rtc: ds1307: provide an indication that the watchdog has fired

There's not much feedback when the ds1388 watchdog fires. Generally it
yanks on the reset line and the board reboots. Capture the fact that the
watchdog has fired in the past so that userspace can retrieve it via
WDIOC_GETBOOTSTATUS. This should help distinguish a watchdog triggered
reset from a power interruption.

Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20200727034615.19755-1-chris.packham@alliedtelesis.co.nz

diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index 49702942bb086229e592244b5ad9328eba06fe67..54c85cdd019dda2b3dcf43f6144d10259598c80d 100644 (file)
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -1668,6 +1668,8 @@ static const struct watchdog_ops ds1388_wdt_ops = {
 static void ds1307_wdt_register(struct ds1307 *ds1307)
 {
        struct watchdog_device  *wdt;
+       int err;
+       int val;
 
        if (ds1307->type != ds_1388)
                return;
@@ -1676,6 +1678,10 @@ static void ds1307_wdt_register(struct ds1307 *ds1307)
        if (!wdt)
                return;
 
+       err = regmap_read(ds1307->regmap, DS1388_REG_FLAG, &val);
+       if (!err && val & DS1388_BIT_WF)
+               wdt->bootstatus = WDIOF_CARDRESET;
+
        wdt->info = &ds1388_wdt_info;
        wdt->ops = &ds1388_wdt_ops;
        wdt->timeout = 99;