apx needs to set compare b due to errata of XTAL glitch
ap4p needs to set minimum delta to 4
err026 requires XTAL to not be switched off/on when resetting
Signed-off-by: Richard Wheatley <richard.wheatley@ambiq.com>
The original driver has two defects: 1. When setting the next timeout
value the original implementation simply sets a delta value equal to
ticks * CYC_PER_TICK. This operation is reckless and may incorrectly
"reset" the fractional tick, causing clock skew. 2. The original
implementation doesn't handle the counter overflow situation. When the
counter overflows from 0xffffffff to 0x0, the uptimer counter becomes
incorrect. We have fixed above issue by rewriting most of the functions in
this driver and verified it by running all tests under
tests/kernel/timer folder.
Signed-off-by: Zhengwei Wang <zwang@ambiq.com>
In sys_clock_set_timeout(), input "ticks" is used to compute next
timeout point, Ambiq's STimer API used to sets next timeout has input
parameter as ui32Delta, which inside the API is using
"this value to add to the STimer counter and load into the comparator
register" according to its spec, thus the this delta clock is
almost equivalent to input "ticks"'s concept, and is not related to
last_count, it should be computed directly from input "ticks".
This correction fixes the test case failure at
zephyr\tests\kernel\tickless\tickless_concept.
Signed-off-by: Bryan Zhu <bzhu@ambiq.com>
In init function, start timer with period CYC_PER_TICK if tickless is
not enabled, This change is for fixing the issue that disabling
CONFIG_TICKLESS_KERNEL the OS tick is not work issue, this
causes the OS not starting scheduling correctly.
Signed-off-by: Bryan Zhu <bzhu@ambiq.com>
This commit addst support for the system timer peripheral which
can be found in Apollo4 SoCs.
Signed-off-by: Maciej Sobkowski <msobkowski@antmicro.com>
