kernel/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/nvram.h>
  20 #include <asm/machdep.h>
  21
  22 static unsigned int nvram_size;
  23
  24 static ssize_t opal_nvram_size(void)
  25 {
  26         return nvram_size;
  27 }
  28
  29 static ssize_t opal_nvram_read(char *buf, size_t count, loff_t *index)
  30 {
  31         s64 rc;
  32         int off;
  33
  34         if (*index >= nvram_size)
  35                 return 0;
  36         off = *index;
  37         if ((off + count) > nvram_size)
  38                 count = nvram_size - off;
  39         rc = opal_read_nvram(__pa(buf), count, off);
  40         if (rc != OPAL_SUCCESS)
  41                 return -EIO;
  42         *index += count;
  43         return count;
  44 }
  45
  46 static ssize_t opal_nvram_write(char *buf, size_t count, loff_t *index)
  47 {
  48         s64 rc = OPAL_BUSY;
  49         int off;
  50
  51         if (*index >= nvram_size)
  52                 return 0;
  53         off = *index;
  54         if ((off + count) > nvram_size)
  55                 count = nvram_size - off;
  56
  57         while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
  58                 rc = opal_write_nvram(__pa(buf), count, off);
  59                 if (rc == OPAL_BUSY_EVENT)
  60                         opal_poll_events(NULL);
  61         }
  62         *index += count;
  63         return count;
  64 }
  65
  66 static int __init opal_nvram_init_log_partitions(void)
  67 {
  68         /* Scan nvram for partitions */
  69         nvram_scan_partitions();
  70         nvram_init_oops_partition(0);
  71         return 0;
  72 }
  73 machine_arch_initcall(powernv, opal_nvram_init_log_partitions);
  74
  75 void __init opal_nvram_init(void)
  76 {
  77         struct device_node *np;
  78         const __be32 *nbytes_p;
  79
  80         np = of_find_compatible_node(NULL, NULL, "ibm,opal-nvram");
  81         if (np == NULL)
  82                 return;
  83
  84         nbytes_p = of_get_property(np, "#bytes", NULL);
  85         if (!nbytes_p) {
  86                 of_node_put(np);
  87                 return;
  88         }
  89         nvram_size = be32_to_cpup(nbytes_p);
  90
  91         pr_info("OPAL nvram setup, %u bytes\n", nvram_size);
  92         of_node_put(np);
  93
  94         ppc_md.nvram_read = opal_nvram_read;
  95         ppc_md.nvram_write = opal_nvram_write;
  96         ppc_md.nvram_size = opal_nvram_size;
  97 }
  98