[PATCH v8 0/3] clocksource: fix Tegra234 SoC Watchdog Timer.

[PATCH v8 0/3] clocksource: fix Tegra234 SoC Watchdog Timer.

[Robert Lin]

From: robelin <robelin@nvidia.com>

This set of patches includes a fix for watchdog for it may not bark
due to self-pinging and adds WDIOC_GETTIMELEFT support.

--
V8:
- Change WARN_ON() to WARN_ON_ONCE() to not spew too many message
- Use pre-exist DIV_ROUND_CLOSEST_ULL for the same math operation

V7:
- Fix formatting
- Consider overflow and warn if happens

V6:
- Fix timeleft value addition using unmatched time unit
- Use u64 type to maintain the microseconds value in case of overflow

V5:
- Print warning message if get unexpected value from the register

V4:
- Improve the precision of timeleft value
- Fix the unused variable warning

V3:
- Improve comment description
- Refactor to fit codeline within 80 columns
- Remove unused if(0) blocks


V2:
- Fix a compilation error, a warning and updates copyright
--


Pohsun Su (2):
  clocksource/drivers/timer-tegra186: add WDIOC_GETTIMELEFT support
  clocksource/drivers/timer-tegra186: fix watchdog self-pinging

robelin (1):
  clocksource/drivers/timer-tegra186: Remove unused bits

 drivers/clocksource/timer-tegra186.c | 100 +++++++++++++++++----------
 1 file changed, 63 insertions(+), 37 deletions(-)

-- 
2.34.1

[PATCH v8 1/3] clocksource/drivers/timer-tegra186: add WDIOC_GETTIMELEFT support

[Robert Lin]

From: Pohsun Su <pohsuns@nvidia.com>

This change adds support for WDIOC_GETTIMELEFT so userspace
programs can get the number of seconds before system reset by
the watchdog timer via ioctl.

Signed-off-by: Pohsun Su <pohsuns@nvidia.com>
Signed-off-by: Robert Lin <robelin@nvidia.com>
---
 drivers/clocksource/timer-tegra186.c | 64 +++++++++++++++++++++++++++-
 1 file changed, 63 insertions(+), 1 deletion(-)

diff --git a/drivers/clocksource/timer-tegra186.c b/drivers/clocksource/timer-tegra186.c
index ea742889ee06..e3ea6110e6f5 100644
--- a/drivers/clocksource/timer-tegra186.c
+++ b/drivers/clocksource/timer-tegra186.c
@@ -1,8 +1,9 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * Copyright (c) 2019-2020 NVIDIA Corporation. All rights reserved.
+ * Copyright (c) 2019-2025 NVIDIA Corporation. All rights reserved.
  */
 
+#include <linux/bitfield.h>
 #include <linux/clocksource.h>
 #include <linux/module.h>
 #include <linux/interrupt.h>
@@ -30,6 +31,7 @@
 
 #define TMRSR 0x004
 #define  TMRSR_INTR_CLR BIT(30)
+#define  TMRSR_PCV GENMASK(28, 0)
 
 #define TMRCSSR 0x008
 #define  TMRCSSR_SRC_USEC (0 << 0)
@@ -46,6 +48,9 @@
 #define  WDTCR_TIMER_SOURCE_MASK 0xf
 #define  WDTCR_TIMER_SOURCE(x) ((x) & 0xf)
 
+#define WDTSR 0x004
+#define  WDTSR_CURRENT_EXPIRATION_COUNT GENMASK(14, 12)
+
 #define WDTCMDR 0x008
 #define  WDTCMDR_DISABLE_COUNTER BIT(1)
 #define  WDTCMDR_START_COUNTER BIT(0)
@@ -235,12 +240,69 @@ static int tegra186_wdt_set_timeout(struct watchdog_device *wdd,
 	return 0;
 }
 
+static unsigned int tegra186_wdt_get_timeleft(struct watchdog_device *wdd)
+{
+	struct tegra186_wdt *wdt = to_tegra186_wdt(wdd);
+	u32 expiration, val;
+	u64 timeleft;
+
+	if (!watchdog_active(&wdt->base)) {
+		/* return zero if the watchdog timer is not activated. */
+		return 0;
+	}
+
+	/*
+	 * Reset occurs on the fifth expiration of the
+	 * watchdog timer and so when the watchdog timer is configured,
+	 * the actual value programmed into the counter is 1/5 of the
+	 * timeout value. Once the counter reaches 0, expiration count
+	 * will be increased by 1 and the down counter restarts.
+	 * Hence to get the time left before system reset we must
+	 * combine 2 parts:
+	 * 1. value of the current down counter
+	 * 2. (number of counter expirations remaining) * (timeout/5)
+	 */
+
+	/* Get the current number of counter expirations. Should be a
+	 * value between 0 and 4
+	 */
+	val = readl_relaxed(wdt->regs + WDTSR);
+	expiration = FIELD_GET(WDTSR_CURRENT_EXPIRATION_COUNT, val);
+	if (WARN_ON_ONCE(expiration > 4))
+		return 0;
+
+	/* Get the current counter value in microsecond. */
+	val = readl_relaxed(wdt->tmr->regs + TMRSR);
+	timeleft = FIELD_GET(TMRSR_PCV, val);
+
+	/*
+	 * Calculate the time remaining by adding the time for the
+	 * counter value to the time of the counter expirations that
+	 * remain.
+	 */
+	timeleft += (((u64)wdt->base.timeout * USEC_PER_SEC) / 5) * (4 - expiration);
+
+	/*
+	 * Convert the current counter value to seconds,
+	 * rounding up to the nearest second. Cast u64 to
+	 * u32 under the assumption that no overflow happens
+	 * when coverting to seconds.
+	 */
+	timeleft = DIV_ROUND_CLOSEST_ULL(timeleft, USEC_PER_SEC);
+
+	if (WARN_ON_ONCE(timeleft > U32_MAX))
+		return U32_MAX;
+
+	return lower_32_bits(timeleft);
+}
+
 static const struct watchdog_ops tegra186_wdt_ops = {
 	.owner = THIS_MODULE,
 	.start = tegra186_wdt_start,
 	.stop = tegra186_wdt_stop,
 	.ping = tegra186_wdt_ping,
 	.set_timeout = tegra186_wdt_set_timeout,
+	.get_timeleft = tegra186_wdt_get_timeleft,
 };
 
 static struct tegra186_wdt *tegra186_wdt_create(struct tegra186_timer *tegra,
-- 
2.34.1

[PATCH v8 2/3] clocksource/drivers/timer-tegra186: fix watchdog self-pinging

[Robert Lin]

From: Pohsun Su <pohsuns@nvidia.com>

This change removes watchdog self-pinging behavior.

The timer irq handler is triggered due to the 1st expiration,
the handler disables and enables watchdog but also implicitly
clears the expiration count so the count can only be 0 or 1.

Since this watchdog supports opened, configured, or pinged by
systemd, We remove this behavior or the watchdog may not bark
when systemd crashes since the 5th expiration never comes.

Signed-off-by: Pohsun Su <pohsuns@nvidia.com>
Signed-off-by: Robert Lin <robelin@nvidia.com>
---
 drivers/clocksource/timer-tegra186.c | 27 ---------------------------
 1 file changed, 27 deletions(-)

diff --git a/drivers/clocksource/timer-tegra186.c b/drivers/clocksource/timer-tegra186.c
index e3ea6110e6f5..20685d122b47 100644
--- a/drivers/clocksource/timer-tegra186.c
+++ b/drivers/clocksource/timer-tegra186.c
@@ -175,9 +175,6 @@ static void tegra186_wdt_enable(struct tegra186_wdt *wdt)
 		value &= ~WDTCR_PERIOD_MASK;
 		value |= WDTCR_PERIOD(1);
 
-		/* enable local interrupt for WDT petting */
-		value |= WDTCR_LOCAL_INT_ENABLE;
-
 		/* enable local FIQ and remote interrupt for debug dump */
 		if (0)
 			value |= WDTCR_REMOTE_INT_ENABLE |
@@ -428,23 +425,10 @@ static int tegra186_timer_usec_init(struct tegra186_timer *tegra)
 	return clocksource_register_hz(&tegra->usec, USEC_PER_SEC);
 }
 
-static irqreturn_t tegra186_timer_irq(int irq, void *data)
-{
-	struct tegra186_timer *tegra = data;
-
-	if (watchdog_active(&tegra->wdt->base)) {
-		tegra186_wdt_disable(tegra->wdt);
-		tegra186_wdt_enable(tegra->wdt);
-	}
-
-	return IRQ_HANDLED;
-}
-
 static int tegra186_timer_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct tegra186_timer *tegra;
-	unsigned int irq;
 	int err;
 
 	tegra = devm_kzalloc(dev, sizeof(*tegra), GFP_KERNEL);
@@ -463,8 +447,6 @@ static int tegra186_timer_probe(struct platform_device *pdev)
 	if (err < 0)
 		return err;
 
-	irq = err;
-
 	/* create a watchdog using a preconfigured timer */
 	tegra->wdt = tegra186_wdt_create(tegra, 0);
 	if (IS_ERR(tegra->wdt)) {
@@ -491,17 +473,8 @@ static int tegra186_timer_probe(struct platform_device *pdev)
 		goto unregister_osc;
 	}
 
-	err = devm_request_irq(dev, irq, tegra186_timer_irq, 0,
-			       "tegra186-timer", tegra);
-	if (err < 0) {
-		dev_err(dev, "failed to request IRQ#%u: %d\n", irq, err);
-		goto unregister_usec;
-	}
-
 	return 0;
 
-unregister_usec:
-	clocksource_unregister(&tegra->usec);
 unregister_osc:
 	clocksource_unregister(&tegra->osc);
 unregister_tsc:
-- 
2.34.1

[PATCH v8 3/3] clocksource/drivers/timer-tegra186: Remove unused bits

[Robert Lin]

From: robelin <robelin@nvidia.com>

The intention to keep the unsed if(0) block is gone now. Remove
them for clean codes.

Signed-off-by: robelin <robelin@nvidia.com>
---
 drivers/clocksource/timer-tegra186.c | 9 ---------
 1 file changed, 9 deletions(-)

diff --git a/drivers/clocksource/timer-tegra186.c b/drivers/clocksource/timer-tegra186.c
index 20685d122b47..940168458122 100644
--- a/drivers/clocksource/timer-tegra186.c
+++ b/drivers/clocksource/timer-tegra186.c
@@ -175,15 +175,6 @@ static void tegra186_wdt_enable(struct tegra186_wdt *wdt)
 		value &= ~WDTCR_PERIOD_MASK;
 		value |= WDTCR_PERIOD(1);
 
-		/* enable local FIQ and remote interrupt for debug dump */
-		if (0)
-			value |= WDTCR_REMOTE_INT_ENABLE |
-				 WDTCR_LOCAL_FIQ_ENABLE;
-
-		/* enable system debug reset (doesn't properly reboot) */
-		if (0)
-			value |= WDTCR_SYSTEM_DEBUG_RESET_ENABLE;
-
 		/* enable system POR reset */
 		value |= WDTCR_SYSTEM_POR_RESET_ENABLE;
 
-- 
2.34.1

Re: [PATCH v8 0/3] clocksource: fix Tegra234 SoC Watchdog Timer.

[Daniel Lezcano]

On Wed, May 07, 2025 at 12:43:08PM +0800, Robert Lin wrote:
> From: robelin <robelin@nvidia.com>
> 
> This set of patches includes a fix for watchdog for it may not bark
> due to self-pinging and adds WDIOC_GETTIMELEFT support.
> 
> --
> V8:
> - Change WARN_ON() to WARN_ON_ONCE() to not spew too many message
> - Use pre-exist DIV_ROUND_CLOSEST_ULL for the same math operation
> 
> V7:
> - Fix formatting
> - Consider overflow and warn if happens
> 
> V6:
> - Fix timeleft value addition using unmatched time unit
> - Use u64 type to maintain the microseconds value in case of overflow
> 
> V5:
> - Print warning message if get unexpected value from the register
> 
> V4:
> - Improve the precision of timeleft value
> - Fix the unused variable warning
> 
> V3:
> - Improve comment description
> - Refactor to fit codeline within 80 columns
> - Remove unused if(0) blocks
> 
> 
> V2:
> - Fix a compilation error, a warning and updates copyright
> --

Applied, thanks

-- 

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[tip: timers/clocksource] clocksource/drivers/timer-tegra186: Remove unused bits

[tip-bot2 for robelin]

The following commit has been merged into the timers/clocksource branch of tip:

Commit-ID:     39b27ddf4d680fc908b2fc788039406e2e1c4601
Gitweb:        https://git.kernel.org/tip/39b27ddf4d680fc908b2fc788039406e2e1c4601
Author:        robelin <robelin@nvidia.com>
AuthorDate:    Wed, 07 May 2025 12:43:11 +08:00
Committer:     Daniel Lezcano <daniel.lezcano@linaro.org>
CommitterDate: Fri, 16 May 2025 11:10:33 +02:00

clocksource/drivers/timer-tegra186: Remove unused bits

The intention to keep the unsed if(0) block is gone now. Remove
them for clean codes.

Signed-off-by: robelin <robelin@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/20250507044311.3751033-4-robelin@nvidia.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
---
 drivers/clocksource/timer-tegra186.c |  9 ---------
 1 file changed, 9 deletions(-)

diff --git a/drivers/clocksource/timer-tegra186.c b/drivers/clocksource/timer-tegra186.c
index fb8a51a..e5394f9 100644
--- a/drivers/clocksource/timer-tegra186.c
+++ b/drivers/clocksource/timer-tegra186.c
@@ -174,15 +174,6 @@ static void tegra186_wdt_enable(struct tegra186_wdt *wdt)
 		value &= ~WDTCR_PERIOD_MASK;
 		value |= WDTCR_PERIOD(1);
 
-		/* enable local FIQ and remote interrupt for debug dump */
-		if (0)
-			value |= WDTCR_REMOTE_INT_ENABLE |
-				 WDTCR_LOCAL_FIQ_ENABLE;
-
-		/* enable system debug reset (doesn't properly reboot) */
-		if (0)
-			value |= WDTCR_SYSTEM_DEBUG_RESET_ENABLE;
-
 		/* enable system POR reset */
 		value |= WDTCR_SYSTEM_POR_RESET_ENABLE;
 

[tip: timers/clocksource] clocksource/drivers/timer-tegra186: Fix watchdog self-pinging

[tip-bot2 for Pohsun Su]

The following commit has been merged into the timers/clocksource branch of tip:

Commit-ID:     b42d781e0350c969ef8155b800e33400f5f8b8a6
Gitweb:        https://git.kernel.org/tip/b42d781e0350c969ef8155b800e33400f5f8b8a6
Author:        Pohsun Su <pohsuns@nvidia.com>
AuthorDate:    Wed, 07 May 2025 12:43:10 +08:00
Committer:     Daniel Lezcano <daniel.lezcano@linaro.org>
CommitterDate: Fri, 16 May 2025 11:10:32 +02:00

clocksource/drivers/timer-tegra186: Fix watchdog self-pinging

This change removes watchdog self-pinging behavior.

The timer irq handler is triggered due to the 1st expiration,
the handler disables and enables watchdog but also implicitly
clears the expiration count so the count can only be 0 or 1.

Since this watchdog supports opened, configured, or pinged by
systemd, We remove this behavior or the watchdog may not bark
when systemd crashes since the 5th expiration never comes.

Signed-off-by: Pohsun Su <pohsuns@nvidia.com>
Signed-off-by: Robert Lin <robelin@nvidia.com>
Link: https://lore.kernel.org/r/20250507044311.3751033-3-robelin@nvidia.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
---
 drivers/clocksource/timer-tegra186.c | 27 +---------------------------
 1 file changed, 27 deletions(-)

diff --git a/drivers/clocksource/timer-tegra186.c b/drivers/clocksource/timer-tegra186.c
index 5eb6b7e..fb8a51a 100644
--- a/drivers/clocksource/timer-tegra186.c
+++ b/drivers/clocksource/timer-tegra186.c
@@ -174,9 +174,6 @@ static void tegra186_wdt_enable(struct tegra186_wdt *wdt)
 		value &= ~WDTCR_PERIOD_MASK;
 		value |= WDTCR_PERIOD(1);
 
-		/* enable local interrupt for WDT petting */
-		value |= WDTCR_LOCAL_INT_ENABLE;
-
 		/* enable local FIQ and remote interrupt for debug dump */
 		if (0)
 			value |= WDTCR_REMOTE_INT_ENABLE |
@@ -427,23 +424,10 @@ static int tegra186_timer_usec_init(struct tegra186_timer *tegra)
 	return clocksource_register_hz(&tegra->usec, USEC_PER_SEC);
 }
 
-static irqreturn_t tegra186_timer_irq(int irq, void *data)
-{
-	struct tegra186_timer *tegra = data;
-
-	if (watchdog_active(&tegra->wdt->base)) {
-		tegra186_wdt_disable(tegra->wdt);
-		tegra186_wdt_enable(tegra->wdt);
-	}
-
-	return IRQ_HANDLED;
-}
-
 static int tegra186_timer_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct tegra186_timer *tegra;
-	unsigned int irq;
 	int err;
 
 	tegra = devm_kzalloc(dev, sizeof(*tegra), GFP_KERNEL);
@@ -462,8 +446,6 @@ static int tegra186_timer_probe(struct platform_device *pdev)
 	if (err < 0)
 		return err;
 
-	irq = err;
-
 	/* create a watchdog using a preconfigured timer */
 	tegra->wdt = tegra186_wdt_create(tegra, 0);
 	if (IS_ERR(tegra->wdt)) {
@@ -490,17 +472,8 @@ static int tegra186_timer_probe(struct platform_device *pdev)
 		goto unregister_osc;
 	}
 
-	err = devm_request_irq(dev, irq, tegra186_timer_irq, 0,
-			       "tegra186-timer", tegra);
-	if (err < 0) {
-		dev_err(dev, "failed to request IRQ#%u: %d\n", irq, err);
-		goto unregister_usec;
-	}
-
 	return 0;
 
-unregister_usec:
-	clocksource_unregister(&tegra->usec);
 unregister_osc:
 	clocksource_unregister(&tegra->osc);
 unregister_tsc:

[tip: timers/clocksource] clocksource/drivers/timer-tegra186: Add WDIOC_GETTIMELEFT support

[tip-bot2 for Pohsun Su]

The following commit has been merged into the timers/clocksource branch of tip:

Commit-ID:     28c842c8b0f5d1c2da823b11326e63cdfdbc3def
Gitweb:        https://git.kernel.org/tip/28c842c8b0f5d1c2da823b11326e63cdfdbc3def
Author:        Pohsun Su <pohsuns@nvidia.com>
AuthorDate:    Wed, 07 May 2025 12:43:09 +08:00
Committer:     Daniel Lezcano <daniel.lezcano@linaro.org>
CommitterDate: Fri, 16 May 2025 11:10:32 +02:00

clocksource/drivers/timer-tegra186: Add WDIOC_GETTIMELEFT support

This change adds support for WDIOC_GETTIMELEFT so userspace
programs can get the number of seconds before system reset by
the watchdog timer via ioctl.

Signed-off-by: Pohsun Su <pohsuns@nvidia.com>
Signed-off-by: Robert Lin <robelin@nvidia.com>
Link: https://lore.kernel.org/r/20250507044311.3751033-2-robelin@nvidia.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
---
 drivers/clocksource/timer-tegra186.c | 64 ++++++++++++++++++++++++++-
 1 file changed, 63 insertions(+), 1 deletion(-)

diff --git a/drivers/clocksource/timer-tegra186.c b/drivers/clocksource/timer-tegra186.c
index 5d4cf52..5eb6b7e 100644
--- a/drivers/clocksource/timer-tegra186.c
+++ b/drivers/clocksource/timer-tegra186.c
@@ -1,8 +1,9 @@
 // SPDX-License-Identifier: GPL-2.0-only
 /*
- * Copyright (c) 2019-2020 NVIDIA Corporation. All rights reserved.
+ * Copyright (c) 2019-2025 NVIDIA Corporation. All rights reserved.
  */
 
+#include <linux/bitfield.h>
 #include <linux/clocksource.h>
 #include <linux/module.h>
 #include <linux/interrupt.h>
@@ -29,6 +30,7 @@
 
 #define TMRSR 0x004
 #define  TMRSR_INTR_CLR BIT(30)
+#define  TMRSR_PCV GENMASK(28, 0)
 
 #define TMRCSSR 0x008
 #define  TMRCSSR_SRC_USEC (0 << 0)
@@ -45,6 +47,9 @@
 #define  WDTCR_TIMER_SOURCE_MASK 0xf
 #define  WDTCR_TIMER_SOURCE(x) ((x) & 0xf)
 
+#define WDTSR 0x004
+#define  WDTSR_CURRENT_EXPIRATION_COUNT GENMASK(14, 12)
+
 #define WDTCMDR 0x008
 #define  WDTCMDR_DISABLE_COUNTER BIT(1)
 #define  WDTCMDR_START_COUNTER BIT(0)
@@ -234,12 +239,69 @@ static int tegra186_wdt_set_timeout(struct watchdog_device *wdd,
 	return 0;
 }
 
+static unsigned int tegra186_wdt_get_timeleft(struct watchdog_device *wdd)
+{
+	struct tegra186_wdt *wdt = to_tegra186_wdt(wdd);
+	u32 expiration, val;
+	u64 timeleft;
+
+	if (!watchdog_active(&wdt->base)) {
+		/* return zero if the watchdog timer is not activated. */
+		return 0;
+	}
+
+	/*
+	 * Reset occurs on the fifth expiration of the
+	 * watchdog timer and so when the watchdog timer is configured,
+	 * the actual value programmed into the counter is 1/5 of the
+	 * timeout value. Once the counter reaches 0, expiration count
+	 * will be increased by 1 and the down counter restarts.
+	 * Hence to get the time left before system reset we must
+	 * combine 2 parts:
+	 * 1. value of the current down counter
+	 * 2. (number of counter expirations remaining) * (timeout/5)
+	 */
+
+	/* Get the current number of counter expirations. Should be a
+	 * value between 0 and 4
+	 */
+	val = readl_relaxed(wdt->regs + WDTSR);
+	expiration = FIELD_GET(WDTSR_CURRENT_EXPIRATION_COUNT, val);
+	if (WARN_ON_ONCE(expiration > 4))
+		return 0;
+
+	/* Get the current counter value in microsecond. */
+	val = readl_relaxed(wdt->tmr->regs + TMRSR);
+	timeleft = FIELD_GET(TMRSR_PCV, val);
+
+	/*
+	 * Calculate the time remaining by adding the time for the
+	 * counter value to the time of the counter expirations that
+	 * remain.
+	 */
+	timeleft += (((u64)wdt->base.timeout * USEC_PER_SEC) / 5) * (4 - expiration);
+
+	/*
+	 * Convert the current counter value to seconds,
+	 * rounding up to the nearest second. Cast u64 to
+	 * u32 under the assumption that no overflow happens
+	 * when coverting to seconds.
+	 */
+	timeleft = DIV_ROUND_CLOSEST_ULL(timeleft, USEC_PER_SEC);
+
+	if (WARN_ON_ONCE(timeleft > U32_MAX))
+		return U32_MAX;
+
+	return lower_32_bits(timeleft);
+}
+
 static const struct watchdog_ops tegra186_wdt_ops = {
 	.owner = THIS_MODULE,
 	.start = tegra186_wdt_start,
 	.stop = tegra186_wdt_stop,
 	.ping = tegra186_wdt_ping,
 	.set_timeout = tegra186_wdt_set_timeout,
+	.get_timeleft = tegra186_wdt_get_timeleft,
 };
 
 static struct tegra186_wdt *tegra186_wdt_create(struct tegra186_timer *tegra,

Re: [PATCH v8 1/3] clocksource/drivers/timer-tegra186: add WDIOC_GETTIMELEFT support

[Guenter Roeck]

Hi,

On Wed, May 07, 2025 at 12:43:09PM +0800, Robert Lin wrote:
> From: Pohsun Su <pohsuns@nvidia.com>
> 
> This change adds support for WDIOC_GETTIMELEFT so userspace
> programs can get the number of seconds before system reset by
> the watchdog timer via ioctl.
> 
> Signed-off-by: Pohsun Su <pohsuns@nvidia.com>
> Signed-off-by: Robert Lin <robelin@nvidia.com>
> ---
>  drivers/clocksource/timer-tegra186.c | 64 +++++++++++++++++++++++++++-
>  1 file changed, 63 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/clocksource/timer-tegra186.c b/drivers/clocksource/timer-tegra186.c
> index ea742889ee06..e3ea6110e6f5 100644
> --- a/drivers/clocksource/timer-tegra186.c
> +++ b/drivers/clocksource/timer-tegra186.c
> @@ -1,8 +1,9 @@
>  // SPDX-License-Identifier: GPL-2.0-only
>  /*
> - * Copyright (c) 2019-2020 NVIDIA Corporation. All rights reserved.
> + * Copyright (c) 2019-2025 NVIDIA Corporation. All rights reserved.
>   */
>  
> +#include <linux/bitfield.h>
>  #include <linux/clocksource.h>
>  #include <linux/module.h>
>  #include <linux/interrupt.h>
> @@ -30,6 +31,7 @@
>  
>  #define TMRSR 0x004
>  #define  TMRSR_INTR_CLR BIT(30)
> +#define  TMRSR_PCV GENMASK(28, 0)
>  
>  #define TMRCSSR 0x008
>  #define  TMRCSSR_SRC_USEC (0 << 0)
> @@ -46,6 +48,9 @@
>  #define  WDTCR_TIMER_SOURCE_MASK 0xf
>  #define  WDTCR_TIMER_SOURCE(x) ((x) & 0xf)
>  
> +#define WDTSR 0x004
> +#define  WDTSR_CURRENT_EXPIRATION_COUNT GENMASK(14, 12)
> +
>  #define WDTCMDR 0x008
>  #define  WDTCMDR_DISABLE_COUNTER BIT(1)
>  #define  WDTCMDR_START_COUNTER BIT(0)
> @@ -235,12 +240,69 @@ static int tegra186_wdt_set_timeout(struct watchdog_device *wdd,
>  	return 0;
>  }
>  
> +static unsigned int tegra186_wdt_get_timeleft(struct watchdog_device *wdd)
> +{
> +	struct tegra186_wdt *wdt = to_tegra186_wdt(wdd);
> +	u32 expiration, val;
> +	u64 timeleft;
> +
> +	if (!watchdog_active(&wdt->base)) {
> +		/* return zero if the watchdog timer is not activated. */
> +		return 0;
> +	}
> +
> +	/*
> +	 * Reset occurs on the fifth expiration of the
> +	 * watchdog timer and so when the watchdog timer is configured,
> +	 * the actual value programmed into the counter is 1/5 of the
> +	 * timeout value. Once the counter reaches 0, expiration count
> +	 * will be increased by 1 and the down counter restarts.
> +	 * Hence to get the time left before system reset we must
> +	 * combine 2 parts:
> +	 * 1. value of the current down counter
> +	 * 2. (number of counter expirations remaining) * (timeout/5)
> +	 */
> +
> +	/* Get the current number of counter expirations. Should be a
> +	 * value between 0 and 4
> +	 */
> +	val = readl_relaxed(wdt->regs + WDTSR);
> +	expiration = FIELD_GET(WDTSR_CURRENT_EXPIRATION_COUNT, val);
> +	if (WARN_ON_ONCE(expiration > 4))
> +		return 0;
> +
> +	/* Get the current counter value in microsecond. */
> +	val = readl_relaxed(wdt->tmr->regs + TMRSR);
> +	timeleft = FIELD_GET(TMRSR_PCV, val);
> +
> +	/*
> +	 * Calculate the time remaining by adding the time for the
> +	 * counter value to the time of the counter expirations that
> +	 * remain.
> +	 */
> +	timeleft += (((u64)wdt->base.timeout * USEC_PER_SEC) / 5) * (4 - expiration);

This results in

xtensa-linux-ld: drivers/clocksource/timer-tegra186.o: in function `tegra186_timer_remove':
timer-tegra186.c:(.text+0x350): undefined reference to `__udivdi3'
xtensa-linux-ld: drivers/clocksource/timer-tegra186.o: in function `tegra186_wdt_get_timeleft':
timer-tegra186.c:(.text+0x52c): undefined reference to `__udivdi3'

when trying to build xtensa:allmodconfig.

Guenter

Re: [PATCH v8 1/3] clocksource/drivers/timer-tegra186: add WDIOC_GETTIMELEFT support

[Thierry Reding]

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On Fri, Jun 13, 2025 at 06:24:40AM -0700, Guenter Roeck wrote:
> Hi,
> 
> On Wed, May 07, 2025 at 12:43:09PM +0800, Robert Lin wrote:
> > From: Pohsun Su <pohsuns@nvidia.com>
> > 
> > This change adds support for WDIOC_GETTIMELEFT so userspace
> > programs can get the number of seconds before system reset by
> > the watchdog timer via ioctl.
> > 
> > Signed-off-by: Pohsun Su <pohsuns@nvidia.com>
> > Signed-off-by: Robert Lin <robelin@nvidia.com>
> > ---
> >  drivers/clocksource/timer-tegra186.c | 64 +++++++++++++++++++++++++++-
> >  1 file changed, 63 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/clocksource/timer-tegra186.c b/drivers/clocksource/timer-tegra186.c
> > index ea742889ee06..e3ea6110e6f5 100644
> > --- a/drivers/clocksource/timer-tegra186.c
> > +++ b/drivers/clocksource/timer-tegra186.c
> > @@ -1,8 +1,9 @@
> >  // SPDX-License-Identifier: GPL-2.0-only
> >  /*
> > - * Copyright (c) 2019-2020 NVIDIA Corporation. All rights reserved.
> > + * Copyright (c) 2019-2025 NVIDIA Corporation. All rights reserved.
> >   */
> >  
> > +#include <linux/bitfield.h>
> >  #include <linux/clocksource.h>
> >  #include <linux/module.h>
> >  #include <linux/interrupt.h>
> > @@ -30,6 +31,7 @@
> >  
> >  #define TMRSR 0x004
> >  #define  TMRSR_INTR_CLR BIT(30)
> > +#define  TMRSR_PCV GENMASK(28, 0)
> >  
> >  #define TMRCSSR 0x008
> >  #define  TMRCSSR_SRC_USEC (0 << 0)
> > @@ -46,6 +48,9 @@
> >  #define  WDTCR_TIMER_SOURCE_MASK 0xf
> >  #define  WDTCR_TIMER_SOURCE(x) ((x) & 0xf)
> >  
> > +#define WDTSR 0x004
> > +#define  WDTSR_CURRENT_EXPIRATION_COUNT GENMASK(14, 12)
> > +
> >  #define WDTCMDR 0x008
> >  #define  WDTCMDR_DISABLE_COUNTER BIT(1)
> >  #define  WDTCMDR_START_COUNTER BIT(0)
> > @@ -235,12 +240,69 @@ static int tegra186_wdt_set_timeout(struct watchdog_device *wdd,
> >  	return 0;
> >  }
> >  
> > +static unsigned int tegra186_wdt_get_timeleft(struct watchdog_device *wdd)
> > +{
> > +	struct tegra186_wdt *wdt = to_tegra186_wdt(wdd);
> > +	u32 expiration, val;
> > +	u64 timeleft;
> > +
> > +	if (!watchdog_active(&wdt->base)) {
> > +		/* return zero if the watchdog timer is not activated. */
> > +		return 0;
> > +	}
> > +
> > +	/*
> > +	 * Reset occurs on the fifth expiration of the
> > +	 * watchdog timer and so when the watchdog timer is configured,
> > +	 * the actual value programmed into the counter is 1/5 of the
> > +	 * timeout value. Once the counter reaches 0, expiration count
> > +	 * will be increased by 1 and the down counter restarts.
> > +	 * Hence to get the time left before system reset we must
> > +	 * combine 2 parts:
> > +	 * 1. value of the current down counter
> > +	 * 2. (number of counter expirations remaining) * (timeout/5)
> > +	 */
> > +
> > +	/* Get the current number of counter expirations. Should be a
> > +	 * value between 0 and 4
> > +	 */
> > +	val = readl_relaxed(wdt->regs + WDTSR);
> > +	expiration = FIELD_GET(WDTSR_CURRENT_EXPIRATION_COUNT, val);
> > +	if (WARN_ON_ONCE(expiration > 4))
> > +		return 0;
> > +
> > +	/* Get the current counter value in microsecond. */
> > +	val = readl_relaxed(wdt->tmr->regs + TMRSR);
> > +	timeleft = FIELD_GET(TMRSR_PCV, val);
> > +
> > +	/*
> > +	 * Calculate the time remaining by adding the time for the
> > +	 * counter value to the time of the counter expirations that
> > +	 * remain.
> > +	 */
> > +	timeleft += (((u64)wdt->base.timeout * USEC_PER_SEC) / 5) * (4 - expiration);
> 
> This results in
> 
> xtensa-linux-ld: drivers/clocksource/timer-tegra186.o: in function `tegra186_timer_remove':
> timer-tegra186.c:(.text+0x350): undefined reference to `__udivdi3'
> xtensa-linux-ld: drivers/clocksource/timer-tegra186.o: in function `tegra186_wdt_get_timeleft':
> timer-tegra186.c:(.text+0x52c): undefined reference to `__udivdi3'

I'm unable to reproduce this. I wonder if maybe I have a different
toolchain that doesn't have this issue? Do you have a link so I can try
to get closer to the setup you have?

Thanks,
Thierry

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Re: [PATCH v8 1/3] clocksource/drivers/timer-tegra186: add WDIOC_GETTIMELEFT support

[Guenter Roeck]

On 6/19/25 03:03, Thierry Reding wrote:
> On Fri, Jun 13, 2025 at 06:24:40AM -0700, Guenter Roeck wrote:
>> Hi,
>>
>> On Wed, May 07, 2025 at 12:43:09PM +0800, Robert Lin wrote:
>>> From: Pohsun Su <pohsuns@nvidia.com>
>>>
>>> This change adds support for WDIOC_GETTIMELEFT so userspace
>>> programs can get the number of seconds before system reset by
>>> the watchdog timer via ioctl.
>>>
>>> Signed-off-by: Pohsun Su <pohsuns@nvidia.com>
>>> Signed-off-by: Robert Lin <robelin@nvidia.com>
>>> ---
>>>   drivers/clocksource/timer-tegra186.c | 64 +++++++++++++++++++++++++++-
>>>   1 file changed, 63 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/clocksource/timer-tegra186.c b/drivers/clocksource/timer-tegra186.c
>>> index ea742889ee06..e3ea6110e6f5 100644
>>> --- a/drivers/clocksource/timer-tegra186.c
>>> +++ b/drivers/clocksource/timer-tegra186.c
>>> @@ -1,8 +1,9 @@
>>>   // SPDX-License-Identifier: GPL-2.0-only
>>>   /*
>>> - * Copyright (c) 2019-2020 NVIDIA Corporation. All rights reserved.
>>> + * Copyright (c) 2019-2025 NVIDIA Corporation. All rights reserved.
>>>    */
>>>   
>>> +#include <linux/bitfield.h>
>>>   #include <linux/clocksource.h>
>>>   #include <linux/module.h>
>>>   #include <linux/interrupt.h>
>>> @@ -30,6 +31,7 @@
>>>   
>>>   #define TMRSR 0x004
>>>   #define  TMRSR_INTR_CLR BIT(30)
>>> +#define  TMRSR_PCV GENMASK(28, 0)
>>>   
>>>   #define TMRCSSR 0x008
>>>   #define  TMRCSSR_SRC_USEC (0 << 0)
>>> @@ -46,6 +48,9 @@
>>>   #define  WDTCR_TIMER_SOURCE_MASK 0xf
>>>   #define  WDTCR_TIMER_SOURCE(x) ((x) & 0xf)
>>>   
>>> +#define WDTSR 0x004
>>> +#define  WDTSR_CURRENT_EXPIRATION_COUNT GENMASK(14, 12)
>>> +
>>>   #define WDTCMDR 0x008
>>>   #define  WDTCMDR_DISABLE_COUNTER BIT(1)
>>>   #define  WDTCMDR_START_COUNTER BIT(0)
>>> @@ -235,12 +240,69 @@ static int tegra186_wdt_set_timeout(struct watchdog_device *wdd,
>>>   	return 0;
>>>   }
>>>   
>>> +static unsigned int tegra186_wdt_get_timeleft(struct watchdog_device *wdd)
>>> +{
>>> +	struct tegra186_wdt *wdt = to_tegra186_wdt(wdd);
>>> +	u32 expiration, val;
>>> +	u64 timeleft;
>>> +
>>> +	if (!watchdog_active(&wdt->base)) {
>>> +		/* return zero if the watchdog timer is not activated. */
>>> +		return 0;
>>> +	}
>>> +
>>> +	/*
>>> +	 * Reset occurs on the fifth expiration of the
>>> +	 * watchdog timer and so when the watchdog timer is configured,
>>> +	 * the actual value programmed into the counter is 1/5 of the
>>> +	 * timeout value. Once the counter reaches 0, expiration count
>>> +	 * will be increased by 1 and the down counter restarts.
>>> +	 * Hence to get the time left before system reset we must
>>> +	 * combine 2 parts:
>>> +	 * 1. value of the current down counter
>>> +	 * 2. (number of counter expirations remaining) * (timeout/5)
>>> +	 */
>>> +
>>> +	/* Get the current number of counter expirations. Should be a
>>> +	 * value between 0 and 4
>>> +	 */
>>> +	val = readl_relaxed(wdt->regs + WDTSR);
>>> +	expiration = FIELD_GET(WDTSR_CURRENT_EXPIRATION_COUNT, val);
>>> +	if (WARN_ON_ONCE(expiration > 4))
>>> +		return 0;
>>> +
>>> +	/* Get the current counter value in microsecond. */
>>> +	val = readl_relaxed(wdt->tmr->regs + TMRSR);
>>> +	timeleft = FIELD_GET(TMRSR_PCV, val);
>>> +
>>> +	/*
>>> +	 * Calculate the time remaining by adding the time for the
>>> +	 * counter value to the time of the counter expirations that
>>> +	 * remain.
>>> +	 */
>>> +	timeleft += (((u64)wdt->base.timeout * USEC_PER_SEC) / 5) * (4 - expiration);
>>
>> This results in
>>
>> xtensa-linux-ld: drivers/clocksource/timer-tegra186.o: in function `tegra186_timer_remove':
>> timer-tegra186.c:(.text+0x350): undefined reference to `__udivdi3'
>> xtensa-linux-ld: drivers/clocksource/timer-tegra186.o: in function `tegra186_wdt_get_timeleft':
>> timer-tegra186.c:(.text+0x52c): undefined reference to `__udivdi3'
> 
> I'm unable to reproduce this. I wonder if maybe I have a different
> toolchain that doesn't have this issue? Do you have a link so I can try
> to get closer to the setup you have?
> 

I found that the problem is only seen with certain versions of gcc,
and only with certain architectures. I noticed it with gcc 13.3 and
13.4 when building xtensa:allmodconfig images. gcc 14.3 does not have
the problem. I did not try with other versions of gcc or clang.

Guenter