usb: differentiate DTS polarity and normal device polarity

When we have SNK_DTS polarity, we still want to drive both CC
lines with the appropriate pull.  SRC_DTS should not show as
having a polarity.  Non-DTS should show the correct polarity.
We were only handling the last sentence of that.

BUG=b:147754772
BRANCH=none
TEST=verify SuzyQ works on zork

Change-Id: I013f9d881427d6d97b655f88cfb3a94e3ed10c61
Signed-off-by: Denis Brockus <dbrockus@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2022914
Tested-by: David Schneider <dnschneid@chromium.org>
Reviewed-by: Jett Rink <jettrink@chromium.org>

6 files changed, 67 insertions, 14 deletions

diff --git a/common/usb_common.c b/common/usb_common.c
index fb3ebe84e0..9ac17802d2 100644
--- a/common/usb_common.c
+++ b/common/usb_common.c
@@ -69,8 +69,11 @@ typec_current_t usb_get_typec_current_limit(enum tcpc_cc_polarity polarity,
 	enum tcpc_cc_voltage_status cc1, enum tcpc_cc_voltage_status cc2)
 {
 	typec_current_t charge = 0;
-	enum tcpc_cc_voltage_status cc = polarity ? cc2 : cc1;
-	enum tcpc_cc_voltage_status cc_alt = polarity ? cc1 : cc2;
+	enum tcpc_cc_voltage_status cc;
+	enum tcpc_cc_voltage_status cc_alt;
+
+	cc = polarity_rm_dts(polarity) ? cc2 : cc1;
+	cc_alt = polarity_rm_dts(polarity) ? cc1 : cc2;
 
 	switch (cc) {
 	case TYPEC_CC_VOLT_RP_3_0:
@@ -110,16 +113,20 @@ enum tcpc_cc_polarity get_snk_polarity(enum tcpc_cc_voltage_status cc1,
 	 * TYPEC_CC_VOLT_RP_1_5 > TYPEC_CC_VOLT_RP_DEF
 	 * TYPEC_CC_VOLT_RP_DEF > TYPEC_CC_VOLT_OPEN
 	 */
-	return cc2 > cc1;
+	if (cc_is_src_dbg_acc(cc1, cc2))
+		return (cc1 > cc2) ? POLARITY_CC1_DTS : POLARITY_CC2_DTS;
+
+	return (cc1 > cc2) ? POLARITY_CC1 : POLARITY_CC2;
 }
 
 enum tcpc_cc_polarity get_src_polarity(enum tcpc_cc_voltage_status cc1,
 	enum tcpc_cc_voltage_status cc2)
 {
-	if (cc_is_open(cc1, cc2))
+	if (cc_is_open(cc1, cc2) ||
+	    cc_is_snk_dbg_acc(cc1, cc2))
 		return POLARITY_NONE;
 
-	return cc1 != TYPEC_CC_VOLT_RD;
+	return (cc1 == TYPEC_CC_VOLT_RD) ? POLARITY_CC1 : POLARITY_CC2;
 }
 
 enum pd_cc_states pd_get_cc_state(
diff --git a/driver/tcpm/anx7447.c b/driver/tcpm/anx7447.c
index a765af5c2e..ed4e601f6c 100644
--- a/driver/tcpm/anx7447.c
+++ b/driver/tcpm/anx7447.c
@@ -655,7 +655,8 @@ static int anx7447_set_polarity(int port, enum tcpc_cc_polarity polarity)
 	return tcpc_update8(port,
 			    TCPC_REG_TCPC_CTRL,
 			    TCPC_REG_TCPC_CTRL_SET(1),
-			    (polarity) ? MASK_SET : MASK_CLR);
+			    polarity_rm_dts(polarity)
+					? MASK_SET : MASK_CLR);
 }
 
 /*
diff --git a/driver/tcpm/anx74xx.c b/driver/tcpm/anx74xx.c
index c91c39bc58..7cdde05410 100644
--- a/driver/tcpm/anx74xx.c
+++ b/driver/tcpm/anx74xx.c
@@ -776,7 +776,7 @@ static int anx74xx_tcpm_set_polarity(int port, enum tcpc_cc_polarity polarity)
 		return EC_SUCCESS;
 
 	rv |= tcpc_read(port, ANX74XX_REG_CC_SOFTWARE_CTRL, &reg);
-	if (polarity) /* Inform ANX to use CC2 */
+	if (polarity_rm_dts(polarity)) /* Inform ANX to use CC2 */
 		reg &= ~ANX74XX_REG_SELECT_CC1;
 	else /* Inform ANX to use CC1 */
 		reg |= ANX74XX_REG_SELECT_CC1;
@@ -787,7 +787,7 @@ static int anx74xx_tcpm_set_polarity(int port, enum tcpc_cc_polarity polarity)
 	/* Update mux polarity */
 #ifdef CONFIG_USB_PD_TCPM_MUX
 	mux_state = anx[port].mux_state & ~USB_PD_MUX_POLARITY_INVERTED;
-	if (polarity)
+	if (polarity_rm_dts(polarity))
 		mux_state |= USB_PD_MUX_POLARITY_INVERTED;
 	anx74xx_tcpm_mux_set(port, mux_state);
 #endif
diff --git a/driver/tcpm/fusb302.c b/driver/tcpm/fusb302.c
index dc31228506..691e876435 100644
--- a/driver/tcpm/fusb302.c
+++ b/driver/tcpm/fusb302.c
@@ -586,7 +586,7 @@ static int fusb302_tcpm_set_polarity(int port, enum tcpc_cc_polarity polarity)
 
 	if (state[port].vconn_enabled) {
 		/* set VCONN switch to be non-CC line */
-		if (polarity)
+		if (polarity_rm_dts(polarity))
 			reg |= TCPC_REG_SWITCHES0_VCONN_CC1;
 		else
 			reg |= TCPC_REG_SWITCHES0_VCONN_CC2;
@@ -597,7 +597,7 @@ static int fusb302_tcpm_set_polarity(int port, enum tcpc_cc_polarity polarity)
 	reg &= ~TCPC_REG_SWITCHES0_MEAS_CC2;
 
 	/* set rx polarity */
-	if (polarity)
+	if (polarity_rm_dts(polarity))
 		reg |= TCPC_REG_SWITCHES0_MEAS_CC2;
 	else
 		reg |= TCPC_REG_SWITCHES0_MEAS_CC1;
@@ -611,7 +611,7 @@ static int fusb302_tcpm_set_polarity(int port, enum tcpc_cc_polarity polarity)
 	reg &= ~TCPC_REG_SWITCHES1_TXCC2_EN;
 
 	/* set tx polarity */
-	if (polarity)
+	if (polarity_rm_dts(polarity))
 		reg |= TCPC_REG_SWITCHES1_TXCC2_EN;
 	else
 		reg |= TCPC_REG_SWITCHES1_TXCC1_EN;
diff --git a/driver/tcpm/tcpci.c b/driver/tcpm/tcpci.c
index c369d0c48b..f97644a169 100644
--- a/driver/tcpm/tcpci.c
+++ b/driver/tcpm/tcpci.c
@@ -418,8 +418,8 @@ int tcpci_tcpm_set_polarity(int port, enum tcpc_cc_polarity polarity)
 
 	/*
 	 * TCPCI sets the CC lines based on polarity.  If it is set to
-	 * no connection then both CC lines are driven, otherwise only
-	 * one is driven.
+	 * no connection or SRC Debug Accessory then both CC lines are
+	 * driven, otherwise only one is driven.
 	 */
 	rv = tcpm_set_cc(port, tcpci_get_cached_pull(port));
 	if (rv)
@@ -431,7 +431,8 @@ int tcpci_tcpm_set_polarity(int port, enum tcpc_cc_polarity polarity)
 	return tcpc_update8(port,
 			    TCPC_REG_TCPC_CTRL,
 			    TCPC_REG_TCPC_CTRL_SET(1),
-			    (polarity) ? MASK_SET : MASK_CLR);
+			    polarity_rm_dts(polarity)
+					? MASK_SET : MASK_CLR);
 }
 
 #ifdef CONFIG_USBC_PPC
diff --git a/include/usb_pd_tcpm.h b/include/usb_pd_tcpm.h
index 9a4140afb4..97b0ec0864 100644
--- a/include/usb_pd_tcpm.h
+++ b/include/usb_pd_tcpm.h
@@ -50,11 +50,46 @@ enum tcpc_rp_value {
 };
 
 enum tcpc_cc_polarity {
+	/*
+	 * _NONE: either disconnected or connected to a SNK Debug
+	 * Accessory
+	 */
 	POLARITY_NONE = -1,
+
+	/*
+	 * _CCx: is used to indicate the polarity while not connected to
+	 * a Debug Accessory.  Only one CC line will assert a resistor and
+	 * the other will be open.
+	 */
 	POLARITY_CC1 = 0,
 	POLARITY_CC2 = 1,
+
+	/*
+	 * CCx_DTS is used to indicate the polarity while connected to a
+	 * SRC Debug Accessory.  Assert resistors on both lines.
+	 */
+	POLARITY_CC1_DTS = 2,
+	POLARITY_CC2_DTS = 3,
+
+	/*
+	 * The current TCPC code relies on these specific POLARITY values.
+	 * Adding in a check to verify if the list grows for any reason
+	 * that this will give a hint that other places need to be
+	 * adjusted.
+	 */
+	POLARITY_COUNT
 };
 
+/**
+ * Returns whether the polarity without the DTS extension
+ */
+static inline enum tcpc_cc_polarity polarity_rm_dts(
+	enum tcpc_cc_polarity polarity)
+{
+	BUILD_ASSERT(POLARITY_COUNT == 4);
+	return (polarity == POLARITY_NONE) ? polarity : polarity & BIT(0);
+}
+
 enum tcpm_transmit_type {
 	TCPC_TX_SOP = 0,
 	TCPC_TX_SOP_PRIME = 1,
@@ -104,6 +139,15 @@ static inline int cc_is_snk_dbg_acc(enum tcpc_cc_voltage_status cc1,
 }
 
 /**
+ * Returns true if we detect the port partner is a src debug accessory.
+ */
+static inline int cc_is_src_dbg_acc(enum tcpc_cc_voltage_status cc1,
+	enum tcpc_cc_voltage_status cc2)
+{
+	return cc_is_rp(cc1) && cc_is_rp(cc2);
+}
+
+/**
  * Returns true if the port partner is an audio accessory.
  */
 static inline int cc_is_audio_acc(enum tcpc_cc_voltage_status cc1,