On 13 May 2015 at 00:31, Stephen Boyd <sboyd@xxxxxxxxxxxxxx> wrote: > On 04/27, Joachim Eastwood wrote: >> This patch set adds support for the two main clock peripherals in the >> LPC18xx/43xx MCU family. >> >> The Clock Generation Unit (CGU) is the base source of all clocks. It has >> five external inputs and contains PLLs, dividers and muxes. The outputs >> from the CGU are then routed to a Clock Control Unit (CCU) and a few >> peripherals directly. There are two CCUs in the MCU. The CCU is a >> collection of gates and a few dividers that sits between the CGU and >> most of the peripherals. >> >> Which clocks that are available depends on the specific device and it's >> peripherals. It's possible in DT to setup the routing between the CGU >> and the CCUs. > > Is there any reason why this uses CLK_OF_DECLARE over the > platform device model? Typically we have CLK_OF_DECLARE for cases > where a provider needs to be up and running early during boot for > hardware that can't probe defer (i.e. timers, irq controllers). One of the CCUs provided clock for two of the timers that are used as clock sources. Specifically this timer: http://marc.info/?l=linux-arm-kernel&m=143138193704763&w=2 Since the CGU provides the clock to the CCU which then again provides the clock to the timer both must use CLK_OF_DECLARE for clk enable/get rate to work in the timer driver. > Otherwise we should be able to use the standard linux device > model to probe clk providers. It looks like the clocksource is > using something from CCU, but perhaps CGU isn't "special" and > could be using device model. It's is the CCU that uses the clocks from the CGU. So I think both drivers needs to use CLK_OF_DECLARE. regards, Joachim Eastwood -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
