linux-kernel - [PATCH v3 RESEND 3/5] watchdog: s3c2410_wdt: Increase max timeout value of watchdog

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Message-Id: <20250714055440.3138135-4-sw617.shin@samsung.com>
Date: Mon, 14 Jul 2025 14:54:38 +0900
From: Sangwook Shin <sw617.shin@...sung.com>
To: krzk@...nel.org, alim.akhtar@...sung.com, wim@...ux-watchdog.org,
	linux@...ck-us.net
Cc: linux-arm-kernel@...ts.infradead.org, linux-samsung-soc@...r.kernel.org,
	linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org, Sangwook Shin
	<sw617.shin@...sung.com>
Subject: [PATCH v3 RESEND 3/5] watchdog: s3c2410_wdt: Increase max timeout
 value of watchdog

Increase max_timeout value from 55s to 3664647s (1017h 57min 27s) with
38400000 frequency system if the system has 32-bit WTCNT register.

cat /sys/devices/platform/10060000.watchdog_cl0/watchdog/watchdog0/max_timeout
3664647

[    0.302473] s3c2410-wdt 10060000.watchdog_cl0: Heartbeat: count=1099394100000, timeout=3664647, freq=300000
[    0.302479] s3c2410-wdt 10060000.watchdog_cl0: Heartbeat: timeout=3664647, divisor=256, count=1099394100000 (fff8feac)
[    0.302510] s3c2410-wdt 10060000.watchdog_cl0: starting watchdog timer
[    0.302722] s3c2410-wdt 10060000.watchdog_cl0: watchdog active, reset enabled, irq disabled

If system has 32-bit WTCNT, add QUIRK_HAS_32BIT_MAXCNT to its quirk flags, then
it will operation with 32-bit counter. If not, with 16-bit counter like previous.

Signed-off-by: Sangwook Shin <sw617.shin@...sung.com>
---
 drivers/watchdog/s3c2410_wdt.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c
index 31f7e1ec779e..090b78717cd2 100644
--- a/drivers/watchdog/s3c2410_wdt.c
+++ b/drivers/watchdog/s3c2410_wdt.c
@@ -34,6 +34,7 @@
 #define S3C2410_WTCLRINT	0x0c
 
 #define S3C2410_WTCNT_MAXCNT	0xffff
+#define S3C2410_WTCNT_MAXCNT_32	0xffffffff
 
 #define S3C2410_WTCON_RSTEN		BIT(0)
 #define S3C2410_WTCON_INTEN		BIT(2)
@@ -123,6 +124,10 @@
  * %QUIRK_HAS_DBGACK_BIT: WTCON register has DBGACK_MASK bit. Setting the
  * DBGACK_MASK bit disables the watchdog outputs when the SoC is in debug mode.
  * Debug mode is determined by the DBGACK CPU signal.
+ *
+ * %QUIRK_HAS_32BIT_MAXCNT: WTDAT and WTCNT are 32-bit registers. With these
+ * 32-bit registers, larger values to be set, which means that larger timeouts
+ * value can be set.
  */
 #define QUIRK_HAS_WTCLRINT_REG			BIT(0)
 #define QUIRK_HAS_PMU_MASK_RESET		BIT(1)
@@ -130,6 +135,7 @@
 #define QUIRK_HAS_PMU_AUTO_DISABLE		BIT(3)
 #define QUIRK_HAS_PMU_CNT_EN			BIT(4)
 #define QUIRK_HAS_DBGACK_BIT			BIT(5)
+#define QUIRK_HAS_32BIT_MAXCNT			BIT(6)
 
 /* These quirks require that we have a PMU register map */
 #define QUIRKS_HAVE_PMUREG \
@@ -198,6 +204,7 @@ struct s3c2410_wdt {
 	struct notifier_block	freq_transition;
 	const struct s3c2410_wdt_variant *drv_data;
 	struct regmap *pmureg;
+	unsigned int		max_cnt;
 };
 
 static const struct s3c2410_wdt_variant drv_data_s3c2410 = {
@@ -411,7 +418,7 @@ static inline unsigned int s3c2410wdt_max_timeout(struct s3c2410_wdt *wdt)
 {
 	const unsigned long freq = s3c2410wdt_get_freq(wdt);
 
-	return S3C2410_WTCNT_MAXCNT / DIV_ROUND_UP(freq,
+	return wdt->max_cnt / DIV_ROUND_UP(freq,
 		(S3C2410_WTCON_PRESCALE_MAX + 1) * S3C2410_WTCON_MAXDIV);
 }
 
@@ -566,7 +573,7 @@ static int s3c2410wdt_set_heartbeat(struct watchdog_device *wdd,
 {
 	struct s3c2410_wdt *wdt = watchdog_get_drvdata(wdd);
 	unsigned long freq = s3c2410wdt_get_freq(wdt);
-	unsigned int count;
+	unsigned long count;
 	unsigned int divisor = 1;
 	unsigned long wtcon;
 
@@ -576,7 +583,7 @@ static int s3c2410wdt_set_heartbeat(struct watchdog_device *wdd,
 	freq = DIV_ROUND_UP(freq, 128);
 	count = timeout * freq;
 
-	dev_dbg(wdt->dev, "Heartbeat: count=%d, timeout=%d, freq=%lu\n",
+	dev_dbg(wdt->dev, "Heartbeat: count=%lu, timeout=%d, freq=%lu\n",
 		count, timeout, freq);
 
 	/* if the count is bigger than the watchdog register,
@@ -584,8 +591,8 @@ static int s3c2410wdt_set_heartbeat(struct watchdog_device *wdd,
 	   actually make this value
 	*/
 
-	if (count >= 0x10000) {
-		divisor = DIV_ROUND_UP(count, 0xffff);
+	if (count > wdt->max_cnt) {
+		divisor = DIV_ROUND_UP(count, wdt->max_cnt);
 
 		if (divisor > S3C2410_WTCON_PRESCALE_MAX + 1) {
 			dev_err(wdt->dev, "timeout %d too big\n", timeout);
@@ -593,7 +600,7 @@ static int s3c2410wdt_set_heartbeat(struct watchdog_device *wdd,
 		}
 	}
 
-	dev_dbg(wdt->dev, "Heartbeat: timeout=%d, divisor=%d, count=%d (%08x)\n",
+	dev_dbg(wdt->dev, "Heartbeat: timeout=%d, divisor=%d, count=%lu (%08lx)\n",
 		timeout, divisor, count, DIV_ROUND_UP(count, divisor));
 
 	count = DIV_ROUND_UP(count, divisor);
@@ -801,6 +808,10 @@ static int s3c2410wdt_probe(struct platform_device *pdev)
 	if (IS_ERR(wdt->src_clk))
 		return dev_err_probe(dev, PTR_ERR(wdt->src_clk), "failed to get source clock\n");
 
+	wdt->max_cnt = S3C2410_WTCNT_MAXCNT;
+	if ((wdt->drv_data->quirks & QUIRK_HAS_32BIT_MAXCNT))
+		wdt->max_cnt = S3C2410_WTCNT_MAXCNT_32;
+
 	wdt->wdt_device.min_timeout = 1;
 	wdt->wdt_device.max_timeout = s3c2410wdt_max_timeout(wdt);
 
-- 
2.25.1