Commit 7e845ecb authored by Sui Jingfeng's avatar Sui Jingfeng Committed by Bjorn Helgaas
Browse files

PCI: Add pci_is_vga() helper 

The PCI Code and ID Assignment spec, r1.15, secs 1.4 and 1.1, define
VGA Base Class and Sub-Classes:

  03 00  PCI_CLASS_DISPLAY_VGA      VGA-compatible or 8514-compatible
  00 01  PCI_CLASS_NOT_DEFINED_VGA  VGA-compatible (before Class Code)

Add a pci_is_vga() helper to return true if a device is in either category.

These VGA devices use the hardwired legacy VGA resources
([mem 0xa0000-0xbffff], [io 0x3b0-0x3bb], [io 0x3c0-0x3df] and aliases), so
they require special handling if more than one is present in the system.

Link: https://lore.kernel.org/r/20230830111532.444535-2-sui.jingfeng@linux.dev


Signed-off-by: default avatarSui Jingfeng <suijingfeng@loongson.cn>
[bhelgaas: commit log, drop !pdev test]
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Cc: "Maciej W. Rozycki" <macro@orcam.me.uk>
parent 0bb80ecc

include/linux/pci.h

+24 −0
Original line number Diff line number Diff line
@@ -713,6 +713,30 @@ static inline bool pci_is_bridge(struct pci_dev *dev) 
		dev->hdr_type == PCI_HEADER_TYPE_CARDBUS;

}



/**

 * pci_is_vga - check if the PCI device is a VGA device

 *

 * The PCI Code and ID Assignment spec, r1.15, secs 1.4 and 1.1, define

 * VGA Base Class and Sub-Classes:

 *

 *   03 00  PCI_CLASS_DISPLAY_VGA      VGA-compatible or 8514-compatible

 *   00 01  PCI_CLASS_NOT_DEFINED_VGA  VGA-compatible (before Class Code)

 *

 * Return true if the PCI device is a VGA device and uses the legacy VGA

 * resources ([mem 0xa0000-0xbffff], [io 0x3b0-0x3bb], [io 0x3c0-0x3df] and

 * aliases).

 */

static inline bool pci_is_vga(struct pci_dev *pdev)

{

	if ((pdev->class >> 8) == PCI_CLASS_DISPLAY_VGA)

		return true;



	if ((pdev->class >> 8) == PCI_CLASS_NOT_DEFINED_VGA)

		return true;



	return false;

}



#define for_each_pci_bridge(dev, bus)				\

	list_for_each_entry(dev, &bus->devices, bus_list)	\

		if (!pci_is_bridge(dev)) {} else