// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright IBM Corp. 2006, 2012
 * Author(s): Cornelia Huck <cornelia.huck@de.ibm.com>
 *            Martin Schwidefsky <schwidefsky@de.ibm.com>
 *            Ralph Wuerthner <rwuerthn@de.ibm.com>
 *            Felix Beck <felix.beck@de.ibm.com>
 *            Holger Dengler <hd@linux.vnet.ibm.com>
 *
 * Adjunct processor bus.
 */

#define KMSG_COMPONENT "ap"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt

#include <linux/kernel_stat.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/workqueue.h>
#include <linux/slab.h>
#include <linux/notifier.h>
#include <linux/kthread.h>
#include <linux/mutex.h>
#include <linux/suspend.h>
#include <asm/reset.h>
#include <asm/airq.h>
#include <linux/atomic.h>
#include <asm/isc.h>
#include <linux/hrtimer.h>
#include <linux/ktime.h>
#include <asm/facility.h>
#include <linux/crypto.h>
#include <linux/mod_devicetable.h>
#include <linux/debugfs.h>

#include "ap_bus.h"
#include "ap_asm.h"
#include "ap_debug.h"

/*
 * Module parameters; note though this file itself isn't modular.
 */
int ap_domain_index = -1;       /* Adjunct Processor Domain Index */
static DEFINE_SPINLOCK(ap_domain_lock);
module_param_named(domain, ap_domain_index, int, S_IRUSR|S_IRGRP);
MODULE_PARM_DESC(domain, "domain index for ap devices");
EXPORT_SYMBOL(ap_domain_index);

static int ap_thread_flag = 0;
module_param_named(poll_thread, ap_thread_flag, int, S_IRUSR|S_IRGRP);
MODULE_PARM_DESC(poll_thread, "Turn on/off poll thread, default is 0 (off).");

static struct device *ap_root_device;

DEFINE_SPINLOCK(ap_list_lock);
LIST_HEAD(ap_card_list);

static struct ap_config_info *ap_configuration;
static bool initialised;

/*
 * AP bus related debug feature things.
 */
debug_info_t *ap_dbf_info;

/*
 * Workqueue timer for bus rescan.
 */
static struct timer_list ap_config_timer;
static int ap_config_time = AP_CONFIG_TIME;
static void ap_scan_bus(struct work_struct *);
static DECLARE_WORK(ap_scan_work, ap_scan_bus);

/*
 * Tasklet & timer for AP request polling and interrupts
 */
static void ap_tasklet_fn(unsigned long);
static DECLARE_TASKLET(ap_tasklet, ap_tasklet_fn, 0);
static DECLARE_WAIT_QUEUE_HEAD(ap_poll_wait);
static struct task_struct *ap_poll_kthread = NULL;
static DEFINE_MUTEX(ap_poll_thread_mutex);
static DEFINE_SPINLOCK(ap_poll_timer_lock);
static struct hrtimer ap_poll_timer;
/* In LPAR poll with 4kHz frequency. Poll every 250000 nanoseconds.
 * If z/VM change to 1500000 nanoseconds to adjust to z/VM polling.*/
static unsigned long long poll_timeout = 250000;

/* Suspend flag */
static int ap_suspend_flag;
/* Maximum domain id */
static int ap_max_domain_id;
/* Flag to check if domain was set through module parameter domain=. This is
 * important when supsend and resume is done in a z/VM environment where the
 * domain might change. */
static int user_set_domain = 0;
static struct bus_type ap_bus_type;

/* Adapter interrupt definitions */
static void ap_interrupt_handler(struct airq_struct *airq);

static int ap_airq_flag;

static struct airq_struct ap_airq = {
        .handler = ap_interrupt_handler,
        .isc = AP_ISC,
};

/**
 * ap_using_interrupts() - Returns non-zero if interrupt support is
 * available.
 */
static inline int ap_using_interrupts(void)
{
        return ap_airq_flag;
}

/**
 * ap_airq_ptr() - Get the address of the adapter interrupt indicator
 *
 * Returns the address of the local-summary-indicator of the adapter
 * interrupt handler for AP, or NULL if adapter interrupts are not
 * available.
 */
void *ap_airq_ptr(void)
{
        if (ap_using_interrupts())
                return ap_airq.lsi_ptr;
        return NULL;
}

/**
 * ap_interrupts_available(): Test if AP interrupts are available.
 *
 * Returns 1 if AP interrupts are available.
 */
static int ap_interrupts_available(void)
{
        return test_facility(65);
}

/**
 * ap_configuration_available(): Test if AP configuration
 * information is available.
 *
 * Returns 1 if AP configuration information is available.
 */
static int ap_configuration_available(void)
{
        return test_facility(12);
}

/**
 * ap_apft_available(): Test if AP facilities test (APFT)
 * facility is available.
 *
 * Returns 1 if APFT is is available.
 */
static int ap_apft_available(void)
{
        return test_facility(15);
}

/*
 * ap_qact_available(): Test if the PQAP(QACT) subfunction is available.
 *
 * Returns 1 if the QACT subfunction is available.
 */
static inline int ap_qact_available(void)
{
        if (ap_configuration)
                return ap_configuration->qact;
        return 0;
}

/**
 * ap_test_queue(): Test adjunct processor queue.
 * @qid: The AP queue number
 * @tbit: Test facilities bit
 * @info: Pointer to queue descriptor
 *
 * Returns AP queue status structure.
 */
struct ap_queue_status ap_test_queue(ap_qid_t qid,
                                     int tbit,
                                     unsigned long *info)
{
        if (tbit)
                qid |= 1UL << 23; /* set T bit*/
        return ap_tapq(qid, info);
}
EXPORT_SYMBOL(ap_test_queue);

/*
 * ap_query_configuration(): Fetch cryptographic config info
 *
 * Returns the ap configuration info fetched via PQAP(QCI).
 * On success 0 is returned, on failure a negative errno
 * is returned, e.g. if the PQAP(QCI) instruction is not
 * available, the return value will be -EOPNOTSUPP.
 */
int ap_query_configuration(struct ap_config_info *info)
{
        if (!ap_configuration_available())
                return -EOPNOTSUPP;
        if (!info)
                return -EINVAL;
        return ap_qci(info);
}
EXPORT_SYMBOL(ap_query_configuration);

/**
 * ap_init_configuration(): Allocate and query configuration array.
 */
static void ap_init_configuration(void)
{
        if (!ap_configuration_available())
                return;

        ap_configuration = kzalloc(sizeof(*ap_configuration), GFP_KERNEL);
        if (!ap_configuration)
                return;
        if (ap_query_configuration(ap_configuration) != 0) {
                kfree(ap_configuration);
                ap_configuration = NULL;
                return;
        }
}

/*
 * ap_test_config(): helper function to extract the nrth bit
 *                   within the unsigned int array field.
 */
static inline int ap_test_config(unsigned int *field, unsigned int nr)
{
        return ap_test_bit((field + (nr >> 5)), (nr & 0x1f));
}

/*
 * ap_test_config_card_id(): Test, whether an AP card ID is configured.
 * @id AP card ID
 *
 * Returns 0 if the card is not configured
 *         1 if the card is configured or
 *           if the configuration information is not available
 */
static inline int ap_test_config_card_id(unsigned int id)
{
        if (!ap_configuration)  /* QCI not supported */
                return 1;
        return ap_test_config(ap_configuration->apm, id);
}

/*
 * ap_test_config_domain(): Test, whether an AP usage domain is configured.
 * @domain AP usage domain ID
 *
 * Returns 0 if the usage domain is not configured
 *         1 if the usage domain is configured or
 *           if the configuration information is not available
 */
static inline int ap_test_config_domain(unsigned int domain)
{
        if (!ap_configuration)  /* QCI not supported */
                return domain < 16;
        return ap_test_config(ap_configuration->aqm, domain);
}

/**
 * ap_query_queue(): Check if an AP queue is available.
 * @qid: The AP queue number
 * @queue_depth: Pointer to queue depth value
 * @device_type: Pointer to device type value
 * @facilities: Pointer to facility indicator
 */
static int ap_query_queue(ap_qid_t qid, int *queue_depth, int *device_type,
                          unsigned int *facilities)
{
        struct ap_queue_status status;
        unsigned long info;
        int nd;

        if (!ap_test_config_card_id(AP_QID_CARD(qid)))
                return -ENODEV;

        status = ap_test_queue(qid, ap_apft_available(), &info);
        switch (status.response_code) {
        case AP_RESPONSE_NORMAL:
                *queue_depth = (int)(info & 0xff);
                *device_type = (int)((info >> 24) & 0xff);
                *facilities = (unsigned int)(info >> 32);
                /* Update maximum domain id */
                nd = (info >> 16) & 0xff;
                /* if N bit is available, z13 and newer */
                if ((info & (1UL << 57)) && nd > 0)
                        ap_max_domain_id = nd;
                else /* older machine types */
                        ap_max_domain_id = 15;
                switch (*device_type) {
                        /* For CEX2 and CEX3 the available functions
                         * are not refrected by the facilities bits.
                         * Instead it is coded into the type. So here
                         * modify the function bits based on the type.
                         */
                case AP_DEVICE_TYPE_CEX2A:
                case AP_DEVICE_TYPE_CEX3A:
                        *facilities |= 0x08000000;
                        break;
                case AP_DEVICE_TYPE_CEX2C:
                case AP_DEVICE_TYPE_CEX3C:
                        *facilities |= 0x10000000;
                        break;
                default:
                        break;
                }
                return 0;
        case AP_RESPONSE_Q_NOT_AVAIL:
        case AP_RESPONSE_DECONFIGURED:
        case AP_RESPONSE_CHECKSTOPPED:
        case AP_RESPONSE_INVALID_ADDRESS:
                return -ENODEV;
        case AP_RESPONSE_RESET_IN_PROGRESS:
        case AP_RESPONSE_OTHERWISE_CHANGED:
        case AP_RESPONSE_BUSY:
                return -EBUSY;
        default:
                BUG();
        }
}

void ap_wait(enum ap_wait wait)
{
        ktime_t hr_time;

        switch (wait) {
        case AP_WAIT_AGAIN:
        case AP_WAIT_INTERRUPT:
                if (ap_using_interrupts())
                        break;
                if (ap_poll_kthread) {
                        wake_up(&ap_poll_wait);
                        break;
                }
                /* Fall through */
        case AP_WAIT_TIMEOUT:
                spin_lock_bh(&ap_poll_timer_lock);
                if (!hrtimer_is_queued(&ap_poll_timer)) {
                        hr_time = poll_timeout;
                        hrtimer_forward_now(&ap_poll_timer, hr_time);
                        hrtimer_restart(&ap_poll_timer);
                }
                spin_unlock_bh(&ap_poll_timer_lock);
                break;
        case AP_WAIT_NONE:
        default:
                break;
        }
}

/**
 * ap_request_timeout(): Handling of request timeouts
 * @t: timer making this callback
 *
 * Handles request timeouts.
 */
void ap_request_timeout(struct timer_list *t)
{
        struct ap_queue *aq = from_timer(aq, t, timeout);

        if (ap_suspend_flag)
                return;
        spin_lock_bh(&aq->lock);
        ap_wait(ap_sm_event(aq, AP_EVENT_TIMEOUT));
        spin_unlock_bh(&aq->lock);
}

/**
 * ap_poll_timeout(): AP receive polling for finished AP requests.
 * @unused: Unused pointer.
 *
 * Schedules the AP tasklet using a high resolution timer.
 */
static enum hrtimer_restart ap_poll_timeout(struct hrtimer *unused)
{
        if (!ap_suspend_flag)
                tasklet_schedule(&ap_tasklet);
        return HRTIMER_NORESTART;
}

/**
 * ap_interrupt_handler() - Schedule ap_tasklet on interrupt
 * @airq: pointer to adapter interrupt descriptor
 */
static void ap_interrupt_handler(struct airq_struct *airq)
{
        inc_irq_stat(IRQIO_APB);
        if (!ap_suspend_flag)
                tasklet_schedule(&ap_tasklet);
}

/**
 * ap_tasklet_fn(): Tasklet to poll all AP devices.
 * @dummy: Unused variable
 *
 * Poll all AP devices on the bus.
 */
static void ap_tasklet_fn(unsigned long dummy)
{
        struct ap_card *ac;
        struct ap_queue *aq;
        enum ap_wait wait = AP_WAIT_NONE;

        /* Reset the indicator if interrupts are used. Thus new interrupts can
         * be received. Doing it in the beginning of the tasklet is therefor
         * important that no requests on any AP get lost.
         */
        if (ap_using_interrupts())
                xchg(ap_airq.lsi_ptr, 0);

        spin_lock_bh(&ap_list_lock);
        for_each_ap_card(ac) {
                for_each_ap_queue(aq, ac) {
                        spin_lock_bh(&aq->lock);
                        wait = min(wait, ap_sm_event_loop(aq, AP_EVENT_POLL));
                        spin_unlock_bh(&aq->lock);
                }
        }
        spin_unlock_bh(&ap_list_lock);

        ap_wait(wait);
}

static int ap_pending_requests(void)
{
        struct ap_card *ac;
        struct ap_queue *aq;

        spin_lock_bh(&ap_list_lock);
        for_each_ap_card(ac) {
                for_each_ap_queue(aq, ac) {
                        if (aq->queue_count == 0)
                                continue;
                        spin_unlock_bh(&ap_list_lock);
                        return 1;
                }
        }
        spin_unlock_bh(&ap_list_lock);
        return 0;
}

/**
 * ap_poll_thread(): Thread that polls for finished requests.
 * @data: Unused pointer
 *
 * AP bus poll thread. The purpose of this thread is to poll for
 * finished requests in a loop if there is a "free" cpu - that is
 * a cpu that doesn't have anything better to do. The polling stops
 * as soon as there is another task or if all messages have been
 * delivered.
 */
static int ap_poll_thread(void *data)
{
        DECLARE_WAITQUEUE(wait, current);

        set_user_nice(current, MAX_NICE);
        set_freezable();
        while (!kthread_should_stop()) {
                add_wait_queue(&ap_poll_wait, &wait);
                set_current_state(TASK_INTERRUPTIBLE);
                if (ap_suspend_flag || !ap_pending_requests()) {
                        schedule();
                        try_to_freeze();
                }
                set_current_state(TASK_RUNNING);
                remove_wait_queue(&ap_poll_wait, &wait);
                if (need_resched()) {
                        schedule();
                        try_to_freeze();
                        continue;
                }
                ap_tasklet_fn(0);
        }

        return 0;
}

static int ap_poll_thread_start(void)
{
        int rc;

        if (ap_using_interrupts() || ap_poll_kthread)
                return 0;
        mutex_lock(&ap_poll_thread_mutex);
        ap_poll_kthread = kthread_run(ap_poll_thread, NULL, "appoll");
        rc = PTR_RET(ap_poll_kthread);
        if (rc)
                ap_poll_kthread = NULL;
        mutex_unlock(&ap_poll_thread_mutex);
        return rc;
}

static void ap_poll_thread_stop(void)
{
        if (!ap_poll_kthread)
                return;
        mutex_lock(&ap_poll_thread_mutex);
        kthread_stop(ap_poll_kthread);
        ap_poll_kthread = NULL;
        mutex_unlock(&ap_poll_thread_mutex);
}

#define is_card_dev(x) ((x)->parent == ap_root_device)
#define is_queue_dev(x) ((x)->parent != ap_root_device)

/**
 * ap_bus_match()
 * @dev: Pointer to device
 * @drv: Pointer to device_driver
 *
 * AP bus driver registration/unregistration.
 */
static int ap_bus_match(struct device *dev, struct device_driver *drv)
{
        struct ap_driver *ap_drv = to_ap_drv(drv);
        struct ap_device_id *id;

        /*
         * Compare device type of the device with the list of
         * supported types of the device_driver.
         */
        for (id = ap_drv->ids; id->match_flags; id++) {
                if (is_card_dev(dev) &&
                    id->match_flags & AP_DEVICE_ID_MATCH_CARD_TYPE &&
                    id->dev_type == to_ap_dev(dev)->device_type)
                        return 1;
                if (is_queue_dev(dev) &&
                    id->match_flags & AP_DEVICE_ID_MATCH_QUEUE_TYPE &&
                    id->dev_type == to_ap_dev(dev)->device_type)
                        return 1;
        }
        return 0;
}

/**
 * ap_uevent(): Uevent function for AP devices.
 * @dev: Pointer to device
 * @env: Pointer to kobj_uevent_env
 *
 * It sets up a single environment variable DEV_TYPE which contains the
 * hardware device type.
 */
static int ap_uevent (struct device *dev, struct kobj_uevent_env *env)
{
        struct ap_device *ap_dev = to_ap_dev(dev);
        int retval = 0;

        if (!ap_dev)
                return -ENODEV;

        /* Set up DEV_TYPE environment variable. */
        retval = add_uevent_var(env, "DEV_TYPE=%04X", ap_dev->device_type);
        if (retval)
                return retval;

        /* Add MODALIAS= */
        retval = add_uevent_var(env, "MODALIAS=ap:t%02X", ap_dev->device_type);

        return retval;
}

static int ap_dev_suspend(struct device *dev)
{
        struct ap_device *ap_dev = to_ap_dev(dev);

        if (ap_dev->drv && ap_dev->drv->suspend)
                ap_dev->drv->suspend(ap_dev);
        return 0;
}

static int ap_dev_resume(struct device *dev)
{
        struct ap_device *ap_dev = to_ap_dev(dev);

        if (ap_dev->drv && ap_dev->drv->resume)
                ap_dev->drv->resume(ap_dev);
        return 0;
}

static void ap_bus_suspend(void)
{
        AP_DBF(DBF_DEBUG, "ap_bus_suspend running\n");

        ap_suspend_flag = 1;
        /*
         * Disable scanning for devices, thus we do not want to scan
         * for them after removing.
         */
        flush_work(&ap_scan_work);
        tasklet_disable(&ap_tasklet);
}

static int __ap_card_devices_unregister(struct device *dev, void *dummy)
{
        if (is_card_dev(dev))
                device_unregister(dev);
        return 0;
}

static int __ap_queue_devices_unregister(struct device *dev, void *dummy)
{
        if (is_queue_dev(dev))
                device_unregister(dev);
        return 0;
}

static int __ap_queue_devices_with_id_unregister(struct device *dev, void *data)
{
        if (is_queue_dev(dev) &&
            AP_QID_CARD(to_ap_queue(dev)->qid) == (int)(long) data)
                device_unregister(dev);
        return 0;
}

static void ap_bus_resume(void)
{
        int rc;

        AP_DBF(DBF_DEBUG, "ap_bus_resume running\n");

        /* remove all queue devices */
        bus_for_each_dev(&ap_bus_type, NULL, NULL,
                         __ap_queue_devices_unregister);
        /* remove all card devices */
        bus_for_each_dev(&ap_bus_type, NULL, NULL,
                         __ap_card_devices_unregister);

        /* Reset thin interrupt setting */
        if (ap_interrupts_available() && !ap_using_interrupts()) {
                rc = register_adapter_interrupt(&ap_airq);
                ap_airq_flag = (rc == 0);
        }
        if (!ap_interrupts_available() && ap_using_interrupts()) {
                unregister_adapter_interrupt(&ap_airq);
                ap_airq_flag = 0;
        }
        /* Reset domain */
        if (!user_set_domain)
                ap_domain_index = -1;
        /* Get things going again */
        ap_suspend_flag = 0;
        if (ap_airq_flag)
                xchg(ap_airq.lsi_ptr, 0);
        tasklet_enable(&ap_tasklet);
        queue_work(system_long_wq, &ap_scan_work);
}

static int ap_power_event(struct notifier_block *this, unsigned long event,
                          void *ptr)
{
        switch (event) {
        case PM_HIBERNATION_PREPARE:
        case PM_SUSPEND_PREPARE:
                ap_bus_suspend();
                break;
        case PM_POST_HIBERNATION:
        case PM_POST_SUSPEND:
                ap_bus_resume();
                break;
        default:
                break;
        }
        return NOTIFY_DONE;
}
static struct notifier_block ap_power_notifier = {
        .notifier_call = ap_power_event,
};

static SIMPLE_DEV_PM_OPS(ap_bus_pm_ops, ap_dev_suspend, ap_dev_resume);

static struct bus_type ap_bus_type = {
        .name = "ap",
        .match = &ap_bus_match,
        .uevent = &ap_uevent,
        .pm = &ap_bus_pm_ops,
};

static int ap_device_probe(struct device *dev)
{
        struct ap_device *ap_dev = to_ap_dev(dev);
        struct ap_driver *ap_drv = to_ap_drv(dev->driver);
        int rc;

        /* Add queue/card to list of active queues/cards */
        spin_lock_bh(&ap_list_lock);
        if (is_card_dev(dev))
                list_add(&to_ap_card(dev)->list, &ap_card_list);
        else
                list_add(&to_ap_queue(dev)->list,
                         &to_ap_queue(dev)->card->queues);
        spin_unlock_bh(&ap_list_lock);

        ap_dev->drv = ap_drv;
        rc = ap_drv->probe ? ap_drv->probe(ap_dev) : -ENODEV;

        if (rc) {
                spin_lock_bh(&ap_list_lock);
                if (is_card_dev(dev))
                        list_del_init(&to_ap_card(dev)->list);
                else
                        list_del_init(&to_ap_queue(dev)->list);
                spin_unlock_bh(&ap_list_lock);
                ap_dev->drv = NULL;
        }

        return rc;
}

static int ap_device_remove(struct device *dev)
{
        struct ap_device *ap_dev = to_ap_dev(dev);
        struct ap_driver *ap_drv = ap_dev->drv;

        if (ap_drv->remove)
                ap_drv->remove(ap_dev);

        /* Remove queue/card from list of active queues/cards */
        spin_lock_bh(&ap_list_lock);
        if (is_card_dev(dev))
                list_del_init(&to_ap_card(dev)->list);
        else
                list_del_init(&to_ap_queue(dev)->list);
        spin_unlock_bh(&ap_list_lock);

        return 0;
}

int ap_driver_register(struct ap_driver *ap_drv, struct module *owner,
                       char *name)
{
        struct device_driver *drv = &ap_drv->driver;

        if (!initialised)
                return -ENODEV;

        drv->bus = &ap_bus_type;
        drv->probe = ap_device_probe;
        drv->remove = ap_device_remove;
        drv->owner = owner;
        drv->name = name;
        return driver_register(drv);
}
EXPORT_SYMBOL(ap_driver_register);

void ap_driver_unregister(struct ap_driver *ap_drv)
{
        driver_unregister(&ap_drv->driver);
}
EXPORT_SYMBOL(ap_driver_unregister);

void ap_bus_force_rescan(void)
{
        if (ap_suspend_flag)
                return;
        /* processing a asynchronous bus rescan */
        del_timer(&ap_config_timer);
        queue_work(system_long_wq, &ap_scan_work);
        flush_work(&ap_scan_work);
}
EXPORT_SYMBOL(ap_bus_force_rescan);

/*
 * AP bus attributes.
 */
static ssize_t ap_domain_show(struct bus_type *bus, char *buf)
{
        return snprintf(buf, PAGE_SIZE, "%d\n", ap_domain_index);
}

static ssize_t ap_domain_store(struct bus_type *bus,
                               const char *buf, size_t count)
{
        int domain;

        if (sscanf(buf, "%i\n", &domain) != 1 ||
            domain < 0 || domain > ap_max_domain_id)
                return -EINVAL;
        spin_lock_bh(&ap_domain_lock);
        ap_domain_index = domain;
        spin_unlock_bh(&ap_domain_lock);

        AP_DBF(DBF_DEBUG, "stored new default domain=%d\n", domain);

        return count;
}

static BUS_ATTR(ap_domain, 0644, ap_domain_show, ap_domain_store);

static ssize_t ap_control_domain_mask_show(struct bus_type *bus, char *buf)
{
        if (!ap_configuration)  /* QCI not supported */
                return snprintf(buf, PAGE_SIZE, "not supported\n");

        return snprintf(buf, PAGE_SIZE,
                        "0x%08x%08x%08x%08x%08x%08x%08x%08x\n",
                        ap_configuration->adm[0], ap_configuration->adm[1],
                        ap_configuration->adm[2], ap_configuration->adm[3],
                        ap_configuration->adm[4], ap_configuration->adm[5],
                        ap_configuration->adm[6], ap_configuration->adm[7]);
}

static BUS_ATTR(ap_control_domain_mask, 0444,
                ap_control_domain_mask_show, NULL);

static ssize_t ap_usage_domain_mask_show(struct bus_type *bus, char *buf)
{
        if (!ap_configuration)  /* QCI not supported */
                return snprintf(buf, PAGE_SIZE, "not supported\n");

        return snprintf(buf, PAGE_SIZE,
                        "0x%08x%08x%08x%08x%08x%08x%08x%08x\n",
                        ap_configuration->aqm[0], ap_configuration->aqm[1],
                        ap_configuration->aqm[2], ap_configuration->aqm[3],
                        ap_configuration->aqm[4], ap_configuration->aqm[5],
                        ap_configuration->aqm[6], ap_configuration->aqm[7]);
}

static BUS_ATTR(ap_usage_domain_mask, 0444,
                ap_usage_domain_mask_show, NULL);

static ssize_t ap_config_time_show(struct bus_type *bus, char *buf)
{
        return snprintf(buf, PAGE_SIZE, "%d\n", ap_config_time);
}

static ssize_t ap_interrupts_show(struct bus_type *bus, char *buf)
{
        return snprintf(buf, PAGE_SIZE, "%d\n",
                        ap_using_interrupts() ? 1 : 0);
}

static BUS_ATTR(ap_interrupts, 0444, ap_interrupts_show, NULL);

static ssize_t ap_config_time_store(struct bus_type *bus,
                                    const char *buf, size_t count)
{
        int time;

        if (sscanf(buf, "%d\n", &time) != 1 || time < 5 || time > 120)
                return -EINVAL;
        ap_config_time = time;
        mod_timer(&ap_config_timer, jiffies + ap_config_time * HZ);
        return count;
}

static BUS_ATTR(config_time, 0644, ap_config_time_show, ap_config_time_store);

static ssize_t ap_poll_thread_show(struct bus_type *bus, char *buf)
{
        return snprintf(buf, PAGE_SIZE, "%d\n", ap_poll_kthread ? 1 : 0);
}

static ssize_t ap_poll_thread_store(struct bus_type *bus,
                                    const char *buf, size_t count)
{
        int flag, rc;

        if (sscanf(buf, "%d\n", &flag) != 1)
                return -EINVAL;
        if (flag) {
                rc = ap_poll_thread_start();
                if (rc)
                        count = rc;
        } else
                ap_poll_thread_stop();
        return count;
}

static BUS_ATTR(poll_thread, 0644, ap_poll_thread_show, ap_poll_thread_store);

static ssize_t poll_timeout_show(struct bus_type *bus, char *buf)
{
        return snprintf(buf, PAGE_SIZE, "%llu\n", poll_timeout);
}

static ssize_t poll_timeout_store(struct bus_type *bus, const char *buf,
                                  size_t count)
{
        unsigned long long time;
        ktime_t hr_time;

        /* 120 seconds = maximum poll interval */
        if (sscanf(buf, "%llu\n", &time) != 1 || time < 1 ||
            time > 120000000000ULL)
                return -EINVAL;
        poll_timeout = time;
        hr_time = poll_timeout;

        spin_lock_bh(&ap_poll_timer_lock);
        hrtimer_cancel(&ap_poll_timer);
        hrtimer_set_expires(&ap_poll_timer, hr_time);
        hrtimer_start_expires(&ap_poll_timer, HRTIMER_MODE_ABS);
        spin_unlock_bh(&ap_poll_timer_lock);

        return count;
}

static BUS_ATTR(poll_timeout, 0644, poll_timeout_show, poll_timeout_store);

static ssize_t ap_max_domain_id_show(struct bus_type *bus, char *buf)
{
        int max_domain_id;

        if (ap_configuration)
                max_domain_id = ap_max_domain_id ? : -1;
        else
                max_domain_id = 15;
        return snprintf(buf, PAGE_SIZE, "%d\n", max_domain_id);
}

static BUS_ATTR(ap_max_domain_id, 0444, ap_max_domain_id_show, NULL);

static struct bus_attribute *const ap_bus_attrs[] = {
        &bus_attr_ap_domain,
        &bus_attr_ap_control_domain_mask,
        &bus_attr_ap_usage_domain_mask,
        &bus_attr_config_time,
        &bus_attr_poll_thread,
        &bus_attr_ap_interrupts,
        &bus_attr_poll_timeout,
        &bus_attr_ap_max_domain_id,
        NULL,
};

/**
 * ap_select_domain(): Select an AP domain.
 *
 * Pick one of the 16 AP domains.
 */
static int ap_select_domain(void)
{
        int count, max_count, best_domain;
        struct ap_queue_status status;
        int i, j;

        /*
         * We want to use a single domain. Either the one specified with
         * the "domain=" parameter or the domain with the maximum number
         * of devices.
         */
        spin_lock_bh(&ap_domain_lock);
        if (ap_domain_index >= 0) {
                /* Domain has already been selected. */
                spin_unlock_bh(&ap_domain_lock);
                return 0;
        }
        best_domain = -1;
        max_count = 0;
        for (i = 0; i < AP_DOMAINS; i++) {
                if (!ap_test_config_domain(i))
                        continue;
                count = 0;
                for (j = 0; j < AP_DEVICES; j++) {
                        if (!ap_test_config_card_id(j))
                                continue;
                        status = ap_test_queue(AP_MKQID(j, i),
                                               ap_apft_available(),
                                               NULL);
                        if (status.response_code != AP_RESPONSE_NORMAL)
                                continue;
                        count++;
                }
                if (count > max_count) {
                        max_count = count;
                        best_domain = i;
                }
        }
        if (best_domain >= 0){
                ap_domain_index = best_domain;
                AP_DBF(DBF_DEBUG, "new ap_domain_index=%d\n", ap_domain_index);
                spin_unlock_bh(&ap_domain_lock);
                return 0;
        }
        spin_unlock_bh(&ap_domain_lock);
        return -ENODEV;
}

/*
 * This function checks the type and returns either 0 for not
 * supported or the highest compatible type value (which may
 * include the input type value).
 */
static int ap_get_compatible_type(ap_qid_t qid, int rawtype, unsigned int func)
{
        int comp_type = 0;

        /* < CEX2A is not supported */
        if (rawtype < AP_DEVICE_TYPE_CEX2A)
                return 0;

        /* up to CEX6 known and fully supported */
        if (rawtype <= AP_DEVICE_TYPE_CEX6)
                return rawtype;
        /*
         * unknown new type > CEX6, check for compatibility
         * to the highest known and supported type which is
         * currently CEX6 with the help of the QACT function.
         */
        if (ap_qact_available()) {
                struct ap_queue_status status;
                union ap_qact_ap_info apinfo = {0};

                apinfo.mode = (func >> 26) & 0x07;
                apinfo.cat = AP_DEVICE_TYPE_CEX6;
                status = ap_qact(qid, 0, &apinfo);
                if (status.response_code == AP_RESPONSE_NORMAL
                    && apinfo.cat >= AP_DEVICE_TYPE_CEX2A
                    && apinfo.cat <= AP_DEVICE_TYPE_CEX6)
                        comp_type = apinfo.cat;
        }
        if (!comp_type)
                AP_DBF(DBF_WARN, "queue=%02x.%04x unable to map type %d\n",
                       AP_QID_CARD(qid), AP_QID_QUEUE(qid), rawtype);
        else if (comp_type != rawtype)
                AP_DBF(DBF_INFO, "queue=%02x.%04x map type %d to %d\n",
                       AP_QID_CARD(qid), AP_QID_QUEUE(qid), rawtype, comp_type);
        return comp_type;
}

/*
 * helper function to be used with bus_find_dev
 * matches for the card device with the given id
 */
static int __match_card_device_with_id(struct device *dev, void *data)
{
        return is_card_dev(dev) && to_ap_card(dev)->id == (int)(long) data;
}

/* helper function to be used with bus_find_dev
 * matches for the queue device with a given qid
 */
static int __match_queue_device_with_qid(struct device *dev, void *data)
{
        return is_queue_dev(dev) && to_ap_queue(dev)->qid == (int)(long) data;
}

/**
 * ap_scan_bus(): Scan the AP bus for new devices
 * Runs periodically, workqueue timer (ap_config_time)
 */
static void ap_scan_bus(struct work_struct *unused)
{
        struct ap_queue *aq;
        struct ap_card *ac;
        struct device *dev;
        ap_qid_t qid;
        int comp_type, depth = 0, type = 0;
        unsigned int func = 0;
        int rc, id, dom, borked, domains, defdomdevs = 0;

        AP_DBF(DBF_DEBUG, "ap_scan_bus running\n");

        ap_query_configuration(ap_configuration);
        if (ap_select_domain() != 0)
                goto out;

        for (id = 0; id < AP_DEVICES; id++) {
                /* check if device is registered */
                dev = bus_find_device(&ap_bus_type, NULL,
                                      (void *)(long) id,
                                      __match_card_device_with_id);
                ac = dev ? to_ap_card(dev) : NULL;
                if (!ap_test_config_card_id(id)) {
                        if (dev) {
                                /* Card device has been removed from
                                 * configuration, remove the belonging
                                 * queue devices.
                                 */
                                bus_for_each_dev(&ap_bus_type, NULL,
                                        (void *)(long) id,
                                        __ap_queue_devices_with_id_unregister);
                                /* now remove the card device */
                                device_unregister(dev);
                                put_device(dev);
                        }
                        continue;
                }
                /* According to the configuration there should be a card
                 * device, so check if there is at least one valid queue
                 * and maybe create queue devices and the card device.
                 */
                domains = 0;
                for (dom = 0; dom < AP_DOMAINS; dom++) {
                        qid = AP_MKQID(id, dom);
                        dev = bus_find_device(&ap_bus_type, NULL,
                                              (void *)(long) qid,
                                              __match_queue_device_with_qid);
                        aq = dev ? to_ap_queue(dev) : NULL;
                        if (!ap_test_config_domain(dom)) {
                                if (dev) {
                                        /* Queue device exists but has been
                                         * removed from configuration.
                                         */
                                        device_unregister(dev);
                                        put_device(dev);
                                }
                                continue;
                        }
                        rc = ap_query_queue(qid, &depth, &type, &func);
                        if (dev) {
                                spin_lock_bh(&aq->lock);
                                if (rc == -ENODEV ||
                                    /* adapter reconfiguration */
                                    (ac && ac->functions != func))
                                        aq->state = AP_STATE_BORKED;
                                borked = aq->state == AP_STATE_BORKED;
                                spin_unlock_bh(&aq->lock);
                                if (borked)     /* Remove broken device */
                                        device_unregister(dev);
                                put_device(dev);
                                if (!borked) {
                                        domains++;
                                        if (dom == ap_domain_index)
                                                defdomdevs++;
                                        continue;
                                }
                        }
                        if (rc)
                                continue;
                        /* a new queue device is needed, check out comp type */
                        comp_type = ap_get_compatible_type(qid, type, func);
                        if (!comp_type)
                                continue;
                        /* maybe a card device needs to be created first */
                        if (!ac) {
                                ac = ap_card_create(id, depth, type,
                                                    comp_type, func);
                                if (!ac)
                                        continue;
                                ac->ap_dev.device.bus = &ap_bus_type;
                                ac->ap_dev.device.parent = ap_root_device;
                                dev_set_name(&ac->ap_dev.device,
                                             "card%02x", id);
                                /* Register card with AP bus */
                                rc = device_register(&ac->ap_dev.device);
                                if (rc) {
                                        put_device(&ac->ap_dev.device);
                                        ac = NULL;
                                        break;
                                }
                                /* get it and thus adjust reference counter */
                                get_device(&ac->ap_dev.device);
                        }
                        /* now create the new queue device */
                        aq = ap_queue_create(qid, comp_type);
                        if (!aq)
                                continue;
                        aq->card = ac;
                        aq->ap_dev.device.bus = &ap_bus_type;
                        aq->ap_dev.device.parent = &ac->ap_dev.device;
                        dev_set_name(&aq->ap_dev.device,
                                     "%02x.%04x", id, dom);
                        /* Start with a device reset */
                        spin_lock_bh(&aq->lock);
                        ap_wait(ap_sm_event(aq, AP_EVENT_POLL));
                        spin_unlock_bh(&aq->lock);
                        /* Register device */
                        rc = device_register(&aq->ap_dev.device);
                        if (rc) {
                                put_device(&aq->ap_dev.device);
                                continue;
                        }
                        domains++;
                        if (dom == ap_domain_index)
                                defdomdevs++;
                } /* end domain loop */
                if (ac) {
                        /* remove card dev if there are no queue devices */
                        if (!domains)
                                device_unregister(&ac->ap_dev.device);
                        put_device(&ac->ap_dev.device);
                }
        } /* end device loop */

        if (defdomdevs < 1)
                AP_DBF(DBF_INFO, "no queue device with default domain %d available\n",
                       ap_domain_index);

out:
        mod_timer(&ap_config_timer, jiffies + ap_config_time * HZ);
}

static void ap_config_timeout(struct timer_list *unused)
{
        if (ap_suspend_flag)
                return;
        queue_work(system_long_wq, &ap_scan_work);
}

static void ap_reset_all(void)
{
        int i, j;

        for (i = 0; i < AP_DOMAINS; i++) {
                if (!ap_test_config_domain(i))
                        continue;
                for (j = 0; j < AP_DEVICES; j++) {
                        if (!ap_test_config_card_id(j))
                                continue;
                        ap_rapq(AP_MKQID(j, i));
                }
        }
}

static struct reset_call ap_reset_call = {
        .fn = ap_reset_all,
};

int __init ap_debug_init(void)
{
        ap_dbf_info = debug_register("ap", 1, 1,
                                     DBF_MAX_SPRINTF_ARGS * sizeof(long));
        debug_register_view(ap_dbf_info, &debug_sprintf_view);
        debug_set_level(ap_dbf_info, DBF_ERR);

        return 0;
}

void ap_debug_exit(void)
{
        debug_unregister(ap_dbf_info);
}

/**
 * ap_module_init(): The module initialization code.
 *
 * Initializes the module.
 */
int __init ap_module_init(void)
{
        int max_domain_id;
        int rc, i;

        rc = ap_debug_init();
        if (rc)
                return rc;

        if (ap_instructions_available() != 0) {
                pr_warn("The hardware system does not support AP instructions\n");
                return -ENODEV;
        }

        /* Get AP configuration data if available */
        ap_init_configuration();

        if (ap_configuration)
                max_domain_id =
                        ap_max_domain_id ? ap_max_domain_id : AP_DOMAINS - 1;
        else
                max_domain_id = 15;
        if (ap_domain_index < -1 || ap_domain_index > max_domain_id) {
                pr_warn("%d is not a valid cryptographic domain\n",
                        ap_domain_index);
                ap_domain_index = -1;
        }
        /* In resume callback we need to know if the user had set the domain.
         * If so, we can not just reset it.
         */
        if (ap_domain_index >= 0)
                user_set_domain = 1;

        if (ap_interrupts_available()) {
                rc = register_adapter_interrupt(&ap_airq);
                ap_airq_flag = (rc == 0);
        }

        register_reset_call(&ap_reset_call);

        /* Create /sys/bus/ap. */
        rc = bus_register(&ap_bus_type);
        if (rc)
                goto out;
        for (i = 0; ap_bus_attrs[i]; i++) {
                rc = bus_create_file(&ap_bus_type, ap_bus_attrs[i]);
                if (rc)
                        goto out_bus;
        }

        /* Create /sys/devices/ap. */
        ap_root_device = root_device_register("ap");
        rc = PTR_RET(ap_root_device);
        if (rc)
                goto out_bus;

        /* Setup the AP bus rescan timer. */
        timer_setup(&ap_config_timer, ap_config_timeout, 0);

        /*
         * Setup the high resultion poll timer.
         * If we are running under z/VM adjust polling to z/VM polling rate.
         */
        if (MACHINE_IS_VM)
                poll_timeout = 1500000;
        spin_lock_init(&ap_poll_timer_lock);
        hrtimer_init(&ap_poll_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
        ap_poll_timer.function = ap_poll_timeout;

        /* Start the low priority AP bus poll thread. */
        if (ap_thread_flag) {
                rc = ap_poll_thread_start();
                if (rc)
                        goto out_work;
        }

        rc = register_pm_notifier(&ap_power_notifier);
        if (rc)
                goto out_pm;

        queue_work(system_long_wq, &ap_scan_work);
        initialised = true;

        return 0;

out_pm:
        ap_poll_thread_stop();
out_work:
        hrtimer_cancel(&ap_poll_timer);
        root_device_unregister(ap_root_device);
out_bus:
        while (i--)
                bus_remove_file(&ap_bus_type, ap_bus_attrs[i]);
        bus_unregister(&ap_bus_type);
out:
        unregister_reset_call(&ap_reset_call);
        if (ap_using_interrupts())
                unregister_adapter_interrupt(&ap_airq);
        kfree(ap_configuration);
        return rc;
}
device_initcall(ap_module_init);