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/*
* nvs.c - Routines for saving and restoring ACPI NVS memory region
*
* Copyright (C) 2008-2011 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
*
* This file is released under the GPLv2.
*/
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/acpi.h>
#include <linux/acpi_io.h>
#include <acpi/acpiosxf.h>
/*
* Platforms, like ACPI, may want us to save some memory used by them during
* suspend and to restore the contents of this memory during the subsequent
* resume. The code below implements a mechanism allowing us to do that.
*/
struct nvs_page {
unsigned long phys_start;
unsigned int size;
void *kaddr;
void *data;
bool unmap;
struct list_head node;
};
static LIST_HEAD(nvs_list);
/**
* suspend_nvs_register - register platform NVS memory region to save
* @start - physical address of the region
* @size - size of the region
*
* The NVS region need not be page-aligned (both ends) and we arrange
* things so that the data from page-aligned addresses in this region will
* be copied into separate RAM pages.
*/
int suspend_nvs_register(unsigned long start, unsigned long size)
{
struct nvs_page *entry, *next;
pr_info("PM: Registering ACPI NVS region at %lx (%ld bytes)\n",
start, size);
while (size > 0) {
unsigned int nr_bytes;
entry = kzalloc(sizeof(struct nvs_page), GFP_KERNEL);
if (!entry)
goto Error;
list_add_tail(&entry->node, &nvs_list);
entry->phys_start = start;
nr_bytes = PAGE_SIZE - (start & ~PAGE_MASK);
entry->size = (size < nr_bytes) ? size : nr_bytes;
start += entry->size;
size -= entry->size;
}
return 0;
Error:
list_for_each_entry_safe(entry, next, &nvs_list, node) {
list_del(&entry->node);
kfree(entry);
}
return -ENOMEM;
}
/**
* suspend_nvs_free - free data pages allocated for saving NVS regions
*/
void suspend_nvs_free(void)
{
struct nvs_page *entry;
list_for_each_entry(entry, &nvs_list, node)
if (entry->data) {
free_page((unsigned long)entry->data);
entry->data = NULL;
if (entry->kaddr) {
if (entry->unmap) {
iounmap(entry->kaddr);
entry->unmap = false;
} else {
acpi_os_unmap_memory(entry->kaddr,
entry->size);
}
entry->kaddr = NULL;
}
}
}
/**
* suspend_nvs_alloc - allocate memory necessary for saving NVS regions
*/
int suspend_nvs_alloc(void)
{
struct nvs_page *entry;
list_for_each_entry(entry, &nvs_list, node) {
entry->data = (void *)__get_free_page(GFP_KERNEL);
if (!entry->data) {
suspend_nvs_free();
return -ENOMEM;
}
}
return 0;
}
/**
* suspend_nvs_save - save NVS memory regions
*/
int suspend_nvs_save(void)
{
struct nvs_page *entry;
printk(KERN_INFO "PM: Saving platform NVS memory\n");
list_for_each_entry(entry, &nvs_list, node)
if (entry->data) {
unsigned long phys = entry->phys_start;
unsigned int size = entry->size;
entry->kaddr = acpi_os_get_iomem(phys, size);
if (!entry->kaddr) {
entry->kaddr = acpi_os_ioremap(phys, size);
entry->unmap = !!entry->kaddr;
}
if (!entry->kaddr) {
suspend_nvs_free();
return -ENOMEM;
}
memcpy(entry->data, entry->kaddr, entry->size);
}
return 0;
}
/**
* suspend_nvs_restore - restore NVS memory regions
*
* This function is going to be called with interrupts disabled, so it
* cannot iounmap the virtual addresses used to access the NVS region.
*/
void suspend_nvs_restore(void)
{
struct nvs_page *entry;
printk(KERN_INFO "PM: Restoring platform NVS memory\n");
list_for_each_entry(entry, &nvs_list, node)
if (entry->data)
memcpy(entry->kaddr, entry->data, entry->size);
}
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