xref: /linux/drivers/thunderbolt/tmu.c (revision a28ec0e165ba2f90568828a2578aaa8540e13bc5)

// 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 inline int tb_port_tmu_unidirectional_enable(struct tb_port *port)
{
	return tb_port_tmu_set_unidirectional(port, true);
}

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_port_tmu_time_sync(struct tb_port *port, bool time_sync)
{
	u32 val = time_sync ? TMU_ADP_CS_6_DTS : 0;

	return tb_port_tmu_write(port, TMU_ADP_CS_6, TMU_ADP_CS_6_DTS, val);
}

static int tb_port_tmu_time_sync_disable(struct tb_port *port)
{
	return tb_port_tmu_time_sync(port, true);
}

static int tb_port_tmu_time_sync_enable(struct tb_port *port)
{
	return tb_port_tmu_time_sync(port, false);
}

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_time_high_offset, post_time_high = 0;
	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;
	post_time_high_offset = sw->tmu.cap + TMU_RTR_CS_25;

	/*
	 * 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:
	 * 1) writing 0x1 to the Post Time Low register and 0xffffffff to
	 * Post Time High register.
	 * 2) write 0 to Post Time High register and then wait for
	 * the completion of the post_time register becomes 0.
	 * This means the time has been converged properly.
	 */
	post_time = 0xffffffff00000001ULL;

	ret = tb_sw_write(sw, &post_time, TB_CFG_SWITCH, post_time_offset, 2);
	if (ret)
		goto out;

	ret = tb_sw_write(sw, &post_time_high, TB_CFG_SWITCH,
			  post_time_high_offset, 1);
	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)
{
	if (!tb_switch_is_usb4(sw))
		return 0;

	/* Already disabled? */
	if (sw->tmu.rate == TB_SWITCH_TMU_RATE_OFF)
		return 0;


	if (tb_route(sw)) {
		bool unidirectional = tb_switch_tmu_hifi_is_enabled(sw, true);
		struct tb_switch *parent = tb_switch_parent(sw);
		struct tb_port *down, *up;
		int ret;

		down = tb_port_at(tb_route(sw), parent);
		up = tb_upstream_port(sw);
		/*
		 * In case of uni-directional time sync, TMU handshake is
		 * initiated by upstream router. In case of bi-directional
		 * time sync, TMU handshake is initiated by downstream router.
		 * Therefore, we change the rate to off in the respective
		 * router.
		 */
		if (unidirectional)
			tb_switch_tmu_rate_write(parent, TB_SWITCH_TMU_RATE_OFF);
		else
			tb_switch_tmu_rate_write(sw, TB_SWITCH_TMU_RATE_OFF);

		tb_port_tmu_time_sync_disable(up);
		ret = tb_port_tmu_time_sync_disable(down);
		if (ret)
			return ret;

		if (unidirectional) {
			/* 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;
		}
	} else {
		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;
}

static void __tb_switch_tmu_off(struct tb_switch *sw, bool unidirectional)
{
	struct tb_switch *parent = tb_switch_parent(sw);
	struct tb_port *down, *up;

	down = tb_port_at(tb_route(sw), parent);
	up = tb_upstream_port(sw);
	/*
	 * In case of any failure in one of the steps when setting
	 * bi-directional or uni-directional TMU mode, get back to the TMU
	 * configurations in off mode. In case of additional failures in
	 * the functions below, ignore them since the caller shall already
	 * report a failure.
	 */
	tb_port_tmu_time_sync_disable(down);
	tb_port_tmu_time_sync_disable(up);
	if (unidirectional)
		tb_switch_tmu_rate_write(parent, TB_SWITCH_TMU_RATE_OFF);
	else
		tb_switch_tmu_rate_write(sw, TB_SWITCH_TMU_RATE_OFF);

	tb_port_tmu_unidirectional_disable(down);
	tb_port_tmu_unidirectional_disable(up);
}

/*
 * This function is called when the previous TMU mode was
 * TB_SWITCH_TMU_RATE_OFF.
 */
static int __tb_switch_tmu_enable_bidirectional(struct tb_switch *sw)
{
	struct tb_switch *parent = tb_switch_parent(sw);
	struct tb_port *up, *down;
	int ret;

	up = tb_upstream_port(sw);
	down = tb_port_at(tb_route(sw), parent);

	ret = tb_port_tmu_unidirectional_disable(up);
	if (ret)
		return ret;

	ret = tb_port_tmu_unidirectional_disable(down);
	if (ret)
		goto out;

	ret = tb_switch_tmu_rate_write(sw, TB_SWITCH_TMU_RATE_HIFI);
	if (ret)
		goto out;

	ret = tb_port_tmu_time_sync_enable(up);
	if (ret)
		goto out;

	ret = tb_port_tmu_time_sync_enable(down);
	if (ret)
		goto out;

	return 0;

out:
	__tb_switch_tmu_off(sw, false);
	return ret;
}

/*
 * This function is called when the previous TMU mode was
 * TB_SWITCH_TMU_RATE_OFF.
 */
static int __tb_switch_tmu_enable_unidirectional(struct tb_switch *sw)
{
	struct tb_switch *parent = tb_switch_parent(sw);
	struct tb_port *up, *down;
	int ret;

	up = tb_upstream_port(sw);
	down = tb_port_at(tb_route(sw), parent);
	ret = tb_switch_tmu_rate_write(parent, TB_SWITCH_TMU_RATE_HIFI);
	if (ret)
		return ret;

	ret = tb_port_tmu_unidirectional_enable(up);
	if (ret)
		goto out;

	ret = tb_port_tmu_time_sync_enable(up);
	if (ret)
		goto out;

	ret = tb_port_tmu_unidirectional_enable(down);
	if (ret)
		goto out;

	ret = tb_port_tmu_time_sync_enable(down);
	if (ret)
		goto out;

	return 0;

out:
	__tb_switch_tmu_off(sw, true);
	return ret;
}

static int tb_switch_tmu_hifi_enable(struct tb_switch *sw)
{
	bool unidirectional = sw->tmu.unidirectional_request;
	int ret;

	if (unidirectional && !sw->tmu.has_ucap)
		return -EOPNOTSUPP;

	if (!tb_switch_is_usb4(sw))
		return 0;

	if (tb_switch_tmu_hifi_is_enabled(sw, sw->tmu.unidirectional_request))
		return 0;

	ret = tb_switch_tmu_set_time_disruption(sw, true);
	if (ret)
		return ret;

	if (tb_route(sw)) {
		/* The used mode changes are from OFF to HiFi-Uni/HiFi-BiDir */
		if (sw->tmu.rate == TB_SWITCH_TMU_RATE_OFF) {
			if (unidirectional)
				ret = __tb_switch_tmu_enable_unidirectional(sw);
			else
				ret = __tb_switch_tmu_enable_bidirectional(sw);
			if (ret)
				return ret;
		}
		sw->tmu.unidirectional = unidirectional;
	} else {
		/*
		 * Host router port configurations are written as
		 * part of configurations for downstream port of the parent
		 * of the child node - see above.
		 * Here only the host router' rate configuration is written.
		 */
		ret = tb_switch_tmu_rate_write(sw, TB_SWITCH_TMU_RATE_HIFI);
		if (ret)
			return ret;
	}

	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);
}

/**
 * tb_switch_tmu_enable() - Enable TMU on a router
 * @sw: Router whose TMU to enable
 *
 * Enables TMU of a router to be in uni-directional or bi-directional HiFi mode.
 * Calling tb_switch_tmu_configure() is required before calling this function,
 * to select the mode HiFi and directionality (uni-directional/bi-directional).
 * In both modes all tunneling should work. Uni-directional mode is required for
 * CLx (Link Low-Power) to work.
 */
int tb_switch_tmu_enable(struct tb_switch *sw)
{
	if (sw->tmu.rate_request == TB_SWITCH_TMU_RATE_NORMAL)
		return -EOPNOTSUPP;

	return tb_switch_tmu_hifi_enable(sw);
}

/**
 * tb_switch_tmu_configure() - Configure the TMU rate and directionality
 * @sw: Router whose mode to change
 * @rate: Rate to configure Off/LowRes/HiFi
 * @unidirectional: If uni-directional (bi-directional otherwise)
 *
 * Selects the rate of the TMU and directionality (uni-directional or
 * bi-directional). Must be called before tb_switch_tmu_enable().
 */
void tb_switch_tmu_configure(struct tb_switch *sw,
			     enum tb_switch_tmu_rate rate, bool unidirectional)
{
	sw->tmu.unidirectional_request = unidirectional;
	sw->tmu.rate_request = rate;
}