/*
 * usb port device code
 *
 * Copyright (C) 2012 Intel Corp
 *
 * Author: Lan Tianyu <tianyu.lan@intel.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * 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.
 *
 */

#include <linux/slab.h>
#include <linux/pm_qos.h>

#include "hub.h"

static int usb_port_block_power_off;

static const struct attribute_group *port_dev_group[];

static ssize_t connect_type_show(struct device *dev,
                                 struct device_attribute *attr, char *buf)
{
        struct usb_port *port_dev = to_usb_port(dev);
        char *result;

        switch (port_dev->connect_type) {
        case USB_PORT_CONNECT_TYPE_HOT_PLUG:
                result = "hotplug";
                break;
        case USB_PORT_CONNECT_TYPE_HARD_WIRED:
                result = "hardwired";
                break;
        case USB_PORT_NOT_USED:
                result = "not used";
                break;
        default:
                result = "unknown";
                break;
        }

        return sprintf(buf, "%s\n", result);
}
static DEVICE_ATTR_RO(connect_type);

static struct attribute *port_dev_attrs[] = {
        &dev_attr_connect_type.attr,
        NULL,
};

static struct attribute_group port_dev_attr_grp = {
        .attrs = port_dev_attrs,
};

static const struct attribute_group *port_dev_group[] = {
        &port_dev_attr_grp,
        NULL,
};

static void usb_port_device_release(struct device *dev)
{
        struct usb_port *port_dev = to_usb_port(dev);

        kfree(port_dev->req);
        kfree(port_dev);
}

#ifdef CONFIG_PM
static int usb_port_runtime_resume(struct device *dev)
{
        struct usb_port *port_dev = to_usb_port(dev);
        struct usb_device *hdev = to_usb_device(dev->parent->parent);
        struct usb_interface *intf = to_usb_interface(dev->parent);
        struct usb_hub *hub = usb_hub_to_struct_hub(hdev);
        struct usb_device *udev = port_dev->child;
        struct usb_port *peer = port_dev->peer;
        int port1 = port_dev->portnum;
        int retval;

        if (!hub)
                return -EINVAL;
        if (hub->in_reset) {
                set_bit(port1, hub->power_bits);
                return 0;
        }

        /*
         * Power on our usb3 peer before this usb2 port to prevent a usb3
         * device from degrading to its usb2 connection
         */
        if (!port_dev->is_superspeed && peer)
                pm_runtime_get_sync(&peer->dev);

        usb_autopm_get_interface(intf);
        retval = usb_hub_set_port_power(hdev, hub, port1, true);
        msleep(hub_power_on_good_delay(hub));
        if (udev && !retval) {
                /*
                 * Our preference is to simply wait for the port to reconnect,
                 * as that is the lowest latency method to restart the port.
                 * However, there are cases where toggling port power results in
                 * the host port and the device port getting out of sync causing
                 * a link training live lock.  Upon timeout, flag the port as
                 * needing warm reset recovery (to be performed later by
                 * usb_port_resume() as requested via usb_wakeup_notification())
                 */
                if (hub_port_debounce_be_connected(hub, port1) < 0) {
                        dev_dbg(&port_dev->dev, "reconnect timeout\n");
                        if (hub_is_superspeed(hdev))
                                set_bit(port1, hub->warm_reset_bits);
                }

                /* Force the child awake to revalidate after the power loss. */
                if (!test_and_set_bit(port1, hub->child_usage_bits)) {
                        pm_runtime_get_noresume(&port_dev->dev);
                        pm_request_resume(&udev->dev);
                }
        }

        usb_autopm_put_interface(intf);

        return retval;
}

static int usb_port_runtime_suspend(struct device *dev)
{
        struct usb_port *port_dev = to_usb_port(dev);
        struct usb_device *hdev = to_usb_device(dev->parent->parent);
        struct usb_interface *intf = to_usb_interface(dev->parent);
        struct usb_hub *hub = usb_hub_to_struct_hub(hdev);
        struct usb_port *peer = port_dev->peer;
        int port1 = port_dev->portnum;
        int retval;

        if (!hub)
                return -EINVAL;
        if (hub->in_reset)
                return -EBUSY;

        if (dev_pm_qos_flags(&port_dev->dev, PM_QOS_FLAG_NO_POWER_OFF)
                        == PM_QOS_FLAGS_ALL)
                return -EAGAIN;

        if (usb_port_block_power_off)
                return -EBUSY;

        usb_autopm_get_interface(intf);
        retval = usb_hub_set_port_power(hdev, hub, port1, false);
        usb_clear_port_feature(hdev, port1, USB_PORT_FEAT_C_CONNECTION);
        if (!port_dev->is_superspeed)
                usb_clear_port_feature(hdev, port1, USB_PORT_FEAT_C_ENABLE);
        usb_autopm_put_interface(intf);

        /*
         * Our peer usb3 port may now be able to suspend, so
         * asynchronously queue a suspend request to observe that this
         * usb2 port is now off.
         */
        if (!port_dev->is_superspeed && peer)
                pm_runtime_put(&peer->dev);

        return retval;
}
#endif

static const struct dev_pm_ops usb_port_pm_ops = {
#ifdef CONFIG_PM
        .runtime_suspend =      usb_port_runtime_suspend,
        .runtime_resume =       usb_port_runtime_resume,
#endif
};

struct device_type usb_port_device_type = {
        .name =         "usb_port",
        .release =      usb_port_device_release,
        .pm =           &usb_port_pm_ops,
};

static struct device_driver usb_port_driver = {
        .name = "usb",
        .owner = THIS_MODULE,
};

static int link_peers(struct usb_port *left, struct usb_port *right)
{
        struct usb_port *ss_port, *hs_port;
        int rc;

        if (left->peer == right && right->peer == left)
                return 0;

        if (left->peer || right->peer) {
                struct usb_port *lpeer = left->peer;
                struct usb_port *rpeer = right->peer;
                char *method;

                if (left->location && left->location == right->location)
                        method = "location";
                else
                        method = "default";

                pr_debug("usb: failed to peer %s and %s by %s (%s:%s) (%s:%s)\n",
                        dev_name(&left->dev), dev_name(&right->dev), method,
                        dev_name(&left->dev),
                        lpeer ? dev_name(&lpeer->dev) : "none",
                        dev_name(&right->dev),
                        rpeer ? dev_name(&rpeer->dev) : "none");
                return -EBUSY;
        }

        rc = sysfs_create_link(&left->dev.kobj, &right->dev.kobj, "peer");
        if (rc)
                return rc;
        rc = sysfs_create_link(&right->dev.kobj, &left->dev.kobj, "peer");
        if (rc) {
                sysfs_remove_link(&left->dev.kobj, "peer");
                return rc;
        }

        /*
         * We need to wake the HiSpeed port to make sure we don't race
         * setting ->peer with usb_port_runtime_suspend().  Otherwise we
         * may miss a suspend event for the SuperSpeed port.
         */
        if (left->is_superspeed) {
                ss_port = left;
                WARN_ON(right->is_superspeed);
                hs_port = right;
        } else {
                ss_port = right;
                WARN_ON(!right->is_superspeed);
                hs_port = left;
        }
        pm_runtime_get_sync(&hs_port->dev);

        left->peer = right;
        right->peer = left;

        /*
         * The SuperSpeed reference is dropped when the HiSpeed port in
         * this relationship suspends, i.e. when it is safe to allow a
         * SuperSpeed connection to drop since there is no risk of a
         * device degrading to its powered-off HiSpeed connection.
         *
         * Also, drop the HiSpeed ref taken above.
         */
        pm_runtime_get_sync(&ss_port->dev);
        pm_runtime_put(&hs_port->dev);

        return 0;
}

static void link_peers_report(struct usb_port *left, struct usb_port *right)
{
        int rc;

        rc = link_peers(left, right);
        if (rc == 0) {
                dev_dbg(&left->dev, "peered to %s\n", dev_name(&right->dev));
        } else {
                dev_dbg(&left->dev, "failed to peer to %s (%d)\n",
                                dev_name(&right->dev), rc);
                pr_warn_once("usb: port power management may be unreliable\n");
                usb_port_block_power_off = 1;
        }
}

static void unlink_peers(struct usb_port *left, struct usb_port *right)
{
        struct usb_port *ss_port, *hs_port;

        WARN(right->peer != left || left->peer != right,
                        "%s and %s are not peers?\n",
                        dev_name(&left->dev), dev_name(&right->dev));

        /*
         * We wake the HiSpeed port to make sure we don't race its
         * usb_port_runtime_resume() event which takes a SuperSpeed ref
         * when ->peer is !NULL.
         */
        if (left->is_superspeed) {
                ss_port = left;
                hs_port = right;
        } else {
                ss_port = right;
                hs_port = left;
        }

        pm_runtime_get_sync(&hs_port->dev);

        sysfs_remove_link(&left->dev.kobj, "peer");
        right->peer = NULL;
        sysfs_remove_link(&right->dev.kobj, "peer");
        left->peer = NULL;

        /* Drop the SuperSpeed ref held on behalf of the active HiSpeed port */
        pm_runtime_put(&ss_port->dev);

        /* Drop the ref taken above */
        pm_runtime_put(&hs_port->dev);
}

/*
 * For each usb hub device in the system check to see if it is in the
 * peer domain of the given port_dev, and if it is check to see if it
 * has a port that matches the given port by location
 */
static int match_location(struct usb_device *peer_hdev, void *p)
{
        int port1;
        struct usb_hcd *hcd, *peer_hcd;
        struct usb_port *port_dev = p, *peer;
        struct usb_hub *peer_hub = usb_hub_to_struct_hub(peer_hdev);
        struct usb_device *hdev = to_usb_device(port_dev->dev.parent->parent);

        if (!peer_hub)
                return 0;

        hcd = bus_to_hcd(hdev->bus);
        peer_hcd = bus_to_hcd(peer_hdev->bus);
        /* peer_hcd is provisional until we verify it against the known peer */
        if (peer_hcd != hcd->shared_hcd)
                return 0;

        for (port1 = 1; port1 <= peer_hdev->maxchild; port1++) {
                peer = peer_hub->ports[port1 - 1];
                if (peer && peer->location == port_dev->location) {
                        link_peers_report(port_dev, peer);
                        return 1; /* done */
                }
        }

        return 0;
}

/*
 * Find the peer port either via explicit platform firmware "location"
 * data, the peer hcd for root hubs, or the upstream peer relationship
 * for all other hubs.
 */
static void find_and_link_peer(struct usb_hub *hub, int port1)
{
        struct usb_port *port_dev = hub->ports[port1 - 1], *peer;
        struct usb_device *hdev = hub->hdev;
        struct usb_device *peer_hdev;
        struct usb_hub *peer_hub;

        /*
         * If location data is available then we can only peer this port
         * by a location match, not the default peer (lest we create a
         * situation where we need to go back and undo a default peering
         * when the port is later peered by location data)
         */
        if (port_dev->location) {
                /* we link the peer in match_location() if found */
                usb_for_each_dev(port_dev, match_location);
                return;
        } else if (!hdev->parent) {
                struct usb_hcd *hcd = bus_to_hcd(hdev->bus);
                struct usb_hcd *peer_hcd = hcd->shared_hcd;

                if (!peer_hcd)
                        return;

                peer_hdev = peer_hcd->self.root_hub;
        } else {
                struct usb_port *upstream;
                struct usb_device *parent = hdev->parent;
                struct usb_hub *parent_hub = usb_hub_to_struct_hub(parent);

                if (!parent_hub)
                        return;

                upstream = parent_hub->ports[hdev->portnum - 1];
                if (!upstream || !upstream->peer)
                        return;

                peer_hdev = upstream->peer->child;
        }

        peer_hub = usb_hub_to_struct_hub(peer_hdev);
        if (!peer_hub || port1 > peer_hdev->maxchild)
                return;

        /*
         * we found a valid default peer, last check is to make sure it
         * does not have location data
         */
        peer = peer_hub->ports[port1 - 1];
        if (peer && peer->location == 0)
                link_peers_report(port_dev, peer);
}

int usb_hub_create_port_device(struct usb_hub *hub, int port1)
{
        struct usb_port *port_dev;
        int retval;

        port_dev = kzalloc(sizeof(*port_dev), GFP_KERNEL);
        if (!port_dev)
                return -ENOMEM;

        port_dev->req = kzalloc(sizeof(*(port_dev->req)), GFP_KERNEL);
        if (!port_dev->req) {
                kfree(port_dev);
                return -ENOMEM;
        }

        hub->ports[port1 - 1] = port_dev;
        port_dev->portnum = port1;
        set_bit(port1, hub->power_bits);
        port_dev->dev.parent = hub->intfdev;
        port_dev->dev.groups = port_dev_group;
        port_dev->dev.type = &usb_port_device_type;
        port_dev->dev.driver = &usb_port_driver;
        if (hub_is_superspeed(hub->hdev))
                port_dev->is_superspeed = 1;
        dev_set_name(&port_dev->dev, "%s-port%d", dev_name(&hub->hdev->dev),
                        port1);
        mutex_init(&port_dev->status_lock);
        retval = device_register(&port_dev->dev);
        if (retval) {
                put_device(&port_dev->dev);
                return retval;
        }

        /* Set default policy of port-poweroff disabled. */
        retval = dev_pm_qos_add_request(&port_dev->dev, port_dev->req,
                        DEV_PM_QOS_FLAGS, PM_QOS_FLAG_NO_POWER_OFF);
        if (retval < 0) {
                device_unregister(&port_dev->dev);
                return retval;
        }

        find_and_link_peer(hub, port1);

        /*
         * Enable runtime pm and hold a refernce that hub_configure()
         * will drop once the PM_QOS_NO_POWER_OFF flag state has been set
         * and the hub has been fully registered (hdev->maxchild set).
         */
        pm_runtime_set_active(&port_dev->dev);
        pm_runtime_get_noresume(&port_dev->dev);
        pm_runtime_enable(&port_dev->dev);
        device_enable_async_suspend(&port_dev->dev);

        /*
         * Keep hidden the ability to enable port-poweroff if the hub
         * does not support power switching.
         */
        if (!hub_is_port_power_switchable(hub))
                return 0;

        /* Attempt to let userspace take over the policy. */
        retval = dev_pm_qos_expose_flags(&port_dev->dev,
                        PM_QOS_FLAG_NO_POWER_OFF);
        if (retval < 0) {
                dev_warn(&port_dev->dev, "failed to expose pm_qos_no_poweroff\n");
                return 0;
        }

        /* Userspace owns the policy, drop the kernel 'no_poweroff' request. */
        retval = dev_pm_qos_remove_request(port_dev->req);
        if (retval >= 0) {
                kfree(port_dev->req);
                port_dev->req = NULL;
        }
        return 0;
}

void usb_hub_remove_port_device(struct usb_hub *hub, int port1)
{
        struct usb_port *port_dev = hub->ports[port1 - 1];
        struct usb_port *peer;

        peer = port_dev->peer;
        if (peer)
                unlink_peers(port_dev, peer);
        device_unregister(&port_dev->dev);
}