cr50: Update to VENDOR_CC_GET_PWR_BTN

Change the VENDOR_CC_GET_PWR_BTN behavior to report the live state of
the power button.  On Wilco devices, the AP needs to poll for both a
power button press and release prior to booting an untrusted OS.

The falling edge of the power button is still latched, so the first call
to VENDOR_CC_GET_PWR_BTN command will return a button state of 1 if this
call is made within 10 seconds.  Once the latched state is clear,
VENDOR_CC_GET_PWR_BTN returns the live state of the power button.

BUG=b:128431787
BRANCH=cr50
TEST=Added test code into vboot recovery screen to poll
VENDOR_CC_GET_PWR_BTN command for a power button press and a power
button release.

Change-Id: I8bc34e4e6309f6b3bd8020655370eb50032a00f1
Signed-off-by: Keith Short <keithshort@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1534337
Reviewed-by: Mary Ruthven <mruthven@chromium.org>
Reviewed-by: Matt Delco <delco@google.com>

1 files changed, 12 insertions, 1 deletions

diff --git a/board/cr50/power_button.c b/board/cr50/power_button.c
index 83379ae167..5f46a4d0a6 100644
--- a/board/cr50/power_button.c
+++ b/board/cr50/power_button.c
@@ -140,7 +140,18 @@ static enum vendor_cmd_rc vc_get_pwr_btn(enum vendor_cmd_cc code,
 					 size_t input_size,
 					 size_t *response_size)
 {
-	if (pop_check_presence(1) == POP_TOUCH_YES)
+	/*
+	 * The AP uses VENDOR_CC_GET_PWR_BTN to poll both for the press and
+	 * release of the power button.
+	 *
+	 * pop_check_presence(1) returns true if a new power button press was
+	 * recorded in the last 10 seconds.
+	 *
+	 * Indicate button release if no new presses have been recorded and the
+	 * current button state is not pressed.
+	 */
+	if (pop_check_presence(1) == POP_TOUCH_YES ||
+		rbox_powerbtn_is_pressed())
 		*(uint8_t *)buf = 1;
 	else
 		*(uint8_t *)buf = 0;