nvs.c

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/*
 * nvs.c - Routines for saving and restoring ACPI NVS memory region
 *
 * Copyright (C) 2008-2011 Rafael J. Wysocki <[email protected]>, 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>

/* ACPI NVS regions, APEI may use it */

struct nvs_region {
    __u64 phys_start;
    __u64 size;
    struct list_head node;
};

static LIST_HEAD(nvs_region_list);

#ifdef CONFIG_ACPI_SLEEP
static int suspend_nvs_register(unsigned long start, unsigned long size);
#else
static inline int suspend_nvs_register(unsigned long a, unsigned long b)
{
    return 0;
}
#endif

int acpi_nvs_register(__u64 start, __u64 size)
{
    struct nvs_region *region;

    region = kmalloc(sizeof(*region), GFP_KERNEL);
    if (!region)
        return -ENOMEM;
    region->phys_start = start;
    region->size = size;
    list_add_tail(&region->node, &nvs_region_list);

    return suspend_nvs_register(start, size);
}

int acpi_nvs_for_each_region(int (*func)(__u64 start, __u64 size, void *data),
                 void *data)
{
    int rc;
    struct nvs_region *region;

    list_for_each_entry(region, &nvs_region_list, node) {
        rc = func(region->phys_start, region->size, data);
        if (rc)
            return rc;
    }

    return 0;
}


#ifdef CONFIG_ACPI_SLEEP
/*
 * 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);

static int suspend_nvs_register(unsigned long start, unsigned long size)
{
    struct nvs_page *entry, *next;

    pr_info("PM: Registering ACPI NVS region [mem %#010lx-%#010lx] (%ld bytes)\n",
        start, start + size - 1, 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;
}

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;
            }
        }
}

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;
}

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;
}

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);
}
#endif