Commit f321a02c authored by Badhri Jagan Sridharan's avatar Badhri Jagan Sridharan Committed by Greg Kroah-Hartman
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usb: typec: tcpm: Implement enabling Auto Discharge disconnect support 



TCPCI spec allows TCPC hardware to autonomously discharge the vbus
capacitance upon disconnect. The expectation is that the TCPM enables
AutoDischargeDisconnect while entering SNK/SRC_ATTACHED states. Hardware
then automously discharges vbus when the vbus falls below a certain
threshold i.e. VBUS_SINK_DISCONNECT_THRESHOLD.

Apart from enabling the vbus discharge circuit, AutoDischargeDisconnect
is also used a flag to move TCPCI based TCPC implementations into
Attached.Snk/Attached.Src state as mentioned in
Figure 4-15. TCPC State Diagram before a Connection of the
USB Type-C Port Controller Interface Specification.
In such TCPC implementations, setting AutoDischargeDisconnect would
prevent TCPC into entering "Connection_Invalid" state as well.

Signed-off-by: default avatarBadhri Jagan Sridharan <badhri@google.com>
Reviewed-by: default avatarHeikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20201029063138.1429760-8-badhri@google.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 2fc58b36

drivers/usb/typec/tcpm/tcpm.c

+56 −4
Original line number Diff line number Diff line
@@ -1706,6 +1706,24 @@ static void tcpm_handle_alert(struct tcpm_port *port, const __le32 *payload, 
	}

}



static int tcpm_set_auto_vbus_discharge_threshold(struct tcpm_port *port,

						  enum typec_pwr_opmode mode, bool pps_active,

						  u32 requested_vbus_voltage)

{

	int ret;



	if (!port->tcpc->set_auto_vbus_discharge_threshold)

		return 0;



	ret = port->tcpc->set_auto_vbus_discharge_threshold(port->tcpc, mode, pps_active,

							    requested_vbus_voltage);

	tcpm_log_force(port,

		       "set_auto_vbus_discharge_threshold mode:%d pps_active:%c vbus:%u ret:%d",

		       mode, pps_active ? 'y' : 'n', requested_vbus_voltage, ret);



	return ret;

}



static void tcpm_pd_data_request(struct tcpm_port *port,

				 const struct pd_message *msg)

{
@@ -1876,6 +1894,10 @@ static void tcpm_pd_ctrl_request(struct tcpm_port *port, 
						       port->current_limit,

						       port->supply_voltage);

				port->explicit_contract = true;

				tcpm_set_auto_vbus_discharge_threshold(port,

								       TYPEC_PWR_MODE_PD,

								       port->pps_data.active,

								       port->supply_voltage);

				tcpm_set_state(port, SNK_READY, 0);

			} else {

				/*
@@ -2790,8 +2812,12 @@ static int tcpm_src_attach(struct tcpm_port *port) 
	if (ret < 0)

		return ret;



	ret = tcpm_set_roles(port, true, TYPEC_SOURCE,

			     tcpm_data_role_for_source(port));

	if (port->tcpc->enable_auto_vbus_discharge) {

		ret = port->tcpc->enable_auto_vbus_discharge(port->tcpc, true);

		tcpm_log_force(port, "enable vbus discharge ret:%d", ret);

	}



	ret = tcpm_set_roles(port, true, TYPEC_SOURCE, tcpm_data_role_for_source(port));

	if (ret < 0)

		return ret;
@@ -2858,6 +2884,12 @@ static void tcpm_unregister_altmodes(struct tcpm_port *port) 


static void tcpm_reset_port(struct tcpm_port *port)

{

	int ret;



	if (port->tcpc->enable_auto_vbus_discharge) {

		ret = port->tcpc->enable_auto_vbus_discharge(port->tcpc, false);

		tcpm_log_force(port, "Disable vbus discharge ret:%d", ret);

	}

	tcpm_unregister_altmodes(port);

	tcpm_typec_disconnect(port);

	port->attached = false;
@@ -2922,8 +2954,13 @@ static int tcpm_snk_attach(struct tcpm_port *port) 
	if (ret < 0)

		return ret;



	ret = tcpm_set_roles(port, true, TYPEC_SINK,

			     tcpm_data_role_for_sink(port));

	if (port->tcpc->enable_auto_vbus_discharge) {

		tcpm_set_auto_vbus_discharge_threshold(port, TYPEC_PWR_MODE_USB, false, VSAFE5V);

		ret = port->tcpc->enable_auto_vbus_discharge(port->tcpc, true);

		tcpm_log_force(port, "enable vbus discharge ret:%d", ret);

	}



	ret = tcpm_set_roles(port, true, TYPEC_SINK, tcpm_data_role_for_sink(port));

	if (ret < 0)

		return ret;
@@ -3507,6 +3544,8 @@ static void run_state_machine(struct tcpm_port *port) 
		tcpm_set_state(port, SRC_UNATTACHED, PD_T_PS_SOURCE_ON);

		break;

	case SNK_HARD_RESET_SINK_OFF:

		/* Do not discharge/disconnect during hard reseet */

		tcpm_set_auto_vbus_discharge_threshold(port, TYPEC_PWR_MODE_USB, false, 0);

		memset(&port->pps_data, 0, sizeof(port->pps_data));

		tcpm_set_vconn(port, false);

		if (port->pd_capable)
@@ -3549,6 +3588,7 @@ static void run_state_machine(struct tcpm_port *port) 
			tcpm_set_charge(port, true);

		}

		tcpm_set_attached_state(port, true);

		tcpm_set_auto_vbus_discharge_threshold(port, TYPEC_PWR_MODE_USB, false, VSAFE5V);

		tcpm_set_state(port, SNK_STARTUP, 0);

		break;
@@ -3650,6 +3690,10 @@ static void run_state_machine(struct tcpm_port *port) 
			tcpm_set_state(port, PR_SWAP_SNK_SRC_SINK_OFF, 0);

		break;

	case PR_SWAP_SRC_SNK_TRANSITION_OFF:

		/*

		 * Prevent vbus discharge circuit from turning on during PR_SWAP

		 * as this is not a disconnect.

		 */

		tcpm_set_vbus(port, false);

		port->explicit_contract = false;

		/* allow time for Vbus discharge, must be < tSrcSwapStdby */
@@ -3678,9 +3722,17 @@ static void run_state_machine(struct tcpm_port *port) 
		tcpm_set_state_cond(port, SNK_UNATTACHED, PD_T_PS_SOURCE_ON);

		break;

	case PR_SWAP_SRC_SNK_SINK_ON:

		/* Set the vbus disconnect threshold for implicit contract */

		tcpm_set_auto_vbus_discharge_threshold(port, TYPEC_PWR_MODE_USB, false, VSAFE5V);

		tcpm_set_state(port, SNK_STARTUP, 0);

		break;

	case PR_SWAP_SNK_SRC_SINK_OFF:

		/*

		 * Prevent vbus discharge circuit from turning on during PR_SWAP

		 * as this is not a disconnect.

		 */

		tcpm_set_auto_vbus_discharge_threshold(port, TYPEC_PWR_MODE_USB,

						       port->pps_data.active, 0);

		tcpm_set_charge(port, false);

		tcpm_set_state(port, hard_reset_state(port),

			       PD_T_PS_SOURCE_OFF);

include/linux/usb/tcpm.h

+15 −0
Original line number Diff line number Diff line
@@ -86,6 +86,18 @@ enum tcpm_transmit_type { 
 * @frs_sourcing_vbus:

 *		Optional; Called to notify that vbus is now being sourced.

 *		Low level drivers can perform chip specific operations, if any.

 * @enable_auto_vbus_discharge:

 *		Optional; TCPCI spec based TCPC implementations can optionally

 *		support hardware to autonomously dischrge vbus upon disconnecting

 *		as sink or source. TCPM signals TCPC to enable the mechanism upon

 *		entering connected state and signals disabling upon disconnect.

 * @set_auto_vbus_discharge_threshold:

 *		Mandatory when enable_auto_vbus_discharge is implemented. TCPM

 *		calls this function to allow lower levels drivers to program the

 *		vbus threshold voltage below which the vbus discharge circuit

 *		will be turned on. requested_vbus_voltage is set to 0 when vbus

 *		is going to disappear knowingly i.e. during PR_SWAP and

 *		HARD_RESET etc.

 */

struct tcpc_dev {

	struct fwnode_handle *fwnode;
@@ -113,6 +125,9 @@ struct tcpc_dev { 
	int (*set_bist_data)(struct tcpc_dev *dev, bool on);

	int (*enable_frs)(struct tcpc_dev *dev, bool enable);

	void (*frs_sourcing_vbus)(struct tcpc_dev *dev);

	int (*enable_auto_vbus_discharge)(struct tcpc_dev *dev, bool enable);

	int (*set_auto_vbus_discharge_threshold)(struct tcpc_dev *dev, enum typec_pwr_opmode mode,

						 bool pps_active, u32 requested_vbus_voltage);

};



struct tcpm_port;