Kernel: Improve the aarch64 kernel source files disk layout

Kernel/Arch/aarch64/RPi/Timer.cpp

@@ -0,0 +1,88 @@
+/*
+ * Copyright (c) 2021, Nico Weber <thakis@chromium.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <Kernel/Arch/aarch64/MMIO.h>
+#include <Kernel/Arch/aarch64/Mailbox.h>
+#include <Kernel/Arch/aarch64/Timer.h>
+#include <Kernel/Arch/aarch64/Utils.h>
+
+namespace Prekernel {
+
+// "12.1 System Timer Registers" / "10.2 System Timer Registers"
+struct TimerRegisters {
+    u32 control_and_status;
+    u32 counter_low;
+    u32 counter_high;
+    u32 compare[4];
+};
+
+// Bits of the `control_and_status` register.
+// See "CS register" in Broadcom doc for details.
+enum FlagBits {
+    SystemTimerMatch0 = 1 << 0,
+    SystemTimerMatch1 = 1 << 1,
+    SystemTimerMatch2 = 1 << 2,
+    SystemTimerMatch3 = 1 << 3,
+};
+
+Timer::Timer()
+    : m_registers(MMIO::the().peripheral<TimerRegisters>(0x3000))
+{
+}
+
+Timer& Timer::the()
+{
+    static Timer instance;
+    return instance;
+}
+
+u64 Timer::microseconds_since_boot()
+{
+    u32 high = m_registers->counter_high;
+    u32 low = m_registers->counter_low;
+    if (high != m_registers->counter_high) {
+        high = m_registers->counter_high;
+        low = m_registers->counter_low;
+    }
+    return (static_cast<u64>(high) << 32) | low;
+}
+
+class SetClockRateMboxMessage : Prekernel::Mailbox::Message {
+public:
+    u32 clock_id;
+    u32 rate_hz;
+    u32 skip_setting_turbo;
+
+    SetClockRateMboxMessage()
+        : Prekernel::Mailbox::Message(0x0003'8002, 12)
+    {
+        clock_id = 0;
+        rate_hz = 0;
+        skip_setting_turbo = 0;
+    }
+};
+
+u32 Timer::set_clock_rate(ClockID clock_id, u32 rate_hz, bool skip_setting_turbo)
+{
+    struct __attribute__((aligned(16))) {
+        Prekernel::Mailbox::MessageHeader header;
+        SetClockRateMboxMessage set_clock_rate;
+        Prekernel::Mailbox::MessageTail tail;
+    } message_queue;
+
+    message_queue.set_clock_rate.clock_id = static_cast<u32>(clock_id);
+    message_queue.set_clock_rate.rate_hz = rate_hz;
+    message_queue.set_clock_rate.skip_setting_turbo = skip_setting_turbo ? 1 : 0;
+
+    if (!Prekernel::Mailbox::the().send_queue(&message_queue, sizeof(message_queue))) {
+        warnln("Timer::set_clock_rate() failed!");
+        return 0;
+    }
+
+    return message_queue.set_clock_rate.rate_hz;
+}
+
+}