drivers/acpi/nvs.c

   1 /*
   2  * nvs.c - Routines for saving and restoring ACPI NVS memory region
   3  *
   4  * Copyright (C) 2008-2011 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
   5  *
   6  * This file is released under the GPLv2.
   7  */
   8
   9 #include <linux/io.h>
  10 #include <linux/kernel.h>
  11 #include <linux/list.h>
  12 #include <linux/mm.h>
  13 #include <linux/slab.h>
  14 #include <linux/acpi.h>
  15
  16 /*
  17  * Platforms, like ACPI, may want us to save some memory used by them during
  18  * suspend and to restore the contents of this memory during the subsequent
  19  * resume.  The code below implements a mechanism allowing us to do that.
  20  */
  21
  22 struct nvs_page {
  23         unsigned long phys_start;
  24         unsigned int size;
  25         void *kaddr;
  26         void *data;
  27         struct list_head node;
  28 };
  29
  30 static LIST_HEAD(nvs_list);
  31
  32 /**
  33  *      suspend_nvs_register - register platform NVS memory region to save
  34  *      @start - physical address of the region
  35  *      @size - size of the region
  36  *
  37  *      The NVS region need not be page-aligned (both ends) and we arrange
  38  *      things so that the data from page-aligned addresses in this region will
  39  *      be copied into separate RAM pages.
  40  */
  41 int suspend_nvs_register(unsigned long start, unsigned long size)
  42 {
  43         struct nvs_page *entry, *next;
  44
  45         while (size > 0) {
  46                 unsigned int nr_bytes;
  47
  48                 entry = kzalloc(sizeof(struct nvs_page), GFP_KERNEL);
  49                 if (!entry)
  50                         goto Error;
  51
  52                 list_add_tail(&entry->node, &nvs_list);
  53                 entry->phys_start = start;
  54                 nr_bytes = PAGE_SIZE - (start & ~PAGE_MASK);
  55                 entry->size = (size < nr_bytes) ? size : nr_bytes;
  56
  57                 start += entry->size;
  58                 size -= entry->size;
  59         }
  60         return 0;
  61
  62  Error:
  63         list_for_each_entry_safe(entry, next, &nvs_list, node) {
  64                 list_del(&entry->node);
  65                 kfree(entry);
  66         }
  67         return -ENOMEM;
  68 }
  69
  70 /**
  71  *      suspend_nvs_free - free data pages allocated for saving NVS regions
  72  */
  73 void suspend_nvs_free(void)
  74 {
  75         struct nvs_page *entry;
  76
  77         list_for_each_entry(entry, &nvs_list, node)
  78                 if (entry->data) {
  79                         free_page((unsigned long)entry->data);
  80                         entry->data = NULL;
  81                         if (entry->kaddr) {
  82                                 iounmap(entry->kaddr);
  83                                 entry->kaddr = NULL;
  84                         }
  85                 }
  86 }
  87
  88 /**
  89  *      suspend_nvs_alloc - allocate memory necessary for saving NVS regions
  90  */
  91 int suspend_nvs_alloc(void)
  92 {
  93         struct nvs_page *entry;
  94
  95         list_for_each_entry(entry, &nvs_list, node) {
  96                 entry->data = (void *)__get_free_page(GFP_KERNEL);
  97                 if (!entry->data) {
  98                         suspend_nvs_free();
  99                         return -ENOMEM;
 100                 }
 101         }
 102         return 0;
 103 }
 104
 105 /**
 106  *      suspend_nvs_save - save NVS memory regions
 107  */
 108 int suspend_nvs_save(void)
 109 {
 110         struct nvs_page *entry;
 111
 112         printk(KERN_INFO "PM: Saving platform NVS memory\n");
 113
 114         list_for_each_entry(entry, &nvs_list, node)
 115                 if (entry->data) {
 116                         entry->kaddr = ioremap(entry->phys_start, entry->size);
 117                         if (!entry->kaddr) {
 118                                 suspend_nvs_free();
 119                                 return -ENOMEM;
 120                         }
 121                         memcpy(entry->data, entry->kaddr, entry->size);
 122                 }
 123
 124         return 0;
 125 }
 126
 127 /**
 128  *      suspend_nvs_restore - restore NVS memory regions
 129  *
 130  *      This function is going to be called with interrupts disabled, so it
 131  *      cannot iounmap the virtual addresses used to access the NVS region.
 132  */
 133 void suspend_nvs_restore(void)
 134 {
 135         struct nvs_page *entry;
 136
 137         printk(KERN_INFO "PM: Restoring platform NVS memory\n");
 138
 139         list_for_each_entry(entry, &nvs_list, node)
 140                 if (entry->data)
 141                         memcpy(entry->kaddr, entry->data, entry->size);
 142 }