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Kernel/PCI: Introduce a new ECAM access mechanism

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Now the kernel supports 2 ECAM access methods.
MMIOAccess was renamed to WindowedMMIOAccess and is what we had until
now - each device that is detected on boot is assigned to a
memory-mapped window, so IO operations on multiple devices can occur
simultaneously due to creating multiple virtual mappings, hence the name
is a memory-mapped window.

This commit adds a new class called MMIOAccess (not to be confused with
the old MMIOAccess class). This class creates one memory-mapped window.
On each IO operation on a configuration space of a device, it maps the
requested PCI bus region to that window. Therefore it holds a SpinLock
during the operation to ensure that no other PCI bus region was mapped
during the call.

A user can choose to either use PCI ECAM with memory-mapped window
for each device, or for an entire bus. By default, the kernel prefers to
map the entire PCI bus region.
This commit is contained in:
Liav A 2021-04-03 16:46:04 +03:00 • committed by Andreas Kling
parent 441e374396
commit 8abbb7e090
11 changed files with 320 additions and 100 deletions
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28
Kernel/PCI/Initializer.cpp
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@ -30,6 +30,7 @@
#include <Kernel/PCI/IOAccess.h>
#include <Kernel/PCI/Initializer.h>
#include <Kernel/PCI/MMIOAccess.h>
#include <Kernel/PCI/WindowedMMIOAccess.h>
#include <Kernel/Panic.h>
namespace Kernel {
@ -37,25 +38,38 @@ namespace PCI {
static bool test_pci_io();
UNMAP_AFTER_INIT static Access::Type detect_optimal_access_type(bool mmio_allowed)
UNMAP_AFTER_INIT static PCIAccessLevel detect_optimal_access_type(PCIAccessLevel boot_determined)
{
if (mmio_allowed && ACPI::is_enabled() && !ACPI::Parser::the()->find_table("MCFG").is_null())
return Access::Type::MMIO;
if (!ACPI::is_enabled() || ACPI::Parser::the()->find_table("MCFG").is_null())
return PCIAccessLevel::IOAddressing;
if (boot_determined != PCIAccessLevel::IOAddressing)
return boot_determined;
if (test_pci_io())
return Access::Type::IO;
return PCIAccessLevel::IOAddressing;
PANIC("No PCI bus access method detected!");
}
UNMAP_AFTER_INIT void initialize()
{
bool mmio_allowed = kernel_command_line().is_pci_ecam_enabled();
auto boot_determined = kernel_command_line().pci_access_level();
if (detect_optimal_access_type(mmio_allowed) == Access::Type::MMIO)
switch (detect_optimal_access_type(boot_determined)) {
case PCIAccessLevel::MappingPerDevice:
WindowedMMIOAccess::initialize(ACPI::Parser::the()->find_table("MCFG"));
break;
case PCIAccessLevel::MappingPerBus:
MMIOAccess::initialize(ACPI::Parser::the()->find_table("MCFG"));
else
break;
case PCIAccessLevel::IOAddressing:
IOAccess::initialize();
break;
default:
VERIFY_NOT_REACHED();
}
PCI::enumerate([&](const Address& address, ID id) {
dmesgln("{} {}", address, id);
});