usb_pd: Add host command to limit external charger voltage / current

PD charger voltage + current can now be limited with
EC_CMD_EXTERNAL_POWER_LIMIT. The limit is automatically cleared when the
AP transitions out of S0 into S3 / suspend.

BUG=chrome-os-partner:43285
TEST=Manual on Samus w/ zinger.
- Plug zinger, verify charging at 20V/3A.
- `ectool extpwrlimit 3000 12000 --dev=1`, verify charging at 12V/3A
- `ectool extpwrlimit 1000 5000 --dev=1`, verify charging at 5V/1A
- Plug zinger into other port, verify still charging at 5V/1A
- `powerd_dbus_suspend`, verify charging at 20V/3A
- `chglim 2000 12000`, verify charging at 12V/2A
- `ectool extpwrlimit 0xffff 0xffff --dev=1`, verify charging at 20V/3A
- `chglim 1000 20000`, verify charging at 20V/1A
- `chglim`, verify charging at 20V/3A
BRANCH=ryu

Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
Change-Id: I6cd5377be91b3df75f99cb414fd3fa5a463b56cb
Reviewed-on: https://chromium-review.googlesource.com/293954
Reviewed-by: Todd Broch <tbroch@chromium.org>
Reviewed-by: Alec Berg <alecaberg@chromium.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/include/usb_pd.h b/include/usb_pd.h
index 5b42b687e0..6ca88bb55a 100644
--- a/include/usb_pd.h
+++ b/include/usb_pd.h
@@ -947,6 +947,15 @@ int pd_set_power_supply_ready(int port);
 void pd_request_source_voltage(int port, int mv);
 
 /**
+ * Set a voltage limit from the PD source.
+ *
+ * If the source is currently active, it triggers a new negotiation.
+ * @param port USB-C port number
+ * @param mv limit voltage in millivolts.
+ */
+void pd_set_external_voltage_limit(int port, int mv);
+
+/**
  * Set the PD input current limit.
  *
  * @param port USB-C port number