Hummm.. I see. For the tickless implementation with 2 timers it's interesting to have the <chip>_oneshot.c to help implement the System Interfaces along with the <chip>_freerun.c. The 2 timers approach is intended to keep one timer to track time and the another to drive the events? What would be the hardware timer requirements to implement the first approach? Is the first approach preferable only because it saves more hardware resources or is there something else?
Em ter., 16 de mar. de 2021 às 14:49, Gregory Nutt <spudan...@gmail.com> escreveu: > Most architectures support a timer library. The <chip>_oneshot.c file > is a wrapper around the library that creates an internal one shot > driver. That oneshot does not depend on the onshot driver and can be > used anywhere in the OS architecture-specific code where you need a > oneshot. The <chip>_lowerhalf.c file is another wrapper around the > oneshot implementation that implements the lower half of the oneshot > character driver that is used only by applications. So those are > different things: One is for the OS and one is for applications. > > That file structure also used to support the tickless mode. Tickless > mode may be implemented in one of either two ways: With one or two > timers. See https://cwiki.apache.org/confluence/display/NUTTX/Tickless+OS > > When tickless mode is implemented with a single timer, it is usually in > a file called <chip>_tickless.c. when it is implemented with two > timers, it is usually implemented in three files: <chip>_freerun.c, > <chip>_oneshot.c, and <chip>_tickless.c. If the hardware can support > the single timer tickless solution, that is a better way to go. In most > cases, the two timer implementations have been converted to one timer > implementations but these two file remain in the directories for the > free-running and oneshot timers, but are otherwise not used for tickless > mode by the OS. > > On 3/16/2021 11:12 AM, Sara da Cunha Monteiro de Souza wrote: > > Hi all, > > > > I've been working on the oneshot driver implementation for ESP32 > and > > I've noticed that other chips split the implementation into 2 files: > > > > - <chip>_oneshot_lowerhalf.c > > - <chip>_oneshot.c > > > > The second file is not used at all besides the lowerhalf. And the > > lowerhalf file seems more like a wrapper for the API that is > > in <chip>_oneshot.c. > > > > That stated, is it fine if I keep only the lowerhalf file? > > Why the <chip>_oneshot.c was created in the other implementations > > instead of only keeping everything on the lowerhalf file? > > > > Thanks in advance for reading it. > > My best regards, > > > > Sara > > > >
