APIC, HPET, virtual memory

2025-12-22 19:36:43 +01:00
parent 741d0fb9b0
commit 7b33d0757a
13 changed files with 495 additions and 3 deletions
--- a/kernel/amd64/hpet.c
+++ b/kernel/amd64/hpet.c
@@ -0,0 +1,73 @@
+#include <amd64/hpet.h>
+#include <libk/std.h>
+#include <limine/requests.h>
+#include <sys/debug.h>
+#include <sys/mm.h>
+#include <uacpi/acpi.h>
+#include <uacpi/status.h>
+#include <uacpi/tables.h>
+#include <uacpi/uacpi.h>
+
+#define HPET_MCVR  0xF0 /* Main Counter Value Register            */
+#define HPET_GCR   0x10 /* General Configuration Register         */
+#define HPET_GCIDR 0x00 /* General Capabilities and ID Register   */
+
+static bool hpet_32bits = 1;
+static uintptr_t hpet_paddr;
+static uint64_t hpet_clock_nano;
+
+extern void amd64_spin (void);
+
+static uint64_t amd64_hpet_read (uint32_t reg) {
+  struct limine_hhdm_response* hhdm = limine_hhdm_request.response;
+  uintptr_t hpet_vaddr = hpet_paddr + (uintptr_t)hhdm->offset;
+  return (hpet_32bits ? *(volatile uint32_t*)(hpet_vaddr + reg)
+                      : *(volatile uint64_t*)(hpet_vaddr + reg));
+}
+
+static void amd64_hpet_write (uint32_t reg, uint64_t value) {
+  struct limine_hhdm_response* hhdm = limine_hhdm_request.response;
+  uintptr_t hpet_vaddr = hpet_paddr + (uintptr_t)hhdm->offset;
+  if (hpet_32bits)
+    *(volatile uint32_t*)(hpet_vaddr + reg) = (value & 0xFFFFFFFF);
+  else
+    *(volatile uint64_t*)(hpet_vaddr + reg) = value;
+}
+
+static uint64_t amd64_hpet_timestamp (void) {
+  return amd64_hpet_read (HPET_MCVR);
+}
+
+uint64_t amd64_hpet_current_nano (void) {
+  return amd64_hpet_timestamp () * hpet_clock_nano;
+}
+
+void amd64_hpet_sleep_micro (uint64_t us) {
+  uint64_t start = amd64_hpet_timestamp ();
+  uint64_t conv = us * 1000;
+  while (((amd64_hpet_timestamp () - start) * hpet_clock_nano) < conv)
+    __asm__ volatile ("pause" ::: "memory");
+}
+
+void amd64_hpet_init (void) {
+  struct uacpi_table hpet_table;
+  uacpi_status status =
+      uacpi_table_find_by_signature (ACPI_HPET_SIGNATURE, &hpet_table);
+  if (status != UACPI_STATUS_OK) {
+    DEBUG ("Could not find HPET table!\n");
+    amd64_spin ();
+  }
+
+  struct acpi_hpet* hpet = (struct acpi_hpet*)hpet_table.virt_addr;
+  hpet_paddr = (uintptr_t)hpet->address.address;
+
+  struct limine_hhdm_response* hhdm = limine_hhdm_request.response;
+  mm_map_kernel_page (hpet_paddr, (uintptr_t)hhdm->offset + hpet_paddr,
+                      MM_PG_PRESENT | MM_PG_RW);
+
+  hpet_32bits = (amd64_hpet_read (HPET_GCIDR) & (1 << 13)) ? 0 : 1;
+
+  amd64_hpet_write (HPET_GCR, amd64_hpet_read (HPET_GCR) | 0x01);
+
+  hpet_clock_nano = amd64_hpet_read (HPET_GCIDR + 4) / 1000000;
+}