[PATCH v2 0/2] watchdog: sama5d4_wdt: Fix WDDIS handling for SAM9X60 and SAMA7G5

[PATCH v2 0/2] watchdog: sama5d4_wdt: Fix WDDIS handling for SAM9X60 and SAMA7G5

[Balakrishnan Sambath]

The sama5d4_wdt driver hardcodes AT91_WDT_WDDIS (bit 15) for WDDIS
detection, which is incorrect for SAM9X60 and SAMA7G5 that use bit 12
(AT91_SAM9X60_WDDIS). This series fixes the detection by introducing
a per-device wddis_mask and documents the bit position difference in
the header.

Changes in v2:
- Reorder patches: fix first, documentation second
- Drop patch 3/3, not needed with wddis_mask approach
- Keep AT91_SAM9X60_* register names, drop _LEGACY/_MODERN naming
- Limit header changes to WDDIS comments and datasheet references

Balakrishnan Sambath (2):
  watchdog: sama5d4_wdt: Fix WDDIS detection on SAM9X60 and SAMA7G5
  watchdog: at91sam9_wdt.h: Document WDDIS bit position per SoC family

 drivers/watchdog/at91sam9_wdt.h |  6 +++--
 drivers/watchdog/sama5d4_wdt.c  | 48 +++++++++++++++------------------
 2 files changed, 25 insertions(+), 29 deletions(-)

-- 
2.34.1

[PATCH 1/2] watchdog: sama5d4_wdt: Fix WDDIS detection on SAM9X60 and SAMA7G5

[Balakrishnan Sambath]

The driver hardcoded AT91_WDT_WDDIS (bit 15) in wdt_enabled and the
probe initial state readout. SAM9X60 and SAMA7G5 use bit 12
(AT91_SAM9X60_WDDIS), causing incorrect WDDIS detection.

Introduce a per-device wddis_mask field to select the correct WDDIS
bit based on the compatible string.

Fixes: 266da53c35fc ("watchdog: sama5d4: readout initial state")
Co-developed-by: Andrei Simion <andrei.simion@microchip.com>
Signed-off-by: Andrei Simion <andrei.simion@microchip.com>
Signed-off-by: Balakrishnan Sambath <balakrishnan.s@microchip.com>
---
 drivers/watchdog/sama5d4_wdt.c | 48 +++++++++++++++-------------------
 1 file changed, 21 insertions(+), 27 deletions(-)

diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c
index 13e72918338a..704b786cc2ec 100644
--- a/drivers/watchdog/sama5d4_wdt.c
+++ b/drivers/watchdog/sama5d4_wdt.c
@@ -24,37 +24,41 @@
 #define WDT_DEFAULT_TIMEOUT	MAX_WDT_TIMEOUT
 
 #define WDT_SEC2TICKS(s)	((s) ? (((s) << 8) - 1) : 0)
 
 struct sama5d4_wdt {
 	struct watchdog_device	wdd;
 	void __iomem		*reg_base;
 	u32			mr;
 	u32			ir;
+	u32			wddis_mask;
 	unsigned long		last_ping;
 	bool			need_irq;
 	bool			sam9x60_support;
 };
 
 static int wdt_timeout;
 static bool nowayout = WATCHDOG_NOWAYOUT;
 
 module_param(wdt_timeout, int, 0);
 MODULE_PARM_DESC(wdt_timeout,
 	"Watchdog timeout in seconds. (default = "
 	__MODULE_STRING(WDT_DEFAULT_TIMEOUT) ")");
 
 module_param(nowayout, bool, 0);
 MODULE_PARM_DESC(nowayout,
 	"Watchdog cannot be stopped once started (default="
 	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 
-#define wdt_enabled (!(wdt->mr & AT91_WDT_WDDIS))
+static inline bool wdt_enabled(struct sama5d4_wdt *wdt)
+{
+	return !(wdt->mr & wdt->wddis_mask);
+}
 
 #define wdt_read(wdt, field) \
 	readl_relaxed((wdt)->reg_base + (field))
 
 /* 4 slow clock periods is 4/32768 = 122.07µs*/
 #define WDT_DELAY	usecs_to_jiffies(123)
 
 static void wdt_write(struct sama5d4_wdt *wdt, u32 field, u32 val)
 {
@@ -75,55 +79,49 @@ static void wdt_write_nosleep(struct sama5d4_wdt *wdt, u32 field, u32 val)
 		udelay(123);
 	writel_relaxed(val, wdt->reg_base + field);
 	wdt->last_ping = jiffies;
 }
 
 static int sama5d4_wdt_start(struct watchdog_device *wdd)
 {
 	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
 
-	if (wdt->sam9x60_support) {
+	if (wdt->sam9x60_support)
 		writel_relaxed(wdt->ir, wdt->reg_base + AT91_SAM9X60_IER);
-		wdt->mr &= ~AT91_SAM9X60_WDDIS;
-	} else {
-		wdt->mr &= ~AT91_WDT_WDDIS;
-	}
+	wdt->mr &= ~wdt->wddis_mask;
 	wdt_write(wdt, AT91_WDT_MR, wdt->mr);
 
 	return 0;
 }
 
 static int sama5d4_wdt_stop(struct watchdog_device *wdd)
 {
 	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
 
-	if (wdt->sam9x60_support) {
+	if (wdt->sam9x60_support)
 		writel_relaxed(wdt->ir, wdt->reg_base + AT91_SAM9X60_IDR);
-		wdt->mr |= AT91_SAM9X60_WDDIS;
-	} else {
-		wdt->mr |= AT91_WDT_WDDIS;
-	}
+	wdt->mr |= wdt->wddis_mask;
 	wdt_write(wdt, AT91_WDT_MR, wdt->mr);
 
 	return 0;
 }
 
 static int sama5d4_wdt_ping(struct watchdog_device *wdd)
 {
 	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
 
 	wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
 
 	return 0;
 }
 
 static int sama5d4_wdt_set_timeout(struct watchdog_device *wdd,
-				 unsigned int timeout)
+				    unsigned int timeout)
 {
 	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
 	u32 value = WDT_SEC2TICKS(timeout);
 
 	if (wdt->sam9x60_support) {
 		wdt_write(wdt, AT91_SAM9X60_WLR,
 			  AT91_SAM9X60_SET_COUNTER(value));
 
 		wdd->timeout = timeout;
@@ -134,20 +132,20 @@ static int sama5d4_wdt_set_timeout(struct watchdog_device *wdd,
 	wdt->mr |= AT91_WDT_SET_WDV(value);
 
 	/*
 	 * WDDIS has to be 0 when updating WDD/WDV. The datasheet states: When
 	 * setting the WDDIS bit, and while it is set, the fields WDV and WDD
 	 * must not be modified.
 	 * If the watchdog is enabled, then the timeout can be updated. Else,
 	 * wait that the user enables it.
 	 */
-	if (wdt_enabled)
-		wdt_write(wdt, AT91_WDT_MR, wdt->mr & ~AT91_WDT_WDDIS);
+	if (wdt_enabled(wdt))
+		wdt_write(wdt, AT91_WDT_MR, wdt->mr & ~wdt->wddis_mask);
 
 	wdd->timeout = timeout;
 
 	return 0;
 }
 
 static const struct watchdog_info sama5d4_wdt_info = {
 	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
 	.identity = "Atmel SAMA5D4 Watchdog",
@@ -178,22 +176,19 @@ static irqreturn_t sama5d4_wdt_irq_handler(int irq, void *dev_id)
 	}
 
 	return IRQ_HANDLED;
 }
 
 static int of_sama5d4_wdt_init(struct device_node *np, struct sama5d4_wdt *wdt)
 {
 	const char *tmp;
 
-	if (wdt->sam9x60_support)
-		wdt->mr = AT91_SAM9X60_WDDIS;
-	else
-		wdt->mr = AT91_WDT_WDDIS;
+	wdt->mr = wdt->wddis_mask;
 
 	if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) &&
 	    !strcmp(tmp, "software"))
 		wdt->need_irq = true;
 
 	if (of_property_read_bool(np, "atmel,idle-halt"))
 		wdt->mr |= AT91_WDT_WDIDLEHLT;
 
 	if (of_property_read_bool(np, "atmel,dbg-halt"))
@@ -207,27 +202,23 @@ static int sama5d4_wdt_init(struct sama5d4_wdt *wdt)
 	u32 reg, val;
 
 	val = WDT_SEC2TICKS(WDT_DEFAULT_TIMEOUT);
 	/*
 	 * When booting and resuming, the bootloader may have changed the
 	 * watchdog configuration.
 	 * If the watchdog is already running, we can safely update it.
 	 * Else, we have to disable it properly.
 	 */
-	if (!wdt_enabled) {
+	if (!wdt_enabled(wdt)) {
 		reg = wdt_read(wdt, AT91_WDT_MR);
-		if (wdt->sam9x60_support && (!(reg & AT91_SAM9X60_WDDIS)))
-			wdt_write_nosleep(wdt, AT91_WDT_MR,
-					  reg | AT91_SAM9X60_WDDIS);
-		else if (!wdt->sam9x60_support &&
-			 (!(reg & AT91_WDT_WDDIS)))
+		if (!(reg & wdt->wddis_mask))
 			wdt_write_nosleep(wdt, AT91_WDT_MR,
-					  reg | AT91_WDT_WDDIS);
+					  reg | wdt->wddis_mask);
 	}
 
 	if (wdt->sam9x60_support) {
 		if (wdt->need_irq)
 			wdt->ir = AT91_SAM9X60_PERINT;
 		else
 			wdt->mr |= AT91_SAM9X60_PERIODRST;
 
 		wdt_write(wdt, AT91_SAM9X60_IER, wdt->ir);
@@ -267,18 +258,21 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
 	wdd->ops = &sama5d4_wdt_ops;
 	wdd->min_timeout = MIN_WDT_TIMEOUT;
 	wdd->max_timeout = MAX_WDT_TIMEOUT;
 	wdt->last_ping = jiffies;
 
 	if (of_device_is_compatible(dev->of_node, "microchip,sam9x60-wdt") ||
 	    of_device_is_compatible(dev->of_node, "microchip,sama7g5-wdt"))
 		wdt->sam9x60_support = true;
 
+	wdt->wddis_mask = wdt->sam9x60_support ? AT91_SAM9X60_WDDIS
+						: AT91_WDT_WDDIS;
+
 	watchdog_set_drvdata(wdd, wdt);
 
 	regs = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(regs))
 		return PTR_ERR(regs);
 
 	wdt->reg_base = regs;
 
 	ret = of_sama5d4_wdt_init(dev->of_node, wdt);
@@ -300,20 +294,20 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
 		if (ret) {
 			dev_err(dev, "cannot register interrupt handler\n");
 			return ret;
 		}
 	}
 
 	watchdog_init_timeout(wdd, wdt_timeout, dev);
 
 	reg = wdt_read(wdt, AT91_WDT_MR);
-	if (!(reg & AT91_WDT_WDDIS)) {
-		wdt->mr &= ~AT91_WDT_WDDIS;
+	if (!(reg & wdt->wddis_mask)) {
+		wdt->mr &= ~wdt->wddis_mask;
 		set_bit(WDOG_HW_RUNNING, &wdd->status);
 	}
 
 	ret = sama5d4_wdt_init(wdt);
 	if (ret)
 		return ret;
 
 	watchdog_set_nowayout(wdd, nowayout);
 
-- 
2.34.1

[PATCH 2/2] watchdog: at91sam9_wdt.h: Document WDDIS bit position per SoC family

[Balakrishnan Sambath]

AT91_WDT_WDDIS (bit 15) applies to SAMA5/AT91SAM9261 and
AT91_SAM9X60_WDDIS (bit 12) to SAM9X60/SAMA7G5/SAM9X75. Update
comments to reflect this and add SAMA7G5 and SAM9X75 datasheet
references to the file header.

Signed-off-by: Balakrishnan Sambath <balakrishnan.s@microchip.com>
---
 drivers/watchdog/at91sam9_wdt.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/watchdog/at91sam9_wdt.h b/drivers/watchdog/at91sam9_wdt.h
index 298d545df1a1..2020694f8f6f 100644
--- a/drivers/watchdog/at91sam9_wdt.h
+++ b/drivers/watchdog/at91sam9_wdt.h
@@ -3,40 +3,42 @@
  * drivers/watchdog/at91sam9_wdt.h
  *
  * Copyright (C) 2007 Andrew Victor
  * Copyright (C) 2007 Atmel Corporation.
  * Copyright (C) 2019 Microchip Technology Inc. and its subsidiaries
  *
  * Watchdog Timer (WDT) - System peripherals regsters.
  * Based on AT91SAM9261 datasheet revision D.
  * Based on SAM9X60 datasheet.
+ * Based on SAMA7G5 datasheet.
+ * Based on SAM9X75 datasheet.
  *
  */
 
 #ifndef AT91_WDT_H
 #define AT91_WDT_H
 
 #include <linux/bits.h>
 
 #define AT91_WDT_CR		0x00			/* Watchdog Control Register */
 #define  AT91_WDT_WDRSTT	BIT(0)			/* Restart */
 #define  AT91_WDT_KEY		(0xa5UL << 24)		/* KEY Password */
 
 #define AT91_WDT_MR		0x04			/* Watchdog Mode Register */
 #define  AT91_WDT_WDV		(0xfffUL << 0)		/* Counter Value */
 #define  AT91_WDT_SET_WDV(x)	((x) & AT91_WDT_WDV)
 #define  AT91_SAM9X60_PERIODRST	BIT(4)		/* Period Reset */
 #define  AT91_SAM9X60_RPTHRST	BIT(5)		/* Minimum Restart Period */
 #define  AT91_WDT_WDFIEN	BIT(12)		/* Fault Interrupt Enable */
-#define  AT91_SAM9X60_WDDIS	BIT(12)		/* Watchdog Disable */
+#define  AT91_SAM9X60_WDDIS	BIT(12)		/* Watchdog Disable (SAM9X60, SAMA7G5, SAM9X75) */
 #define  AT91_WDT_WDRSTEN	BIT(13)		/* Reset Processor */
 #define  AT91_WDT_WDRPROC	BIT(14)		/* Timer Restart */
-#define  AT91_WDT_WDDIS		BIT(15)		/* Watchdog Disable */
+#define  AT91_WDT_WDDIS		BIT(15)		/* Watchdog Disable (SAMA5, AT91SAM9261) */
 #define  AT91_WDT_WDD		(0xfffUL << 16)		/* Delta Value */
 #define  AT91_WDT_SET_WDD(x)	(((x) << 16) & AT91_WDT_WDD)
 #define  AT91_WDT_WDDBGHLT	BIT(28)		/* Debug Halt */
 #define  AT91_WDT_WDIDLEHLT	BIT(29)		/* Idle Halt */
 
 #define AT91_WDT_SR		0x08		/* Watchdog Status Register */
 #define  AT91_WDT_WDUNF		BIT(0)		/* Watchdog Underflow */
 #define  AT91_WDT_WDERR		BIT(1)		/* Watchdog Error */
 
-- 
2.34.1

Re: [PATCH 1/2] watchdog: sama5d4_wdt: Fix WDDIS detection on SAM9X60 and SAMA7G5

[Alexandre Belloni]

On 02/03/2026 17:03:09+0530, Balakrishnan Sambath wrote:
> The driver hardcoded AT91_WDT_WDDIS (bit 15) in wdt_enabled and the
> probe initial state readout. SAM9X60 and SAMA7G5 use bit 12
> (AT91_SAM9X60_WDDIS), causing incorrect WDDIS detection.
> 
> Introduce a per-device wddis_mask field to select the correct WDDIS
> bit based on the compatible string.
> 
> Fixes: 266da53c35fc ("watchdog: sama5d4: readout initial state")
> Co-developed-by: Andrei Simion <andrei.simion@microchip.com>
> Signed-off-by: Andrei Simion <andrei.simion@microchip.com>
> Signed-off-by: Balakrishnan Sambath <balakrishnan.s@microchip.com>
Reviewed-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

> ---
>  drivers/watchdog/sama5d4_wdt.c | 48 +++++++++++++++-------------------
>  1 file changed, 21 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c
> index 13e72918338a..704b786cc2ec 100644
> --- a/drivers/watchdog/sama5d4_wdt.c
> +++ b/drivers/watchdog/sama5d4_wdt.c
> @@ -24,37 +24,41 @@
>  #define WDT_DEFAULT_TIMEOUT	MAX_WDT_TIMEOUT
>  
>  #define WDT_SEC2TICKS(s)	((s) ? (((s) << 8) - 1) : 0)
>  
>  struct sama5d4_wdt {
>  	struct watchdog_device	wdd;
>  	void __iomem		*reg_base;
>  	u32			mr;
>  	u32			ir;
> +	u32			wddis_mask;
>  	unsigned long		last_ping;
>  	bool			need_irq;
>  	bool			sam9x60_support;
>  };
>  
>  static int wdt_timeout;
>  static bool nowayout = WATCHDOG_NOWAYOUT;
>  
>  module_param(wdt_timeout, int, 0);
>  MODULE_PARM_DESC(wdt_timeout,
>  	"Watchdog timeout in seconds. (default = "
>  	__MODULE_STRING(WDT_DEFAULT_TIMEOUT) ")");
>  
>  module_param(nowayout, bool, 0);
>  MODULE_PARM_DESC(nowayout,
>  	"Watchdog cannot be stopped once started (default="
>  	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
>  
> -#define wdt_enabled (!(wdt->mr & AT91_WDT_WDDIS))
> +static inline bool wdt_enabled(struct sama5d4_wdt *wdt)
> +{
> +	return !(wdt->mr & wdt->wddis_mask);
> +}
>  
>  #define wdt_read(wdt, field) \
>  	readl_relaxed((wdt)->reg_base + (field))
>  
>  /* 4 slow clock periods is 4/32768 = 122.07µs*/
>  #define WDT_DELAY	usecs_to_jiffies(123)
>  
>  static void wdt_write(struct sama5d4_wdt *wdt, u32 field, u32 val)
>  {
> @@ -75,55 +79,49 @@ static void wdt_write_nosleep(struct sama5d4_wdt *wdt, u32 field, u32 val)
>  		udelay(123);
>  	writel_relaxed(val, wdt->reg_base + field);
>  	wdt->last_ping = jiffies;
>  }
>  
>  static int sama5d4_wdt_start(struct watchdog_device *wdd)
>  {
>  	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
>  
> -	if (wdt->sam9x60_support) {
> +	if (wdt->sam9x60_support)
>  		writel_relaxed(wdt->ir, wdt->reg_base + AT91_SAM9X60_IER);
> -		wdt->mr &= ~AT91_SAM9X60_WDDIS;
> -	} else {
> -		wdt->mr &= ~AT91_WDT_WDDIS;
> -	}
> +	wdt->mr &= ~wdt->wddis_mask;
>  	wdt_write(wdt, AT91_WDT_MR, wdt->mr);
>  
>  	return 0;
>  }
>  
>  static int sama5d4_wdt_stop(struct watchdog_device *wdd)
>  {
>  	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
>  
> -	if (wdt->sam9x60_support) {
> +	if (wdt->sam9x60_support)
>  		writel_relaxed(wdt->ir, wdt->reg_base + AT91_SAM9X60_IDR);
> -		wdt->mr |= AT91_SAM9X60_WDDIS;
> -	} else {
> -		wdt->mr |= AT91_WDT_WDDIS;
> -	}
> +	wdt->mr |= wdt->wddis_mask;
>  	wdt_write(wdt, AT91_WDT_MR, wdt->mr);
>  
>  	return 0;
>  }
>  
>  static int sama5d4_wdt_ping(struct watchdog_device *wdd)
>  {
>  	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
>  
>  	wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
>  
>  	return 0;
>  }
>  
>  static int sama5d4_wdt_set_timeout(struct watchdog_device *wdd,
> -				 unsigned int timeout)
> +				    unsigned int timeout)
>  {
>  	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
>  	u32 value = WDT_SEC2TICKS(timeout);
>  
>  	if (wdt->sam9x60_support) {
>  		wdt_write(wdt, AT91_SAM9X60_WLR,
>  			  AT91_SAM9X60_SET_COUNTER(value));
>  
>  		wdd->timeout = timeout;
> @@ -134,20 +132,20 @@ static int sama5d4_wdt_set_timeout(struct watchdog_device *wdd,
>  	wdt->mr |= AT91_WDT_SET_WDV(value);
>  
>  	/*
>  	 * WDDIS has to be 0 when updating WDD/WDV. The datasheet states: When
>  	 * setting the WDDIS bit, and while it is set, the fields WDV and WDD
>  	 * must not be modified.
>  	 * If the watchdog is enabled, then the timeout can be updated. Else,
>  	 * wait that the user enables it.
>  	 */
> -	if (wdt_enabled)
> -		wdt_write(wdt, AT91_WDT_MR, wdt->mr & ~AT91_WDT_WDDIS);
> +	if (wdt_enabled(wdt))
> +		wdt_write(wdt, AT91_WDT_MR, wdt->mr & ~wdt->wddis_mask);
>  
>  	wdd->timeout = timeout;
>  
>  	return 0;
>  }
>  
>  static const struct watchdog_info sama5d4_wdt_info = {
>  	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
>  	.identity = "Atmel SAMA5D4 Watchdog",
> @@ -178,22 +176,19 @@ static irqreturn_t sama5d4_wdt_irq_handler(int irq, void *dev_id)
>  	}
>  
>  	return IRQ_HANDLED;
>  }
>  
>  static int of_sama5d4_wdt_init(struct device_node *np, struct sama5d4_wdt *wdt)
>  {
>  	const char *tmp;
>  
> -	if (wdt->sam9x60_support)
> -		wdt->mr = AT91_SAM9X60_WDDIS;
> -	else
> -		wdt->mr = AT91_WDT_WDDIS;
> +	wdt->mr = wdt->wddis_mask;
>  
>  	if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) &&
>  	    !strcmp(tmp, "software"))
>  		wdt->need_irq = true;
>  
>  	if (of_property_read_bool(np, "atmel,idle-halt"))
>  		wdt->mr |= AT91_WDT_WDIDLEHLT;
>  
>  	if (of_property_read_bool(np, "atmel,dbg-halt"))
> @@ -207,27 +202,23 @@ static int sama5d4_wdt_init(struct sama5d4_wdt *wdt)
>  	u32 reg, val;
>  
>  	val = WDT_SEC2TICKS(WDT_DEFAULT_TIMEOUT);
>  	/*
>  	 * When booting and resuming, the bootloader may have changed the
>  	 * watchdog configuration.
>  	 * If the watchdog is already running, we can safely update it.
>  	 * Else, we have to disable it properly.
>  	 */
> -	if (!wdt_enabled) {
> +	if (!wdt_enabled(wdt)) {
>  		reg = wdt_read(wdt, AT91_WDT_MR);
> -		if (wdt->sam9x60_support && (!(reg & AT91_SAM9X60_WDDIS)))
> -			wdt_write_nosleep(wdt, AT91_WDT_MR,
> -					  reg | AT91_SAM9X60_WDDIS);
> -		else if (!wdt->sam9x60_support &&
> -			 (!(reg & AT91_WDT_WDDIS)))
> +		if (!(reg & wdt->wddis_mask))
>  			wdt_write_nosleep(wdt, AT91_WDT_MR,
> -					  reg | AT91_WDT_WDDIS);
> +					  reg | wdt->wddis_mask);
>  	}
>  
>  	if (wdt->sam9x60_support) {
>  		if (wdt->need_irq)
>  			wdt->ir = AT91_SAM9X60_PERINT;
>  		else
>  			wdt->mr |= AT91_SAM9X60_PERIODRST;
>  
>  		wdt_write(wdt, AT91_SAM9X60_IER, wdt->ir);
> @@ -267,18 +258,21 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
>  	wdd->ops = &sama5d4_wdt_ops;
>  	wdd->min_timeout = MIN_WDT_TIMEOUT;
>  	wdd->max_timeout = MAX_WDT_TIMEOUT;
>  	wdt->last_ping = jiffies;
>  
>  	if (of_device_is_compatible(dev->of_node, "microchip,sam9x60-wdt") ||
>  	    of_device_is_compatible(dev->of_node, "microchip,sama7g5-wdt"))
>  		wdt->sam9x60_support = true;
>  
> +	wdt->wddis_mask = wdt->sam9x60_support ? AT91_SAM9X60_WDDIS
> +						: AT91_WDT_WDDIS;
> +
>  	watchdog_set_drvdata(wdd, wdt);
>  
>  	regs = devm_platform_ioremap_resource(pdev, 0);
>  	if (IS_ERR(regs))
>  		return PTR_ERR(regs);
>  
>  	wdt->reg_base = regs;
>  
>  	ret = of_sama5d4_wdt_init(dev->of_node, wdt);
> @@ -300,20 +294,20 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
>  		if (ret) {
>  			dev_err(dev, "cannot register interrupt handler\n");
>  			return ret;
>  		}
>  	}
>  
>  	watchdog_init_timeout(wdd, wdt_timeout, dev);
>  
>  	reg = wdt_read(wdt, AT91_WDT_MR);
> -	if (!(reg & AT91_WDT_WDDIS)) {
> -		wdt->mr &= ~AT91_WDT_WDDIS;
> +	if (!(reg & wdt->wddis_mask)) {
> +		wdt->mr &= ~wdt->wddis_mask;
>  		set_bit(WDOG_HW_RUNNING, &wdd->status);
>  	}
>  
>  	ret = sama5d4_wdt_init(wdt);
>  	if (ret)
>  		return ret;
>  
>  	watchdog_set_nowayout(wdd, nowayout);
>  
> -- 
> 2.34.1
> 

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

Re: [PATCH 2/2] watchdog: at91sam9_wdt.h: Document WDDIS bit position per SoC family

[Alexandre Belloni]

On 02/03/2026 17:03:10+0530, Balakrishnan Sambath wrote:
> AT91_WDT_WDDIS (bit 15) applies to SAMA5/AT91SAM9261 and
> AT91_SAM9X60_WDDIS (bit 12) to SAM9X60/SAMA7G5/SAM9X75. Update
> comments to reflect this and add SAMA7G5 and SAM9X75 datasheet
> references to the file header.
> 
> Signed-off-by: Balakrishnan Sambath <balakrishnan.s@microchip.com>
Reviewed-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

> ---
>  drivers/watchdog/at91sam9_wdt.h | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/watchdog/at91sam9_wdt.h b/drivers/watchdog/at91sam9_wdt.h
> index 298d545df1a1..2020694f8f6f 100644
> --- a/drivers/watchdog/at91sam9_wdt.h
> +++ b/drivers/watchdog/at91sam9_wdt.h
> @@ -3,40 +3,42 @@
>   * drivers/watchdog/at91sam9_wdt.h
>   *
>   * Copyright (C) 2007 Andrew Victor
>   * Copyright (C) 2007 Atmel Corporation.
>   * Copyright (C) 2019 Microchip Technology Inc. and its subsidiaries
>   *
>   * Watchdog Timer (WDT) - System peripherals regsters.
>   * Based on AT91SAM9261 datasheet revision D.
>   * Based on SAM9X60 datasheet.
> + * Based on SAMA7G5 datasheet.
> + * Based on SAM9X75 datasheet.
>   *
>   */
>  
>  #ifndef AT91_WDT_H
>  #define AT91_WDT_H
>  
>  #include <linux/bits.h>
>  
>  #define AT91_WDT_CR		0x00			/* Watchdog Control Register */
>  #define  AT91_WDT_WDRSTT	BIT(0)			/* Restart */
>  #define  AT91_WDT_KEY		(0xa5UL << 24)		/* KEY Password */
>  
>  #define AT91_WDT_MR		0x04			/* Watchdog Mode Register */
>  #define  AT91_WDT_WDV		(0xfffUL << 0)		/* Counter Value */
>  #define  AT91_WDT_SET_WDV(x)	((x) & AT91_WDT_WDV)
>  #define  AT91_SAM9X60_PERIODRST	BIT(4)		/* Period Reset */
>  #define  AT91_SAM9X60_RPTHRST	BIT(5)		/* Minimum Restart Period */
>  #define  AT91_WDT_WDFIEN	BIT(12)		/* Fault Interrupt Enable */
> -#define  AT91_SAM9X60_WDDIS	BIT(12)		/* Watchdog Disable */
> +#define  AT91_SAM9X60_WDDIS	BIT(12)		/* Watchdog Disable (SAM9X60, SAMA7G5, SAM9X75) */
>  #define  AT91_WDT_WDRSTEN	BIT(13)		/* Reset Processor */
>  #define  AT91_WDT_WDRPROC	BIT(14)		/* Timer Restart */
> -#define  AT91_WDT_WDDIS		BIT(15)		/* Watchdog Disable */
> +#define  AT91_WDT_WDDIS		BIT(15)		/* Watchdog Disable (SAMA5, AT91SAM9261) */
>  #define  AT91_WDT_WDD		(0xfffUL << 16)		/* Delta Value */
>  #define  AT91_WDT_SET_WDD(x)	(((x) << 16) & AT91_WDT_WDD)
>  #define  AT91_WDT_WDDBGHLT	BIT(28)		/* Debug Halt */
>  #define  AT91_WDT_WDIDLEHLT	BIT(29)		/* Idle Halt */
>  
>  #define AT91_WDT_SR		0x08		/* Watchdog Status Register */
>  #define  AT91_WDT_WDUNF		BIT(0)		/* Watchdog Underflow */
>  #define  AT91_WDT_WDERR		BIT(1)		/* Watchdog Error */
>  
> -- 
> 2.34.1
> 

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com