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Date: Fri, 21 Feb 2014 09:39:02 -0700
From: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
To: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Gerlando Falauto <gerlando.falauto@keymile.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
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	Gregory Cl??ment <gregory.clement@free-electrons.com>
Subject: Re: pci-mvebu driver on km_kirkwood
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On Fri, Feb 21, 2014 at 02:47:08PM +0100, Thomas Petazzoni wrote:
>  *) I don't know if the algorithm to split the BAR into multiple
>     windows is going to be trivial.

physaddr_t base,size;

while (size != 0) {
   physaddr_t window_size = 1 << log2_round_down(size);
   create_window(base,window_size);
   base += window_size;
   size -= window_size;
}

At the very worst log2_round_down is approxmiately

unsigned int log2_round_down(unsigned int val)
{
	unsigned int res = 0;
	while ((1<<res) <= val)
		res++;
	return res - 1;
}

Minimum PCI required alignment for windows is 1MB so it will always
work out into some number of mbus windows..

Jason