Hi Michel, On Tue, Apr 10, 2018 at 11:56 AM, Michel Pollet <michel.pollet@xxxxxxxxxxxxxx> wrote: > In the current SDK for the RZ/N1, we made a clock architecture that is entirely device-tree based. > The clock hierarchy is quite complex and was machine generated from design documents, and > some exceptions and grouping were added to the 'main' family rzn1.dtsi... > > Apart from a few fixed-clock nodes, all of the other nodes are 'special' and require a driver. All > of these drivers are sub-drivers to a 'main' clock driver. That has been working for 2 years already. > > One extra note: we don't 'own' all of these clocks, part of the clocks/dividers can be > enable/disabled by the CM3 core. > > Now, For upstreaming, I'm going to have to change that, since already the 'clock' bits are going > to go under the MFD sysctrl node. However I'm trying to figure out if we can still use our > rzn1-clocks.dtsi in some form, as well as my drivers, or so I have to convert it to a C table in > some way. > > Also note that all the clock refer to SYSCTRL registers/bits using constant names from a header > file, not hex constants etc. > > I would appreciate any ideas/suggestions before I commit blindly to a path... > > Here is the main autogenerated clock file: > https://github.com/renesas-rz/rzn1_linux/blob/rzn1-stable/arch/arm/boot/dts/rzn1-clocks.dtsi > Here's the extra clock{} node in the main rzn1.dtsi > https://github.com/renesas-rz/rzn1_linux/blob/89d6c9be056a462b95d5217221d70d6e5c25dfc2/arch/arm/boot/dts/rzn1.dtsi#L70 Describing the full clock hierarchy in DT is no longer recommended. The modern way is to have a single clock provider node in DT, and have the driver register all clocks. Compare e.g. the single clock-controller node in arch/arm/boot/dts/r8a7791.dtsi in v4.15 (used with the {r8a7791,renesas}-cpg-mssr.c driver, with the complex clocks node in v4.14, used with a lot of subdrivers, and requiring continuous maintenance. So I think you're best of creating (generating) a C table instead, and keep the DT simple and obviously correct. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
