watchdog: meson: Fix the wrong value of left time

[ Upstream commit 2c77734642d52448aca673e889b39f981110828b ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/watchdog/meson_gxbb_wdt.c b/drivers/watchdog/meson_gxbb_wdt.c
index 69a5a57f144624c6728a20d6afdcad173f243f01..61297a6ab43a00a4152cc9287fb68eec86196409 100644 (file)
--- a/drivers/watchdog/meson_gxbb_wdt.c
+++ b/drivers/watchdog/meson_gxbb_wdt.c
@@ -137,8 +137,8 @@ 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 = {