arch/ppc/syslib/prep_nvram.c

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