[PATCH 2/2] rtc: ds1685: keep setting PAB until power is removed

[Imre Kaloz <kaloz@kernel.org>]

A kickstart or wake-up flag set while its interrupt is enabled (KF with
KSE, WF with WIE) clears PAB, and the system stays powered. Clear the
event flags together with setting PAB, and repeat the write until power
is gone.

Signed-off-by: Imre Kaloz <kaloz@kernel.org>
---
 drivers/rtc/rtc-ds1685.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/rtc/rtc-ds1685.c b/drivers/rtc/rtc-ds1685.c
index 94c89333c5d5..a7828f0d6c09 100644
--- a/drivers/rtc/rtc-ds1685.c
+++ b/drivers/rtc/rtc-ds1685.c
@@ -1424,15 +1424,21 @@ ds1685_rtc_poweroff(struct platform_device *pdev)
 			rtc->write(rtc, RTC_EXT_CTRL_4B, ctrl4b);
 		}
 
-		/* Set PAB to 1 in Control 4A to power the system down. */
+		/*
+		 * Set PAB to 1 in Control 4A to power the system down.  PAB
+		 * is cleared again while KF and KSE, or WF and WIE, are set,
+		 * so keep clearing the flags and setting PAB until power is
+		 * gone.  We do not switch back to bank0.
+		 */
 		dev_warn(&pdev->dev, "Powerdown.\n");
 		msleep(20);
-		rtc->write(rtc, RTC_EXT_CTRL_4A,
-			   (ctrl4a | RTC_CTRL_4A_PAB));
-
-		/* Spin ... we do not switch back to bank0. */
-		while(1);
-		unreachable();
+		while (1) {
+			ctrl4a = rtc->read(rtc, RTC_EXT_CTRL_4A);
+			rtc->write(rtc, RTC_EXT_CTRL_4A,
+				   (ctrl4a & ~RTC_CTRL_4A_RWK_MASK) |
+				   RTC_CTRL_4A_PAB);
+			msleep(100);
+		}
 	}
 }
 EXPORT_SYMBOL_GPL(ds1685_rtc_poweroff);
-- 
2.47.3