pd: Add Try.SRC functionality to the pd_protocol state machine

	1. Added new config option CONFIG_USB_PD_TRY_SRC
	2. Added pd_try_source_enable global flag with console command
	3. Added bit to pd.flags to indicate Try.SRC states are active

BUG=chrome-os-partner:39724
TEST=Manual samus to samus with the Try.SRC enabled on both and just
     one samus. Tested Samus to Honeybuns and Samus to Zinger connections.
BRANCH=TOT

Change-Id: Ifa5d5d82e443f376e546aaf852ff24d92ef04d72
Signed-off-by: Scott Collyer <scollyer@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/282052
Reviewed-by: Alec Berg <alecaberg@chromium.org>
Tested-by: Alec Berg <alecaberg@chromium.org>

4 files changed, 122 insertions, 17 deletions

diff --git a/board/samus_pd/board.h b/board/samus_pd/board.h
index 1d54501e61..a2cba6d77c 100644
--- a/board/samus_pd/board.h
+++ b/board/samus_pd/board.h
@@ -52,6 +52,7 @@
 #define CONFIG_USB_PD_COMM_ENABLED 0
 #define CONFIG_USB_PD_CUSTOM_VDM
 #define CONFIG_USB_PD_DUAL_ROLE
+#define CONFIG_USB_PD_TRY_SRC
 #define CONFIG_USB_PD_FLASH_ERASE_CHECK
 #define CONFIG_USB_PD_INTERNAL_COMP
 #define CONFIG_USB_PD_LOGGING
diff --git a/common/usb_pd_protocol.c b/common/usb_pd_protocol.c
index 25774cd62e..3ca0ab2733 100644
--- a/common/usb_pd_protocol.c
+++ b/common/usb_pd_protocol.c
@@ -87,6 +87,9 @@ enum pd_dual_role_states drp_state = PD_DRP_TOGGLE_OFF;
 /* Last received source cap */
 static uint32_t pd_src_caps[CONFIG_USB_PD_PORT_COUNT][PDO_MAX_OBJECTS];
 static int pd_src_cap_cnt[CONFIG_USB_PD_PORT_COUNT];
+
+/* Enable varible for Try.SRC states */
+static uint8_t pd_try_src_enable;
 #endif
 
 static struct pd_protocol {
@@ -127,6 +130,8 @@ static struct pd_protocol {
 	int new_power_request;
 	/* Store previously requested voltage request */
 	int prev_request_mv;
+	/* Time for Try.SRC states */
+	uint64_t try_src_marker;
 #endif
 
 	/* PD state for Vendor Defined Messages */
@@ -260,6 +265,9 @@ static inline void set_state(int port, enum pd_states next_state)
 		typec_set_input_current_limit(port, 0, 0);
 		charge_manager_set_ceil(port, CHARGE_CEIL_NONE);
 #endif
+#ifdef CONFIG_USBC_VCONN
+		tcpm_set_vconn(port, 0);
+#endif
 #else /* CONFIG_USB_PD_DUAL_ROLE */
 	if (next_state == PD_STATE_SRC_DISCONNECTED) {
 #endif
@@ -275,9 +283,6 @@ static inline void set_state(int port, enum pd_states next_state)
 		usb_mux_set(port, TYPEC_MUX_NONE, USB_SWITCH_DISCONNECT,
 			    pd[port].polarity);
 #endif
-#ifdef CONFIG_USBC_VCONN
-		tcpm_set_vconn(port, 0);
-#endif
 		/* Disable TCPC RX */
 		tcpm_set_rx_enable(port, 0);
 	}
@@ -1166,6 +1171,18 @@ void pd_set_dual_role(enum pd_dual_role_states state)
 	int i;
 	drp_state = state;
 
+#ifdef CONFIG_USB_PD_TRY_SRC
+	pd_try_src_enable = (state == PD_DRP_TOGGLE_ON) ? 1 : 0;
+	for (i = 0; i < CONFIG_USB_PD_PORT_COUNT; i++) {
+		/*
+		 * Clear this flag to cover case where a TrySrc
+		 * mode went from enabled to disabled and trying_source
+		 * was active at that time.
+		 */
+		pd[i].flags &= ~PD_FLAGS_TRY_SRC;
+	}
+#endif
+
 	for (i = 0; i < CONFIG_USB_PD_PORT_COUNT; i++) {
 		/*
 		 * Change to sink if port is currently a source AND (new DRP
@@ -1416,13 +1433,25 @@ void pd_task(void)
 					PD_STATE_SRC_DISCONNECTED_DEBOUNCE);
 			}
 #ifdef CONFIG_USB_PD_DUAL_ROLE
-			/* Swap roles if time expired */
-			else if (drp_state != PD_DRP_FORCE_SOURCE &&
-				 get_time().val >= next_role_swap) {
+			/*
+			 * Try.SRC state is embedded here. Wait for SNK
+			 * detect, or if timer expires, transition to
+			 * SNK_DISCONNETED.
+			 *
+			 * If Try.SRC state is not active, then this block
+			 * handles the normal DRP toggle from SRC->SNK
+			 */
+			else if ((pd[port].flags & PD_FLAGS_TRY_SRC &&
+				 get_time().val >= pd[port].try_src_marker) ||
+				 (!(pd[port].flags & PD_FLAGS_TRY_SRC) &&
+				  drp_state != PD_DRP_FORCE_SOURCE &&
+				 get_time().val >= next_role_swap)) {
 				pd[port].power_role = PD_ROLE_SINK;
 				set_state(port, PD_STATE_SNK_DISCONNECTED);
 				tcpm_set_cc(port, TYPEC_CC_RD);
 				next_role_swap = get_time().val + PD_T_DRP_SNK;
+				pd[port].try_src_marker = get_time().val
+					+ PD_T_TRY_WAIT;
 
 				/* Swap states quickly */
 				timeout = 2*MSEC;
@@ -1455,15 +1484,18 @@ void pd_task(void)
 				timeout = 5*MSEC;
 				break;
 			}
-
-			/* Debounce the cc state */
-			if (new_cc_state != pd[port].cc_state) {
-				pd[port].cc_debounce = get_time().val +
-						       PD_T_CC_DEBOUNCE;
-				pd[port].cc_state = new_cc_state;
-				break;
-			} else if (get_time().val < pd[port].cc_debounce) {
-				break;
+			/* If in Try.SRC state, then don't need to debounce */
+			if (!(pd[port].flags & PD_FLAGS_TRY_SRC)) {
+				/* Debounce the cc state */
+				if (new_cc_state != pd[port].cc_state) {
+					pd[port].cc_debounce = get_time().val +
+						PD_T_CC_DEBOUNCE;
+					pd[port].cc_state = new_cc_state;
+					break;
+				} else if (get_time().val <
+					   pd[port].cc_debounce) {
+					break;
+				}
 			}
 
 			/* Debounce complete */
@@ -1858,6 +1890,18 @@ void pd_task(void)
 			}
 
 			/*
+			 * If Try.SRC is active and failed to detect a SNK,
+			 * then it transitions to TryWait.SNK. Need to prevent
+			 * normal dual role toggle until tDRPTryWait timer
+			 * expires.
+			 */
+			if (pd[port].flags & PD_FLAGS_TRY_SRC) {
+				if (get_time().val > pd[port].try_src_marker)
+					pd[port].flags &= ~PD_FLAGS_TRY_SRC;
+				break;
+			}
+
+			/*
 			 * If no source detected, check for role toggle.
 			 * If VBUS is detected, and we are in the debug
 			 * accessory toggle state, then allow toggling.
@@ -1892,6 +1936,24 @@ void pd_task(void)
 			    !pd_snk_is_vbus_provided(port))
 				break;
 
+			if (pd_try_src_enable &&
+			    !(pd[port].flags & PD_FLAGS_TRY_SRC)) {
+				/*
+				 * If TRY_SRC is enabled, but not active,
+				 * then force attempt to connect as source.
+				 */
+				pd[port].try_src_marker = get_time().val
+					+ PD_T_TRY_SRC;
+				/* Swap roles to source */
+				pd[port].power_role = PD_ROLE_SOURCE;
+				tcpm_set_cc(port, TYPEC_CC_RP);
+				timeout = 2*MSEC;
+				set_state(port, PD_STATE_SRC_DISCONNECTED);
+				/* Set flag after the state change */
+				pd[port].flags |= PD_FLAGS_TRY_SRC;
+				break;
+			}
+
 			/* We are attached */
 			pd[port].polarity = (cc2 != TYPEC_CC_VOLT_OPEN);
 			tcpm_set_polarity(port, pd[port].polarity);
@@ -2376,6 +2438,26 @@ void pd_task(void)
 				set_state(port, PD_STATE_SRC_DISCONNECTED);
 				/* Debouncing */
 				timeout = 10*MSEC;
+#ifdef CONFIG_USB_PD_DUAL_ROLE
+				/*
+				 * If Try.SRC is configured, then ATTACHED_SRC
+				 * needs to transition to TryWait.SNK. Change
+				 * power role to SNK and start state timer.
+				 */
+				if (pd_try_src_enable) {
+					/* Swap roles to sink */
+					pd[port].power_role = PD_ROLE_SINK;
+					tcpm_set_cc(port, TYPEC_CC_RD);
+					/* Set timer for TryWait.SNK state */
+					pd[port].try_src_marker = get_time().val
+						+ PD_T_TRY_WAIT;
+					/* Advance to TryWait.SNK state */
+					set_state(port,
+						  PD_STATE_SNK_DISCONNECTED);
+					/* Mark state as TryWait.SNK */
+					pd[port].flags |= PD_FLAGS_TRY_SRC;
+				}
+#endif
 			}
 		}
 #ifdef CONFIG_USB_PD_DUAL_ROLE
@@ -2678,7 +2760,21 @@ static int command_pd(int argc, char **argv)
 		return EC_SUCCESS;
 	}
 #endif /* CONFIG_CMD_PD_DEV_DUMP_INFO */
+#ifdef CONFIG_USB_PD_TRY_SRC
+	else if (!strncasecmp(argv[1], "trysrc", 6)) {
+		int enable;
+
+		if (argc < 3)
+			return EC_ERROR_PARAM_COUNT;
 
+		enable = strtoi(argv[2], &e, 10);
+		if (*e)
+			return EC_ERROR_PARAM3;
+		pd_try_src_enable = enable ? 1 : 0;
+		ccprintf("Try.SRC %s\n", enable ? "on" : "off");
+		return EC_SUCCESS;
+	}
+#endif
 #endif
 	/* command: pd <port> <subcmd> [args] */
 	port = strtoi(argv[1], &e, 10);
@@ -2800,7 +2896,8 @@ static int command_pd(int argc, char **argv)
 	return EC_SUCCESS;
 }
 DECLARE_CONSOLE_COMMAND(pd, command_pd,
-			"dualrole|dump|enable [0|1]|rwhashtable|\n\t<port> "
+			"dualrole|dump|enable [0|1]|rwhashtable"
+			"trysrc [0|1]\n\t<port> "
 			"[tx|bist_rx|bist_tx|charger|clock|dev"
 			"|soft|hash|hard|ping|state|swap [power|data]|"
 			"vdm [ping | curr | vers]]",
diff --git a/include/config.h b/include/config.h
index 3bff029e2f..b456a81f39 100644
--- a/include/config.h
+++ b/include/config.h
@@ -1535,6 +1535,9 @@
 /* Define the type-c port controller I2C base address. */
 #undef CONFIG_TCPC_I2C_BASE_ADDR
 
+/* Use this option to enable Try.SRC mode for Dual Role devices */
+#undef CONFIG_USB_PD_TRY_SRC
+
 /* Alternative configuration keeping only the TX part of PHY */
 #undef CONFIG_USB_PD_TX_PHY_ONLY
 
diff --git a/include/usb_pd.h b/include/usb_pd.h
index a5bfe7ab3b..6950e8065b 100644
--- a/include/usb_pd.h
+++ b/include/usb_pd.h
@@ -160,6 +160,8 @@ enum pd_rx_errors {
 #define PD_T_BIST_TRANSMIT     (50*MSEC) /* 50ms (used for task_wait arg) */
 #define PD_T_BIST_RECEIVE      (60*MSEC) /* 60ms (max time to process bist) */
 #define PD_T_VCONN_SOURCE_ON  (100*MSEC) /* 100ms */
+#define PD_T_TRY_SRC          (125*MSEC) /* Max time for Try.SRC state */
+#define PD_T_TRY_WAIT         (600*MSEC) /* Max time for TryWait.SNK state */
 
 /* number of edges and time window to detect CC line is not idle */
 #define PD_RX_TRANSITION_COUNT  3
@@ -699,6 +701,7 @@ enum pd_states {
 #define PD_FLAGS_CHECK_DR_ROLE     (1 << 10)/* check data role in READY */
 #define PD_FLAGS_PARTNER_EXTPOWER  (1 << 11)/* port partner has external pwr */
 #define PD_FLAGS_VCONN_ON          (1 << 12)/* vconn is being sourced */
+#define PD_FLAGS_TRY_SRC           (1 << 13)/* Try.SRC states are active */
 /* Flags to clear on a disconnect */
 #define PD_FLAGS_RESET_ON_DISCONNECT_MASK (PD_FLAGS_PARTNER_DR_POWER | \
 					   PD_FLAGS_PARTNER_DR_DATA | \
@@ -710,7 +713,8 @@ enum pd_states {
 					   PD_FLAGS_CHECK_PR_ROLE | \
 					   PD_FLAGS_CHECK_DR_ROLE | \
 					   PD_FLAGS_PARTNER_EXTPOWER | \
-					   PD_FLAGS_VCONN_ON)
+					   PD_FLAGS_VCONN_ON | \
+					   PD_FLAGS_TRY_SRC)
 
 
 enum pd_cc_states {