// SPDX-License-Identifier: GPL-2.0-or-later
/*
  * Copyright (C) 2010 Brian King IBM Corporation
  */

#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 "pseries.h"

static struct device suspend_dev;

/**
 * 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(u64 stream_id)
{
        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_enter - Final phase of hibernation
 *
 * Return value:
 *      0 on success / other on failure
 **/
static int pseries_suspend_enter(suspend_state_t state)
{
        return rtas_ibm_suspend_me(NULL);
}

/**
 * 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)
{
        u64 stream_id;
        int rc;

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

        stream_id = simple_strtoul(buf, NULL, 16);

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

        if (!rc)
                rc = pm_suspend(PM_SUSPEND_MEM);

        if (!rc) {
                rc = count;
                post_mobility_fixup();
        }


        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, 0644, show_hibernate, store_hibernate);

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

static const struct platform_suspend_ops pseries_suspend_ops = {
        .valid          = suspend_valid_only_mem,
        .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)
{
        struct device *dev_root;
        int rc;

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

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

        dev_root = bus_get_dev_root(&suspend_subsys);
        if (dev_root) {
                rc = device_create_file(dev_root, &dev_attr_hibernate);
                put_device(dev_root);
                if (rc)
                        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;

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

        suspend_set_ops(&pseries_suspend_ops);
        return 0;
}
machine_device_initcall(pseries, pseries_suspend_init);