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Commit ac5ad93e authored by Gavin Shan's avatar Gavin Shan Committed by Bjorn Helgaas
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PCI: Add weak pcibios_window_alignment() interface 



This patch implements a weak function to return the default I/O or memory
window alignment for a P2P bridge.  By default, I/O windows are aligned to
4KiB or 1KiB and memory windows are aligned to 4MiB.  Some platforms, e.g.,
powernv, have special alignment requirements and can override
pcibios_window_alignment().

[bhelgaas: changelog]
Signed-off-by: default avatarGavin Shan <shangw@linux.vnet.ibm.com>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
parent 479e0d48

drivers/pci/setup-bus.c

+32 −0
Original line number Diff line number Diff line
@@ -697,6 +697,38 @@ static resource_size_t calculate_memsize(resource_size_t size, 
	return size;

}



resource_size_t __weak pcibios_window_alignment(struct pci_bus *bus,

						unsigned long type)

{

	return 1;

}



#define PCI_P2P_DEFAULT_MEM_ALIGN	0x100000	/* 1MiB */

#define PCI_P2P_DEFAULT_IO_ALIGN	0x1000		/* 4KiB */

#define PCI_P2P_DEFAULT_IO_ALIGN_1K	0x400		/* 1KiB */



static resource_size_t window_alignment(struct pci_bus *bus,

					unsigned long type)

{

	resource_size_t align = 1, arch_align;



	if (type & IORESOURCE_MEM)

		align = PCI_P2P_DEFAULT_MEM_ALIGN;

	else if (type & IORESOURCE_IO) {

		/*

		 * Per spec, I/O windows are 4K-aligned, but some

		 * bridges have an extension to support 1K alignment.

		 */

		if (bus->self->io_window_1k)

			align = PCI_P2P_DEFAULT_IO_ALIGN_1K;

		else

			align = PCI_P2P_DEFAULT_IO_ALIGN;

	}



	arch_align = pcibios_window_alignment(bus, type);

	return max(align, arch_align);

}



/**

 * pbus_size_io() - size the io window of a given bus

 *

include/linux/pci.h

+2 −0
Original line number Diff line number Diff line
@@ -1064,6 +1064,8 @@ int pci_cfg_space_size_ext(struct pci_dev *dev); 
int pci_cfg_space_size(struct pci_dev *dev);

unsigned char pci_bus_max_busnr(struct pci_bus *bus);

void pci_setup_bridge(struct pci_bus *bus);

resource_size_t pcibios_window_alignment(struct pci_bus *bus,

					 unsigned long type);



#define PCI_VGA_STATE_CHANGE_BRIDGE (1 << 0)

#define PCI_VGA_STATE_CHANGE_DECODES (1 << 1)