Battery: Compensate remaining charge to match full capacity

If remaining charge is more than x% of the full capacity, the
remaining charge is raised to the full capacity before it's
reported to the rest of the system.

Some batteries don't update full capacity timely or don't update it
at all. On such systems, compensation is required to guarantee
the remaining charge will be equal to the full capacity eventually.

On some systems, Rohm charger generates audio noise when the battery
is fully charged and AC is plugged. A workaround is to do charge-
discharge cycles between 93 and 100%. On such systems, compensation
was also applied to mask this cycle from users.

This used to be done in ACPI, thus, all software components except EC
was able to see the compensated charge. This patch is moving the logic
to EC. With this and the following changes, EC can see what the rest
of the system sees, thus, can control LEDs synchronously (to the
display percentage).

Another rationale of this move is EC can perform more granular and
precise compensation than ACPI since it has more knowledge about the
battery and the charger.

Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>

CQ-DEPEND=CL:1320195
BUG=b:109954565,b:80270446
BRANCH=none
TEST=Verify charge LED changes to white (full) on Sona synchronously
to the display percentage.
TEST=Verify charge LED changes to blinking white (low) on Sona
within 30 seconds synchronously to the display percentage.

Change-Id: I4e3f70efa39e62c91cb8894b603c551cd23511aa
Reviewed-on: https://chromium-review.googlesource.com/1312204
Commit-Ready: Daisuke Nojiri <dnojiri@chromium.org>
Tested-by: Daisuke Nojiri <dnojiri@chromium.org>
Reviewed-by: Daisuke Nojiri <dnojiri@chromium.org>

1 files changed, 24 insertions, 0 deletions

diff --git a/include/battery.h b/include/battery.h
index 96eb1ea705..38d7dd32aa 100644
--- a/include/battery.h
+++ b/include/battery.h
@@ -403,4 +403,28 @@ void battery_memmap_set_index(enum battery_index index);
 extern struct i2c_stress_test_dev battery_i2c_stress_test_dev;
 #endif
 
+/*
+ * If remaining charge is more than x% of the full capacity, the
+ * remaining charge is raised to the full capacity before it's
+ * reported to the rest of the system.
+ *
+ * Some batteries don't update full capacity timely or don't update it
+ * at all. On such systems, compensation is required to guarantee
+ * the remaining charge will be equal to the full capacity eventually.
+ *
+ * On some systems, Rohm charger generates audio noise when the battery
+ * is fully charged and AC is plugged. A workaround is to do charge-
+ * discharge cycles between 93 and 100%. On such systems, compensation
+ * was also applied to mask this cycle from users.
+ *
+ * This used to be done in ACPI, thus, all software components except EC
+ * was seeing the compensated charge. Now we do it in EC. It has more
+ * knowledge on the charger and the battery. So, it can perform more
+ * granular and precise compensation.
+ *
+ * TODO: Currently, this is applied only to smart battery. Apply it to other
+ *       battery drivers as needed.
+ */
+void battery_compensate_params(struct batt_params *batt);
+
 #endif /* __CROS_EC_BATTERY_H */