[MODERN FEATURES] ACPI tables

2016-11-20 00:22:13 +01:00
parent d801e0fd6c
commit 56d5fea388
6 changed files with 193 additions and 5 deletions
--- a/kernel/arch/acpi.c
+++ b/kernel/arch/acpi.c
@@ -0,0 +1,117 @@
+#include <acpi.h>
+#include <stdint.h>
+#include <debug.h>
+#include <mem.h>
+#include <string.h>
+#include <multiboot.h>
+
+RSDP_st *find_rsdp()
+{
+  // The Root System Description Pointer (RSDP) should be found either
+  // - in the first 1 KB of the EBDA
+  // - between 0xE0000 and 0xFFFFF
+  // We'll only try the second alternative for now
+
+  uintptr_t start = KERNEL_OFFSET + 0xE0000;
+  uintptr_t end = KERNEL_OFFSET + 0xFFFFF;
+
+  uint8_t *p = (void *)start;
+  while((uintptr_t)p < end)
+  {
+    // The RSDP is identified by a signature string
+    if(!(memcmp(p, "RSD PTR ", 8)))
+    {
+      // Make sure we got it right by calculating the checksum
+      uint8_t checksum = 0;
+      for(int i = 0; i < 20; i++)
+        checksum += p[i];
+      if(!checksum)
+        break;
+    }
+    // The RSDP must be 16-byte aligned
+    p = incptr(p, 16);
+  }
+  if((uintptr_t)p >= end)
+    return 0;
+  return (void *)p;
+}
+
+SDT_header *find_SDT(RSDP_st *rsdp, char *signature)
+{
+  // Scan through the RSDT or XSDT for a header with the wanted signature
+
+  // Read RSDT if revision <= 1.0
+  // else read XSDT
+  unsigned int bpp = (!rsdp->revision)?4:8;
+  SDT_header *rsdt = (bpp == 4) ? P2V(rsdp->RSDT_p) : P2V(rsdp->XSDT_p);
+
+  int entries = (rsdt->length - sizeof(SDT_header))/bpp;
+  for(int i = 0; i < entries; i++)
+  {
+    // 32 bit pointers if revision <= 1.0
+    // otherwise 64 bit pointers
+    SDT_header *h = (bpp == 4) ?
+      P2V(*(uint32_t*)&rsdt->data[i*bpp]) :
+      P2V(*(uint64_t*)&rsdt->data[i*bpp]);
+
+    // Return pointer if signature is correct
+    if(!memcmp(h->signature, signature, 4))
+      return h;
+  }
+  return 0;
+}
+
+void parse_MADT(SDT_header *header)
+{
+  MADT_header *madt = (MADT_header *)header->data;
+  // Save the memory mapping of the local APIC
+
+  // TODO: In bochs, there are MADT entries with 0 length. I assume parsing should stop here.
+  // TODO: Look this up
+  for(MADT_field *f = (void*)madt->fields;
+      (uintptr_t)f < (uintptr_t)madt + header->length && f->length;
+      f = incptr(f, f->length))
+  {
+    switch(f->type)
+    {
+      case 0: // Processor Local APIC entry
+        debug_info("ACPI - Processor id:%x LAPIC:%x", f->proc.proc_ID, f->proc.APIC_ID);
+        if(f->proc.flags & 0x1)
+        {
+          debug(" enabled");
+        }
+        debug("\n");
+        break;
+      case 1: // I/O APIC entry
+        debug_info("ACPI - IOAPIC id:%x address:%x\n", f->IOAPIC.APIC_ID, f->IOAPIC.address);
+        break;
+      case 2: // Interrupt Source Override
+        debug_info("ACPI - Interrupt source override %x->%x\n", f->ISO.irq, f->ISO.interrupt);
+        break;
+      default:
+        break;
+    }
+  }
+}
+
+void acpi_init()
+{
+  RSDP_st *rsdp;
+  if(!(rsdp = mboot_data.rsdp))
+  {
+    if(!(rsdp = find_rsdp()))
+    {
+    debug_error("PANIC: ACPI - No RSDP found!");
+    for(;;);
+    }
+  }
+
+  debug_info("ACPI - ACPI version %s\n", (rsdp->revision)?"2.0":"1.0");
+
+  // Scan for MADT
+  SDT_header *madt = find_SDT(rsdp, "APIC");
+  // Read processor info from MADT
+  parse_MADT(madt);
+  // Ignore all other tables for now
+
+}