Commit 2856ba60 authored by Jon Derrick's avatar Jon Derrick Committed by Bjorn Helgaas
Browse files

PCI: Introduce pci_real_dma_dev() 

The current DMA alias implementation requires the aliased device be on the
same PCI bus as the requester ID.  Add an arch-specific mechanism to point
to another PCI device when doing mapping and PCI DMA alias search.  The
default case returns the actual device.

Link: https://lore.kernel.org/r/1579613871-301529-4-git-send-email-jonathan.derrick@intel.com


Signed-off-by: default avatarJon Derrick <jonathan.derrick@intel.com>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Cc: Christoph Hellwig <hch@lst.de>
parent 34067c56

arch/x86/pci/common.c

+10 −0
Original line number Diff line number Diff line
@@ -736,3 +736,13 @@ int pci_ext_cfg_avail(void) 
	else

		return 0;

}



#if IS_ENABLED(CONFIG_VMD)

struct pci_dev *pci_real_dma_dev(struct pci_dev *dev)

{

	if (is_vmd(dev->bus))

		return to_pci_sysdata(dev->bus)->vmd_dev;



	return dev;

}

#endif

drivers/pci/pci.c

+18 −1
Original line number Diff line number Diff line
@@ -6033,7 +6033,9 @@ bool pci_devs_are_dma_aliases(struct pci_dev *dev1, struct pci_dev *dev2) 
	return (dev1->dma_alias_mask &&

		test_bit(dev2->devfn, dev1->dma_alias_mask)) ||

	       (dev2->dma_alias_mask &&

		test_bit(dev1->devfn, dev2->dma_alias_mask));

		test_bit(dev1->devfn, dev2->dma_alias_mask)) ||

	       pci_real_dma_dev(dev1) == dev2 ||

	       pci_real_dma_dev(dev2) == dev1;

}



bool pci_device_is_present(struct pci_dev *pdev)
@@ -6057,6 +6059,21 @@ void pci_ignore_hotplug(struct pci_dev *dev) 
}

EXPORT_SYMBOL_GPL(pci_ignore_hotplug);



/**

 * pci_real_dma_dev - Get PCI DMA device for PCI device

 * @dev: the PCI device that may have a PCI DMA alias

 *

 * Permits the platform to provide architecture-specific functionality to

 * devices needing to alias DMA to another PCI device on another PCI bus. If

 * the PCI device is on the same bus, it is recommended to use

 * pci_add_dma_alias(). This is the default implementation. Architecture

 * implementations can override this.

 */

struct pci_dev __weak *pci_real_dma_dev(struct pci_dev *dev)

{

	return dev;

}



resource_size_t __weak pcibios_default_alignment(void)

{

	return 0;

drivers/pci/search.c

+6 −0
Original line number Diff line number Diff line
@@ -32,6 +32,12 @@ int pci_for_each_dma_alias(struct pci_dev *pdev, 
	struct pci_bus *bus;

	int ret;



	/*

	 * The device may have an explicit alias requester ID for DMA where the

	 * requester is on another PCI bus.

	 */

	pdev = pci_real_dma_dev(pdev);



	ret = fn(pdev, pci_dev_id(pdev), data);

	if (ret)

		return ret;

include/linux/pci.h

+1 −0
Original line number Diff line number Diff line
@@ -1202,6 +1202,7 @@ int __must_check pci_resize_resource(struct pci_dev *dev, int i, int size); 
int pci_select_bars(struct pci_dev *dev, unsigned long flags);

bool pci_device_is_present(struct pci_dev *pdev);

void pci_ignore_hotplug(struct pci_dev *dev);

struct pci_dev *pci_real_dma_dev(struct pci_dev *dev);



int __printf(6, 7) pci_request_irq(struct pci_dev *dev, unsigned int nr,

		irq_handler_t handler, irq_handler_t thread_fn, void *dev_id,

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