// SPDX-License-Identifier: GPL-2.0
/*
 * Serial Attached SCSI (SAS) Discover process
 *
 * Copyright (C) 2005 Adaptec, Inc.  All rights reserved.
 * Copyright (C) 2005 Luben Tuikov <luben_tuikov@adaptec.com>
 */

#include <linux/scatterlist.h>
#include <linux/slab.h>
#include <linux/async.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_eh.h>
#include "sas_internal.h"

#include <scsi/scsi_transport.h>
#include <scsi/scsi_transport_sas.h>
#include <scsi/sas_ata.h>
#include "scsi_sas_internal.h"

/* ---------- Basic task processing for discovery purposes ---------- */

void sas_init_dev(struct domain_device *dev)
{
        switch (dev->dev_type) {
        case SAS_END_DEVICE:
                INIT_LIST_HEAD(&dev->ssp_dev.eh_list_node);
                break;
        case SAS_EDGE_EXPANDER_DEVICE:
        case SAS_FANOUT_EXPANDER_DEVICE:
                INIT_LIST_HEAD(&dev->ex_dev.children);
                mutex_init(&dev->ex_dev.cmd_mutex);
                break;
        default:
                break;
        }
}

/* ---------- Domain device discovery ---------- */

/**
 * sas_get_port_device - Discover devices which caused port creation
 * @port: pointer to struct sas_port of interest
 *
 * Devices directly attached to a HA port, have no parent.  This is
 * how we know they are (domain) "root" devices.  All other devices
 * do, and should have their "parent" pointer set appropriately as
 * soon as a child device is discovered.
 */
static int sas_get_port_device(struct asd_sas_port *port)
{
        struct asd_sas_phy *phy;
        struct sas_rphy *rphy;
        struct domain_device *dev;
        int rc = -ENODEV;

        dev = sas_alloc_device();
        if (!dev)
                return -ENOMEM;

        spin_lock_irq(&port->phy_list_lock);
        if (list_empty(&port->phy_list)) {
                spin_unlock_irq(&port->phy_list_lock);
                sas_put_device(dev);
                return -ENODEV;
        }
        phy = container_of(port->phy_list.next, struct asd_sas_phy, port_phy_el);
        spin_lock(&phy->frame_rcvd_lock);
        memcpy(dev->frame_rcvd, phy->frame_rcvd, min(sizeof(dev->frame_rcvd),
                                             (size_t)phy->frame_rcvd_size));
        spin_unlock(&phy->frame_rcvd_lock);
        spin_unlock_irq(&port->phy_list_lock);

        if (dev->frame_rcvd[0] == 0x34 && port->oob_mode == SATA_OOB_MODE) {
                struct dev_to_host_fis *fis =
                        (struct dev_to_host_fis *) dev->frame_rcvd;
                if (fis->interrupt_reason == 1 && fis->lbal == 1 &&
                    fis->byte_count_low == 0x69 && fis->byte_count_high == 0x96
                    && (fis->device & ~0x10) == 0)
                        dev->dev_type = SAS_SATA_PM;
                else
                        dev->dev_type = SAS_SATA_DEV;
                dev->tproto = SAS_PROTOCOL_SATA;
        } else if (port->oob_mode == SAS_OOB_MODE) {
                struct sas_identify_frame *id =
                        (struct sas_identify_frame *) dev->frame_rcvd;
                dev->dev_type = id->dev_type;
                dev->iproto = id->initiator_bits;
                dev->tproto = id->target_bits;
        } else {
                /* If the oob mode is OOB_NOT_CONNECTED, the port is
                 * disconnected due to race with PHY down. We cannot
                 * continue to discover this port
                 */
                sas_put_device(dev);
                pr_warn("Port %016llx is disconnected when discovering\n",
                        SAS_ADDR(port->attached_sas_addr));
                return -ENODEV;
        }

        sas_init_dev(dev);

        dev->port = port;
        switch (dev->dev_type) {
        case SAS_SATA_DEV:
                rc = sas_ata_init(dev);
                if (rc) {
                        rphy = NULL;
                        break;
                }
                fallthrough;
        case SAS_END_DEVICE:
                rphy = sas_end_device_alloc(port->port);
                break;
        case SAS_EDGE_EXPANDER_DEVICE:
                rphy = sas_expander_alloc(port->port,
                                          SAS_EDGE_EXPANDER_DEVICE);
                break;
        case SAS_FANOUT_EXPANDER_DEVICE:
                rphy = sas_expander_alloc(port->port,
                                          SAS_FANOUT_EXPANDER_DEVICE);
                break;
        default:
                pr_warn("ERROR: Unidentified device type %d\n", dev->dev_type);
                rphy = NULL;
                break;
        }

        if (!rphy) {
                sas_put_device(dev);
                return rc;
        }

        rphy->identify.phy_identifier = phy->phy->identify.phy_identifier;
        memcpy(dev->sas_addr, port->attached_sas_addr, SAS_ADDR_SIZE);
        sas_fill_in_rphy(dev, rphy);
        sas_hash_addr(dev->hashed_sas_addr, dev->sas_addr);
        port->port_dev = dev;
        dev->linkrate = port->linkrate;
        dev->min_linkrate = port->linkrate;
        dev->max_linkrate = port->linkrate;
        dev->pathways = port->num_phys;
        memset(port->disc.fanout_sas_addr, 0, SAS_ADDR_SIZE);
        memset(port->disc.eeds_a, 0, SAS_ADDR_SIZE);
        memset(port->disc.eeds_b, 0, SAS_ADDR_SIZE);
        port->disc.max_level = 0;
        sas_device_set_phy(dev, port->port);

        dev->rphy = rphy;
        get_device(&dev->rphy->dev);

        if (dev_is_sata(dev) || dev->dev_type == SAS_END_DEVICE)
                list_add_tail(&dev->disco_list_node, &port->disco_list);
        else {
                spin_lock_irq(&port->dev_list_lock);
                list_add_tail(&dev->dev_list_node, &port->dev_list);
                spin_unlock_irq(&port->dev_list_lock);
        }

        spin_lock_irq(&port->phy_list_lock);
        list_for_each_entry(phy, &port->phy_list, port_phy_el)
                sas_phy_set_target(phy, dev);
        spin_unlock_irq(&port->phy_list_lock);

        return 0;
}

/* ---------- Discover and Revalidate ---------- */

int sas_notify_lldd_dev_found(struct domain_device *dev)
{
        int res = 0;
        struct sas_ha_struct *sas_ha = dev->port->ha;
        struct Scsi_Host *shost = sas_ha->core.shost;
        struct sas_internal *i = to_sas_internal(shost->transportt);

        if (!i->dft->lldd_dev_found)
                return 0;

        res = i->dft->lldd_dev_found(dev);
        if (res) {
                pr_warn("driver on host %s cannot handle device %016llx, error:%d\n",
                        dev_name(sas_ha->dev),
                        SAS_ADDR(dev->sas_addr), res);
                return res;
        }
        set_bit(SAS_DEV_FOUND, &dev->state);
        kref_get(&dev->kref);
        return 0;
}


void sas_notify_lldd_dev_gone(struct domain_device *dev)
{
        struct sas_ha_struct *sas_ha = dev->port->ha;
        struct Scsi_Host *shost = sas_ha->core.shost;
        struct sas_internal *i = to_sas_internal(shost->transportt);

        if (!i->dft->lldd_dev_gone)
                return;

        if (test_and_clear_bit(SAS_DEV_FOUND, &dev->state)) {
                i->dft->lldd_dev_gone(dev);
                sas_put_device(dev);
        }
}

static void sas_probe_devices(struct asd_sas_port *port)
{
        struct domain_device *dev, *n;

        /* devices must be domain members before link recovery and probe */
        list_for_each_entry(dev, &port->disco_list, disco_list_node) {
                spin_lock_irq(&port->dev_list_lock);
                list_add_tail(&dev->dev_list_node, &port->dev_list);
                spin_unlock_irq(&port->dev_list_lock);
        }

        sas_probe_sata(port);

        list_for_each_entry_safe(dev, n, &port->disco_list, disco_list_node) {
                int err;

                err = sas_rphy_add(dev->rphy);
                if (err)
                        sas_fail_probe(dev, __func__, err);
                else
                        list_del_init(&dev->disco_list_node);
        }
}

static void sas_suspend_devices(struct work_struct *work)
{
        struct asd_sas_phy *phy;
        struct domain_device *dev;
        struct sas_discovery_event *ev = to_sas_discovery_event(work);
        struct asd_sas_port *port = ev->port;
        struct Scsi_Host *shost = port->ha->core.shost;
        struct sas_internal *si = to_sas_internal(shost->transportt);

        clear_bit(DISCE_SUSPEND, &port->disc.pending);

        sas_suspend_sata(port);

        /* lldd is free to forget the domain_device across the
         * suspension, we force the issue here to keep the reference
         * counts aligned
         */
        list_for_each_entry(dev, &port->dev_list, dev_list_node)
                sas_notify_lldd_dev_gone(dev);

        /* we are suspending, so we know events are disabled and
         * phy_list is not being mutated
         */
        list_for_each_entry(phy, &port->phy_list, port_phy_el) {
                if (si->dft->lldd_port_deformed)
                        si->dft->lldd_port_deformed(phy);
                phy->suspended = 1;
                port->suspended = 1;
        }
}

static void sas_resume_devices(struct work_struct *work)
{
        struct sas_discovery_event *ev = to_sas_discovery_event(work);
        struct asd_sas_port *port = ev->port;

        clear_bit(DISCE_RESUME, &port->disc.pending);

        sas_resume_sata(port);
}

/**
 * sas_discover_end_dev - discover an end device (SSP, etc)
 * @dev: pointer to domain device of interest
 *
 * See comment in sas_discover_sata().
 */
int sas_discover_end_dev(struct domain_device *dev)
{
        return sas_notify_lldd_dev_found(dev);
}

/* ---------- Device registration and unregistration ---------- */

void sas_free_device(struct kref *kref)
{
        struct domain_device *dev = container_of(kref, typeof(*dev), kref);

        put_device(&dev->rphy->dev);
        dev->rphy = NULL;

        if (dev->parent)
                sas_put_device(dev->parent);

        sas_port_put_phy(dev->phy);
        dev->phy = NULL;

        /* remove the phys and ports, everything else should be gone */
        if (dev_is_expander(dev->dev_type))
                kfree(dev->ex_dev.ex_phy);

        if (dev_is_sata(dev) && dev->sata_dev.ap) {
                ata_sas_tport_delete(dev->sata_dev.ap);
                ata_sas_port_destroy(dev->sata_dev.ap);
                ata_host_put(dev->sata_dev.ata_host);
                dev->sata_dev.ata_host = NULL;
                dev->sata_dev.ap = NULL;
        }

        kfree(dev);
}

static void sas_unregister_common_dev(struct asd_sas_port *port, struct domain_device *dev)
{
        struct sas_ha_struct *ha = port->ha;

        sas_notify_lldd_dev_gone(dev);
        if (!dev->parent)
                dev->port->port_dev = NULL;
        else
                list_del_init(&dev->siblings);

        spin_lock_irq(&port->dev_list_lock);
        list_del_init(&dev->dev_list_node);
        if (dev_is_sata(dev))
                sas_ata_end_eh(dev->sata_dev.ap);
        spin_unlock_irq(&port->dev_list_lock);

        spin_lock_irq(&ha->lock);
        if (dev->dev_type == SAS_END_DEVICE &&
            !list_empty(&dev->ssp_dev.eh_list_node)) {
                list_del_init(&dev->ssp_dev.eh_list_node);
                ha->eh_active--;
        }
        spin_unlock_irq(&ha->lock);

        sas_put_device(dev);
}

void sas_destruct_devices(struct asd_sas_port *port)
{
        struct domain_device *dev, *n;

        list_for_each_entry_safe(dev, n, &port->destroy_list, disco_list_node) {
                list_del_init(&dev->disco_list_node);

                sas_remove_children(&dev->rphy->dev);
                sas_rphy_delete(dev->rphy);
                sas_unregister_common_dev(port, dev);
        }
}

static void sas_destruct_ports(struct asd_sas_port *port)
{
        struct sas_port *sas_port, *p;

        list_for_each_entry_safe(sas_port, p, &port->sas_port_del_list, del_list) {
                list_del_init(&sas_port->del_list);
                sas_port_delete(sas_port);
        }
}

void sas_unregister_dev(struct asd_sas_port *port, struct domain_device *dev)
{
        if (!test_bit(SAS_DEV_DESTROY, &dev->state) &&
            !list_empty(&dev->disco_list_node)) {
                /* this rphy never saw sas_rphy_add */
                list_del_init(&dev->disco_list_node);
                sas_rphy_free(dev->rphy);
                sas_unregister_common_dev(port, dev);
                return;
        }

        if (!test_and_set_bit(SAS_DEV_DESTROY, &dev->state)) {
                sas_rphy_unlink(dev->rphy);
                list_move_tail(&dev->disco_list_node, &port->destroy_list);
        }
}

void sas_unregister_domain_devices(struct asd_sas_port *port, int gone)
{
        struct domain_device *dev, *n;

        list_for_each_entry_safe_reverse(dev, n, &port->dev_list, dev_list_node) {
                if (gone)
                        set_bit(SAS_DEV_GONE, &dev->state);
                sas_unregister_dev(port, dev);
        }

        list_for_each_entry_safe(dev, n, &port->disco_list, disco_list_node)
                sas_unregister_dev(port, dev);

        port->port->rphy = NULL;

}

void sas_device_set_phy(struct domain_device *dev, struct sas_port *port)
{
        struct sas_ha_struct *ha;
        struct sas_phy *new_phy;

        if (!dev)
                return;

        ha = dev->port->ha;
        new_phy = sas_port_get_phy(port);

        /* pin and record last seen phy */
        spin_lock_irq(&ha->phy_port_lock);
        if (new_phy) {
                sas_port_put_phy(dev->phy);
                dev->phy = new_phy;
        }
        spin_unlock_irq(&ha->phy_port_lock);
}

/* ---------- Discovery and Revalidation ---------- */

/**
 * sas_discover_domain - discover the domain
 * @work: work structure embedded in port domain device.
 *
 * NOTE: this process _must_ quit (return) as soon as any connection
 * errors are encountered.  Connection recovery is done elsewhere.
 * Discover process only interrogates devices in order to discover the
 * domain.
 */
static void sas_discover_domain(struct work_struct *work)
{
        struct domain_device *dev;
        int error = 0;
        struct sas_discovery_event *ev = to_sas_discovery_event(work);
        struct asd_sas_port *port = ev->port;

        clear_bit(DISCE_DISCOVER_DOMAIN, &port->disc.pending);

        if (port->port_dev)
                return;

        error = sas_get_port_device(port);
        if (error)
                return;
        dev = port->port_dev;

        pr_debug("DOING DISCOVERY on port %d, pid:%d\n", port->id,
                 task_pid_nr(current));

        switch (dev->dev_type) {
        case SAS_END_DEVICE:
                error = sas_discover_end_dev(dev);
                break;
        case SAS_EDGE_EXPANDER_DEVICE:
        case SAS_FANOUT_EXPANDER_DEVICE:
                error = sas_discover_root_expander(dev);
                break;
        case SAS_SATA_DEV:
        case SAS_SATA_PM:
#ifdef CONFIG_SCSI_SAS_ATA
                error = sas_discover_sata(dev);
                break;
#else
                pr_notice("ATA device seen but CONFIG_SCSI_SAS_ATA=N so cannot attach\n");
                fallthrough;
#endif
                /* Fall through - only for the #else condition above. */
        default:
                error = -ENXIO;
                pr_err("unhandled device %d\n", dev->dev_type);
                break;
        }

        if (error) {
                sas_rphy_free(dev->rphy);
                list_del_init(&dev->disco_list_node);
                spin_lock_irq(&port->dev_list_lock);
                list_del_init(&dev->dev_list_node);
                spin_unlock_irq(&port->dev_list_lock);

                sas_put_device(dev);
                port->port_dev = NULL;
        }

        sas_probe_devices(port);

        pr_debug("DONE DISCOVERY on port %d, pid:%d, result:%d\n", port->id,
                 task_pid_nr(current), error);
}

static void sas_revalidate_domain(struct work_struct *work)
{
        int res = 0;
        struct sas_discovery_event *ev = to_sas_discovery_event(work);
        struct asd_sas_port *port = ev->port;
        struct sas_ha_struct *ha = port->ha;
        struct domain_device *ddev = port->port_dev;

        /* prevent revalidation from finding sata links in recovery */
        mutex_lock(&ha->disco_mutex);
        if (test_bit(SAS_HA_ATA_EH_ACTIVE, &ha->state)) {
                pr_debug("REVALIDATION DEFERRED on port %d, pid:%d\n",
                         port->id, task_pid_nr(current));
                goto out;
        }

        clear_bit(DISCE_REVALIDATE_DOMAIN, &port->disc.pending);

        pr_debug("REVALIDATING DOMAIN on port %d, pid:%d\n", port->id,
                 task_pid_nr(current));

        if (ddev && dev_is_expander(ddev->dev_type))
                res = sas_ex_revalidate_domain(ddev);

        pr_debug("done REVALIDATING DOMAIN on port %d, pid:%d, res 0x%x\n",
                 port->id, task_pid_nr(current), res);
 out:
        mutex_unlock(&ha->disco_mutex);

        sas_destruct_devices(port);
        sas_destruct_ports(port);
        sas_probe_devices(port);
}

/* ---------- Events ---------- */

static void sas_chain_work(struct sas_ha_struct *ha, struct sas_work *sw)
{
        /* chained work is not subject to SA_HA_DRAINING or
         * SAS_HA_REGISTERED, because it is either submitted in the
         * workqueue, or known to be submitted from a context that is
         * not racing against draining
         */
        queue_work(ha->disco_q, &sw->work);
}

static void sas_chain_event(int event, unsigned long *pending,
                            struct sas_work *sw,
                            struct sas_ha_struct *ha)
{
        if (!test_and_set_bit(event, pending)) {
                unsigned long flags;

                spin_lock_irqsave(&ha->lock, flags);
                sas_chain_work(ha, sw);
                spin_unlock_irqrestore(&ha->lock, flags);
        }
}

int sas_discover_event(struct asd_sas_port *port, enum discover_event ev)
{
        struct sas_discovery *disc;

        if (!port)
                return 0;
        disc = &port->disc;

        BUG_ON(ev >= DISC_NUM_EVENTS);

        sas_chain_event(ev, &disc->pending, &disc->disc_work[ev].work, port->ha);

        return 0;
}

/**
 * sas_init_disc - initialize the discovery struct in the port
 * @disc: port discovery structure
 * @port: pointer to struct port
 *
 * Called when the ports are being initialized.
 */
void sas_init_disc(struct sas_discovery *disc, struct asd_sas_port *port)
{
        int i;

        static const work_func_t sas_event_fns[DISC_NUM_EVENTS] = {
                [DISCE_DISCOVER_DOMAIN] = sas_discover_domain,
                [DISCE_REVALIDATE_DOMAIN] = sas_revalidate_domain,
                [DISCE_SUSPEND] = sas_suspend_devices,
                [DISCE_RESUME] = sas_resume_devices,
        };

        disc->pending = 0;
        for (i = 0; i < DISC_NUM_EVENTS; i++) {
                INIT_SAS_WORK(&disc->disc_work[i].work, sas_event_fns[i]);
                disc->disc_work[i].port = port;
        }
}