partner emul: Optionally reject DR_Swap

Support runtime configuration of the partner emulator to Reject a Data
Role Swap based on the new role of the partner emulator.

BUG=b:271613370
TEST=twister -s drivers/drivers.usbc_alt_mode
BRANCH=none

Change-Id: I47a6b99d334d083ad0d9e40b211507a4e21248b3
Signed-off-by: Abe Levkoy <alevkoy@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/4334627
Reviewed-by: Diana Z <dzigterman@chromium.org>

2 files changed, 39 insertions, 2 deletions

diff --git a/zephyr/emul/tcpc/emul_tcpci_partner_common.c b/zephyr/emul/tcpc/emul_tcpci_partner_common.c
index 7a1670fe0e..e7be6250b6 100644
--- a/zephyr/emul/tcpc/emul_tcpci_partner_common.c
+++ b/zephyr/emul/tcpc/emul_tcpci_partner_common.c
@@ -5,6 +5,7 @@
 
 #include "common.h"
 #include "driver/tcpm/tcpci.h"
+#include "ec_commands.h"
 #include "emul/tcpc/emul_tcpci.h"
 #include "emul/tcpc/emul_tcpci_partner_common.h"
 #include "usb_pd.h"
@@ -957,8 +958,14 @@ void tcpci_partner_common_swap_data_role(struct tcpci_partner_data *data)
 static enum tcpci_partner_handler_res
 tcpci_partner_common_dr_swap_handler(struct tcpci_partner_data *data)
 {
-	tcpci_partner_send_control_msg(data, PD_CTRL_ACCEPT, 0);
-	tcpci_partner_common_swap_data_role(data);
+	enum pd_ctrl_msg_type response = PD_CTRL_REJECT;
+
+	if ((data->data_role == PD_ROLE_DFP && data->drs_to_ufp_supported) ||
+	    (data->data_role == PD_ROLE_UFP && data->drs_to_dfp_supported))
+		response = PD_CTRL_ACCEPT;
+	tcpci_partner_send_control_msg(data, response, 0);
+	if (response == PD_CTRL_ACCEPT)
+		tcpci_partner_common_swap_data_role(data);
 
 	return TCPCI_PARTNER_COMMON_MSG_HANDLED;
 }
@@ -1642,6 +1649,8 @@ void tcpci_partner_init(struct tcpci_partner_data *data, enum pd_rev_type rev)
 	data->send_goodcrc = true;
 
 	data->rev = rev;
+	data->drs_to_dfp_supported = true;
+	data->drs_to_ufp_supported = true;
 	data->vconn_supported = true;
 
 	data->ops.transmit = tcpci_partner_transmit_op;
@@ -1659,6 +1668,14 @@ void tcpci_partner_init(struct tcpci_partner_data *data, enum pd_rev_type rev)
 	data->cable = NULL;
 }
 
+void tcpci_partner_set_drs_support(struct tcpci_partner_data *data,
+				   bool drs_to_ufp_supported,
+				   bool drs_to_dfp_supported)
+{
+	data->drs_to_ufp_supported = drs_to_ufp_supported;
+	data->drs_to_dfp_supported = drs_to_dfp_supported;
+}
+
 void tcpci_partner_set_vconn_support(struct tcpci_partner_data *data,
 				     bool vconn_supported)
 {
diff --git a/zephyr/include/emul/tcpc/emul_tcpci_partner_common.h b/zephyr/include/emul/tcpc/emul_tcpci_partner_common.h
index 91e7d057f5..7a8c69076b 100644
--- a/zephyr/include/emul/tcpc/emul_tcpci_partner_common.h
+++ b/zephyr/include/emul/tcpc/emul_tcpci_partner_common.h
@@ -76,6 +76,14 @@ struct tcpci_partner_data {
 	enum pd_power_role power_role;
 	/** Data role (used in message header) */
 	enum pd_data_role data_role;
+	/** Whether this partner will Accept a Data Role Swap that would switch
+	 * the partner from DFP to UFP.
+	 */
+	bool drs_to_ufp_supported;
+	/** Whether this partner will Accept a Data Role Swap that would switch
+	 * the partner from UFP to DFP.
+	 */
+	bool drs_to_dfp_supported;
 	/** VCONN role */
 	enum pd_vconn_role vconn_role;
 	/** Revision (used in message header) */
@@ -356,6 +364,18 @@ struct tcpci_partner_extension_ops {
 void tcpci_partner_init(struct tcpci_partner_data *data, enum pd_rev_type rev);
 
 /**
+ * @brief Set the partner emulator to support or not support swapping data roles
+ * to UFP and DFP. If the partner supports a swap, it should respond to DR_Swap
+ * with Accept with that role as the new data role.
+ *
+ * @param data Pointer to USB-C partner emulator
+ * @param drs_to_ufp_supported Whether the partner supports swapping to UFP
+ * @param drs_to_dfp_supported Whether the partner supports swapping to DFP
+ */
+void tcpci_partner_set_drs_support(struct tcpci_partner_data *data,
+				   bool drs_to_ufp_supported,
+				   bool drs_to_dfp_supported);
+/**
  * @brief Set the partner emulator to support or not support sourcing VCONN. If
  * the partner supports VCONN, it should respond to VCONN Swap with Accept,
  * Reject, or Wait. If it does not support VCONN, it should respond with