> Date: Fri, 8 Apr 2016 14:53:35 +0200 > From: Patrick Wildt <[email protected]> > > On Fri, Apr 08, 2016 at 03:29:05PM +0300, Artturi Alm wrote: > > On Fri, Apr 08, 2016 at 01:44:11PM +0200, Patrick Wildt wrote: > > > Hi, > > > > > > with the feedback received on the fdt bus, the fdt stuff will now be > > > replacing the mainbus. [..snip..] > > > > > > Patrick > > > > > > [..snip..] > > > > Hi, > > > > have you planned ahead which route you are going to take with regards to > > how drivers will be written in the future? i see two options, do it all > > in some kind of mainbus(per soc?) and feed driver _attach() args(i'd > > prefer), > > or infest all of the drivers with fdt node lookups and linux/fbsd-like > > code/logic. > > > > i think it's a design question that all of you should agree upon as early as > > possible to avoid cruft. as a result of my own incompetence i have rewritten > > each and every armv7 driver xxx_match() a few times. ;D > > > > -Artturi > > > > The idea is that all drivers attach to mainbus. The driver checks its > mainbus_attach_args in the match function, if the given node is > compatible to the driver, by doing something simple like: > > if (fdt_node_compatible(ma->ma_node, "samsung,exynos4210-ehci")) > return (1); > > When it attaches, it's given a node, a bus space and bus dma tag. This > is all it needs to do its job. I hope that soon we can have some > FDT-based API to attach interrupts: > > arm_intr_establish_fdt(ma->ma_node, IPL_NET, handler, sc, > sc->sc_dev.dv_xname); > > Similarly, we should have something for Clocks and GPIOs. Those are all > exposed in the device tree which we can make plenty use of. > > There are a few drivers that need special handling. EHCI and AHCI need > an attachment driver, as ehci* at mainbus? can only be handled by one > driver. So you need something like. > > imxehci* at mainbus? > ehci* at imxehci? > > That's a bit of an overhead and steals about 16 lines in > imxehci.c/imxahci.c. > > You don't anymore need an imx0, exynos0 or sunxi0 bus. Those can all be > replaced by the mainbus.
Actually, I don't think that's the right approach either. The FDT is a device tree, and the OpenBSD device tree should follow that. If you look at the device trees for the imx6 and exynos boards for example, you see that there is a "soc" node. The ehci and ahci are below that "soc" node in the device tree. You can differentiate between different SoCs based on the properties of this "soc" node, and attach different drivers based on that. Then you can have specific ahci and ehci attachments for each SoC. So you'd have: imx* at mainbus? ehci* at imx? and in your files.xxx you'd have something like: attach ehci at imx with ehci_imx file arch/armv7/imx/ehci_imx.c ehci_imx Cheers, Mark
