LXR linux/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
  21static unsigned int nvram_size;
  22
  23static ssize_t opal_nvram_size(void)
  24{
  25        return nvram_size;
  26}
  27
  28static 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
  45static 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
  65void __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
  89