Root/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/* ACPI NVS regions, APEI may use it */
19
20struct nvs_region {
21    __u64 phys_start;
22    __u64 size;
23    struct list_head node;
24};
25
26static LIST_HEAD(nvs_region_list);
27
28#ifdef CONFIG_ACPI_SLEEP
29static int suspend_nvs_register(unsigned long start, unsigned long size);
30#else
31static inline int suspend_nvs_register(unsigned long a, unsigned long b)
32{
33    return 0;
34}
35#endif
36
37int 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
51int 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
74struct 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
83static 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 */
94static 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 */
129void 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_memory(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 */
153int 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 */
170int 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 */
202void 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
213

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