pd_policy: Change DP AltMode event from host event to MKBP.

Previously, the EC could notify the AP that it had entered into
DisplayPort Alternate mode by sending a MODE_CHANGE host event.
However, there was no mechanism to disable that functionality if desired
without effecting the other MODE_CHANGE events (i.e. - base
attach/detach).  By changing the DisplayPort Alternate mode entry to an
MKBP event, we can have more granularity and only affect this single
event.

- This commit adds a new MKBP event, EC_MKBP_EVENT_DP_ALT_MODE_ENTERED.
- The commit also changes the DP AltMode entry notification from sending
  a MODE_CHANGE host event to this new MKBP event.

BUG=chromium:786721
BRANCH=None
TEST=Build and flash nocturne, verify that system still wakes up on
DisplayPort Alternate Mode entry.

Change-Id: Ia5f294b26701c3c98c9b7f948fc693d26234c835
Signed-off-by: Aseda Aboagye <aaboagye@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1685787
Tested-by: Aseda Aboagye <aaboagye@chromium.org>
Commit-Queue: Aseda Aboagye <aaboagye@chromium.org>
Reviewed-by: Alexandru M Stan <amstan@chromium.org>

3 files changed, 16 insertions, 14 deletions

diff --git a/common/usb_pd_policy.c b/common/usb_pd_policy.c
index d5e0a6e65a..20fc8559af 100644
--- a/common/usb_pd_policy.c
+++ b/common/usb_pd_policy.c
@@ -7,10 +7,12 @@
 #include "charge_manager.h"
 #include "common.h"
 #include "console.h"
+#include "ec_commands.h"
 #include "flash.h"
 #include "gpio.h"
 #include "hooks.h"
 #include "host_command.h"
+#include "mkbp_event.h"
 #include "registers.h"
 #include "rsa.h"
 #include "sha256.h"
@@ -34,22 +36,20 @@
 
 static int rw_flash_changed = 1;
 
-#ifdef CONFIG_HOSTCMD_EVENTS
+#ifdef CONFIG_MKBP_EVENT
+static int dp_alt_mode_entry_get_next_event(uint8_t *data)
+{
+	return EC_SUCCESS;
+}
+DECLARE_EVENT_SOURCE(EC_MKBP_EVENT_DP_ALT_MODE_ENTERED,
+		     dp_alt_mode_entry_get_next_event);
+
 void pd_notify_dp_alt_mode_entry(void)
 {
-	/*
-	 * Note: EC_HOST_EVENT_PD_MCU may be a more appropriate host event to
-	 * send, but we do not send that here because there are other cases
-	 * where we send EC_HOST_EVENT_PD_MCU such as charger insertion or
-	 * removal.  Currently, those do not wake the system up, but
-	 * EC_HOST_EVENT_MODE_CHANGE does.  If we made the system wake up on
-	 * EC_HOST_EVENT_PD_MCU, we would be turning the internal display on on
-	 * every charger insertion/removal, which is not desired.
-	 */
 	CPRINTS("Notifying AP of DP Alt Mode Entry...");
-	host_set_single_event(EC_HOST_EVENT_MODE_CHANGE);
+	mkbp_send_event(EC_MKBP_EVENT_DP_ALT_MODE_ENTERED);
 }
-#endif /* CONFIG_HOSTCMD_EVENTS */
+#endif /* CONFIG_MKBP_EVENT */
 
 int pd_check_requested_voltage(uint32_t rdo, const int port)
 {
diff --git a/include/ec_commands.h b/include/ec_commands.h
index fdcab353e0..5e78cae51c 100644
--- a/include/ec_commands.h
+++ b/include/ec_commands.h
@@ -622,7 +622,6 @@ enum host_event_code {
 	 *
 	 * - TABLET/LAPTOP mode
 	 * - detachable base attach/detach event
-	 * - DisplayPort Alternate Mode entry
 	 */
 	EC_HOST_EVENT_MODE_CHANGE = 29,
 
@@ -3472,6 +3471,9 @@ enum ec_mkbp_event {
 	/* Send an incoming CEC message to the AP */
 	EC_MKBP_EVENT_CEC_MESSAGE = 9,
 
+	/* We have entered DisplayPort Alternate Mode on a Type-C port. */
+	EC_MKBP_EVENT_DP_ALT_MODE_ENTERED = 10,
+
 	/* Number of MKBP events */
 	EC_MKBP_EVENT_COUNT,
 };
diff --git a/include/usb_pd.h b/include/usb_pd.h
index 3dba8483d0..5cd7eb8851 100644
--- a/include/usb_pd.h
+++ b/include/usb_pd.h
@@ -1993,7 +1993,7 @@ int pd_is_debug_acc(int port);
 
 /*
  * Notify the AP that we have entered into DisplayPort Alternate Mode.  This
- * sets a MODE_CHANGE host event which may wake the AP.
+ * sets a DP_ALT_MODE_ENTERED MKBP event which may wake the AP.
  */
 void pd_notify_dp_alt_mode_entry(void);