Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

[linux/fpc-iii.git] / arch / powerpc / mm / numa.c

/*
 * pSeries NUMA support
 *
 * Copyright (C) 2002 Anton Blanchard <anton@au.ibm.com>, IBM
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */
#include <linux/threads.h>
#include <linux/bootmem.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/mmzone.h>
#include <linux/export.h>
#include <linux/nodemask.h>
#include <linux/cpu.h>
#include <linux/notifier.h>
#include <linux/memblock.h>
#include <linux/of.h>
#include <linux/pfn.h>
#include <linux/cpuset.h>
#include <linux/node.h>
#include <linux/stop_machine.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
#include <asm/cputhreads.h>
#include <asm/sparsemem.h>
#include <asm/prom.h>
#include <asm/smp.h>
#include <asm/cputhreads.h>
#include <asm/topology.h>
#include <asm/firmware.h>
#include <asm/paca.h>
#include <asm/hvcall.h>
#include <asm/setup.h>
#include <asm/vdso.h>

static int numa_enabled = 1;

static char *cmdline __initdata;

static int numa_debug;
#define dbg(args...) if (numa_debug) { printk(KERN_INFO args); }

int numa_cpu_lookup_table[NR_CPUS];
cpumask_var_t node_to_cpumask_map[MAX_NUMNODES];
struct pglist_data *node_data[MAX_NUMNODES];

EXPORT_SYMBOL(numa_cpu_lookup_table);
EXPORT_SYMBOL(node_to_cpumask_map);
EXPORT_SYMBOL(node_data);

static int min_common_depth;
static int n_mem_addr_cells, n_mem_size_cells;
static int form1_affinity;

#define MAX_DISTANCE_REF_POINTS 4
static int distance_ref_points_depth;
static const __be32 *distance_ref_points;
static int distance_lookup_table[MAX_NUMNODES][MAX_DISTANCE_REF_POINTS];

/*
 * Allocate node_to_cpumask_map based on number of available nodes
 * Requires node_possible_map to be valid.
 *
 * Note: cpumask_of_node() is not valid until after this is done.
 */
static void __init setup_node_to_cpumask_map(void)
{
        unsigned int node;

        /* setup nr_node_ids if not done yet */
        if (nr_node_ids == MAX_NUMNODES)
                setup_nr_node_ids();

        /* allocate the map */
        for (node = 0; node < nr_node_ids; node++)
                alloc_bootmem_cpumask_var(&node_to_cpumask_map[node]);

        /* cpumask_of_node() will now work */
        dbg("Node to cpumask map for %d nodes\n", nr_node_ids);
}

static int __init fake_numa_create_new_node(unsigned long end_pfn,
                                                unsigned int *nid)
{
        unsigned long long mem;
        char *p = cmdline;
        static unsigned int fake_nid;
        static unsigned long long curr_boundary;

        /*
         * Modify node id, iff we started creating NUMA nodes
         * We want to continue from where we left of the last time
         */
        if (fake_nid)
                *nid = fake_nid;
        /*
         * In case there are no more arguments to parse, the
         * node_id should be the same as the last fake node id
         * (we've handled this above).
         */
        if (!p)
                return 0;

        mem = memparse(p, &p);
        if (!mem)
                return 0;

        if (mem < curr_boundary)
                return 0;

        curr_boundary = mem;

        if ((end_pfn << PAGE_SHIFT) > mem) {
                /*
                 * Skip commas and spaces
                 */
                while (*p == ',' || *p == ' ' || *p == '\t')
                        p++;

                cmdline = p;
                fake_nid++;
                *nid = fake_nid;
                dbg("created new fake_node with id %d\n", fake_nid);
                return 1;
        }
        return 0;
}

/*
 * get_node_active_region - Return active region containing pfn
 * Active range returned is empty if none found.
 * @pfn: The page to return the region for
 * @node_ar: Returned set to the active region containing @pfn
 */
static void __init get_node_active_region(unsigned long pfn,
                                          struct node_active_region *node_ar)
{
        unsigned long start_pfn, end_pfn;
        int i, nid;

        for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, &nid) {
                if (pfn >= start_pfn && pfn < end_pfn) {
                        node_ar->nid = nid;
                        node_ar->start_pfn = start_pfn;
                        node_ar->end_pfn = end_pfn;
                        break;
                }
        }
}

static void reset_numa_cpu_lookup_table(void)
{
        unsigned int cpu;

        for_each_possible_cpu(cpu)
                numa_cpu_lookup_table[cpu] = -1;
}

static void update_numa_cpu_lookup_table(unsigned int cpu, int node)
{
        numa_cpu_lookup_table[cpu] = node;
}

static void map_cpu_to_node(int cpu, int node)
{
        update_numa_cpu_lookup_table(cpu, node);

        dbg("adding cpu %d to node %d\n", cpu, node);

        if (!(cpumask_test_cpu(cpu, node_to_cpumask_map[node])))
                cpumask_set_cpu(cpu, node_to_cpumask_map[node]);
}

#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_PPC_SPLPAR)
static void unmap_cpu_from_node(unsigned long cpu)
{
        int node = numa_cpu_lookup_table[cpu];

        dbg("removing cpu %lu from node %d\n", cpu, node);

        if (cpumask_test_cpu(cpu, node_to_cpumask_map[node])) {
                cpumask_clear_cpu(cpu, node_to_cpumask_map[node]);
        } else {
                printk(KERN_ERR "WARNING: cpu %lu not found in node %d\n",
                       cpu, node);
        }
}
#endif /* CONFIG_HOTPLUG_CPU || CONFIG_PPC_SPLPAR */

/* must hold reference to node during call */
static const __be32 *of_get_associativity(struct device_node *dev)
{
        return of_get_property(dev, "ibm,associativity", NULL);
}

/*
 * Returns the property linux,drconf-usable-memory if
 * it exists (the property exists only in kexec/kdump kernels,
 * added by kexec-tools)
 */
static const __be32 *of_get_usable_memory(struct device_node *memory)
{
        const __be32 *prop;
        u32 len;
        prop = of_get_property(memory, "linux,drconf-usable-memory", &len);
        if (!prop || len < sizeof(unsigned int))
                return NULL;
        return prop;
}

int __node_distance(int a, int b)
{
        int i;
        int distance = LOCAL_DISTANCE;

        if (!form1_affinity)
                return ((a == b) ? LOCAL_DISTANCE : REMOTE_DISTANCE);

        for (i = 0; i < distance_ref_points_depth; i++) {
                if (distance_lookup_table[a][i] == distance_lookup_table[b][i])
                        break;

                /* Double the distance for each NUMA level */
                distance *= 2;
        }

        return distance;
}

static void initialize_distance_lookup_table(int nid,
                const __be32 *associativity)
{
        int i;

        if (!form1_affinity)
                return;

        for (i = 0; i < distance_ref_points_depth; i++) {
                const __be32 *entry;

                entry = &associativity[be32_to_cpu(distance_ref_points[i])];
                distance_lookup_table[nid][i] = of_read_number(entry, 1);
        }
}

/* Returns nid in the range [0..MAX_NUMNODES-1], or -1 if no useful numa
 * info is found.
 */
static int associativity_to_nid(const __be32 *associativity)
{
        int nid = -1;

        if (min_common_depth == -1)
                goto out;

        if (of_read_number(associativity, 1) >= min_common_depth)
                nid = of_read_number(&associativity[min_common_depth], 1);

        /* POWER4 LPAR uses 0xffff as invalid node */
        if (nid == 0xffff || nid >= MAX_NUMNODES)
                nid = -1;

        if (nid > 0 &&
            of_read_number(associativity, 1) >= distance_ref_points_depth)
                initialize_distance_lookup_table(nid, associativity);

out:
        return nid;
}

/* Returns the nid associated with the given device tree node,
 * or -1 if not found.
 */
static int of_node_to_nid_single(struct device_node *device)
{
        int nid = -1;
        const __be32 *tmp;

        tmp = of_get_associativity(device);
        if (tmp)
                nid = associativity_to_nid(tmp);
        return nid;
}

/* Walk the device tree upwards, looking for an associativity id */
int of_node_to_nid(struct device_node *device)
{
        struct device_node *tmp;
        int nid = -1;

        of_node_get(device);
        while (device) {
                nid = of_node_to_nid_single(device);
                if (nid != -1)
                        break;

                tmp = device;
                device = of_get_parent(tmp);
                of_node_put(tmp);
        }
        of_node_put(device);

        return nid;
}
EXPORT_SYMBOL_GPL(of_node_to_nid);

static int __init find_min_common_depth(void)
{
        int depth;
        struct device_node *root;

        if (firmware_has_feature(FW_FEATURE_OPAL))
                root = of_find_node_by_path("/ibm,opal");
        else
                root = of_find_node_by_path("/rtas");
        if (!root)
                root = of_find_node_by_path("/");

        /*
         * This property is a set of 32-bit integers, each representing
         * an index into the ibm,associativity nodes.
         *
         * With form 0 affinity the first integer is for an SMP configuration
         * (should be all 0's) and the second is for a normal NUMA
         * configuration. We have only one level of NUMA.
         *
         * With form 1 affinity the first integer is the most significant
         * NUMA boundary and the following are progressively less significant
         * boundaries. There can be more than one level of NUMA.
         */
        distance_ref_points = of_get_property(root,
                                        "ibm,associativity-reference-points",
                                        &distance_ref_points_depth);

        if (!distance_ref_points) {
                dbg("NUMA: ibm,associativity-reference-points not found.\n");
                goto err;
        }

        distance_ref_points_depth /= sizeof(int);

        if (firmware_has_feature(FW_FEATURE_OPAL) ||
            firmware_has_feature(FW_FEATURE_TYPE1_AFFINITY)) {
                dbg("Using form 1 affinity\n");
                form1_affinity = 1;
        }

        if (form1_affinity) {
                depth = of_read_number(distance_ref_points, 1);
        } else {
                if (distance_ref_points_depth < 2) {
                        printk(KERN_WARNING "NUMA: "
                                "short ibm,associativity-reference-points\n");
                        goto err;
                }

                depth = of_read_number(&distance_ref_points[1], 1);
        }

        /*
         * Warn and cap if the hardware supports more than
         * MAX_DISTANCE_REF_POINTS domains.
         */
        if (distance_ref_points_depth > MAX_DISTANCE_REF_POINTS) {
                printk(KERN_WARNING "NUMA: distance array capped at "
                        "%d entries\n", MAX_DISTANCE_REF_POINTS);
                distance_ref_points_depth = MAX_DISTANCE_REF_POINTS;
        }

        of_node_put(root);
        return depth;

err:
        of_node_put(root);
        return -1;
}

static void __init get_n_mem_cells(int *n_addr_cells, int *n_size_cells)
{
        struct device_node *memory = NULL;

        memory = of_find_node_by_type(memory, "memory");
        if (!memory)
                panic("numa.c: No memory nodes found!");

        *n_addr_cells = of_n_addr_cells(memory);
        *n_size_cells = of_n_size_cells(memory);
        of_node_put(memory);
}

static unsigned long read_n_cells(int n, const __be32 **buf)
{
        unsigned long result = 0;

        while (n--) {
                result = (result << 32) | of_read_number(*buf, 1);
                (*buf)++;
        }
        return result;
}

/*
 * Read the next memblock list entry from the ibm,dynamic-memory property
 * and return the information in the provided of_drconf_cell structure.
 */
static void read_drconf_cell(struct of_drconf_cell *drmem, const __be32 **cellp)
{
        const __be32 *cp;

        drmem->base_addr = read_n_cells(n_mem_addr_cells, cellp);

        cp = *cellp;
        drmem->drc_index = of_read_number(cp, 1);
        drmem->reserved = of_read_number(&cp[1], 1);
        drmem->aa_index = of_read_number(&cp[2], 1);
        drmem->flags = of_read_number(&cp[3], 1);

        *cellp = cp + 4;
}

/*
 * Retrieve and validate the ibm,dynamic-memory property of the device tree.
 *
 * The layout of the ibm,dynamic-memory property is a number N of memblock
 * list entries followed by N memblock list entries.  Each memblock list entry
 * contains information as laid out in the of_drconf_cell struct above.
 */
static int of_get_drconf_memory(struct device_node *memory, const __be32 **dm)
{
        const __be32 *prop;
        u32 len, entries;

        prop = of_get_property(memory, "ibm,dynamic-memory", &len);
        if (!prop || len < sizeof(unsigned int))
                return 0;

        entries = of_read_number(prop++, 1);

        /* Now that we know the number of entries, revalidate the size
         * of the property read in to ensure we have everything
         */
        if (len < (entries * (n_mem_addr_cells + 4) + 1) * sizeof(unsigned int))
                return 0;

        *dm = prop;
        return entries;
}

/*
 * Retrieve and validate the ibm,lmb-size property for drconf memory
 * from the device tree.
 */
static u64 of_get_lmb_size(struct device_node *memory)
{
        const __be32 *prop;
        u32 len;

        prop = of_get_property(memory, "ibm,lmb-size", &len);
        if (!prop || len < sizeof(unsigned int))
                return 0;

        return read_n_cells(n_mem_size_cells, &prop);
}

struct assoc_arrays {
        u32     n_arrays;
        u32     array_sz;
        const __be32 *arrays;
};

/*
 * Retrieve and validate the list of associativity arrays for drconf
 * memory from the ibm,associativity-lookup-arrays property of the
 * device tree..
 *
 * The layout of the ibm,associativity-lookup-arrays property is a number N
 * indicating the number of associativity arrays, followed by a number M
 * indicating the size of each associativity array, followed by a list
 * of N associativity arrays.
 */
static int of_get_assoc_arrays(struct device_node *memory,
                               struct assoc_arrays *aa)
{
        const __be32 *prop;
        u32 len;

        prop = of_get_property(memory, "ibm,associativity-lookup-arrays", &len);
        if (!prop || len < 2 * sizeof(unsigned int))
                return -1;

        aa->n_arrays = of_read_number(prop++, 1);
        aa->array_sz = of_read_number(prop++, 1);

        /* Now that we know the number of arrays and size of each array,
         * revalidate the size of the property read in.
         */
        if (len < (aa->n_arrays * aa->array_sz + 2) * sizeof(unsigned int))
                return -1;

        aa->arrays = prop;
        return 0;
}

/*
 * This is like of_node_to_nid_single() for memory represented in the
 * ibm,dynamic-reconfiguration-memory node.
 */
static int of_drconf_to_nid_single(struct of_drconf_cell *drmem,
                                   struct assoc_arrays *aa)
{
        int default_nid = 0;
        int nid = default_nid;
        int index;

        if (min_common_depth > 0 && min_common_depth <= aa->array_sz &&
            !(drmem->flags & DRCONF_MEM_AI_INVALID) &&
            drmem->aa_index < aa->n_arrays) {
                index = drmem->aa_index * aa->array_sz + min_common_depth - 1;
                nid = of_read_number(&aa->arrays[index], 1);

                if (nid == 0xffff || nid >= MAX_NUMNODES)
                        nid = default_nid;
        }

        return nid;
}

/*
 * Figure out to which domain a cpu belongs and stick it there.
 * Return the id of the domain used.
 */
static int numa_setup_cpu(unsigned long lcpu)
{
        int nid;
        struct device_node *cpu;

        /*
         * If a valid cpu-to-node mapping is already available, use it
         * directly instead of querying the firmware, since it represents
         * the most recent mapping notified to us by the platform (eg: VPHN).
         */
        if ((nid = numa_cpu_lookup_table[lcpu]) >= 0) {
                map_cpu_to_node(lcpu, nid);
                return nid;
        }

        cpu = of_get_cpu_node(lcpu, NULL);

        if (!cpu) {
                WARN_ON(1);
                nid = 0;
                goto out;
        }

        nid = of_node_to_nid_single(cpu);

        if (nid < 0 || !node_online(nid))
                nid = first_online_node;
out:
        map_cpu_to_node(lcpu, nid);

        of_node_put(cpu);

        return nid;
}

static void verify_cpu_node_mapping(int cpu, int node)
{
        int base, sibling, i;

        /* Verify that all the threads in the core belong to the same node */
        base = cpu_first_thread_sibling(cpu);

        for (i = 0; i < threads_per_core; i++) {
                sibling = base + i;

                if (sibling == cpu || cpu_is_offline(sibling))
                        continue;

                if (cpu_to_node(sibling) != node) {
                        WARN(1, "CPU thread siblings %d and %d don't belong"
                                " to the same node!\n", cpu, sibling);
                        break;
                }
        }
}

static int cpu_numa_callback(struct notifier_block *nfb, unsigned long action,
                             void *hcpu)
{
        unsigned long lcpu = (unsigned long)hcpu;
        int ret = NOTIFY_DONE, nid;

        switch (action) {
        case CPU_UP_PREPARE:
        case CPU_UP_PREPARE_FROZEN:
                nid = numa_setup_cpu(lcpu);
                verify_cpu_node_mapping((int)lcpu, nid);
                ret = NOTIFY_OK;
                break;
#ifdef CONFIG_HOTPLUG_CPU
        case CPU_DEAD:
        case CPU_DEAD_FROZEN:
        case CPU_UP_CANCELED:
        case CPU_UP_CANCELED_FROZEN:
                unmap_cpu_from_node(lcpu);
                break;
                ret = NOTIFY_OK;
#endif
        }
        return ret;
}

/*
 * Check and possibly modify a memory region to enforce the memory limit.
 *
 * Returns the size the region should have to enforce the memory limit.
 * This will either be the original value of size, a truncated value,
 * or zero. If the returned value of size is 0 the region should be
 * discarded as it lies wholly above the memory limit.
 */
static unsigned long __init numa_enforce_memory_limit(unsigned long start,
                                                      unsigned long size)
{
        /*
         * We use memblock_end_of_DRAM() in here instead of memory_limit because
         * we've already adjusted it for the limit and it takes care of
         * having memory holes below the limit.  Also, in the case of
         * iommu_is_off, memory_limit is not set but is implicitly enforced.
         */

        if (start + size <= memblock_end_of_DRAM())
                return size;

        if (start >= memblock_end_of_DRAM())
                return 0;

        return memblock_end_of_DRAM() - start;
}

/*
 * Reads the counter for a given entry in
 * linux,drconf-usable-memory property
 */
static inline int __init read_usm_ranges(const __be32 **usm)
{
        /*
         * For each lmb in ibm,dynamic-memory a corresponding
         * entry in linux,drconf-usable-memory property contains
         * a counter followed by that many (base, size) duple.
         * read the counter from linux,drconf-usable-memory
         */
        return read_n_cells(n_mem_size_cells, usm);
}

/*
 * Extract NUMA information from the ibm,dynamic-reconfiguration-memory
 * node.  This assumes n_mem_{addr,size}_cells have been set.
 */
static void __init parse_drconf_memory(struct device_node *memory)
{
        const __be32 *uninitialized_var(dm), *usm;
        unsigned int n, rc, ranges, is_kexec_kdump = 0;
        unsigned long lmb_size, base, size, sz;
        int nid;
        struct assoc_arrays aa = { .arrays = NULL };

        n = of_get_drconf_memory(memory, &dm);
        if (!n)
                return;

        lmb_size = of_get_lmb_size(memory);
        if (!lmb_size)
                return;

        rc = of_get_assoc_arrays(memory, &aa);
        if (rc)
                return;

        /* check if this is a kexec/kdump kernel */
        usm = of_get_usable_memory(memory);
        if (usm != NULL)
                is_kexec_kdump = 1;

        for (; n != 0; --n) {
                struct of_drconf_cell drmem;

                read_drconf_cell(&drmem, &dm);

                /* skip this block if the reserved bit is set in flags (0x80)
                   or if the block is not assigned to this partition (0x8) */
                if ((drmem.flags & DRCONF_MEM_RESERVED)
                    || !(drmem.flags & DRCONF_MEM_ASSIGNED))
                        continue;

                base = drmem.base_addr;
                size = lmb_size;
                ranges = 1;

                if (is_kexec_kdump) {
                        ranges = read_usm_ranges(&usm);
                        if (!ranges) /* there are no (base, size) duple */
                                continue;
                }
                do {
                        if (is_kexec_kdump) {
                                base = read_n_cells(n_mem_addr_cells, &usm);
                                size = read_n_cells(n_mem_size_cells, &usm);
                        }
                        nid = of_drconf_to_nid_single(&drmem, &aa);
                        fake_numa_create_new_node(
                                ((base + size) >> PAGE_SHIFT),
                                           &nid);
                        node_set_online(nid);
                        sz = numa_enforce_memory_limit(base, size);
                        if (sz)
                                memblock_set_node(base, sz,
                                                  &memblock.memory, nid);
                } while (--ranges);
        }
}

static int __init parse_numa_properties(void)
{
        struct device_node *memory;
        int default_nid = 0;
        unsigned long i;

        if (numa_enabled == 0) {
                printk(KERN_WARNING "NUMA disabled by user\n");
                return -1;
        }

        min_common_depth = find_min_common_depth();

        if (min_common_depth < 0)
                return min_common_depth;

        dbg("NUMA associativity depth for CPU/Memory: %d\n", min_common_depth);

        /*
         * Even though we connect cpus to numa domains later in SMP
         * init, we need to know the node ids now. This is because
         * each node to be onlined must have NODE_DATA etc backing it.
         */
        for_each_present_cpu(i) {
                struct device_node *cpu;
                int nid;

                cpu = of_get_cpu_node(i, NULL);
                BUG_ON(!cpu);
                nid = of_node_to_nid_single(cpu);
                of_node_put(cpu);

                /*
                 * Don't fall back to default_nid yet -- we will plug
                 * cpus into nodes once the memory scan has discovered
                 * the topology.
                 */
                if (nid < 0)
                        continue;
                node_set_online(nid);
        }

        get_n_mem_cells(&n_mem_addr_cells, &n_mem_size_cells);

        for_each_node_by_type(memory, "memory") {
                unsigned long start;
                unsigned long size;
                int nid;
                int ranges;
                const __be32 *memcell_buf;
                unsigned int len;

                memcell_buf = of_get_property(memory,
                        "linux,usable-memory", &len);
                if (!memcell_buf || len <= 0)
                        memcell_buf = of_get_property(memory, "reg", &len);
                if (!memcell_buf || len <= 0)
                        continue;

                /* ranges in cell */
                ranges = (len >> 2) / (n_mem_addr_cells + n_mem_size_cells);
new_range:
                /* these are order-sensitive, and modify the buffer pointer */
                start = read_n_cells(n_mem_addr_cells, &memcell_buf);
                size = read_n_cells(n_mem_size_cells, &memcell_buf);

                /*
                 * Assumption: either all memory nodes or none will
                 * have associativity properties.  If none, then
                 * everything goes to default_nid.
                 */
                nid = of_node_to_nid_single(memory);
                if (nid < 0)
                        nid = default_nid;

                fake_numa_create_new_node(((start + size) >> PAGE_SHIFT), &nid);
                node_set_online(nid);

                if (!(size = numa_enforce_memory_limit(start, size))) {
                        if (--ranges)
                                goto new_range;
                        else
                                continue;
                }

                memblock_set_node(start, size, &memblock.memory, nid);

                if (--ranges)
                        goto new_range;
        }

        /*
         * Now do the same thing for each MEMBLOCK listed in the
         * ibm,dynamic-memory property in the
         * ibm,dynamic-reconfiguration-memory node.
         */
        memory = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
        if (memory)
                parse_drconf_memory(memory);

        return 0;
}

static void __init setup_nonnuma(void)
{
        unsigned long top_of_ram = memblock_end_of_DRAM();
        unsigned long total_ram = memblock_phys_mem_size();
        unsigned long start_pfn, end_pfn;
        unsigned int nid = 0;
        struct memblock_region *reg;

        printk(KERN_DEBUG "Top of RAM: 0x%lx, Total RAM: 0x%lx\n",
               top_of_ram, total_ram);
        printk(KERN_DEBUG "Memory hole size: %ldMB\n",
               (top_of_ram - total_ram) >> 20);

        for_each_memblock(memory, reg) {
                start_pfn = memblock_region_memory_base_pfn(reg);
                end_pfn = memblock_region_memory_end_pfn(reg);

                fake_numa_create_new_node(end_pfn, &nid);
                memblock_set_node(PFN_PHYS(start_pfn),
                                  PFN_PHYS(end_pfn - start_pfn),
                                  &memblock.memory, nid);
                node_set_online(nid);
        }
}

void __init dump_numa_cpu_topology(void)
{
        unsigned int node;
        unsigned int cpu, count;

        if (min_common_depth == -1 || !numa_enabled)
                return;

        for_each_online_node(node) {
                printk(KERN_DEBUG "Node %d CPUs:", node);

                count = 0;
                /*
                 * If we used a CPU iterator here we would miss printing
                 * the holes in the cpumap.
                 */
                for (cpu = 0; cpu < nr_cpu_ids; cpu++) {
                        if (cpumask_test_cpu(cpu,
                                        node_to_cpumask_map[node])) {
                                if (count == 0)
                                        printk(" %u", cpu);
                                ++count;
                        } else {
                                if (count > 1)
                                        printk("-%u", cpu - 1);
                                count = 0;
                        }
                }

                if (count > 1)
                        printk("-%u", nr_cpu_ids - 1);
                printk("\n");
        }
}

static void __init dump_numa_memory_topology(void)
{
        unsigned int node;
        unsigned int count;

        if (min_common_depth == -1 || !numa_enabled)
                return;

        for_each_online_node(node) {
                unsigned long i;

                printk(KERN_DEBUG "Node %d Memory:", node);

                count = 0;

                for (i = 0; i < memblock_end_of_DRAM();
                     i += (1 << SECTION_SIZE_BITS)) {
                        if (early_pfn_to_nid(i >> PAGE_SHIFT) == node) {
                                if (count == 0)
                                        printk(" 0x%lx", i);
                                ++count;
                        } else {
                                if (count > 0)
                                        printk("-0x%lx", i);
                                count = 0;
                        }
                }

                if (count > 0)
                        printk("-0x%lx", i);
                printk("\n");
        }
}

/*
 * Allocate some memory, satisfying the memblock or bootmem allocator where
 * required. nid is the preferred node and end is the physical address of
 * the highest address in the node.
 *
 * Returns the virtual address of the memory.
 */
static void __init *careful_zallocation(int nid, unsigned long size,
                                       unsigned long align,
                                       unsigned long end_pfn)
{
        void *ret;
        int new_nid;
        unsigned long ret_paddr;

        ret_paddr = __memblock_alloc_base(size, align, end_pfn << PAGE_SHIFT);

        /* retry over all memory */
        if (!ret_paddr)
                ret_paddr = __memblock_alloc_base(size, align, memblock_end_of_DRAM());

        if (!ret_paddr)
                panic("numa.c: cannot allocate %lu bytes for node %d",
                      size, nid);

        ret = __va(ret_paddr);

        /*
         * We initialize the nodes in numeric order: 0, 1, 2...
         * and hand over control from the MEMBLOCK allocator to the
         * bootmem allocator.  If this function is called for
         * node 5, then we know that all nodes <5 are using the
         * bootmem allocator instead of the MEMBLOCK allocator.
         *
         * So, check the nid from which this allocation came
         * and double check to see if we need to use bootmem
         * instead of the MEMBLOCK.  We don't free the MEMBLOCK memory
         * since it would be useless.
         */
        new_nid = early_pfn_to_nid(ret_paddr >> PAGE_SHIFT);
        if (new_nid < nid) {
                ret = __alloc_bootmem_node(NODE_DATA(new_nid),
                                size, align, 0);

                dbg("alloc_bootmem %p %lx\n", ret, size);
        }

        memset(ret, 0, size);
        return ret;
}

static struct notifier_block ppc64_numa_nb = {
        .notifier_call = cpu_numa_callback,
        .priority = 1 /* Must run before sched domains notifier. */
};

static void __init mark_reserved_regions_for_nid(int nid)
{
        struct pglist_data *node = NODE_DATA(nid);
        struct memblock_region *reg;

        for_each_memblock(reserved, reg) {
                unsigned long physbase = reg->base;
                unsigned long size = reg->size;
                unsigned long start_pfn = physbase >> PAGE_SHIFT;
                unsigned long end_pfn = PFN_UP(physbase + size);
                struct node_active_region node_ar;
                unsigned long node_end_pfn = pgdat_end_pfn(node);

                /*
                 * Check to make sure that this memblock.reserved area is
                 * within the bounds of the node that we care about.
                 * Checking the nid of the start and end points is not
                 * sufficient because the reserved area could span the
                 * entire node.
                 */
                if (end_pfn <= node->node_start_pfn ||
                    start_pfn >= node_end_pfn)
                        continue;

                get_node_active_region(start_pfn, &node_ar);
                while (start_pfn < end_pfn &&
                        node_ar.start_pfn < node_ar.end_pfn) {
                        unsigned long reserve_size = size;
                        /*
                         * if reserved region extends past active region
                         * then trim size to active region
                         */
                        if (end_pfn > node_ar.end_pfn)
                                reserve_size = (node_ar.end_pfn << PAGE_SHIFT)
                                        - physbase;
                        /*
                         * Only worry about *this* node, others may not
                         * yet have valid NODE_DATA().
                         */
                        if (node_ar.nid == nid) {
                                dbg("reserve_bootmem %lx %lx nid=%d\n",
                                        physbase, reserve_size, node_ar.nid);
                                reserve_bootmem_node(NODE_DATA(node_ar.nid),
                                                physbase, reserve_size,
                                                BOOTMEM_DEFAULT);
                        }
                        /*
                         * if reserved region is contained in the active region
                         * then done.
                         */
                        if (end_pfn <= node_ar.end_pfn)
                                break;

                        /*
                         * reserved region extends past the active region
                         *   get next active region that contains this
                         *   reserved region
                         */
                        start_pfn = node_ar.end_pfn;
                        physbase = start_pfn << PAGE_SHIFT;
                        size = size - reserve_size;
                        get_node_active_region(start_pfn, &node_ar);
                }
        }
}


void __init do_init_bootmem(void)
{
        int nid;

        min_low_pfn = 0;
        max_low_pfn = memblock_end_of_DRAM() >> PAGE_SHIFT;
        max_pfn = max_low_pfn;

        if (parse_numa_properties())
                setup_nonnuma();
        else
                dump_numa_memory_topology();

        for_each_online_node(nid) {
                unsigned long start_pfn, end_pfn;
                void *bootmem_vaddr;
                unsigned long bootmap_pages;

                get_pfn_range_for_nid(nid, &start_pfn, &end_pfn);

                /*
                 * Allocate the node structure node local if possible
                 *
                 * Be careful moving this around, as it relies on all
                 * previous nodes' bootmem to be initialized and have
                 * all reserved areas marked.
                 */
                NODE_DATA(nid) = careful_zallocation(nid,
                                        sizeof(struct pglist_data),
                                        SMP_CACHE_BYTES, end_pfn);

                dbg("node %d\n", nid);
                dbg("NODE_DATA() = %p\n", NODE_DATA(nid));

                NODE_DATA(nid)->bdata = &bootmem_node_data[nid];
                NODE_DATA(nid)->node_start_pfn = start_pfn;
                NODE_DATA(nid)->node_spanned_pages = end_pfn - start_pfn;

                if (NODE_DATA(nid)->node_spanned_pages == 0)
                        continue;

                dbg("start_paddr = %lx\n", start_pfn << PAGE_SHIFT);
                dbg("end_paddr = %lx\n", end_pfn << PAGE_SHIFT);

                bootmap_pages = bootmem_bootmap_pages(end_pfn - start_pfn);
                bootmem_vaddr = careful_zallocation(nid,
                                        bootmap_pages << PAGE_SHIFT,
                                        PAGE_SIZE, end_pfn);

                dbg("bootmap_vaddr = %p\n", bootmem_vaddr);

                init_bootmem_node(NODE_DATA(nid),
                                  __pa(bootmem_vaddr) >> PAGE_SHIFT,
                                  start_pfn, end_pfn);

                free_bootmem_with_active_regions(nid, end_pfn);
                /*
                 * Be very careful about moving this around.  Future
                 * calls to careful_zallocation() depend on this getting
                 * done correctly.
                 */
                mark_reserved_regions_for_nid(nid);
                sparse_memory_present_with_active_regions(nid);
        }

        init_bootmem_done = 1;

        /*
         * Now bootmem is initialised we can create the node to cpumask
         * lookup tables and setup the cpu callback to populate them.
         */
        setup_node_to_cpumask_map();

        reset_numa_cpu_lookup_table();
        register_cpu_notifier(&ppc64_numa_nb);
        cpu_numa_callback(&ppc64_numa_nb, CPU_UP_PREPARE,
                          (void *)(unsigned long)boot_cpuid);
}

void __init paging_init(void)
{
        unsigned long max_zone_pfns[MAX_NR_ZONES];
        memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
        max_zone_pfns[ZONE_DMA] = memblock_end_of_DRAM() >> PAGE_SHIFT;
        free_area_init_nodes(max_zone_pfns);
}

static int __init early_numa(char *p)
{
        if (!p)
                return 0;

        if (strstr(p, "off"))
                numa_enabled = 0;

        if (strstr(p, "debug"))
                numa_debug = 1;

        p = strstr(p, "fake=");
        if (p)
                cmdline = p + strlen("fake=");

        return 0;
}
early_param("numa", early_numa);

#ifdef CONFIG_MEMORY_HOTPLUG
/*
 * Find the node associated with a hot added memory section for
 * memory represented in the device tree by the property
 * ibm,dynamic-reconfiguration-memory/ibm,dynamic-memory.
 */
static int hot_add_drconf_scn_to_nid(struct device_node *memory,
                                     unsigned long scn_addr)
{
        const __be32 *dm;
        unsigned int drconf_cell_cnt, rc;
        unsigned long lmb_size;
        struct assoc_arrays aa;
        int nid = -1;

        drconf_cell_cnt = of_get_drconf_memory(memory, &dm);
        if (!drconf_cell_cnt)
                return -1;

        lmb_size = of_get_lmb_size(memory);
        if (!lmb_size)
                return -1;

        rc = of_get_assoc_arrays(memory, &aa);
        if (rc)
                return -1;

        for (; drconf_cell_cnt != 0; --drconf_cell_cnt) {
                struct of_drconf_cell drmem;

                read_drconf_cell(&drmem, &dm);

                /* skip this block if it is reserved or not assigned to
                 * this partition */
                if ((drmem.flags & DRCONF_MEM_RESERVED)
                    || !(drmem.flags & DRCONF_MEM_ASSIGNED))
                        continue;

                if ((scn_addr < drmem.base_addr)
                    || (scn_addr >= (drmem.base_addr + lmb_size)))
                        continue;

                nid = of_drconf_to_nid_single(&drmem, &aa);
                break;
        }

        return nid;
}

/*
 * Find the node associated with a hot added memory section for memory
 * represented in the device tree as a node (i.e. memory@XXXX) for
 * each memblock.
 */
static int hot_add_node_scn_to_nid(unsigned long scn_addr)
{
        struct device_node *memory;
        int nid = -1;

        for_each_node_by_type(memory, "memory") {
                unsigned long start, size;
                int ranges;
                const __be32 *memcell_buf;
                unsigned int len;

                memcell_buf = of_get_property(memory, "reg", &len);
                if (!memcell_buf || len <= 0)
                        continue;

                /* ranges in cell */
                ranges = (len >> 2) / (n_mem_addr_cells + n_mem_size_cells);

                while (ranges--) {
                        start = read_n_cells(n_mem_addr_cells, &memcell_buf);
                        size = read_n_cells(n_mem_size_cells, &memcell_buf);

                        if ((scn_addr < start) || (scn_addr >= (start + size)))
                                continue;

                        nid = of_node_to_nid_single(memory);
                        break;
                }

                if (nid >= 0)
                        break;
        }

        of_node_put(memory);

        return nid;
}

/*
 * Find the node associated with a hot added memory section.  Section
 * corresponds to a SPARSEMEM section, not an MEMBLOCK.  It is assumed that
 * sections are fully contained within a single MEMBLOCK.
 */
int hot_add_scn_to_nid(unsigned long scn_addr)
{
        struct device_node *memory = NULL;
        int nid, found = 0;

        if (!numa_enabled || (min_common_depth < 0))
                return first_online_node;

        memory = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
        if (memory) {
                nid = hot_add_drconf_scn_to_nid(memory, scn_addr);
                of_node_put(memory);
        } else {
                nid = hot_add_node_scn_to_nid(scn_addr);
        }

        if (nid < 0 || !node_online(nid))
                nid = first_online_node;

        if (NODE_DATA(nid)->node_spanned_pages)
                return nid;

        for_each_online_node(nid) {
                if (NODE_DATA(nid)->node_spanned_pages) {
                        found = 1;
                        break;
                }
        }

        BUG_ON(!found);
        return nid;
}

static u64 hot_add_drconf_memory_max(void)
{
        struct device_node *memory = NULL;
        unsigned int drconf_cell_cnt = 0;
        u64 lmb_size = 0;
        const __be32 *dm = NULL;

        memory = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
        if (memory) {
                drconf_cell_cnt = of_get_drconf_memory(memory, &dm);
                lmb_size = of_get_lmb_size(memory);
                of_node_put(memory);
        }
        return lmb_size * drconf_cell_cnt;
}

/*
 * memory_hotplug_max - return max address of memory that may be added
 *
 * This is currently only used on systems that support drconfig memory
 * hotplug.
 */
u64 memory_hotplug_max(void)
{
        return max(hot_add_drconf_memory_max(), memblock_end_of_DRAM());
}
#endif /* CONFIG_MEMORY_HOTPLUG */

/* Virtual Processor Home Node (VPHN) support */
#ifdef CONFIG_PPC_SPLPAR
struct topology_update_data {
        struct topology_update_data *next;
        unsigned int cpu;
        int old_nid;
        int new_nid;
};

static u8 vphn_cpu_change_counts[NR_CPUS][MAX_DISTANCE_REF_POINTS];
static cpumask_t cpu_associativity_changes_mask;
static int vphn_enabled;
static int prrn_enabled;
static void reset_topology_timer(void);

/*
 * Store the current values of the associativity change counters in the
 * hypervisor.
 */
static void setup_cpu_associativity_change_counters(void)
{
        int cpu;

        /* The VPHN feature supports a maximum of 8 reference points */
        BUILD_BUG_ON(MAX_DISTANCE_REF_POINTS > 8);

        for_each_possible_cpu(cpu) {
                int i;
                u8 *counts = vphn_cpu_change_counts[cpu];
                volatile u8 *hypervisor_counts = lppaca[cpu].vphn_assoc_counts;

                for (i = 0; i < distance_ref_points_depth; i++)
                        counts[i] = hypervisor_counts[i];
        }
}

/*
 * The hypervisor maintains a set of 8 associativity change counters in
 * the VPA of each cpu that correspond to the associativity levels in the
 * ibm,associativity-reference-points property. When an associativity
 * level changes, the corresponding counter is incremented.
 *
 * Set a bit in cpu_associativity_changes_mask for each cpu whose home
 * node associativity levels have changed.
 *
 * Returns the number of cpus with unhandled associativity changes.
 */
static int update_cpu_associativity_changes_mask(void)
{
        int cpu;
        cpumask_t *changes = &cpu_associativity_changes_mask;

        for_each_possible_cpu(cpu) {
                int i, changed = 0;
                u8 *counts = vphn_cpu_change_counts[cpu];
                volatile u8 *hypervisor_counts = lppaca[cpu].vphn_assoc_counts;

                for (i = 0; i < distance_ref_points_depth; i++) {
                        if (hypervisor_counts[i] != counts[i]) {
                                counts[i] = hypervisor_counts[i];
                                changed = 1;
                        }
                }
                if (changed) {
                        cpumask_or(changes, changes, cpu_sibling_mask(cpu));
                        cpu = cpu_last_thread_sibling(cpu);
                }
        }

        return cpumask_weight(changes);
}

/*
 * 6 64-bit registers unpacked into 12 32-bit associativity values. To form
 * the complete property we have to add the length in the first cell.
 */
#define VPHN_ASSOC_BUFSIZE (6*sizeof(u64)/sizeof(u32) + 1)

/*
 * Convert the associativity domain numbers returned from the hypervisor
 * to the sequence they would appear in the ibm,associativity property.
 */
static int vphn_unpack_associativity(const long *packed, __be32 *unpacked)
{
        int i, nr_assoc_doms = 0;
        const __be16 *field = (const __be16 *) packed;

#define VPHN_FIELD_UNUSED       (0xffff)
#define VPHN_FIELD_MSB          (0x8000)
#define VPHN_FIELD_MASK         (~VPHN_FIELD_MSB)

        for (i = 1; i < VPHN_ASSOC_BUFSIZE; i++) {
                if (be16_to_cpup(field) == VPHN_FIELD_UNUSED) {
                        /* All significant fields processed, and remaining
                         * fields contain the reserved value of all 1's.
                         * Just store them.
                         */
                        unpacked[i] = *((__be32 *)field);
                        field += 2;
                } else if (be16_to_cpup(field) & VPHN_FIELD_MSB) {
                        /* Data is in the lower 15 bits of this field */
                        unpacked[i] = cpu_to_be32(
                                be16_to_cpup(field) & VPHN_FIELD_MASK);
                        field++;
                        nr_assoc_doms++;
                } else {
                        /* Data is in the lower 15 bits of this field
                         * concatenated with the next 16 bit field
                         */
                        unpacked[i] = *((__be32 *)field);
                        field += 2;
                        nr_assoc_doms++;
                }
        }

        /* The first cell contains the length of the property */
        unpacked[0] = cpu_to_be32(nr_assoc_doms);

        return nr_assoc_doms;
}

/*
 * Retrieve the new associativity information for a virtual processor's
 * home node.
 */
static long hcall_vphn(unsigned long cpu, __be32 *associativity)
{
        long rc;
        long retbuf[PLPAR_HCALL9_BUFSIZE] = {0};
        u64 flags = 1;
        int hwcpu = get_hard_smp_processor_id(cpu);

        rc = plpar_hcall9(H_HOME_NODE_ASSOCIATIVITY, retbuf, flags, hwcpu);
        vphn_unpack_associativity(retbuf, associativity);

        return rc;
}

static long vphn_get_associativity(unsigned long cpu,
                                        __be32 *associativity)
{
        long rc;

        rc = hcall_vphn(cpu, associativity);

        switch (rc) {
        case H_FUNCTION:
                printk(KERN_INFO
                        "VPHN is not supported. Disabling polling...\n");
                stop_topology_update();
                break;
        case H_HARDWARE:
                printk(KERN_ERR
                        "hcall_vphn() experienced a hardware fault "
                        "preventing VPHN. Disabling polling...\n");
                stop_topology_update();
        }

        return rc;
}

/*
 * Update the CPU maps and sysfs entries for a single CPU when its NUMA
 * characteristics change. This function doesn't perform any locking and is
 * only safe to call from stop_machine().
 */
static int update_cpu_topology(void *data)
{
        struct topology_update_data *update;
        unsigned long cpu;

        if (!data)
                return -EINVAL;

        cpu = smp_processor_id();

        for (update = data; update; update = update->next) {
                if (cpu != update->cpu)
                        continue;

                unmap_cpu_from_node(update->cpu);
                map_cpu_to_node(update->cpu, update->new_nid);
                vdso_getcpu_init();
        }

        return 0;
}

static int update_lookup_table(void *data)
{
        struct topology_update_data *update;

        if (!data)
                return -EINVAL;

        /*
         * Upon topology update, the numa-cpu lookup table needs to be updated
         * for all threads in the core, including offline CPUs, to ensure that
         * future hotplug operations respect the cpu-to-node associativity
         * properly.
         */
        for (update = data; update; update = update->next) {
                int nid, base, j;

                nid = update->new_nid;
                base = cpu_first_thread_sibling(update->cpu);

                for (j = 0; j < threads_per_core; j++) {
                        update_numa_cpu_lookup_table(base + j, nid);
                }
        }

        return 0;
}

/*
 * Update the node maps and sysfs entries for each cpu whose home node
 * has changed. Returns 1 when the topology has changed, and 0 otherwise.
 */
int arch_update_cpu_topology(void)
{
        unsigned int cpu, sibling, changed = 0;
        struct topology_update_data *updates, *ud;
        __be32 associativity[VPHN_ASSOC_BUFSIZE] = {0};
        cpumask_t updated_cpus;
        struct device *dev;
        int weight, new_nid, i = 0;

        weight = cpumask_weight(&cpu_associativity_changes_mask);
        if (!weight)
                return 0;

        updates = kzalloc(weight * (sizeof(*updates)), GFP_KERNEL);
        if (!updates)
                return 0;

        cpumask_clear(&updated_cpus);

        for_each_cpu(cpu, &cpu_associativity_changes_mask) {
                /*
                 * If siblings aren't flagged for changes, updates list
                 * will be too short. Skip on this update and set for next
                 * update.
                 */
                if (!cpumask_subset(cpu_sibling_mask(cpu),
                                        &cpu_associativity_changes_mask)) {
                        pr_info("Sibling bits not set for associativity "
                                        "change, cpu%d\n", cpu);
                        cpumask_or(&cpu_associativity_changes_mask,
                                        &cpu_associativity_changes_mask,
                                        cpu_sibling_mask(cpu));
                        cpu = cpu_last_thread_sibling(cpu);
                        continue;
                }

                /* Use associativity from first thread for all siblings */
                vphn_get_associativity(cpu, associativity);
                new_nid = associativity_to_nid(associativity);
                if (new_nid < 0 || !node_online(new_nid))
                        new_nid = first_online_node;

                if (new_nid == numa_cpu_lookup_table[cpu]) {
                        cpumask_andnot(&cpu_associativity_changes_mask,
                                        &cpu_associativity_changes_mask,
                                        cpu_sibling_mask(cpu));
                        cpu = cpu_last_thread_sibling(cpu);
                        continue;
                }

                for_each_cpu(sibling, cpu_sibling_mask(cpu)) {
                        ud = &updates[i++];
                        ud->cpu = sibling;
                        ud->new_nid = new_nid;
                        ud->old_nid = numa_cpu_lookup_table[sibling];
                        cpumask_set_cpu(sibling, &updated_cpus);
                        if (i < weight)
                                ud->next = &updates[i];
                }
                cpu = cpu_last_thread_sibling(cpu);
        }

        stop_machine(update_cpu_topology, &updates[0], &updated_cpus);

        /*
         * Update the numa-cpu lookup table with the new mappings, even for
         * offline CPUs. It is best to perform this update from the stop-
         * machine context.
         */
        stop_machine(update_lookup_table, &updates[0],
                                        cpumask_of(raw_smp_processor_id()));

        for (ud = &updates[0]; ud; ud = ud->next) {
                unregister_cpu_under_node(ud->cpu, ud->old_nid);
                register_cpu_under_node(ud->cpu, ud->new_nid);

                dev = get_cpu_device(ud->cpu);
                if (dev)
                        kobject_uevent(&dev->kobj, KOBJ_CHANGE);
                cpumask_clear_cpu(ud->cpu, &cpu_associativity_changes_mask);
                changed = 1;
        }

        kfree(updates);
        return changed;
}

static void topology_work_fn(struct work_struct *work)
{
        rebuild_sched_domains();
}
static DECLARE_WORK(topology_work, topology_work_fn);

static void topology_schedule_update(void)
{
        schedule_work(&topology_work);
}

static void topology_timer_fn(unsigned long ignored)
{
        if (prrn_enabled && cpumask_weight(&cpu_associativity_changes_mask))
                topology_schedule_update();
        else if (vphn_enabled) {
                if (update_cpu_associativity_changes_mask() > 0)
                        topology_schedule_update();
                reset_topology_timer();
        }
}
static struct timer_list topology_timer =
        TIMER_INITIALIZER(topology_timer_fn, 0, 0);

static void reset_topology_timer(void)
{
        topology_timer.data = 0;
        topology_timer.expires = jiffies + 60 * HZ;
        mod_timer(&topology_timer, topology_timer.expires);
}

#ifdef CONFIG_SMP

static void stage_topology_update(int core_id)
{
        cpumask_or(&cpu_associativity_changes_mask,
                &cpu_associativity_changes_mask, cpu_sibling_mask(core_id));
        reset_topology_timer();
}

static int dt_update_callback(struct notifier_block *nb,
                                unsigned long action, void *data)
{
        struct of_prop_reconfig *update;
        int rc = NOTIFY_DONE;

        switch (action) {
        case OF_RECONFIG_UPDATE_PROPERTY:
                update = (struct of_prop_reconfig *)data;
                if (!of_prop_cmp(update->dn->type, "cpu") &&
                    !of_prop_cmp(update->prop->name, "ibm,associativity")) {
                        u32 core_id;
                        of_property_read_u32(update->dn, "reg", &core_id);
                        stage_topology_update(core_id);
                        rc = NOTIFY_OK;
                }
                break;
        }

        return rc;
}

static struct notifier_block dt_update_nb = {
        .notifier_call = dt_update_callback,
};

#endif

/*
 * Start polling for associativity changes.
 */
int start_topology_update(void)
{
        int rc = 0;

        if (firmware_has_feature(FW_FEATURE_PRRN)) {
                if (!prrn_enabled) {
                        prrn_enabled = 1;
                        vphn_enabled = 0;
#ifdef CONFIG_SMP
                        rc = of_reconfig_notifier_register(&dt_update_nb);
#endif
                }
        } else if (firmware_has_feature(FW_FEATURE_VPHN) &&
                   lppaca_shared_proc(get_lppaca())) {
                if (!vphn_enabled) {
                        prrn_enabled = 0;
                        vphn_enabled = 1;
                        setup_cpu_associativity_change_counters();
                        init_timer_deferrable(&topology_timer);
                        reset_topology_timer();
                }
        }

        return rc;
}

/*
 * Disable polling for VPHN associativity changes.
 */
int stop_topology_update(void)
{
        int rc = 0;

        if (prrn_enabled) {
                prrn_enabled = 0;
#ifdef CONFIG_SMP
                rc = of_reconfig_notifier_unregister(&dt_update_nb);
#endif
        } else if (vphn_enabled) {
                vphn_enabled = 0;
                rc = del_timer_sync(&topology_timer);
        }

        return rc;
}

int prrn_is_enabled(void)
{
        return prrn_enabled;
}

static int topology_read(struct seq_file *file, void *v)
{
        if (vphn_enabled || prrn_enabled)
                seq_puts(file, "on\n");
        else
                seq_puts(file, "off\n");

        return 0;
}

static int topology_open(struct inode *inode, struct file *file)
{
        return single_open(file, topology_read, NULL);
}

static ssize_t topology_write(struct file *file, const char __user *buf,
                              size_t count, loff_t *off)
{
        char kbuf[4]; /* "on" or "off" plus null. */
        int read_len;

        read_len = count < 3 ? count : 3;
        if (copy_from_user(kbuf, buf, read_len))
                return -EINVAL;

        kbuf[read_len] = '\0';

        if (!strncmp(kbuf, "on", 2))
                start_topology_update();
        else if (!strncmp(kbuf, "off", 3))
                stop_topology_update();
        else
                return -EINVAL;

        return count;
}

static const struct file_operations topology_ops = {
        .read = seq_read,
        .write = topology_write,
        .open = topology_open,
        .release = single_release
};

static int topology_update_init(void)
{
        start_topology_update();
        proc_create("powerpc/topology_updates", 0644, NULL, &topology_ops);

        return 0;
}
device_initcall(topology_update_init);
#endif /* CONFIG_PPC_SPLPAR */