target/linux/adm5120-2.6/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
  10  *  modify it under the terms of the GNU General Public License
  11  *  as published by the Free Software Foundation; either version 2
  12  *  of the License, or (at your option) any later version.
  13  *
  14  *  This program is distributed in the hope that it will be useful,
  15  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  *  GNU General Public License for more details.
  18  *
  19  *  You should have received a copy of the GNU General Public License
  20  *  along with this program; if not, write to the
  21  *  Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  22  *  Boston, MA  02110-1301, USA.
  23  */
  24
  25 #include <linux/types.h>
  26 #include <linux/init.h>
  27
  28 #include <asm/bootinfo.h>
  29 #include <asm/addrspace.h>
  30
  31 #include <prom/cfe.h>
  32 #include "prom_read.h"
  33
  34 /*
  35  * CFE based boards
  36  */
  37 #define CFE_EPTSEAL     0x43464531 /* CFE1 is the magic number to recognize CFE
  38 from other bootloaders */
  39
  40 static int cfe_found = 0;
  41
  42 static u32 cfe_handle;
  43 static u32 cfe_entry;
  44 static u32 cfe_seal;
  45
  46 int __init cfe_present(void)
  47 {
  48         /*
  49          * This method only works, when we are booted directly from the CFE.
  50          */
  51         u32 a1 = (u32) fw_arg1;
  52
  53         if (cfe_found)
  54                 return 1;
  55
  56         cfe_handle = (u32) fw_arg0;
  57         cfe_entry = (u32) fw_arg2;
  58         cfe_seal = (u32) fw_arg3;
  59
  60         /* Check for CFE by finding the CFE magic number */
  61         if (cfe_seal != CFE_EPTSEAL) {
  62                 /* We are not booted from CFE */
  63                 return 0;
  64         }
  65
  66         /* cfe_a1_val must be 0, because only one CPU present in the ADM5120 */
  67         if (a1 != 0) {
  68                 return 0;
  69         }
  70
  71         /* The cfe_handle, and the cfe_entry must be kernel mode addresses */
  72         if ((cfe_handle < KSEG0) || (cfe_entry < KSEG0)) {
  73                 return 0;
  74         }
  75
  76         cfe_found = 1;
  77         return 1;
  78 }
  79
  80 char *cfe_getenv(char *envname)
  81 {
  82         if (cfe_found == 0)
  83                 return NULL;
  84
  85         return NULL;
  86 }