TCPMv2: Add DPM setup enum

Currently, the functions to set up VDMs return a VDO count to indicate
success versus an error.  They also have a return of 0, which isn't
strictly defined in the documentation, but is used as an indication a
mode isn't supported in the TBT module at least.

Add a descriptive enum to indicate whether the module set up a message
successfully, has an unsupported mode, or encountered an error.  These
should track roughly to the old positive, zero, and -1 values.

BRANCH=None
BUG=None
TEST=tast typec.Mode*.manual on voxel

Signed-off-by: Diana Z <dzigterman@chromium.org>
Change-Id: I05fe0ccc5f39e433dd4fbc39c97278b3c1542497
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3192235
Reviewed-by: Abe Levkoy <alevkoy@chromium.org>

6 files changed, 89 insertions, 53 deletions

diff --git a/common/usbc/dp_alt_mode.c b/common/usbc/dp_alt_mode.c
index 9a3493c6e1..ecade62773 100644
--- a/common/usbc/dp_alt_mode.c
+++ b/common/usbc/dp_alt_mode.c
@@ -207,14 +207,15 @@ void dp_vdm_naked(int port, enum tcpci_msg_type type, uint8_t vdm_cmd)
 	}
 }
 
-int dp_setup_next_vdm(int port, int vdo_count, uint32_t *vdm)
+enum dpm_msg_setup_status dp_setup_next_vdm(int port, int *vdo_count,
+					    uint32_t *vdm)
 {
 	const struct svdm_amode_data *modep = pd_get_amode_data(port,
 			TCPCI_MSG_SOP, USB_SID_DISPLAYPORT);
 	int vdo_count_ret;
 
-	if (vdo_count < VDO_MAX_SIZE)
-		return -1;
+	if (*vdo_count < VDO_MAX_SIZE)
+		return MSG_SETUP_ERROR;
 
 	switch (dp_state[port]) {
 	case DP_START:
@@ -223,7 +224,7 @@ int dp_setup_next_vdm(int port, int vdo_count, uint32_t *vdm)
 		vdm[0] = pd_dfp_enter_mode(port, TCPCI_MSG_SOP,
 				USB_SID_DISPLAYPORT, 0);
 		if (vdm[0] == 0)
-			return -1;
+			return MSG_SETUP_ERROR;
 		/* CMDT_INIT is 0, so this is a no-op */
 		vdm[0] |= VDO_CMDT(CMDT_INIT);
 		vdm[0] |= VDO_SVDM_VERS(pd_get_vdo_ver(port, TCPCI_MSG_SOP));
@@ -233,22 +234,22 @@ int dp_setup_next_vdm(int port, int vdo_count, uint32_t *vdm)
 		break;
 	case DP_ENTER_ACKED:
 		if (!(modep && modep->opos))
-			return -1;
+			return MSG_SETUP_ERROR;
 
 		vdo_count_ret = modep->fx->status(port, vdm);
 		if (vdo_count_ret == 0)
-			return -1;
+			return MSG_SETUP_ERROR;
 		vdm[0] |= PD_VDO_OPOS(modep->opos);
 		vdm[0] |= VDO_CMDT(CMDT_INIT);
 		vdm[0] |= VDO_SVDM_VERS(pd_get_vdo_ver(port, TCPCI_MSG_SOP));
 		break;
 	case DP_STATUS_ACKED:
 		if (!(modep && modep->opos))
-			return -1;
+			return MSG_SETUP_ERROR;
 
 		vdo_count_ret = modep->fx->config(port, vdm);
 		if (vdo_count_ret == 0)
-			return -1;
+			return MSG_SETUP_ERROR;
 		vdm[0] |= VDO_CMDT(CMDT_INIT);
 		vdm[0] |= VDO_SVDM_VERS(pd_get_vdo_ver(port, TCPCI_MSG_SOP));
 		break;
@@ -265,7 +266,7 @@ int dp_setup_next_vdm(int port, int vdo_count, uint32_t *vdm)
 		 * TODO(b/159856063): Clean up the API to the fx functions.
 		 */
 		if (!(modep && modep->opos))
-			return -1;
+			return MSG_SETUP_ERROR;
 
 		usb_mux_set_safe_mode_exit(port);
 
@@ -282,11 +283,17 @@ int dp_setup_next_vdm(int port, int vdo_count, uint32_t *vdm)
 		/*
 		 * DP mode is inactive.
 		 */
-		return -1;
+		return MSG_SETUP_ERROR;
 	default:
 		CPRINTF("%s called with invalid state %d\n",
 				__func__, dp_state[port]);
-		return -1;
+		return MSG_SETUP_ERROR;
 	}
-	return vdo_count_ret;
+
+	if (vdo_count_ret) {
+		*vdo_count = vdo_count_ret;
+		return MSG_SETUP_SUCCESS;
+	}
+
+	return MSG_SETUP_UNSUPPORTED;
 }
diff --git a/common/usbc/tbt_alt_mode.c b/common/usbc/tbt_alt_mode.c
index 73e2796345..eb64519c1e 100644
--- a/common/usbc/tbt_alt_mode.c
+++ b/common/usbc/tbt_alt_mode.c
@@ -458,8 +458,9 @@ static bool tbt_mode_is_supported(int port, int vdo_count)
 	return true;
 }
 
-int tbt_setup_next_vdm(int port, int vdo_count, uint32_t *vdm,
-		enum tcpci_msg_type *tx_type)
+enum dpm_msg_setup_status tbt_setup_next_vdm(int port, int *vdo_count,
+					     uint32_t *vdm,
+					     enum tcpci_msg_type *tx_type)
 {
 	struct svdm_amode_data *modep;
 	int vdo_count_ret = 0;
@@ -467,13 +468,13 @@ int tbt_setup_next_vdm(int port, int vdo_count, uint32_t *vdm,
 
 	*tx_type = TCPCI_MSG_SOP;
 
-	if (vdo_count < VDO_MAX_SIZE)
-		return -1;
+	if (*vdo_count < VDO_MAX_SIZE)
+		return MSG_SETUP_ERROR;
 
 	switch (tbt_state[port]) {
 	case TBT_START:
-		if (!tbt_mode_is_supported(port, vdo_count))
-			return 0;
+		if (!tbt_mode_is_supported(port, *vdo_count))
+			return MSG_SETUP_UNSUPPORTED;
 
 		if (!TBT_CHK_FLAG(port, TBT_FLAG_RETRY_DONE))
 			tbt_prints("attempt to enter mode", port);
@@ -523,7 +524,7 @@ int tbt_setup_next_vdm(int port, int vdo_count, uint32_t *vdm,
 		modep = pd_get_amode_data(port,
 					  TCPCI_MSG_SOP, USB_VID_INTEL);
 		if (!(modep && modep->opos))
-			return -1;
+			return MSG_SETUP_ERROR;
 
 		usb_mux_set_safe_mode_exit(port);
 
@@ -538,7 +539,7 @@ int tbt_setup_next_vdm(int port, int vdo_count, uint32_t *vdm,
 		modep = pd_get_amode_data(port,
 			TCPCI_MSG_SOP_PRIME, USB_VID_INTEL);
 		if (!(modep && modep->opos))
-			return -1;
+			return MSG_SETUP_ERROR;
 
 		usb_mux_set_safe_mode_exit(port);
 
@@ -554,7 +555,7 @@ int tbt_setup_next_vdm(int port, int vdo_count, uint32_t *vdm,
 		modep = pd_get_amode_data(port,
 				TCPCI_MSG_SOP_PRIME, USB_VID_INTEL);
 		if (!(modep && modep->opos))
-			return -1;
+			return MSG_SETUP_ERROR;
 
 		usb_mux_set_safe_mode_exit(port);
 
@@ -568,12 +569,17 @@ int tbt_setup_next_vdm(int port, int vdo_count, uint32_t *vdm,
 		break;
 	case TBT_INACTIVE:
 		/* Thunderbolt mode is inactive */
-		return 0;
+		return MSG_SETUP_UNSUPPORTED;
 	default:
 		 CPRINTF("%s called with invalid state %d\n",
 				__func__, tbt_state[port]);
-		return -1;
+		return MSG_SETUP_ERROR;
 	}
 
-	return vdo_count_ret;
+	if (vdo_count_ret) {
+		*vdo_count = vdo_count_ret;
+		return MSG_SETUP_SUCCESS;
+	}
+
+	return MSG_SETUP_UNSUPPORTED;
 }
diff --git a/common/usbc/usb_pd_dpm.c b/common/usbc/usb_pd_dpm.c
index 5053f0a482..3e399489b2 100644
--- a/common/usbc/usb_pd_dpm.c
+++ b/common/usbc/usb_pd_dpm.c
@@ -235,6 +235,7 @@ static void dpm_attempt_mode_entry(int port)
 	enum tcpci_msg_type tx_type = TCPCI_MSG_SOP;
 	bool enter_mode_requested =
 		IS_ENABLED(CONFIG_USB_PD_REQUIRE_AP_MODE_ENTRY) ?  false : true;
+	enum dpm_msg_setup_status status = MSG_SETUP_UNSUPPORTED;
 
 	if (pd_get_data_role(port) != PD_ROLE_DFP) {
 		if (DPM_CHK_FLAG(port, DPM_FLAG_ENTER_DP |
@@ -288,8 +289,9 @@ static void dpm_attempt_mode_entry(int port)
 		 * cable and USB4 mode with the port partner.
 		 */
 		if (tbt_cable_entry_required_for_usb4(port)) {
-			vdo_count = tbt_setup_next_vdm(port,
-				ARRAY_SIZE(vdm), vdm, &tx_type);
+			vdo_count = ARRAY_SIZE(vdm);
+			status = tbt_setup_next_vdm(port, &vdo_count, vdm,
+						    &tx_type);
 		} else {
 			pd_dpm_request(port, DPM_REQUEST_ENTER_USB);
 			return;
@@ -303,24 +305,28 @@ static void dpm_attempt_mode_entry(int port)
 				USB_VID_INTEL) &&
 			dpm_mode_entry_requested(port, TYPEC_MODE_TBT)) {
 		enter_mode_requested = true;
-		vdo_count = tbt_setup_next_vdm(port,
-			ARRAY_SIZE(vdm), vdm, &tx_type);
+		vdo_count = ARRAY_SIZE(vdm);
+		status = tbt_setup_next_vdm(port, &vdo_count, vdm,
+					    &tx_type);
 	}
 
 	/* If not, check if they support DisplayPort alt mode. */
-	if (vdo_count == 0 && !DPM_CHK_FLAG(port, DPM_FLAG_MODE_ENTRY_DONE) &&
+	if (status == MSG_SETUP_UNSUPPORTED &&
+	    !DPM_CHK_FLAG(port, DPM_FLAG_MODE_ENTRY_DONE) &&
 	    pd_is_mode_discovered_for_svid(port, TCPCI_MSG_SOP,
-				USB_SID_DISPLAYPORT) &&
+					   USB_SID_DISPLAYPORT) &&
 	    dpm_mode_entry_requested(port, TYPEC_MODE_DP)) {
 		enter_mode_requested = true;
-		vdo_count = dp_setup_next_vdm(port, ARRAY_SIZE(vdm), vdm);
+		vdo_count = ARRAY_SIZE(vdm);
+		status = dp_setup_next_vdm(port, &vdo_count, vdm);
 	}
 
 	/*
 	 * If the PE didn't discover any supported (requested) alternate mode,
 	 * just mark setup done and get out of here.
 	 */
-	if (vdo_count == 0 && !DPM_CHK_FLAG(port, DPM_FLAG_MODE_ENTRY_DONE)) {
+	if (status != MSG_SETUP_SUCCESS &&
+				!DPM_CHK_FLAG(port, DPM_FLAG_MODE_ENTRY_DONE)) {
 		if (enter_mode_requested) {
 			/*
 			 * TODO(b/168030639): Notify the AP that mode entry
@@ -336,7 +342,7 @@ static void dpm_attempt_mode_entry(int port)
 		return;
 	}
 
-	if (vdo_count < 0) {
+	if (status != MSG_SETUP_SUCCESS) {
 		dpm_set_mode_entry_done(port);
 		CPRINTS("C%d: Couldn't construct alt mode VDM", port);
 		return;
@@ -356,8 +362,9 @@ static void dpm_attempt_mode_entry(int port)
 
 static void dpm_attempt_mode_exit(int port)
 {
-	uint32_t vdm = 0;
-	int vdo_count = 0;
+	uint32_t vdm[VDO_MAX_SIZE];
+	int vdo_count = ARRAY_SIZE(vdm);
+	enum dpm_msg_setup_status status = MSG_SETUP_ERROR;
 	enum tcpci_msg_type tx_type = TCPCI_MSG_SOP;
 
 	if (IS_ENABLED(CONFIG_USB_PD_USB4) &&
@@ -374,18 +381,20 @@ static void dpm_attempt_mode_exit(int port)
 		 */
 		CPRINTS("C%d: TBT teardown", port);
 		tbt_exit_mode_request(port);
-		vdo_count = tbt_setup_next_vdm(port, VDO_MAX_SIZE, &vdm,
-					&tx_type);
+		status = tbt_setup_next_vdm(port, &vdo_count, vdm, &tx_type);
 	} else if (dp_is_active(port)) {
 		CPRINTS("C%d: DP teardown", port);
-		vdo_count = dp_setup_next_vdm(port, VDO_MAX_SIZE, &vdm);
+		status = dp_setup_next_vdm(port, &vdo_count, vdm);
 	} else {
 		/* Clear exit mode request */
 		dpm_clear_mode_exit_request(port);
 		return;
 	}
 
-	if (!pd_setup_vdm_request(port, tx_type, &vdm, vdo_count)) {
+	if (status != MSG_SETUP_SUCCESS)
+		return;
+
+	if (!pd_setup_vdm_request(port, tx_type, vdm, vdo_count)) {
 		dpm_clear_mode_exit_request(port);
 		return;
 	}
diff --git a/include/usb_dp_alt_mode.h b/include/usb_dp_alt_mode.h
index ea824ea476..40b7c321dd 100644
--- a/include/usb_dp_alt_mode.h
+++ b/include/usb_dp_alt_mode.h
@@ -15,6 +15,7 @@
 #include <stdint.h>
 
 #include "tcpm/tcpm.h"
+#include "usb_pd_dpm.h"
 
 /*
  * Initialize DP state for the specified port.
@@ -66,12 +67,14 @@ void dp_vdm_naked(int port, enum tcpci_msg_type type, uint8_t vdm_cmd);
 /*
  * Construct the next DisplayPort VDM that should be sent.
  *
- * @param port      USB-C port number
- * @param vdo_count The number of VDOs in vdm; must be at least VDO_MAX_SIZE
- * @param vdm       The VDM payload to be sent; output; must point to at least
- *                  VDO_MAX_SIZE elements
- * @return          The number of VDOs written to VDM or -1 to indicate error
+ * @param[in] port	    USB-C port number
+ * @param[in,out] vdo_count The number of VDOs in vdm; must be at least
+ *			    VDO_MAX_SIZE.  On success, number of populated VDOs
+ * @param[out] vdm          The VDM payload to be sent; output; must point to at
+ *			    least VDO_MAX_SIZE elements
+ * @return		    enum dpm_msg_setup_status
  */
-int dp_setup_next_vdm(int port, int vdo_count, uint32_t *vdm);
+enum dpm_msg_setup_status dp_setup_next_vdm(int port, int *vdo_count,
+					    uint32_t *vdm);
 
 #endif  /* __CROS_EC_USB_DP_ALT_MODE_H */
diff --git a/include/usb_pd_dpm.h b/include/usb_pd_dpm.h
index 19d4c4fe6b..4a389b2116 100644
--- a/include/usb_pd_dpm.h
+++ b/include/usb_pd_dpm.h
@@ -108,4 +108,11 @@ int dpm_get_source_pdo(const uint32_t **src_pdo, const int port);
  */
 int dpm_get_source_current(const int port);
 
+/* Enum for modules to describe to the DPM their setup status */
+enum dpm_msg_setup_status {
+	MSG_SETUP_SUCCESS,
+	MSG_SETUP_ERROR,
+	MSG_SETUP_UNSUPPORTED,
+};
+
 #endif  /* __CROS_EC_USB_DPM_H */
diff --git a/include/usb_tbt_alt_mode.h b/include/usb_tbt_alt_mode.h
index 1ea4828059..a187c1b42b 100644
--- a/include/usb_tbt_alt_mode.h
+++ b/include/usb_tbt_alt_mode.h
@@ -14,6 +14,7 @@
 #include <stdint.h>
 
 #include "tcpm/tcpm.h"
+#include "usb_pd_dpm.h"
 #include "usb_pd_tcpm.h"
 
 /*
@@ -92,14 +93,17 @@ void intel_vdm_naked(int port, enum tcpci_msg_type type, uint8_t vdm_cmd);
 /*
  * Construct the next Thunderbolt VDM that should be sent.
  *
- * @param port      USB-C port number
- * @param vdo_count The number of VDOs in vdm; must be at least VDO_MAX_SIZE
- * @param vdm       The VDM payload to be sent; output; must point to at least
- *                  VDO_MAX_SIZE elements
- * @param tx_type   Transmit type(SOP, SOP', SOP'') for next VDM to be sent
- * @return          The number of VDOs written to VDM or -1 to indicate error
+ * @param[in] port          USB-C port number
+ * @param[in,out] vdo_count The number of VDOs in vdm; must be at least
+ *		            VDO_MAX_SIZE.  Filled with VDOs populated on success
+ * @param[out] vdm          The VDM payload to be sent; output; must point to at
+ *			    least VDO_MAX_SIZE elements
+ * @param[out] tx_type	    Transmit type(SOP, SOP', SOP'') for next VDM to be
+ *			    sent
+ * @return		    enum dpm_msg_setup_status
  */
-int tbt_setup_next_vdm(int port, int vdo_count, uint32_t *vdm,
-		enum tcpci_msg_type *tx_type);
+enum dpm_msg_setup_status tbt_setup_next_vdm(int port, int *vdo_count,
+					     uint32_t *vdm,
+					     enum tcpci_msg_type *tx_type);
 
 #endif