// SPDX-License-Identifier: GPL-2.0
/* Copyright (C) 2017 Netronome Systems, Inc.
 * Copyright (C) 2019 Mellanox Technologies. All rights reserved
 */

#include <linux/completion.h>
#include <linux/device.h>
#include <linux/idr.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/refcount.h>
#include <linux/slab.h>
#include <linux/sysfs.h>

#include "netdevsim.h"

static DEFINE_IDA(nsim_bus_dev_ids);
static LIST_HEAD(nsim_bus_dev_list);
static DEFINE_MUTEX(nsim_bus_dev_list_lock);
static bool nsim_bus_enable;
static refcount_t nsim_bus_devs; /* Including the bus itself. */
static DECLARE_COMPLETION(nsim_bus_devs_released);

static struct nsim_bus_dev *to_nsim_bus_dev(struct device *dev)
{
        return container_of(dev, struct nsim_bus_dev, dev);
}

static ssize_t
nsim_bus_dev_numvfs_store(struct device *dev, struct device_attribute *attr,
                          const char *buf, size_t count)
{
        struct nsim_bus_dev *nsim_bus_dev = to_nsim_bus_dev(dev);
        unsigned int num_vfs;
        int ret;

        ret = kstrtouint(buf, 0, &num_vfs);
        if (ret)
                return ret;

        device_lock(dev);
        ret = -ENOENT;
        if (dev_get_drvdata(dev))
                ret = nsim_drv_configure_vfs(nsim_bus_dev, num_vfs);
        device_unlock(dev);

        return ret ? ret : count;
}

static ssize_t
nsim_bus_dev_numvfs_show(struct device *dev,
                         struct device_attribute *attr, char *buf)
{
        struct nsim_bus_dev *nsim_bus_dev = to_nsim_bus_dev(dev);

        return sprintf(buf, "%u\n", nsim_bus_dev->num_vfs);
}

static struct device_attribute nsim_bus_dev_numvfs_attr =
        __ATTR(sriov_numvfs, 0664, nsim_bus_dev_numvfs_show,
               nsim_bus_dev_numvfs_store);

static ssize_t
new_port_store(struct device *dev, struct device_attribute *attr,
               const char *buf, size_t count)
{
        struct nsim_bus_dev *nsim_bus_dev = to_nsim_bus_dev(dev);
        u8 eth_addr[ETH_ALEN] = {};
        unsigned int port_index;
        bool addr_set = false;
        int ret;

        /* Prevent to use nsim_bus_dev before initialization. */
        if (!smp_load_acquire(&nsim_bus_dev->init))
                return -EBUSY;

        ret = sscanf(buf, "%u %hhx:%hhx:%hhx:%hhx:%hhx:%hhx", &port_index,
                     &eth_addr[0], &eth_addr[1], &eth_addr[2], &eth_addr[3],
                     &eth_addr[4], &eth_addr[5]);
        switch (ret) {
        case 7:
                if (!is_valid_ether_addr(eth_addr)) {
                        pr_err("The supplied perm_addr is not a valid MAC address\n");
                        return -EINVAL;
                }
                addr_set = true;
                fallthrough;
        case 1:
                break;
        default:
                pr_err("Format for adding new port is \"id [perm_addr]\" (uint MAC).\n");
                return -EINVAL;
        }

        ret = nsim_drv_port_add(nsim_bus_dev, NSIM_DEV_PORT_TYPE_PF, port_index,
                                addr_set ? eth_addr : NULL);
        return ret ? ret : count;
}

static struct device_attribute nsim_bus_dev_new_port_attr = __ATTR_WO(new_port);

static ssize_t
del_port_store(struct device *dev, struct device_attribute *attr,
               const char *buf, size_t count)
{
        struct nsim_bus_dev *nsim_bus_dev = to_nsim_bus_dev(dev);
        unsigned int port_index;
        int ret;

        /* Prevent to use nsim_bus_dev before initialization. */
        if (!smp_load_acquire(&nsim_bus_dev->init))
                return -EBUSY;
        ret = kstrtouint(buf, 0, &port_index);
        if (ret)
                return ret;

        ret = nsim_drv_port_del(nsim_bus_dev, NSIM_DEV_PORT_TYPE_PF, port_index);
        return ret ? ret : count;
}

static struct device_attribute nsim_bus_dev_del_port_attr = __ATTR_WO(del_port);

static struct attribute *nsim_bus_dev_attrs[] = {
        &nsim_bus_dev_numvfs_attr.attr,
        &nsim_bus_dev_new_port_attr.attr,
        &nsim_bus_dev_del_port_attr.attr,
        NULL,
};

static const struct attribute_group nsim_bus_dev_attr_group = {
        .attrs = nsim_bus_dev_attrs,
};

static const struct attribute_group *nsim_bus_dev_attr_groups[] = {
        &nsim_bus_dev_attr_group,
        NULL,
};

static void nsim_bus_dev_release(struct device *dev)
{
        struct nsim_bus_dev *nsim_bus_dev;

        nsim_bus_dev = container_of(dev, struct nsim_bus_dev, dev);
        kfree(nsim_bus_dev);
        if (refcount_dec_and_test(&nsim_bus_devs))
                complete(&nsim_bus_devs_released);
}

static const struct device_type nsim_bus_dev_type = {
        .groups = nsim_bus_dev_attr_groups,
        .release = nsim_bus_dev_release,
};

static struct nsim_bus_dev *
nsim_bus_dev_new(unsigned int id, unsigned int port_count, unsigned int num_queues);

static ssize_t
new_device_store(const struct bus_type *bus, const char *buf, size_t count)
{
        unsigned int id, port_count, num_queues;
        struct nsim_bus_dev *nsim_bus_dev;
        int err;

        err = sscanf(buf, "%u %u %u", &id, &port_count, &num_queues);
        switch (err) {
        case 1:
                port_count = 1;
                fallthrough;
        case 2:
                num_queues = 1;
                fallthrough;
        case 3:
                if (id > INT_MAX) {
                        pr_err("Value of \"id\" is too big.\n");
                        return -EINVAL;
                }
                break;
        default:
                pr_err("Format for adding new device is \"id port_count num_queues\" (uint uint unit).\n");
                return -EINVAL;
        }

        mutex_lock(&nsim_bus_dev_list_lock);
        /* Prevent to use resource before initialization. */
        if (!smp_load_acquire(&nsim_bus_enable)) {
                err = -EBUSY;
                goto err;
        }

        nsim_bus_dev = nsim_bus_dev_new(id, port_count, num_queues);
        if (IS_ERR(nsim_bus_dev)) {
                err = PTR_ERR(nsim_bus_dev);
                goto err;
        }

        refcount_inc(&nsim_bus_devs);
        /* Allow using nsim_bus_dev */
        smp_store_release(&nsim_bus_dev->init, true);

        list_add_tail(&nsim_bus_dev->list, &nsim_bus_dev_list);
        mutex_unlock(&nsim_bus_dev_list_lock);

        return count;
err:
        mutex_unlock(&nsim_bus_dev_list_lock);
        return err;
}
static BUS_ATTR_WO(new_device);

static void nsim_bus_dev_del(struct nsim_bus_dev *nsim_bus_dev);

static ssize_t
del_device_store(const struct bus_type *bus, const char *buf, size_t count)
{
        struct nsim_bus_dev *nsim_bus_dev, *tmp;
        unsigned int id;
        int err;

        err = sscanf(buf, "%u", &id);
        switch (err) {
        case 1:
                if (id > INT_MAX) {
                        pr_err("Value of \"id\" is too big.\n");
                        return -EINVAL;
                }
                break;
        default:
                pr_err("Format for deleting device is \"id\" (uint).\n");
                return -EINVAL;
        }

        err = -ENOENT;
        mutex_lock(&nsim_bus_dev_list_lock);
        /* Prevent to use resource before initialization. */
        if (!smp_load_acquire(&nsim_bus_enable)) {
                mutex_unlock(&nsim_bus_dev_list_lock);
                return -EBUSY;
        }
        list_for_each_entry_safe(nsim_bus_dev, tmp, &nsim_bus_dev_list, list) {
                if (nsim_bus_dev->dev.id != id)
                        continue;
                list_del(&nsim_bus_dev->list);
                nsim_bus_dev_del(nsim_bus_dev);
                err = 0;
                break;
        }
        mutex_unlock(&nsim_bus_dev_list_lock);
        return !err ? count : err;
}
static BUS_ATTR_WO(del_device);

static ssize_t link_device_store(const struct bus_type *bus, const char *buf, size_t count)
{
        struct netdevsim *nsim_a, *nsim_b, *peer;
        struct net_device *dev_a, *dev_b;
        unsigned int ifidx_a, ifidx_b;
        int netnsfd_a, netnsfd_b, err;
        struct net *ns_a, *ns_b;

        err = sscanf(buf, "%d:%u %d:%u", &netnsfd_a, &ifidx_a, &netnsfd_b,
                     &ifidx_b);
        if (err != 4) {
                pr_err("Format for linking two devices is \"netnsfd_a:ifidx_a netnsfd_b:ifidx_b\" (int uint int uint).\n");
                return -EINVAL;
        }

        ns_a = get_net_ns_by_fd(netnsfd_a);
        if (IS_ERR(ns_a)) {
                pr_err("Could not find netns with fd: %d\n", netnsfd_a);
                return -EINVAL;
        }

        ns_b = get_net_ns_by_fd(netnsfd_b);
        if (IS_ERR(ns_b)) {
                pr_err("Could not find netns with fd: %d\n", netnsfd_b);
                put_net(ns_a);
                return -EINVAL;
        }

        err = -EINVAL;
        rtnl_lock();
        dev_a = __dev_get_by_index(ns_a, ifidx_a);
        if (!dev_a) {
                pr_err("Could not find device with ifindex %u in netnsfd %d\n",
                       ifidx_a, netnsfd_a);
                goto out_err;
        }

        if (!netdev_is_nsim(dev_a)) {
                pr_err("Device with ifindex %u in netnsfd %d is not a netdevsim\n",
                       ifidx_a, netnsfd_a);
                goto out_err;
        }

        dev_b = __dev_get_by_index(ns_b, ifidx_b);
        if (!dev_b) {
                pr_err("Could not find device with ifindex %u in netnsfd %d\n",
                       ifidx_b, netnsfd_b);
                goto out_err;
        }

        if (!netdev_is_nsim(dev_b)) {
                pr_err("Device with ifindex %u in netnsfd %d is not a netdevsim\n",
                       ifidx_b, netnsfd_b);
                goto out_err;
        }

        if (dev_a == dev_b) {
                pr_err("Cannot link a netdevsim to itself\n");
                goto out_err;
        }

        err = -EBUSY;
        nsim_a = netdev_priv(dev_a);
        peer = rtnl_dereference(nsim_a->peer);
        if (peer) {
                pr_err("Netdevsim %d:%u is already linked\n", netnsfd_a,
                       ifidx_a);
                goto out_err;
        }

        nsim_b = netdev_priv(dev_b);
        peer = rtnl_dereference(nsim_b->peer);
        if (peer) {
                pr_err("Netdevsim %d:%u is already linked\n", netnsfd_b,
                       ifidx_b);
                goto out_err;
        }

        err = 0;
        rcu_assign_pointer(nsim_a->peer, nsim_b);
        rcu_assign_pointer(nsim_b->peer, nsim_a);

        if (netif_running(dev_a) && netif_running(dev_b)) {
                netif_carrier_on(dev_a);
                netif_carrier_on(dev_b);
        }

out_err:
        put_net(ns_b);
        put_net(ns_a);
        rtnl_unlock();

        return !err ? count : err;
}
static BUS_ATTR_WO(link_device);

static ssize_t unlink_device_store(const struct bus_type *bus, const char *buf, size_t count)
{
        struct netdevsim *nsim, *peer;
        struct net_device *dev;
        unsigned int ifidx;
        int netnsfd, err;
        struct net *ns;

        err = sscanf(buf, "%u:%u", &netnsfd, &ifidx);
        if (err != 2) {
                pr_err("Format for unlinking a device is \"netnsfd:ifidx\" (int uint).\n");
                return -EINVAL;
        }

        ns = get_net_ns_by_fd(netnsfd);
        if (IS_ERR(ns)) {
                pr_err("Could not find netns with fd: %d\n", netnsfd);
                return -EINVAL;
        }

        err = -EINVAL;
        rtnl_lock();
        dev = __dev_get_by_index(ns, ifidx);
        if (!dev) {
                pr_err("Could not find device with ifindex %u in netnsfd %d\n",
                       ifidx, netnsfd);
                goto out_put_netns;
        }

        if (!netdev_is_nsim(dev)) {
                pr_err("Device with ifindex %u in netnsfd %d is not a netdevsim\n",
                       ifidx, netnsfd);
                goto out_put_netns;
        }

        nsim = netdev_priv(dev);
        peer = rtnl_dereference(nsim->peer);
        if (!peer)
                goto out_put_netns;

        netif_carrier_off(dev);
        netif_carrier_off(peer->netdev);

        err = 0;
        RCU_INIT_POINTER(nsim->peer, NULL);
        RCU_INIT_POINTER(peer->peer, NULL);
        synchronize_net();
        netif_tx_wake_all_queues(dev);
        netif_tx_wake_all_queues(peer->netdev);

out_put_netns:
        put_net(ns);
        rtnl_unlock();

        return !err ? count : err;
}
static BUS_ATTR_WO(unlink_device);

static struct attribute *nsim_bus_attrs[] = {
        &bus_attr_new_device.attr,
        &bus_attr_del_device.attr,
        &bus_attr_link_device.attr,
        &bus_attr_unlink_device.attr,
        NULL
};
ATTRIBUTE_GROUPS(nsim_bus);

static int nsim_bus_probe(struct device *dev)
{
        struct nsim_bus_dev *nsim_bus_dev = to_nsim_bus_dev(dev);

        return nsim_drv_probe(nsim_bus_dev);
}

static void nsim_bus_remove(struct device *dev)
{
        struct nsim_bus_dev *nsim_bus_dev = to_nsim_bus_dev(dev);

        nsim_drv_remove(nsim_bus_dev);
}

static int nsim_num_vf(struct device *dev)
{
        struct nsim_bus_dev *nsim_bus_dev = to_nsim_bus_dev(dev);

        return nsim_bus_dev->num_vfs;
}

static const struct bus_type nsim_bus = {
        .name           = DRV_NAME,
        .dev_name       = DRV_NAME,
        .bus_groups     = nsim_bus_groups,
        .probe          = nsim_bus_probe,
        .remove         = nsim_bus_remove,
        .num_vf         = nsim_num_vf,
};

#define NSIM_BUS_DEV_MAX_VFS 4

static struct nsim_bus_dev *
nsim_bus_dev_new(unsigned int id, unsigned int port_count, unsigned int num_queues)
{
        struct nsim_bus_dev *nsim_bus_dev;
        int err;

        nsim_bus_dev = kzalloc_obj(*nsim_bus_dev);
        if (!nsim_bus_dev)
                return ERR_PTR(-ENOMEM);

        err = ida_alloc_range(&nsim_bus_dev_ids, id, id, GFP_KERNEL);
        if (err < 0)
                goto err_nsim_bus_dev_free;
        nsim_bus_dev->dev.id = err;
        nsim_bus_dev->dev.bus = &nsim_bus;
        nsim_bus_dev->dev.type = &nsim_bus_dev_type;
        nsim_bus_dev->port_count = port_count;
        nsim_bus_dev->num_queues = num_queues;
        nsim_bus_dev->initial_net = current->nsproxy->net_ns;
        nsim_bus_dev->max_vfs = NSIM_BUS_DEV_MAX_VFS;
        /* Disallow using nsim_bus_dev */
        smp_store_release(&nsim_bus_dev->init, false);

        err = device_register(&nsim_bus_dev->dev);
        if (err)
                goto err_nsim_bus_dev_id_free;

        return nsim_bus_dev;

err_nsim_bus_dev_id_free:
        ida_free(&nsim_bus_dev_ids, nsim_bus_dev->dev.id);
        put_device(&nsim_bus_dev->dev);
        nsim_bus_dev = NULL;
err_nsim_bus_dev_free:
        kfree(nsim_bus_dev);
        return ERR_PTR(err);
}

static void nsim_bus_dev_del(struct nsim_bus_dev *nsim_bus_dev)
{
        /* Disallow using nsim_bus_dev */
        smp_store_release(&nsim_bus_dev->init, false);
        ida_free(&nsim_bus_dev_ids, nsim_bus_dev->dev.id);
        device_unregister(&nsim_bus_dev->dev);
}

static struct device_driver nsim_driver = {
        .name           = DRV_NAME,
        .bus            = &nsim_bus,
        .owner          = THIS_MODULE,
};

int nsim_bus_init(void)
{
        int err;

        err = bus_register(&nsim_bus);
        if (err)
                return err;
        err = driver_register(&nsim_driver);
        if (err)
                goto err_bus_unregister;
        refcount_set(&nsim_bus_devs, 1);
        /* Allow using resources */
        smp_store_release(&nsim_bus_enable, true);
        return 0;

err_bus_unregister:
        bus_unregister(&nsim_bus);
        return err;
}

void nsim_bus_exit(void)
{
        struct nsim_bus_dev *nsim_bus_dev, *tmp;

        /* Disallow using resources */
        smp_store_release(&nsim_bus_enable, false);
        if (refcount_dec_and_test(&nsim_bus_devs))
                complete(&nsim_bus_devs_released);

        mutex_lock(&nsim_bus_dev_list_lock);
        list_for_each_entry_safe(nsim_bus_dev, tmp, &nsim_bus_dev_list, list) {
                list_del(&nsim_bus_dev->list);
                nsim_bus_dev_del(nsim_bus_dev);
        }
        mutex_unlock(&nsim_bus_dev_list_lock);

        wait_for_completion(&nsim_bus_devs_released);

        driver_unregister(&nsim_driver);
        bus_unregister(&nsim_bus);
}