Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 717 insertions, 0 deletions

diff --git a/drivers/thunderbolt/lc.c b/drivers/thunderbolt/lc.c
new file mode 100644
index 000000000..4449c28cc
--- /dev/null
+++ b/drivers/thunderbolt/lc.c
@@ -0,0 +1,717 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Thunderbolt link controller support
+ *
+ * Copyright (C) 2019, Intel Corporation
+ * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
+ */
+
+#include <linux/delay.h>
+
+#include "tb.h"
+
+/**
+ * tb_lc_read_uuid() - Read switch UUID from link controller common register
+ * @sw: Switch whose UUID is read
+ * @uuid: UUID is placed here
+ *
+ * Return: %0 on success, negative errno otherwise.
+ */
+int tb_lc_read_uuid(struct tb_switch *sw, u32 *uuid)
+{
+	if (!sw->cap_lc)
+		return -EINVAL;
+	return tb_sw_read(sw, uuid, TB_CFG_SWITCH, sw->cap_lc + TB_LC_FUSE, 4);
+}
+
+static int read_lc_desc(struct tb_switch *sw, u32 *desc)
+{
+	if (!sw->cap_lc)
+		return -EINVAL;
+	return tb_sw_read(sw, desc, TB_CFG_SWITCH, sw->cap_lc + TB_LC_DESC, 1);
+}
+
+static int find_port_lc_cap(struct tb_port *port)
+{
+	struct tb_switch *sw = port->sw;
+	int start, phys, ret, size;
+	u32 desc;
+
+	ret = read_lc_desc(sw, &desc);
+	if (ret)
+		return ret;
+
+	/* Start of port LC registers */
+	start = (desc & TB_LC_DESC_SIZE_MASK) >> TB_LC_DESC_SIZE_SHIFT;
+	size = (desc & TB_LC_DESC_PORT_SIZE_MASK) >> TB_LC_DESC_PORT_SIZE_SHIFT;
+	phys = tb_phy_port_from_link(port->port);
+
+	return sw->cap_lc + start + phys * size;
+}
+
+/**
+ * tb_lc_reset_port() - Trigger downstream port reset through LC
+ * @port: Port that is reset
+ *
+ * Triggers downstream port reset through link controller registers.
+ * Only supports non-USB4 routers with link controller (that's
+ * Thunderbolt 2 and Thunderbolt 3).
+ *
+ * Return: %0 on success, negative errno otherwise.
+ */
+int tb_lc_reset_port(struct tb_port *port)
+{
+	struct tb_switch *sw = port->sw;
+	int cap, ret;
+	u32 mode;
+
+	if (sw->generation < 2)
+		return -EINVAL;
+
+	cap = find_port_lc_cap(port);
+	if (cap < 0)
+		return cap;
+
+	ret = tb_sw_read(sw, &mode, TB_CFG_SWITCH, cap + TB_LC_PORT_MODE, 1);
+	if (ret)
+		return ret;
+
+	mode |= TB_LC_PORT_MODE_DPR;
+
+	ret = tb_sw_write(sw, &mode, TB_CFG_SWITCH, cap + TB_LC_PORT_MODE, 1);
+	if (ret)
+		return ret;
+
+	fsleep(10000);
+
+	ret = tb_sw_read(sw, &mode, TB_CFG_SWITCH, cap + TB_LC_PORT_MODE, 1);
+	if (ret)
+		return ret;
+
+	mode &= ~TB_LC_PORT_MODE_DPR;
+
+	return tb_sw_write(sw, &mode, TB_CFG_SWITCH, cap + TB_LC_PORT_MODE, 1);
+}
+
+static int tb_lc_set_port_configured(struct tb_port *port, bool configured)
+{
+	bool upstream = tb_is_upstream_port(port);
+	struct tb_switch *sw = port->sw;
+	u32 ctrl, lane;
+	int cap, ret;
+
+	if (sw->generation < 2)
+		return 0;
+
+	cap = find_port_lc_cap(port);
+	if (cap < 0)
+		return cap;
+
+	ret = tb_sw_read(sw, &ctrl, TB_CFG_SWITCH, cap + TB_LC_SX_CTRL, 1);
+	if (ret)
+		return ret;
+
+	/* Resolve correct lane */
+	if (port->port % 2)
+		lane = TB_LC_SX_CTRL_L1C;
+	else
+		lane = TB_LC_SX_CTRL_L2C;
+
+	if (configured) {
+		ctrl |= lane;
+		if (upstream)
+			ctrl |= TB_LC_SX_CTRL_UPSTREAM;
+	} else {
+		ctrl &= ~lane;
+		if (upstream)
+			ctrl &= ~TB_LC_SX_CTRL_UPSTREAM;
+	}
+
+	return tb_sw_write(sw, &ctrl, TB_CFG_SWITCH, cap + TB_LC_SX_CTRL, 1);
+}
+
+/**
+ * tb_lc_configure_port() - Let LC know about configured port
+ * @port: Port that is set as configured
+ *
+ * Sets the port configured for power management purposes.
+ *
+ * Return: %0 on success, negative errno otherwise.
+ */
+int tb_lc_configure_port(struct tb_port *port)
+{
+	return tb_lc_set_port_configured(port, true);
+}
+
+/**
+ * tb_lc_unconfigure_port() - Let LC know about unconfigured port
+ * @port: Port that is set as configured
+ *
+ * Sets the port unconfigured for power management purposes.
+ *
+ * Return: %0 on success, negative errno otherwise.
+ */
+void tb_lc_unconfigure_port(struct tb_port *port)
+{
+	tb_lc_set_port_configured(port, false);
+}
+
+static int tb_lc_set_xdomain_configured(struct tb_port *port, bool configure)
+{
+	struct tb_switch *sw = port->sw;
+	u32 ctrl, lane;
+	int cap, ret;
+
+	if (sw->generation < 2)
+		return 0;
+
+	cap = find_port_lc_cap(port);
+	if (cap < 0)
+		return cap;
+
+	ret = tb_sw_read(sw, &ctrl, TB_CFG_SWITCH, cap + TB_LC_SX_CTRL, 1);
+	if (ret)
+		return ret;
+
+	/* Resolve correct lane */
+	if (port->port % 2)
+		lane = TB_LC_SX_CTRL_L1D;
+	else
+		lane = TB_LC_SX_CTRL_L2D;
+
+	if (configure)
+		ctrl |= lane;
+	else
+		ctrl &= ~lane;
+
+	return tb_sw_write(sw, &ctrl, TB_CFG_SWITCH, cap + TB_LC_SX_CTRL, 1);
+}
+
+/**
+ * tb_lc_configure_xdomain() - Inform LC that the link is XDomain
+ * @port: Switch downstream port connected to another host
+ *
+ * Sets the lane configured for XDomain accordingly so that LC knows
+ * about this.
+ *
+ * Return: %0 on success, negative errno otherwise.
+ */
+int tb_lc_configure_xdomain(struct tb_port *port)
+{
+	return tb_lc_set_xdomain_configured(port, true);
+}
+
+/**
+ * tb_lc_unconfigure_xdomain() - Unconfigure XDomain from port
+ * @port: Switch downstream port that was connected to another host
+ *
+ * Unsets the lane XDomain configuration.
+ */
+void tb_lc_unconfigure_xdomain(struct tb_port *port)
+{
+	tb_lc_set_xdomain_configured(port, false);
+}
+
+/**
+ * tb_lc_start_lane_initialization() - Start lane initialization
+ * @port: Device router lane 0 adapter
+ *
+ * Starts lane initialization for @port after the router resumed from
+ * sleep. Should be called for those downstream lane adapters that were
+ * not connected (tb_lc_configure_port() was not called) before sleep.
+ *
+ * Return: %0 on success, negative errno otherwise.
+ */
+int tb_lc_start_lane_initialization(struct tb_port *port)
+{
+	struct tb_switch *sw = port->sw;
+	int ret, cap;
+	u32 ctrl;
+
+	if (!tb_route(sw))
+		return 0;
+
+	if (sw->generation < 2)
+		return 0;
+
+	cap = find_port_lc_cap(port);
+	if (cap < 0)
+		return cap;
+
+	ret = tb_sw_read(sw, &ctrl, TB_CFG_SWITCH, cap + TB_LC_SX_CTRL, 1);
+	if (ret)
+		return ret;
+
+	ctrl |= TB_LC_SX_CTRL_SLI;
+
+	return tb_sw_write(sw, &ctrl, TB_CFG_SWITCH, cap + TB_LC_SX_CTRL, 1);
+}
+
+/**
+ * tb_lc_is_clx_supported() - Check whether CLx is supported by the lane adapter
+ * @port: Lane adapter
+ *
+ * TB_LC_LINK_ATTR_CPS bit reflects if the link supports CLx including
+ * active cables (if connected on the link).
+ *
+ * Return: %true if CLx is supported, %false otherwise.
+ */
+bool tb_lc_is_clx_supported(struct tb_port *port)
+{
+	struct tb_switch *sw = port->sw;
+	int cap, ret;
+	u32 val;
+
+	cap = find_port_lc_cap(port);
+	if (cap < 0)
+		return false;
+
+	ret = tb_sw_read(sw, &val, TB_CFG_SWITCH, cap + TB_LC_LINK_ATTR, 1);
+	if (ret)
+		return false;
+
+	return !!(val & TB_LC_LINK_ATTR_CPS);
+}
+
+/**
+ * tb_lc_is_usb_plugged() - Is there USB device connected to port
+ * @port: Device router lane 0 adapter
+ *
+ * Return: %true if the @port has USB Type-C device connected, %false
+ * otherwise.
+ */
+bool tb_lc_is_usb_plugged(struct tb_port *port)
+{
+	struct tb_switch *sw = port->sw;
+	int cap, ret;
+	u32 val;
+
+	if (sw->generation != 3)
+		return false;
+
+	cap = find_port_lc_cap(port);
+	if (cap < 0)
+		return false;
+
+	ret = tb_sw_read(sw, &val, TB_CFG_SWITCH, cap + TB_LC_CS_42, 1);
+	if (ret)
+		return false;
+
+	return !!(val & TB_LC_CS_42_USB_PLUGGED);
+}
+
+/**
+ * tb_lc_is_xhci_connected() - Is the internal xHCI connected
+ * @port: Device router lane 0 adapter
+ *
+ * Return: %true if the internal xHCI has been connected to
+ * @port, %false otherwise.
+ */
+bool tb_lc_is_xhci_connected(struct tb_port *port)
+{
+	struct tb_switch *sw = port->sw;
+	int cap, ret;
+	u32 val;
+
+	if (sw->generation != 3)
+		return false;
+
+	cap = find_port_lc_cap(port);
+	if (cap < 0)
+		return false;
+
+	ret = tb_sw_read(sw, &val, TB_CFG_SWITCH, cap + TB_LC_LINK_REQ, 1);
+	if (ret)
+		return false;
+
+	return !!(val & TB_LC_LINK_REQ_XHCI_CONNECT);
+}
+
+static int __tb_lc_xhci_connect(struct tb_port *port, bool connect)
+{
+	struct tb_switch *sw = port->sw;
+	int cap, ret;
+	u32 val;
+
+	if (sw->generation != 3)
+		return -EINVAL;
+
+	cap = find_port_lc_cap(port);
+	if (cap < 0)
+		return cap;
+
+	ret = tb_sw_read(sw, &val, TB_CFG_SWITCH, cap + TB_LC_LINK_REQ, 1);
+	if (ret)
+		return ret;
+
+	if (connect)
+		val |= TB_LC_LINK_REQ_XHCI_CONNECT;
+	else
+		val &= ~TB_LC_LINK_REQ_XHCI_CONNECT;
+
+	return tb_sw_write(sw, &val, TB_CFG_SWITCH, cap + TB_LC_LINK_REQ, 1);
+}
+
+/**
+ * tb_lc_xhci_connect() - Connect internal xHCI
+ * @port: Device router lane 0 adapter
+ *
+ * Tells LC to connect the internal xHCI to @port. Can be called for
+ * Thunderbolt 3 routers only.
+ *
+ * Return: %0 on success, negative errno otherwise.
+ */
+int tb_lc_xhci_connect(struct tb_port *port)
+{
+	int ret;
+
+	ret = __tb_lc_xhci_connect(port, true);
+	if (ret)
+		return ret;
+
+	tb_port_dbg(port, "xHCI connected\n");
+	return 0;
+}
+
+/**
+ * tb_lc_xhci_disconnect() - Disconnect internal xHCI
+ * @port: Device router lane 0 adapter
+ *
+ * Tells LC to disconnect the internal xHCI from @port. Can be called
+ * for Thunderbolt 3 routers only.
+ */
+void tb_lc_xhci_disconnect(struct tb_port *port)
+{
+	__tb_lc_xhci_connect(port, false);
+	tb_port_dbg(port, "xHCI disconnected\n");
+}
+
+static int tb_lc_set_wake_one(struct tb_switch *sw, unsigned int offset,
+			      unsigned int flags)
+{
+	u32 ctrl;
+	int ret;
+
+	/*
+	 * Enable wake on PCIe and USB4 (wake coming from another
+	 * router).
+	 */
+	ret = tb_sw_read(sw, &ctrl, TB_CFG_SWITCH,
+			 offset + TB_LC_SX_CTRL, 1);
+	if (ret)
+		return ret;
+
+	ctrl &= ~(TB_LC_SX_CTRL_WOC | TB_LC_SX_CTRL_WOD | TB_LC_SX_CTRL_WODPC |
+		  TB_LC_SX_CTRL_WODPD | TB_LC_SX_CTRL_WOP | TB_LC_SX_CTRL_WOU4);
+
+	if (flags & TB_WAKE_ON_CONNECT)
+		ctrl |= TB_LC_SX_CTRL_WOC | TB_LC_SX_CTRL_WOD;
+	if (flags & TB_WAKE_ON_USB4)
+		ctrl |= TB_LC_SX_CTRL_WOU4;
+	if (flags & TB_WAKE_ON_PCIE)
+		ctrl |= TB_LC_SX_CTRL_WOP;
+	if (flags & TB_WAKE_ON_DP)
+		ctrl |= TB_LC_SX_CTRL_WODPC | TB_LC_SX_CTRL_WODPD;
+
+	return tb_sw_write(sw, &ctrl, TB_CFG_SWITCH, offset + TB_LC_SX_CTRL, 1);
+}
+
+/**
+ * tb_lc_set_wake() - Enable/disable wake
+ * @sw: Switch whose wakes to configure
+ * @flags: Wakeup flags (%0 to disable)
+ *
+ * For each LC sets wake bits accordingly.
+ *
+ * Return: %0 on success, negative errno otherwise.
+ */
+int tb_lc_set_wake(struct tb_switch *sw, unsigned int flags)
+{
+	int start, size, nlc, ret, i;
+	u32 desc;
+
+	if (sw->generation < 2)
+		return 0;
+
+	if (!tb_route(sw))
+		return 0;
+
+	ret = read_lc_desc(sw, &desc);
+	if (ret)
+		return ret;
+
+	/* Figure out number of link controllers */
+	nlc = desc & TB_LC_DESC_NLC_MASK;
+	start = (desc & TB_LC_DESC_SIZE_MASK) >> TB_LC_DESC_SIZE_SHIFT;
+	size = (desc & TB_LC_DESC_PORT_SIZE_MASK) >> TB_LC_DESC_PORT_SIZE_SHIFT;
+
+	/* For each link controller set sleep bit */
+	for (i = 0; i < nlc; i++) {
+		unsigned int offset = sw->cap_lc + start + i * size;
+
+		ret = tb_lc_set_wake_one(sw, offset, flags);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+/**
+ * tb_lc_set_sleep() - Inform LC that the switch is going to sleep
+ * @sw: Switch to set sleep
+ *
+ * Let the switch link controllers know that the switch is going to
+ * sleep.
+ *
+ * Return: %0 on success, negative errno otherwise.
+ */
+int tb_lc_set_sleep(struct tb_switch *sw)
+{
+	int start, size, nlc, ret, i;
+	u32 desc;
+
+	if (sw->generation < 2)
+		return 0;
+
+	ret = read_lc_desc(sw, &desc);
+	if (ret)
+		return ret;
+
+	/* Figure out number of link controllers */
+	nlc = desc & TB_LC_DESC_NLC_MASK;
+	start = (desc & TB_LC_DESC_SIZE_MASK) >> TB_LC_DESC_SIZE_SHIFT;
+	size = (desc & TB_LC_DESC_PORT_SIZE_MASK) >> TB_LC_DESC_PORT_SIZE_SHIFT;
+
+	/* For each link controller set sleep bit */
+	for (i = 0; i < nlc; i++) {
+		unsigned int offset = sw->cap_lc + start + i * size;
+		u32 ctrl;
+
+		ret = tb_sw_read(sw, &ctrl, TB_CFG_SWITCH,
+				 offset + TB_LC_SX_CTRL, 1);
+		if (ret)
+			return ret;
+
+		ctrl |= TB_LC_SX_CTRL_SLP;
+		ret = tb_sw_write(sw, &ctrl, TB_CFG_SWITCH,
+				  offset + TB_LC_SX_CTRL, 1);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+/**
+ * tb_lc_lane_bonding_possible() - Is lane bonding possible towards switch
+ * @sw: Switch to check
+ *
+ * Checks whether conditions for lane bonding from parent to @sw are
+ * possible.
+ *
+ * Return: %true if lane bonding is possible, %false otherwise.
+ */
+bool tb_lc_lane_bonding_possible(struct tb_switch *sw)
+{
+	struct tb_port *up;
+	int cap, ret;
+	u32 val;
+
+	if (sw->generation < 2)
+		return false;
+
+	up = tb_upstream_port(sw);
+	cap = find_port_lc_cap(up);
+	if (cap < 0)
+		return false;
+
+	ret = tb_sw_read(sw, &val, TB_CFG_SWITCH, cap + TB_LC_PORT_ATTR, 1);
+	if (ret)
+		return false;
+
+	return !!(val & TB_LC_PORT_ATTR_BE);
+}
+
+static int tb_lc_dp_sink_from_port(const struct tb_switch *sw,
+				   struct tb_port *in)
+{
+	struct tb_port *port;
+
+	/* The first DP IN port is sink 0 and second is sink 1 */
+	tb_switch_for_each_port(sw, port) {
+		if (tb_port_is_dpin(port))
+			return in != port;
+	}
+
+	return -EINVAL;
+}
+
+static int tb_lc_dp_sink_available(struct tb_switch *sw, int sink)
+{
+	u32 val, alloc;
+	int ret;
+
+	ret = tb_sw_read(sw, &val, TB_CFG_SWITCH,
+			 sw->cap_lc + TB_LC_SNK_ALLOCATION, 1);
+	if (ret)
+		return ret;
+
+	/*
+	 * Sink is available for CM/SW to use if the allocation value is
+	 * either 0 or 1.
+	 */
+	if (!sink) {
+		alloc = val & TB_LC_SNK_ALLOCATION_SNK0_MASK;
+		if (!alloc || alloc == TB_LC_SNK_ALLOCATION_SNK0_CM)
+			return 0;
+	} else {
+		alloc = (val & TB_LC_SNK_ALLOCATION_SNK1_MASK) >>
+			TB_LC_SNK_ALLOCATION_SNK1_SHIFT;
+		if (!alloc || alloc == TB_LC_SNK_ALLOCATION_SNK1_CM)
+			return 0;
+	}
+
+	return -EBUSY;
+}
+
+/**
+ * tb_lc_dp_sink_query() - Is DP sink available for DP IN port
+ * @sw: Switch whose DP sink is queried
+ * @in: DP IN port to check
+ *
+ * Queries through LC SNK_ALLOCATION registers whether DP sink is available
+ * for the given DP IN port or not.
+ *
+ * Return: %true if DP sink is available, %false otherwise.
+ */
+bool tb_lc_dp_sink_query(struct tb_switch *sw, struct tb_port *in)
+{
+	int sink;
+
+	/*
+	 * For older generations sink is always available as there is no
+	 * allocation mechanism.
+	 */
+	if (sw->generation < 3)
+		return true;
+
+	sink = tb_lc_dp_sink_from_port(sw, in);
+	if (sink < 0)
+		return false;
+
+	return !tb_lc_dp_sink_available(sw, sink);
+}
+
+/**
+ * tb_lc_dp_sink_alloc() - Allocate DP sink
+ * @sw: Switch whose DP sink is allocated
+ * @in: DP IN port the DP sink is allocated for
+ *
+ * Allocate DP sink for @in via LC SNK_ALLOCATION registers.
+ *
+ * Return:
+ * * %0 - If the resource is available and allocation is successful.
+ * * %-EBUSY - If resource is not available.
+ * * Negative errno - Another error occurred.
+ */
+int tb_lc_dp_sink_alloc(struct tb_switch *sw, struct tb_port *in)
+{
+	int ret, sink;
+	u32 val;
+
+	if (sw->generation < 3)
+		return 0;
+
+	sink = tb_lc_dp_sink_from_port(sw, in);
+	if (sink < 0)
+		return sink;
+
+	ret = tb_lc_dp_sink_available(sw, sink);
+	if (ret)
+		return ret;
+
+	ret = tb_sw_read(sw, &val, TB_CFG_SWITCH,
+			 sw->cap_lc + TB_LC_SNK_ALLOCATION, 1);
+	if (ret)
+		return ret;
+
+	if (!sink) {
+		val &= ~TB_LC_SNK_ALLOCATION_SNK0_MASK;
+		val |= TB_LC_SNK_ALLOCATION_SNK0_CM;
+	} else {
+		val &= ~TB_LC_SNK_ALLOCATION_SNK1_MASK;
+		val |= TB_LC_SNK_ALLOCATION_SNK1_CM <<
+			TB_LC_SNK_ALLOCATION_SNK1_SHIFT;
+	}
+
+	ret = tb_sw_write(sw, &val, TB_CFG_SWITCH,
+			  sw->cap_lc + TB_LC_SNK_ALLOCATION, 1);
+
+	if (ret)
+		return ret;
+
+	tb_port_dbg(in, "sink %d allocated\n", sink);
+	return 0;
+}
+
+/**
+ * tb_lc_dp_sink_dealloc() - De-allocate DP sink
+ * @sw: Switch whose DP sink is de-allocated
+ * @in: DP IN port whose DP sink is de-allocated
+ *
+ * De-allocate DP sink from @in using LC SNK_ALLOCATION registers.
+ *
+ * Return: %0 on success, negative errno otherwise.
+ */
+int tb_lc_dp_sink_dealloc(struct tb_switch *sw, struct tb_port *in)
+{
+	int ret, sink;
+	u32 val;
+
+	if (sw->generation < 3)
+		return 0;
+
+	sink = tb_lc_dp_sink_from_port(sw, in);
+	if (sink < 0)
+		return sink;
+
+	/* Needs to be owned by CM/SW */
+	ret = tb_lc_dp_sink_available(sw, sink);
+	if (ret)
+		return ret;
+
+	ret = tb_sw_read(sw, &val, TB_CFG_SWITCH,
+			 sw->cap_lc + TB_LC_SNK_ALLOCATION, 1);
+	if (ret)
+		return ret;
+
+	if (!sink)
+		val &= ~TB_LC_SNK_ALLOCATION_SNK0_MASK;
+	else
+		val &= ~TB_LC_SNK_ALLOCATION_SNK1_MASK;
+
+	ret = tb_sw_write(sw, &val, TB_CFG_SWITCH,
+			  sw->cap_lc + TB_LC_SNK_ALLOCATION, 1);
+	if (ret)
+		return ret;
+
+	tb_port_dbg(in, "sink %d de-allocated\n", sink);
+	return 0;
+}
+
+/**
+ * tb_lc_force_power() - Forces LC to be powered on
+ * @sw: Thunderbolt switch
+ *
+ * This is useful to let authentication cycle pass even without
+ * a Thunderbolt link present.
+ *
+ * Return: %0 on success, negative errno otherwise.
+ */
+int tb_lc_force_power(struct tb_switch *sw)
+{
+	u32 in = 0xffff;
+
+	return tb_sw_write(sw, &in, TB_CFG_SWITCH, TB_LC_POWER, 1);
+}