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 <linux/acpi_io.h>
  16 #include <acpi/acpiosxf.h>
  17
  18 /*
  19  * Platforms, like ACPI, may want us to save some memory used by them during
  20  * suspend and to restore the contents of this memory during the subsequent
  21  * resume.  The code below implements a mechanism allowing us to do that.
  22  */
  23
  24 struct nvs_page {
  25         unsigned long phys_start;
  26         unsigned int size;
  27         void *kaddr;
  28         void *data;
  29         bool unmap;
  30         struct list_head node;
  31 };
  32
  33 static LIST_HEAD(nvs_list);
  34
  35 /**
  36  *      suspend_nvs_register - register platform NVS memory region to save
  37  *      @start - physical address of the region
  38  *      @size - size of the region
  39  *
  40  *      The NVS region need not be page-aligned (both ends) and we arrange
  41  *      things so that the data from page-aligned addresses in this region will
  42  *      be copied into separate RAM pages.
  43  */
  44 int suspend_nvs_register(unsigned long start, unsigned long size)
  45 {
  46         struct nvs_page *entry, *next;
  47
  48         pr_info("PM: Registering ACPI NVS region at %lx (%ld bytes)\n",
  49                 start, size);
  50
  51         while (size > 0) {
  52                 unsigned int nr_bytes;
  53
  54                 entry = kzalloc(sizeof(struct nvs_page), GFP_KERNEL);
  55                 if (!entry)
  56                         goto Error;
  57
  58                 list_add_tail(&entry->node, &nvs_list);
  59                 entry->phys_start = start;
  60                 nr_bytes = PAGE_SIZE - (start & ~PAGE_MASK);
  61                 entry->size = (size < nr_bytes) ? size : nr_bytes;
  62
  63                 start += entry->size;
  64                 size -= entry->size;
  65         }
  66         return 0;
  67
  68  Error:
  69         list_for_each_entry_safe(entry, next, &nvs_list, node) {
  70                 list_del(&entry->node);
  71                 kfree(entry);
  72         }
  73         return -ENOMEM;
  74 }
  75
  76 /**
  77  *      suspend_nvs_free - free data pages allocated for saving NVS regions
  78  */
  79 void suspend_nvs_free(void)
  80 {
  81         struct nvs_page *entry;
  82
  83         list_for_each_entry(entry, &nvs_list, node)
  84                 if (entry->data) {
  85                         free_page((unsigned long)entry->data);
  86                         entry->data = NULL;
  87                         if (entry->kaddr) {
  88                                 if (entry->unmap) {
  89                                         iounmap(entry->kaddr);
  90                                         entry->unmap = false;
  91                                 } else {
  92                                         acpi_os_unmap_memory(entry->kaddr,
  93                                                              entry->size);
  94                                 }
  95                                 entry->kaddr = NULL;
  96                         }
  97                 }
  98 }
  99
 100 /**
 101  *      suspend_nvs_alloc - allocate memory necessary for saving NVS regions
 102  */
 103 int suspend_nvs_alloc(void)
 104 {
 105         struct nvs_page *entry;
 106
 107         list_for_each_entry(entry, &nvs_list, node) {
 108                 entry->data = (void *)__get_free_page(GFP_KERNEL);
 109                 if (!entry->data) {
 110                         suspend_nvs_free();
 111                         return -ENOMEM;
 112                 }
 113         }
 114         return 0;
 115 }
 116
 117 /**
 118  *      suspend_nvs_save - save NVS memory regions
 119  */
 120 int suspend_nvs_save(void)
 121 {
 122         struct nvs_page *entry;
 123
 124         printk(KERN_INFO "PM: Saving platform NVS memory\n");
 125
 126         list_for_each_entry(entry, &nvs_list, node)
 127                 if (entry->data) {
 128                         unsigned long phys = entry->phys_start;
 129                         unsigned int size = entry->size;
 130
 131                         entry->kaddr = acpi_os_get_iomem(phys, size);
 132                         if (!entry->kaddr) {
 133                                 entry->kaddr = acpi_os_ioremap(phys, size);
 134                                 entry->unmap = !!entry->kaddr;
 135                         }
 136                         if (!entry->kaddr) {
 137                                 suspend_nvs_free();
 138                                 return -ENOMEM;
 139                         }
 140                         memcpy(entry->data, entry->kaddr, entry->size);
 141                 }
 142
 143         return 0;
 144 }
 145
 146 /**
 147  *      suspend_nvs_restore - restore NVS memory regions
 148  *
 149  *      This function is going to be called with interrupts disabled, so it
 150  *      cannot iounmap the virtual addresses used to access the NVS region.
 151  */
 152 void suspend_nvs_restore(void)
 153 {
 154         struct nvs_page *entry;
 155
 156         printk(KERN_INFO "PM: Restoring platform NVS memory\n");
 157
 158         list_for_each_entry(entry, &nvs_list, node)
 159                 if (entry->data)
 160                         memcpy(entry->kaddr, entry->data, entry->size);
 161 }