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IXP4xx: Extend PCI MMIO indirect address space to 1 GB.

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IXP4xx CPUs can indirectly access the whole 4 GB PCI MMIO address space (using
the non-prefetch registers). Previously the available space depended on the CPU
variant, since one of the IXP43x platforms needed more than the usual 128 MB.
1 GB should be enough for everyone, and if not, we can trivially increase it.

Signed-off-by: Krzysztof Hałasa <khc@pm.waw.pl>
This commit is contained in:
Krzysztof Hałasa
2009-11-15 18:02:10 +01:00
parent cba362221b
commit ed5b9fa0d1
4 changed files with 29 additions and 29 deletions
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22
arch/arm/mach-ixp4xx/include/mach/io.h
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@@ -26,22 +26,20 @@ extern int ixp4xx_pci_write(u32 addr, u32 cmd, u32 data);
/*
* IXP4xx provides two methods of accessing PCI memory space:
*
* 1) A direct mapped window from 0x48000000 to 0x4bffffff (64MB).
* 1) A direct mapped window from 0x48000000 to 0x4BFFFFFF (64MB).
* To access PCI via this space, we simply ioremap() the BAR
* into the kernel and we can use the standard read[bwl]/write[bwl]
* macros. This is the preffered method due to speed but it
* limits the system to just 64MB of PCI memory. This can be
* problamatic if using video cards and other memory-heavy
* targets.
*
* 2) If > 64MB of memory space is required, the IXP4xx can be configured
* to use indirect registers to access PCI (as we do below for I/O
* transactions). This allows for up to 128MB (0x48000000 to 0x4fffffff)
* of memory on the bus. The disadvantage of this is that every
* PCI access requires three local register accesses plus a spinlock,
* but in some cases the performance hit is acceptable. In addition,
* you cannot mmap() PCI devices in this case.
* limits the system to just 64MB of PCI memory. This can be
* problematic if using video cards and other memory-heavy targets.
*
* 2) If > 64MB of memory space is required, the IXP4xx can use indirect
* registers to access the whole 4 GB of PCI memory space (as we do below
* for I/O transactions). This allows currently for up to 1 GB (0x10000000
* to 0x4FFFFFFF) of memory on the bus. The disadvantage of this is that
* every PCI access requires three local register accesses plus a spinlock,
* but in some cases the performance hit is acceptable. In addition, you
* cannot mmap() PCI devices in this case.
*/
#ifndef CONFIG_IXP4XX_INDIRECT_PCI