nvs.c revision 26fcaf60fe3861409eb4c455c5c0d0f00f599b08 
1/*
2 * linux/kernel/power/hibernate_nvs.c - Routines for handling NVS memory
3 *
4 * Copyright (C) 2008,2009 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/suspend.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
22struct nvs_page {
23	unsigned long phys_start;
24	unsigned int size;
25	void *kaddr;
26	void *data;
27	struct list_head node;
28};
29
30static 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 */
41int 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 */
73void 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 */
91int 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 */
108int 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 */
133void 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}
143