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All rights reserved. > + * Copyright (c) 2019-2025 NVIDIA Corporation. All rights reserved. > */ > > +#include > #include > #include > #include > @@ -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 +240,63 @@ 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 timeleft, expiration, val; > + > + 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(expiration > 4)) > + return 0; > + > + /* Get the current counter value in microsecond. > + */ > + val = readl_relaxed(wdt->tmr->regs + TMRSR); > + timeleft = FIELD_GET(TMRSR_PCV, val); So this value is in microseconds. > + > + /* > + * Calculate the time remaining by adding the time for the > + * counter value to the time of the counter expirations that > + * remain. Do the multiplication first on purpose just to keep > + * the precision due to the integer division. > + */ > + timeleft += wdt->base.timeout * (4 - expiration) / 5; However, wdt->base.timeout is in seconds. So I don't think we can simply add this. Don't we need to ... timeleft += (wdt->base.timeout * USEC_PER_SEC * (4 - expiration)) / 5; Given that this could be quite a big number, we probably want to make timeleft a 64-bit type too. So we may want to define a 'u64 timeleft_usecs' and 'u32 timeleft_secs' that we return. Jon -- nvpublic