/*
 * Serial Attached SCSI (SAS) Transport Layer initialization
 *
 * Copyright (C) 2005 Adaptec, Inc.  All rights reserved.
 * Copyright (C) 2005 Luben Tuikov <luben_tuikov@adaptec.com>
 *
 * This file is licensed under GPLv2.
 *
 * 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/module.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/spinlock.h>
#include <scsi/sas_ata.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_transport.h>
#include <scsi/scsi_transport_sas.h>

#include "sas_internal.h"

#include "../scsi_sas_internal.h"

static struct kmem_cache *sas_task_cache;
static struct kmem_cache *sas_event_cache;

struct sas_task *sas_alloc_task(gfp_t flags)
{
        struct sas_task *task = kmem_cache_zalloc(sas_task_cache, flags);

        if (task) {
                spin_lock_init(&task->task_state_lock);
                task->task_state_flags = SAS_TASK_STATE_PENDING;
        }

        return task;
}
EXPORT_SYMBOL_GPL(sas_alloc_task);

struct sas_task *sas_alloc_slow_task(gfp_t flags)
{
        struct sas_task *task = sas_alloc_task(flags);
        struct sas_task_slow *slow = kmalloc(sizeof(*slow), flags);

        if (!task || !slow) {
                if (task)
                        kmem_cache_free(sas_task_cache, task);
                kfree(slow);
                return NULL;
        }

        task->slow_task = slow;
        slow->task = task;
        timer_setup(&slow->timer, NULL, 0);
        init_completion(&slow->completion);

        return task;
}
EXPORT_SYMBOL_GPL(sas_alloc_slow_task);

void sas_free_task(struct sas_task *task)
{
        if (task) {
                kfree(task->slow_task);
                kmem_cache_free(sas_task_cache, task);
        }
}
EXPORT_SYMBOL_GPL(sas_free_task);

/*------------ SAS addr hash -----------*/
void sas_hash_addr(u8 *hashed, const u8 *sas_addr)
{
        const u32 poly = 0x00DB2777;
        u32     r = 0;
        int     i;

        for (i = 0; i < 8; i++) {
                int b;
                for (b = 7; b >= 0; b--) {
                        r <<= 1;
                        if ((1 << b) & sas_addr[i]) {
                                if (!(r & 0x01000000))
                                        r ^= poly;
                        } else if (r & 0x01000000)
                                r ^= poly;
                }
        }

        hashed[0] = (r >> 16) & 0xFF;
        hashed[1] = (r >> 8) & 0xFF ;
        hashed[2] = r & 0xFF;
}

int sas_register_ha(struct sas_ha_struct *sas_ha)
{
        char name[64];
        int error = 0;

        mutex_init(&sas_ha->disco_mutex);
        spin_lock_init(&sas_ha->phy_port_lock);
        sas_hash_addr(sas_ha->hashed_sas_addr, sas_ha->sas_addr);

        set_bit(SAS_HA_REGISTERED, &sas_ha->state);
        spin_lock_init(&sas_ha->lock);
        mutex_init(&sas_ha->drain_mutex);
        init_waitqueue_head(&sas_ha->eh_wait_q);
        INIT_LIST_HEAD(&sas_ha->defer_q);
        INIT_LIST_HEAD(&sas_ha->eh_dev_q);

        sas_ha->event_thres = SAS_PHY_SHUTDOWN_THRES;

        error = sas_register_phys(sas_ha);
        if (error) {
                printk(KERN_NOTICE "couldn't register sas phys:%d\n", error);
                return error;
        }

        error = sas_register_ports(sas_ha);
        if (error) {
                printk(KERN_NOTICE "couldn't register sas ports:%d\n", error);
                goto Undo_phys;
        }

        error = sas_init_events(sas_ha);
        if (error) {
                printk(KERN_NOTICE "couldn't start event thread:%d\n", error);
                goto Undo_ports;
        }

        error = -ENOMEM;
        snprintf(name, sizeof(name), "%s_event_q", dev_name(sas_ha->dev));
        sas_ha->event_q = create_singlethread_workqueue(name);
        if (!sas_ha->event_q)
                goto Undo_ports;

        snprintf(name, sizeof(name), "%s_disco_q", dev_name(sas_ha->dev));
        sas_ha->disco_q = create_singlethread_workqueue(name);
        if (!sas_ha->disco_q)
                goto Undo_event_q;

        INIT_LIST_HEAD(&sas_ha->eh_done_q);
        INIT_LIST_HEAD(&sas_ha->eh_ata_q);

        return 0;

Undo_event_q:
        destroy_workqueue(sas_ha->event_q);
Undo_ports:
        sas_unregister_ports(sas_ha);
Undo_phys:

        return error;
}

static void sas_disable_events(struct sas_ha_struct *sas_ha)
{
        /* Set the state to unregistered to avoid further unchained
         * events to be queued, and flush any in-progress drainers
         */
        mutex_lock(&sas_ha->drain_mutex);
        spin_lock_irq(&sas_ha->lock);
        clear_bit(SAS_HA_REGISTERED, &sas_ha->state);
        spin_unlock_irq(&sas_ha->lock);
        __sas_drain_work(sas_ha);
        mutex_unlock(&sas_ha->drain_mutex);
}

int sas_unregister_ha(struct sas_ha_struct *sas_ha)
{
        sas_disable_events(sas_ha);
        sas_unregister_ports(sas_ha);

        /* flush unregistration work */
        mutex_lock(&sas_ha->drain_mutex);
        __sas_drain_work(sas_ha);
        mutex_unlock(&sas_ha->drain_mutex);

        destroy_workqueue(sas_ha->disco_q);
        destroy_workqueue(sas_ha->event_q);

        return 0;
}

static int sas_get_linkerrors(struct sas_phy *phy)
{
        if (scsi_is_sas_phy_local(phy)) {
                struct Scsi_Host *shost = dev_to_shost(phy->dev.parent);
                struct sas_ha_struct *sas_ha = SHOST_TO_SAS_HA(shost);
                struct asd_sas_phy *asd_phy = sas_ha->sas_phy[phy->number];
                struct sas_internal *i =
                        to_sas_internal(sas_ha->core.shost->transportt);

                return i->dft->lldd_control_phy(asd_phy, PHY_FUNC_GET_EVENTS, NULL);
        }

        return sas_smp_get_phy_events(phy);
}

int sas_try_ata_reset(struct asd_sas_phy *asd_phy)
{
        struct domain_device *dev = NULL;

        /* try to route user requested link resets through libata */
        if (asd_phy->port)
                dev = asd_phy->port->port_dev;

        /* validate that dev has been probed */
        if (dev)
                dev = sas_find_dev_by_rphy(dev->rphy);

        if (dev && dev_is_sata(dev)) {
                sas_ata_schedule_reset(dev);
                sas_ata_wait_eh(dev);
                return 0;
        }

        return -ENODEV;
}

/*
 * transport_sas_phy_reset - reset a phy and permit libata to manage the link
 *
 * phy reset request via sysfs in host workqueue context so we know we
 * can block on eh and safely traverse the domain_device topology
 */
static int transport_sas_phy_reset(struct sas_phy *phy, int hard_reset)
{
        enum phy_func reset_type;

        if (hard_reset)
                reset_type = PHY_FUNC_HARD_RESET;
        else
                reset_type = PHY_FUNC_LINK_RESET;

        if (scsi_is_sas_phy_local(phy)) {
                struct Scsi_Host *shost = dev_to_shost(phy->dev.parent);
                struct sas_ha_struct *sas_ha = SHOST_TO_SAS_HA(shost);
                struct asd_sas_phy *asd_phy = sas_ha->sas_phy[phy->number];
                struct sas_internal *i =
                        to_sas_internal(sas_ha->core.shost->transportt);

                if (!hard_reset && sas_try_ata_reset(asd_phy) == 0)
                        return 0;
                return i->dft->lldd_control_phy(asd_phy, reset_type, NULL);
        } else {
                struct sas_rphy *rphy = dev_to_rphy(phy->dev.parent);
                struct domain_device *ddev = sas_find_dev_by_rphy(rphy);
                struct domain_device *ata_dev = sas_ex_to_ata(ddev, phy->number);

                if (ata_dev && !hard_reset) {
                        sas_ata_schedule_reset(ata_dev);
                        sas_ata_wait_eh(ata_dev);
                        return 0;
                } else
                        return sas_smp_phy_control(ddev, phy->number, reset_type, NULL);
        }
}

static int sas_phy_enable(struct sas_phy *phy, int enable)
{
        int ret;
        enum phy_func cmd;

        if (enable)
                cmd = PHY_FUNC_LINK_RESET;
        else
                cmd = PHY_FUNC_DISABLE;

        if (scsi_is_sas_phy_local(phy)) {
                struct Scsi_Host *shost = dev_to_shost(phy->dev.parent);
                struct sas_ha_struct *sas_ha = SHOST_TO_SAS_HA(shost);
                struct asd_sas_phy *asd_phy = sas_ha->sas_phy[phy->number];
                struct sas_internal *i =
                        to_sas_internal(sas_ha->core.shost->transportt);

                if (enable)
                        ret = transport_sas_phy_reset(phy, 0);
                else
                        ret = i->dft->lldd_control_phy(asd_phy, cmd, NULL);
        } else {
                struct sas_rphy *rphy = dev_to_rphy(phy->dev.parent);
                struct domain_device *ddev = sas_find_dev_by_rphy(rphy);

                if (enable)
                        ret = transport_sas_phy_reset(phy, 0);
                else
                        ret = sas_smp_phy_control(ddev, phy->number, cmd, NULL);
        }
        return ret;
}

int sas_phy_reset(struct sas_phy *phy, int hard_reset)
{
        int ret;
        enum phy_func reset_type;

        if (!phy->enabled)
                return -ENODEV;

        if (hard_reset)
                reset_type = PHY_FUNC_HARD_RESET;
        else
                reset_type = PHY_FUNC_LINK_RESET;

        if (scsi_is_sas_phy_local(phy)) {
                struct Scsi_Host *shost = dev_to_shost(phy->dev.parent);
                struct sas_ha_struct *sas_ha = SHOST_TO_SAS_HA(shost);
                struct asd_sas_phy *asd_phy = sas_ha->sas_phy[phy->number];
                struct sas_internal *i =
                        to_sas_internal(sas_ha->core.shost->transportt);

                ret = i->dft->lldd_control_phy(asd_phy, reset_type, NULL);
        } else {
                struct sas_rphy *rphy = dev_to_rphy(phy->dev.parent);
                struct domain_device *ddev = sas_find_dev_by_rphy(rphy);
                ret = sas_smp_phy_control(ddev, phy->number, reset_type, NULL);
        }
        return ret;
}

int sas_set_phy_speed(struct sas_phy *phy,
                      struct sas_phy_linkrates *rates)
{
        int ret;

        if ((rates->minimum_linkrate &&
             rates->minimum_linkrate > phy->maximum_linkrate) ||
            (rates->maximum_linkrate &&
             rates->maximum_linkrate < phy->minimum_linkrate))
                return -EINVAL;

        if (rates->minimum_linkrate &&
            rates->minimum_linkrate < phy->minimum_linkrate_hw)
                rates->minimum_linkrate = phy->minimum_linkrate_hw;

        if (rates->maximum_linkrate &&
            rates->maximum_linkrate > phy->maximum_linkrate_hw)
                rates->maximum_linkrate = phy->maximum_linkrate_hw;

        if (scsi_is_sas_phy_local(phy)) {
                struct Scsi_Host *shost = dev_to_shost(phy->dev.parent);
                struct sas_ha_struct *sas_ha = SHOST_TO_SAS_HA(shost);
                struct asd_sas_phy *asd_phy = sas_ha->sas_phy[phy->number];
                struct sas_internal *i =
                        to_sas_internal(sas_ha->core.shost->transportt);

                ret = i->dft->lldd_control_phy(asd_phy, PHY_FUNC_SET_LINK_RATE,
                                               rates);
        } else {
                struct sas_rphy *rphy = dev_to_rphy(phy->dev.parent);
                struct domain_device *ddev = sas_find_dev_by_rphy(rphy);
                ret = sas_smp_phy_control(ddev, phy->number,
                                          PHY_FUNC_LINK_RESET, rates);

        }

        return ret;
}

void sas_prep_resume_ha(struct sas_ha_struct *ha)
{
        int i;

        set_bit(SAS_HA_REGISTERED, &ha->state);

        /* clear out any stale link events/data from the suspension path */
        for (i = 0; i < ha->num_phys; i++) {
                struct asd_sas_phy *phy = ha->sas_phy[i];

                memset(phy->attached_sas_addr, 0, SAS_ADDR_SIZE);
                phy->frame_rcvd_size = 0;
        }
}
EXPORT_SYMBOL(sas_prep_resume_ha);

static int phys_suspended(struct sas_ha_struct *ha)
{
        int i, rc = 0;

        for (i = 0; i < ha->num_phys; i++) {
                struct asd_sas_phy *phy = ha->sas_phy[i];

                if (phy->suspended)
                        rc++;
        }

        return rc;
}

void sas_resume_ha(struct sas_ha_struct *ha)
{
        const unsigned long tmo = msecs_to_jiffies(25000);
        int i;

        /* deform ports on phys that did not resume
         * at this point we may be racing the phy coming back (as posted
         * by the lldd).  So we post the event and once we are in the
         * libsas context check that the phy remains suspended before
         * tearing it down.
         */
        i = phys_suspended(ha);
        if (i)
                dev_info(ha->dev, "waiting up to 25 seconds for %d phy%s to resume\n",
                         i, i > 1 ? "s" : "");
        wait_event_timeout(ha->eh_wait_q, phys_suspended(ha) == 0, tmo);
        for (i = 0; i < ha->num_phys; i++) {
                struct asd_sas_phy *phy = ha->sas_phy[i];

                if (phy->suspended) {
                        dev_warn(&phy->phy->dev, "resume timeout\n");
                        sas_notify_phy_event(phy, PHYE_RESUME_TIMEOUT);
                }
        }

        /* all phys are back up or timed out, turn on i/o so we can
         * flush out disks that did not return
         */
        scsi_unblock_requests(ha->core.shost);
        sas_drain_work(ha);
}
EXPORT_SYMBOL(sas_resume_ha);

void sas_suspend_ha(struct sas_ha_struct *ha)
{
        int i;

        sas_disable_events(ha);
        scsi_block_requests(ha->core.shost);
        for (i = 0; i < ha->num_phys; i++) {
                struct asd_sas_port *port = ha->sas_port[i];

                sas_discover_event(port, DISCE_SUSPEND);
        }

        /* flush suspend events while unregistered */
        mutex_lock(&ha->drain_mutex);
        __sas_drain_work(ha);
        mutex_unlock(&ha->drain_mutex);
}
EXPORT_SYMBOL(sas_suspend_ha);

static void sas_phy_release(struct sas_phy *phy)
{
        kfree(phy->hostdata);
        phy->hostdata = NULL;
}

static void phy_reset_work(struct work_struct *work)
{
        struct sas_phy_data *d = container_of(work, typeof(*d), reset_work.work);

        d->reset_result = transport_sas_phy_reset(d->phy, d->hard_reset);
}

static void phy_enable_work(struct work_struct *work)
{
        struct sas_phy_data *d = container_of(work, typeof(*d), enable_work.work);

        d->enable_result = sas_phy_enable(d->phy, d->enable);
}

static int sas_phy_setup(struct sas_phy *phy)
{
        struct sas_phy_data *d = kzalloc(sizeof(*d), GFP_KERNEL);

        if (!d)
                return -ENOMEM;

        mutex_init(&d->event_lock);
        INIT_SAS_WORK(&d->reset_work, phy_reset_work);
        INIT_SAS_WORK(&d->enable_work, phy_enable_work);
        d->phy = phy;
        phy->hostdata = d;

        return 0;
}

static int queue_phy_reset(struct sas_phy *phy, int hard_reset)
{
        struct Scsi_Host *shost = dev_to_shost(phy->dev.parent);
        struct sas_ha_struct *ha = SHOST_TO_SAS_HA(shost);
        struct sas_phy_data *d = phy->hostdata;
        int rc;

        if (!d)
                return -ENOMEM;

        /* libsas workqueue coordinates ata-eh reset with discovery */
        mutex_lock(&d->event_lock);
        d->reset_result = 0;
        d->hard_reset = hard_reset;

        spin_lock_irq(&ha->lock);
        sas_queue_work(ha, &d->reset_work);
        spin_unlock_irq(&ha->lock);

        rc = sas_drain_work(ha);
        if (rc == 0)
                rc = d->reset_result;
        mutex_unlock(&d->event_lock);

        return rc;
}

static int queue_phy_enable(struct sas_phy *phy, int enable)
{
        struct Scsi_Host *shost = dev_to_shost(phy->dev.parent);
        struct sas_ha_struct *ha = SHOST_TO_SAS_HA(shost);
        struct sas_phy_data *d = phy->hostdata;
        int rc;

        if (!d)
                return -ENOMEM;

        /* libsas workqueue coordinates ata-eh reset with discovery */
        mutex_lock(&d->event_lock);
        d->enable_result = 0;
        d->enable = enable;

        spin_lock_irq(&ha->lock);
        sas_queue_work(ha, &d->enable_work);
        spin_unlock_irq(&ha->lock);

        rc = sas_drain_work(ha);
        if (rc == 0)
                rc = d->enable_result;
        mutex_unlock(&d->event_lock);

        return rc;
}

static struct sas_function_template sft = {
        .phy_enable = queue_phy_enable,
        .phy_reset = queue_phy_reset,
        .phy_setup = sas_phy_setup,
        .phy_release = sas_phy_release,
        .set_phy_speed = sas_set_phy_speed,
        .get_linkerrors = sas_get_linkerrors,
        .smp_handler = sas_smp_handler,
};

static inline ssize_t phy_event_threshold_show(struct device *dev,
                        struct device_attribute *attr, char *buf)
{
        struct Scsi_Host *shost = class_to_shost(dev);
        struct sas_ha_struct *sha = SHOST_TO_SAS_HA(shost);

        return scnprintf(buf, PAGE_SIZE, "%u\n", sha->event_thres);
}

static inline ssize_t phy_event_threshold_store(struct device *dev,
                        struct device_attribute *attr,
                        const char *buf, size_t count)
{
        struct Scsi_Host *shost = class_to_shost(dev);
        struct sas_ha_struct *sha = SHOST_TO_SAS_HA(shost);

        sha->event_thres = simple_strtol(buf, NULL, 10);

        /* threshold cannot be set too small */
        if (sha->event_thres < 32)
                sha->event_thres = 32;

        return count;
}

DEVICE_ATTR(phy_event_threshold,
        S_IRUGO|S_IWUSR,
        phy_event_threshold_show,
        phy_event_threshold_store);
EXPORT_SYMBOL_GPL(dev_attr_phy_event_threshold);

struct scsi_transport_template *
sas_domain_attach_transport(struct sas_domain_function_template *dft)
{
        struct scsi_transport_template *stt = sas_attach_transport(&sft);
        struct sas_internal *i;

        if (!stt)
                return stt;

        i = to_sas_internal(stt);
        i->dft = dft;
        stt->create_work_queue = 1;
        stt->eh_strategy_handler = sas_scsi_recover_host;

        return stt;
}
EXPORT_SYMBOL_GPL(sas_domain_attach_transport);


struct asd_sas_event *sas_alloc_event(struct asd_sas_phy *phy)
{
        struct asd_sas_event *event;
        gfp_t flags = in_interrupt() ? GFP_ATOMIC : GFP_KERNEL;
        struct sas_ha_struct *sas_ha = phy->ha;
        struct sas_internal *i =
                to_sas_internal(sas_ha->core.shost->transportt);

        event = kmem_cache_zalloc(sas_event_cache, flags);
        if (!event)
                return NULL;

        atomic_inc(&phy->event_nr);

        if (atomic_read(&phy->event_nr) > phy->ha->event_thres) {
                if (i->dft->lldd_control_phy) {
                        if (cmpxchg(&phy->in_shutdown, 0, 1) == 0) {
                                sas_printk("The phy%02d bursting events, shut it down.\n",
                                        phy->id);
                                sas_notify_phy_event(phy, PHYE_SHUTDOWN);
                        }
                } else {
                        /* Do not support PHY control, stop allocating events */
                        WARN_ONCE(1, "PHY control not supported.\n");
                        kmem_cache_free(sas_event_cache, event);
                        atomic_dec(&phy->event_nr);
                        event = NULL;
                }
        }

        return event;
}

void sas_free_event(struct asd_sas_event *event)
{
        struct asd_sas_phy *phy = event->phy;

        kmem_cache_free(sas_event_cache, event);
        atomic_dec(&phy->event_nr);
}

/* ---------- SAS Class register/unregister ---------- */

static int __init sas_class_init(void)
{
        sas_task_cache = KMEM_CACHE(sas_task, SLAB_HWCACHE_ALIGN);
        if (!sas_task_cache)
                goto out;

        sas_event_cache = KMEM_CACHE(asd_sas_event, SLAB_HWCACHE_ALIGN);
        if (!sas_event_cache)
                goto free_task_kmem;

        return 0;
free_task_kmem:
        kmem_cache_destroy(sas_task_cache);
out:
        return -ENOMEM;
}

static void __exit sas_class_exit(void)
{
        kmem_cache_destroy(sas_task_cache);
        kmem_cache_destroy(sas_event_cache);
}

MODULE_AUTHOR("Luben Tuikov <luben_tuikov@adaptec.com>");
MODULE_DESCRIPTION("SAS Transport Layer");
MODULE_LICENSE("GPL v2");

module_init(sas_class_init);
module_exit(sas_class_exit);

EXPORT_SYMBOL_GPL(sas_register_ha);
EXPORT_SYMBOL_GPL(sas_unregister_ha);