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Kernel/PCI: Fix support of multiple PCI host controllers enumeration

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First scan PCI bus 0. Find any device on that bus, and if it's a
PCI-to-PCI bridge, recursively scan it too.

Then try to handle Multiple PCI host bridges on slot 0, device 0.
If we happen to miss some PCI buses because they are not reachable
through recursive PCI-to-PCI bridges scanning starting from bus 0, we
might find them in this scanning.
This commit is contained in:
Liav A 2021-05-21 12:06:20 +03:00 • committed by Linus Groh
parent c6ffee7f18
commit 07474b4349
3 changed files with 24 additions and 11 deletions
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29
Kernel/PCI/IOAccess.cpp
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@ -67,17 +67,26 @@ void IOAccess::write32_field(Address address, u32 field, u32 value)
void IOAccess::enumerate_hardware(Function<void(Address, ID)> callback)
{
dbgln_if(PCI_DEBUG, "PCI: IO enumerating hardware");
// Single PCI host controller.
if ((read8_field(Address(), PCI_HEADER_TYPE) & 0x80) == 0) {
enumerate_bus(-1, 0, callback, true);
return;
}
// Multiple PCI host controllers.
for (int bus = 0; bus < 256; ++bus) {
if (read16_field(Address(0, 0, 0, bus), PCI_VENDOR_ID) == PCI_NONE)
break;
enumerate_bus(-1, bus, callback, false);
// First scan bus 0. Find any device on that bus, and if it's a PCI-to-PCI
// bridge, recursively scan it too.
m_enumerated_buses.set(0, true);
enumerate_bus(-1, 0, callback, true);
// Handle Multiple PCI host bridges on slot 0, device 0.
// If we happen to miss some PCI buses because they are not reachable through
// recursive PCI-to-PCI bridges starting from bus 0, we might find them here.
if ((read8_field(Address(), PCI_HEADER_TYPE) & 0x80) != 0) {
for (int bus = 1; bus < 256; ++bus) {
if (read16_field(Address(0, 0, 0, bus), PCI_VENDOR_ID) == PCI_NONE)
continue;
if (read16_field(Address(0, 0, 0, bus), PCI_CLASS) != 0x6)
continue;
if (m_enumerated_buses.get(bus))
continue;
enumerate_bus(-1, bus, callback, false);
m_enumerated_buses.set(bus, true);
}
}
}