arch/all-pc/acpi/findsdt.c

   1 #include <aros/debug.h>
   2 #include <resources/acpi.h>
   3
   4 /*****************************************************************************
   5
   6     NAME */
   7 #include <proto/acpi.h>
   8
   9         AROS_LH1(APTR, ACPI_FindSDT,
  10
  11 /*  SYNOPSIS */
  12         AROS_LHA(ULONG, id, D0),
  13
  14 /*  LOCATION */
  15         struct ACPIBase *, ACPIBase, 1, Acpi)
  16
  17 /*  FUNCTION
  18         Locate a system description table with a given 4-character ID
  19
  20     INPUTS
  21         id - a table ID (use ACPI_MAKE_ID() macro to get it)
  22
  23     RESULT
  24         A pointer to a table or NULL if can't be found
  25
  26     NOTES
  27         Some systems may include duplicating tables, often it's MADT.
  28         In this case a table with the latest revision number will
  29         be returned.
  30
  31     EXAMPLE
  32
  33     BUGS
  34
  35     SEE ALSO
  36
  37     INTERNALS
  38
  39 ******************************************************************************/
  40 {
  41     AROS_LIBFUNC_INIT
  42
  43     struct ACPI_TABLE_DEF_HEADER *found = NULL;
  44     struct ACPI_TABLE_DEF_HEADER *header;
  45     unsigned int i;
  46
  47     D(bug("[ACPI] acpi_LocateSDT('%4.4s')\n", &id));
  48
  49     /* Locate the table. */
  50     for (i = 0; i < ACPIBase->ACPIB_SDT_Count; i++)
  51     {
  52         header = ACPIBase->ACPIB_SDT_Entry[i];
  53
  54         if (header->signature == id)
  55         {
  56             D(bug("[ACPI] acpi_LocateSDT: Table %4.4s pointer 0x%p rev %u\n", &header->signature, header, header->revision));
  57
  58             /*
  59              * Some firmwares have a strange thing - they contain multiple tables with the same signature
  60              * and different revisions. A common example is MADT table.
  61              * Here we select a table with the latest revision. ACPI specs don't say anything clear
  62              * about this.
  63              * Such behavior is exposed for example by MacMini EFI.
  64              */
  65             if ((found == NULL) || (header->revision > found->revision))
  66                 found = header;
  67         }
  68     }
  69
  70     return found;
  71
  72     AROS_LIBFUNC_EXIT
  73 }