// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * pseries Memory Hotplug infrastructure.
 *
 * Copyright (C) 2008 Badari Pulavarty, IBM Corporation
 */

#define pr_fmt(fmt)     "pseries-hotplug-mem: " fmt

#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/memblock.h>
#include <linux/memory.h>
#include <linux/memory_hotplug.h>
#include <linux/slab.h>

#include <asm/firmware.h>
#include <asm/machdep.h>
#include <asm/prom.h>
#include <asm/sparsemem.h>
#include <asm/fadump.h>
#include <asm/drmem.h>
#include "pseries.h"

unsigned long pseries_memory_block_size(void)
{
        struct device_node *np;
        u64 memblock_size = MIN_MEMORY_BLOCK_SIZE;
        struct resource r;

        np = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
        if (np) {
                int len;
                int size_cells;
                const __be32 *prop;

                size_cells = of_n_size_cells(np);

                prop = of_get_property(np, "ibm,lmb-size", &len);
                if (prop && len >= size_cells * sizeof(__be32))
                        memblock_size = of_read_number(prop, size_cells);
                of_node_put(np);

        } else  if (machine_is(pseries)) {
                /* This fallback really only applies to pseries */
                unsigned int memzero_size = 0;

                np = of_find_node_by_path("/memory@0");
                if (np) {
                        if (!of_address_to_resource(np, 0, &r))
                                memzero_size = resource_size(&r);
                        of_node_put(np);
                }

                if (memzero_size) {
                        /* We now know the size of memory@0, use this to find
                         * the first memoryblock and get its size.
                         */
                        char buf[64];

                        sprintf(buf, "/memory@%x", memzero_size);
                        np = of_find_node_by_path(buf);
                        if (np) {
                                if (!of_address_to_resource(np, 0, &r))
                                        memblock_size = resource_size(&r);
                                of_node_put(np);
                        }
                }
        }
        return memblock_size;
}

static void dlpar_free_property(struct property *prop)
{
        kfree(prop->name);
        kfree(prop->value);
        kfree(prop);
}

static struct property *dlpar_clone_property(struct property *prop,
                                             u32 prop_size)
{
        struct property *new_prop;

        new_prop = kzalloc(sizeof(*new_prop), GFP_KERNEL);
        if (!new_prop)
                return NULL;

        new_prop->name = kstrdup(prop->name, GFP_KERNEL);
        new_prop->value = kzalloc(prop_size, GFP_KERNEL);
        if (!new_prop->name || !new_prop->value) {
                dlpar_free_property(new_prop);
                return NULL;
        }

        memcpy(new_prop->value, prop->value, prop->length);
        new_prop->length = prop_size;

        of_property_set_flag(new_prop, OF_DYNAMIC);
        return new_prop;
}

static bool find_aa_index(struct device_node *dr_node,
                         struct property *ala_prop,
                         const u32 *lmb_assoc, u32 *aa_index)
{
        u32 *assoc_arrays, new_prop_size;
        struct property *new_prop;
        int aa_arrays, aa_array_entries, aa_array_sz;
        int i, index;

        /*
         * The ibm,associativity-lookup-arrays property is defined to be
         * a 32-bit value specifying the number of associativity arrays
         * followed by a 32-bitvalue specifying the number of entries per
         * array, followed by the associativity arrays.
         */
        assoc_arrays = ala_prop->value;

        aa_arrays = be32_to_cpu(assoc_arrays[0]);
        aa_array_entries = be32_to_cpu(assoc_arrays[1]);
        aa_array_sz = aa_array_entries * sizeof(u32);

        for (i = 0; i < aa_arrays; i++) {
                index = (i * aa_array_entries) + 2;

                if (memcmp(&assoc_arrays[index], &lmb_assoc[1], aa_array_sz))
                        continue;

                *aa_index = i;
                return true;
        }

        new_prop_size = ala_prop->length + aa_array_sz;
        new_prop = dlpar_clone_property(ala_prop, new_prop_size);
        if (!new_prop)
                return false;

        assoc_arrays = new_prop->value;

        /* increment the number of entries in the lookup array */
        assoc_arrays[0] = cpu_to_be32(aa_arrays + 1);

        /* copy the new associativity into the lookup array */
        index = aa_arrays * aa_array_entries + 2;
        memcpy(&assoc_arrays[index], &lmb_assoc[1], aa_array_sz);

        of_update_property(dr_node, new_prop);

        /*
         * The associativity lookup array index for this lmb is
         * number of entries - 1 since we added its associativity
         * to the end of the lookup array.
         */
        *aa_index = be32_to_cpu(assoc_arrays[0]) - 1;
        return true;
}

static int update_lmb_associativity_index(struct drmem_lmb *lmb)
{
        struct device_node *parent, *lmb_node, *dr_node;
        struct property *ala_prop;
        const u32 *lmb_assoc;
        u32 aa_index;
        bool found;

        parent = of_find_node_by_path("/");
        if (!parent)
                return -ENODEV;

        lmb_node = dlpar_configure_connector(cpu_to_be32(lmb->drc_index),
                                             parent);
        of_node_put(parent);
        if (!lmb_node)
                return -EINVAL;

        lmb_assoc = of_get_property(lmb_node, "ibm,associativity", NULL);
        if (!lmb_assoc) {
                dlpar_free_cc_nodes(lmb_node);
                return -ENODEV;
        }

        update_numa_distance(lmb_node);

        dr_node = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
        if (!dr_node) {
                dlpar_free_cc_nodes(lmb_node);
                return -ENODEV;
        }

        ala_prop = of_find_property(dr_node, "ibm,associativity-lookup-arrays",
                                    NULL);
        if (!ala_prop) {
                of_node_put(dr_node);
                dlpar_free_cc_nodes(lmb_node);
                return -ENODEV;
        }

        found = find_aa_index(dr_node, ala_prop, lmb_assoc, &aa_index);

        of_node_put(dr_node);
        dlpar_free_cc_nodes(lmb_node);

        if (!found) {
                pr_err("Could not find LMB associativity\n");
                return -1;
        }

        lmb->aa_index = aa_index;
        return 0;
}

static struct memory_block *lmb_to_memblock(struct drmem_lmb *lmb)
{
        unsigned long section_nr;
        struct memory_block *mem_block;

        section_nr = pfn_to_section_nr(PFN_DOWN(lmb->base_addr));

        mem_block = find_memory_block(section_nr);
        return mem_block;
}

static int get_lmb_range(u32 drc_index, int n_lmbs,
                         struct drmem_lmb **start_lmb,
                         struct drmem_lmb **end_lmb)
{
        struct drmem_lmb *lmb, *start, *end;
        struct drmem_lmb *limit;

        start = NULL;
        for_each_drmem_lmb(lmb) {
                if (lmb->drc_index == drc_index) {
                        start = lmb;
                        break;
                }
        }

        if (!start)
                return -EINVAL;

        end = &start[n_lmbs];

        limit = &drmem_info->lmbs[drmem_info->n_lmbs];
        if (end > limit)
                return -EINVAL;

        *start_lmb = start;
        *end_lmb = end;
        return 0;
}

static int dlpar_change_lmb_state(struct drmem_lmb *lmb, bool online)
{
        struct memory_block *mem_block;
        int rc;

        mem_block = lmb_to_memblock(lmb);
        if (!mem_block)
                return -EINVAL;

        if (online && mem_block->dev.offline)
                rc = device_online(&mem_block->dev);
        else if (!online && !mem_block->dev.offline)
                rc = device_offline(&mem_block->dev);
        else
                rc = 0;

        put_device(&mem_block->dev);

        return rc;
}

static int dlpar_online_lmb(struct drmem_lmb *lmb)
{
        return dlpar_change_lmb_state(lmb, true);
}

#ifdef CONFIG_MEMORY_HOTREMOVE
static int dlpar_offline_lmb(struct drmem_lmb *lmb)
{
        return dlpar_change_lmb_state(lmb, false);
}

static int pseries_remove_memblock(unsigned long base, unsigned long memblock_size)
{
        unsigned long block_sz, start_pfn;
        int sections_per_block;
        int i;

        start_pfn = base >> PAGE_SHIFT;

        lock_device_hotplug();

        if (!pfn_valid(start_pfn))
                goto out;

        block_sz = pseries_memory_block_size();
        sections_per_block = block_sz / MIN_MEMORY_BLOCK_SIZE;

        for (i = 0; i < sections_per_block; i++) {
                __remove_memory(base, MIN_MEMORY_BLOCK_SIZE);
                base += MIN_MEMORY_BLOCK_SIZE;
        }

out:
        /* Update memory regions for memory remove */
        memblock_remove(base, memblock_size);
        unlock_device_hotplug();
        return 0;
}

static int pseries_remove_mem_node(struct device_node *np)
{
        const __be32 *prop;
        unsigned long base;
        unsigned long lmb_size;
        int ret = -EINVAL;
        int addr_cells, size_cells;

        /*
         * Check to see if we are actually removing memory
         */
        if (!of_node_is_type(np, "memory"))
                return 0;

        /*
         * Find the base address and size of the memblock
         */
        prop = of_get_property(np, "reg", NULL);
        if (!prop)
                return ret;

        addr_cells = of_n_addr_cells(np);
        size_cells = of_n_size_cells(np);

        /*
         * "reg" property represents (addr,size) tuple.
         */
        base = of_read_number(prop, addr_cells);
        prop += addr_cells;
        lmb_size = of_read_number(prop, size_cells);

        pseries_remove_memblock(base, lmb_size);
        return 0;
}

static bool lmb_is_removable(struct drmem_lmb *lmb)
{
        if ((lmb->flags & DRCONF_MEM_RESERVED) ||
                !(lmb->flags & DRCONF_MEM_ASSIGNED))
                return false;

#ifdef CONFIG_FA_DUMP
        /*
         * Don't hot-remove memory that falls in fadump boot memory area
         * and memory that is reserved for capturing old kernel memory.
         */
        if (is_fadump_memory_area(lmb->base_addr, memory_block_size_bytes()))
                return false;
#endif
        /* device_offline() will determine if we can actually remove this lmb */
        return true;
}

static int dlpar_add_lmb(struct drmem_lmb *);

static int dlpar_remove_lmb(struct drmem_lmb *lmb)
{
        struct memory_block *mem_block;
        unsigned long block_sz;
        int rc;

        if (!lmb_is_removable(lmb))
                return -EINVAL;

        mem_block = lmb_to_memblock(lmb);
        if (mem_block == NULL)
                return -EINVAL;

        rc = dlpar_offline_lmb(lmb);
        if (rc) {
                put_device(&mem_block->dev);
                return rc;
        }

        block_sz = pseries_memory_block_size();

        __remove_memory(lmb->base_addr, block_sz);
        put_device(&mem_block->dev);

        /* Update memory regions for memory remove */
        memblock_remove(lmb->base_addr, block_sz);

        invalidate_lmb_associativity_index(lmb);
        lmb->flags &= ~DRCONF_MEM_ASSIGNED;

        return 0;
}

static int dlpar_memory_remove_by_count(u32 lmbs_to_remove)
{
        struct drmem_lmb *lmb;
        int lmbs_reserved = 0;
        int lmbs_available = 0;
        int rc;

        pr_info("Attempting to hot-remove %d LMB(s)\n", lmbs_to_remove);

        if (lmbs_to_remove == 0)
                return -EINVAL;

        /* Validate that there are enough LMBs to satisfy the request */
        for_each_drmem_lmb(lmb) {
                if (lmb_is_removable(lmb))
                        lmbs_available++;

                if (lmbs_available == lmbs_to_remove)
                        break;
        }

        if (lmbs_available < lmbs_to_remove) {
                pr_info("Not enough LMBs available (%d of %d) to satisfy request\n",
                        lmbs_available, lmbs_to_remove);
                return -EINVAL;
        }

        for_each_drmem_lmb(lmb) {
                rc = dlpar_remove_lmb(lmb);
                if (rc)
                        continue;

                /* Mark this lmb so we can add it later if all of the
                 * requested LMBs cannot be removed.
                 */
                drmem_mark_lmb_reserved(lmb);

                lmbs_reserved++;
                if (lmbs_reserved == lmbs_to_remove)
                        break;
        }

        if (lmbs_reserved != lmbs_to_remove) {
                pr_err("Memory hot-remove failed, adding LMB's back\n");

                for_each_drmem_lmb(lmb) {
                        if (!drmem_lmb_reserved(lmb))
                                continue;

                        rc = dlpar_add_lmb(lmb);
                        if (rc)
                                pr_err("Failed to add LMB back, drc index %x\n",
                                       lmb->drc_index);

                        drmem_remove_lmb_reservation(lmb);

                        lmbs_reserved--;
                        if (lmbs_reserved == 0)
                                break;
                }

                rc = -EINVAL;
        } else {
                for_each_drmem_lmb(lmb) {
                        if (!drmem_lmb_reserved(lmb))
                                continue;

                        dlpar_release_drc(lmb->drc_index);
                        pr_info("Memory at %llx was hot-removed\n",
                                lmb->base_addr);

                        drmem_remove_lmb_reservation(lmb);

                        lmbs_reserved--;
                        if (lmbs_reserved == 0)
                                break;
                }
                rc = 0;
        }

        return rc;
}

static int dlpar_memory_remove_by_index(u32 drc_index)
{
        struct drmem_lmb *lmb;
        int lmb_found;
        int rc;

        pr_debug("Attempting to hot-remove LMB, drc index %x\n", drc_index);

        lmb_found = 0;
        for_each_drmem_lmb(lmb) {
                if (lmb->drc_index == drc_index) {
                        lmb_found = 1;
                        rc = dlpar_remove_lmb(lmb);
                        if (!rc)
                                dlpar_release_drc(lmb->drc_index);

                        break;
                }
        }

        if (!lmb_found)
                rc = -EINVAL;

        if (rc)
                pr_debug("Failed to hot-remove memory at %llx\n",
                         lmb->base_addr);
        else
                pr_debug("Memory at %llx was hot-removed\n", lmb->base_addr);

        return rc;
}

static int dlpar_memory_remove_by_ic(u32 lmbs_to_remove, u32 drc_index)
{
        struct drmem_lmb *lmb, *start_lmb, *end_lmb;
        int rc;

        pr_info("Attempting to hot-remove %u LMB(s) at %x\n",
                lmbs_to_remove, drc_index);

        if (lmbs_to_remove == 0)
                return -EINVAL;

        rc = get_lmb_range(drc_index, lmbs_to_remove, &start_lmb, &end_lmb);
        if (rc)
                return -EINVAL;

        /*
         * Validate that all LMBs in range are not reserved. Note that it
         * is ok if they are !ASSIGNED since our goal here is to remove the
         * LMB range, regardless of whether some LMBs were already removed
         * by any other reason.
         *
         * This is a contrast to what is done in remove_by_count() where we
         * check for both RESERVED and !ASSIGNED (via lmb_is_removable()),
         * because we want to remove a fixed amount of LMBs in that function.
         */
        for_each_drmem_lmb_in_range(lmb, start_lmb, end_lmb) {
                if (lmb->flags & DRCONF_MEM_RESERVED) {
                        pr_err("Memory at %llx (drc index %x) is reserved\n",
                                lmb->base_addr, lmb->drc_index);
                        return -EINVAL;
                }
        }

        for_each_drmem_lmb_in_range(lmb, start_lmb, end_lmb) {
                /*
                 * dlpar_remove_lmb() will error out if the LMB is already
                 * !ASSIGNED, but this case is a no-op for us.
                 */
                if (!(lmb->flags & DRCONF_MEM_ASSIGNED))
                        continue;

                rc = dlpar_remove_lmb(lmb);
                if (rc)
                        break;

                drmem_mark_lmb_reserved(lmb);
        }

        if (rc) {
                pr_err("Memory indexed-count-remove failed, adding any removed LMBs\n");


                for_each_drmem_lmb_in_range(lmb, start_lmb, end_lmb) {
                        if (!drmem_lmb_reserved(lmb))
                                continue;

                        /*
                         * Setting the isolation state of an UNISOLATED/CONFIGURED
                         * device to UNISOLATE is a no-op, but the hypervisor can
                         * use it as a hint that the LMB removal failed.
                         */
                        dlpar_unisolate_drc(lmb->drc_index);

                        rc = dlpar_add_lmb(lmb);
                        if (rc)
                                pr_err("Failed to add LMB, drc index %x\n",
                                       lmb->drc_index);

                        drmem_remove_lmb_reservation(lmb);
                }
                rc = -EINVAL;
        } else {
                for_each_drmem_lmb_in_range(lmb, start_lmb, end_lmb) {
                        if (!drmem_lmb_reserved(lmb))
                                continue;

                        dlpar_release_drc(lmb->drc_index);
                        pr_info("Memory at %llx (drc index %x) was hot-removed\n",
                                lmb->base_addr, lmb->drc_index);

                        drmem_remove_lmb_reservation(lmb);
                }
        }

        return rc;
}

#else
static inline int pseries_remove_memblock(unsigned long base,
                                          unsigned long memblock_size)
{
        return -EOPNOTSUPP;
}
static inline int pseries_remove_mem_node(struct device_node *np)
{
        return 0;
}
static int dlpar_remove_lmb(struct drmem_lmb *lmb)
{
        return -EOPNOTSUPP;
}
static int dlpar_memory_remove_by_count(u32 lmbs_to_remove)
{
        return -EOPNOTSUPP;
}
static int dlpar_memory_remove_by_index(u32 drc_index)
{
        return -EOPNOTSUPP;
}

static int dlpar_memory_remove_by_ic(u32 lmbs_to_remove, u32 drc_index)
{
        return -EOPNOTSUPP;
}
#endif /* CONFIG_MEMORY_HOTREMOVE */

static int dlpar_add_lmb(struct drmem_lmb *lmb)
{
        unsigned long block_sz;
        int nid, rc;

        if (lmb->flags & DRCONF_MEM_ASSIGNED)
                return -EINVAL;

        rc = update_lmb_associativity_index(lmb);
        if (rc) {
                dlpar_release_drc(lmb->drc_index);
                return rc;
        }

        block_sz = memory_block_size_bytes();

        /* Find the node id for this LMB.  Fake one if necessary. */
        nid = of_drconf_to_nid_single(lmb);
        if (nid < 0 || !node_possible(nid))
                nid = first_online_node;

        /* Add the memory */
        rc = __add_memory(nid, lmb->base_addr, block_sz, MHP_NONE);
        if (rc) {
                invalidate_lmb_associativity_index(lmb);
                return rc;
        }

        rc = dlpar_online_lmb(lmb);
        if (rc) {
                __remove_memory(lmb->base_addr, block_sz);
                invalidate_lmb_associativity_index(lmb);
        } else {
                lmb->flags |= DRCONF_MEM_ASSIGNED;
        }

        return rc;
}

static int dlpar_memory_add_by_count(u32 lmbs_to_add)
{
        struct drmem_lmb *lmb;
        int lmbs_available = 0;
        int lmbs_reserved = 0;
        int rc;

        pr_info("Attempting to hot-add %d LMB(s)\n", lmbs_to_add);

        if (lmbs_to_add == 0)
                return -EINVAL;

        /* Validate that there are enough LMBs to satisfy the request */
        for_each_drmem_lmb(lmb) {
                if (lmb->flags & DRCONF_MEM_RESERVED)
                        continue;

                if (!(lmb->flags & DRCONF_MEM_ASSIGNED))
                        lmbs_available++;

                if (lmbs_available == lmbs_to_add)
                        break;
        }

        if (lmbs_available < lmbs_to_add)
                return -EINVAL;

        for_each_drmem_lmb(lmb) {
                if (lmb->flags & DRCONF_MEM_ASSIGNED)
                        continue;

                rc = dlpar_acquire_drc(lmb->drc_index);
                if (rc)
                        continue;

                rc = dlpar_add_lmb(lmb);
                if (rc) {
                        dlpar_release_drc(lmb->drc_index);
                        continue;
                }

                /* Mark this lmb so we can remove it later if all of the
                 * requested LMBs cannot be added.
                 */
                drmem_mark_lmb_reserved(lmb);
                lmbs_reserved++;
                if (lmbs_reserved == lmbs_to_add)
                        break;
        }

        if (lmbs_reserved != lmbs_to_add) {
                pr_err("Memory hot-add failed, removing any added LMBs\n");

                for_each_drmem_lmb(lmb) {
                        if (!drmem_lmb_reserved(lmb))
                                continue;

                        rc = dlpar_remove_lmb(lmb);
                        if (rc)
                                pr_err("Failed to remove LMB, drc index %x\n",
                                       lmb->drc_index);
                        else
                                dlpar_release_drc(lmb->drc_index);

                        drmem_remove_lmb_reservation(lmb);
                        lmbs_reserved--;

                        if (lmbs_reserved == 0)
                                break;
                }
                rc = -EINVAL;
        } else {
                for_each_drmem_lmb(lmb) {
                        if (!drmem_lmb_reserved(lmb))
                                continue;

                        pr_debug("Memory at %llx (drc index %x) was hot-added\n",
                                 lmb->base_addr, lmb->drc_index);
                        drmem_remove_lmb_reservation(lmb);
                        lmbs_reserved--;

                        if (lmbs_reserved == 0)
                                break;
                }
                rc = 0;
        }

        return rc;
}

static int dlpar_memory_add_by_index(u32 drc_index)
{
        struct drmem_lmb *lmb;
        int rc, lmb_found;

        pr_info("Attempting to hot-add LMB, drc index %x\n", drc_index);

        lmb_found = 0;
        for_each_drmem_lmb(lmb) {
                if (lmb->drc_index == drc_index) {
                        lmb_found = 1;
                        rc = dlpar_acquire_drc(lmb->drc_index);
                        if (!rc) {
                                rc = dlpar_add_lmb(lmb);
                                if (rc)
                                        dlpar_release_drc(lmb->drc_index);
                        }

                        break;
                }
        }

        if (!lmb_found)
                rc = -EINVAL;

        if (rc)
                pr_info("Failed to hot-add memory, drc index %x\n", drc_index);
        else
                pr_info("Memory at %llx (drc index %x) was hot-added\n",
                        lmb->base_addr, drc_index);

        return rc;
}

static int dlpar_memory_add_by_ic(u32 lmbs_to_add, u32 drc_index)
{
        struct drmem_lmb *lmb, *start_lmb, *end_lmb;
        int rc;

        pr_info("Attempting to hot-add %u LMB(s) at index %x\n",
                lmbs_to_add, drc_index);

        if (lmbs_to_add == 0)
                return -EINVAL;

        rc = get_lmb_range(drc_index, lmbs_to_add, &start_lmb, &end_lmb);
        if (rc)
                return -EINVAL;

        /* Validate that the LMBs in this range are not reserved */
        for_each_drmem_lmb_in_range(lmb, start_lmb, end_lmb) {
                /* Fail immediately if the whole range can't be hot-added */
                if (lmb->flags & DRCONF_MEM_RESERVED) {
                        pr_err("Memory at %llx (drc index %x) is reserved\n",
                                        lmb->base_addr, lmb->drc_index);
                        return -EINVAL;
                }
        }

        for_each_drmem_lmb_in_range(lmb, start_lmb, end_lmb) {
                if (lmb->flags & DRCONF_MEM_ASSIGNED)
                        continue;

                rc = dlpar_acquire_drc(lmb->drc_index);
                if (rc)
                        break;

                rc = dlpar_add_lmb(lmb);
                if (rc) {
                        dlpar_release_drc(lmb->drc_index);
                        break;
                }

                drmem_mark_lmb_reserved(lmb);
        }

        if (rc) {
                pr_err("Memory indexed-count-add failed, removing any added LMBs\n");

                for_each_drmem_lmb_in_range(lmb, start_lmb, end_lmb) {
                        if (!drmem_lmb_reserved(lmb))
                                continue;

                        rc = dlpar_remove_lmb(lmb);
                        if (rc)
                                pr_err("Failed to remove LMB, drc index %x\n",
                                       lmb->drc_index);
                        else
                                dlpar_release_drc(lmb->drc_index);

                        drmem_remove_lmb_reservation(lmb);
                }
                rc = -EINVAL;
        } else {
                for_each_drmem_lmb_in_range(lmb, start_lmb, end_lmb) {
                        if (!drmem_lmb_reserved(lmb))
                                continue;

                        pr_info("Memory at %llx (drc index %x) was hot-added\n",
                                lmb->base_addr, lmb->drc_index);
                        drmem_remove_lmb_reservation(lmb);
                }
        }

        return rc;
}

int dlpar_memory(struct pseries_hp_errorlog *hp_elog)
{
        u32 count, drc_index;
        int rc;

        lock_device_hotplug();

        switch (hp_elog->action) {
        case PSERIES_HP_ELOG_ACTION_ADD:
                switch (hp_elog->id_type) {
                case PSERIES_HP_ELOG_ID_DRC_COUNT:
                        count = hp_elog->_drc_u.drc_count;
                        rc = dlpar_memory_add_by_count(count);
                        break;
                case PSERIES_HP_ELOG_ID_DRC_INDEX:
                        drc_index = hp_elog->_drc_u.drc_index;
                        rc = dlpar_memory_add_by_index(drc_index);
                        break;
                case PSERIES_HP_ELOG_ID_DRC_IC:
                        count = hp_elog->_drc_u.ic.count;
                        drc_index = hp_elog->_drc_u.ic.index;
                        rc = dlpar_memory_add_by_ic(count, drc_index);
                        break;
                default:
                        rc = -EINVAL;
                        break;
                }

                break;
        case PSERIES_HP_ELOG_ACTION_REMOVE:
                switch (hp_elog->id_type) {
                case PSERIES_HP_ELOG_ID_DRC_COUNT:
                        count = hp_elog->_drc_u.drc_count;
                        rc = dlpar_memory_remove_by_count(count);
                        break;
                case PSERIES_HP_ELOG_ID_DRC_INDEX:
                        drc_index = hp_elog->_drc_u.drc_index;
                        rc = dlpar_memory_remove_by_index(drc_index);
                        break;
                case PSERIES_HP_ELOG_ID_DRC_IC:
                        count = hp_elog->_drc_u.ic.count;
                        drc_index = hp_elog->_drc_u.ic.index;
                        rc = dlpar_memory_remove_by_ic(count, drc_index);
                        break;
                default:
                        rc = -EINVAL;
                        break;
                }

                break;
        default:
                pr_err("Invalid action (%d) specified\n", hp_elog->action);
                rc = -EINVAL;
                break;
        }

        if (!rc)
                rc = drmem_update_dt();

        unlock_device_hotplug();
        return rc;
}

static int pseries_add_mem_node(struct device_node *np)
{
        const __be32 *prop;
        unsigned long base;
        unsigned long lmb_size;
        int ret = -EINVAL;
        int addr_cells, size_cells;

        /*
         * Check to see if we are actually adding memory
         */
        if (!of_node_is_type(np, "memory"))
                return 0;

        /*
         * Find the base and size of the memblock
         */
        prop = of_get_property(np, "reg", NULL);
        if (!prop)
                return ret;

        addr_cells = of_n_addr_cells(np);
        size_cells = of_n_size_cells(np);
        /*
         * "reg" property represents (addr,size) tuple.
         */
        base = of_read_number(prop, addr_cells);
        prop += addr_cells;
        lmb_size = of_read_number(prop, size_cells);

        /*
         * Update memory region to represent the memory add
         */
        ret = memblock_add(base, lmb_size);
        return (ret < 0) ? -EINVAL : 0;
}

static int pseries_memory_notifier(struct notifier_block *nb,
                                   unsigned long action, void *data)
{
        struct of_reconfig_data *rd = data;
        int err = 0;

        switch (action) {
        case OF_RECONFIG_ATTACH_NODE:
                err = pseries_add_mem_node(rd->dn);
                break;
        case OF_RECONFIG_DETACH_NODE:
                err = pseries_remove_mem_node(rd->dn);
                break;
        case OF_RECONFIG_UPDATE_PROPERTY:
                if (!strcmp(rd->dn->name,
                            "ibm,dynamic-reconfiguration-memory"))
                        drmem_update_lmbs(rd->prop);
        }
        return notifier_from_errno(err);
}

static struct notifier_block pseries_mem_nb = {
        .notifier_call = pseries_memory_notifier,
};

static int __init pseries_memory_hotplug_init(void)
{
        if (firmware_has_feature(FW_FEATURE_LPAR))
                of_reconfig_notifier_register(&pseries_mem_nb);

        return 0;
}
machine_device_initcall(pseries, pseries_memory_hotplug_init);