TCPMV2: Default PD Policy Management

A simple implementation to manage PD Policies
on honeybun devices. This is meant as an
interim solution until a more robust solution
is implemented

BUG=b:183026242
BRANCH=none
TEST=make runtests
     Tested on Voxel by plugging in a dock

Signed-off-by: Sam Hurst <shurst@google.com>
Change-Id: Ib8b38754e21b8497fe28855a7f80d2962a4ae7f4
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2774128
Reviewed-by: Yuval Peress <peress@chromium.org>
Reviewed-by: Diana Z <dzigterman@chromium.org>
Commit-Queue: Diana Z <dzigterman@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2821459
Tested-by: Abe Levkoy <alevkoy@chromium.org>
Reviewed-by: Abe Levkoy <alevkoy@chromium.org>
Commit-Queue: Abe Levkoy <alevkoy@chromium.org>

5 files changed, 104 insertions, 18 deletions

diff --git a/common/usbc/build.mk b/common/usbc/build.mk
index 82d9928f8e..48ab5351b8 100644
--- a/common/usbc/build.mk
+++ b/common/usbc/build.mk
@@ -28,6 +28,7 @@ endif # CONFIG_USB_PRL_SM
 ifneq ($(CONFIG_USB_PE_SM),)
 all-obj-$(CONFIG_USB_VPD)+=$(_usbc_dir)usb_pe_ctvpd_sm.o
 all-obj-$(CONFIG_USB_CTVPD)+=$(_usbc_dir)usb_pe_ctvpd_sm.o
+all-obj-$(CONFIG_USB_DRP_ACC_TRYSRC)+=$(_usbc_dir)usbc_pd_policy.o
 all-obj-$(CONFIG_USB_DRP_ACC_TRYSRC)+=$(_usbc_dir)usb_pe_drp_sm.o
 all-obj-$(CONFIG_USB_DRP_ACC_TRYSRC)+=$(_usbc_dir)usb_pd_dpm.o
 all-obj-$(CONFIG_USB_DRP_ACC_TRYSRC)+=$(_usbc_dir)dp_alt_mode.o
@@ -45,5 +46,6 @@ all-obj-$(CONFIG_USB_PD_ALT_MODE_UFP_DP)+=$(_usbc_dir)usb_pd_dp_ufp.o
 endif # CONFIG_USB_PD_TCPMV2
 
 # For testing
+all-obj-$(CONFIG_TEST_USB_PE_SM)+=$(_usbc_dir)usbc_pd_policy.o
 all-obj-$(CONFIG_TEST_USB_PE_SM)+=$(_usbc_dir)usb_pe_drp_sm.o
 all-obj-$(CONFIG_TEST_SM)+=$(_usbc_dir)usb_sm.o
diff --git a/common/usbc/usb_pe_drp_sm.c b/common/usbc/usb_pe_drp_sm.c
index 634df36829..66a5bf4c50 100644
--- a/common/usbc/usb_pe_drp_sm.c
+++ b/common/usbc/usb_pe_drp_sm.c
@@ -23,6 +23,7 @@
 #include "usb_dp_alt_mode.h"
 #include "usb_mode.h"
 #include "usb_pd_dpm.h"
+#include "usb_pd_policy.h"
 #include "usb_pd.h"
 #include "usb_pd_tcpm.h"
 #include "usb_pd_timer.h"
@@ -1806,29 +1807,23 @@ __maybe_unused static bool pe_attempt_port_discovery(int port)
 	if (PE_CHK_FLAG(port, PE_FLAGS_VDM_SETUP_DONE))
 		return false;
 
-	/*
-	 * TODO: POLICY decision: move policy functionality out to a separate
-	 * file.  For now, try once to become DFP/Vconn source
-	 */
-	if (PE_CHK_FLAG(port, PE_FLAGS_DR_SWAP_TO_DFP)) {
+	/* Apply Port Discovery DR Swap Policy */
+	if (port_discovery_dr_swap_policy(port, pe[port].data_role,
+			PE_CHK_FLAG(port, PE_FLAGS_DR_SWAP_TO_DFP))) {
+		PE_SET_FLAG(port, PE_FLAGS_LOCALLY_INITIATED_AMS);
 		PE_CLR_FLAG(port, PE_FLAGS_DR_SWAP_TO_DFP);
-
-		if (pe[port].data_role == PD_ROLE_UFP) {
-			PE_SET_FLAG(port, PE_FLAGS_LOCALLY_INITIATED_AMS);
-			set_state_pe(port, PE_DRS_SEND_SWAP);
-			return true;
-		}
+		set_state_pe(port, PE_DRS_SEND_SWAP);
+		return true;
 	}
 
+	/* Apply Port Discovery VCONN Swap Policy */
 	if (IS_ENABLED(CONFIG_USBC_VCONN) &&
-			PE_CHK_FLAG(port, PE_FLAGS_VCONN_SWAP_TO_ON)) {
+			port_discovery_vconn_swap_policy(port,
+			PE_CHK_FLAG(port, PE_FLAGS_VCONN_SWAP_TO_ON))) {
+		PE_SET_FLAG(port, PE_FLAGS_LOCALLY_INITIATED_AMS);
 		PE_CLR_FLAG(port, PE_FLAGS_VCONN_SWAP_TO_ON);
-
-		if (!tc_is_vconn_src(port)) {
-			PE_SET_FLAG(port, PE_FLAGS_LOCALLY_INITIATED_AMS);
-			set_state_pe(port, PE_VCS_SEND_SWAP);
-			return true;
-		}
+		set_state_pe(port, PE_VCS_SEND_SWAP);
+		return true;
 	}
 
 	/* If mode entry was successful, disable the timer */
diff --git a/common/usbc/usbc_pd_policy.c b/common/usbc/usbc_pd_policy.c
new file mode 100644
index 0000000000..2170734d6a
--- /dev/null
+++ b/common/usbc/usbc_pd_policy.c
@@ -0,0 +1,47 @@
+/* Copyright 2021 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "console.h"
+#include "ec_commands.h"
+#include "usb_pe_sm.h"
+#include "usb_tc_sm.h"
+
+/*
+ * TODO(b:159715784): Implement a more robust solution
+ * to managing PD Policies.
+ */
+
+/*
+ * Default Port Discovery DR Swap Policy.
+ *
+ * 1) If dr_swap_to_dfp_flag == true and port data role is UFP,
+ *    transition to pe_drs_send_swap
+ */
+__overridable bool port_discovery_dr_swap_policy(int port,
+	enum pd_data_role dr, bool dr_swap_flag)
+{
+	if (dr_swap_flag && dr == PD_ROLE_UFP)
+		return true;
+
+	/* Do not perform a DR swap */
+	return false;
+}
+
+/*
+ * Default Port Discovery VCONN Swap Policy.
+ *
+ * 1) If vconn_swap_to_on_flag == true and vconn is currently off,
+ *    transition to pe_vcs_send_swap
+ */
+__overridable bool port_discovery_vconn_swap_policy(int port,
+		bool vconn_swap_flag)
+{
+	if (IS_ENABLED(CONFIG_USBC_VCONN) && vconn_swap_flag &&
+			!tc_is_vconn_src(port))
+		return true;
+
+	/* Do not perform a VCONN swap */
+	return false;
+}
diff --git a/include/usb_pd_policy.h b/include/usb_pd_policy.h
new file mode 100644
index 0000000000..a4f0c64ea6
--- /dev/null
+++ b/include/usb_pd_policy.h
@@ -0,0 +1,41 @@
+/* Copyright 2021 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/* USBC PD Default Policies  */
+
+#ifndef __CROS_EC_USB_PD_POLICY_H
+#define __CROS_EC_USB_PD_POLICY_H
+
+#include "usb_pe_sm.h"
+
+/**
+ * Port Discovery DR Swap Policy
+ *
+ * Different boards can implement its own DR swap policy during a port discovery
+ * by implementing this function.
+ *
+ * @param port USB-C port number
+ * @param dr   current port data role
+ * @param dr_swap_flag   Data Role Swap Flag bit
+ * @param return True if state machine should perform a DR swap, elsf False
+ */
+__override_proto  bool port_discovery_dr_swap_policy(int port,
+		enum pd_data_role dr, bool dr_swap_flag);
+
+/**
+ * Port Discovery VCONN Swap Policy
+ *
+ * Different boards can implement its own VCONN swap policy during a port
+ * discovery by implementing this function.
+ *
+ * @param port USB-C port number
+ * @param vconn_swap_to_on_flag   Vconn Swap to On Flag bit
+ * @param return True if state machine should perform a VCONN swap, elsf False
+ */
+__override_proto bool port_discovery_vconn_swap_policy(int port,
+		bool vconn_swap_flag);
+
+#endif /* __CROS_EC_USB_PD_POLICY_H */
+
diff --git a/zephyr/CMakeLists.txt b/zephyr/CMakeLists.txt
index 2830be499b..46747fed5a 100644
--- a/zephyr/CMakeLists.txt
+++ b/zephyr/CMakeLists.txt
@@ -219,6 +219,7 @@ zephyr_sources_ifdef(CONFIG_PLATFORM_EC_USB_DRP_ACC_TRYSRC
                                                 "${PLATFORM_EC}/common/usbc/usb_tc_drp_acc_trysrc_sm.c"
                                                 "${PLATFORM_EC}/common/usbc/usb_pe_drp_sm.c"
                                                 "${PLATFORM_EC}/common/usbc/usb_pd_dpm.c"
+						"${PLATFORM_EC}/common/usbc/usbc_pd_policy.c"
                                                 "${PLATFORM_EC}/common/usbc/dp_alt_mode.c")
 
 zephyr_sources_ifdef(CONFIG_PLATFORM_EC_USB_PRL_SM