From: Ranjani Vaidyanathan Date: Fri, 6 Feb 2026 00:23:32 +0000 (+0800) Subject: watchdog: imx7ulp_wdt: Keep WDOG running until A55 enters WFI on i.MX94 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=1f5b29add64e7c1500530079bbbe359cad28cb63;p=thirdparty%2Fkernel%2Flinux.git watchdog: imx7ulp_wdt: Keep WDOG running until A55 enters WFI on i.MX94 On i.MX94, watchdog sources clock from bus clock that will be always on during the lifecycle of Linux. There is a Low Power Clock Gating(LPCG) between the bus clock and watchdog, but the LPCG is not exported for software to control, it is hardware automatically controlled. When Cortex-A55 executes WFI during suspend flow, the LPCG will automatically gate off the clock to stop watchdog and resume clock when Cortex-A55 is woke up. So watchdog could always be alive to protect Linux, except Cortex-A platform WFI is executed in Linux suspend flow. Introduce a new hardware feature flag to indicate CPU low-power-mode auto clock gating support, and use it to avoid stopping the watchdog during suspend when LPCG can safely keep it running. Add i.MX94-specific watchdog hardware data and DT compatible entry to enable this behavior. Signed-off-by: Ranjani Vaidyanathan [peng.fan@nxp.com: rewrite commit log for clarity] Signed-off-by: Peng Fan Reviewed-by: Guenter Roeck Reviewed-by: Frank Li Link: https://lore.kernel.org/r/20260206-imx94-wdog-v2-1-4dd725faec1f@nxp.com Signed-off-by: Guenter Roeck --- diff --git a/drivers/watchdog/imx7ulp_wdt.c b/drivers/watchdog/imx7ulp_wdt.c index 03479110453ce..855dc9d5083a5 100644 --- a/drivers/watchdog/imx7ulp_wdt.c +++ b/drivers/watchdog/imx7ulp_wdt.c @@ -56,6 +56,7 @@ MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" struct imx_wdt_hw_feature { bool prescaler_enable; bool post_rcs_wait; + bool cpu_lpm_auto_cg; u32 wdog_clock_rate; }; @@ -360,7 +361,7 @@ static int __maybe_unused imx7ulp_wdt_suspend_noirq(struct device *dev) { struct imx7ulp_wdt_device *imx7ulp_wdt = dev_get_drvdata(dev); - if (watchdog_active(&imx7ulp_wdt->wdd)) + if (watchdog_active(&imx7ulp_wdt->wdd) && !imx7ulp_wdt->hw->cpu_lpm_auto_cg) imx7ulp_wdt_stop(&imx7ulp_wdt->wdd); clk_disable_unprepare(imx7ulp_wdt->clk); @@ -408,10 +409,17 @@ static const struct imx_wdt_hw_feature imx93_wdt_hw = { .wdog_clock_rate = 125, }; +static const struct imx_wdt_hw_feature imx94_wdt_hw = { + .prescaler_enable = true, + .wdog_clock_rate = 125, + .cpu_lpm_auto_cg = true, +}; + static const struct of_device_id imx7ulp_wdt_dt_ids[] = { { .compatible = "fsl,imx7ulp-wdt", .data = &imx7ulp_wdt_hw, }, { .compatible = "fsl,imx8ulp-wdt", .data = &imx8ulp_wdt_hw, }, { .compatible = "fsl,imx93-wdt", .data = &imx93_wdt_hw, }, + { .compatible = "fsl,imx94-wdt", .data = &imx94_wdt_hw, }, { /* sentinel */ } }; MODULE_DEVICE_TABLE(of, imx7ulp_wdt_dt_ids);