From aab55360fa11a2c054798a484ac67ad606f563e4 Mon Sep 17 00:00:00 2001 From: James Hilliard Date: Thu, 27 Aug 2026 22:42:31 -0600 Subject: [PATCH] watchdog: sunxi_wdt: preserve boot-enabled watchdog sunxi_wdt_probe() unconditionally stops the watchdog even when firmware left it running. This opens an unprotected interval during boot and prevents CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED from taking over the active watchdog. Detect an enabled watchdog and decode its programmed interval. Preserve representable timeouts, and round the 0.5-second interval up to the minimum representable one-second timeout. Use the configured timeout for reserved interval encodings. Set the Linux reset mode and ping the watchdog without clearing its enable bit, then mark it hardware-running before registration so the watchdog core services it until userspace takes control. Leave disabled watchdogs untouched. Fixes: d00680ed0026 ("watchdog: sunxi: New watchdog driver for Allwinner A10/A13") Cc: stable@vger.kernel.org Signed-off-by: James Hilliard Link: https://patch.msgid.link/20260827-submit-sunxi-wdt-boot-enabled-v1-v2-1-610d37dccc97@gmail.com Signed-off-by: Guenter Roeck --- drivers/watchdog/sunxi_wdt.c | 45 +++++++++++++++++++++++++++++++++++- 1 file changed, 44 insertions(+), 1 deletion(-) diff --git a/drivers/watchdog/sunxi_wdt.c b/drivers/watchdog/sunxi_wdt.c index b6c761acc3de..3db34524ed13 100644 --- a/drivers/watchdog/sunxi_wdt.c +++ b/drivers/watchdog/sunxi_wdt.c @@ -128,6 +128,38 @@ static int sunxi_wdt_ping(struct watchdog_device *wdt_dev) return 0; } +static bool sunxi_wdt_is_running(struct watchdog_device *wdt_dev) +{ + struct sunxi_wdt_dev *sunxi_wdt = watchdog_get_drvdata(wdt_dev); + const struct sunxi_wdt_reg *regs = sunxi_wdt->wdt_regs; + + return readl(sunxi_wdt->wdt_base + regs->wdt_mode) & WDT_MODE_EN; +} + +static unsigned int sunxi_wdt_get_timeout(struct watchdog_device *wdt_dev) +{ + struct sunxi_wdt_dev *sunxi_wdt = watchdog_get_drvdata(wdt_dev); + const struct sunxi_wdt_reg *regs = sunxi_wdt->wdt_regs; + unsigned int timeout; + u32 interval; + + interval = readl(sunxi_wdt->wdt_base + regs->wdt_mode); + interval >>= regs->wdt_timeout_shift; + interval &= WDT_TIMEOUT_MASK; + /* Round the 0.5-second interval up to the minimum representable timeout. */ + if (!interval) + return WDT_MIN_TIMEOUT; + + for (timeout = WDT_MIN_TIMEOUT; + timeout < ARRAY_SIZE(wdt_timeout_map); timeout++) { + if (wdt_timeout_map[timeout] == interval) + return timeout; + } + + /* Reserved interval encoding. */ + return 0; +} + static int sunxi_wdt_set_timeout(struct watchdog_device *wdt_dev, unsigned int timeout) { @@ -259,6 +291,7 @@ static int sunxi_wdt_probe(struct platform_device *pdev) { struct device *dev = &pdev->dev; struct sunxi_wdt_dev *sunxi_wdt; + unsigned int running_timeout; int err; sunxi_wdt = devm_kzalloc(dev, sizeof(*sunxi_wdt), GFP_KERNEL); @@ -286,7 +319,17 @@ static int sunxi_wdt_probe(struct platform_device *pdev) watchdog_set_drvdata(&sunxi_wdt->wdt_dev, sunxi_wdt); - sunxi_wdt_stop(&sunxi_wdt->wdt_dev); + if (sunxi_wdt_is_running(&sunxi_wdt->wdt_dev)) { + running_timeout = sunxi_wdt_get_timeout(&sunxi_wdt->wdt_dev); + if (running_timeout) + sunxi_wdt->wdt_dev.timeout = running_timeout; + + err = sunxi_wdt_start(&sunxi_wdt->wdt_dev); + if (err) + return err; + + set_bit(WDOG_HW_RUNNING, &sunxi_wdt->wdt_dev.status); + } watchdog_stop_on_reboot(&sunxi_wdt->wdt_dev); err = devm_watchdog_register_device(dev, &sunxi_wdt->wdt_dev);