kernel/amd64: Add Local APIC driver

This commit introduces the initial Local APIC driver sources

Signed-off-by: sigsegv7 <ian@vegaa.systems>

2 files changed, 169 insertions, 0 deletions

diff --git a/sys/arch/amd64/lapic.c b/sys/arch/amd64/lapic.c
new file mode 100644
index 0000000..6a5ed9a
--- /dev/null
+++ b/sys/arch/amd64/lapic.c
@@ -0,0 +1,167 @@
+/*
+ * Copyright (c) 2023 Ian Marco Moffett and the VegaOS team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of VegaOS nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <machine/lapic.h>
+#include <machine/lapicvar.h>
+#include <machine/cpuid.h>
+#include <machine/msr.h>
+#include <sys/types.h>
+#include <sys/cdefs.h>
+#include <sys/syslog.h>
+#include <sys/panic.h>
+#include <sys/mmio.h>
+
+/*
+ * Only calls KINFO if we are the BSP.
+ */
+#define BSP_KINFO(...)                      \
+    uint64_t msr_val;                       \
+                                            \
+    msr_val = rdmsr(IA32_APIC_BASE_MSR);    \
+    if (__TEST(msr_val, 1 << 8)) {          \
+        KINFO(__VA_ARGS__);                 \
+    }
+
+__MODULE_NAME("lapic");
+__KERNEL_META("$Vega$: lapic.c, Ian Marco Moffett, "
+              "Local APIC driver");
+
+static void *lapic_base = NULL;
+
+/*
+ * Returns true if LAPIC is supported.
+ *
+ * LAPIC is supported if CPUID.(EAX=1H):EDX[9] == 1
+ */
+static inline bool
+lapic_check_support(void)
+{
+    uint32_t eax, edx, tmp;
+
+    __CPUID(0x00000001, eax, tmp, tmp, edx);
+    return __TEST(edx, 1 << 9);
+}
+
+/*
+ * Reads a 32 bit value from Local APIC
+ * register space.
+ *
+ * @reg: Register to read from.
+ */
+static inline uint32_t
+lapic_readl(uint32_t reg)
+{
+    void *addr;
+
+    addr = (void *)((uintptr_t)lapic_base + reg);
+    return mmio_read32(addr);
+}
+
+/*
+ * Writes a 32 bit value to Local APIC
+ * register space.
+ *
+ * @reg: Register to write to.
+ */
+static inline void
+lapic_writel(uint32_t reg, uint32_t val)
+{
+    void *addr;
+
+    addr = (void *)((uintptr_t)lapic_base + reg);
+    mmio_write32(addr, val);
+}
+
+/*
+ * Set bits within a LAPIC register
+ * without overwriting the whole thing.
+ *
+ * @reg: Reg with bits to be set.
+ * @value: Value in reg will be ORd with this.
+ */
+static inline void
+lapic_reg_set(uint32_t reg, uint32_t value)
+{
+    uint32_t old;
+
+    old = lapic_readl(reg);
+    lapic_writel(reg, old | value);
+}
+
+/*
+ * Clear bits within a LAPIC register
+ * without overwriting the whole thing.
+ *
+ * @reg: Reg with bits to be cleared.
+ * @value: Value in reg will be cleared by this value.
+ */
+static inline void
+lapic_reg_clear(uint32_t reg, uint32_t value)
+{
+    uint32_t old;
+
+    old = lapic_readl(reg);
+    lapic_writel(reg, old & ~(value));
+}
+
+void
+lapic_set_base(void *mmio_base)
+{
+    if (lapic_base == NULL)
+        lapic_base = mmio_base;
+}
+
+void
+lapic_init(void)
+{
+    uint64_t tmp;
+
+    /* Sanity check */
+    if (lapic_base == NULL) {
+        panic("LAPIC base not set!\n");
+    }
+
+    if (!lapic_check_support()) {
+        /*
+         * VegaOS currently depends on the existance
+         * of a Local APIC.
+         */
+        panic("This machine does not support LAPIC!\n");
+    }
+
+    /* Hardware enable the Local APIC */
+    tmp = rdmsr(IA32_APIC_BASE_MSR);
+    wrmsr(IA32_APIC_BASE_MSR, tmp | LAPIC_HW_ENABLE);
+
+    /* Software enable the Local APIC via SVR */
+    lapic_reg_set(LAPIC_SVR, LAPIC_SW_ENABLE);
+
+    BSP_KINFO("Enabled Local APIC for BSP\n");
+    lapic_writel(LAPIC_LDR, LAPIC_STARTUP_LID);
+}
diff --git a/sys/arch/amd64/machdep.c b/sys/arch/amd64/machdep.c
index 0b52792..e6088a0 100644
--- a/sys/arch/amd64/machdep.c
+++ b/sys/arch/amd64/machdep.c
@@ -33,6 +33,7 @@
 #include <machine/idt.h>
 #include <machine/gdt.h>
 #include <machine/ioapic.h>
+#include <machine/lapic.h>
 
 #define ISR(func) ((uintptr_t)func)
 #define INIT_FLAG_IOAPIC 0x00000001U
@@ -71,6 +72,7 @@ processor_init(void)
         ioapic_init();
     }
 
+    lapic_init();       /* Per core */
     gdt_load(&g_gdtr);
     interrupts_init();
 }