On Fri, Jun 18, 2010 at 10:25 PM, Lorenzo Pieralisi <lorenzo.pieral...@arm.com> wrote: > Concerning platform_devices ids, sorry I wasn't meant to report an amba > primecell binding snippet, I wanted to report here just a > binding for a simple memory mapped platform device (not a primecell one). I > was asking that question about platform_device > statically defined structs that use the id for enumeration, and going with > FDT the id has to be initialized somehow from the tree > because the struct is allocated dynamically. > > Wrt map_desc point taken, I was looking into possible ways of getting rid of > platform specific statically defined data, that array > in particular. >
That's actually quite challenging. And as DT is used to 'describe' the hardware as is, instead of directing the software how to do a mapping, I doubt this should be done with DT. > Thanks a lot for your feedback, > > Lorenzo > > -----Original Message----- > From: Russell King - ARM Linux [mailto:li...@arm.linux.org.uk] > Sent: Friday, June 18, 2010 2:13 PM > To: Lorenzo Pieralisi > Cc: 'Grant Likely'; devicetree-discuss; linux-arm-ker...@lists.infradead.org; > Jeremy Kerr; Nicolas Pitre > Subject: Re: Platform data with function pointers > > On Fri, Jun 18, 2010 at 01:47:28PM +0100, Lorenzo Pieralisi wrote: >> I think chip-select addressing should be used if that is the way HW handles >> it. If the device is described through a > memory-mapping, >> ex. snippet follows: >> >> ser...@101f2000 { >> compatible = "arm,pl011"; >> reg = <0x101f2000 0x1000 >; >> }; > > Primecell devices aren't platform devices. They have no 'id' field as > such. Instead, modern implementations have PCI-like IDs. > >> struct map_desc { >> unsigned long virtual; >> unsigned long pfn; >> unsigned long length; >> unsigned int type; >> }; >> >> static struct map_desc realview_eb_io_desc[] __initdata = { >> { >> .virtual = IO_ADDRESS(REALVIEW_SYS_BASE), >> .pfn = __phys_to_pfn(REALVIEW_SYS_BASE), >> .length = SZ_4K, >> .type = MT_DEVICE, >> }, ... > > These mappings are entirely arbitary, and change according to the > implementation of the platform. > > Some platforms want to avoid using ioremap() to create 4K page mappings > for their devices, so instead they statically map them and arrange for > ioremap() to know about that static mapping. > > Given that PAGE_OFFSET can be changed, it would be absolutely silly to > put this into the device tree. > > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-ker...@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > _______________________________________________ devicetree-discuss mailing list devicetree-discuss@lists.ozlabs.org https://lists.ozlabs.org/listinfo/devicetree-discuss
