[PATCHv2 0/3] watchdog: sama5d4: fix IRQ and timeout bugs, use platform_get_irq_optional

[PATCHv2 0/3] watchdog: sama5d4: fix IRQ and timeout bugs, use platform_get_irq_optional

[Rosen Penev]

This series fixes three issues in the sama5d4 watchdog driver:

Patch 1: Return IRQ_NONE when the status register indicates no watchdog
interrupt is pending, and pass the configured timeout (not the hardcoded
default) to sama5d4_wdt_init().

Patch 2: Replace irq_of_parse_and_map() with platform_get_irq_optional()
for simpler error handling and EPROBE_DEFER support.

Patch 3: Move platform_set_drvdata() before devm_request_irq() to prevent
a NULL pointer dereference in the interrupt handler if the shared System
IRQ fires immediately after registration.

v2: address sashiko review

Rosen Penev (3):
  watchdog: sama5d4: fix shared IRQ and hardcoded timeout issues
  watchdog: sama5d4: use platform_get_irq_optional()
  watchdog: sama5d4: fix NULL deref in irq handler

 drivers/watchdog/sama5d4_wdt.c | 32 +++++++++++++++++---------------
 1 file changed, 17 insertions(+), 15 deletions(-)

--
2.54.0

[PATCHv2 1/3] watchdog: sama5d4: fix shared IRQ and hardcoded timeout issues

[Rosen Penev]

Fix three pre-existing issues in the sama5d4 watchdog driver:

1. Unsafe IRQF_SHARED | IRQF_NO_SUSPEND combination: The watchdog
   interrupt is a dedicated peripheral line, not shared with other
   devices.

2. Unconditional IRQ_HANDLED on shared line: The handler returned
   IRQ_HANDLED even when the status register indicated no watchdog
   interrupt was pending.  Return IRQ_NONE in that case so the kernel
   can properly detect spurious interrupts on the line.

3. Hardcoded 16-second timeout: sama5d4_wdt_init() unconditionally
   used WDT_DEFAULT_TIMEOUT (16s) for the hardware timeout, ignoring
   any timeout configured via device tree (watchdog_init_timeout) or
   userspace.  Pass wdd->timeout to sama5d4_wdt_init() so the
   configured timeout is honored during probe and resume.

Assisted-by: opencode:big-pickle
Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 drivers/watchdog/sama5d4_wdt.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c
index 704b786cc2ec..f74f1e8956b5 100644
--- a/drivers/watchdog/sama5d4_wdt.c
+++ b/drivers/watchdog/sama5d4_wdt.c
@@ -169,11 +169,12 @@ static irqreturn_t sama5d4_wdt_irq_handler(int irq, void *dev_id)
 	else
 		reg = wdt_read(wdt, AT91_WDT_SR);
 
-	if (reg) {
-		pr_crit("Atmel Watchdog Software Reset\n");
-		emergency_restart();
-		pr_crit("Reboot didn't succeed\n");
-	}
+	if (!reg)
+		return IRQ_NONE;
+
+	pr_crit("Atmel Watchdog Software Reset\n");
+	emergency_restart();
+	pr_crit("Reboot didn't succeed\n");
 
 	return IRQ_HANDLED;
 }
@@ -197,11 +198,11 @@ static int of_sama5d4_wdt_init(struct device_node *np, struct sama5d4_wdt *wdt)
 	return 0;
 }
 
-static int sama5d4_wdt_init(struct sama5d4_wdt *wdt)
+static int sama5d4_wdt_init(struct sama5d4_wdt *wdt, unsigned int timeout)
 {
 	u32 reg, val;
 
-	val = WDT_SEC2TICKS(WDT_DEFAULT_TIMEOUT);
+	val = WDT_SEC2TICKS(timeout);
 	/*
 	 * When booting and resuming, the bootloader may have changed the
 	 * watchdog configuration.
@@ -305,7 +306,7 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
 		set_bit(WDOG_HW_RUNNING, &wdd->status);
 	}
 
-	ret = sama5d4_wdt_init(wdt);
+	ret = sama5d4_wdt_init(wdt, wdd->timeout);
 	if (ret)
 		return ret;
 
@@ -358,7 +359,7 @@ static int sama5d4_wdt_resume_early(struct device *dev)
 	 * This should only be done when the registers are lost on suspend but
 	 * there is no way to get this information right now.
 	 */
-	sama5d4_wdt_init(wdt);
+	sama5d4_wdt_init(wdt, wdt->wdd.timeout);
 
 	if (watchdog_active(&wdt->wdd))
 		sama5d4_wdt_start(&wdt->wdd);
-- 
2.54.0

[PATCHv2 2/3] watchdog: sama5d4: use platform_get_irq_optional()

[Rosen Penev]

irq_of_parse_and_map() requires irq_dispose_mapping() on failure. Don't
bother with it as platform_get_irq_optional() doesn't need it.

Also handle EPROBE_DEFER.

Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 drivers/watchdog/sama5d4_wdt.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c
index f74f1e8956b5..2536e2f2ab32 100644
--- a/drivers/watchdog/sama5d4_wdt.c
+++ b/drivers/watchdog/sama5d4_wdt.c
@@ -11,7 +11,6 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
-#include <linux/of_irq.h>
 #include <linux/platform_device.h>
 #include <linux/reboot.h>
 #include <linux/watchdog.h>
@@ -245,7 +244,7 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
 	struct watchdog_device *wdd;
 	struct sama5d4_wdt *wdt;
 	void __iomem *regs;
-	u32 irq = 0;
+	int irq = 0;
 	u32 reg;
 	int ret;
 
@@ -281,8 +280,11 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
 		return ret;
 
 	if (wdt->need_irq) {
-		irq = irq_of_parse_and_map(dev->of_node, 0);
-		if (!irq) {
+		irq = platform_get_irq_optional(pdev, 0);
+		if (irq == -EPROBE_DEFER)
+			return irq;
+
+		if (irq < 0) {
 			dev_warn(dev, "failed to get IRQ from DT\n");
 			wdt->need_irq = false;
 		}
-- 
2.54.0

[PATCHv2 3/3] watchdog: sama5d4: fix NULL deref in irq handler

[Rosen Penev]

Move platform_set_drvdata() before devm_request_irq() so that the
interrupt handler can safely dereference the driver data via
platform_get_drvdata().  An interrupt on the shared System IRQ line
(SAM9X60/SAM9X7) could fire between request_irq and the late
platform_set_drvdata() call, causing the handler to dereference NULL.

Assisted-by: opencode:big-pickle
Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 drivers/watchdog/sama5d4_wdt.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c
index 2536e2f2ab32..7cd6f35c8e21 100644
--- a/drivers/watchdog/sama5d4_wdt.c
+++ b/drivers/watchdog/sama5d4_wdt.c
@@ -268,6 +268,7 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
 						: AT91_WDT_WDDIS;
 
 	watchdog_set_drvdata(wdd, wdt);
+	platform_set_drvdata(pdev, wdt);
 
 	regs = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(regs))
@@ -319,8 +320,6 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
-	platform_set_drvdata(pdev, wdt);
-
 	dev_info(dev, "initialized (timeout = %d sec, nowayout = %d)\n",
 		 wdd->timeout, nowayout);
 
-- 
2.54.0

Re: [PATCHv2 0/3] watchdog: sama5d4: fix IRQ and timeout bugs, use platform_get_irq_optional

[Nicolas Ferre]

On 08/06/2026 at 13:09, Rosen Penev wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> This series fixes three issues in the sama5d4 watchdog driver:
> 
> Patch 1: Return IRQ_NONE when the status register indicates no watchdog
> interrupt is pending, and pass the configured timeout (not the hardcoded
> default) to sama5d4_wdt_init().
> 
> Patch 2: Replace irq_of_parse_and_map() with platform_get_irq_optional()
> for simpler error handling and EPROBE_DEFER support.
> 
> Patch 3: Move platform_set_drvdata() before devm_request_irq() to prevent
> a NULL pointer dereference in the interrupt handler if the shared System
> IRQ fires immediately after registration.
> 
> v2: address sashiko review

Rosen,

I'd like to hear how these issues where found and how the patches were 
tested.

Best regards,
   Nicolas

> Rosen Penev (3):
>    watchdog: sama5d4: fix shared IRQ and hardcoded timeout issues
>    watchdog: sama5d4: use platform_get_irq_optional()
>    watchdog: sama5d4: fix NULL deref in irq handler
> 
>   drivers/watchdog/sama5d4_wdt.c | 32 +++++++++++++++++---------------
>   1 file changed, 17 insertions(+), 15 deletions(-)
> 
> --
> 2.54.0
> 

Re: [PATCHv2 0/3] watchdog: sama5d4: fix IRQ and timeout bugs, use platform_get_irq_optional

[Rosen Penev]

On Mon, Jun 8, 2026 at 1:38 PM Nicolas Ferre
<nicolas.ferre@microchip.com> wrote:
>
> On 08/06/2026 at 13:09, Rosen Penev wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> >
> > This series fixes three issues in the sama5d4 watchdog driver:
> >
> > Patch 1: Return IRQ_NONE when the status register indicates no watchdog
> > interrupt is pending, and pass the configured timeout (not the hardcoded
> > default) to sama5d4_wdt_init().
> >
> > Patch 2: Replace irq_of_parse_and_map() with platform_get_irq_optional()
> > for simpler error handling and EPROBE_DEFER support.
> >
> > Patch 3: Move platform_set_drvdata() before devm_request_irq() to prevent
> > a NULL pointer dereference in the interrupt handler if the shared System
> > IRQ fires immediately after registration.
> >
> > v2: address sashiko review
>
> Rosen,
>
> I'd like to hear how these issues where found and how the patches were
> tested.
They were not. Maintainer has explicitly asked me to fix issues
discovered by https://sashiko.dev

I originally only had patch 2, which is true of multiple places.
>
> Best regards,
>    Nicolas
>
> > Rosen Penev (3):
> >    watchdog: sama5d4: fix shared IRQ and hardcoded timeout issues
> >    watchdog: sama5d4: use platform_get_irq_optional()
> >    watchdog: sama5d4: fix NULL deref in irq handler
> >
> >   drivers/watchdog/sama5d4_wdt.c | 32 +++++++++++++++++---------------
> >   1 file changed, 17 insertions(+), 15 deletions(-)
> >
> > --
> > 2.54.0
> >
>