linux-kernel - [PATCH v4] platform/x86: portwell-ec: Add suspend/resume support for watchdog

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Message-ID: <c9cfe602-c279-4aa4-9932-76f47f26556c@portwell.com.tw>
Date: Thu, 28 Aug 2025 13:31:17 +0800
From: Yen-Chi Huang <jesse.huang@...twell.com.tw>
To: hdegoede@...hat.com, ilpo.jarvinen@...ux.intel.com,
 wim@...ux-watchdog.org, linux@...ck-us.net
Cc: linux-kernel@...r.kernel.org, platform-driver-x86@...r.kernel.org,
 linux-watchdog@...r.kernel.org, jay.chen@...onical.com,
 jesse.huang@...twell.com.tw
Subject: [PATCH v4] platform/x86: portwell-ec: Add suspend/resume support for
 watchdog

Portwell EC does not disable the watchdog during suspend. To avoid unwanted
resets, this patch adds suspend and resume callbacks (pwec_suspend() and
pwec_resume()) to the driver.

The watchdog is stopped in pwec_suspend() and restarted in pwec_resume() if
it was active before suspend.

Signed-off-by: Yen-Chi Huang <jesse.huang@...twell.com.tw>
---
V3->v4:
  - Switch from legacy .suspend/.resume callbacks to .pm with
    DEFINE_SIMPLE_DEV_PM_OPS and pm_sleep_ptr(), as suggested by Ilpo.
---
 drivers/platform/x86/portwell-ec.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/platform/x86/portwell-ec.c b/drivers/platform/x86/portwell-ec.c
index 322f296e9315..d2e91d5c3b3a 100644
--- a/drivers/platform/x86/portwell-ec.c
+++ b/drivers/platform/x86/portwell-ec.c
@@ -30,6 +30,7 @@
 #include <linux/ioport.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
+#include <linux/pm.h>
 #include <linux/sizes.h>
 #include <linux/string.h>
 #include <linux/watchdog.h>
@@ -246,9 +247,28 @@ static int pwec_probe(struct platform_device *pdev)
 	return 0;
 }
 
+static int pwec_suspend(struct device *dev)
+{
+	if (watchdog_active(&ec_wdt_dev))
+		return pwec_wdt_stop(&ec_wdt_dev);
+3
+	return 0;
+}
+
+static int pwec_resume(struct device *dev)
+{
+	if (watchdog_active(&ec_wdt_dev))
+		return pwec_wdt_start(&ec_wdt_dev);
+
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(pwec_dev_pm_ops, pwec_suspend, pwec_resume);
+
 static struct platform_driver pwec_driver = {
 	.driver = {
 		.name = "portwell-ec",
+		.pm = pm_sleep_ptr(&pwec_dev_pm_ops),
 	},
 	.probe = pwec_probe,
 };
-- 
2.34.1