2 * nvs.c - Routines for saving and restoring ACPI NVS memory region
4 * Copyright (C) 2008-2011 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
6 * This file is released under the GPLv2.
10 #include <linux/kernel.h>
11 #include <linux/list.h>
13 #include <linux/slab.h>
14 #include <linux/acpi.h>
15 #include <linux/acpi_io.h>
16 #include <acpi/acpiosxf.h>
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.
25 unsigned long phys_start;
29 struct list_head node;
32 static LIST_HEAD(nvs_list);
35 * suspend_nvs_register - register platform NVS memory region to save
36 * @start - physical address of the region
37 * @size - size of the region
39 * The NVS region need not be page-aligned (both ends) and we arrange
40 * things so that the data from page-aligned addresses in this region will
41 * be copied into separate RAM pages.
43 int suspend_nvs_register(unsigned long start, unsigned long size)
45 struct nvs_page *entry, *next;
48 unsigned int nr_bytes;
50 entry = kzalloc(sizeof(struct nvs_page), GFP_KERNEL);
54 list_add_tail(&entry->node, &nvs_list);
55 entry->phys_start = start;
56 nr_bytes = PAGE_SIZE - (start & ~PAGE_MASK);
57 entry->size = (size < nr_bytes) ? size : nr_bytes;
65 list_for_each_entry_safe(entry, next, &nvs_list, node) {
66 list_del(&entry->node);
73 * suspend_nvs_free - free data pages allocated for saving NVS regions
75 void suspend_nvs_free(void)
77 struct nvs_page *entry;
79 list_for_each_entry(entry, &nvs_list, node)
81 free_page((unsigned long)entry->data);
84 iounmap(entry->kaddr);
91 * suspend_nvs_alloc - allocate memory necessary for saving NVS regions
93 int suspend_nvs_alloc(void)
95 struct nvs_page *entry;
97 list_for_each_entry(entry, &nvs_list, node) {
98 entry->data = (void *)__get_free_page(GFP_KERNEL);
108 * suspend_nvs_save - save NVS memory regions
110 int suspend_nvs_save(void)
112 struct nvs_page *entry;
114 printk(KERN_INFO "PM: Saving platform NVS memory\n");
116 list_for_each_entry(entry, &nvs_list, node)
118 entry->kaddr = acpi_os_ioremap(entry->phys_start,
124 memcpy(entry->data, entry->kaddr, entry->size);
131 * suspend_nvs_restore - restore NVS memory regions
133 * This function is going to be called with interrupts disabled, so it
134 * cannot iounmap the virtual addresses used to access the NVS region.
136 void suspend_nvs_restore(void)
138 struct nvs_page *entry;
140 printk(KERN_INFO "PM: Restoring platform NVS memory\n");
142 list_for_each_entry(entry, &nvs_list, node)
144 memcpy(entry->kaddr, entry->data, entry->size);