On 20/02/2018 14:33, Andy Shevchenko wrote:

On Mon, Feb 19, 2018 at 7:48 PM, John Garry [off-list ref] wrote:

quoted

From: Zhichang Yuan <redacted>

In commit 41f8bba7f555 ("of/pci: Add pci_register_io_range() and
pci_pio_to_address()"), a new I/O space management was supported. With
that driver, the I/O ranges configured for PCI/PCIe hosts on some
architectures can be mapped to logical PIO, converted easily between
CPU address and the corresponding logicial PIO. Based on this, PCI
I/O devices can be accessed in a memory read/write way through the
unified in/out accessors.

But on some archs/platforms, there are bus hosts which access I/O
peripherals with host-local I/O port addresses rather than memory
addresses after memory-mapped.

To support those devices, a more generic I/O mapping method is introduced
here. Through this patch, both the CPU addresses and the host-local port
can be mapped into the logical PIO space with different logical/fake PIOs.
After this, all the I/O accesses to either PCI MMIO devices or host-local
I/O peripherals can be unified into the existing I/O accessors defined in
asm-generic/io.h and be redirected to the right device-specific hooks
based on the input logical PIO.

Hi Andy,

quoted

+#define PIO_INDIRECT           0x01UL /* indirect IO flag */
+#define PIO_CPU_MMIO           0x00UL /* memory mapped io flag */

It looks like bitfield, but from use I don't see it.

IIRC, the orignal intention was that this would be a bit value in a 
bitfield.

Perhaps use enum instead?

I'll change to enum to be clear.

quoted

+       resource_size_t hwaddr = -1;

quoted

+unsigned long
+               return -1;
+               return -1;

quoted

+unsigned long
+       return -1;

quoted

+type logic_in##bw(unsigned long addr)                                  \
+       type ret = -1;                                                  \

All types above are unsigned. I'm not sure it's the best approach to
use -1 implicitly casted to unsigned type.

I would rather use ~0UL or alike.

Yes, I can change these.

Much appreciated,
John