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

Balakrishnan Sambath
2026-03-02T11:33:47Z

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