target/linux/adm5120/files/arch/mips/adm5120/prom/cfe.c

   1 /*
   2  *  $Id$
   3  *
   4  *  Broadcom's CFE specific prom routines
   5  *
   6  *  Copyright (C) 2007 OpenWrt.org
   7  *  Copyright (C) 2007 Gabor Juhos <juhosg at openwrt.org>
   8  *
   9  *  This program is free software; you can redistribute it and/or modify it
  10  *  under the terms of the GNU General Public License version 2 as published
  11  *  by the Free Software Foundation.
  12  *
  13  */
  14
  15 #include <linux/types.h>
  16 #include <linux/init.h>
  17
  18 #include <asm/bootinfo.h>
  19 #include <asm/addrspace.h>
  20
  21 #include <prom/cfe.h>
  22 #include "prom_read.h"
  23
  24 /*
  25  * CFE based boards
  26  */
  27 #define CFE_EPTSEAL     0x43464531 /* CFE1 is the magic number to recognize CFE
  28 from other bootloaders */
  29
  30 static int cfe_found;
  31
  32 static u32 cfe_handle;
  33 static u32 cfe_entry;
  34 static u32 cfe_seal;
  35
  36 int __init cfe_present(void)
  37 {
  38         /*
  39          * This method only works, when we are booted directly from the CFE.
  40          */
  41         u32 a1 = (u32) fw_arg1;
  42
  43         if (cfe_found)
  44                 return 1;
  45
  46         cfe_handle = (u32) fw_arg0;
  47         cfe_entry = (u32) fw_arg2;
  48         cfe_seal = (u32) fw_arg3;
  49
  50         /* Check for CFE by finding the CFE magic number */
  51         if (cfe_seal != CFE_EPTSEAL)
  52                 return 0;
  53
  54         /* cfe_a1_val must be 0, because only one CPU present in the ADM5120 */
  55         if (a1 != 0)
  56                 return 0;
  57
  58         /* The cfe_handle, and the cfe_entry must be kernel mode addresses */
  59         if ((cfe_handle < KSEG0) || (cfe_entry < KSEG0))
  60                 return 0;
  61
  62         cfe_found = 1;
  63         return 1;
  64 }
  65
  66 char *cfe_getenv(char *envname)
  67 {
  68         if (cfe_found == 0)
  69                 return NULL;
  70
  71         return NULL;
  72 }