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, 47 insertions, 0 deletions

diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
index 28dd0e0b1579..63ffb3cbdefe 100644
--- a/drivers/thunderbolt/tb.h
+++ b/drivers/thunderbolt/tb.h
@@ -47,6 +47,38 @@ struct tb_switch_nvm {
 #define USB4_SWITCH_MAX_DEPTH		5
 
 /**
+ * enum tb_switch_tmu_rate - TMU refresh rate
+ * @TB_SWITCH_TMU_RATE_OFF: %0 (Disable Time Sync handshake)
+ * @TB_SWITCH_TMU_RATE_HIFI: %16 us time interval between successive
+ *			     transmission of the Delay Request TSNOS
+ *			     (Time Sync Notification Ordered Set) on a Link
+ * @TB_SWITCH_TMU_RATE_NORMAL: %1 ms time interval between successive
+ *			       transmission of the Delay Request TSNOS on
+ *			       a Link
+ */
+enum tb_switch_tmu_rate {
+	TB_SWITCH_TMU_RATE_OFF = 0,
+	TB_SWITCH_TMU_RATE_HIFI = 16,
+	TB_SWITCH_TMU_RATE_NORMAL = 1000,
+};
+
+/**
+ * struct tb_switch_tmu - Structure holding switch TMU configuration
+ * @cap: Offset to the TMU capability (%0 if not found)
+ * @has_ucap: Does the switch support uni-directional mode
+ * @rate: TMU refresh rate related to upstream switch. In case of root
+ *	  switch this holds the domain rate.
+ * @unidirectional: Is the TMU in uni-directional or bi-directional mode
+ *		    related to upstream switch. Don't case for root switch.
+ */
+struct tb_switch_tmu {
+	int cap;
+	bool has_ucap;
+	enum tb_switch_tmu_rate rate;
+	bool unidirectional;
+};
+
+/**
  * struct tb_switch - a thunderbolt switch
  * @dev: Device for the switch
  * @config: Switch configuration
@@ -55,6 +87,7 @@ struct tb_switch_nvm {
  *	      mailbox this will hold the pointer to that (%NULL
  *	      otherwise). If set it also means the switch has
  *	      upgradeable NVM.
+ * @tmu: The switch TMU configuration
  * @tb: Pointer to the domain the switch belongs to
  * @uid: Unique ID of the switch
  * @uuid: UUID of the switch (or %NULL if not supported)
@@ -93,6 +126,7 @@ struct tb_switch {
 	struct tb_regs_switch_header config;
 	struct tb_port *ports;
 	struct tb_dma_port *dma_port;
+	struct tb_switch_tmu tmu;
 	struct tb *tb;
 	u64 uid;
 	uuid_t *uuid;
@@ -129,6 +163,7 @@ struct tb_switch {
  * @remote: Remote port (%NULL if not connected)
  * @xdomain: Remote host (%NULL if not connected)
  * @cap_phy: Offset, zero if not found
+ * @cap_tmu: Offset of the adapter specific TMU capability (%0 if not present)
  * @cap_adap: Offset of the adapter specific capability (%0 if not present)
  * @cap_usb4: Offset to the USB4 port capability (%0 if not present)
  * @port: Port number on switch
@@ -147,6 +182,7 @@ struct tb_port {
 	struct tb_port *remote;
 	struct tb_xdomain *xdomain;
 	int cap_phy;
+	int cap_tmu;
 	int cap_adap;
 	int cap_usb4;
 	u8 port;
@@ -672,6 +708,17 @@ bool tb_switch_query_dp_resource(struct tb_switch *sw, struct tb_port *in);
 int tb_switch_alloc_dp_resource(struct tb_switch *sw, struct tb_port *in);
 void tb_switch_dealloc_dp_resource(struct tb_switch *sw, struct tb_port *in);
 
+int tb_switch_tmu_init(struct tb_switch *sw);
+int tb_switch_tmu_post_time(struct tb_switch *sw);
+int tb_switch_tmu_disable(struct tb_switch *sw);
+int tb_switch_tmu_enable(struct tb_switch *sw);
+
+static inline bool tb_switch_tmu_is_enabled(const struct tb_switch *sw)
+{
+	return sw->tmu.rate == TB_SWITCH_TMU_RATE_HIFI &&
+	       !sw->tmu.unidirectional;
+}
+
 int tb_wait_for_port(struct tb_port *port, bool wait_if_unplugged);
 int tb_port_add_nfc_credits(struct tb_port *port, int credits);
 int tb_port_set_initial_credits(struct tb_port *port, u32 credits);