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

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>

1 files changed, 10 insertions, 12 deletions

diff --git a/arch/arm/mach-ixp4xx/include/mach/io.h b/arch/arm/mach-ixp4xx/include/mach/io.h
index 0e601fe50162..6ea7e2fb2701 100644
--- a/arch/arm/mach-ixp4xx/include/mach/io.h
+++ b/arch/arm/mach-ixp4xx/include/mach/io.h
@@ -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