// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2025, Intel Corporation.
 *
 * Memory Range and Region Mapping (MRRM) structure
 *
 * Parse and report the platform's MRRM table in /sys.
 */

#define pr_fmt(fmt) "acpi/mrrm: " fmt

#include <linux/acpi.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/sysfs.h>

/* Default assume one memory region covering all system memory, per the spec */
static int max_mem_region = 1;

/* Access for use by resctrl file system */
int acpi_mrrm_max_mem_region(void)
{
        return max_mem_region;
}

struct mrrm_mem_range_entry {
        u64 base;
        u64 length;
        int node;
        u8  local_region_id;
        u8  remote_region_id;
};

static struct mrrm_mem_range_entry *mrrm_mem_range_entry;
static u32 mrrm_mem_entry_num;

static int get_node_num(struct mrrm_mem_range_entry *e)
{
        unsigned int nid;

        for_each_online_node(nid) {
                for (int z = 0; z < MAX_NR_ZONES; z++) {
                        struct zone *zone = NODE_DATA(nid)->node_zones + z;

                        if (!populated_zone(zone))
                                continue;
                        if (zone_intersects(zone, PHYS_PFN(e->base), PHYS_PFN(e->length)))
                                return zone_to_nid(zone);
                }
        }

        return -ENOENT;
}

static __init int acpi_parse_mrrm(struct acpi_table_header *table)
{
        struct acpi_mrrm_mem_range_entry *mre_entry;
        struct acpi_table_mrrm *mrrm;
        void *mre, *mrrm_end;
        int mre_count = 0;

        mrrm = (struct acpi_table_mrrm *)table;
        if (!mrrm)
                return -ENODEV;

        if (mrrm->header.revision != 1)
                return -EINVAL;

        if (mrrm->flags & ACPI_MRRM_FLAGS_REGION_ASSIGNMENT_OS)
                return -EOPNOTSUPP;

        mrrm_end = (void *)mrrm + mrrm->header.length - 1;
        mre = (void *)mrrm + sizeof(struct acpi_table_mrrm);
        while (mre < mrrm_end) {
                mre_entry = mre;
                mre_count++;
                mre += mre_entry->header.length;
        }
        if (!mre_count) {
                pr_info(FW_BUG "No ranges listed in MRRM table\n");
                return -EINVAL;
        }

        mrrm_mem_range_entry = kmalloc_objs(*mrrm_mem_range_entry, mre_count,
                                            GFP_KERNEL | __GFP_ZERO);
        if (!mrrm_mem_range_entry)
                return -ENOMEM;

        mre = (void *)mrrm + sizeof(struct acpi_table_mrrm);
        while (mre < mrrm_end) {
                struct mrrm_mem_range_entry *e;

                mre_entry = mre;
                e = mrrm_mem_range_entry + mrrm_mem_entry_num;

                e->base = mre_entry->addr_base;
                e->length = mre_entry->addr_len;
                e->node = get_node_num(e);

                if (mre_entry->region_id_flags & ACPI_MRRM_VALID_REGION_ID_FLAGS_LOCAL)
                        e->local_region_id = mre_entry->local_region_id;
                else
                        e->local_region_id = -1;
                if (mre_entry->region_id_flags & ACPI_MRRM_VALID_REGION_ID_FLAGS_REMOTE)
                        e->remote_region_id = mre_entry->remote_region_id;
                else
                        e->remote_region_id = -1;

                mrrm_mem_entry_num++;
                mre += mre_entry->header.length;
        }

        max_mem_region = mrrm->max_mem_region;

        return 0;
}

#define RANGE_ATTR(name, fmt)                                           \
static ssize_t name##_show(struct kobject *kobj,                        \
                          struct kobj_attribute *attr, char *buf)       \
{                                                                       \
        struct mrrm_mem_range_entry *mre;                               \
        const char *kname = kobject_name(kobj);                         \
        int n, ret;                                                     \
                                                                        \
        ret = kstrtoint(kname + 5, 10, &n);                             \
        if (ret)                                                        \
                return ret;                                             \
                                                                        \
        mre = mrrm_mem_range_entry + n;                                 \
                                                                        \
        return sysfs_emit(buf, fmt, mre->name);                         \
}                                                                       \
static struct kobj_attribute name##_attr = __ATTR_RO(name)

RANGE_ATTR(base, "0x%llx\n");
RANGE_ATTR(length, "0x%llx\n");
RANGE_ATTR(node, "%d\n");
RANGE_ATTR(local_region_id, "%d\n");
RANGE_ATTR(remote_region_id, "%d\n");

static struct attribute *memory_range_attrs[] = {
        &base_attr.attr,
        &length_attr.attr,
        &node_attr.attr,
        &local_region_id_attr.attr,
        &remote_region_id_attr.attr,
        NULL
};

ATTRIBUTE_GROUPS(memory_range);

static __init int add_boot_memory_ranges(void)
{
        struct kobject *pkobj, *kobj, **kobjs;
        int ret = -EINVAL;
        char name[16];
        int i;

        pkobj = kobject_create_and_add("memory_ranges", acpi_kobj);
        if (!pkobj)
                return -ENOMEM;

        kobjs = kzalloc_objs(*kobjs, mrrm_mem_entry_num);
        if (!kobjs) {
                kobject_put(pkobj);
                return -ENOMEM;
        }

        for (i = 0; i < mrrm_mem_entry_num; i++) {
                scnprintf(name, sizeof(name), "range%d", i);
                kobj = kobject_create_and_add(name, pkobj);
                if (!kobj) {
                        ret = -ENOMEM;
                        goto cleanup;
                }

                ret = sysfs_create_groups(kobj, memory_range_groups);
                if (ret) {
                        kobject_put(kobj);
                        goto cleanup;
                }
                kobjs[i] = kobj;
        }

        kfree(kobjs);
        return 0;

cleanup:
        for (int j = 0; j < i; j++) {
                if (kobjs[j]) {
                        sysfs_remove_groups(kobjs[j], memory_range_groups);
                        kobject_put(kobjs[j]);
                }
        }
        kfree(kobjs);
        kobject_put(pkobj);
        return ret;
}

static __init int mrrm_init(void)
{
        int ret;

        ret = acpi_table_parse(ACPI_SIG_MRRM, acpi_parse_mrrm);
        if (ret < 0)
                return ret;

        return add_boot_memory_ranges();
}
device_initcall(mrrm_init);