Commit 9f8010e7 authored by Thomas Bogendoerfer's avatar Thomas Bogendoerfer Committed by Alexandre Belloni
Browse files

rtc: ds1685: Fix bank switching to avoid endless loop 



ds1685_rtc_begin_data_access() tried to access an extended register before
enabling access to it by switching to bank 1. Depending on content in NVRAM
this could lead to an endless loop. While at it fix also switch back to
bank 0 in ds1685_rtc_end_data_access().

Signed-off-by: default avatarThomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@bootlin.com>
Acked-by: default avatarJoshua Kinard <kumba@gentoo.org>
Link: https://lore.kernel.org/r/20200910084124.138560-1-tsbogend@alpha.franken.de
parent d0a3b650

drivers/rtc/rtc-ds1685.c

+4 −4
Original line number Diff line number Diff line
@@ -193,12 +193,12 @@ ds1685_rtc_begin_data_access(struct ds1685_priv *rtc) 
	rtc->write(rtc, RTC_CTRL_B,

		   (rtc->read(rtc, RTC_CTRL_B) | RTC_CTRL_B_SET));



	/* Switch to Bank 1 */

	ds1685_rtc_switch_to_bank1(rtc);



	/* Read Ext Ctrl 4A and check the INCR bit to avoid a lockout. */

	while (rtc->read(rtc, RTC_EXT_CTRL_4A) & RTC_CTRL_4A_INCR)

		cpu_relax();



	/* Switch to Bank 1 */

	ds1685_rtc_switch_to_bank1(rtc);

}



/**
@@ -213,7 +213,7 @@ static inline void 
ds1685_rtc_end_data_access(struct ds1685_priv *rtc)

{

	/* Switch back to Bank 0 */

	ds1685_rtc_switch_to_bank1(rtc);

	ds1685_rtc_switch_to_bank0(rtc);



	/* Clear the SET bit in Ctrl B */

	rtc->write(rtc, RTC_CTRL_B,