The current mips clock build infrastructure lets a system only use
either the MIPS cp0 counter or a SoC specific timer as a clocksource /
clockevent device.
This patch renames the core cp0 counter clocksource / clockevent functions
from mips_* to r4k_* and updates the wrappers in asm-mips/time.h to
call these renamed functions instead.
Chips which can detect whether it is safe to use a chip-specific timer
can now fall back on the cp0 counter if necessary and possible
(e.g. Alchemy with a follow-on patch).
Existing behaviour is not changed in any way.
Signed-off-by: Manuel Lauss <mano@roarinelk.homelinux.net>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Impact: change calling convention of existing clock_event APIs
struct clock_event_timer's cpumask field gets changed to take pointer,
as does the ->broadcast function.
Another single-patch change. For safety, we BUG_ON() in
clockevents_register_device() if it's not set.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@elte.hu>
Rework of SMTC support to make it work with the new clock event system,
allowing "tickless" operation, and to make it compatible with the use of
the "wait_irqoff" idle loop. The new clocking scheme means that the
previously optional IPI instant replay mechanism is now required, and has
been made more robust.
Signed-off-by: Kevin D. Kissell <kevink@paralogos.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
The R4000 and R4400 have an errata where if the cp0 count register is read
in the exact moment when it matches the compare register no interrupt will
be generated.
This bug may be triggered if the cp0 count register is being used as
clocksource and the compare interrupt as clockevent. So a simple
workaround is to avoid using the compare for both facilities on the
affected CPUs.
This is different from the workaround suggested in the old errata documents;
at some opportunity probably the official version should be implemented
and tested. Another thing to find out is which processor versions
exactly are affected. I only have errata documents upto R4400 V3.0
available so for the moment the code treats all R4000 and R4400 as broken.
This is potencially a problem for some machines that have no other decent
clocksource available; this workaround will cause them to fall back to
another clocksource, worst case the "jiffies" source.
Try increasingly longer time periods starting of at 0x10 cycles. This
should be fast on hardware and work nicely with emulators.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
The expression "(long)(read_c0_count() - cnt)" can never be a negative
value on 64-bit kernel. Cast to "int" before comparison.
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
