables ping on suspend support. This allows the i.MX7D systems to
suspend without triggering the watchdog.

Signed-off-by: Alistair Francis <alistair@alistair23.me>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
---
v5:
 - Fixup commit message description
v4:
 - Fix spelling on allow/alow in title

 drivers/watchdog/imx2_wdt.c | 27 ++++++++++++++++++++-------
 1 file changed, 20 insertions(+), 7 deletions(-)

Comments

Guenter Roeck April 1, 2022, 2:47 a.m. UTC | #1
On 3/30/22 02:45, 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 the "fsl,imx7d-wdt" compatible string
> which enables ping on suspend support. This allows the i.MX7D systems to
> suspend without triggering the watchdog.
> 
> Signed-off-by: Alistair Francis <alistair@alistair23.me>
> Reviewed-by: Guenter Roeck <linux@roeck-us.net>
> ---
> v5:
>   - Fixup commit message description

Too late ;-)

Guenter

> v4:
>   - Fix spelling on allow/alow in title
> 
>   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);
diff mbox series

Patch

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);