/*
  * Copyright (C) 2010 Brian King 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.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  */

#include <linux/cpu.h>
#include <linux/delay.h>
#include <linux/suspend.h>
#include <linux/stat.h>
#include <asm/firmware.h>
#include <asm/hvcall.h>
#include <asm/machdep.h>
#include <asm/mmu.h>
#include <asm/rtas.h>
#include <asm/topology.h>
#include "../../kernel/cacheinfo.h"

static u64 stream_id;
static struct device suspend_dev;
static DECLARE_COMPLETION(suspend_work);
static struct rtas_suspend_me_data suspend_data;
static atomic_t suspending;

/**
 * pseries_suspend_begin - First phase of hibernation
 *
 * Check to ensure we are in a valid state to hibernate
 *
 * Return value:
 *      0 on success / other on failure
 **/
static int pseries_suspend_begin(suspend_state_t state)
{
        long vasi_state, rc;
        unsigned long retbuf[PLPAR_HCALL_BUFSIZE];

        /* Make sure the state is valid */
        rc = plpar_hcall(H_VASI_STATE, retbuf, stream_id);

        vasi_state = retbuf[0];

        if (rc) {
                pr_err("pseries_suspend_begin: vasi_state returned %ld\n",rc);
                return rc;
        } else if (vasi_state == H_VASI_ENABLED) {
                return -EAGAIN;
        } else if (vasi_state != H_VASI_SUSPENDING) {
                pr_err("pseries_suspend_begin: vasi_state returned state %ld\n",
                       vasi_state);
                return -EIO;
        }

        return 0;
}

/**
 * pseries_suspend_cpu - Suspend a single CPU
 *
 * Makes the H_JOIN call to suspend the CPU
 *
 **/
static int pseries_suspend_cpu(void)
{
        if (atomic_read(&suspending))
                return rtas_suspend_cpu(&suspend_data);
        return 0;
}

/**
 * pseries_suspend_enable_irqs
 *
 * Post suspend configuration updates
 *
 **/
static void pseries_suspend_enable_irqs(void)
{
        /*
         * Update configuration which can be modified based on device tree
         * changes during resume.
         */
        cacheinfo_cpu_offline(smp_processor_id());
        post_mobility_fixup();
        cacheinfo_cpu_online(smp_processor_id());
}

/**
 * pseries_suspend_enter - Final phase of hibernation
 *
 * Return value:
 *      0 on success / other on failure
 **/
static int pseries_suspend_enter(suspend_state_t state)
{
        int rc = rtas_suspend_last_cpu(&suspend_data);

        atomic_set(&suspending, 0);
        atomic_set(&suspend_data.done, 1);
        return rc;
}

/**
 * pseries_prepare_late - Prepare to suspend all other CPUs
 *
 * Return value:
 *      0 on success / other on failure
 **/
static int pseries_prepare_late(void)
{
        atomic_set(&suspending, 1);
        atomic_set(&suspend_data.working, 0);
        atomic_set(&suspend_data.done, 0);
        atomic_set(&suspend_data.error, 0);
        suspend_data.complete = &suspend_work;
        reinit_completion(&suspend_work);
        return 0;
}

/**
 * store_hibernate - Initiate partition hibernation
 * @dev:                subsys root device
 * @attr:               device attribute struct
 * @buf:                buffer
 * @count:              buffer size
 *
 * Write the stream ID received from the HMC to this file
 * to trigger hibernating the partition
 *
 * Return value:
 *      number of bytes printed to buffer / other on failure
 **/
static ssize_t store_hibernate(struct device *dev,
                               struct device_attribute *attr,
                               const char *buf, size_t count)
{
        cpumask_var_t offline_mask;
        int rc;

        if (!capable(CAP_SYS_ADMIN))
                return -EPERM;

        if (!alloc_cpumask_var(&offline_mask, GFP_TEMPORARY))
                return -ENOMEM;

        stream_id = simple_strtoul(buf, NULL, 16);

        do {
                rc = pseries_suspend_begin(PM_SUSPEND_MEM);
                if (rc == -EAGAIN)
                        ssleep(1);
        } while (rc == -EAGAIN);

        if (!rc) {
                /* All present CPUs must be online */
                cpumask_andnot(offline_mask, cpu_present_mask,
                                cpu_online_mask);
                rc = rtas_online_cpus_mask(offline_mask);
                if (rc) {
                        pr_err("%s: Could not bring present CPUs online.\n",
                                        __func__);
                        goto out;
                }

                stop_topology_update();
                rc = pm_suspend(PM_SUSPEND_MEM);
                start_topology_update();

                /* Take down CPUs not online prior to suspend */
                if (!rtas_offline_cpus_mask(offline_mask))
                        pr_warn("%s: Could not restore CPUs to offline "
                                        "state.\n", __func__);
        }

        stream_id = 0;

        if (!rc)
                rc = count;
out:
        free_cpumask_var(offline_mask);
        return rc;
}

#define USER_DT_UPDATE  0
#define KERN_DT_UPDATE  1

/**
 * show_hibernate - Report device tree update responsibilty
 * @dev:                subsys root device
 * @attr:               device attribute struct
 * @buf:                buffer
 *
 * Report whether a device tree update is performed by the kernel after a
 * resume, or if drmgr must coordinate the update from user space.
 *
 * Return value:
 *      0 if drmgr is to initiate update, and 1 otherwise
 **/
static ssize_t show_hibernate(struct device *dev,
                              struct device_attribute *attr,
                              char *buf)
{
        return sprintf(buf, "%d\n", KERN_DT_UPDATE);
}

static DEVICE_ATTR(hibernate, S_IWUSR | S_IRUGO,
                   show_hibernate, store_hibernate);

static struct bus_type suspend_subsys = {
        .name = "power",
        .dev_name = "power",
};

static const struct platform_suspend_ops pseries_suspend_ops = {
        .valid          = suspend_valid_only_mem,
        .begin          = pseries_suspend_begin,
        .prepare_late   = pseries_prepare_late,
        .enter          = pseries_suspend_enter,
};

/**
 * pseries_suspend_sysfs_register - Register with sysfs
 *
 * Return value:
 *      0 on success / other on failure
 **/
static int pseries_suspend_sysfs_register(struct device *dev)
{
        int rc;

        if ((rc = subsys_system_register(&suspend_subsys, NULL)))
                return rc;

        dev->id = 0;
        dev->bus = &suspend_subsys;

        if ((rc = device_create_file(suspend_subsys.dev_root, &dev_attr_hibernate)))
                goto subsys_unregister;

        return 0;

subsys_unregister:
        bus_unregister(&suspend_subsys);
        return rc;
}

/**
 * pseries_suspend_init - initcall for pSeries suspend
 *
 * Return value:
 *      0 on success / other on failure
 **/
static int __init pseries_suspend_init(void)
{
        int rc;

        if (!firmware_has_feature(FW_FEATURE_LPAR))
                return 0;

        suspend_data.token = rtas_token("ibm,suspend-me");
        if (suspend_data.token == RTAS_UNKNOWN_SERVICE)
                return 0;

        if ((rc = pseries_suspend_sysfs_register(&suspend_dev)))
                return rc;

        ppc_md.suspend_disable_cpu = pseries_suspend_cpu;
        ppc_md.suspend_enable_irqs = pseries_suspend_enable_irqs;
        suspend_set_ops(&pseries_suspend_ops);
        return 0;
}
machine_device_initcall(pseries, pseries_suspend_init);