how to best ioremap() the ranges part of a "simple-bus" device?
another (i suspect) fairly simple question, i've just never had the occasion to mess around in this part of the code. if i have a device tree source file containing the snippet: slave0: slave0-fubar@90000000 { compatible = "simple-bus"; ranges = <0x0 0x90000000 0x10000000>; #address-cells = <1>; #size-cells = <1>; }; slave1: slave1-fubar@a0000000 { compatible = "simple-bus"; ranges = <0x0 0xa0000000 0x10000000>; #address-cells = <1>; #size-cells = <1>; }; those two ranges actually represent physical addresses within an FPGA and, when certain events occur, i want some driver code to read/write some registers in slave0's address space, so obviously i'll need to access that device tree entry and effectively ioremap() slave0's physical address to a usable virtual address. is there a canonical way to do this? short of manually extracting the appropriate device tree node and reading that property and calling ioremap()? is there a wrapper for that sort of operation, which i imagine must be fairly common? oh, and a pointer to a good example in the current kernel source would, of course, be useful. rday
Thus wrote rpjday@crashcourse.ca (rpjday@crashcourse.ca):
i'll need to access that device tree entry and effectively ioremap() slave0's physical address to a usable virtual address.
is there a canonical way to do this? short of manually extracting the appropriate device tree node and reading that property and calling ioremap()? is there a wrapper for that sort of operation, which i imagine must be fairly common?
I guess that of_iomap() does what you need here.
oh, and a pointer to a good example in the current kernel source would, of course, be useful.
cm_init() in arch/arm/mach-integrator/core.c searches a dt node and does maps its address space. If you search for of_iomap() in the sources, you'll find plenty of other examples.
Thus wrote Martin Kaiser (lists@kaiser.cx):
Thus wrote rpjday@crashcourse.ca (rpjday@crashcourse.ca):
i'll need to access that device tree entry and effectively ioremap() slave0's physical address to a usable virtual address.
is there a canonical way to do this? short of manually extracting the appropriate device tree node and reading that property and calling ioremap()? is there a wrapper for that sort of operation, which i imagine must be fairly common?
I guess that of_iomap() does what you need here.
Oh, I missed your point. You were asking specifically about ranges, of_remap() searches for a reg property. I'm not aware of any generic function to parse ranges. All I found was of_pci_range_to_resource() which is specific to PCI... You could search the dt files for "ranges =", find the corresponding drivers and see how they parse the info. Sorry for the noise, Martin
participants (2)
-
Martin Kaiser -
rpjday＠crashcourse.ca