/*
 * 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/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();
}

#ifdef CONFIG_MEMORY_HOTREMOVE
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;
}
#else
static inline int pseries_remove_memblock(unsigned long base,
                                          unsigned int memblock_size)
{
        return -EOPNOTSUPP;
}
static inline int pseries_remove_memory(struct device_node *np)
{
        return -EOPNOTSUPP;
}
#endif /* CONFIG_MEMORY_HOTREMOVE */

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_update_drconf_memory(struct of_prop_reconfig *pr)
{
        struct of_drconf_cell *new_drmem, *old_drmem;
        unsigned long memblock_size;
        u32 entries;
        u32 *p;
        int i, rc = -EINVAL;

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

        p = (u32 *)of_get_property(pr->dn, "ibm,dynamic-memory", NULL);
        if (!p)
                return -EINVAL;

        /* The first int of the property is the number of lmb's described
         * by the property. This is followed by an array of of_drconf_cell
         * entries. Get the niumber of entries and skip to the array of
         * of_drconf_cell's.
         */
        entries = *p++;
        old_drmem = (struct of_drconf_cell *)p;

        p = (u32 *)pr->prop->value;
        p++;
        new_drmem = (struct of_drconf_cell *)p;

        for (i = 0; i < entries; i++) {
                if ((old_drmem[i].flags & DRCONF_MEM_ASSIGNED) &&
                    (!(new_drmem[i].flags & DRCONF_MEM_ASSIGNED))) {
                        rc = pseries_remove_memblock(old_drmem[i].base_addr,
                                                     memblock_size);
                        break;
                } else if ((!(old_drmem[i].flags & DRCONF_MEM_ASSIGNED)) &&
                           (new_drmem[i].flags & DRCONF_MEM_ASSIGNED)) {
                        rc = memblock_add(old_drmem[i].base_addr,
                                          memblock_size);
                        rc = (rc < 0) ? -EINVAL : 0;
                        break;
                }
        }

        return rc;
}

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

        switch (action) {
        case OF_RECONFIG_ATTACH_NODE:
                err = pseries_add_memory(node);
                break;
        case OF_RECONFIG_DETACH_NODE:
                err = pseries_remove_memory(node);
                break;
        case OF_RECONFIG_UPDATE_PROPERTY:
                pr = (struct of_prop_reconfig *)node;
                if (!strcmp(pr->prop->name, "ibm,dynamic-memory"))
                        err = pseries_update_drconf_memory(pr);
                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))
                of_reconfig_notifier_register(&pseries_mem_nb);

        return 0;
}
machine_device_initcall(pseries, pseries_memory_hotplug_init);