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 #include "internal.h"
  17
  18 /* ACPI NVS regions, APEI may use it */
  19
  20 struct nvs_region {
  21         __u64 phys_start;
  22         __u64 size;
  23         struct list_head node;
  24 };
  25
  26 static LIST_HEAD(nvs_region_list);
  27
  28 #ifdef CONFIG_ACPI_SLEEP
  29 static int suspend_nvs_register(unsigned long start, unsigned long size);
  30 #else
  31 static inline int suspend_nvs_register(unsigned long a, unsigned long b)
  32 {
  33         return 0;
  34 }
  35 #endif
  36
  37 int acpi_nvs_register(__u64 start, __u64 size)
  38 {
  39         struct nvs_region *region;
  40
  41         region = kmalloc(sizeof(*region), GFP_KERNEL);
  42         if (!region)
  43                 return -ENOMEM;
  44         region->phys_start = start;
  45         region->size = size;
  46         list_add_tail(&region->node, &nvs_region_list);
  47
  48         return suspend_nvs_register(start, size);
  49 }
  50
  51 int acpi_nvs_for_each_region(int (*func)(__u64 start, __u64 size, void *data),
  52                              void *data)
  53 {
  54         int rc;
  55         struct nvs_region *region;
  56
  57         list_for_each_entry(region, &nvs_region_list, node) {
  58                 rc = func(region->phys_start, region->size, data);
  59                 if (rc)
  60                         return rc;
  61         }
  62
  63         return 0;
  64 }
  65
  66
  67 #ifdef CONFIG_ACPI_SLEEP
  68 /*
  69  * Platforms, like ACPI, may want us to save some memory used by them during
  70  * suspend and to restore the contents of this memory during the subsequent
  71  * resume.  The code below implements a mechanism allowing us to do that.
  72  */
  73
  74 struct nvs_page {
  75         unsigned long phys_start;
  76         unsigned int size;
  77         void *kaddr;
  78         void *data;
  79         bool unmap;
  80         struct list_head node;
  81 };
  82
  83 static LIST_HEAD(nvs_list);
  84
  85 /**
  86  *      suspend_nvs_register - register platform NVS memory region to save
  87  *      @start - physical address of the region
  88  *      @size - size of the region
  89  *
  90  *      The NVS region need not be page-aligned (both ends) and we arrange
  91  *      things so that the data from page-aligned addresses in this region will
  92  *      be copied into separate RAM pages.
  93  */
  94 static int suspend_nvs_register(unsigned long start, unsigned long size)
  95 {
  96         struct nvs_page *entry, *next;
  97
  98         pr_info("PM: Registering ACPI NVS region [mem %#010lx-%#010lx] (%ld bytes)\n",
  99                 start, start + size - 1, size);
 100
 101         while (size > 0) {
 102                 unsigned int nr_bytes;
 103
 104                 entry = kzalloc(sizeof(struct nvs_page), GFP_KERNEL);
 105                 if (!entry)
 106                         goto Error;
 107
 108                 list_add_tail(&entry->node, &nvs_list);
 109                 entry->phys_start = start;
 110                 nr_bytes = PAGE_SIZE - (start & ~PAGE_MASK);
 111                 entry->size = (size < nr_bytes) ? size : nr_bytes;
 112
 113                 start += entry->size;
 114                 size -= entry->size;
 115         }
 116         return 0;
 117
 118  Error:
 119         list_for_each_entry_safe(entry, next, &nvs_list, node) {
 120                 list_del(&entry->node);
 121                 kfree(entry);
 122         }
 123         return -ENOMEM;
 124 }
 125
 126 /**
 127  *      suspend_nvs_free - free data pages allocated for saving NVS regions
 128  */
 129 void suspend_nvs_free(void)
 130 {
 131         struct nvs_page *entry;
 132
 133         list_for_each_entry(entry, &nvs_list, node)
 134                 if (entry->data) {
 135                         free_page((unsigned long)entry->data);
 136                         entry->data = NULL;
 137                         if (entry->kaddr) {
 138                                 if (entry->unmap) {
 139                                         iounmap(entry->kaddr);
 140                                         entry->unmap = false;
 141                                 } else {
 142                                         acpi_os_unmap_iomem(entry->kaddr,
 143                                                             entry->size);
 144                                 }
 145                                 entry->kaddr = NULL;
 146                         }
 147                 }
 148 }
 149
 150 /**
 151  *      suspend_nvs_alloc - allocate memory necessary for saving NVS regions
 152  */
 153 int suspend_nvs_alloc(void)
 154 {
 155         struct nvs_page *entry;
 156
 157         list_for_each_entry(entry, &nvs_list, node) {
 158                 entry->data = (void *)__get_free_page(GFP_KERNEL);
 159                 if (!entry->data) {
 160                         suspend_nvs_free();
 161                         return -ENOMEM;
 162                 }
 163         }
 164         return 0;
 165 }
 166
 167 /**
 168  *      suspend_nvs_save - save NVS memory regions
 169  */
 170 int suspend_nvs_save(void)
 171 {
 172         struct nvs_page *entry;
 173
 174         printk(KERN_INFO "PM: Saving platform NVS memory\n");
 175
 176         list_for_each_entry(entry, &nvs_list, node)
 177                 if (entry->data) {
 178                         unsigned long phys = entry->phys_start;
 179                         unsigned int size = entry->size;
 180
 181                         entry->kaddr = acpi_os_get_iomem(phys, size);
 182                         if (!entry->kaddr) {
 183                                 entry->kaddr = acpi_os_ioremap(phys, size);
 184                                 entry->unmap = !!entry->kaddr;
 185                         }
 186                         if (!entry->kaddr) {
 187                                 suspend_nvs_free();
 188                                 return -ENOMEM;
 189                         }
 190                         memcpy(entry->data, entry->kaddr, entry->size);
 191                 }
 192
 193         return 0;
 194 }
 195
 196 /**
 197  *      suspend_nvs_restore - restore NVS memory regions
 198  *
 199  *      This function is going to be called with interrupts disabled, so it
 200  *      cannot iounmap the virtual addresses used to access the NVS region.
 201  */
 202 void suspend_nvs_restore(void)
 203 {
 204         struct nvs_page *entry;
 205
 206         printk(KERN_INFO "PM: Restoring platform NVS memory\n");
 207
 208         list_for_each_entry(entry, &nvs_list, node)
 209                 if (entry->data)
 210                         memcpy(entry->kaddr, entry->data, entry->size);
 211 }
 212 #endif