path: root/drivers/thunderbolt/tunnel.c

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

#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/list.h>

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

/* PCIe adapters use always HopID of 8 for both directions */
#define TB_PCI_HOPID			8

#define TB_PCI_PATH_DOWN		0
#define TB_PCI_PATH_UP			1

/* USB3 adapters use always HopID of 8 for both directions */
#define TB_USB3_HOPID			8

#define TB_USB3_PATH_DOWN		0
#define TB_USB3_PATH_UP			1

/* DP adapters use HopID 8 for AUX and 9 for Video */
#define TB_DP_AUX_TX_HOPID		8
#define TB_DP_AUX_RX_HOPID		8
#define TB_DP_VIDEO_HOPID		9

#define TB_DP_VIDEO_PATH_OUT		0
#define TB_DP_AUX_PATH_OUT		1
#define TB_DP_AUX_PATH_IN		2

static const char * const tb_tunnel_names[] = { "PCI", "DP", "DMA", "USB3" };

#define __TB_TUNNEL_PRINT(level, tunnel, fmt, arg...)                   \
	do {                                                            \
		struct tb_tunnel *__tunnel = (tunnel);                  \
		level(__tunnel->tb, "%llx:%x <-> %llx:%x (%s): " fmt,   \
		      tb_route(__tunnel->src_port->sw),                 \
		      __tunnel->src_port->port,                         \
		      tb_route(__tunnel->dst_port->sw),                 \
		      __tunnel->dst_port->port,                         \
		      tb_tunnel_names[__tunnel->type],			\
		      ## arg);                                          \
	} while (0)

#define tb_tunnel_WARN(tunnel, fmt, arg...) \
	__TB_TUNNEL_PRINT(tb_WARN, tunnel, fmt, ##arg)
#define tb_tunnel_warn(tunnel, fmt, arg...) \
	__TB_TUNNEL_PRINT(tb_warn, tunnel, fmt, ##arg)
#define tb_tunnel_info(tunnel, fmt, arg...) \
	__TB_TUNNEL_PRINT(tb_info, tunnel, fmt, ##arg)
#define tb_tunnel_dbg(tunnel, fmt, arg...) \
	__TB_TUNNEL_PRINT(tb_dbg, tunnel, fmt, ##arg)

static struct tb_tunnel *tb_tunnel_alloc(struct tb *tb, size_t npaths,
					 enum tb_tunnel_type type)
{
	struct tb_tunnel *tunnel;

	tunnel = kzalloc(sizeof(*tunnel), GFP_KERNEL);
	if (!tunnel)
		return NULL;

	tunnel->paths = kcalloc(npaths, sizeof(tunnel->paths[0]), GFP_KERNEL);
	if (!tunnel->paths) {
		tb_tunnel_free(tunnel);
		return NULL;
	}

	INIT_LIST_HEAD(&tunnel->list);
	tunnel->tb = tb;
	tunnel->npaths = npaths;
	tunnel->type = type;

	return tunnel;
}

static int tb_pci_activate(struct tb_tunnel *tunnel, bool activate)
{
	int res;

	res = tb_pci_port_enable(tunnel->src_port, activate);
	if (res)
		return res;

	if (tb_port_is_pcie_up(tunnel->dst_port))
		return tb_pci_port_enable(tunnel->dst_port, activate);

	return 0;
}

static int tb_initial_credits(const struct tb_switch *sw)
{
	/* If the path is complete sw is not NULL */
	if (sw) {
		/* More credits for faster link */
		switch (sw->link_speed * sw->link_width) {
		case 40:
			return 32;
		case 20:
			return 24;
		}
	}

	return 16;
}

static void tb_pci_init_path(struct tb_path *path)
{
	path->egress_fc_enable = TB_PATH_SOURCE | TB_PATH_INTERNAL;
	path->egress_shared_buffer = TB_PATH_NONE;
	path->ingress_fc_enable = TB_PATH_ALL;
	path->ingress_shared_buffer = TB_PATH_NONE;
	path->priority = 3;
	path->weight = 1;
	path->drop_packages = 0;
	path->nfc_credits = 0;
	path->hops[0].initial_credits = 7;
	if (path->path_length > 1)
		path->hops[1].initial_credits =
			tb_initial_credits(path->hops[1].in_port->sw);
}

/**
 * tb_tunnel_discover_pci() - Discover existing PCIe tunnels
 * @tb: Pointer to the domain structure
 * @down: PCIe downstream adapter
 *
 * If @down adapter is active, follows the tunnel to the PCIe upstream
 * adapter and back. Returns the discovered tunnel or %NULL if there was
 * no tunnel.
 */
struct tb_tunnel *tb_tunnel_discover_pci(struct tb *tb, struct tb_port *down)
{
	struct tb_tunnel *tunnel;
	struct tb_path *path;

	if (!tb_pci_port_is_enabled(down))
		return NULL;

	tunnel = tb_tunnel_alloc(tb, 2, TB_TUNNEL_PCI);
	if (!tunnel)
		return NULL;

	tunnel->activate = tb_pci_activate;
	tunnel->src_port = down;

	/*
	 * Discover both paths even if they are not complete. We will
	 * clean them up by calling tb_tunnel_deactivate() below in that
	 * case.
	 */
	path = tb_path_discover(down, TB_PCI_HOPID, NULL, -1,
				&tunnel->dst_port, "PCIe Up");
	if (!path) {
		/* Just disable the downstream port */
		tb_pci_port_enable(down, false);
		goto err_free;
	}
	tunnel->paths[TB_PCI_PATH_UP] = path;
	tb_pci_init_path(tunnel->paths[TB_PCI_PATH_UP]);

	path = tb_path_discover(tunnel->dst_port, -1, down, TB_PCI_HOPID, NULL,
				"PCIe Down");
	if (!path)
		goto err_deactivate;
	tunnel->paths[TB_PCI_PATH_DOWN] = path;
	tb_pci_init_path(tunnel->paths[TB_PCI_PATH_DOWN]);

	/* Validate that the tunnel is complete */
	if (!tb_port_is_pcie_up(tunnel->dst_port)) {
		tb_port_warn(tunnel->dst_port,
			     "path does not end on a PCIe adapter, cleaning up\n");
		goto err_deactivate;
	}

	if (down != tunnel->src_port) {
		tb_tunnel_warn(tunnel, "path is not complete, cleaning up\n");
		goto err_deactivate;
	}

	if (!tb_pci_port_is_enabled(tunnel->dst_port)) {
		tb_tunnel_warn(tunnel,
			       "tunnel is not fully activated, cleaning up\n");
		goto err_deactivate;
	}

	tb_tunnel_dbg(tunnel, "discovered\n");
	return tunnel;

err_deactivate:
	tb_tunnel_deactivate(tunnel);
err_free:
	tb_tunnel_free(tunnel);

	return NULL;
}

/**
 * tb_tunnel_alloc_pci() - allocate a pci tunnel
 * @tb: Pointer to the domain structure
 * @up: PCIe upstream adapter port
 * @down: PCIe downstream adapter port
 *
 * Allocate a PCI tunnel. The ports must be of type TB_TYPE_PCIE_UP and
 * TB_TYPE_PCIE_DOWN.
 *
 * Return: Returns a tb_tunnel on success or NULL on failure.
 */
struct tb_tunnel *tb_tunnel_alloc_pci(struct tb *tb, struct tb_port *up,
				      struct tb_port *down)
{
	struct tb_tunnel *tunnel;
	struct tb_path *path;

	tunnel = tb_tunnel_alloc(tb, 2, TB_TUNNEL_PCI);
	if (!tunnel)
		return NULL;

	tunnel->activate = tb_pci_activate;
	tunnel->src_port = down;
	tunnel->dst_port = up;

	path = tb_path_alloc(tb, down, TB_PCI_HOPID, up, TB_PCI_HOPID, 0,
			     "PCIe Down");
	if (!path) {
		tb_tunnel_free(tunnel);
		return NULL;
	}
	tb_pci_init_path(path);
	tunnel->paths[TB_PCI_PATH_DOWN] = path;

	path = tb_path_alloc(tb, up, TB_PCI_HOPID, down, TB_PCI_HOPID, 0,
			     "PCIe Up");
	if (!path) {
		tb_tunnel_free(tunnel);
		return NULL;
	}
	tb_pci_init_path(path);
	tunnel->paths[TB_PCI_PATH_UP] = path;

	return tunnel;
}

static bool tb_dp_is_usb4(const struct tb_switch *sw)
{
	/* Titan Ridge DP adapters need the same treatment as USB4 */
	return tb_switch_is_usb4(sw) || tb_switch_is_titan_ridge(sw);
}

static int tb_dp_cm_handshake(struct tb_port *in, struct tb_port *out)
{
	int timeout = 10;
	u32 val;
	int ret;

	/* Both ends need to support this */
	if (!tb_dp_is_usb4(in->sw) || !tb_dp_is_usb4(out->sw))
		return 0;

	ret = tb_port_read(out, &val, TB_CFG_PORT,
			   out->cap_adap + DP_STATUS_CTRL, 1);
	if (ret)
		return ret;

	val |= DP_STATUS_CTRL_UF | DP_STATUS_CTRL_CMHS;

	ret = tb_port_write(out, &val, TB_CFG_PORT,
			    out->cap_adap + DP_STATUS_CTRL, 1);
	if (ret)
		return ret;

	do {
		ret = tb_port_read(out, &val, TB_CFG_PORT,
				   out->cap_adap + DP_STATUS_CTRL, 1);
		if (ret)
			return ret;
		if (!(val & DP_STATUS_CTRL_CMHS))
			return 0;
		usleep_range(10, 100);
	} while (timeout--);

	return -ETIMEDOUT;
}

static inline u32 tb_dp_cap_get_rate(u32 val)
{
	u32 rate = (val & DP_COMMON_CAP_RATE_MASK) >> DP_COMMON_CAP_RATE_SHIFT;

	switch (rate) {
	case DP_COMMON_CAP_RATE_RBR:
		return 1620;
	case DP_COMMON_CAP_RATE_HBR:
		return 2700;
	case DP_COMMON_CAP_RAT