linux/drivers/acpi/nvs.c
Rafael J. Wysocki bb45e394e2 ACPI / PM: Use existing ACPI iomaps for NVS save/restore (v2)
Modify the NVS save/restore code to use acpi_os_get_iomem() and
acpi_os_unmap_memory() to acquire and release references to ACPI
iomaps, respectively.  If there's no ACPI iomap corresponding to the
given NVS page, acpi_os_ioremap() is used to map that page and
iounmap() is used to unmap it during resume.  [If the page is not
present in the ACPI iomaps already, it doesn't make sense to add its
mapping to the list of ACPI iomaps, because it's going to be thrown
away during the subsequent resume anyway.]

Testing on my HP nx6325 shows that approx. 90% of the NVS pages
have already been mapped by ACPI before suspend and are present in
the ACPI iomaps, so this change appears to be the right thing to do
in general.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
2011-02-24 19:58:42 +01:00

161 lines
3.6 KiB
C

/*
* 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);
}