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 #include <acpi/acpiosxf.h>
  16
  17 /*
  18  * Platforms, like ACPI, may want us to save some memory used by them during
  19  * suspend and to restore the contents of this memory during the subsequent
  20  * resume.  The code below implements a mechanism allowing us to do that.
  21  */
  22
  23 struct nvs_page {
  24         unsigned long phys_start;
  25         unsigned int size;
  26         void *kaddr;
  27         void *data;
  28         struct list_head node;
  29 };
  30
  31 static LIST_HEAD(nvs_list);
  32
  33 /**
  34  *      suspend_nvs_register - register platform NVS memory region to save
  35  *      @start - physical address of the region
  36  *      @size - size of the region
  37  *
  38  *      The NVS region need not be page-aligned (both ends) and we arrange
  39  *      things so that the data from page-aligned addresses in this region will
  40  *      be copied into separate RAM pages.
  41  */
  42 int suspend_nvs_register(unsigned long start, unsigned long size)
  43 {
  44         struct nvs_page *entry, *next;
  45
  46         while (size > 0) {
  47                 unsigned int nr_bytes;
  48
  49                 entry = kzalloc(sizeof(struct nvs_page), GFP_KERNEL);
  50                 if (!entry)
  51                         goto Error;
  52
  53                 list_add_tail(&entry->node, &nvs_list);
  54                 entry->phys_start = start;
  55                 nr_bytes = PAGE_SIZE - (start & ~PAGE_MASK);
  56                 entry->size = (size < nr_bytes) ? size : nr_bytes;
  57
  58                 start += entry->size;
  59                 size -= entry->size;
  60         }
  61         return 0;
  62
  63  Error:
  64         list_for_each_entry_safe(entry, next, &nvs_list, node) {
  65                 list_del(&entry->node);
  66                 kfree(entry);
  67         }
  68         return -ENOMEM;
  69 }
  70
  71 /**
  72  *      suspend_nvs_free - free data pages allocated for saving NVS regions
  73  */
  74 void suspend_nvs_free(void)
  75 {
  76         struct nvs_page *entry;
  77
  78         list_for_each_entry(entry, &nvs_list, node)
  79                 if (entry->data) {
  80                         free_page((unsigned long)entry->data);
  81                         entry->data = NULL;
  82                         if (entry->kaddr) {
  83                                 acpi_os_unmap_memory(entry->kaddr, entry->size);
  84                                 entry->kaddr = NULL;
  85                         }
  86                 }
  87 }
  88
  89 /**
  90  *      suspend_nvs_alloc - allocate memory necessary for saving NVS regions
  91  */
  92 int suspend_nvs_alloc(void)
  93 {
  94         struct nvs_page *entry;
  95
  96         list_for_each_entry(entry, &nvs_list, node) {
  97                 entry->data = (void *)__get_free_page(GFP_KERNEL);
  98                 if (!entry->data) {
  99                         suspend_nvs_free();
 100                         return -ENOMEM;
 101                 }
 102         }
 103         return 0;
 104 }
 105
 106 /**
 107  *      suspend_nvs_save - save NVS memory regions
 108  */
 109 int suspend_nvs_save(void)
 110 {
 111         struct nvs_page *entry;
 112
 113         printk(KERN_INFO "PM: Saving platform NVS memory\n");
 114
 115         list_for_each_entry(entry, &nvs_list, node)
 116                 if (entry->data) {
 117                         entry->kaddr = acpi_os_map_memory(entry->phys_start,
 118                                                           entry->size);
 119                         if (!entry->kaddr) {
 120                                 suspend_nvs_free();
 121                                 return -ENOMEM;
 122                         }
 123                         memcpy(entry->data, entry->kaddr, entry->size);
 124                 }
 125
 126         return 0;
 127 }
 128
 129 /**
 130  *      suspend_nvs_restore - restore NVS memory regions
 131  *
 132  *      This function is going to be called with interrupts disabled, so it
 133  *      cannot iounmap the virtual addresses used to access the NVS region.
 134  */
 135 void suspend_nvs_restore(void)
 136 {
 137         struct nvs_page *entry;
 138
 139         printk(KERN_INFO "PM: Restoring platform NVS memory\n");
 140
 141         list_for_each_entry(entry, &nvs_list, node)
 142                 if (entry->data)
 143                         memcpy(entry->kaddr, entry->data, entry->size);
 144 }