diff mbox series

[07/10] watchdog: rzg2l_wdt: Add suspend/resume support

Message ID 20240122111115.2861835-8-claudiu.beznea.uj@bp.renesas.com
State New
Headers
Series watchdog: rzg2l_wdt: Add support for RZ/G3S |

Commit Message

claudiu beznea Jan. 22, 2024, 11:11 a.m. UTC 
  From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>

The RZ/G3S supports deep sleep states where power to most of the IP blocks
is cut off. To ensure proper working of the watchdog when resuming from
such states, the suspend function is stopping the watchdog and the resume
function is starting it. There is no need to configure the watchdog
in case the watchdog was stopped prior to starting suspend.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
---
 drivers/watchdog/rzg2l_wdt.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

Comments

claudiu beznea Jan. 23, 2024, 7:13 a.m. UTC | #1 
On 22.01.2024 19:39, Guenter Roeck wrote:
> On 1/22/24 03:11, Claudiu wrote:
>> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>>
>> The RZ/G3S supports deep sleep states where power to most of the IP blocks
>> is cut off. To ensure proper working of the watchdog when resuming from
>> such states, the suspend function is stopping the watchdog and the resume
>> function is starting it. There is no need to configure the watchdog
>> in case the watchdog was stopped prior to starting suspend.
>>
>> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>> ---
>>   drivers/watchdog/rzg2l_wdt.c | 26 ++++++++++++++++++++++++++
>>   1 file changed, 26 insertions(+)
>>
>> diff --git a/drivers/watchdog/rzg2l_wdt.c b/drivers/watchdog/rzg2l_wdt.c
>> index 9333dc1a75ab..186796b739f7 100644
>> --- a/drivers/watchdog/rzg2l_wdt.c
>> +++ b/drivers/watchdog/rzg2l_wdt.c
>> @@ -279,6 +279,7 @@ static int rzg2l_wdt_probe(struct platform_device *pdev)
>>       priv->wdev.timeout = WDT_DEFAULT_TIMEOUT;
>>         watchdog_set_drvdata(&priv->wdev, priv);
>> +    dev_set_drvdata(dev, priv);
>>       ret = devm_add_action_or_reset(&pdev->dev, rzg2l_wdt_pm_disable,
>> &priv->wdev);
>>       if (ret)
>>           return ret;
>> @@ -300,10 +301,35 @@ static const struct of_device_id rzg2l_wdt_ids[] = {
>>   };
>>   MODULE_DEVICE_TABLE(of, rzg2l_wdt_ids);
>>   +static int rzg2l_wdt_suspend_late(struct device *dev)
>> +{
>> +    struct rzg2l_wdt_priv *priv = dev_get_drvdata(dev);
>> +
>> +    if (!watchdog_active(&priv->wdev))
>> +        return 0;
>> +
>> +    return rzg2l_wdt_stop(&priv->wdev);
>> +}
>> +
>> +static int rzg2l_wdt_resume_early(struct device *dev)
>> +{
>> +    struct rzg2l_wdt_priv *priv = dev_get_drvdata(dev);
>> +
>> +    if (!watchdog_active(&priv->wdev))
>> +        return 0;
>> +
>> +    return rzg2l_wdt_start(&priv->wdev);
>> +}
>> +
>> +static const struct dev_pm_ops rzg2l_wdt_pm_ops = {
>> +    LATE_SYSTEM_SLEEP_PM_OPS(rzg2l_wdt_suspend_late,
>> rzg2l_wdt_resume_early)
>> +};
>> +
>>   static struct platform_driver rzg2l_wdt_driver = {
>>       .driver = {
>>           .name = "rzg2l_wdt",
>>           .of_match_table = rzg2l_wdt_ids,
>> +        .pm = pm_ptr(&rzg2l_wdt_pm_ops),
> 
> I think this will create a build error if CONFIG_PM=n because rzg2l_wdt_pm_ops
> will be unused but is not marked with __maybe_unused.

The necessity of __maybe_unused has been removed along with the
introduction of LATE_SYSTEM_SLEEP_PM_OPS() and friends (and
*SET_*LATE_SYSTEM_SLEEP_PM_OPS along with the other helpers were marked
deprecated for that) and we can use pm_ptr() along with
LATE_SYSTEM_SLEEP_PM_OPS() to avoid build errors you mentioned.

FYI, I just build the driver with CONFIG_PM=n and all good.

> But then the driver
> won't be
> operational with CONFIG_PM=n, so I really wonder if it makes sense to
> include any
> such conditional code instead of making the driver depend on CONFIG_PM.

That's true. The driver wouldn't work if the CONFIG_PM=n but then it
depends on COMPILE_TEST which is exactly for this (just to compile test it
for platforms that don't support it). I see many watchdog drivers depends
on COMPILE_TEST.

Give this, please let me know would you like me to proceed with it.

Thank you,
Claudiu Beznea

> 
> I really don't think it is desirable to suggest that the driver would work
> with
> CONFIG_PM=n if that isn't really true.
> 
> Guenter
> 
>>       },
>>       .probe = rzg2l_wdt_probe,
>>   };
>
diff mbox series

Patch

diff --git a/drivers/watchdog/rzg2l_wdt.c b/drivers/watchdog/rzg2l_wdt.c
index 9333dc1a75ab..186796b739f7 100644
--- a/drivers/watchdog/rzg2l_wdt.c
+++ b/drivers/watchdog/rzg2l_wdt.c
@@ -279,6 +279,7 @@  static int rzg2l_wdt_probe(struct platform_device *pdev)
 	priv->wdev.timeout = WDT_DEFAULT_TIMEOUT;
 
 	watchdog_set_drvdata(&priv->wdev, priv);
+	dev_set_drvdata(dev, priv);
 	ret = devm_add_action_or_reset(&pdev->dev, rzg2l_wdt_pm_disable, &priv->wdev);
 	if (ret)
 		return ret;
@@ -300,10 +301,35 @@  static const struct of_device_id rzg2l_wdt_ids[] = {
 };
 MODULE_DEVICE_TABLE(of, rzg2l_wdt_ids);
 
+static int rzg2l_wdt_suspend_late(struct device *dev)
+{
+	struct rzg2l_wdt_priv *priv = dev_get_drvdata(dev);
+
+	if (!watchdog_active(&priv->wdev))
+		return 0;
+
+	return rzg2l_wdt_stop(&priv->wdev);
+}
+
+static int rzg2l_wdt_resume_early(struct device *dev)
+{
+	struct rzg2l_wdt_priv *priv = dev_get_drvdata(dev);
+
+	if (!watchdog_active(&priv->wdev))
+		return 0;
+
+	return rzg2l_wdt_start(&priv->wdev);
+}
+
+static const struct dev_pm_ops rzg2l_wdt_pm_ops = {
+	LATE_SYSTEM_SLEEP_PM_OPS(rzg2l_wdt_suspend_late, rzg2l_wdt_resume_early)
+};
+
 static struct platform_driver rzg2l_wdt_driver = {
 	.driver = {
 		.name = "rzg2l_wdt",
 		.of_match_table = rzg2l_wdt_ids,
+		.pm = pm_ptr(&rzg2l_wdt_pm_ops),
 	},
 	.probe = rzg2l_wdt_probe,
 };