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/delay.h>
  15 #include <linux/kernel.h>
  16 #include <linux/init.h>
  17 #include <linux/of.h>
  18
  19 #include <asm/opal.h>
  20 #include <asm/nvram.h>
  21 #include <asm/machdep.h>
  22
  23 static unsigned int nvram_size;
  24
  25 static ssize_t opal_nvram_size(void)
  26 {
  27         return nvram_size;
  28 }
  29
  30 static ssize_t opal_nvram_read(char *buf, size_t count, loff_t *index)
  31 {
  32         s64 rc;
  33         int off;
  34
  35         if (*index >= nvram_size)
  36                 return 0;
  37         off = *index;
  38         if ((off + count) > nvram_size)
  39                 count = nvram_size - off;
  40         rc = opal_read_nvram(__pa(buf), count, off);
  41         if (rc != OPAL_SUCCESS)
  42                 return -EIO;
  43         *index += count;
  44         return count;
  45 }
  46
  47 /*
  48  * This can be called in the panic path with interrupts off, so use
  49  * mdelay in that case.
  50  */
  51 static ssize_t opal_nvram_write(char *buf, size_t count, loff_t *index)
  52 {
  53         s64 rc = OPAL_BUSY;
  54         int off;
  55
  56         if (*index >= nvram_size)
  57                 return 0;
  58         off = *index;
  59         if ((off + count) > nvram_size)
  60                 count = nvram_size - off;
  61
  62         while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
  63                 rc = opal_write_nvram(__pa(buf), count, off);
  64                 if (rc == OPAL_BUSY_EVENT) {
  65                         if (in_interrupt() || irqs_disabled())
  66                                 mdelay(OPAL_BUSY_DELAY_MS);
  67                         else
  68                                 msleep(OPAL_BUSY_DELAY_MS);
  69                         opal_poll_events(NULL);
  70                 } else if (rc == OPAL_BUSY) {
  71                         if (in_interrupt() || irqs_disabled())
  72                                 mdelay(OPAL_BUSY_DELAY_MS);
  73                         else
  74                                 msleep(OPAL_BUSY_DELAY_MS);
  75                 }
  76         }
  77
  78         if (rc)
  79                 return -EIO;
  80
  81         *index += count;
  82         return count;
  83 }
  84
  85 static int __init opal_nvram_init_log_partitions(void)
  86 {
  87         /* Scan nvram for partitions */
  88         nvram_scan_partitions();
  89         nvram_init_oops_partition(0);
  90         return 0;
  91 }
  92 machine_arch_initcall(powernv, opal_nvram_init_log_partitions);
  93
  94 void __init opal_nvram_init(void)
  95 {
  96         struct device_node *np;
  97         const __be32 *nbytes_p;
  98
  99         np = of_find_compatible_node(NULL, NULL, "ibm,opal-nvram");
 100         if (np == NULL)
 101                 return;
 102
 103         nbytes_p = of_get_property(np, "#bytes", NULL);
 104         if (!nbytes_p) {
 105                 of_node_put(np);
 106                 return;
 107         }
 108         nvram_size = be32_to_cpup(nbytes_p);
 109
 110         pr_info("OPAL nvram setup, %u bytes\n", nvram_size);
 111         of_node_put(np);
 112
 113         ppc_md.nvram_read = opal_nvram_read;
 114         ppc_md.nvram_write = opal_nvram_write;
 115         ppc_md.nvram_size = opal_nvram_size;
 116 }
 117