// SPDX-License-Identifier: GPL-2.0
/*
 * Thunderbolt driver - bus logic (NHI independent)
 *
 * 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/platform_data/x86/apple.h>

#include "tb.h"
#include "tb_regs.h"
#include "tunnel.h"

/**
 * struct tb_cm - Simple Thunderbolt connection manager
 * @tunnel_list: List of active tunnels
 * @hotplug_active: tb_handle_hotplug will stop progressing plug
 *		    events and exit if this is not set (it needs to
 *		    acquire the lock one more time). Used to drain wq
 *		    after cfg has been paused.
 */
struct tb_cm {
	struct list_head tunnel_list;
	bool hotplug_active;
};

/* enumeration & hot plug handling */

static void tb_discover_tunnels(struct tb_switch *sw)
{
	struct tb *tb = sw->tb;
	struct tb_cm *tcm = tb_priv(tb);
	struct tb_port *port;
	int i;

	for (i = 1; i <= sw->config.max_port_number; i++) {
		struct tb_tunnel *tunnel = NULL;

		port = &sw->ports[i];
		switch (port->config.type) {
		case TB_TYPE_PCIE_DOWN:
			tunnel = tb_tunnel_discover_pci(tb, port);
			break;

		default:
			break;
		}

		if (tunnel) {
			struct tb_switch *parent = tunnel->dst_port->sw;

			while (parent != tunnel->src_port->sw) {
				parent->boot = true;
				parent = tb_switch_parent(parent);
			}

			list_add_tail(&tunnel->list, &tcm->tunnel_list);
		}
	}

	for (i = 1; i <= sw->config.max_port_number; i++) {
		if (tb_port_has_remote(&sw->ports[i]))
			tb_discover_tunnels(sw->ports[i].remote->sw);
	}
}

static void tb_scan_port(struct tb_port *port);

/**
 * tb_scan_switch() - scan for and initialize downstream switches
 */
static void tb_scan_switch(struct tb_switch *sw)
{
	int i;
	for (i = 1; i <= sw->config.max_port_number; i++)
		tb_scan_port(&sw->ports[i]);
}

/**
 * tb_scan_port() - check for and initialize switches below port
 */
static void tb_scan_port(struct tb_port *port)
{
	struct tb_cm *tcm = tb_priv(port->sw->tb);
	struct tb_port *upstream_port;
	struct tb_switch *sw;

	if (tb_is_upstream_port(port))
		return;
	if (port->config.type != TB_TYPE_PORT)
		return;
	if (port->dual_link_port && port->link_nr)
		return; /*
			 * Downstream switch is reachable through two ports.
			 * Only scan on the primary port (link_nr == 0).
			 */
	if (tb_wait_for_port(port, false) <= 0)
		return;
	if (port->remote) {
		tb_port_WARN(port, "port already has a remote!\n");
		return;
	}
	sw = tb_switch_alloc(port->sw->tb, &port->sw->dev,
			     tb_downstream_route(port));
	if (!sw)
		return;

	if (tb_switch_configure(sw)) {
		tb_switch_put(sw);
		return;
	}

	/*
	 * Do not send uevents until we have discovered all existing
	 * tunnels and know which switches were authorized already by
	 * the boot firmware.
	 */
	if (!tcm->hotplug_active)
		dev_set_uevent_suppress(&sw->dev, true);

	if (tb_switch_add(sw)) {
		tb_switch_put(sw);
		return;
	}

	/* Link the switches using both links if available */
	upstream_port = tb_upstream_port(sw);
	port->remote = upstream_port;
	upstream_port->remote = port;
	if (port->dual_link_port && upstream_port->dual_link_port) {
		port->dual_link_port->remote = upstream_port->dual_link_port;
		upstream_port->dual_link_port->remote = port->dual_link_port;
	}

	tb_scan_switch(sw);
}

/**
 * tb_free_invalid_tunnels() - destroy tunnels of devices that have gone away
 */
static void tb_free_invalid_tunnels(struct tb *tb)
{
	struct tb_cm *tcm = tb_priv(tb);
	struct tb_tunnel *tunnel;
	struct tb_tunnel *n;

	list_for_each_entry_safe(tunnel, n, &tcm->tunnel_list, list) {
		if (tb_tunnel_is_invalid(tunnel)) {
			tb_tunnel_deactivate(tunnel);
			list_del(&tunnel->list);
			tb_tunnel_free(tunnel);
		}
	}
}

/**
 * tb_free_unplugged_children() - traverse hierarchy and free unplugged switches
 */
static void tb_free_unplugged_children(struct tb_switch *sw)
{
	int i;
	for (i = 1; i <= sw->config.max_port_number; i++) {
		struct tb_port *port = &sw->ports[i];

		if (!tb_port_has_remote(port))
			continue;

		if (port->remote->sw->is_unplugged) {
			tb_switch_remove(port->remote->sw);
			port->remote = NULL;
			if (port->dual_link_port)
				port->dual_link_port->remote = NULL;
		} else {
			tb_free_unplugged_children(port->remote->sw);
		}
	}
}


/**
 * find_pci_up_port() - return the first PCIe up port on @sw or NULL
 */
static struct tb_port *tb_find_pci_up_port(struct tb_switch *sw)
{
	int i;
	for (i = 1; i <= sw->config.max_port_number; i++)
		if (sw->ports[i].config.type == TB_TYPE_PCIE_UP)
			return &sw->ports[i];
	return NULL;
}

/**
 * find_unused_down_port() - return the first inactive PCIe down port on @sw
 */
static struct tb_port *tb_find_unused_down_port(struct tb_switch *sw)
{
	int i;
	int cap;
	int res;
	int data;
	for (i = 1; i <= sw->config.max_port_number; i++) {
		if (tb_is_upstream_port(&sw->ports[i]))
			continue;
		if (sw->ports[i].config.type != TB_TYPE_PCIE_DOWN)
			continue;
		cap = sw->ports[i].cap_adap;
		if (!cap)
			continue;
		res = tb_port_read(&sw->ports[i], &data, TB_CFG_PORT, cap, 1);
		if (res < 0)
			continue;
		if (data & 0x80000000)
			continue;
		return &sw->ports[i];
	}
	return NULL;
}

static struct tb_port *tb_find_pcie_down(struct tb_switch *sw,
					 const struct tb_port *port)
{
	/*
	 * To keep plugging devices consistently in the same PCIe
	 * hierarchy, do mapping here for root switch downstream PCIe
	 * ports.
	 */
	if (!tb_route(sw)) {
		int phy_port = tb_phy_port_from_link(port->port);
		int index;

		/*
		 * Hard-coded Thunderbolt port to PCIe down port mapping
		 * per controller.
		 */
		if (tb_switch_is_cr(sw))
			index = !phy_port ? 6 : 7;
		else if (tb_switch_is_fr(sw))
			index = !phy_port ? 6 : 8;
		else
			goto out;

		/* Validate the hard-coding */
		if (WARN_ON(index > sw->config.max_port_number))
			goto out;
		if (WARN_ON(!tb_port_is_pcie_down(&sw->ports[index])))
			goto out;
		if (WARN_ON(tb_pci_port_is_enabled(&sw->ports[index])))
			goto out;

		return &sw->ports[index];
	}

out:
	return tb_find_unused_down_port(sw);
}

static int tb_tunnel_pci(struct tb *tb, struct tb_switch *sw)
{
	struct tb_port *up, *down, *port;
	struct tb_cm *tcm = tb_priv(tb);
	struct tb_switch *parent_sw;
	struct tb_tunnel *tunnel;

	up = tb_find_pci_up_port(sw);
	if (!up)
		return 0;

	/*
	 * Look up available down port. Since we are chaining it should
	 * be found right above this switch.
	 */
	parent_sw = tb_to_switch(sw->dev.parent);
	port = tb_port_at(tb_route(sw), parent_sw);
	down = tb_find_pcie_down(parent_sw, port);
	if (!down)
		return 0;

	tunnel = tb_tunnel_alloc_pci(tb, up, down);
	if (!tunnel)
		return -ENOMEM;

	if (tb_tunnel_activate(tunnel)) {
		tb_port_info(up,
			     "PCIe tunnel activation failed, aborting\n");
		tb_tunnel_free(tunnel);
		return -EIO;
	}

	list_add_tail(&tunnel->list, &tcm->tunnel_list);
	return 0;
}

/* hotplug handling */

struct tb_hotplug_event {
	struct work_struct work;
	struct tb *tb;
	u64 route;
	u8 port;
	bool unplug;
};

/**
 * tb_handle_hotplug() - handle hotplug event
 *
 * Executes on tb->wq.
 */
static void tb_handle_hotplug(struct work_struct *work)
{
	struct tb_hotplug_event *ev = container_of(work, typeof(*ev), work);
	struct tb *tb = ev->tb;
	struct tb_cm *tcm = tb_priv(tb);
	struct tb_switch *sw;
	struct tb_port *port;
	mutex_lock(&tb->lock);
	if (!tcm->hotplug_active)
		goto out; /* during init, suspend or shutdown */

	sw = tb_switch_find_by_route(tb, ev->route);
	if (!sw) {
		tb_warn(tb,
			"hotplug event from non existent switch %llx:%x (unplug: %d)\n",
			ev->route, ev->port, ev->unplug);
		goto out;
	}
	if (ev->port > sw->config.max_port_number) {
		tb_warn(tb,
			"hotplug event from non existent port %llx:%x (unplug: %d)\n",
			ev->route, ev->port, ev->unplug);
		goto put_sw;
	}
	port = &sw->ports[ev->port];
	if (tb_is_upstream_port(port)) {
		tb_dbg(tb, "hotplug event for upstream port %llx:%x (unplug: %d)\n",
		       ev->route, ev->port, ev->unplug);
		goto put_sw;
	}
	if (ev->unplug) {
		if (tb_port_has_remote(port)) {
			tb_port_info(port, "unplugged\n");
			tb_sw_set_unplugged(port->remote->sw);
			tb_free_invalid_tunnels(tb);
			tb_switch_remove(port->remote->sw);
			port->remote = NULL;
			if (port->dual_link_port)
				port->dual_link_port->remote = NULL;
		} else {
			tb_port_info(port,
				     "got unplug event for disconnected port, ignoring\n");
		}
	} else if (port->remote) {
		tb_port_info(port,
			     "got plug event for connected port, ignoring\n");
	} else {
		if (tb_port_is_null(port)) {
			tb_port_info(port, "hotplug: scanning\n");
			tb_scan_port(port);
			if (!port->remote)
				tb_port_info(port, "hotplug: no switch found\n");
		}
	}

put_sw:
	tb_switch_put(sw);
out:
	mutex_unlock(&tb->lock);
	kfree(ev);
}

/**
 * tb_schedule_hotplug_handler() - callback function for the control channel
 *
 * Delegates to tb_handle_hotplug.
 */
static void tb_handle_event(struct tb *tb, enum tb_cfg_pkg_type type,
			    const void *buf, size_t size)
{
	const struct cfg_event_pkg *pkg = buf;
	struct tb_hotplug_event *ev;
	u64 route;

	if (type != TB_CFG_PKG_EVENT) {
		tb_warn(tb, "unexpected event %#x, ignoring\n", type);
		return;
	}

	route = tb_cfg_get_route(&pkg->header);

	if (tb_cfg_error(tb->ctl, route, pkg->port,
			 TB_CFG_ERROR_ACK_PLUG_EVENT)) {
		tb_warn(tb, "could not ack plug event on %llx:%x\n", route,
			pkg->port);
	}

	ev = kmalloc(sizeof(*ev), GFP_KERNEL);
	if (!ev)
		return;
	INIT_WORK(&ev->work, tb_handle_hotplug);
	ev->tb = tb;
	ev->route = route;
	ev->port = pkg->port;
	ev->unplug = pkg->unplug;
	queue_work(tb->wq, &ev->work);
}

static void tb_stop(struct tb *tb)
{
	struct tb_cm *tcm = tb_priv(tb);
	struct tb_tunnel *tunnel;
	struct tb_tunnel *n;

	/* tunnels are only present after everything has been initialized */
	list_for_each_entry_safe(tunnel, n, &tcm->tunnel_list, list) {
		tb_tunnel_deactivate(tunnel);
		tb_tunnel_free(tunnel);
	}
	tb_switch_remove(tb->root_switch);
	tcm->hotplug_active = false; /* signal tb_handle_hotplug to quit */
}

static int tb_scan_finalize_switch(struct device *dev, void *data)
{
	if (tb_is_switch(dev)) {
		struct tb_switch *sw = tb_to_switch(dev);

		/*
		 * If we found that the switch was already setup by the
		 * boot firmware, mark it as authorized now before we
		 * send uevent to userspace.
		 */
		if (sw->boot)
			sw->authorized = 1;

		dev_set_uevent_suppress(dev, false);
		kobject_uevent(&dev->kobj, KOBJ_ADD);
		device_for_each_child(dev, NULL, tb_scan_finalize_switch);
	}

	return 0;
}

static int tb_start(struct tb *tb)
{
	struct tb_cm *tcm = tb_priv(tb);
	int ret;

	tb->root_switch = tb_switch_alloc(tb, &tb->dev, 0);
	if (!tb->root_switch)
		return -ENOMEM;

	/*
	 * ICM firmware upgrade needs running firmware and in native
	 * mode that is not available so disable firmware upgrade of the
	 * root switch.
	 */
	tb->root_switch->no_nvm_upgrade = true;

	ret = tb_switch_configure(tb->root_switch);
	if (ret) {
		tb_switch_put(tb->root_switch);
		return ret;
	}

	/* Announce the switch to the world */
	ret = tb_switch_add(tb->root_switch);
	if (ret) {
		tb_switch_put(tb->root_switch);
		return ret;
	}

	/* Full scan to discover devices added before the driver was loaded. */
	tb_scan_switch(tb->root_switch);
	/* Find out tunnels created by the boot firmware */
	tb_discover_tunnels(tb->root_switch);
	/* Make the discovered switches available to the userspace */
	device_for_each_child(&tb->root_switch->dev, NULL,
			      tb_scan_finalize_switch);

	/* Allow tb_handle_hotplug to progress events */
	tcm->hotplug_active = true;
	return 0;
}

static int tb_suspend_noirq(struct tb *tb)
{
	struct tb_cm *tcm = tb_priv(tb);

	tb_dbg(tb, "suspending...\n");
	tb_switch_suspend(tb->root_switch);
	tcm->hotplug_active = false; /* signal tb_handle_hotplug to quit */
	tb_dbg(tb, "suspend finished\n");

	return 0;
}

static int tb_resume_noirq(struct tb *tb)
{
	struct tb_cm *tcm = tb_priv(tb);
	struct tb_tunnel *tunnel, *n;

	tb_dbg(tb, "resuming...\n");

	/* remove any pci devices the firmware might have setup */
	tb_switch_reset(tb, 0);

	tb_switch_resume(tb->root_switch);
	tb_free_invalid_tunnels(tb);
	tb_free_unplugged_children(tb->root_switch);
	list_for_each_entry_safe(tunnel, n, &tcm->tunnel_list, list)
		tb_tunnel_restart(tunnel);
	if (!list_empty(&tcm->tunnel_list)) {
		/*
		 * the pcie links need some time to get going.
		 * 100ms works for me...
		 */
		tb_dbg(tb, "tunnels restarted, sleeping for 100ms\n");
		msleep(100);
	}
	 /* Allow tb_handle_hotplug to progress events */
	tcm->hotplug_active = true;
	tb_dbg(tb, "resume finished\n");

	return 0;
}

static const struct tb_cm_ops tb_cm_ops = {
	.start = tb_start,
	.stop = tb_stop,
	.suspend_noirq = tb_suspend_noirq,
	.resume_noirq = tb_resume_noirq,
	.handle_event = tb_handle_event,
	.approve_switch = tb_tunnel_pci,
};

struct tb *tb_probe(struct tb_nhi *nhi)
{
	struct tb_cm *tcm;
	struct tb *tb;

	if (!x86_apple_machine)
		return NULL;

	tb = tb_domain_alloc(nhi, sizeof(*tcm));
	if (!tb)
		return NULL;

	tb->security_level = TB_SECURITY_USER;
	tb->cm_ops = &tb_cm_ops;

	tcm = tb_priv(tb);
	INIT_LIST_HEAD(&tcm->tunnel_list);

	return tb;
}