usb: typec: tcpm: Add support for Sink Fast Role SWAP(FRS)

PD 3.0 spec defines a new mechanism for power role swap called
Fast role swap. This change enables TCPM to support FRS when
acting as sink.

Once the explicit contract is negotiated, sink port is
expected to query the source port for sink caps to
determine whether the source is FRS capable.
Bits 23 & 24 of fixed pdo of the sink caps from the source, when
set, indicates the current needed by the source when fast role
swap is in progress(Implicit contract phasae). 0 indicates that
the source does not support Fast Role Swap.

Upon receiving the FRS signal from the source,
TCPC(TCPM_FRS_EVENT) informs TCPM to start the Fast role swap sequence.

1. TCPM sends FRS PD message: FR_SWAP_SEND
2. If response is not received within the expiry of
   SenderResponseTimer, Error recovery is triggered.:
   FR_SWAP_SEND_TIMEOUT
3. Upon receipt of the accept message, TCPM waits for
   PSSourceOffTimer for PS_READY message from the partner:
   FR_SWAP_SNK_SRC_NEW_SINK_READY.

TCPC is expected to autonomously turn on vbus once the FRS
signal is received and vbus voltage falls below vsafe5v within
tSrcFrSwap. This is different from traditional power role swap
where the vbus sourcing is turned on by TCPM.

4. By this time, TCPC most likely would have started to
   source vbus, TCPM waits for tSrcFrSwap to see  if the
   lower level TCPC driver signals TCPM_SOURCING_VBUS event:
   FR_SWAP_SNK_SRC_SOURCE_VBUS_APPLIED.
5. When TCPC signals sourcing vbus, TCPM sends PS_READY msg and
   changes the CC pin from Rd to Rp. This is the end of fast
   role swap sequence and TCPM initiates the sequnce to negotiate
   explicit contract by transitioning into SRC_STARTUP after
   SwapSrcStart.

The code is written based on the sequence described in "Figure 8-107:
Dual-role Port in Sink to Source Fast Role Swap State Diagram" of
USB Power Delivery Specification Revision 3.0, Version 1.2.

Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20201008061556.1402293-7-badhri@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 226 insertions, 3 deletions

diff --git a/drivers/usb/typec/tcpm/tcpm.c b/drivers/usb/typec/tcpm/tcpm.c
index 92806547f485..55535c4f66bf 100644
--- a/drivers/usb/typec/tcpm/tcpm.c
+++ b/drivers/usb/typec/tcpm/tcpm.c
@@ -106,6 +106,13 @@
 	S(VCONN_SWAP_TURN_ON_VCONN),		\
 	S(VCONN_SWAP_TURN_OFF_VCONN),		\
 						\
+	S(FR_SWAP_SEND),			\
+	S(FR_SWAP_SEND_TIMEOUT),		\
+	S(FR_SWAP_SNK_SRC_TRANSITION_TO_OFF),			\
+	S(FR_SWAP_SNK_SRC_NEW_SINK_READY),		\
+	S(FR_SWAP_SNK_SRC_SOURCE_VBUS_APPLIED),	\
+	S(FR_SWAP_CANCEL),			\
+						\
 	S(SNK_TRY),				\
 	S(SNK_TRY_WAIT),			\
 	S(SNK_TRY_WAIT_DEBOUNCE),               \
@@ -127,6 +134,9 @@
 	S(GET_PPS_STATUS_SEND),			\
 	S(GET_PPS_STATUS_SEND_TIMEOUT),		\
 						\
+	S(GET_SINK_CAP),			\
+	S(GET_SINK_CAP_TIMEOUT),		\
+						\
 	S(ERROR_RECOVERY),			\
 	S(PORT_RESET),				\
 	S(PORT_RESET_WAIT_OFF)
@@ -170,11 +180,25 @@ enum adev_actions {
 	ADEV_ATTENTION,
 };
 
+/*
+ * Initial current capability of the new source when vSafe5V is applied during PD3.0 Fast Role Swap.
+ * Based on "Table 6-14 Fixed Supply PDO - Sink" of "USB Power Delivery Specification Revision 3.0,
+ * Version 1.2"
+ */
+enum frs_typec_current {
+	FRS_NOT_SUPPORTED,
+	FRS_DEFAULT_POWER,
+	FRS_5V_1P5A,
+	FRS_5V_3A,
+};
+
 /* Events from low level driver */
 
 #define TCPM_CC_EVENT		BIT(0)
 #define TCPM_VBUS_EVENT		BIT(1)
 #define TCPM_RESET_EVENT	BIT(2)
+#define TCPM_FRS_EVENT		BIT(3)
+#define TCPM_SOURCING_VBUS	BIT(4)
 
 #define LOG_BUFFER_ENTRIES	1024
 #define LOG_BUFFER_ENTRY_SIZE	128
@@ -184,6 +208,8 @@ enum adev_actions {
 #define SVID_DISCOVERY_MAX	16
 #define ALTMODE_DISCOVERY_MAX	(SVID_DISCOVERY_MAX * MODE_DISCOVERY_MAX)
 
+#define GET_SINK_CAP_RETRY_MS	100
+
 struct pd_mode_data {
 	int svid_index;		/* current SVID index		*/
 	int nsvids;
@@ -261,6 +287,8 @@ struct tcpm_port {
 	struct kthread_work state_machine;
 	struct hrtimer vdm_state_machine_timer;
 	struct kthread_work vdm_state_machine;
+	struct hrtimer enable_frs_timer;
+	struct kthread_work enable_frs;
 	bool state_machine_running;
 
 	struct completion tx_complete;
@@ -335,6 +363,12 @@ struct tcpm_port {
 	/* port belongs to a self powered device */
 	bool self_powered;
 
+	/* FRS */
+	enum frs_typec_current frs_current;
+
+	/* Sink caps have been queried */
+	bool sink_cap_done;
+
 #ifdef CONFIG_DEBUG_FS
 	struct dentry *dentry;
 	struct mutex logbuffer_lock;	/* log buffer access lock */
@@ -940,6 +974,16 @@ static void mod_vdm_delayed_work(struct tcpm_port *port, unsigned int delay_ms)
 	}
 }
 
+static void mod_enable_frs_delayed_work(struct tcpm_port *port, unsigned int delay_ms)
+{
+	if (delay_ms) {
+		hrtimer_start(&port->enable_frs_timer, ms_to_ktime(delay_ms), HRTIMER_MODE_REL);
+	} else {
+		hrtimer_cancel(&port->enable_frs_timer);
+		kthread_queue_work(port->wq, &port->enable_frs);
+	}
+}
+
 static void tcpm_set_state(struct tcpm_port *port, enum tcpm_state state,
 			   unsigned int delay_ms)
 {
@@ -1669,6 +1713,9 @@ static void tcpm_pd_data_request(struct tcpm_port *port,
 	unsigned int cnt = pd_header_cnt_le(msg->header);
 	unsigned int rev = pd_header_rev_le(msg->header);
 	unsigned int i;
+	enum frs_typec_current frs_current;
+	bool frs_enable;
+	int ret;
 
 	switch (type) {
 	case PD_DATA_SOURCE_CAP:
@@ -1738,7 +1785,21 @@ static void tcpm_pd_data_request(struct tcpm_port *port,
 		/* We don't do anything with this at the moment... */
 		for (i = 0; i < cnt; i++)
 			port->sink_caps[i] = le32_to_cpu(msg->payload[i]);
+
+		frs_current = (port->sink_caps[0] & PDO_FIXED_FRS_CURR_MASK) >>
+			PDO_FIXED_FRS_CURR_SHIFT;
+		frs_enable = frs_current && (frs_current <= port->frs_current);
+		tcpm_log(port,
+			 "Port partner FRS capable partner_frs_current:%u port_frs_current:%u enable:%c",
+			 frs_current, port->frs_current, frs_enable ? 'y' : 'n');
+		if (frs_enable) {
+			ret  = port->tcpc->enable_frs(port->tcpc, true);
+			tcpm_log(port, "Enable FRS %s, ret:%d\n", ret ? "fail" : "success", ret);
+		}
+
 		port->nr_sink_caps = cnt;
+		port->sink_cap_done = true;
+		tcpm_set_state(port, SNK_READY, 0);
 		break;
 	case PD_DATA_VENDOR_DEF:
 		tcpm_handle_vdm_request(port, msg->payload, cnt);
@@ -1833,6 +1894,9 @@ static void tcpm_pd_ctrl_request(struct tcpm_port *port,
 		case VCONN_SWAP_WAIT_FOR_VCONN:
 			tcpm_set_state(port, VCONN_SWAP_TURN_OFF_VCONN, 0);
 			break;
+		case FR_SWAP_SNK_SRC_TRANSITION_TO_OFF:
+			tcpm_set_state(port, FR_SWAP_SNK_SRC_NEW_SINK_READY, 0);
+			break;
 		default:
 			break;
 		}
@@ -1872,6 +1936,13 @@ static void tcpm_pd_ctrl_request(struct tcpm_port *port,
 					     -EAGAIN : -EOPNOTSUPP);
 			tcpm_set_state(port, VCONN_SWAP_CANCEL, 0);
 			break;
+		case FR_SWAP_SEND:
+			tcpm_set_state(port, FR_SWAP_CANCEL, 0);
+			break;
+		case GET_SINK_CAP:
+			port->sink_cap_done = true;
+			tcpm_set_state(port, ready_state(port), 0);
+			break;
 		default:
 			break;
 		}
@@ -1906,6 +1977,9 @@ static void tcpm_pd_ctrl_request(struct tcpm_port *port,
 		case VCONN_SWAP_SEND:
 			tcpm_set_state(port, VCONN_SWAP_START, 0);
 			break;
+		case FR_SWAP_SEND:
+			tcpm_set_state(port, FR_SWAP_SNK_SRC_TRANSITION_TO_OFF, 0);
+			break;
 		default:
 			break;
 		}
@@ -2806,6 +2880,10 @@ static void tcpm_reset_port(struct tcpm_port *port)
 	port->try_src_count = 0;
 	port->try_snk_count = 0;
 	port->usb_type = POWER_SUPPLY_USB_TYPE_C;
+	port->nr_sink_caps = 0;
+	port->sink_cap_done = false;
+	if (port->tcpc->enable_frs)
+		port->tcpc->enable_frs(port->tcpc, false);
 
 	power_supply_changed(port->psy);
 }
@@ -3356,10 +3434,9 @@ static void run_state_machine(struct tcpm_port *port)
 		tcpm_swap_complete(port, 0);
 		tcpm_typec_connect(port);
 		tcpm_check_send_discover(port);
+		mod_enable_frs_delayed_work(port, 0);
 		tcpm_pps_complete(port, port->pps_status);
-
 		power_supply_changed(port->psy);
-
 		break;
 
 	/* Accessory states */
@@ -3383,9 +3460,13 @@ static void run_state_machine(struct tcpm_port *port)
 		tcpm_set_state(port, HARD_RESET_START, 0);
 		break;
 	case HARD_RESET_START:
+		port->sink_cap_done = false;
+		if (port->tcpc->enable_frs)
+			port->tcpc->enable_frs(port->tcpc, false);
 		port->hard_reset_count++;
 		port->tcpc->set_pd_rx(port->tcpc, false);
 		tcpm_unregister_altmodes(port);
+		port->nr_sink_caps = 0;
 		port->send_discover = true;
 		if (port->pwr_role == TYPEC_SOURCE)
 			tcpm_set_state(port, SRC_HARD_RESET_VBUS_OFF,
@@ -3517,6 +3598,35 @@ static void run_state_machine(struct tcpm_port *port)
 		tcpm_set_state(port, ready_state(port), 0);
 		break;
 
+	case FR_SWAP_SEND:
+		if (tcpm_pd_send_control(port, PD_CTRL_FR_SWAP)) {
+			tcpm_set_state(port, ERROR_RECOVERY, 0);
+			break;
+		}
+		tcpm_set_state_cond(port, FR_SWAP_SEND_TIMEOUT, PD_T_SENDER_RESPONSE);
+		break;
+	case FR_SWAP_SEND_TIMEOUT:
+		tcpm_set_state(port, ERROR_RECOVERY, 0);
+		break;
+	case FR_SWAP_SNK_SRC_TRANSITION_TO_OFF:
+		tcpm_set_state(port, ERROR_RECOVERY, PD_T_PS_SOURCE_OFF);
+		break;
+	case FR_SWAP_SNK_SRC_NEW_SINK_READY:
+		if (port->vbus_source)
+			tcpm_set_state(port, FR_SWAP_SNK_SRC_SOURCE_VBUS_APPLIED, 0);
+		else
+			tcpm_set_state(port, ERROR_RECOVERY, PD_T_RECEIVER_RESPONSE);
+		break;
+	case FR_SWAP_SNK_SRC_SOURCE_VBUS_APPLIED:
+		tcpm_set_pwr_role(port, TYPEC_SOURCE);
+		if (tcpm_pd_send_control(port, PD_CTRL_PS_RDY)) {
+			tcpm_set_state(port, ERROR_RECOVERY, 0);
+			break;
+		}
+		tcpm_set_cc(port, tcpm_rp_cc(port));
+		tcpm_set_state(port, SRC_STARTUP, PD_T_SWAP_SRC_START);
+		break;
+
 	/* PR_Swap states */
 	case PR_SWAP_ACCEPT:
 		tcpm_pd_send_control(port, PD_CTRL_ACCEPT);
@@ -3640,6 +3750,12 @@ static void run_state_machine(struct tcpm_port *port)
 		else
 			tcpm_set_state(port, SNK_READY, 0);
 		break;
+	case FR_SWAP_CANCEL:
+		if (port->pwr_role == TYPEC_SOURCE)
+			tcpm_set_state(port, SRC_READY, 0);
+		else
+			tcpm_set_state(port, SNK_READY, 0);
+		break;
 
 	case BIST_RX:
 		switch (BDO_MODE_MASK(port->bist_request)) {
@@ -3674,6 +3790,14 @@ static void run_state_machine(struct tcpm_port *port)
 	case GET_PPS_STATUS_SEND_TIMEOUT:
 		tcpm_set_state(port, ready_state(port), 0);
 		break;
+	case GET_SINK_CAP:
+		tcpm_pd_send_control(port, PD_CTRL_GET_SINK_CAP);
+		tcpm_set_state(port, GET_SINK_CAP_TIMEOUT, PD_T_SENDER_RESPONSE);
+		break;
+	case GET_SINK_CAP_TIMEOUT:
+		port->sink_cap_done = true;
+		tcpm_set_state(port, ready_state(port), 0);
+		break;
 	case ERROR_RECOVERY:
 		tcpm_swap_complete(port, -EPROTO);
 		tcpm_pps_complete(port, -EPROTO);
@@ -3889,6 +4013,13 @@ static void _tcpm_cc_change(struct tcpm_port *port, enum typec_cc_status cc1,
 		 * Ignore it.
 		 */
 		break;
+	case FR_SWAP_SEND:
+	case FR_SWAP_SEND_TIMEOUT:
+	case FR_SWAP_SNK_SRC_TRANSITION_TO_OFF:
+	case FR_SWAP_SNK_SRC_NEW_SINK_READY:
+	case FR_SWAP_SNK_SRC_SOURCE_VBUS_APPLIED:
+		/* Do nothing, CC change expected */
+		break;
 
 	case PORT_RESET:
 	case PORT_RESET_WAIT_OFF:
@@ -3959,6 +4090,9 @@ static void _tcpm_pd_vbus_on(struct tcpm_port *port)
 	case SRC_TRY_DEBOUNCE:
 		/* Do nothing, waiting for sink detection */
 		break;
+	case FR_SWAP_SNK_SRC_NEW_SINK_READY:
+		tcpm_set_state(port, FR_SWAP_SNK_SRC_SOURCE_VBUS_APPLIED, 0);
+		break;
 
 	case PORT_RESET:
 	case PORT_RESET_WAIT_OFF:
@@ -4038,6 +4172,14 @@ static void _tcpm_pd_vbus_off(struct tcpm_port *port)
 		 */
 		break;
 
+	case FR_SWAP_SEND:
+	case FR_SWAP_SEND_TIMEOUT:
+	case FR_SWAP_SNK_SRC_TRANSITION_TO_OFF:
+	case FR_SWAP_SNK_SRC_NEW_SINK_READY:
+	case FR_SWAP_SNK_SRC_SOURCE_VBUS_APPLIED:
+		/* Do nothing, vbus drop expected */
+		break;
+
 	default:
 		if (port->pwr_role == TYPEC_SINK &&
 		    port->attached)
@@ -4092,6 +4234,25 @@ static void tcpm_pd_event_handler(struct kthread_work *work)
 			if (port->tcpc->get_cc(port->tcpc, &cc1, &cc2) == 0)
 				_tcpm_cc_change(port, cc1, cc2);
 		}
+		if (events & TCPM_FRS_EVENT) {
+			if (port->state == SNK_READY)
+				tcpm_set_state(port, FR_SWAP_SEND, 0);
+			else
+				tcpm_log(port, "Discarding FRS_SIGNAL! Not in sink ready");
+		}
+		if (events & TCPM_SOURCING_VBUS) {
+			tcpm_log(port, "sourcing vbus");
+			/*
+			 * In fast role swap case TCPC autonomously sources vbus. Set vbus_source
+			 * true as TCPM wouldn't have called tcpm_set_vbus.
+			 *
+			 * When vbus is sourced on the command on TCPM i.e. TCPM called
+			 * tcpm_set_vbus to source vbus, vbus_source would already be true.
+			 */
+			port->vbus_source = true;
+			_tcpm_pd_vbus_on(port);
+		}
+
 		spin_lock(&port->pd_event_lock);
 	}
 	spin_unlock(&port->pd_event_lock);
@@ -4125,6 +4286,50 @@ void tcpm_pd_hard_reset(struct tcpm_port *port)
 }
 EXPORT_SYMBOL_GPL(tcpm_pd_hard_reset);
 
+void tcpm_sink_frs(struct tcpm_port *port)
+{
+	spin_lock(&port->pd_event_lock);
+	port->pd_events = TCPM_FRS_EVENT;
+	spin_unlock(&port->pd_event_lock);
+	kthread_queue_work(port->wq, &port->event_work);
+}
+EXPORT_SYMBOL_GPL(tcpm_sink_frs);
+
+void tcpm_sourcing_vbus(struct tcpm_port *port)
+{
+	spin_lock(&port->pd_event_lock);
+	port->pd_events = TCPM_SOURCING_VBUS;
+	spin_unlock(&port->pd_event_lock);
+	kthread_queue_work(port->wq, &port->event_work);
+}
+EXPORT_SYMBOL_GPL(tcpm_sourcing_vbus);
+
+static void tcpm_enable_frs_work(struct kthread_work *work)
+{
+	struct tcpm_port *port = container_of(work, struct tcpm_port, enable_frs);
+
+	mutex_lock(&port->lock);
+	/* Not FRS capable */
+	if (!port->connected || port->port_type != TYPEC_PORT_DRP ||
+	    port->pwr_opmode != TYPEC_PWR_MODE_PD ||
+	    !port->tcpc->enable_frs ||
+	    /* Sink caps queried */
+	    port->sink_cap_done || port->negotiated_rev < PD_REV30)
+		goto unlock;
+
+	/* Send when the state machine is idle */
+	if (port->state != SNK_READY || port->vdm_state != VDM_STATE_DONE || port->send_discover)
+		goto resched;
+
+	tcpm_set_state(port, GET_SINK_CAP, 0);
+	port->sink_cap_done = true;
+
+resched:
+	mod_enable_frs_delayed_work(port, GET_SINK_CAP_RETRY_MS);
+unlock:
+	mutex_unlock(&port->lock);
+}
+
 static int tcpm_dr_set(struct typec_port *p, enum typec_data_role data)
 {
 	struct tcpm_port *port = typec_get_drvdata(p);
@@ -4532,7 +4737,7 @@ static int tcpm_fw_get_caps(struct tcpm_port *port,
 {
 	const char *cap_str;
 	int ret;
-	u32 mw;
+	u32 mw, frs_current;
 
 	if (!fwnode)
 		return -EINVAL;
@@ -4601,6 +4806,13 @@ sink:
 
 	port->self_powered = fwnode_property_read_bool(fwnode, "self-powered");
 
+	/* FRS can only be supported byb DRP ports */
+	if (port->port_type == TYPEC_PORT_DRP) {
+		ret = fwnode_property_read_u32(fwnode, "frs-typec-current", &frs_current);
+		if (ret >= 0 && frs_current <= FRS_5V_3A)
+			port->frs_current = frs_current;
+	}
+
 	return 0;
 }
 
@@ -4845,6 +5057,14 @@ static enum hrtimer_restart vdm_state_machine_timer_handler(struct hrtimer *time
 	return HRTIMER_NORESTART;
 }
 
+static enum hrtimer_restart enable_frs_timer_handler(struct hrtimer *timer)
+{
+	struct tcpm_port *port = container_of(timer, struct tcpm_port, enable_frs_timer);
+
+	kthread_queue_work(port->wq, &port->enable_frs);
+	return HRTIMER_NORESTART;
+}
+
 struct tcpm_port *tcpm_register_port(struct device *dev, struct tcpc_dev *tcpc)
 {
 	struct tcpm_port *port;
@@ -4874,10 +5094,13 @@ struct tcpm_port *tcpm_register_port(struct device *dev, struct tcpc_dev *tcpc)
 	kthread_init_work(&port->state_machine, tcpm_state_machine_work);
 	kthread_init_work(&port->vdm_state_machine, vdm_state_machine_work);
 	kthread_init_work(&port->event_work, tcpm_pd_event_handler);
+	kthread_init_work(&port->enable_frs, tcpm_enable_frs_work);
 	hrtimer_init(&port->state_machine_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 	port->state_machine_timer.function = state_machine_timer_handler;
 	hrtimer_init(&port->vdm_state_machine_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 	port->vdm_state_machine_timer.function = vdm_state_machine_timer_handler;
+	hrtimer_init(&port->enable_frs_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	port->enable_frs_timer.function = enable_frs_timer_handler;
 
 	spin_lock_init(&port->pd_event_lock);