/*
 * drivers/base/memory.c - basic Memory class support
 *
 * Written by Matt Tolentino <matthew.e.tolentino@intel.com>
 *            Dave Hansen <haveblue@us.ibm.com>
 *
 * This file provides the necessary infrastructure to represent
 * a SPARSEMEM-memory-model system's physical memory in /sysfs.
 * All arch-independent code that assumes MEMORY_HOTPLUG requires
 * SPARSEMEM should be contained here, or in mm/memory_hotplug.c.
 */

#include <linux/sysdev.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/topology.h>
#include <linux/capability.h>
#include <linux/device.h>
#include <linux/memory.h>
#include <linux/kobject.h>
#include <linux/memory_hotplug.h>
#include <linux/mm.h>
#include <linux/mutex.h>
#include <linux/stat.h>

#include <asm/atomic.h>
#include <asm/uaccess.h>

#define MEMORY_CLASS_NAME       "memory"

static struct sysdev_class memory_sysdev_class = {
        .name = MEMORY_CLASS_NAME,
};

static const char *memory_uevent_name(struct kset *kset, struct kobject *kobj)
{
        return MEMORY_CLASS_NAME;
}

static int memory_uevent(struct kset *kset, struct kobject *obj, struct kobj_uevent_env *env)
{
        int retval = 0;

        return retval;
}

static struct kset_uevent_ops memory_uevent_ops = {
        .name           = memory_uevent_name,
        .uevent         = memory_uevent,
};

static BLOCKING_NOTIFIER_HEAD(memory_chain);

int register_memory_notifier(struct notifier_block *nb)
{
        return blocking_notifier_chain_register(&memory_chain, nb);
}
EXPORT_SYMBOL(register_memory_notifier);

void unregister_memory_notifier(struct notifier_block *nb)
{
        blocking_notifier_chain_unregister(&memory_chain, nb);
}
EXPORT_SYMBOL(unregister_memory_notifier);

/*
 * register_memory - Setup a sysfs device for a memory block
 */
static
int register_memory(struct memory_block *memory, struct mem_section *section)
{
        int error;

        memory->sysdev.cls = &memory_sysdev_class;
        memory->sysdev.id = __section_nr(section);

        error = sysdev_register(&memory->sysdev);
        return error;
}

static void
unregister_memory(struct memory_block *memory, struct mem_section *section)
{
        BUG_ON(memory->sysdev.cls != &memory_sysdev_class);
        BUG_ON(memory->sysdev.id != __section_nr(section));

        /* drop the ref. we got in remove_memory_block() */
        kobject_put(&memory->sysdev.kobj);
        sysdev_unregister(&memory->sysdev);
}

/*
 * use this as the physical section index that this memsection
 * uses.
 */

static ssize_t show_mem_phys_index(struct sys_device *dev,
                        struct sysdev_attribute *attr, char *buf)
{
        struct memory_block *mem =
                container_of(dev, struct memory_block, sysdev);
        return sprintf(buf, "%08lx\n", mem->phys_index);
}

/*
 * Show whether the section of memory is likely to be hot-removable
 */
static ssize_t show_mem_removable(struct sys_device *dev,
                        struct sysdev_attribute *attr, char *buf)
{
        unsigned long start_pfn;
        int ret;
        struct memory_block *mem =
                container_of(dev, struct memory_block, sysdev);

        start_pfn = section_nr_to_pfn(mem->phys_index);
        ret = is_mem_section_removable(start_pfn, PAGES_PER_SECTION);
        return sprintf(buf, "%d\n", ret);
}

/*
 * online, offline, going offline, etc.
 */
static ssize_t show_mem_state(struct sys_device *dev,
                        struct sysdev_attribute *attr, char *buf)
{
        struct memory_block *mem =
                container_of(dev, struct memory_block, sysdev);
        ssize_t len = 0;

        /*
         * We can probably put these states in a nice little array
         * so that they're not open-coded
         */
        switch (mem->state) {
                case MEM_ONLINE:
                        len = sprintf(buf, "online\n");
                        break;
                case MEM_OFFLINE:
                        len = sprintf(buf, "offline\n");
                        break;
                case MEM_GOING_OFFLINE:
                        len = sprintf(buf, "going-offline\n");
                        break;
                default:
                        len = sprintf(buf, "ERROR-UNKNOWN-%ld\n",
                                        mem->state);
                        WARN_ON(1);
                        break;
        }

        return len;
}

int memory_notify(unsigned long val, void *v)
{
        return blocking_notifier_call_chain(&memory_chain, val, v);
}

/*
 * MEMORY_HOTPLUG depends on SPARSEMEM in mm/Kconfig, so it is
 * OK to have direct references to sparsemem variables in here.
 */
static int
memory_block_action(struct memory_block *mem, unsigned long action)
{
        int i;
        unsigned long psection;
        unsigned long start_pfn, start_paddr;
        struct page *first_page;
        int ret;
        int old_state = mem->state;

        psection = mem->phys_index;
        first_page = pfn_to_page(psection << PFN_SECTION_SHIFT);

        /*
         * The probe routines leave the pages reserved, just
         * as the bootmem code does.  Make sure they're still
         * that way.
         */
        if (action == MEM_ONLINE) {
                for (i = 0; i < PAGES_PER_SECTION; i++) {
                        if (PageReserved(first_page+i))
                                continue;

                        printk(KERN_WARNING "section number %ld page number %d "
                                "not reserved, was it already online? \n",
                                psection, i);
                        return -EBUSY;
                }
        }

        switch (action) {
                case MEM_ONLINE:
                        start_pfn = page_to_pfn(first_page);
                        ret = online_pages(start_pfn, PAGES_PER_SECTION);
                        break;
                case MEM_OFFLINE:
                        mem->state = MEM_GOING_OFFLINE;
                        start_paddr = page_to_pfn(first_page) << PAGE_SHIFT;
                        ret = remove_memory(start_paddr,
                                            PAGES_PER_SECTION << PAGE_SHIFT);
                        if (ret) {
                                mem->state = old_state;
                                break;
                        }
                        break;
                default:
                        WARN(1, KERN_WARNING "%s(%p, %ld) unknown action: %ld\n",
                                        __func__, mem, action, action);
                        ret = -EINVAL;
        }

        return ret;
}

static int memory_block_change_state(struct memory_block *mem,
                unsigned long to_state, unsigned long from_state_req)
{
        int ret = 0;
        mutex_lock(&mem->state_mutex);

        if (mem->state != from_state_req) {
                ret = -EINVAL;
                goto out;
        }

        ret = memory_block_action(mem, to_state);
        if (!ret)
                mem->state = to_state;

out:
        mutex_unlock(&mem->state_mutex);
        return ret;
}

static ssize_t
store_mem_state(struct sys_device *dev,
                struct sysdev_attribute *attr, const char *buf, size_t count)
{
        struct memory_block *mem;
        unsigned int phys_section_nr;
        int ret = -EINVAL;

        mem = container_of(dev, struct memory_block, sysdev);
        phys_section_nr = mem->phys_index;

        if (!present_section_nr(phys_section_nr))
                goto out;

        if (!strncmp(buf, "online", min((int)count, 6)))
                ret = memory_block_change_state(mem, MEM_ONLINE, MEM_OFFLINE);
        else if(!strncmp(buf, "offline", min((int)count, 7)))
                ret = memory_block_change_state(mem, MEM_OFFLINE, MEM_ONLINE);
out:
        if (ret)
                return ret;
        return count;
}

/*
 * phys_device is a bad name for this.  What I really want
 * is a way to differentiate between memory ranges that
 * are part of physical devices that constitute
 * a complete removable unit or fru.
 * i.e. do these ranges belong to the same physical device,
 * s.t. if I offline all of these sections I can then
 * remove the physical device?
 */
static ssize_t show_phys_device(struct sys_device *dev,
                                struct sysdev_attribute *attr, char *buf)
{
        struct memory_block *mem =
                container_of(dev, struct memory_block, sysdev);
        return sprintf(buf, "%d\n", mem->phys_device);
}

static SYSDEV_ATTR(phys_index, 0444, show_mem_phys_index, NULL);
static SYSDEV_ATTR(state, 0644, show_mem_state, store_mem_state);
static SYSDEV_ATTR(phys_device, 0444, show_phys_device, NULL);
static SYSDEV_ATTR(removable, 0444, show_mem_removable, NULL);

#define mem_create_simple_file(mem, attr_name)  \
        sysdev_create_file(&mem->sysdev, &attr_##attr_name)
#define mem_remove_simple_file(mem, attr_name)  \
        sysdev_remove_file(&mem->sysdev, &attr_##attr_name)

/*
 * Block size attribute stuff
 */
static ssize_t
print_block_size(struct class *class, char *buf)
{
        return sprintf(buf, "%lx\n", (unsigned long)PAGES_PER_SECTION * PAGE_SIZE);
}

static CLASS_ATTR(block_size_bytes, 0444, print_block_size, NULL);

static int block_size_init(void)
{
        return sysfs_create_file(&memory_sysdev_class.kset.kobj,
                                &class_attr_block_size_bytes.attr);
}

/*
 * Some architectures will have custom drivers to do this, and
 * will not need to do it from userspace.  The fake hot-add code
 * as well as ppc64 will do all of their discovery in userspace
 * and will require this interface.
 */
#ifdef CONFIG_ARCH_MEMORY_PROBE
static ssize_t
memory_probe_store(struct class *class, const char *buf, size_t count)
{
        u64 phys_addr;
        int nid;
        int ret;

        phys_addr = simple_strtoull(buf, NULL, 0);

        nid = memory_add_physaddr_to_nid(phys_addr);
        ret = add_memory(nid, phys_addr, PAGES_PER_SECTION << PAGE_SHIFT);

        if (ret)
                count = ret;

        return count;
}
static CLASS_ATTR(probe, S_IWUSR, NULL, memory_probe_store);

static int memory_probe_init(void)
{
        return sysfs_create_file(&memory_sysdev_class.kset.kobj,
                                &class_attr_probe.attr);
}
#else
static inline int memory_probe_init(void)
{
        return 0;
}
#endif

/*
 * Note that phys_device is optional.  It is here to allow for
 * differentiation between which *physical* devices each
 * section belongs to...
 */

static int add_memory_block(int nid, struct mem_section *section,
                        unsigned long state, int phys_device,
                        enum mem_add_context context)
{
        struct memory_block *mem = kzalloc(sizeof(*mem), GFP_KERNEL);
        int ret = 0;

        if (!mem)
                return -ENOMEM;

        mem->phys_index = __section_nr(section);
        mem->state = state;
        mutex_init(&mem->state_mutex);
        mem->phys_device = phys_device;

        ret = register_memory(mem, section);
        if (!ret)
                ret = mem_create_simple_file(mem, phys_index);
        if (!ret)
                ret = mem_create_simple_file(mem, state);
        if (!ret)
                ret = mem_create_simple_file(mem, phys_device);
        if (!ret)
                ret = mem_create_simple_file(mem, removable);
        if (!ret) {
                if (context == HOTPLUG)
                        ret = register_mem_sect_under_node(mem, nid);
        }

        return ret;
}

/*
 * For now, we have a linear search to go find the appropriate
 * memory_block corresponding to a particular phys_index. If
 * this gets to be a real problem, we can always use a radix
 * tree or something here.
 *
 * This could be made generic for all sysdev classes.
 */
struct memory_block *find_memory_block(struct mem_section *section)
{
        struct kobject *kobj;
        struct sys_device *sysdev;
        struct memory_block *mem;
        char name[sizeof(MEMORY_CLASS_NAME) + 9 + 1];

        /*
         * This only works because we know that section == sysdev->id
         * slightly redundant with sysdev_register()
         */
        sprintf(&name[0], "%s%d", MEMORY_CLASS_NAME, __section_nr(section));

        kobj = kset_find_obj(&memory_sysdev_class.kset, name);
        if (!kobj)
                return NULL;

        sysdev = container_of(kobj, struct sys_device, kobj);
        mem = container_of(sysdev, struct memory_block, sysdev);

        return mem;
}

int remove_memory_block(unsigned long node_id, struct mem_section *section,
                int phys_device)
{
        struct memory_block *mem;

        mem = find_memory_block(section);
        unregister_mem_sect_under_nodes(mem);
        mem_remove_simple_file(mem, phys_index);
        mem_remove_simple_file(mem, state);
        mem_remove_simple_file(mem, phys_device);
        mem_remove_simple_file(mem, removable);
        unregister_memory(mem, section);

        return 0;
}

/*
 * need an interface for the VM to add new memory regions,
 * but without onlining it.
 */
int register_new_memory(int nid, struct mem_section *section)
{
        return add_memory_block(nid, section, MEM_OFFLINE, 0, HOTPLUG);
}

int unregister_memory_section(struct mem_section *section)
{
        if (!present_section(section))
                return -EINVAL;

        return remove_memory_block(0, section, 0);
}

/*
 * Initialize the sysfs support for memory devices...
 */
int __init memory_dev_init(void)
{
        unsigned int i;
        int ret;
        int err;

        memory_sysdev_class.kset.uevent_ops = &memory_uevent_ops;
        ret = sysdev_class_register(&memory_sysdev_class);
        if (ret)
                goto out;

        /*
         * Create entries for memory sections that were found
         * during boot and have been initialized
         */
        for (i = 0; i < NR_MEM_SECTIONS; i++) {
                if (!present_section_nr(i))
                        continue;
                err = add_memory_block(0, __nr_to_section(i), MEM_ONLINE,
                                        0, BOOT);
                if (!ret)
                        ret = err;
        }

        err = memory_probe_init();
        if (!ret)
                ret = err;
        err = block_size_init();
        if (!ret)
                ret = err;
out:
        if (ret)
                printk(KERN_ERR "%s() failed: %d\n", __func__, ret);
        return ret;
}