Rearming the riscv machine timer is done by first updating the
mtimecmp low value register. If the low value is updated with a
relatively small value, a timer interrupt can be generated while
updating the mtimecmp high value.
To avoid such a spurious interrupt to occur, disable the timer
interrupt while rearming the timer.
Change-Id: I50ab3f19554a9a8dfe70943b6da0d20be3de88dc
Signed-off-by: Jean-Paul Etienne <fractalclone@gmail.com>
Some arches may want to define this as an inline function, or
define in core arch code instead of timer driver code.
Unfortunately, this means we need to remove from the footprint
tests, but this is not typically a large function.
Issue: ZEP-1546
Change-Id: Ic0d7a33507da855995838f4703d872cd613a2ca2
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
There are race conditions trying to coordinate the value between
the accumulated_cycle_count (updated at interrupt time) and
trying to compute the delta from the last interrupt using the
mtime registers. An unlucky call could result in the timestamp
appearing to move backwards in time.
the 'mtime' register isn't reset at every interrupt. Since we just
want a cycle counter, report its raw value.
Issue: ZEP-1546
Change-Id: I9f404b33214d6502fea47374fcf0ecbf84ef8136
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
riscv defines the machine-mode timer registers that are implemented
by the all riscv SOCs that follow the riscv privileged architecture
specification.
The timer registers implemented in riscv-qemu follow this specification.
To account for future riscv SOCs, reimplement the riscv_qemu_driver by
the riscv_machine_driver.
Change-Id: I645b03c91b4e07d0f2609908decc27ba9b8240d4
Signed-off-by: Jean-Paul Etienne <fractalclone@gmail.com>
