From ea104a9e4d3e9ebc26fb78dac35585b142ee288b Mon Sep 17 00:00:00 2001
From: Michael Walle <michael@walle.cc>
Date: Fri, 27 Mar 2020 17:24:50 +0100
Subject: [PATCH] watchdog: sp805: fix restart handler
Git-commit: ea104a9e4d3e9ebc26fb78dac35585b142ee288b
Patch-mainline: v5.7-rc2
References: bsc#1111666

The restart handler is missing two things, first, the registers
has to be unlocked and second there is no synchronization for the
write_relaxed() calls.

This was tested on a custom board with the NXP LS1028A SoC.

Fixes: 6c5c0d48b686c ("watchdog: sp805: add restart handler")
Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20200327162450.28506-1-michael@walle.cc
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/watchdog/sp805_wdt.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/watchdog/sp805_wdt.c b/drivers/watchdog/sp805_wdt.c
index 53e04926a7b2..190d26e2e75f 100644
--- a/drivers/watchdog/sp805_wdt.c
+++ b/drivers/watchdog/sp805_wdt.c
@@ -137,10 +137,14 @@ wdt_restart(struct watchdog_device *wdd, unsigned long mode, void *cmd)
 {
 	struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
 
+	writel_relaxed(UNLOCK, wdt->base + WDTLOCK);
 	writel_relaxed(0, wdt->base + WDTCONTROL);
 	writel_relaxed(0, wdt->base + WDTLOAD);
 	writel_relaxed(INT_ENABLE | RESET_ENABLE, wdt->base + WDTCONTROL);
 
+	/* Flush posted writes. */
+	readl_relaxed(wdt->base + WDTLOCK);
+
 	return 0;
 }
 
-- 
2.16.4