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usb: typec: tcpm: Implement enabling Auto Discharge disconnect support

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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: Badhri Jagan Sridharan <badhri@google.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20201029063138.1429760-8-badhri@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Badhri Jagan Sridharan 2020-10-28 23:31:35 -07:00 committed by Greg Kroah-Hartman
parent 2fc58b36e9
commit f321a02cae
2 changed files with 71 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

60
drivers/usb/typec/tcpm/tcpm.c
View File

@ -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);

15
include/linux/usb/tcpm.h
View File

@ -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;