// SPDX-License-Identifier: GPL-2.0-only
/*
 * nvs.c - Routines for saving and restoring ACPI NVS memory region
 *
 * Copyright (C) 2008-2011 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
 */

#define pr_fmt(fmt) "ACPI: PM: " fmt

#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 "internal.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);

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

        pr_info("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;
}

/**
 * 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_iomem(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;

        pr_info("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;

        pr_info("Restoring platform NVS memory\n");

        list_for_each_entry(entry, &nvs_list, node)
                if (entry->data)
                        memcpy(entry->kaddr, entry->data, entry->size);
}
#endif