// SPDX-License-Identifier: GPL-2.0
/*
 * Thunderbolt driver - path/tunnel functionality
 *
 * Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>
 * Copyright (C) 2019, Intel Corporation
 */

#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/delay.h>
#include <linux/ktime.h>

#include "tb.h"

static void tb_dump_hop(const struct tb_path_hop *hop, const struct tb_regs_hop *regs)
{
        const struct tb_port *port = hop->in_port;

        tb_port_dbg(port, " In HopID: %d => Out port: %d Out HopID: %d\n",
                    hop->in_hop_index, regs->out_port, regs->next_hop);
        tb_port_dbg(port, "  Weight: %d Priority: %d Credits: %d Drop: %d PM: %d\n",
                    regs->weight, regs->priority, regs->initial_credits,
                    regs->drop_packages, regs->pmps);
        tb_port_dbg(port, "   Counter enabled: %d Counter index: %d\n",
                    regs->counter_enable, regs->counter);
        tb_port_dbg(port, "  Flow Control (In/Eg): %d/%d Shared Buffer (In/Eg): %d/%d\n",
                    regs->ingress_fc, regs->egress_fc,
                    regs->ingress_shared_buffer, regs->egress_shared_buffer);
        tb_port_dbg(port, "  Unknown1: %#x Unknown2: %#x Unknown3: %#x\n",
                    regs->unknown1, regs->unknown2, regs->unknown3);
}

static struct tb_port *tb_path_find_dst_port(struct tb_port *src, int src_hopid,
                                             int dst_hopid)
{
        struct tb_port *port, *out_port = NULL;
        struct tb_regs_hop hop;
        struct tb_switch *sw;
        int i, ret, hopid;

        hopid = src_hopid;
        port = src;

        for (i = 0; port && i < TB_PATH_MAX_HOPS; i++) {
                sw = port->sw;

                ret = tb_port_read(port, &hop, TB_CFG_HOPS, 2 * hopid, 2);
                if (ret) {
                        tb_port_warn(port, "failed to read path at %d\n", hopid);
                        return NULL;
                }

                if (!hop.enable)
                        return NULL;

                out_port = &sw->ports[hop.out_port];
                hopid = hop.next_hop;
                port = out_port->remote;
        }

        return out_port && hopid == dst_hopid ? out_port : NULL;
}

static int tb_path_find_src_hopid(struct tb_port *src,
        const struct tb_port *dst, int dst_hopid)
{
        struct tb_port *out;
        int i;

        for (i = TB_PATH_MIN_HOPID; i <= src->config.max_in_hop_id; i++) {
                out = tb_path_find_dst_port(src, i, dst_hopid);
                if (out == dst)
                        return i;
        }

        return 0;
}

/**
 * tb_path_discover() - Discover a path
 * @src: First input port of a path
 * @src_hopid: Starting HopID of a path (%-1 if don't care)
 * @dst: Expected destination port of the path (%NULL if don't care)
 * @dst_hopid: HopID to the @dst (%-1 if don't care)
 * @last: Last port is filled here if not %NULL
 * @name: Name of the path
 * @alloc_hopid: Allocate HopIDs for the ports
 *
 * Follows a path starting from @src and @src_hopid to the last output
 * port of the path. Allocates HopIDs for the visited ports (if
 * @alloc_hopid is true). Call tb_path_free() to release the path and
 * allocated HopIDs when the path is not needed anymore.
 *
 * Note function discovers also incomplete paths so caller should check
 * that the @dst port is the expected one. If it is not, the path can be
 * cleaned up by calling tb_path_deactivate() before tb_path_free().
 *
 * Return: Pointer to &struct tb_path, %NULL in case of failure.
 */
struct tb_path *tb_path_discover(struct tb_port *src, int src_hopid,
                                 struct tb_port *dst, int dst_hopid,
                                 struct tb_port **last, const char *name,
                                 bool alloc_hopid)
{
        struct tb_port *out_port;
        struct tb_regs_hop hop;
        struct tb_path *path;
        struct tb_switch *sw;
        struct tb_port *p;
        size_t num_hops;
        int ret, i, h;

        if (src_hopid < 0 && dst) {
                /*
                 * For incomplete paths the intermediate HopID can be
                 * different from the one used by the protocol adapter
                 * so in that case find a path that ends on @dst with
                 * matching @dst_hopid. That should give us the correct
                 * HopID for the @src.
                 */
                src_hopid = tb_path_find_src_hopid(src, dst, dst_hopid);
                if (!src_hopid)
                        return NULL;
        }

        p = src;
        h = src_hopid;
        num_hops = 0;

        for (i = 0; p && i < TB_PATH_MAX_HOPS; i++) {
                sw = p->sw;

                ret = tb_port_read(p, &hop, TB_CFG_HOPS, 2 * h, 2);
                if (ret) {
                        tb_port_warn(p, "failed to read path at %d\n", h);
                        return NULL;
                }

                /* If the hop is not enabled we got an incomplete path */
                if (!hop.enable)
                        break;

                out_port = &sw->ports[hop.out_port];
                if (last)
                        *last = out_port;

                h = hop.next_hop;
                p = out_port->remote;
                num_hops++;
        }

        path = kzalloc_obj(*path);
        if (!path)
                return NULL;

        path->name = name;
        path->tb = src->sw->tb;
        path->path_length = num_hops;
        path->activated = true;
        path->alloc_hopid = alloc_hopid;

        path->hops = kzalloc_objs(*path->hops, num_hops);
        if (!path->hops) {
                kfree(path);
                return NULL;
        }

        tb_dbg(path->tb, "discovering %s path starting from %llx:%u\n",
               path->name, tb_route(src->sw), src->port);

        p = src;
        h = src_hopid;

        for (i = 0; i < num_hops; i++) {
                int next_hop;

                sw = p->sw;

                ret = tb_port_read(p, &hop, TB_CFG_HOPS, 2 * h, 2);
                if (ret) {
                        tb_port_warn(p, "failed to read path at %d\n", h);
                        goto err;
                }

                if (alloc_hopid && tb_port_alloc_in_hopid(p, h, h) < 0)
                        goto err;

                out_port = &sw->ports[hop.out_port];
                next_hop = hop.next_hop;

                if (alloc_hopid &&
                    tb_port_alloc_out_hopid(out_port, next_hop, next_hop) < 0) {
                        tb_port_release_in_hopid(p, h);
                        goto err;
                }

                path->hops[i].in_port = p;
                path->hops[i].in_hop_index = h;
                path->hops[i].in_counter_index = -1;
                path->hops[i].out_port = out_port;
                path->hops[i].next_hop_index = next_hop;

                tb_dump_hop(&path->hops[i], &hop);

                h = next_hop;
                p = out_port->remote;
        }

        tb_dbg(path->tb, "path discovery complete\n");
        return path;

err:
        tb_port_warn(src, "failed to discover path starting at HopID %d\n",
                     src_hopid);
        tb_path_free(path);
        return NULL;
}

/**
 * tb_path_alloc() - allocate a thunderbolt path between two ports
 * @tb: Domain pointer
 * @src: Source port of the path
 * @src_hopid: HopID used for the first ingress port in the path
 * @dst: Destination port of the path
 * @dst_hopid: HopID used for the last egress port in the path
 * @link_nr: Preferred link if there are dual links on the path
 * @name: Name of the path
 *
 * Creates path between two ports starting with given @src_hopid. Reserves
 * HopIDs for each port (they can be different from @src_hopid depending on
 * how many HopIDs each port already have reserved). If there are dual
 * links on the path, prioritizes using @link_nr but takes into account
 * that the lanes may be bonded.
 *
 * Return: Pointer to &struct tb_path, %NULL in case of failure.
 */
struct tb_path *tb_path_alloc(struct tb *tb, struct tb_port *src, int src_hopid,
                              struct tb_port *dst, int dst_hopid, int link_nr,
                              const char *name)
{
        struct tb_port *in_port, *out_port, *first_port, *last_port;
        int in_hopid, out_hopid;
        struct tb_path *path;
        size_t num_hops;
        int i, ret;

        path = kzalloc_obj(*path);
        if (!path)
                return NULL;

        first_port = last_port = NULL;
        i = 0;
        tb_for_each_port_on_path(src, dst, in_port) {
                if (!first_port)
                        first_port = in_port;
                last_port = in_port;
                i++;
        }

        /* Check that src and dst are reachable */
        if (first_port != src || last_port != dst) {
                kfree(path);
                return NULL;
        }

        /* Each hop takes two ports */
        num_hops = i / 2;

        path->hops = kzalloc_objs(*path->hops, num_hops);
        if (!path->hops) {
                kfree(path);
                return NULL;
        }

        path->alloc_hopid = true;

        in_hopid = src_hopid;
        out_port = NULL;

        for (i = 0; i < num_hops; i++) {
                in_port = tb_next_port_on_path(src, dst, out_port);
                if (!in_port)
                        goto err;

                /* When lanes are bonded primary link must be used */
                if (!in_port->bonded && in_port->dual_link_port &&
                    in_port->link_nr != link_nr)
                        in_port = in_port->dual_link_port;

                ret = tb_port_alloc_in_hopid(in_port, in_hopid, in_hopid);
                if (ret < 0)
                        goto err;
                in_hopid = ret;

                out_port = tb_next_port_on_path(src, dst, in_port);
                if (!out_port)
                        goto err;

                /*
                 * Pick up right port when going from non-bonded to
                 * bonded or from bonded to non-bonded.
                 */
                if (out_port->dual_link_port) {
                        if (!in_port->bonded && out_port->bonded &&
                            out_port->link_nr) {
                                /*
                                 * Use primary link when going from
                                 * non-bonded to bonded.
                                 */
                                out_port = out_port->dual_link_port;
                        } else if (!out_port->bonded &&
                                   out_port->link_nr != link_nr) {
                                /*
                                 * If out port is not bonded follow
                                 * link_nr.
                                 */
                                out_port = out_port->dual_link_port;
                        }
                }

                if (i == num_hops - 1)
                        ret = tb_port_alloc_out_hopid(out_port, dst_hopid,
                                                      dst_hopid);
                else
                        ret = tb_port_alloc_out_hopid(out_port, -1, -1);

                if (ret < 0)
                        goto err;
                out_hopid = ret;

                path->hops[i].in_hop_index = in_hopid;
                path->hops[i].in_port = in_port;
                path->hops[i].in_counter_index = -1;
                path->hops[i].out_port = out_port;
                path->hops[i].next_hop_index = out_hopid;

                in_hopid = out_hopid;
        }

        path->tb = tb;
        path->path_length = num_hops;
        path->name = name;

        return path;

err:
        tb_path_free(path);
        return NULL;
}

/**
 * tb_path_free() - free a path
 * @path: Path to free
 *
 * Frees a path. The path does not need to be deactivated.
 */
void tb_path_free(struct tb_path *path)
{
        if (path->alloc_hopid) {
                int i;

                for (i = 0; i < path->path_length; i++) {
                        const struct tb_path_hop *hop = &path->hops[i];

                        if (hop->in_port)
                                tb_port_release_in_hopid(hop->in_port,
                                                         hop->in_hop_index);
                        if (hop->out_port)
                                tb_port_release_out_hopid(hop->out_port,
                                                          hop->next_hop_index);
                }
        }

        kfree(path->hops);
        kfree(path);
}

static void __tb_path_deallocate_nfc(struct tb_path *path, int first_hop)
{
        int i, res;
        for (i = first_hop; i < path->path_length; i++) {
                res = tb_port_add_nfc_credits(path->hops[i].in_port,
                                              -path->hops[i].nfc_credits);
                if (res)
                        tb_port_warn(path->hops[i].in_port,
                                     "nfc credits deallocation failed for hop %d\n",
                                     i);
        }
}

static int __tb_path_deactivate_hop(struct tb_port *port, int hop_index,
                                    bool clear_fc)
{
        struct tb_regs_hop hop;
        ktime_t timeout;
        int ret;

        /* Disable the path */
        ret = tb_port_read(port, &hop, TB_CFG_HOPS, 2 * hop_index, 2);
        if (ret)
                return ret;

        /* Already disabled */
        if (!hop.enable)
                return 0;

        hop.enable = 0;

        ret = tb_port_write(port, &hop, TB_CFG_HOPS, 2 * hop_index, 2);
        if (ret)
                return ret;

        /* Wait until it is drained */
        timeout = ktime_add_ms(ktime_get(), 500);
        do {
                ret = tb_port_read(port, &hop, TB_CFG_HOPS, 2 * hop_index, 2);
                if (ret)
                        return ret;

                if (!hop.pending) {
                        if (clear_fc) {
                                /*
                                 * Clear flow control. Protocol adapters
                                 * IFC and ISE bits are vendor defined
                                 * in the USB4 spec so we clear them
                                 * only for pre-USB4 adapters.
                                 */
                                if (!tb_switch_is_usb4(port->sw)) {
                                        hop.ingress_fc = 0;
                                        hop.ingress_shared_buffer = 0;
                                }
                                hop.egress_fc = 0;
                                hop.egress_shared_buffer = 0;

                                return tb_port_write(port, &hop, TB_CFG_HOPS,
                                                     2 * hop_index, 2);
                        }

                        return 0;
                }

                usleep_range(10, 20);
        } while (ktime_before(ktime_get(), timeout));

        return -ETIMEDOUT;
}

/**
 * tb_path_deactivate_hop() - Deactivate one path in path config space
 * @port: Lane or protocol adapter
 * @hop_index: HopID of the path to be cleared
 *
 * This deactivates or clears a single path config space entry at
 * @hop_index.
 *
 * Return: %0 on success, negative errno otherwise.
 */
int tb_path_deactivate_hop(struct tb_port *port, int hop_index)
{
        return __tb_path_deactivate_hop(port, hop_index, true);
}

static void __tb_path_deactivate_hops(struct tb_path *path, int first_hop)
{
        int i, res;

        for (i = first_hop; i < path->path_length; i++) {
                res = __tb_path_deactivate_hop(path->hops[i].in_port,
                                               path->hops[i].in_hop_index,
                                               path->clear_fc);
                if (res && res != -ENODEV)
                        tb_port_warn(path->hops[i].in_port,
                                     "hop deactivation failed for hop %d, index %d\n",
                                     i, path->hops[i].in_hop_index);
        }
}

void tb_path_deactivate(struct tb_path *path)
{
        if (!path->activated) {
                tb_WARN(path->tb, "trying to deactivate an inactive path\n");
                return;
        }
        tb_dbg(path->tb,
               "deactivating %s path from %llx:%u to %llx:%u\n",
               path->name, tb_route(path->hops[0].in_port->sw),
               path->hops[0].in_port->port,
               tb_route(path->hops[path->path_length - 1].out_port->sw),
               path->hops[path->path_length - 1].out_port->port);
        __tb_path_deactivate_hops(path, 0);
        __tb_path_deallocate_nfc(path, 0);
        path->activated = false;
}

/**
 * tb_path_activate() - activate a path
 * @path: Path to activate
 *
 * Activate a path starting with the last hop and iterating backwards. The
 * caller must fill path->hops before calling tb_path_activate().
 *
 * Return: %0 on success, negative errno otherwise.
 */
int tb_path_activate(struct tb_path *path)
{
        int i, res;
        enum tb_path_port out_mask, in_mask;
        if (path->activated) {
                tb_WARN(path->tb, "trying to activate already activated path\n");
                return -EINVAL;
        }

        tb_dbg(path->tb,
               "activating %s path from %llx:%u to %llx:%u\n",
               path->name, tb_route(path->hops[0].in_port->sw),
               path->hops[0].in_port->port,
               tb_route(path->hops[path->path_length - 1].out_port->sw),
               path->hops[path->path_length - 1].out_port->port);

        /* Clear counters. */
        for (i = path->path_length - 1; i >= 0; i--) {
                if (path->hops[i].in_counter_index == -1)
                        continue;
                res = tb_port_clear_counter(path->hops[i].in_port,
                                            path->hops[i].in_counter_index);
                if (res)
                        goto err;
        }

        /* Add non flow controlled credits. */
        for (i = path->path_length - 1; i >= 0; i--) {
                res = tb_port_add_nfc_credits(path->hops[i].in_port,
                                              path->hops[i].nfc_credits);
                if (res) {
                        __tb_path_deallocate_nfc(path, i);
                        goto err;
                }
        }

        /* Activate hops. */
        for (i = path->path_length - 1; i >= 0; i--) {
                struct tb_regs_hop hop = { 0 };

                /* If it is left active deactivate it first */
                __tb_path_deactivate_hop(path->hops[i].in_port,
                                path->hops[i].in_hop_index, path->clear_fc);

                /* dword 0 */
                hop.next_hop = path->hops[i].next_hop_index;
                hop.out_port = path->hops[i].out_port->port;
                hop.initial_credits = path->hops[i].initial_credits;
                hop.pmps = path->hops[i].pm_support;
                hop.unknown1 = 0;
                hop.enable = 1;

                /* dword 1 */
                out_mask = (i == path->path_length - 1) ?
                                TB_PATH_DESTINATION : TB_PATH_INTERNAL;
                in_mask = (i == 0) ? TB_PATH_SOURCE : TB_PATH_INTERNAL;
                hop.weight = path->weight;
                hop.unknown2 = 0;
                hop.priority = path->priority;
                hop.drop_packages = path->drop_packages;
                hop.counter = path->hops[i].in_counter_index;
                hop.counter_enable = path->hops[i].in_counter_index != -1;
                hop.ingress_fc = path->ingress_fc_enable & in_mask;
                hop.egress_fc = path->egress_fc_enable & out_mask;
                hop.ingress_shared_buffer = path->ingress_shared_buffer
                                            & in_mask;
                hop.egress_shared_buffer = path->egress_shared_buffer
                                            & out_mask;
                hop.unknown3 = 0;

                tb_port_dbg(path->hops[i].in_port, "Writing hop %d\n", i);
                tb_dump_hop(&path->hops[i], &hop);
                res = tb_port_write(path->hops[i].in_port, &hop, TB_CFG_HOPS,
                                    2 * path->hops[i].in_hop_index, 2);
                if (res) {
                        __tb_path_deactivate_hops(path, i);
                        __tb_path_deallocate_nfc(path, 0);
                        goto err;
                }
        }
        path->activated = true;
        tb_dbg(path->tb, "%s path activation complete\n", path->name);
        return 0;
err:
        tb_warn(path->tb, "%s path activation failed: %d\n", path->name, res);
        return res;
}

/**
 * tb_path_is_invalid() - check whether any ports on the path are invalid
 * @path: Path to check
 *
 * Return: %true if the path is invalid, %false otherwise.
 */
bool tb_path_is_invalid(struct tb_path *path)
{
        int i = 0;
        for (i = 0; i < path->path_length; i++) {
                if (path->hops[i].in_port->sw->is_unplugged)
                        return true;
                if (path->hops[i].out_port->sw->is_unplugged)
                        return true;
        }
        return false;
}

/**
 * tb_path_port_on_path() - Does the path go through certain port
 * @path: Path to check
 * @port: Switch to check
 *
 * Goes over all hops on path and checks if @port is any of them.
 * Direction does not matter.
 *
 * Return: %true if port is on the path, %false otherwise.
 */
bool tb_path_port_on_path(const struct tb_path *path, const struct tb_port *port)
{
        int i;

        for (i = 0; i < path->path_length; i++) {
                if (path->hops[i].in_port == port ||
                    path->hops[i].out_port == port)
                        return true;
        }

        return false;
}