pd: Limit input current to 500mA on PD voltage transition

Upon requesting a PD power contract at a new voltage, keep the input
current limit at 500mA until PD_RDY is received.

BUG=b:30744563,chrome-os-partner:59311,chrome-os-partner:44340
BRANCH=ryu, gru, glados
TEST=Manual on kevin, set ilim to 5V through `chglim` console command,
attach zinger. Set ilim to 20V through `chglim`, verify that ilim goes
from 3A to 500mA to 3A.

Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
Change-Id: I452f183cfb958780e336a9f99dc6398356de17a0
Reviewed-on: https://chromium-review.googlesource.com/399918
Commit-Ready: Shawn N <shawnn@chromium.org>
Tested-by: Shawn N <shawnn@chromium.org>
Reviewed-by: Todd Broch <tbroch@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/include/charge_manager.h b/include/charge_manager.h
index 939471163b..71cc8589aa 100644
--- a/include/charge_manager.h
+++ b/include/charge_manager.h
@@ -73,6 +73,16 @@ enum ceil_requestor {
 /* Update charge ceiling for a given port / requestor */
 void charge_manager_set_ceil(int port, enum ceil_requestor requestor, int ceil);
 
+/*
+ * Update PD charge ceiling for a given port. In the event that our ceiling
+ * is currently above ceil, change the current limit before returning, without
+ * waiting for a charge manager refresh. This function should only be used in
+ * time-critical situations where we absolutely cannot proceed without limiting
+ * our input current, and it should only be called from the PD tasks.
+ * If you ever call this function then you are a terrible person.
+ */
+void charge_manager_force_ceil(int port, int ceil);
+
 /* Select an 'override port', which is always the preferred charge port */
 int charge_manager_set_override(int port);
 int charge_manager_get_override(void);