thunderbolt: Add support for Time Management Unit

Time Management Unit (TMU) is included in each USB4 router. It is used
to synchronize time across the USB4 fabric. By default when USB4 router
is plugged to the domain, its TMU is turned off. This differs from
Thunderbolt (1, 2 and 3) devices whose TMU is by default configured to
bi-directional HiFi mode. Since time synchronization is needed for
proper Display Port tunneling this means we need to configure the TMU on
USB4 compliant devices.

The USB4 spec allows some flexibility on how the TMU can be configured.
This makes it possible to enable link power management states (CLx) in
certain topologies, where for example DP tunneling is not used. TMU can
also be re-configured dynamicaly depending on types of tunnels created
over the USB4 fabric.

In this patch we simply configure the TMU to be in bi-directional HiFi
mode. This way we can tunnel any kind of traffic without need to perform
complex steps to re-configure the domain dynamically. We can add more
fine-grained TMU configuration later on when we start enabling CLx
states.

Signed-off-by: Rajmohan Mani <rajmohan.mani@intel.com>
Co-developed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Link: https://lore.kernel.org/r/20191217123345.31850-8-mika.westerberg@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 383 insertions, 0 deletions

diff --git a/drivers/thunderbolt/tmu.c b/drivers/thunderbolt/tmu.c
new file mode 100644
index 000000000000..039c42a06000
--- /dev/null
+++ b/drivers/thunderbolt/tmu.c
@@ -0,0 +1,383 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Thunderbolt Time Management Unit (TMU) support
+ *
+ * Copyright (C) 2019, Intel Corporation
+ * Authors: Mika Westerberg <mika.westerberg@linux.intel.com>
+ *	    Rajmohan Mani <rajmohan.mani@intel.com>
+ */
+
+#include <linux/delay.h>
+
+#include "tb.h"
+
+static const char *tb_switch_tmu_mode_name(const struct tb_switch *sw)
+{
+	bool root_switch = !tb_route(sw);
+
+	switch (sw->tmu.rate) {
+	case TB_SWITCH_TMU_RATE_OFF:
+		return "off";
+
+	case TB_SWITCH_TMU_RATE_HIFI:
+		/* Root switch does not have upstream directionality */
+		if (root_switch)
+			return "HiFi";
+		if (sw->tmu.unidirectional)
+			return "uni-directional, HiFi";
+		return "bi-directional, HiFi";
+
+	case TB_SWITCH_TMU_RATE_NORMAL:
+		if (root_switch)
+			return "normal";
+		return "uni-directional, normal";
+
+	default:
+		return "unknown";
+	}
+}
+
+static bool tb_switch_tmu_ucap_supported(struct tb_switch *sw)
+{
+	int ret;
+	u32 val;
+
+	ret = tb_sw_read(sw, &val, TB_CFG_SWITCH,
+			 sw->tmu.cap + TMU_RTR_CS_0, 1);
+	if (ret)
+		return false;
+
+	return !!(val & TMU_RTR_CS_0_UCAP);
+}
+
+static int tb_switch_tmu_rate_read(struct tb_switch *sw)
+{
+	int ret;
+	u32 val;
+
+	ret = tb_sw_read(sw, &val, TB_CFG_SWITCH,
+			 sw->tmu.cap + TMU_RTR_CS_3, 1);
+	if (ret)
+		return ret;
+
+	val >>= TMU_RTR_CS_3_TS_PACKET_INTERVAL_SHIFT;
+	return val;
+}
+
+static int tb_switch_tmu_rate_write(struct tb_switch *sw, int rate)
+{
+	int ret;
+	u32 val;
+
+	ret = tb_sw_read(sw, &val, TB_CFG_SWITCH,
+			 sw->tmu.cap + TMU_RTR_CS_3, 1);
+	if (ret)
+		return ret;
+
+	val &= ~TMU_RTR_CS_3_TS_PACKET_INTERVAL_MASK;
+	val |= rate << TMU_RTR_CS_3_TS_PACKET_INTERVAL_SHIFT;
+
+	return tb_sw_write(sw, &val, TB_CFG_SWITCH,
+			   sw->tmu.cap + TMU_RTR_CS_3, 1);
+}
+
+static int tb_port_tmu_write(struct tb_port *port, u8 offset, u32 mask,
+			     u32 value)
+{
+	u32 data;
+	int ret;
+
+	ret = tb_port_read(port, &data, TB_CFG_PORT, port->cap_tmu + offset, 1);
+	if (ret)
+		return ret;
+
+	data &= ~mask;
+	data |= value;
+
+	return tb_port_write(port, &data, TB_CFG_PORT,
+			     port->cap_tmu + offset, 1);
+}
+
+static int tb_port_tmu_set_unidirectional(struct tb_port *port,
+					  bool unidirectional)
+{
+	u32 val;
+
+	if (!port->sw->tmu.has_ucap)
+		return 0;
+
+	val = unidirectional ? TMU_ADP_CS_3_UDM : 0;
+	return tb_port_tmu_write(port, TMU_ADP_CS_3, TMU_ADP_CS_3_UDM, val);
+}
+
+static inline int tb_port_tmu_unidirectional_disable(struct tb_port *port)
+{
+	return tb_port_tmu_set_unidirectional(port, false);
+}
+
+static bool tb_port_tmu_is_unidirectional(struct tb_port *port)
+{
+	int ret;
+	u32 val;
+
+	ret = tb_port_read(port, &val, TB_CFG_PORT,
+			   port->cap_tmu + TMU_ADP_CS_3, 1);
+	if (ret)
+		return false;
+
+	return val & TMU_ADP_CS_3_UDM;
+}
+
+static int tb_switch_tmu_set_time_disruption(struct tb_switch *sw, bool set)
+{
+	int ret;
+	u32 val;
+
+	ret = tb_sw_read(sw, &val, TB_CFG_SWITCH,
+			 sw->tmu.cap + TMU_RTR_CS_0, 1);
+	if (ret)
+		return ret;
+
+	if (set)
+		val |= TMU_RTR_CS_0_TD;
+	else
+		val &= ~TMU_RTR_CS_0_TD;
+
+	return tb_sw_write(sw, &val, TB_CFG_SWITCH,
+			   sw->tmu.cap + TMU_RTR_CS_0, 1);
+}
+
+/**
+ * tb_switch_tmu_init() - Initialize switch TMU structures
+ * @sw: Switch to initialized
+ *
+ * This function must be called before other TMU related functions to
+ * makes the internal structures are filled in correctly. Does not
+ * change any hardware configuration.
+ */
+int tb_switch_tmu_init(struct tb_switch *sw)
+{
+	struct tb_port *port;
+	int ret;
+
+	if (tb_switch_is_icm(sw))
+		return 0;
+
+	ret = tb_switch_find_cap(sw, TB_SWITCH_CAP_TMU);
+	if (ret > 0)
+		sw->tmu.cap = ret;
+
+	tb_switch_for_each_port(sw, port) {
+		int cap;
+
+		cap = tb_port_find_cap(port, TB_PORT_CAP_TIME1);
+		if (cap > 0)
+			port->cap_tmu = cap;
+	}
+
+	ret = tb_switch_tmu_rate_read(sw);
+	if (ret < 0)
+		return ret;
+
+	sw->tmu.rate = ret;
+
+	sw->tmu.has_ucap = tb_switch_tmu_ucap_supported(sw);
+	if (sw->tmu.has_ucap) {
+		tb_sw_dbg(sw, "TMU: supports uni-directional mode\n");
+
+		if (tb_route(sw)) {
+			struct tb_port *up = tb_upstream_port(sw);
+
+			sw->tmu.unidirectional =
+				tb_port_tmu_is_unidirectional(up);
+		}
+	} else {
+		sw->tmu.unidirectional = false;
+	}
+
+	tb_sw_dbg(sw, "TMU: current mode: %s\n", tb_switch_tmu_mode_name(sw));
+	return 0;
+}
+
+/**
+ * tb_switch_tmu_post_time() - Update switch local time
+ * @sw: Switch whose time to update
+ *
+ * Updates switch local time using time posting procedure.
+ */
+int tb_switch_tmu_post_time(struct tb_switch *sw)
+{
+	unsigned int  post_local_time_offset, post_time_offset;
+	struct tb_switch *root_switch = sw->tb->root_switch;
+	u64 hi, mid, lo, local_time, post_time;
+	int i, ret, retries = 100;
+	u32 gm_local_time[3];
+
+	if (!tb_route(sw))
+		return 0;
+
+	if (!tb_switch_is_usb4(sw))
+		return 0;
+
+	/* Need to be able to read the grand master time */
+	if (!root_switch->tmu.cap)
+		return 0;
+
+	ret = tb_sw_read(root_switch, gm_local_time, TB_CFG_SWITCH,
+			 root_switch->tmu.cap + TMU_RTR_CS_1,
+			 ARRAY_SIZE(gm_local_time));
+	if (ret)
+		return ret;
+
+	for (i = 0; i < ARRAY_SIZE(gm_local_time); i++)
+		tb_sw_dbg(root_switch, "local_time[%d]=0x%08x\n", i,
+			  gm_local_time[i]);
+
+	/* Convert to nanoseconds (drop fractional part) */
+	hi = gm_local_time[2] & TMU_RTR_CS_3_LOCAL_TIME_NS_MASK;
+	mid = gm_local_time[1];
+	lo = (gm_local_time[0] & TMU_RTR_CS_1_LOCAL_TIME_NS_MASK) >>
+		TMU_RTR_CS_1_LOCAL_TIME_NS_SHIFT;
+	local_time = hi << 48 | mid << 16 | lo;
+
+	/* Tell the switch that time sync is disrupted for a while */
+	ret = tb_switch_tmu_set_time_disruption(sw, true);
+	if (ret)
+		return ret;
+
+	post_local_time_offset = sw->tmu.cap + TMU_RTR_CS_22;
+	post_time_offset = sw->tmu.cap + TMU_RTR_CS_24;
+
+	/*
+	 * Write the Grandmaster time to the Post Local Time registers
+	 * of the new switch.
+	 */
+	ret = tb_sw_write(sw, &local_time, TB_CFG_SWITCH,
+			  post_local_time_offset, 2);
+	if (ret)
+		goto out;
+
+	/*
+	 * Have the new switch update its local time (by writing 1 to
+	 * the post_time registers) and wait for the completion of the
+	 * same (post_time register becomes 0). This means the time has
+	 * been converged properly.
+	 */
+	post_time = 1;
+
+	ret = tb_sw_write(sw, &post_time, TB_CFG_SWITCH, post_time_offset, 2);
+	if (ret)
+		goto out;
+
+	do {
+		usleep_range(5, 10);
+		ret = tb_sw_read(sw, &post_time, TB_CFG_SWITCH,
+				 post_time_offset, 2);
+		if (ret)
+			goto out;
+	} while (--retries && post_time);
+
+	if (!retries) {
+		ret = -ETIMEDOUT;
+		goto out;
+	}
+
+	tb_sw_dbg(sw, "TMU: updated local time to %#llx\n", local_time);
+
+out:
+	tb_switch_tmu_set_time_disruption(sw, false);
+	return ret;
+}
+
+/**
+ * tb_switch_tmu_disable() - Disable TMU of a switch
+ * @sw: Switch whose TMU to disable
+ *
+ * Turns off TMU of @sw if it is enabled. If not enabled does nothing.
+ */
+int tb_switch_tmu_disable(struct tb_switch *sw)
+{
+	int ret;
+
+	if (!tb_switch_is_usb4(sw))
+		return 0;
+
+	/* Already disabled? */
+	if (sw->tmu.rate == TB_SWITCH_TMU_RATE_OFF)
+		return 0;
+
+	if (sw->tmu.unidirectional) {
+		struct tb_switch *parent = tb_switch_parent(sw);
+		struct tb_port *up, *down;
+
+		up = tb_upstream_port(sw);
+		down = tb_port_at(tb_route(sw), parent);
+
+		/* The switch may be unplugged so ignore any errors */
+		tb_port_tmu_unidirectional_disable(up);
+		ret = tb_port_tmu_unidirectional_disable(down);
+		if (ret)
+			return ret;
+	}
+
+	tb_switch_tmu_rate_write(sw, TB_SWITCH_TMU_RATE_OFF);
+
+	sw->tmu.unidirectional = false;
+	sw->tmu.rate = TB_SWITCH_TMU_RATE_OFF;
+
+	tb_sw_dbg(sw, "TMU: disabled\n");
+	return 0;
+}
+
+/**
+ * tb_switch_tmu_enable() - Enable TMU on a switch
+ * @sw: Switch whose TMU to enable
+ *
+ * Enables TMU of a switch to be in bi-directional, HiFi mode. In this mode
+ * all tunneling should work.
+ */
+int tb_switch_tmu_enable(struct tb_switch *sw)
+{
+	int ret;
+
+	if (!tb_switch_is_usb4(sw))
+		return 0;
+
+	if (tb_switch_tmu_is_enabled(sw))
+		return 0;
+
+	ret = tb_switch_tmu_set_time_disruption(sw, true);
+	if (ret)
+		return ret;
+
+	/* Change mode to bi-directional */
+	if (tb_route(sw) && sw->tmu.unidirectional) {
+		struct tb_switch *parent = tb_switch_parent(sw);
+		struct tb_port *up, *down;
+
+		up = tb_upstream_port(sw);
+		down = tb_port_at(tb_route(sw), parent);
+
+		ret = tb_port_tmu_unidirectional_disable(down);
+		if (ret)
+			return ret;
+
+		ret = tb_switch_tmu_rate_write(sw, TB_SWITCH_TMU_RATE_HIFI);
+		if (ret)
+			return ret;
+
+		ret = tb_port_tmu_unidirectional_disable(up);
+		if (ret)
+			return ret;
+	} else {
+		ret = tb_switch_tmu_rate_write(sw, TB_SWITCH_TMU_RATE_HIFI);
+		if (ret)
+			return ret;
+	}
+
+	sw->tmu.unidirectional = false;
+	sw->tmu.rate = TB_SWITCH_TMU_RATE_HIFI;
+	tb_sw_dbg(sw, "TMU: mode set to: %s\n", tb_switch_tmu_mode_name(sw));
+
+	return tb_switch_tmu_set_time_disruption(sw, false);
+}