arch/powerpc/platforms/powernv/opal-nvram.c

   1 /*
   2  * PowerNV nvram code.
   3  *
   4  * Copyright 2011 IBM Corp.
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #define DEBUG
  13
  14 #include <linux/kernel.h>
  15 #include <linux/init.h>
  16 #include <linux/of.h>
  17
  18 #include <asm/opal.h>
  19 #include <asm/machdep.h>
  20
  21 static unsigned int nvram_size;
  22
  23 static ssize_t opal_nvram_size(void)
  24 {
  25         return nvram_size;
  26 }
  27
  28 static ssize_t opal_nvram_read(char *buf, size_t count, loff_t *index)
  29 {
  30         s64 rc;
  31         int off;
  32
  33         if (*index >= nvram_size)
  34                 return 0;
  35         off = *index;
  36         if ((off + count) > nvram_size)
  37                 count = nvram_size - off;
  38         rc = opal_read_nvram(__pa(buf), count, off);
  39         if (rc != OPAL_SUCCESS)
  40                 return -EIO;
  41         *index += count;
  42         return count;
  43 }
  44
  45 static ssize_t opal_nvram_write(char *buf, size_t count, loff_t *index)
  46 {
  47         s64 rc = OPAL_BUSY;
  48         int off;
  49
  50         if (*index >= nvram_size)
  51                 return 0;
  52         off = *index;
  53         if ((off + count) > nvram_size)
  54                 count = nvram_size - off;
  55
  56         while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
  57                 rc = opal_write_nvram(__pa(buf), count, off);
  58                 if (rc == OPAL_BUSY_EVENT)
  59                         opal_poll_events(NULL);
  60         }
  61         *index += count;
  62         return count;
  63 }
  64
  65 void __init opal_nvram_init(void)
  66 {
  67         struct device_node *np;
  68         const u32 *nbytes_p;
  69
  70         np = of_find_compatible_node(NULL, NULL, "ibm,opal-nvram");
  71         if (np == NULL)
  72                 return;
  73
  74         nbytes_p = of_get_property(np, "#bytes", NULL);
  75         if (!nbytes_p) {
  76                 of_node_put(np);
  77                 return;
  78         }
  79         nvram_size = *nbytes_p;
  80
  81         printk(KERN_INFO "OPAL nvram setup, %u bytes\n", nvram_size);
  82         of_node_put(np);
  83
  84         ppc_md.nvram_read = opal_nvram_read;
  85         ppc_md.nvram_write = opal_nvram_write;
  86         ppc_md.nvram_size = opal_nvram_size;
  87 }
  88