Adds the `google_chromeec_ap_poweroff()` helper function to the ChromeEC
driver.
This new API wraps the `EC_CMD_AP_SHUTDOWN` command and sends it to the
Embedded Controller (EC). This provides a cleaner, standardized way for
other coreboot components to initiate an Application Processor (AP)
power-off sequence via the EC.
After sending the shutdown command, the function calls `halt()` as the
AP is expected to power down immediately after the EC processes the
command.
BUG=b:439819922
TEST=Verify shutdown on Google/Quenbi.
Change-Id: Iace6a66972791bb7acdb978dfeea67b6ff0fec68
Signed-off-by: Kapil Porwal <kapilporwal@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/89223
Reviewed-by: Caveh Jalali <caveh@chromium.org>
Reviewed-by: Subrata Banik <subratabanik@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
0d4c0ee7fc