32-bit driver with 64-bit device PIO

[Priya Suryanarayanan]

I am developing a 32-bit device driver on a 32-bit OS. The device has a
combination of 32-bit registers and 64-bit-wide device buffer. This is a
PCI Express system, Intel CPU. I have a couple of questions.

I know that my PIOs result in 32-bit reads and writes when I use readl()
and writel(). This takes care of only the 32-bit registers on the
device. For the 64-bit-wide device memory buffer, are there any APIs
which make it possible to address them?

On a slightly unrelated note, and speaking of a 32-bit system & device,
how does the PCI Express Root Complex prepare Mem Write TLPs? Does each
memory write access by the driver result in a single TLP with 1 DWORD of
data? This seems inefficient. Suppose I write to consecutive locations,
does the Root Complex generate a single Mem Write TLP with multiple
DWORDS of data?

Thanks in advance for any inputs.
Regards,
- priya

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