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Date:      Wed, 15 Jul 2020 19:34:19 +0000 (UTC)
From:      Adrian Chadd <adrian@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r363236 - head/sys/mips/atheros
Message-ID:  <202007151934.06FJYJFg049663@repo.freebsd.org>
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Author: adrian
Date: Wed Jul 15 19:34:19 2020
New Revision: 363236
URL: https://svnweb.freebsd.org/changeset/base/363236

Log:
  [ar71xx] fix watchdog to work on subsequent SoCs
  
  The AR9341 AHB runs at 225MHz, much faster than the 33MHz of the
  AR71xx AHB.  So not only is the math going to do weird things, it
  will also wrap rather than being clamped.
  
  So:
  
  * clamp! don't wrap!
  * tidy up some debugging
  * add an option to throw an NMI rather than reset!
  
  Tested:
  
  * AR9341 SoC (TP-Link TL-WDR4300), patting/not patting the watchdog!

Modified:
  head/sys/mips/atheros/ar71xx_wdog.c

Modified: head/sys/mips/atheros/ar71xx_wdog.c
==============================================================================
--- head/sys/mips/atheros/ar71xx_wdog.c	Wed Jul 15 18:49:00 2020	(r363235)
+++ head/sys/mips/atheros/ar71xx_wdog.c	Wed Jul 15 19:34:19 2020	(r363236)
@@ -50,6 +50,7 @@ struct ar71xx_wdog_softc {
 	device_t dev;
 	int armed;
 	int reboot_from_watchdog;
+	int watchdog_nmi;
 	int debug;
 };
 
@@ -58,32 +59,54 @@ ar71xx_wdog_watchdog_fn(void *private, u_int cmd, int 
 {
 	struct ar71xx_wdog_softc *sc = private;
 	uint64_t timer_val;
+	int action;
 
+	action = RST_WDOG_ACTION_RESET;
+	if (sc->watchdog_nmi != 0)
+		action = RST_WDOG_ACTION_NMI;
+
 	cmd &= WD_INTERVAL;
 	if (sc->debug)
-		device_printf(sc->dev, "ar71xx_wdog_watchdog_fn: cmd: %x\n", cmd);
+		device_printf(sc->dev, "%s: : cmd: %x\n", __func__, cmd);
 	if (cmd > 0) {
 		timer_val = (uint64_t)(1ULL << cmd) * ar71xx_ahb_freq() /
 		    1000000000;
+
+		/*
+		 * Clamp the timer value in case we overflow.
+		 */
+		if (timer_val > 0xffffffff)
+			timer_val = 0xffffffff;
 		if (sc->debug)
-			device_printf(sc->dev, "ar71xx_wdog_watchdog_fn: programming timer: %jx\n", (uintmax_t) timer_val);
+			device_printf(sc->dev, "%s: programming timer: %jx\n",
+			    __func__, (uintmax_t) timer_val);
 		/*
-		 * Load timer with large enough value to prevent spurious
-		 * reset
+		 * Make sure the watchdog is set to NOACTION and give it
+		 * time to take.
 		 */
-		ATH_WRITE_REG(AR71XX_RST_WDOG_TIMER, 
-		    ar71xx_ahb_freq() * 10);
-		ATH_WRITE_REG(AR71XX_RST_WDOG_CONTROL, 
-		    RST_WDOG_ACTION_RESET);
-		ATH_WRITE_REG(AR71XX_RST_WDOG_TIMER, 
-		    (timer_val & 0xffffffff));
+		ATH_WRITE_REG(AR71XX_RST_WDOG_CONTROL, RST_WDOG_ACTION_NOACTION);
+		wmb();
+		DELAY(100);
+
+		/*
+		 * Update the timer value.  It's already clamped at this
+		 * point so we don't have to wrap/clamp it here.
+		 */
+		ATH_WRITE_REG(AR71XX_RST_WDOG_TIMER, timer_val);
+		wmb();
+		DELAY(100);
+
+		/*
+		 * And now, arm.
+		 */
+		ATH_WRITE_REG(AR71XX_RST_WDOG_CONTROL, action);
 		sc->armed = 1;
 		*error = 0;
 	} else {
 		if (sc->debug)
-			device_printf(sc->dev, "ar71xx_wdog_watchdog_fn: disarming\n");
+			device_printf(sc->dev, "%s: disarming\n", __func__);
 		if (sc->armed) {
-			ATH_WRITE_REG(AR71XX_RST_WDOG_CONTROL, 
+			ATH_WRITE_REG(AR71XX_RST_WDOG_CONTROL,
 			    RST_WDOG_ACTION_NOACTION);
 			sc->armed = 0;
 		}
@@ -109,6 +132,9 @@ ar71xx_wdog_sysctl(device_t dev)
         SYSCTL_ADD_INT(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
                 "debug", CTLFLAG_RW, &sc->debug, 0,
                 "enable watchdog debugging");
+        SYSCTL_ADD_INT(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
+                "nmi", CTLFLAG_RW, &sc->watchdog_nmi, 0,
+                "watchdog triggers NMI instead of reset");
         SYSCTL_ADD_INT(ctx, SYSCTL_CHILDREN(tree), OID_AUTO,
                 "armed", CTLFLAG_RD, &sc->armed, 0,
                 "whether the watchdog is armed");

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