linux-kernel - [PATCH] watchdog: sp805: fix restart handler

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Date:   Fri, 27 Mar 2020 17:24:50 +0100
From:   Michael Walle <michael@...le.cc>
To:     linux-kernel@...r.kernel.org, linux-watchdog@...r.kernel.org
Cc:     Jongsung Kim <neidhard.kim@....com>,
        Guenter Roeck <linux@...ck-us.net>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Michael Walle <michael@...le.cc>
Subject: [PATCH] watchdog: sp805: fix restart handler

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@...le.cc>
---
 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;
 }
 
-- 
2.20.1