arch/ppc/syslib/prep_nvram.c

   1 /*
   2  * arch/ppc/kernel/prep_nvram.c
   3  *
   4  * Copyright (C) 1998  Corey Minyard
   5  *
   6  * This reads the NvRAM on PReP compliant machines (generally from IBM or
   7  * Motorola).  Motorola kept the format of NvRAM in their ROM, PPCBUG, the
   8  * same, long after they had stopped producing PReP compliant machines.  So
   9  * this code is useful in those cases as well.
  10  *
  11  */
  12 #include <linux/init.h>
  13 #include <linux/delay.h>
  14 #include <linux/slab.h>
  15 #include <linux/ioport.h>
  16
  17 #include <asm/sections.h>
  18 #include <asm/io.h>
  19 #include <asm/machdep.h>
  20 #include <asm/prep_nvram.h>
  21
  22 static char nvramData[MAX_PREP_NVRAM];
  23 static NVRAM_MAP *nvram=(NVRAM_MAP *)&nvramData[0];
  24
  25 unsigned char __prep prep_nvram_read_val(int addr)
  26 {
  27         outb(addr, PREP_NVRAM_AS0);
  28         outb(addr>>8, PREP_NVRAM_AS1);
  29         return inb(PREP_NVRAM_DATA);
  30 }
  31
  32 void __prep prep_nvram_write_val(int           addr,
  33                           unsigned char val)
  34 {
  35         outb(addr, PREP_NVRAM_AS0);
  36         outb(addr>>8, PREP_NVRAM_AS1);
  37         outb(val, PREP_NVRAM_DATA);
  38 }
  39
  40 void __init init_prep_nvram(void)
  41 {
  42         unsigned char *nvp;
  43         int  i;
  44         int  nvramSize;
  45
  46         /*
  47          * The following could fail if the NvRAM were corrupt but
  48          * we expect the boot firmware to have checked its checksum
  49          * before boot
  50          */
  51         nvp = (char *) &nvram->Header;
  52         for (i=0; i<sizeof(HEADER); i++)
  53         {
  54                 *nvp = ppc_md.nvram_read_val(i);
  55                 nvp++;
  56         }
  57
  58         /*
  59          * The PReP NvRAM may be any size so read in the header to
  60          * determine how much we must read in order to get the complete
  61          * GE area
  62          */
  63         nvramSize=(int)nvram->Header.GEAddress+nvram->Header.GELength;
  64         if(nvramSize>MAX_PREP_NVRAM)
  65         {
  66                 /*
  67                  * NvRAM is too large
  68                  */
  69                 nvram->Header.GELength=0;
  70                 return;
  71         }
  72
  73         /*
  74          * Read the remainder of the PReP NvRAM
  75          */
  76         nvp = (char *) &nvram->GEArea[0];
  77         for (i=sizeof(HEADER); i<nvramSize; i++)
  78         {
  79                 *nvp = ppc_md.nvram_read_val(i);
  80                 nvp++;
  81         }
  82 }
  83
  84 __prep
  85 char __prep *prep_nvram_get_var(const char *name)
  86 {
  87         char *cp;
  88         int  namelen;
  89
  90         namelen = strlen(name);
  91         cp = prep_nvram_first_var();
  92         while (cp != NULL) {
  93                 if ((strncmp(name, cp, namelen) == 0)
  94                     && (cp[namelen] == '='))
  95                 {
  96                         return cp+namelen+1;
  97                 }
  98                 cp = prep_nvram_next_var(cp);
  99         }
 100
 101         return NULL;
 102 }
 103
 104 __prep
 105 char __prep *prep_nvram_first_var(void)
 106 {
 107         if (nvram->Header.GELength == 0) {
 108                 return NULL;
 109         } else {
 110                 return (((char *)nvram)
 111                         + ((unsigned int) nvram->Header.GEAddress));
 112         }
 113 }
 114
 115 __prep
 116 char __prep *prep_nvram_next_var(char *name)
 117 {
 118         char *cp;
 119
 120
 121         cp = name;
 122         while (((cp - ((char *) nvram->GEArea)) < nvram->Header.GELength)
 123                && (*cp != '\0'))
 124         {
 125                 cp++;
 126         }
 127
 128         /* Skip over any null characters. */
 129         while (((cp - ((char *) nvram->GEArea)) < nvram->Header.GELength)
 130                && (*cp == '\0'))
 131         {
 132                 cp++;
 133         }
 134
 135         if ((cp - ((char *) nvram->GEArea)) < nvram->Header.GELength) {
 136                 return cp;
 137         } else {
 138                 return NULL;
 139         }
 140 }