arch/powerpc/platforms/pseries/nvram.c

   1 /*
   2  *  c 2001 PPC 64 Team, IBM Corp
   3  *
   4  *      This program is free software; you can redistribute it and/or
   5  *      modify it under the terms of the GNU General Public License
   6  *      as published by the Free Software Foundation; either version
   7  *      2 of the License, or (at your option) any later version.
   8  *
   9  * /dev/nvram driver for PPC64
  10  *
  11  * This perhaps should live in drivers/char
  12  */
  13
  14
  15 #include <linux/types.h>
  16 #include <linux/errno.h>
  17 #include <linux/init.h>
  18 #include <linux/slab.h>
  19 #include <linux/spinlock.h>
  20 #include <asm/uaccess.h>
  21 #include <asm/nvram.h>
  22 #include <asm/rtas.h>
  23 #include <asm/prom.h>
  24 #include <asm/machdep.h>
  25
  26 static unsigned int nvram_size;
  27 static int nvram_fetch, nvram_store;
  28 static char nvram_buf[NVRW_CNT];        /* assume this is in the first 4GB */
  29 static DEFINE_SPINLOCK(nvram_lock);
  30
  31
  32 static ssize_t pSeries_nvram_read(char *buf, size_t count, loff_t *index)
  33 {
  34         unsigned int i;
  35         unsigned long len;
  36         int done;
  37         unsigned long flags;
  38         char *p = buf;
  39
  40
  41         if (nvram_size == 0 || nvram_fetch == RTAS_UNKNOWN_SERVICE)
  42                 return -ENODEV;
  43
  44         if (*index >= nvram_size)
  45                 return 0;
  46
  47         i = *index;
  48         if (i + count > nvram_size)
  49                 count = nvram_size - i;
  50
  51         spin_lock_irqsave(&nvram_lock, flags);
  52
  53         for (; count != 0; count -= len) {
  54                 len = count;
  55                 if (len > NVRW_CNT)
  56                         len = NVRW_CNT;
  57
  58                 if ((rtas_call(nvram_fetch, 3, 2, &done, i, __pa(nvram_buf),
  59                                len) != 0) || len != done) {
  60                         spin_unlock_irqrestore(&nvram_lock, flags);
  61                         return -EIO;
  62                 }
  63
  64                 memcpy(p, nvram_buf, len);
  65
  66                 p += len;
  67                 i += len;
  68         }
  69
  70         spin_unlock_irqrestore(&nvram_lock, flags);
  71
  72         *index = i;
  73         return p - buf;
  74 }
  75
  76 static ssize_t pSeries_nvram_write(char *buf, size_t count, loff_t *index)
  77 {
  78         unsigned int i;
  79         unsigned long len;
  80         int done;
  81         unsigned long flags;
  82         const char *p = buf;
  83
  84         if (nvram_size == 0 || nvram_store == RTAS_UNKNOWN_SERVICE)
  85                 return -ENODEV;
  86
  87         if (*index >= nvram_size)
  88                 return 0;
  89
  90         i = *index;
  91         if (i + count > nvram_size)
  92                 count = nvram_size - i;
  93
  94         spin_lock_irqsave(&nvram_lock, flags);
  95
  96         for (; count != 0; count -= len) {
  97                 len = count;
  98                 if (len > NVRW_CNT)
  99                         len = NVRW_CNT;
 100
 101                 memcpy(nvram_buf, p, len);
 102
 103                 if ((rtas_call(nvram_store, 3, 2, &done, i, __pa(nvram_buf),
 104                                len) != 0) || len != done) {
 105                         spin_unlock_irqrestore(&nvram_lock, flags);
 106                         return -EIO;
 107                 }
 108
 109                 p += len;
 110                 i += len;
 111         }
 112         spin_unlock_irqrestore(&nvram_lock, flags);
 113
 114         *index = i;
 115         return p - buf;
 116 }
 117
 118 static ssize_t pSeries_nvram_get_size(void)
 119 {
 120         return nvram_size ? nvram_size : -ENODEV;
 121 }
 122
 123 int __init pSeries_nvram_init(void)
 124 {
 125         struct device_node *nvram;
 126         const unsigned int *nbytes_p;
 127         unsigned int proplen;
 128
 129         nvram = of_find_node_by_type(NULL, "nvram");
 130         if (nvram == NULL)
 131                 return -ENODEV;
 132
 133         nbytes_p = get_property(nvram, "#bytes", &proplen);
 134         if (nbytes_p == NULL || proplen != sizeof(unsigned int))
 135                 return -EIO;
 136
 137         nvram_size = *nbytes_p;
 138
 139         nvram_fetch = rtas_token("nvram-fetch");
 140         nvram_store = rtas_token("nvram-store");
 141         printk(KERN_INFO "PPC64 nvram contains %d bytes\n", nvram_size);
 142         of_node_put(nvram);
 143
 144         ppc_md.nvram_read       = pSeries_nvram_read;
 145         ppc_md.nvram_write      = pSeries_nvram_write;
 146         ppc_md.nvram_size       = pSeries_nvram_get_size;
 147
 148         return 0;
 149 }