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/segment.h>
  19 #include <asm/io.h>
  20 #include <asm/machdep.h>
  21 #include <asm/prep_nvram.h>
  22
  23 static char nvramData[MAX_PREP_NVRAM];
  24 static NVRAM_MAP *nvram=(NVRAM_MAP *)&nvramData[0];
  25
  26 unsigned char __prep prep_nvram_read_val(int addr)
  27 {
  28         outb(addr, PREP_NVRAM_AS0);
  29         outb(addr>>8, PREP_NVRAM_AS1);
  30         return inb(PREP_NVRAM_DATA);
  31 }
  32
  33 void __prep prep_nvram_write_val(int           addr,
  34                           unsigned char val)
  35 {
  36         outb(addr, PREP_NVRAM_AS0);
  37         outb(addr>>8, PREP_NVRAM_AS1);
  38         outb(val, PREP_NVRAM_DATA);
  39 }
  40
  41 void __init init_prep_nvram(void)
  42 {
  43         unsigned char *nvp;
  44         int  i;
  45         int  nvramSize;
  46
  47         /*
  48          * The following could fail if the NvRAM were corrupt but
  49          * we expect the boot firmware to have checked its checksum
  50          * before boot
  51          */
  52         nvp = (char *) &nvram->Header;
  53         for (i=0; i<sizeof(HEADER); i++)
  54         {
  55                 *nvp = ppc_md.nvram_read_val(i);
  56                 nvp++;
  57         }
  58
  59         /*
  60          * The PReP NvRAM may be any size so read in the header to
  61          * determine how much we must read in order to get the complete
  62          * GE area
  63          */
  64         nvramSize=(int)nvram->Header.GEAddress+nvram->Header.GELength;
  65         if(nvramSize>MAX_PREP_NVRAM)
  66         {
  67                 /*
  68                  * NvRAM is too large
  69                  */
  70                 nvram->Header.GELength=0;
  71                 return;
  72         }
  73
  74         /*
  75          * Read the remainder of the PReP NvRAM
  76          */
  77         nvp = (char *) &nvram->GEArea[0];
  78         for (i=sizeof(HEADER); i<nvramSize; i++)
  79         {
  80                 *nvp = ppc_md.nvram_read_val(i);
  81                 nvp++;
  82         }
  83 }
  84
  85 __prep
  86 char __prep *prep_nvram_get_var(const char *name)
  87 {
  88         char *cp;
  89         int  namelen;
  90
  91         namelen = strlen(name);
  92         cp = prep_nvram_first_var();
  93         while (cp != NULL) {
  94                 if ((strncmp(name, cp, namelen) == 0)
  95                     && (cp[namelen] == '='))
  96                 {
  97                         return cp+namelen+1;
  98                 }
  99                 cp = prep_nvram_next_var(cp);
 100         }
 101
 102         return NULL;
 103 }
 104
 105 __prep
 106 char __prep *prep_nvram_first_var(void)
 107 {
 108         if (nvram->Header.GELength == 0) {
 109                 return NULL;
 110         } else {
 111                 return (((char *)nvram)
 112                         + ((unsigned int) nvram->Header.GEAddress));
 113         }
 114 }
 115
 116 __prep
 117 char __prep *prep_nvram_next_var(char *name)
 118 {
 119         char *cp;
 120
 121
 122         cp = name;
 123         while (((cp - ((char *) nvram->GEArea)) < nvram->Header.GELength)
 124                && (*cp != '\0'))
 125         {
 126                 cp++;
 127         }
 128
 129         /* Skip over any null characters. */
 130         while (((cp - ((char *) nvram->GEArea)) < nvram->Header.GELength)
 131                && (*cp == '\0'))
 132         {
 133                 cp++;
 134         }
 135
 136         if ((cp - ((char *) nvram->GEArea)) < nvram->Header.GELength) {
 137                 return cp;
 138         } else {
 139                 return NULL;
 140         }
 141 }