From f0b6eb6932e21010ae83bfcddd2d58880c4bbd19 Mon Sep 17 00:00:00 2001
From: Pankaj Raghav <dev@pankajraghav.com>
Date: Fri, 5 May 2023 14:37:26 +0200
Subject: [PATCH] Kernel: Implement helpers to manipulate MSI(x) data
 structures

MSIx table entry is used to program interrupt vectors and it is
architecture specific. Add helper functions declaration in
Arch/PCIMSI.h. The definition of the function is placed in the
respective arch specific code.
---
 Kernel/Arch/PCIMSI.h           | 42 ++++++++++++++++++++++++++++
 Kernel/Arch/x86_64/PCI/MSI.cpp | 50 ++++++++++++++++++++++++++++++++++
 Kernel/Arch/x86_64/PCI/MSI.h   | 22 +++++++++++++++
 Kernel/CMakeLists.txt          |  1 +
 4 files changed, 115 insertions(+)
 create mode 100644 Kernel/Arch/PCIMSI.h
 create mode 100644 Kernel/Arch/x86_64/PCI/MSI.cpp
 create mode 100644 Kernel/Arch/x86_64/PCI/MSI.h

diff --git a/Kernel/Arch/PCIMSI.h b/Kernel/Arch/PCIMSI.h
new file mode 100644
index 0000000000..fa5b3f4988
--- /dev/null
+++ b/Kernel/Arch/PCIMSI.h
@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2023, Pankaj R <dev@pankajraghav.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Types.h>
+
+namespace Kernel {
+#if ARCH(X86_64)
+u64 msi_address_register(u8 destination_id, bool redirection_hint, bool destination_mode);
+u32 msi_data_register(u8 vector, bool level_trigger, bool assert);
+u32 msix_vector_control_register(u32 vector_control, bool mask);
+void msi_signal_eoi();
+#elif ARCH(AARCH64)
+[[maybe_unused]] static u64 msi_address_register([[maybe_unused]] u8 destination_id, [[maybe_unused]] bool redirection_hint, [[maybe_unused]] bool destination_mode)
+{
+    TODO_AARCH64();
+    return 0;
+}
+
+[[maybe_unused]] static u32 msi_data_register([[maybe_unused]] u8 vector, [[maybe_unused]] bool level_trigger, [[maybe_unused]] bool assert)
+{
+    TODO_AARCH64();
+    return 0;
+}
+
+[[maybe_unused]] static u32 msix_vector_control_register([[maybe_unused]] u32 vector_control, [[maybe_unused]] bool mask)
+{
+    TODO_AARCH64();
+    return 0;
+}
+
+[[maybe_unused]] static void msi_signal_eoi()
+{
+    TODO_AARCH64();
+    return;
+}
+#endif
+}
diff --git a/Kernel/Arch/x86_64/PCI/MSI.cpp b/Kernel/Arch/x86_64/PCI/MSI.cpp
new file mode 100644
index 0000000000..874f9aae94
--- /dev/null
+++ b/Kernel/Arch/x86_64/PCI/MSI.cpp
@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2023, Pankaj R <dev@pankajraghav.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <Kernel/Arch/Interrupts.h>
+#include <Kernel/Arch/PCIMSI.h>
+#include <Kernel/Arch/x86_64/Interrupts/APIC.h>
+#include <Kernel/Arch/x86_64/PCI/MSI.h>
+#include <Kernel/InterruptDisabler.h>
+
+namespace Kernel {
+u64 msi_address_register(u8 destination_id, bool redirection_hint, bool destination_mode)
+{
+    u64 flags = 0;
+    if (redirection_hint) {
+        flags |= msi_redirection_hint;
+        if (destination_mode)
+            flags |= msi_destination_mode_logical;
+    }
+    return (msi_address_base | (destination_id << msi_destination_shift) | flags);
+}
+
+u32 msi_data_register(u8 vector, bool level_trigger, bool assert)
+{
+    u32 flags = 0;
+
+    if (level_trigger) {
+        flags |= msi_trigger_mode_level;
+        if (assert)
+            flags |= msi_level_assert;
+    }
+    return ((vector + IRQ_VECTOR_BASE) & msi_data_vector_mask) | flags;
+}
+
+u32 msix_vector_control_register(u32 vector_control, bool mask)
+{
+    if (!mask)
+        return (vector_control & msi_vector_control_unmask);
+    return (vector_control | msi_vector_control_mask);
+}
+
+void msi_signal_eoi()
+{
+    InterruptDisabler disabler;
+    APIC::the().eoi();
+}
+
+}
diff --git a/Kernel/Arch/x86_64/PCI/MSI.h b/Kernel/Arch/x86_64/PCI/MSI.h
new file mode 100644
index 0000000000..efe38c2888
--- /dev/null
+++ b/Kernel/Arch/x86_64/PCI/MSI.h
@@ -0,0 +1,22 @@
+/*
+ * Copyright (c) 2023, Pankaj R <dev@pankajraghav.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+// Address register
+static constexpr u32 msi_address_base = 0xfee00000;
+static constexpr u8 msi_destination_shift = 12;
+static constexpr u32 msi_redirection_hint = 0x00000008;
+static constexpr u32 msi_destination_mode_logical = 0x00000004;
+
+// Data register
+static constexpr u8 msi_data_vector_mask = 0xff;
+static constexpr u32 msi_trigger_mode_level = 0x00008000;
+static constexpr u32 msi_level_assert = 0x00004000;
+
+// Vector control
+static constexpr u32 msi_vector_control_mask = 0x1;
+static constexpr u32 msi_vector_control_unmask = ~(0x1);
diff --git a/Kernel/CMakeLists.txt b/Kernel/CMakeLists.txt
index 54d7ae41ef..067fe7f63f 100644
--- a/Kernel/CMakeLists.txt
+++ b/Kernel/CMakeLists.txt
@@ -393,6 +393,7 @@ if ("${SERENITY_ARCH}" STREQUAL "x86_64")
         Arch/x86_64/PCI/Controller/HostBridge.cpp
         Arch/x86_64/PCI/IDELegacyModeController.cpp
         Arch/x86_64/PCI/Initializer.cpp
+        Arch/x86_64/PCI/MSI.cpp
 
         Arch/x86_64/VGA/IOArbiter.cpp