control UART_EC RX/TX based on EC-CR50 communication status

This patch allows EC-CR50 communication to enable EC UART only
if EC is on and bitbang mode is disabled. EC UART shall be enabled
even when CCD_CAP_GSC_TX_EC_RX is disabled, EC UART is ccdblocked,
or servo is connected. EC-CR50 comm supporting boards are supposed
to have H1 dominate EC UART TX line against servo.

Servo detection, which is checked every second, shall be delayed
during EC-CR50 communication because EC UART TX pin
(GPIO_SERVO_DETECT) is used as an output. Servo state shall be
held as it was. Once EC-CR50 communication is done, the servo
detection will resume or CCD state gets updated based on what
it used to be before EC-CR50 communication.

BUG=chromium:1035706
BRANCH=cr50
TEST=manually tested on a reworked Helios.

// CCD connection only
> ccdstate
AP:      off
AP UART: off
EC:      on
Rdd:     connected
Servo:   undetectable
CCD EXT: enabled
State flags: UARTEC+TX I2C SPI
CCD ports blocked: (none)
> ecrst pulse
Pulsing EC reset
EC_RST_L is deasserted

// Servo connection only
> ccdstate
AP:      off
AP UART: off
EC:      on
Rdd:     disconnected
Servo:   connected
CCD EXT: disabled
State flags: I2C
CCD ports blocked: (none)

Change-Id: I02667bee004d237d846393a18f247970982c71b7
Signed-off-by: Namyoon Woo <namyoon@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2023239
Reviewed-by: Vadim Bendebury <vbendeb@chromium.org>

0 files changed, 0 insertions, 0 deletions