On Thu, 2006-06-29 at 00:37 +0200, Guennadi Liakhovetski wrote: > On Tue, 27 Jun 2006, Johannes Berg wrote: > > > You may want to hold off working on this a bit and first ask BenH for > > his old patches that converted the pmu stuff to the generic thing but > > needed invasive generic stuff first. > > Well, I started thinking about possible solutions for mpc824x by looking > at the only available sleep implementation for ppc in the kernel - > powermac. As was suggested I looked under drivers/macintosh. As an example > I took powerbook_sleep_grackle() (I think, grackle is also installed in > "blue and white" G3's, right?). There I see various calls to pmu_request() > with macros as parameters and some comments, so, most things can be > understood and mapped to another hardware (if still relevant under the new > power-management interface). But then come some things that I don't > understand: > > /* Ask the PMU to put us to sleep */ > pmu_request(&req, NULL, 5, PMU_SLEEP, 'M', 'A', 'T', 'T'); > > So, what exactly does this command do? It sends a command to the PMU microcontroller to go to sleep. The result depends on the machine model (I'd suggest you look at the core99 version rather than the grackle version, it's more sane, and the B&W G3 doesn't have a PMU anyway). On anything recent, the PMU will then wait for a signal from the northbridge indicating that the processor entered an idle state (NAP or SLEEP), and when that haappens, will shut down various bits of the motherboard, including the CPU, stop some clocks etc... so basically put the machine to sleep (and do the thing with the LED). It will also control the wakeup signals from the USB or the button (or the ADB keyboard) and reboot the CPU when that hapens. > Next I'll dig the real low-level stuff > > low_sleep_handler(); > > I am already excited about getting my hands dirty with ppc assembly:-) The above flushes all processor caches (since the CPU is going to be powered down) and saves as much as necessary of the CPU state, then put the CPU into a SLEEP loop waiting for the shutdown by the PMU. It also sets up some magic vectors where the ROM code will jump to on resume and restores everything it saved. > Thanks > Guennadi > --- > Guennadi Liakhovetski
