[U-Boot] in/out_le32, etc.

[U-Boot] in/out_le32, etc.

[Aaron Williams]

One thing that is getting confusing to me is that there seems to be many 
different methods for doing I/O.

There's in_xxx/out_xxx, __raw_readx/__raw_writex and readx/writex.  What 
exactly is the difference between all of these?  It looks like the in/out was 
added recently and is not present in the mips io.h file.

In a related case, I run into problems with a number of drivers because they 
assume that readl/writel can be used to access the PCI BAR address space or 
that a pointer is a physical address. This is not always the case.

For example, on our platform the PCI BAR address space is mapped to different 
64-bit address spaces depending on the bus number. It would be very helpful if 
different macros were used for different I/O devices. For example, one set of 
macros for accessing PCI BAR address space.

-Aaron

[U-Boot] in/out_le32, etc.

[Shinya Kuribayashi]

On 02/12/2011 08:23 PM, Aaron Williams wrote:
> There's in_xxx/out_xxx, __raw_readx/__raw_writex and readx/writex.  What 
> exactly is the difference between all of these?  It looks like the in/out was 
> added recently and is not present in the mips io.h file.

In the MIPS code, 'mips_io_port_base' makes in_xxx/out_xxx distinct
from readx/writex.  And raw operations are never swapped in software.
Check <asm/io.h> for more details.

> For example, on our platform the PCI BAR address space is mapped to different 
> 64-bit address spaces depending on the bus number. It would be very helpful if 
> different macros were used for different I/O devices. For example, one set of 
> macros for accessing PCI BAR address space.