Hi Vlad, On 20 December 2016 at 08:53, Vlad Zakharov <[email protected]> wrote: > Hi everybody, > > I am working on reorganization of device trees for ARC boards in U-Boot in > order to create a common device tree blob for > both Linux and U-Boot. > > And I've struggled with a kind of problem and need some help. > > On AXS10x motherboard clocks for various peripherals are managed by one > hardware block, so clock nodes in Linux device > tree are grouped into one "clocks" node like this: > ---------------------------------->8------------------------------------ > clocks { > i2cclk: i2cclk { > compatible = "fixed-clock"; > clock-frequency = <50000000>; > #clock-cells = <0>; > }; > ... > ... > ... > uartclk: uartclk { > compatible = "fixed-clock"; > clock-frequency = <33333333>; > #clock-cells = <0>; > }; > }; > ---------------------------------->8------------------------------------ > And then some of them a referenced via phandle from other nodes, e.g. > &uartclk is referenced from uart node. > > When I try to create such hierarchy in U-Boot I find that uart driver is not > able to get clock via phandle and > corresponding uart doesn't work. > > As I understand that is because children clocks nodes, i.e. "uartclk" in my > case, never got bound as it's parent node > "clocks" never got bound too. > So when I add "compatible" and "u-boot,dm-pre-reloc" properties to "clocks" > parent node everything works fine, e.g.: > ---------------------------------->8------------------------------------ > clocks { > compatible = "simple-bus"; > u-boot,dm-pre-reloc; > uartclk: uartclk { > compatible = "fixed-clock"; > > clock-frequency = <33333333>; > #clock-cells = <0>; > }; > ... > ... > ... > }; > ---------------------------------->8------------------------------------ > > Please correct me if I wrongly interpret such behavior. > > I wonder if it the only approach to implement Linux-like hierarchy for ARC? > Or I am mistaken and in fact can use pure > Linux device tree without adding properties, described above?
Yes you have it right. I'm not sure what linux is doing here - does it look for a node called 'clocks'? To my mind, U-Boot is the more correct. Regards, Simon _______________________________________________ U-Boot mailing list [email protected] http://lists.denx.de/mailman/listinfo/u-boot
