From 0ef1594c017521ea89278e80fe3f80dafb17abde Mon Sep 17 00:00:00 2001 From: Nicolas Ferre Date: Fri, 22 Mar 2013 15:04:47 -0700 Subject: drivers/rtc/rtc-at91rm9200.c: use a variable for storing IMR On some revisions of AT91 SoCs, the RTC IMR register is not working. Instead of elaborating a workaround for that specific SoC or IP version, we simply use a software variable to store the Interrupt Mask Register and modify it for each enabling/disabling of an interrupt. The overhead of this is negligible anyway. The interrupt mask register (IMR) for the RTC is broken on the AT91SAM9x5 sub-family of SoCs (good overview of the members here: http://www.eewiki.net/display/linuxonarm/AT91SAM9x5 ). The "user visible effect" is the RTC doesn't work. That sub-family is less than two years old and only has devicetree (DT) support and came online circa lk 3.7 . The dust is yet to settle on the DT stuff at least for AT91 SoCs (translation: lots of stuff is still broken, so much that it is hard to know where to start). The fix in the patch is pretty simple: just shadow the silicon IMR register with a variable in the driver. Some older SoCs (pre-DT) use the the rtc-at91rm9200 driver (e.g. obviously the AT91RM9200) and they should not be impacted by the change. There shouldn't be a large volume of interrupts associated with a RTC. Signed-off-by: Nicolas Ferre Reported-by: Douglas Gilbert Cc: Jean-Christophe PLAGNIOL-VILLARD Cc: Ludovic Desroches Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/rtc/rtc-at91rm9200.h | 1 - 1 file changed, 1 deletion(-) (limited to 'drivers/rtc/rtc-at91rm9200.h') diff --git a/drivers/rtc/rtc-at91rm9200.h b/drivers/rtc/rtc-at91rm9200.h index da1945e5f714..5f940b6844cb 100644 --- a/drivers/rtc/rtc-at91rm9200.h +++ b/drivers/rtc/rtc-at91rm9200.h @@ -64,7 +64,6 @@ #define AT91_RTC_SCCR 0x1c /* Status Clear Command Register */ #define AT91_RTC_IER 0x20 /* Interrupt Enable Register */ #define AT91_RTC_IDR 0x24 /* Interrupt Disable Register */ -#define AT91_RTC_IMR 0x28 /* Interrupt Mask Register */ #define AT91_RTC_VER 0x2c /* Valid Entry Register */ #define AT91_RTC_NVTIM (1 << 0) /* Non valid Time */ -- cgit v1.2.3