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| author | Nicolas Ferre <nicolas.ferre@atmel.com> | 2013-03-22 15:04:47 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-03-22 16:41:20 -0700 |
| commit | 0ef1594c017521ea89278e80fe3f80dafb17abde (patch) | |
| tree | 2a35cc7a32cb03acf30e1e977ec1a010fa40b876 /drivers/rtc/rtc-at91rm9200.h | |
| parent | e66b05873a7a76afc569da6382509471cba8d5ff (diff) | |
| download | linux-0ef1594c017521ea89278e80fe3f80dafb17abde.tar.gz linux-0ef1594c017521ea89278e80fe3f80dafb17abde.tar.bz2 linux-0ef1594c017521ea89278e80fe3f80dafb17abde.zip | |
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 <nicolas.ferre@atmel.com>
Reported-by: Douglas Gilbert <dgilbert@interlog.com>
Cc: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Cc: Ludovic Desroches <ludovic.desroches@atmel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/rtc/rtc-at91rm9200.h')
| -rw-r--r-- | drivers/rtc/rtc-at91rm9200.h | 1 |
1 files changed, 0 insertions, 1 deletions
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 */ |