rtc: stmp3xxx: Don't reset the rtc in .probe() when watchdog is running

Message ID 20180609064313.18763-1-u.kleine-koenig@pengutronix.de
State New
Headers show
Series
  • rtc: stmp3xxx: Don't reset the rtc in .probe() when watchdog is running
Related show

Commit Message

Uwe Kleine-König June 9, 2018, 6:43 a.m.
As pointed out in the added comment resetting the rtc also stops the
included watchdog. This is bad if the bootloader started the watchdog to
secure the boot process. So don't reset if the watchdog is running.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 drivers/rtc/rtc-stmp3xxx.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

Patch

diff --git a/drivers/rtc/rtc-stmp3xxx.c b/drivers/rtc/rtc-stmp3xxx.c
index d578e40d5a50..b76318fd5bb0 100644
--- a/drivers/rtc/rtc-stmp3xxx.c
+++ b/drivers/rtc/rtc-stmp3xxx.c
@@ -288,10 +288,22 @@  static int stmp3xxx_rtc_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, rtc_data);
 
-	err = stmp_reset_block(rtc_data->io);
-	if (err) {
-		dev_err(&pdev->dev, "stmp_reset_block failed: %d\n", err);
-		return err;
+	/*
+	 * Resetting the rtc stops the watchdog timer that is potentially
+	 * running. So (assuming it is running on purpose) don't reset if the
+	 * watchdog is enabled.
+	 */
+	if (readl(rtc_data->io + STMP3XXX_RTC_CTRL) &
+	    STMP3XXX_RTC_CTRL_WATCHDOGEN) {
+		dev_info(&pdev->dev,
+			 "Watchdog is running, skip resetting rtc\n");
+	} else {
+		err = stmp_reset_block(rtc_data->io);
+		if (err) {
+			dev_err(&pdev->dev, "stmp_reset_block failed: %d\n",
+				err);
+			return err;
+		}
 	}
 
 	/*