usb_pd: request preferred voltage PDO

Add CONFIG_USB_PD_PREFER_MV to support PD will request preferred
voltage.
One should define pd_pref_config, including preferd voltage, e.g. 5000,
and PD_PREFER_BOOST or PD_PREFER_BUCK based on the board charging
efficiency. Also, system PLT power is needed for evaluating
board's desired power.

The option will try to find a most fit PDO:
 1. Pick the PDO which fulfills the system desired power. If a preferred
    voltage PDO doesn't provide enough power, it will be skipped.
 2. If none of the PDO meets the preferred voltage, it will pick the
    closest voltage PDO based on prefer boost or prefer bulk.
 3. The system desired power will be constantly updated when system in
    constant voltage stage (battery percent > 70%). This is done by
    monitoring the battery charging current.
 4. If the system desired power changes, it will re-evaluate the PDO and
    send request if has a better fit.

TEST=Set prefer_mv to 5000 and ensure PD voltage could pick 9V/12V when
     desired voltage > 15W (5V/3A) and pick 5V when
     desired voltage <= 15W
BUG=b:141170279 b:141903096 b:144073892
BRANCH=kukui

Change-Id: I94646cb1c74c10cf8db889f19c3df6339844042c
Signed-off-by: Yilun Lin <yllin@chromium.org>
Signed-off-by: Eric Yilun Lin <yllin@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1871499

1 files changed, 7 insertions, 0 deletions

diff --git a/include/charge_manager.h b/include/charge_manager.h
index 2a3ca27d74..b68bf34801 100644
--- a/include/charge_manager.h
+++ b/include/charge_manager.h
@@ -206,6 +206,13 @@ int charge_manager_get_charger_current(void);
  */
 int charge_manager_get_charger_voltage(void);
 
+/**
+ * Get the charger supplier.
+ *
+ * @return	enum charge_supplier
+ */
+enum charge_supplier charge_manager_get_supplier(void);
+
 #ifdef CONFIG_USB_PD_LOGGING
 /* Save power state log entry for the given port */
 void charge_manager_save_log(int port);