From 7e845ecb2fbfa1bf800e703df29ee2e06592c2a0 Mon Sep 17 00:00:00 2001
From: Sui Jingfeng <suijingfeng@loongson.cn>
Date: Wed, 30 Aug 2023 19:15:28 +0800
Subject: 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: Sui Jingfeng <suijingfeng@loongson.cn>
[bhelgaas: commit log, drop !pdev test]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: "Maciej W. Rozycki" <macro@orcam.me.uk>
---
include/linux/pci.h | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 8c7c2c3c6c65..7bab234391cb 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -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
--
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