/*
 *    Copyright IBM Corp. 1999, 2010
 *    Author(s): Cornelia Huck (cornelia.huck@de.ibm.com)
 *               Arnd Bergmann (arndb@de.ibm.com)
 *               Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
 */

#include <linux/bug.h>
#include <linux/workqueue.h>
#include <linux/spinlock.h>
#include <linux/export.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/wait.h>
#include <linux/mutex.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <asm/chpid.h>
#include <asm/sclp.h>
#include <asm/crw.h>

#include "cio.h"
#include "css.h"
#include "ioasm.h"
#include "cio_debug.h"
#include "chp.h"

#define to_channelpath(device) container_of(device, struct channel_path, dev)
#define CHP_INFO_UPDATE_INTERVAL        1*HZ

enum cfg_task_t {
        cfg_none,
        cfg_configure,
        cfg_deconfigure
};

/* Map for pending configure tasks. */
static enum cfg_task_t chp_cfg_task[__MAX_CSSID + 1][__MAX_CHPID + 1];
static DEFINE_SPINLOCK(cfg_lock);

/* Map for channel-path status. */
static struct sclp_chp_info chp_info;
static DEFINE_MUTEX(info_lock);

/* Time after which channel-path status may be outdated. */
static unsigned long chp_info_expires;

static struct work_struct cfg_work;

/* Wait queue for configure completion events. */
static wait_queue_head_t cfg_wait_queue;

/* Set vary state for given chpid. */
static void set_chp_logically_online(struct chp_id chpid, int onoff)
{
        chpid_to_chp(chpid)->state = onoff;
}

/* On success return 0 if channel-path is varied offline, 1 if it is varied
 * online. Return -ENODEV if channel-path is not registered. */
int chp_get_status(struct chp_id chpid)
{
        return (chpid_to_chp(chpid) ? chpid_to_chp(chpid)->state : -ENODEV);
}

/**
 * chp_get_sch_opm - return opm for subchannel
 * @sch: subchannel
 *
 * Calculate and return the operational path mask (opm) based on the chpids
 * used by the subchannel and the status of the associated channel-paths.
 */
u8 chp_get_sch_opm(struct subchannel *sch)
{
        struct chp_id chpid;
        int opm;
        int i;

        opm = 0;
        chp_id_init(&chpid);
        for (i = 0; i < 8; i++) {
                opm <<= 1;
                chpid.id = sch->schib.pmcw.chpid[i];
                if (chp_get_status(chpid) != 0)
                        opm |= 1;
        }
        return opm;
}
EXPORT_SYMBOL_GPL(chp_get_sch_opm);

/**
 * chp_is_registered - check if a channel-path is registered
 * @chpid: channel-path ID
 *
 * Return non-zero if a channel-path with the given chpid is registered,
 * zero otherwise.
 */
int chp_is_registered(struct chp_id chpid)
{
        return chpid_to_chp(chpid) != NULL;
}

/*
 * Function: s390_vary_chpid
 * Varies the specified chpid online or offline
 */
static int s390_vary_chpid(struct chp_id chpid, int on)
{
        char dbf_text[15];
        int status;

        sprintf(dbf_text, on?"varyon%x.%02x":"varyoff%x.%02x", chpid.cssid,
                chpid.id);
        CIO_TRACE_EVENT(2, dbf_text);

        status = chp_get_status(chpid);
        if (!on && !status)
                return 0;

        set_chp_logically_online(chpid, on);
        chsc_chp_vary(chpid, on);
        return 0;
}

/*
 * Channel measurement related functions
 */
static ssize_t chp_measurement_chars_read(struct file *filp,
                                          struct kobject *kobj,
                                          struct bin_attribute *bin_attr,
                                          char *buf, loff_t off, size_t count)
{
        struct channel_path *chp;
        struct device *device;

        device = container_of(kobj, struct device, kobj);
        chp = to_channelpath(device);
        if (chp->cmg == -1)
                return 0;

        return memory_read_from_buffer(buf, count, &off, &chp->cmg_chars,
                                       sizeof(chp->cmg_chars));
}

static const struct bin_attribute chp_measurement_chars_attr = {
        .attr = {
                .name = "measurement_chars",
                .mode = S_IRUSR,
        },
        .size = sizeof(struct cmg_chars),
        .read = chp_measurement_chars_read,
};

static void chp_measurement_copy_block(struct cmg_entry *buf,
                                       struct channel_subsystem *css,
                                       struct chp_id chpid)
{
        void *area;
        struct cmg_entry *entry, reference_buf;
        int idx;

        if (chpid.id < 128) {
                area = css->cub_addr1;
                idx = chpid.id;
        } else {
                area = css->cub_addr2;
                idx = chpid.id - 128;
        }
        entry = area + (idx * sizeof(struct cmg_entry));
        do {
                memcpy(buf, entry, sizeof(*entry));
                memcpy(&reference_buf, entry, sizeof(*entry));
        } while (reference_buf.values[0] != buf->values[0]);
}

static ssize_t chp_measurement_read(struct file *filp, struct kobject *kobj,
                                    struct bin_attribute *bin_attr,
                                    char *buf, loff_t off, size_t count)
{
        struct channel_path *chp;
        struct channel_subsystem *css;
        struct device *device;
        unsigned int size;

        device = container_of(kobj, struct device, kobj);
        chp = to_channelpath(device);
        css = to_css(chp->dev.parent);

        size = sizeof(struct cmg_entry);

        /* Only allow single reads. */
        if (off || count < size)
                return 0;
        chp_measurement_copy_block((struct cmg_entry *)buf, css, chp->chpid);
        count = size;
        return count;
}

static const struct bin_attribute chp_measurement_attr = {
        .attr = {
                .name = "measurement",
                .mode = S_IRUSR,
        },
        .size = sizeof(struct cmg_entry),
        .read = chp_measurement_read,
};

void chp_remove_cmg_attr(struct channel_path *chp)
{
        device_remove_bin_file(&chp->dev, &chp_measurement_chars_attr);
        device_remove_bin_file(&chp->dev, &chp_measurement_attr);
}

int chp_add_cmg_attr(struct channel_path *chp)
{
        int ret;

        ret = device_create_bin_file(&chp->dev, &chp_measurement_chars_attr);
        if (ret)
                return ret;
        ret = device_create_bin_file(&chp->dev, &chp_measurement_attr);
        if (ret)
                device_remove_bin_file(&chp->dev, &chp_measurement_chars_attr);
        return ret;
}

/*
 * Files for the channel path entries.
 */
static ssize_t chp_status_show(struct device *dev,
                               struct device_attribute *attr, char *buf)
{
        struct channel_path *chp = to_channelpath(dev);
        int status;

        mutex_lock(&chp->lock);
        status = chp->state;
        mutex_unlock(&chp->lock);

        return status ? sprintf(buf, "online\n") : sprintf(buf, "offline\n");
}

static ssize_t chp_status_write(struct device *dev,
                                struct device_attribute *attr,
                                const char *buf, size_t count)
{
        struct channel_path *cp = to_channelpath(dev);
        char cmd[10];
        int num_args;
        int error;

        num_args = sscanf(buf, "%5s", cmd);
        if (!num_args)
                return count;

        if (!strncasecmp(cmd, "on", 2) || !strcmp(cmd, "1")) {
                mutex_lock(&cp->lock);
                error = s390_vary_chpid(cp->chpid, 1);
                mutex_unlock(&cp->lock);
        } else if (!strncasecmp(cmd, "off", 3) || !strcmp(cmd, "0")) {
                mutex_lock(&cp->lock);
                error = s390_vary_chpid(cp->chpid, 0);
                mutex_unlock(&cp->lock);
        } else
                error = -EINVAL;

        return error < 0 ? error : count;
}

static DEVICE_ATTR(status, 0644, chp_status_show, chp_status_write);

static ssize_t chp_configure_show(struct device *dev,
                                  struct device_attribute *attr, char *buf)
{
        struct channel_path *cp;
        int status;

        cp = to_channelpath(dev);
        status = chp_info_get_status(cp->chpid);
        if (status < 0)
                return status;

        return snprintf(buf, PAGE_SIZE, "%d\n", status);
}

static int cfg_wait_idle(void);

static ssize_t chp_configure_write(struct device *dev,
                                   struct device_attribute *attr,
                                   const char *buf, size_t count)
{
        struct channel_path *cp;
        int val;
        char delim;

        if (sscanf(buf, "%d %c", &val, &delim) != 1)
                return -EINVAL;
        if (val != 0 && val != 1)
                return -EINVAL;
        cp = to_channelpath(dev);
        chp_cfg_schedule(cp->chpid, val);
        cfg_wait_idle();

        return count;
}

static DEVICE_ATTR(configure, 0644, chp_configure_show, chp_configure_write);

static ssize_t chp_type_show(struct device *dev, struct device_attribute *attr,
                             char *buf)
{
        struct channel_path *chp = to_channelpath(dev);
        u8 type;

        mutex_lock(&chp->lock);
        type = chp->desc.desc;
        mutex_unlock(&chp->lock);
        return sprintf(buf, "%x\n", type);
}

static DEVICE_ATTR(type, 0444, chp_type_show, NULL);

static ssize_t chp_cmg_show(struct device *dev, struct device_attribute *attr,
                            char *buf)
{
        struct channel_path *chp = to_channelpath(dev);

        if (!chp)
                return 0;
        if (chp->cmg == -1) /* channel measurements not available */
                return sprintf(buf, "unknown\n");
        return sprintf(buf, "%x\n", chp->cmg);
}

static DEVICE_ATTR(cmg, 0444, chp_cmg_show, NULL);

static ssize_t chp_shared_show(struct device *dev,
                               struct device_attribute *attr, char *buf)
{
        struct channel_path *chp = to_channelpath(dev);

        if (!chp)
                return 0;
        if (chp->shared == -1) /* channel measurements not available */
                return sprintf(buf, "unknown\n");
        return sprintf(buf, "%x\n", chp->shared);
}

static DEVICE_ATTR(shared, 0444, chp_shared_show, NULL);

static ssize_t chp_chid_show(struct device *dev, struct device_attribute *attr,
                             char *buf)
{
        struct channel_path *chp = to_channelpath(dev);
        ssize_t rc;

        mutex_lock(&chp->lock);
        if (chp->desc_fmt1.flags & 0x10)
                rc = sprintf(buf, "%04x\n", chp->desc_fmt1.chid);
        else
                rc = 0;
        mutex_unlock(&chp->lock);

        return rc;
}
static DEVICE_ATTR(chid, 0444, chp_chid_show, NULL);

static ssize_t chp_chid_external_show(struct device *dev,
                                      struct device_attribute *attr, char *buf)
{
        struct channel_path *chp = to_channelpath(dev);
        ssize_t rc;

        mutex_lock(&chp->lock);
        if (chp->desc_fmt1.flags & 0x10)
                rc = sprintf(buf, "%x\n", chp->desc_fmt1.flags & 0x8 ? 1 : 0);
        else
                rc = 0;
        mutex_unlock(&chp->lock);

        return rc;
}
static DEVICE_ATTR(chid_external, 0444, chp_chid_external_show, NULL);

static struct attribute *chp_attrs[] = {
        &dev_attr_status.attr,
        &dev_attr_configure.attr,
        &dev_attr_type.attr,
        &dev_attr_cmg.attr,
        &dev_attr_shared.attr,
        &dev_attr_chid.attr,
        &dev_attr_chid_external.attr,
        NULL,
};
static struct attribute_group chp_attr_group = {
        .attrs = chp_attrs,
};
static const struct attribute_group *chp_attr_groups[] = {
        &chp_attr_group,
        NULL,
};

static void chp_release(struct device *dev)
{
        struct channel_path *cp;

        cp = to_channelpath(dev);
        kfree(cp);
}

/**
 * chp_update_desc - update channel-path description
 * @chp - channel-path
 *
 * Update the channel-path description of the specified channel-path
 * including channel measurement related information.
 * Return zero on success, non-zero otherwise.
 */
int chp_update_desc(struct channel_path *chp)
{
        int rc;

        rc = chsc_determine_base_channel_path_desc(chp->chpid, &chp->desc);
        if (rc)
                return rc;

        /*
         * Fetching the following data is optional. Not all machines or
         * hypervisors implement the required chsc commands.
         */
        chsc_determine_fmt1_channel_path_desc(chp->chpid, &chp->desc_fmt1);
        chsc_get_channel_measurement_chars(chp);

        return 0;
}

/**
 * chp_new - register a new channel-path
 * @chpid - channel-path ID
 *
 * Create and register data structure representing new channel-path. Return
 * zero on success, non-zero otherwise.
 */
int chp_new(struct chp_id chpid)
{
        struct channel_subsystem *css = css_by_id(chpid.cssid);
        struct channel_path *chp;
        int ret;

        if (chp_is_registered(chpid))
                return 0;
        chp = kzalloc(sizeof(struct channel_path), GFP_KERNEL);
        if (!chp)
                return -ENOMEM;

        /* fill in status, etc. */
        chp->chpid = chpid;
        chp->state = 1;
        chp->dev.parent = &css->device;
        chp->dev.groups = chp_attr_groups;
        chp->dev.release = chp_release;
        mutex_init(&chp->lock);

        /* Obtain channel path description and fill it in. */
        ret = chp_update_desc(chp);
        if (ret)
                goto out_free;
        if ((chp->desc.flags & 0x80) == 0) {
                ret = -ENODEV;
                goto out_free;
        }
        dev_set_name(&chp->dev, "chp%x.%02x", chpid.cssid, chpid.id);

        /* make it known to the system */
        ret = device_register(&chp->dev);
        if (ret) {
                CIO_MSG_EVENT(0, "Could not register chp%x.%02x: %d\n",
                              chpid.cssid, chpid.id, ret);
                put_device(&chp->dev);
                goto out;
        }
        mutex_lock(&css->mutex);
        if (css->cm_enabled) {
                ret = chp_add_cmg_attr(chp);
                if (ret) {
                        device_unregister(&chp->dev);
                        mutex_unlock(&css->mutex);
                        goto out;
                }
        }
        css->chps[chpid.id] = chp;
        mutex_unlock(&css->mutex);
        goto out;
out_free:
        kfree(chp);
out:
        return ret;
}

/**
 * chp_get_chp_desc - return newly allocated channel-path description
 * @chpid: channel-path ID
 *
 * On success return a newly allocated copy of the channel-path description
 * data associated with the given channel-path ID. Return %NULL on error.
 */
struct channel_path_desc *chp_get_chp_desc(struct chp_id chpid)
{
        struct channel_path *chp;
        struct channel_path_desc *desc;

        chp = chpid_to_chp(chpid);
        if (!chp)
                return NULL;
        desc = kmalloc(sizeof(struct channel_path_desc), GFP_KERNEL);
        if (!desc)
                return NULL;

        mutex_lock(&chp->lock);
        memcpy(desc, &chp->desc, sizeof(struct channel_path_desc));
        mutex_unlock(&chp->lock);
        return desc;
}

/**
 * chp_process_crw - process channel-path status change
 * @crw0: channel report-word to handler
 * @crw1: second channel-report word (always NULL)
 * @overflow: crw overflow indication
 *
 * Handle channel-report-words indicating that the status of a channel-path
 * has changed.
 */
static void chp_process_crw(struct crw *crw0, struct crw *crw1,
                            int overflow)
{
        struct chp_id chpid;

        if (overflow) {
                css_schedule_eval_all();
                return;
        }
        CIO_CRW_EVENT(2, "CRW reports slct=%d, oflw=%d, "
                      "chn=%d, rsc=%X, anc=%d, erc=%X, rsid=%X\n",
                      crw0->slct, crw0->oflw, crw0->chn, crw0->rsc, crw0->anc,
                      crw0->erc, crw0->rsid);
        /*
         * Check for solicited machine checks. These are
         * created by reset channel path and need not be
         * handled here.
         */
        if (crw0->slct) {
                CIO_CRW_EVENT(2, "solicited machine check for "
                              "channel path %02X\n", crw0->rsid);
                return;
        }
        chp_id_init(&chpid);
        chpid.id = crw0->rsid;
        switch (crw0->erc) {
        case CRW_ERC_IPARM: /* Path has come. */
        case CRW_ERC_INIT:
                if (!chp_is_registered(chpid))
                        chp_new(chpid);
                chsc_chp_online(chpid);
                break;
        case CRW_ERC_PERRI: /* Path has gone. */
        case CRW_ERC_PERRN:
                chsc_chp_offline(chpid);
                break;
        default:
                CIO_CRW_EVENT(2, "Don't know how to handle erc=%x\n",
                              crw0->erc);
        }
}

int chp_ssd_get_mask(struct chsc_ssd_info *ssd, struct chp_link *link)
{
        int i;
        int mask;

        for (i = 0; i < 8; i++) {
                mask = 0x80 >> i;
                if (!(ssd->path_mask & mask))
                        continue;
                if (!chp_id_is_equal(&ssd->chpid[i], &link->chpid))
                        continue;
                if ((ssd->fla_valid_mask & mask) &&
                    ((ssd->fla[i] & link->fla_mask) != link->fla))
                        continue;
                return mask;
        }
        return 0;
}
EXPORT_SYMBOL_GPL(chp_ssd_get_mask);

static inline int info_bit_num(struct chp_id id)
{
        return id.id + id.cssid * (__MAX_CHPID + 1);
}

/* Force chp_info refresh on next call to info_validate(). */
static void info_expire(void)
{
        mutex_lock(&info_lock);
        chp_info_expires = jiffies - 1;
        mutex_unlock(&info_lock);
}

/* Ensure that chp_info is up-to-date. */
static int info_update(void)
{
        int rc;

        mutex_lock(&info_lock);
        rc = 0;
        if (time_after(jiffies, chp_info_expires)) {
                /* Data is too old, update. */
                rc = sclp_chp_read_info(&chp_info);
                chp_info_expires = jiffies + CHP_INFO_UPDATE_INTERVAL ;
        }
        mutex_unlock(&info_lock);

        return rc;
}

/**
 * chp_info_get_status - retrieve configure status of a channel-path
 * @chpid: channel-path ID
 *
 * On success, return 0 for standby, 1 for configured, 2 for reserved,
 * 3 for not recognized. Return negative error code on error.
 */
int chp_info_get_status(struct chp_id chpid)
{
        int rc;
        int bit;

        rc = info_update();
        if (rc)
                return rc;

        bit = info_bit_num(chpid);
        mutex_lock(&info_lock);
        if (!chp_test_bit(chp_info.recognized, bit))
                rc = CHP_STATUS_NOT_RECOGNIZED;
        else if (chp_test_bit(chp_info.configured, bit))
                rc = CHP_STATUS_CONFIGURED;
        else if (chp_test_bit(chp_info.standby, bit))
                rc = CHP_STATUS_STANDBY;
        else
                rc = CHP_STATUS_RESERVED;
        mutex_unlock(&info_lock);

        return rc;
}

/* Return configure task for chpid. */
static enum cfg_task_t cfg_get_task(struct chp_id chpid)
{
        return chp_cfg_task[chpid.cssid][chpid.id];
}

/* Set configure task for chpid. */
static void cfg_set_task(struct chp_id chpid, enum cfg_task_t cfg)
{
        chp_cfg_task[chpid.cssid][chpid.id] = cfg;
}

/* Fetch the first configure task. Set chpid accordingly. */
static enum cfg_task_t chp_cfg_fetch_task(struct chp_id *chpid)
{
        enum cfg_task_t t = cfg_none;

        chp_id_for_each(chpid) {
                t = cfg_get_task(*chpid);
                if (t != cfg_none)
                        break;
        }

        return t;
}

/* Perform one configure/deconfigure request. Reschedule work function until
 * last request. */
static void cfg_func(struct work_struct *work)
{
        struct chp_id chpid;
        enum cfg_task_t t;
        int rc;

        spin_lock(&cfg_lock);
        t = chp_cfg_fetch_task(&chpid);
        spin_unlock(&cfg_lock);

        switch (t) {
        case cfg_configure:
                rc = sclp_chp_configure(chpid);
                if (rc)
                        CIO_MSG_EVENT(2, "chp: sclp_chp_configure(%x.%02x)="
                                      "%d\n", chpid.cssid, chpid.id, rc);
                else {
                        info_expire();
                        chsc_chp_online(chpid);
                }
                break;
        case cfg_deconfigure:
                rc = sclp_chp_deconfigure(chpid);
                if (rc)
                        CIO_MSG_EVENT(2, "chp: sclp_chp_deconfigure(%x.%02x)="
                                      "%d\n", chpid.cssid, chpid.id, rc);
                else {
                        info_expire();
                        chsc_chp_offline(chpid);
                }
                break;
        case cfg_none:
                /* Get updated information after last change. */
                info_update();
                wake_up_interruptible(&cfg_wait_queue);
                return;
        }
        spin_lock(&cfg_lock);
        if (t == cfg_get_task(chpid))
                cfg_set_task(chpid, cfg_none);
        spin_unlock(&cfg_lock);
        schedule_work(&cfg_work);
}

/**
 * chp_cfg_schedule - schedule chpid configuration request
 * @chpid - channel-path ID
 * @configure - Non-zero for configure, zero for deconfigure
 *
 * Schedule a channel-path configuration/deconfiguration request.
 */
void chp_cfg_schedule(struct chp_id chpid, int configure)
{
        CIO_MSG_EVENT(2, "chp_cfg_sched%x.%02x=%d\n", chpid.cssid, chpid.id,
                      configure);
        spin_lock(&cfg_lock);
        cfg_set_task(chpid, configure ? cfg_configure : cfg_deconfigure);
        spin_unlock(&cfg_lock);
        schedule_work(&cfg_work);
}

/**
 * chp_cfg_cancel_deconfigure - cancel chpid deconfiguration request
 * @chpid - channel-path ID
 *
 * Cancel an active channel-path deconfiguration request if it has not yet
 * been performed.
 */
void chp_cfg_cancel_deconfigure(struct chp_id chpid)
{
        CIO_MSG_EVENT(2, "chp_cfg_cancel:%x.%02x\n", chpid.cssid, chpid.id);
        spin_lock(&cfg_lock);
        if (cfg_get_task(chpid) == cfg_deconfigure)
                cfg_set_task(chpid, cfg_none);
        spin_unlock(&cfg_lock);
}

static bool cfg_idle(void)
{
        struct chp_id chpid;
        enum cfg_task_t t;

        spin_lock(&cfg_lock);
        t = chp_cfg_fetch_task(&chpid);
        spin_unlock(&cfg_lock);

        return t == cfg_none;
}

static int cfg_wait_idle(void)
{
        if (wait_event_interruptible(cfg_wait_queue, cfg_idle()))
                return -ERESTARTSYS;
        return 0;
}

static int __init chp_init(void)
{
        struct chp_id chpid;
        int state, ret;

        ret = crw_register_handler(CRW_RSC_CPATH, chp_process_crw);
        if (ret)
                return ret;
        INIT_WORK(&cfg_work, cfg_func);
        init_waitqueue_head(&cfg_wait_queue);
        if (info_update())
                return 0;
        /* Register available channel-paths. */
        chp_id_for_each(&chpid) {
                state = chp_info_get_status(chpid);
                if (state == CHP_STATUS_CONFIGURED ||
                    state == CHP_STATUS_STANDBY)
                        chp_new(chpid);
        }

        return 0;
}

subsys_initcall(chp_init);