pd: Enable USB PD SOP' and SOP'' Communication

Currently, the PD stack ignores messages received from SOP' and SOP'' and
this prevents the stack from communicating with VCONN Power Devices and
Cable Plugs in general.

I propose encoding the message address (SOP*) in the message header. The
message header is encoded as a 16-bit value but the TCPC drivers use a
32-bit type for the header.

The SOP* address will be stored in bits 31 to 28 of the message header
and the PD stack can check those bits to determine the address of the
message.

BUG=b:122109575
BRANCH=none
TEST=manual

Change-Id: I2b34c16cae186202c9cf0bc5f940e05151e88cbf
Signed-off-by: Sam Hurst <shurst@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1390951
Commit-Ready: ChromeOS CL Exonerator Bot <chromiumos-cl-exonerator@appspot.gserviceaccount.com>
Tested-by: Sam Hurst <shurst@google.com>
Reviewed-by: Jett Rink <jettrink@chromium.org>

1 files changed, 44 insertions, 5 deletions

diff --git a/common/usb_pd_tcpc.c b/common/usb_pd_tcpc.c
index 3e79569e2e..0feabb5b10 100644
--- a/common/usb_pd_tcpc.c
+++ b/common/usb_pd_tcpc.c
@@ -202,6 +202,12 @@ enum pd_tx_errors {
 	PD_TX_ERR_COLLISION = -5 /* Collision detected during transmit */
 };
 
+/* PD Header with SOP* encoded in bits 31 - 28 */
+union pd_header_sop {
+	uint16_t pd_header;
+	uint32_t head;
+};
+
 /*
  * If TCPM is not on this chip, and PD low power is defined, then use low
  * power task delay logic.
@@ -626,7 +632,7 @@ int pd_analyze_rx(int port, uint32_t *payload)
 	int bit;
 	char *msg = "---";
 	uint32_t val = 0;
-	uint16_t header;
+	union pd_header_sop phs;
 	uint32_t pcrc, ccrc;
 	int p, cnt;
 	uint32_t eop;
@@ -646,6 +652,11 @@ int pd_analyze_rx(int port, uint32_t *payload)
 	/* Find the Start Of Packet sequence */
 	while (bit > 0) {
 		bit = pd_dequeue_bits(port, bit, 20, &val);
+#ifdef CONFIG_USB_PD_DECODE_SOP
+		if (val == PD_SOP || val == PD_SOP_PRIME ||
+						val == PD_SOP_PRIME_PRIME)
+			break;
+#else
 		if (val == PD_SOP) {
 			break;
 		} else if (val == PD_SOP_PRIME) {
@@ -655,22 +666,50 @@ int pd_analyze_rx(int port, uint32_t *payload)
 			CPRINTF("SOP''\n");
 			return PD_RX_ERR_UNSUPPORTED_SOP;
 		}
+#endif
 	}
 	if (bit < 0) {
+#ifdef CONFIG_USB_PD_DECODE_SOP
+		if (val == PD_SOP)
+			msg = "SOP";
+		else if (val == PD_SOP_PRIME)
+			msg = "SOP'";
+		else if (val == PD_SOP_PRIME_PRIME)
+			msg = "SOP''";
+		else
+			msg = "SOP*";
+#else
 		msg = "SOP";
+#endif
 		goto packet_err;
 	}
 
+	phs.head = 0;
+
 	/* read header */
-	bit = decode_short(port, bit, &header);
+	bit = decode_short(port, bit, &phs.pd_header);
 
 #ifdef CONFIG_COMMON_RUNTIME
 	mutex_lock(&pd_crc_lock);
 #endif
 
 	crc32_init();
-	crc32_hash16(header);
-	cnt = PD_HEADER_CNT(header);
+	crc32_hash16(phs.pd_header);
+	cnt = PD_HEADER_CNT(phs.pd_header);
+
+#ifdef CONFIG_USB_PD_DECODE_SOP
+	/* Encode message address */
+	if (val == PD_SOP) {
+		phs.head |= PD_HEADER_SOP(PD_MSG_SOP);
+	} else if (val == PD_SOP_PRIME) {
+		phs.head |= PD_HEADER_SOP(PD_MSG_SOPP);
+	} else if (val == PD_SOP_PRIME_PRIME) {
+		phs.head |= PD_HEADER_SOP(PD_MSG_SOPPP);
+	} else {
+		msg = "SOP*";
+		goto packet_err;
+	}
+#endif
 
 	/* read payload data */
 	for (p = 0; p < cnt && bit > 0; p++) {
@@ -710,7 +749,7 @@ int pd_analyze_rx(int port, uint32_t *payload)
 		goto packet_err;
 	}
 
-	return header;
+	return phs.head;
 packet_err:
 	if (debug_level >= 2)
 		pd_dump_packet(port, msg);