target/linux/adm5120/files-2.6.26/arch/mips/adm5120/prom/cfe.c

   1 /*
   2  *  Broadcom's CFE specific prom routines
   3  *
   4  *  Copyright (C) 2007-2008 Gabor Juhos <juhosg@openwrt.org>
   5  *
   6  *  This program is free software; you can redistribute it and/or modify it
   7  *  under the terms of the GNU General Public License version 2 as published
   8  *  by the Free Software Foundation.
   9  *
  10  */
  11
  12 #include <linux/types.h>
  13 #include <linux/init.h>
  14
  15 #include <asm/bootinfo.h>
  16 #include <asm/addrspace.h>
  17
  18 #include <prom/cfe.h>
  19 #include "prom_read.h"
  20
  21 /*
  22  * CFE based boards
  23  */
  24 #define CFE_EPTSEAL     0x43464531 /* CFE1 is the magic number to recognize CFE
  25 from other bootloaders */
  26
  27 static int cfe_found;
  28
  29 static u32 cfe_handle;
  30 static u32 cfe_entry;
  31 static u32 cfe_seal;
  32
  33 int __init cfe_present(void)
  34 {
  35         /*
  36          * This method only works, when we are booted directly from the CFE.
  37          */
  38         u32 a1 = (u32) fw_arg1;
  39
  40         if (cfe_found)
  41                 return 1;
  42
  43         cfe_handle = (u32) fw_arg0;
  44         cfe_entry = (u32) fw_arg2;
  45         cfe_seal = (u32) fw_arg3;
  46
  47         /* Check for CFE by finding the CFE magic number */
  48         if (cfe_seal != CFE_EPTSEAL)
  49                 return 0;
  50
  51         /* cfe_a1_val must be 0, because only one CPU present in the ADM5120 */
  52         if (a1 != 0)
  53                 return 0;
  54
  55         /* The cfe_handle, and the cfe_entry must be kernel mode addresses */
  56         if ((cfe_handle < KSEG0) || (cfe_entry < KSEG0))
  57                 return 0;
  58
  59         cfe_found = 1;
  60         return 1;
  61 }
  62
  63 char *cfe_getenv(char *envname)
  64 {
  65         if (cfe_found == 0)
  66                 return NULL;
  67
  68         return NULL;
  69 }