/*
 * pseries CPU Hotplug infrastructure.
 *
 * Split out from arch/powerpc/platforms/pseries/setup.c
 *  arch/powerpc/kernel/rtas.c, and arch/powerpc/platforms/pseries/smp.c
 *
 * Peter Bergner, IBM   March 2001.
 * Copyright (C) 2001 IBM.
 * Dave Engebretsen, Peter Bergner, and
 * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com
 * Plus various changes from other IBM teams...
 *
 * Copyright (C) 2006 Michael Ellerman, 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.
 */

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

#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/sched.h>        /* for idle_task_exit */
#include <linux/sched/hotplug.h>
#include <linux/cpu.h>
#include <linux/of.h>
#include <linux/slab.h>
#include <asm/prom.h>
#include <asm/rtas.h>
#include <asm/firmware.h>
#include <asm/machdep.h>
#include <asm/vdso_datapage.h>
#include <asm/xics.h>
#include <asm/xive.h>
#include <asm/plpar_wrappers.h>

#include "pseries.h"
#include "offline_states.h"

/* This version can't take the spinlock, because it never returns */
static int rtas_stop_self_token = RTAS_UNKNOWN_SERVICE;

static DEFINE_PER_CPU(enum cpu_state_vals, preferred_offline_state) =
                                                        CPU_STATE_OFFLINE;
static DEFINE_PER_CPU(enum cpu_state_vals, current_state) = CPU_STATE_OFFLINE;

static enum cpu_state_vals default_offline_state = CPU_STATE_OFFLINE;

static bool cede_offline_enabled __read_mostly = true;

/*
 * Enable/disable cede_offline when available.
 */
static int __init setup_cede_offline(char *str)
{
        return (kstrtobool(str, &cede_offline_enabled) == 0);
}

__setup("cede_offline=", setup_cede_offline);

enum cpu_state_vals get_cpu_current_state(int cpu)
{
        return per_cpu(current_state, cpu);
}

void set_cpu_current_state(int cpu, enum cpu_state_vals state)
{
        per_cpu(current_state, cpu) = state;
}

enum cpu_state_vals get_preferred_offline_state(int cpu)
{
        return per_cpu(preferred_offline_state, cpu);
}

void set_preferred_offline_state(int cpu, enum cpu_state_vals state)
{
        per_cpu(preferred_offline_state, cpu) = state;
}

void set_default_offline_state(int cpu)
{
        per_cpu(preferred_offline_state, cpu) = default_offline_state;
}

static void rtas_stop_self(void)
{
        static struct rtas_args args;

        local_irq_disable();

        BUG_ON(rtas_stop_self_token == RTAS_UNKNOWN_SERVICE);

        printk("cpu %u (hwid %u) Ready to die...\n",
               smp_processor_id(), hard_smp_processor_id());

        rtas_call_unlocked(&args, rtas_stop_self_token, 0, 1, NULL);

        panic("Alas, I survived.\n");
}

static void pseries_mach_cpu_die(void)
{
        unsigned int cpu = smp_processor_id();
        unsigned int hwcpu = hard_smp_processor_id();
        u8 cede_latency_hint = 0;

        local_irq_disable();
        idle_task_exit();
        if (xive_enabled())
                xive_teardown_cpu();
        else
                xics_teardown_cpu();

        if (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) {
                set_cpu_current_state(cpu, CPU_STATE_INACTIVE);
                if (ppc_md.suspend_disable_cpu)
                        ppc_md.suspend_disable_cpu();

                cede_latency_hint = 2;

                get_lppaca()->idle = 1;
                if (!lppaca_shared_proc(get_lppaca()))
                        get_lppaca()->donate_dedicated_cpu = 1;

                while (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) {
                        while (!prep_irq_for_idle()) {
                                local_irq_enable();
                                local_irq_disable();
                        }

                        extended_cede_processor(cede_latency_hint);
                }

                local_irq_disable();

                if (!lppaca_shared_proc(get_lppaca()))
                        get_lppaca()->donate_dedicated_cpu = 0;
                get_lppaca()->idle = 0;

                if (get_preferred_offline_state(cpu) == CPU_STATE_ONLINE) {
                        unregister_slb_shadow(hwcpu);

                        hard_irq_disable();
                        /*
                         * Call to start_secondary_resume() will not return.
                         * Kernel stack will be reset and start_secondary()
                         * will be called to continue the online operation.
                         */
                        start_secondary_resume();
                }
        }

        /* Requested state is CPU_STATE_OFFLINE at this point */
        WARN_ON(get_preferred_offline_state(cpu) != CPU_STATE_OFFLINE);

        set_cpu_current_state(cpu, CPU_STATE_OFFLINE);
        unregister_slb_shadow(hwcpu);
        rtas_stop_self();

        /* Should never get here... */
        BUG();
        for(;;);
}

static int pseries_cpu_disable(void)
{
        int cpu = smp_processor_id();

        set_cpu_online(cpu, false);
        vdso_data->processorCount--;

        /*fix boot_cpuid here*/
        if (cpu == boot_cpuid)
                boot_cpuid = cpumask_any(cpu_online_mask);

        /* FIXME: abstract this to not be platform specific later on */
        if (xive_enabled())
                xive_smp_disable_cpu();
        else
                xics_migrate_irqs_away();
        return 0;
}

/*
 * pseries_cpu_die: Wait for the cpu to die.
 * @cpu: logical processor id of the CPU whose death we're awaiting.
 *
 * This function is called from the context of the thread which is performing
 * the cpu-offline. Here we wait for long enough to allow the cpu in question
 * to self-destroy so that the cpu-offline thread can send the CPU_DEAD
 * notifications.
 *
 * OTOH, pseries_mach_cpu_die() is called by the @cpu when it wants to
 * self-destruct.
 */
static void pseries_cpu_die(unsigned int cpu)
{
        int tries;
        int cpu_status = 1;
        unsigned int pcpu = get_hard_smp_processor_id(cpu);

        if (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) {
                cpu_status = 1;
                for (tries = 0; tries < 5000; tries++) {
                        if (get_cpu_current_state(cpu) == CPU_STATE_INACTIVE) {
                                cpu_status = 0;
                                break;
                        }
                        msleep(1);
                }
        } else if (get_preferred_offline_state(cpu) == CPU_STATE_OFFLINE) {

                for (tries = 0; tries < 25; tries++) {
                        cpu_status = smp_query_cpu_stopped(pcpu);
                        if (cpu_status == QCSS_STOPPED ||
                            cpu_status == QCSS_HARDWARE_ERROR)
                                break;
                        cpu_relax();
                }
        }

        if (cpu_status != 0) {
                printk("Querying DEAD? cpu %i (%i) shows %i\n",
                       cpu, pcpu, cpu_status);
        }

        /* Isolation and deallocation are definitely done by
         * drslot_chrp_cpu.  If they were not they would be
         * done here.  Change isolate state to Isolate and
         * change allocation-state to Unusable.
         */
        paca[cpu].cpu_start = 0;
}

/*
 * Update cpu_present_mask and paca(s) for a new cpu node.  The wrinkle
 * here is that a cpu device node may represent up to two logical cpus
 * in the SMT case.  We must honor the assumption in other code that
 * the logical ids for sibling SMT threads x and y are adjacent, such
 * that x^1 == y and y^1 == x.
 */
static int pseries_add_processor(struct device_node *np)
{
        unsigned int cpu;
        cpumask_var_t candidate_mask, tmp;
        int err = -ENOSPC, len, nthreads, i;
        const __be32 *intserv;

        intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len);
        if (!intserv)
                return 0;

        zalloc_cpumask_var(&candidate_mask, GFP_KERNEL);
        zalloc_cpumask_var(&tmp, GFP_KERNEL);

        nthreads = len / sizeof(u32);
        for (i = 0; i < nthreads; i++)
                cpumask_set_cpu(i, tmp);

        cpu_maps_update_begin();

        BUG_ON(!cpumask_subset(cpu_present_mask, cpu_possible_mask));

        /* Get a bitmap of unoccupied slots. */
        cpumask_xor(candidate_mask, cpu_possible_mask, cpu_present_mask);
        if (cpumask_empty(candidate_mask)) {
                /* If we get here, it most likely means that NR_CPUS is
                 * less than the partition's max processors setting.
                 */
                printk(KERN_ERR "Cannot add cpu %pOF; this system configuration"
                       " supports %d logical cpus.\n", np,
                       num_possible_cpus());
                goto out_unlock;
        }

        while (!cpumask_empty(tmp))
                if (cpumask_subset(tmp, candidate_mask))
                        /* Found a range where we can insert the new cpu(s) */
                        break;
                else
                        cpumask_shift_left(tmp, tmp, nthreads);

        if (cpumask_empty(tmp)) {
                printk(KERN_ERR "Unable to find space in cpu_present_mask for"
                       " processor %s with %d thread(s)\n", np->name,
                       nthreads);
                goto out_unlock;
        }

        for_each_cpu(cpu, tmp) {
                BUG_ON(cpu_present(cpu));
                set_cpu_present(cpu, true);
                set_hard_smp_processor_id(cpu, be32_to_cpu(*intserv++));
        }
        err = 0;
out_unlock:
        cpu_maps_update_done();
        free_cpumask_var(candidate_mask);
        free_cpumask_var(tmp);
        return err;
}

/*
 * Update the present map for a cpu node which is going away, and set
 * the hard id in the paca(s) to -1 to be consistent with boot time
 * convention for non-present cpus.
 */
static void pseries_remove_processor(struct device_node *np)
{
        unsigned int cpu;
        int len, nthreads, i;
        const __be32 *intserv;
        u32 thread;

        intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len);
        if (!intserv)
                return;

        nthreads = len / sizeof(u32);

        cpu_maps_update_begin();
        for (i = 0; i < nthreads; i++) {
                thread = be32_to_cpu(intserv[i]);
                for_each_present_cpu(cpu) {
                        if (get_hard_smp_processor_id(cpu) != thread)
                                continue;
                        BUG_ON(cpu_online(cpu));
                        set_cpu_present(cpu, false);
                        set_hard_smp_processor_id(cpu, -1);
                        break;
                }
                if (cpu >= nr_cpu_ids)
                        printk(KERN_WARNING "Could not find cpu to remove "
                               "with physical id 0x%x\n", thread);
        }
        cpu_maps_update_done();
}

static int dlpar_online_cpu(struct device_node *dn)
{
        int rc = 0;
        unsigned int cpu;
        int len, nthreads, i;
        const __be32 *intserv;
        u32 thread;

        intserv = of_get_property(dn, "ibm,ppc-interrupt-server#s", &len);
        if (!intserv)
                return -EINVAL;

        nthreads = len / sizeof(u32);

        cpu_maps_update_begin();
        for (i = 0; i < nthreads; i++) {
                thread = be32_to_cpu(intserv[i]);
                for_each_present_cpu(cpu) {
                        if (get_hard_smp_processor_id(cpu) != thread)
                                continue;
                        BUG_ON(get_cpu_current_state(cpu)
                                        != CPU_STATE_OFFLINE);
                        cpu_maps_update_done();
                        timed_topology_update(1);
                        rc = device_online(get_cpu_device(cpu));
                        if (rc)
                                goto out;
                        cpu_maps_update_begin();

                        break;
                }
                if (cpu == num_possible_cpus())
                        printk(KERN_WARNING "Could not find cpu to online "
                               "with physical id 0x%x\n", thread);
        }
        cpu_maps_update_done();

out:
        return rc;

}

static bool dlpar_cpu_exists(struct device_node *parent, u32 drc_index)
{
        struct device_node *child = NULL;
        u32 my_drc_index;
        bool found;
        int rc;

        /* Assume cpu doesn't exist */
        found = false;

        for_each_child_of_node(parent, child) {
                rc = of_property_read_u32(child, "ibm,my-drc-index",
                                          &my_drc_index);
                if (rc)
                        continue;

                if (my_drc_index == drc_index) {
                        of_node_put(child);
                        found = true;
                        break;
                }
        }

        return found;
}

static bool valid_cpu_drc_index(struct device_node *parent, u32 drc_index)
{
        bool found = false;
        int rc, index;

        index = 0;
        while (!found) {
                u32 drc;

                rc = of_property_read_u32_index(parent, "ibm,drc-indexes",
                                                index++, &drc);
                if (rc)
                        break;

                if (drc == drc_index)
                        found = true;
        }

        return found;
}

static ssize_t dlpar_cpu_add(u32 drc_index)
{
        struct device_node *dn, *parent;
        int rc, saved_rc;

        pr_debug("Attempting to add CPU, drc index: %x\n", drc_index);

        parent = of_find_node_by_path("/cpus");
        if (!parent) {
                pr_warn("Failed to find CPU root node \"/cpus\"\n");
                return -ENODEV;
        }

        if (dlpar_cpu_exists(parent, drc_index)) {
                of_node_put(parent);
                pr_warn("CPU with drc index %x already exists\n", drc_index);
                return -EINVAL;
        }

        if (!valid_cpu_drc_index(parent, drc_index)) {
                of_node_put(parent);
                pr_warn("Cannot find CPU (drc index %x) to add.\n", drc_index);
                return -EINVAL;
        }

        rc = dlpar_acquire_drc(drc_index);
        if (rc) {
                pr_warn("Failed to acquire DRC, rc: %d, drc index: %x\n",
                        rc, drc_index);
                of_node_put(parent);
                return -EINVAL;
        }

        dn = dlpar_configure_connector(cpu_to_be32(drc_index), parent);
        if (!dn) {
                pr_warn("Failed call to configure-connector, drc index: %x\n",
                        drc_index);
                dlpar_release_drc(drc_index);
                of_node_put(parent);
                return -EINVAL;
        }

        rc = dlpar_attach_node(dn, parent);

        /* Regardless we are done with parent now */
        of_node_put(parent);

        if (rc) {
                saved_rc = rc;
                pr_warn("Failed to attach node %s, rc: %d, drc index: %x\n",
                        dn->name, rc, drc_index);

                rc = dlpar_release_drc(drc_index);
                if (!rc)
                        dlpar_free_cc_nodes(dn);

                return saved_rc;
        }

        rc = dlpar_online_cpu(dn);
        if (rc) {
                saved_rc = rc;
                pr_warn("Failed to online cpu %s, rc: %d, drc index: %x\n",
                        dn->name, rc, drc_index);

                rc = dlpar_detach_node(dn);
                if (!rc)
                        dlpar_release_drc(drc_index);

                return saved_rc;
        }

        pr_debug("Successfully added CPU %s, drc index: %x\n", dn->name,
                 drc_index);
        return rc;
}

static int dlpar_offline_cpu(struct device_node *dn)
{
        int rc = 0;
        unsigned int cpu;
        int len, nthreads, i;
        const __be32 *intserv;
        u32 thread;

        intserv = of_get_property(dn, "ibm,ppc-interrupt-server#s", &len);
        if (!intserv)
                return -EINVAL;

        nthreads = len / sizeof(u32);

        cpu_maps_update_begin();
        for (i = 0; i < nthreads; i++) {
                thread = be32_to_cpu(intserv[i]);
                for_each_present_cpu(cpu) {
                        if (get_hard_smp_processor_id(cpu) != thread)
                                continue;

                        if (get_cpu_current_state(cpu) == CPU_STATE_OFFLINE)
                                break;

                        if (get_cpu_current_state(cpu) == CPU_STATE_ONLINE) {
                                set_preferred_offline_state(cpu,
                                                            CPU_STATE_OFFLINE);
                                cpu_maps_update_done();
                                timed_topology_update(1);
                                rc = device_offline(get_cpu_device(cpu));
                                if (rc)
                                        goto out;
                                cpu_maps_update_begin();
                                break;

                        }

                        /*
                         * The cpu is in CPU_STATE_INACTIVE.
                         * Upgrade it's state to CPU_STATE_OFFLINE.
                         */
                        set_preferred_offline_state(cpu, CPU_STATE_OFFLINE);
                        BUG_ON(plpar_hcall_norets(H_PROD, thread)
                                                                != H_SUCCESS);
                        __cpu_die(cpu);
                        break;
                }
                if (cpu == num_possible_cpus())
                        printk(KERN_WARNING "Could not find cpu to offline with physical id 0x%x\n", thread);
        }
        cpu_maps_update_done();

out:
        return rc;

}

static ssize_t dlpar_cpu_remove(struct device_node *dn, u32 drc_index)
{
        int rc;

        pr_debug("Attempting to remove CPU %s, drc index: %x\n",
                 dn->name, drc_index);

        rc = dlpar_offline_cpu(dn);
        if (rc) {
                pr_warn("Failed to offline CPU %s, rc: %d\n", dn->name, rc);
                return -EINVAL;
        }

        rc = dlpar_release_drc(drc_index);
        if (rc) {
                pr_warn("Failed to release drc (%x) for CPU %s, rc: %d\n",
                        drc_index, dn->name, rc);
                dlpar_online_cpu(dn);
                return rc;
        }

        rc = dlpar_detach_node(dn);
        if (rc) {
                int saved_rc = rc;

                pr_warn("Failed to detach CPU %s, rc: %d", dn->name, rc);

                rc = dlpar_acquire_drc(drc_index);
                if (!rc)
                        dlpar_online_cpu(dn);

                return saved_rc;
        }

        pr_debug("Successfully removed CPU, drc index: %x\n", drc_index);
        return 0;
}

static struct device_node *cpu_drc_index_to_dn(u32 drc_index)
{
        struct device_node *dn;
        u32 my_index;
        int rc;

        for_each_node_by_type(dn, "cpu") {
                rc = of_property_read_u32(dn, "ibm,my-drc-index", &my_index);
                if (rc)
                        continue;

                if (my_index == drc_index)
                        break;
        }

        return dn;
}

static int dlpar_cpu_remove_by_index(u32 drc_index)
{
        struct device_node *dn;
        int rc;

        dn = cpu_drc_index_to_dn(drc_index);
        if (!dn) {
                pr_warn("Cannot find CPU (drc index %x) to remove\n",
                        drc_index);
                return -ENODEV;
        }

        rc = dlpar_cpu_remove(dn, drc_index);
        of_node_put(dn);
        return rc;
}

static int find_dlpar_cpus_to_remove(u32 *cpu_drcs, int cpus_to_remove)
{
        struct device_node *dn;
        int cpus_found = 0;
        int rc;

        /* We want to find cpus_to_remove + 1 CPUs to ensure we do not
         * remove the last CPU.
         */
        for_each_node_by_type(dn, "cpu") {
                cpus_found++;

                if (cpus_found > cpus_to_remove) {
                        of_node_put(dn);
                        break;
                }

                /* Note that cpus_found is always 1 ahead of the index
                 * into the cpu_drcs array, so we use cpus_found - 1
                 */
                rc = of_property_read_u32(dn, "ibm,my-drc-index",
                                          &cpu_drcs[cpus_found - 1]);
                if (rc) {
                        pr_warn("Error occurred getting drc-index for %s\n",
                                dn->name);
                        of_node_put(dn);
                        return -1;
                }
        }

        if (cpus_found < cpus_to_remove) {
                pr_warn("Failed to find enough CPUs (%d of %d) to remove\n",
                        cpus_found, cpus_to_remove);
        } else if (cpus_found == cpus_to_remove) {
                pr_warn("Cannot remove all CPUs\n");
        }

        return cpus_found;
}

static int dlpar_cpu_remove_by_count(u32 cpus_to_remove)
{
        u32 *cpu_drcs;
        int cpus_found;
        int cpus_removed = 0;
        int i, rc;

        pr_debug("Attempting to hot-remove %d CPUs\n", cpus_to_remove);

        cpu_drcs = kcalloc(cpus_to_remove, sizeof(*cpu_drcs), GFP_KERNEL);
        if (!cpu_drcs)
                return -EINVAL;

        cpus_found = find_dlpar_cpus_to_remove(cpu_drcs, cpus_to_remove);
        if (cpus_found <= cpus_to_remove) {
                kfree(cpu_drcs);
                return -EINVAL;
        }

        for (i = 0; i < cpus_to_remove; i++) {
                rc = dlpar_cpu_remove_by_index(cpu_drcs[i]);
                if (rc)
                        break;

                cpus_removed++;
        }

        if (cpus_removed != cpus_to_remove) {
                pr_warn("CPU hot-remove failed, adding back removed CPUs\n");

                for (i = 0; i < cpus_removed; i++)
                        dlpar_cpu_add(cpu_drcs[i]);

                rc = -EINVAL;
        } else {
                rc = 0;
        }

        kfree(cpu_drcs);
        return rc;
}

static int find_dlpar_cpus_to_add(u32 *cpu_drcs, u32 cpus_to_add)
{
        struct device_node *parent;
        int cpus_found = 0;
        int index, rc;

        parent = of_find_node_by_path("/cpus");
        if (!parent) {
                pr_warn("Could not find CPU root node in device tree\n");
                kfree(cpu_drcs);
                return -1;
        }

        /* Search the ibm,drc-indexes array for possible CPU drcs to
         * add. Note that the format of the ibm,drc-indexes array is
         * the number of entries in the array followed by the array
         * of drc values so we start looking at index = 1.
         */
        index = 1;
        while (cpus_found < cpus_to_add) {
                u32 drc;

                rc = of_property_read_u32_index(parent, "ibm,drc-indexes",
                                                index++, &drc);
                if (rc)
                        break;

                if (dlpar_cpu_exists(parent, drc))
                        continue;

                cpu_drcs[cpus_found++] = drc;
        }

        of_node_put(parent);
        return cpus_found;
}

static int dlpar_cpu_add_by_count(u32 cpus_to_add)
{
        u32 *cpu_drcs;
        int cpus_added = 0;
        int cpus_found;
        int i, rc;

        pr_debug("Attempting to hot-add %d CPUs\n", cpus_to_add);

        cpu_drcs = kcalloc(cpus_to_add, sizeof(*cpu_drcs), GFP_KERNEL);
        if (!cpu_drcs)
                return -EINVAL;

        cpus_found = find_dlpar_cpus_to_add(cpu_drcs, cpus_to_add);
        if (cpus_found < cpus_to_add) {
                pr_warn("Failed to find enough CPUs (%d of %d) to add\n",
                        cpus_found, cpus_to_add);
                kfree(cpu_drcs);
                return -EINVAL;
        }

        for (i = 0; i < cpus_to_add; i++) {
                rc = dlpar_cpu_add(cpu_drcs[i]);
                if (rc)
                        break;

                cpus_added++;
        }

        if (cpus_added < cpus_to_add) {
                pr_warn("CPU hot-add failed, removing any added CPUs\n");

                for (i = 0; i < cpus_added; i++)
                        dlpar_cpu_remove_by_index(cpu_drcs[i]);

                rc = -EINVAL;
        } else {
                rc = 0;
        }

        kfree(cpu_drcs);
        return rc;
}

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

        count = hp_elog->_drc_u.drc_count;
        drc_index = hp_elog->_drc_u.drc_index;

        lock_device_hotplug();

        switch (hp_elog->action) {
        case PSERIES_HP_ELOG_ACTION_REMOVE:
                if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_COUNT)
                        rc = dlpar_cpu_remove_by_count(count);
                else if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_INDEX)
                        rc = dlpar_cpu_remove_by_index(drc_index);
                else
                        rc = -EINVAL;
                break;
        case PSERIES_HP_ELOG_ACTION_ADD:
                if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_COUNT)
                        rc = dlpar_cpu_add_by_count(count);
                else if (hp_elog->id_type == PSERIES_HP_ELOG_ID_DRC_INDEX)
                        rc = dlpar_cpu_add(drc_index);
                else
                        rc = -EINVAL;
                break;
        default:
                pr_err("Invalid action (%d) specified\n", hp_elog->action);
                rc = -EINVAL;
                break;
        }

        unlock_device_hotplug();
        return rc;
}

#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE

static ssize_t dlpar_cpu_probe(const char *buf, size_t count)
{
        u32 drc_index;
        int rc;

        rc = kstrtou32(buf, 0, &drc_index);
        if (rc)
                return -EINVAL;

        rc = dlpar_cpu_add(drc_index);

        return rc ? rc : count;
}

static ssize_t dlpar_cpu_release(const char *buf, size_t count)
{
        struct device_node *dn;
        u32 drc_index;
        int rc;

        dn = of_find_node_by_path(buf);
        if (!dn)
                return -EINVAL;

        rc = of_property_read_u32(dn, "ibm,my-drc-index", &drc_index);
        if (rc) {
                of_node_put(dn);
                return -EINVAL;
        }

        rc = dlpar_cpu_remove(dn, drc_index);
        of_node_put(dn);

        return rc ? rc : count;
}

#endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */

static int pseries_smp_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_processor(rd->dn);
                break;
        case OF_RECONFIG_DETACH_NODE:
                pseries_remove_processor(rd->dn);
                break;
        }
        return notifier_from_errno(err);
}

static struct notifier_block pseries_smp_nb = {
        .notifier_call = pseries_smp_notifier,
};

#define MAX_CEDE_LATENCY_LEVELS         4
#define CEDE_LATENCY_PARAM_LENGTH       10
#define CEDE_LATENCY_PARAM_MAX_LENGTH   \
        (MAX_CEDE_LATENCY_LEVELS * CEDE_LATENCY_PARAM_LENGTH * sizeof(char))
#define CEDE_LATENCY_TOKEN              45

static char cede_parameters[CEDE_LATENCY_PARAM_MAX_LENGTH];

static int parse_cede_parameters(void)
{
        memset(cede_parameters, 0, CEDE_LATENCY_PARAM_MAX_LENGTH);
        return rtas_call(rtas_token("ibm,get-system-parameter"), 3, 1,
                         NULL,
                         CEDE_LATENCY_TOKEN,
                         __pa(cede_parameters),
                         CEDE_LATENCY_PARAM_MAX_LENGTH);
}

static int __init pseries_cpu_hotplug_init(void)
{
        int cpu;
        int qcss_tok;

#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
        ppc_md.cpu_probe = dlpar_cpu_probe;
        ppc_md.cpu_release = dlpar_cpu_release;
#endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */

        rtas_stop_self_token = rtas_token("stop-self");
        qcss_tok = rtas_token("query-cpu-stopped-state");

        if (rtas_stop_self_token == RTAS_UNKNOWN_SERVICE ||
                        qcss_tok == RTAS_UNKNOWN_SERVICE) {
                printk(KERN_INFO "CPU Hotplug not supported by firmware "
                                "- disabling.\n");
                return 0;
        }

        ppc_md.cpu_die = pseries_mach_cpu_die;
        smp_ops->cpu_disable = pseries_cpu_disable;
        smp_ops->cpu_die = pseries_cpu_die;

        /* Processors can be added/removed only on LPAR */
        if (firmware_has_feature(FW_FEATURE_LPAR)) {
                of_reconfig_notifier_register(&pseries_smp_nb);
                cpu_maps_update_begin();
                if (cede_offline_enabled && parse_cede_parameters() == 0) {
                        default_offline_state = CPU_STATE_INACTIVE;
                        for_each_online_cpu(cpu)
                                set_default_offline_state(cpu);
                }
                cpu_maps_update_done();
        }

        return 0;
}
machine_arch_initcall(pseries, pseries_cpu_hotplug_init);