hotplug-memory.c

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/*
 * pseries Memory Hotplug infrastructure.
 *
 * Copyright (C) 2008 Badari Pulavarty, IBM Corporation
 *
 *      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/of.h>
#include <linux/memblock.h>
#include <linux/vmalloc.h>
#include <linux/memory.h>

#include <asm/firmware.h>
#include <asm/machdep.h>
#include <asm/pSeries_reconfig.h>
#include <asm/sparsemem.h>

static unsigned long get_memblock_size(void)
{
    struct device_node *np;
    unsigned int memblock_size = MIN_MEMORY_BLOCK_SIZE;
    struct resource r;

    np = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
    if (np) {
        const __be64 *size;

        size = of_get_property(np, "ibm,lmb-size", NULL);
        if (size)
            memblock_size = be64_to_cpup(size);
        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;
}

/* WARNING: This is going to override the generic definition whenever
 * pseries is built-in regardless of what platform is active at boot
 * time. This is fine for now as this is the only "option" and it
 * should work everywhere. If not, we'll have to turn this into a
 * ppc_md. callback
 */
unsigned long memory_block_size_bytes(void)
{
    return get_memblock_size();
}

static int pseries_remove_memblock(unsigned long base, unsigned int memblock_size)
{
    unsigned long start, start_pfn;
    struct zone *zone;
    int ret;
    unsigned long section;
    unsigned long sections_to_remove;

    start_pfn = base >> PAGE_SHIFT;

    if (!pfn_valid(start_pfn)) {
        memblock_remove(base, memblock_size);
        return 0;
    }

    zone = page_zone(pfn_to_page(start_pfn));

    /*
     * Remove section mappings and sysfs entries for the
     * section of the memory we are removing.
     *
     * NOTE: Ideally, this should be done in generic code like
     * remove_memory(). But remove_memory() gets called by writing
     * to sysfs "state" file and we can't remove sysfs entries
     * while writing to it. So we have to defer it to here.
     */
    sections_to_remove = (memblock_size >> PAGE_SHIFT) / PAGES_PER_SECTION;
    for (section = 0; section < sections_to_remove; section++) {
        unsigned long pfn = start_pfn + section * PAGES_PER_SECTION;
        ret = __remove_pages(zone, pfn, PAGES_PER_SECTION);
        if (ret)
            return ret;
    }

    /*
     * Update memory regions for memory remove
     */
    memblock_remove(base, memblock_size);

    /*
     * Remove htab bolted mappings for this section of memory
     */
    start = (unsigned long)__va(base);
    ret = remove_section_mapping(start, start + memblock_size);

    /* Ensure all vmalloc mappings are flushed in case they also
     * hit that section of memory
     */
    vm_unmap_aliases();

    return ret;
}

static int pseries_remove_memory(struct device_node *np)
{
    const char *type;
    const unsigned int *regs;
    unsigned long base;
    unsigned int lmb_size;
    int ret = -EINVAL;

    /*
     * Check to see if we are actually removing memory
     */
    type = of_get_property(np, "device_type", NULL);
    if (type == NULL || strcmp(type, "memory") != 0)
        return 0;

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

    base = *(unsigned long *)regs;
    lmb_size = regs[3];

    ret = pseries_remove_memblock(base, lmb_size);
    return ret;
}

static int pseries_add_memory(struct device_node *np)
{
    const char *type;
    const unsigned int *regs;
    unsigned long base;
    unsigned int lmb_size;
    int ret = -EINVAL;

    /*
     * Check to see if we are actually adding memory
     */
    type = of_get_property(np, "device_type", NULL);
    if (type == NULL || strcmp(type, "memory") != 0)
        return 0;

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

    base = *(unsigned long *)regs;
    lmb_size = regs[3];

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

static int pseries_drconf_memory(unsigned long *base, unsigned int action)
{
    unsigned long memblock_size;
    int rc;

    memblock_size = get_memblock_size();
    if (!memblock_size)
        return -EINVAL;

    if (action == PSERIES_DRCONF_MEM_ADD) {
        rc = memblock_add(*base, memblock_size);
        rc = (rc < 0) ? -EINVAL : 0;
    } else if (action == PSERIES_DRCONF_MEM_REMOVE) {
        rc = pseries_remove_memblock(*base, memblock_size);
    } else {
        rc = -EINVAL;
    }

    return rc;
}

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

    switch (action) {
    case PSERIES_RECONFIG_ADD:
        err = pseries_add_memory(node);
        break;
    case PSERIES_RECONFIG_REMOVE:
        err = pseries_remove_memory(node);
        break;
    case PSERIES_DRCONF_MEM_ADD:
    case PSERIES_DRCONF_MEM_REMOVE:
        err = pseries_drconf_memory(node, action);
        break;
    }
    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))
        pSeries_reconfig_notifier_register(&pseries_mem_nb);

    return 0;
}
machine_device_initcall(pseries, pseries_memory_hotplug_init);