what's a platform device?

From: Kumar Gala
Date: Wed Feb 22 2006 - 16:55:36 EST


Guys,

I was hoping to get your opinion on a question I had. The question comes
down to what we think a "platform device" is.

The situation I have is an FPGA connected over PCI. The FPGA implements
various device functionality (serial ports, I2C controller, IR, etc.) as a
single PCI device/function. The FPGA breaks any notion of a true PCI
device, it uses PCI as a device interconnect more than anything else.

In talking to Greg about this, he suggested I just create a new bus_type
for this similar to what is being done for usb-serial. As I started to
think about what I wanted ended up being a platform_device plus a sysfs
entry for the MMIO region.

So, it seems that a "platform device" is a pretty generic concept now. Do
you guys thing its acceptable to use a platform device for my needs or
should I create some new bus_type? Do we have a better definition of what
a platform device is or might be?

If we're ok with my use of platform device for this, I assume no one has
an issue with adding a sysfs attribute to platform devices to expose the
MMIO regions similar to what we do for PCI today.

thanks

- kumar

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