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>

1 files changed, 44 insertions, 0 deletions

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,