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From 2c77734642d52448aca673e889b39f981110828b Mon Sep 17 00:00:00 2001
From: Xingyu Chen <xingyu.chen@amlogic.com>
Date: Sun, 29 Sep 2019 18:53:49 +0800
Subject: [PATCH] watchdog: meson: Fix the wrong value of left time
Git-commit: 2c77734642d52448aca673e889b39f981110828b
Patch-mainline: v5.4-rc7
References: bsc#1051510

The left time value is wrong when we get it by sysfs. The left time value
should be equal to preset timeout value minus elapsed time value. According
to the Meson-GXB/GXL datasheets which can be found at [0], the timeout value
is saved to BIT[0-15] of the WATCHDOG_TCNT, and elapsed time value is saved
to BIT[16-31] of the WATCHDOG_TCNT.

[0]: http://linux-meson.com

Fixes: 683fa50f0e18 ("watchdog: Add Meson GXBB Watchdog Driver")
Signed-off-by: Xingyu Chen <xingyu.chen@amlogic.com>
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
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/meson_gxbb_wdt.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/watchdog/meson_gxbb_wdt.c b/drivers/watchdog/meson_gxbb_wdt.c
index d17c1a6ed723..5a9ca10fbcfa 100644
--- a/drivers/watchdog/meson_gxbb_wdt.c
+++ b/drivers/watchdog/meson_gxbb_wdt.c
@@ -89,8 +89,8 @@ static unsigned int meson_gxbb_wdt_get_timeleft(struct watchdog_device *wdt_dev)
 
 	reg = readl(data->reg_base + GXBB_WDT_TCNT_REG);
 
-	return ((reg >> GXBB_WDT_TCNT_CNT_SHIFT) -
-		(reg & GXBB_WDT_TCNT_SETUP_MASK)) / 1000;
+	return ((reg & GXBB_WDT_TCNT_SETUP_MASK) -
+		(reg >> GXBB_WDT_TCNT_CNT_SHIFT)) / 1000;
 }
 
 static const struct watchdog_ops meson_gxbb_wdt_ops = {
-- 
2.16.4