On Thu, 2 Oct 2014, Arnd Bergmann wrote: > On Thursday 02 October 2014 01:16:46 Pavel Machek wrote: > > > > > > > > struct socfpga_reset_manager { > > > > u32 status; > > > > u32 ctrl; > > > > u32 counts; > > > > u32 padding1; > > > > u32 mpu_mod_reset; > > > > u32 per_mod_reset; > > > > u32 per2_mod_reset; > > > > u32 brg_mod_reset; > > > > }; > > > > > > > > from u-boot. Unlike macros, structs have advantages that typos lead to > > > > easier-to-see failure modes... (And they are easier to read/parse, > > > > too). > > > > > > > > > > Copying from uboot sounds good, but I already know that the CPU reset > > > offset is different for our next SOC, Arria 10. The Arria 10 SOC should > > > still be able to use the same MSL as Cyclone5 and Arria5, but with a few > > > differences. One of them being, the CPU1 reset offset is at 0x20 instead > > > of 0x10. So I think having a macro for this one register is a bit > > > cleaner than having to define a whole new struct for Arria10. > > > > I don't think "whole new struct" is a problem. At least it will be > > plain to see what changed (which will get easily lost in ifdefs. > > > > struct cyclone5_reset_manager { > > struct socfpga_reset_manager common; > > u32 brg_mod_reset; > > } > > > > struct aria10_reset_manager { > > struct socfpga_reset_manager common; > > char filler[0x10]; > > u32 brg_mod_reset; > > } > > > > if (of_machine_is_compatible("altr,socfpga-arria10")) > > __raw_writel(0, (struct cyclone5_reset_manager *) > > rst_manager_base_addr->brg_mod_reset)); > > else > > __raw_writel(0, (struct aria10_reset_manager *) > > rst_manager_base_addr->brg_mod_reset)); > > > > ...does not sound that bad. (And you'll need some nice solution for > > u-boot, anyway...) > > I think it would be better to just add more fields and access a different > field based on the SoC type than cast the structs around. > > Also, never use __raw_writel unless you know exactly what you are doing. > This should use writel, or possibly writel_relaxed.
Arnd, Pavel, I appreciate the comments. I will fix this to not be a __raw_writel. > > Finally, don't sprinkle of_machine_is_compatible() checks all over the > place. Make the decision once when you initially probe the machine. > > Arnd > The changes for aria10 are minor: a different DT plus two register changes. I'm not introducing aria10 support in this patch. This is a 16 line patch for fixing something in an established machine layer. If I have to come up with a new scheme for accessing registers, then I will need to touch other code that this patch does not intend to change. Alan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/