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

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * PowerNV nvram code.
   4  *
   5  * Copyright 2011 IBM Corp.
   6  */
   7
   8 #define DEBUG
   9
  10 #include <linux/delay.h>
  11 #include <linux/kernel.h>
  12 #include <linux/init.h>
  13 #include <linux/of.h>
  14
  15 #include <asm/opal.h>
  16 #include <asm/nvram.h>
  17 #include <asm/machdep.h>
  18
  19 static unsigned int nvram_size;
  20
  21 static ssize_t opal_nvram_size(void)
  22 {
  23         return nvram_size;
  24 }
  25
  26 static ssize_t opal_nvram_read(char *buf, size_t count, loff_t *index)
  27 {
  28         s64 rc;
  29         int off;
  30
  31         if (*index >= nvram_size)
  32                 return 0;
  33         off = *index;
  34         if ((off + count) > nvram_size)
  35                 count = nvram_size - off;
  36         rc = opal_read_nvram(__pa(buf), count, off);
  37         if (rc != OPAL_SUCCESS)
  38                 return -EIO;
  39         *index += count;
  40         return count;
  41 }
  42
  43 /*
  44  * This can be called in the panic path with interrupts off, so use
  45  * mdelay in that case.
  46  */
  47 static ssize_t opal_nvram_write(char *buf, size_t count, loff_t *index)
  48 {
  49         s64 rc = OPAL_BUSY;
  50         int off;
  51
  52         if (*index >= nvram_size)
  53                 return 0;
  54         off = *index;
  55         if ((off + count) > nvram_size)
  56                 count = nvram_size - off;
  57
  58         while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
  59                 rc = opal_write_nvram(__pa(buf), count, off);
  60                 if (rc == OPAL_BUSY_EVENT) {
  61                         if (in_interrupt() || irqs_disabled())
  62                                 mdelay(OPAL_BUSY_DELAY_MS);
  63                         else
  64                                 msleep(OPAL_BUSY_DELAY_MS);
  65                         opal_poll_events(NULL);
  66                 } else if (rc == OPAL_BUSY) {
  67                         if (in_interrupt() || irqs_disabled())
  68                                 mdelay(OPAL_BUSY_DELAY_MS);
  69                         else
  70                                 msleep(OPAL_BUSY_DELAY_MS);
  71                 }
  72         }
  73
  74         if (rc)
  75                 return -EIO;
  76
  77         *index += count;
  78         return count;
  79 }
  80
  81 static int __init opal_nvram_init_log_partitions(void)
  82 {
  83         /* Scan nvram for partitions */
  84         nvram_scan_partitions();
  85         nvram_init_oops_partition(0);
  86         return 0;
  87 }
  88 machine_arch_initcall(powernv, opal_nvram_init_log_partitions);
  89
  90 void __init opal_nvram_init(void)
  91 {
  92         struct device_node *np;
  93         const __be32 *nbytes_p;
  94
  95         np = of_find_compatible_node(NULL, NULL, "ibm,opal-nvram");
  96         if (np == NULL)
  97                 return;
  98
  99         nbytes_p = of_get_property(np, "#bytes", NULL);
 100         if (!nbytes_p) {
 101                 of_node_put(np);
 102                 return;
 103         }
 104         nvram_size = be32_to_cpup(nbytes_p);
 105
 106         pr_info("OPAL nvram setup, %u bytes\n", nvram_size);
 107         of_node_put(np);
 108
 109         ppc_md.nvram_read = opal_nvram_read;
 110         ppc_md.nvram_write = opal_nvram_write;
 111         ppc_md.nvram_size = opal_nvram_size;
 112 }
 113