HI Prabhu, On Tue, Jul 10, 2012 at 2:00 AM, Prabhu nath <gprabhunath@xxxxxxxxx> wrote: > Thanks for your reply. Plz see inline > > On Tue, Jul 10, 2012 at 11:50 AM, Dave Hylands <dhylands@xxxxxxxxx> wrote: >> >> Hi Prabhu, >> >> On Mon, Jul 9, 2012 at 9:56 PM, Prabhu nath <gprabhunath@xxxxxxxxx> wrote: >> > Dear All, >> > >> > Is it possible to map a physical address of a device >> > to a >> > known Kernel virtual address. I know about ioremap_xxx (...). >> > which will map a physical address of a device to a kernel virtual >> > address >> > allocated by ioremap_xxx(...). >> > >> > For E.g. I have a device whose physical address range is 0x80008000 to >> > 0x80008FFF. >> > Is it possible to map this device physical address to a >> > known >> > virtual address range 0xF0008000 to 0xF0008FFF. >> >> About the only way to do this is to use static mappings. I was under >> the impression that static mappings are on the way out, and that >> dynamic mappings are required when using device tree. >> >> An example of using static mappings can be found here: >> >> http://lxr.linux.no/linux+v3.4.4/arch/arm/mach-integrator/integrator_ap.c#L88 > > > In this file, how did they mark IO_BASE. Is the allocator not aware of > this region in the kernel virtual address space. ? Well for a given device it's really kind of arbitrary. For the integrator device IO_BASE is found here: http://lxr.linux.no/linux+v3.4.4/arch/arm/mach-integrator/include/mach/hardware.h#L31 Nornally you would make sure that the I/O area doesn't overlap with the vmalloc area by controlling VMALLOC_END. But since the default VMALLOC_END is now 0xff000000 it looks like they're trying to make you use dynamic mappings. -- Dave Hylands Shuswap, BC, Canada http://www.davehylands.com _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
