charger_manager: update charge profile upon temperature zone change

Battery vendors like UER suggest to program Low Charge Voltage in case of high or low temperatures. So a battery can have different charge profile with in the battery operating temperature limits.

Next, there could be events like drop or rise in VBUS voltage in that case we might have to adjust the charge current to stabilize VBUS voltage.

This patch allows the Charger-Manager to adjust the charging parameters upon events like VBUS rise or drop and allows batteries to have multiple charge profiles for different temperature zones.

Signed-off-by Ramakrishna Pallala <[email protected]>

---
 Documentation/power/charger-manager.txt |   10 ++++++++++
 drivers/power/charger-manager.c         |    6 +++++-
 include/linux/power/charger-manager.h   |    5 +++++
 3 files changed, 20 insertions(+), 1 deletions(-)

Documentation/power/charger-manager.txt +10 -0

index b4f7f4b..6fa2a10 100644
@@ -50,6 +50,15 @@ Charger Manager supports the following:
 	restarts charging. This check is also performed while suspended by
 	setting wakeup time accordingly and using suspend_again.
 
+* Support for adjusting charging parameters
+	Batteries can have different charge profiles with in the battery
+	operating temperature limits. And events like drop or rise in VBUS
+	voltage require adjustment of charge current to stabilize VBUS voltage.
+
+	Charger Manager provides a function pointer "charging_zone_changed" which
+	can be implemented by platform/core drivers and Charger Manager checks
+	this function to update the charger.
+
 * Support for uevent-notify
 	With the charger-related events, the device sends
 	notification to users with UEVENT.

@@ -169,6 +178,7 @@ char *psy_fuel_gauge;
 	: Power-supply-class name of the fuel gauge.
 
 int (*temperature_out_of_range)(int *mC);
+bool (*charging_zone_changed)(int mC);
 bool measure_battery_temp;
 	: This callback returns 0 if the temperature is safe for charging,
 	a positive number if it is too hot to charge, and a negative number

drivers/power/charger-manager.c +5 -1

index 86935ec..9f46353 100644
@@ -424,13 +424,17 @@ static void fullbatt_vchk(struct work_struct *work)
 static bool _cm_monitor(struct charger_manager *cm)
 {
 	struct charger_desc *desc = cm->desc;
+	bool update_charger = false;
 	int temp = desc->temperature_out_of_range(&cm->last_temp_mC);
 
 	dev_dbg(cm->dev, "monitoring (%2.2d.%3.3dC)\n",
 		cm->last_temp_mC / 1000, cm->last_temp_mC % 1000);
 
+	if (desc->charging_zone_changed)
+		update_charger = desc->charging_zone_changed(cm->last_temp_mC);
+
 	/* It has been stopped or charging already */
-	if (!!temp == !!cm->emergency_stop)
+	if ((!!temp == !!cm->emergency_stop) && !update_charger)
 		return false;
 
 	if (temp) {

include/linux/power/charger-manager.h +5 -0

index 241065c..302107d 100644
@@ -90,6 +90,10 @@ struct charger_global_desc {
  *	return_value > 0: overheat
  *	return_value == 0: normal
  *	return_value < 0: cold
+ * @charging_zone_changed:
+ *	Determine whether charge profile need an update
+ *	return_value true if charge profile update required
+ *	return_value false if charge profile update is not required
  * @measure_battery_temp:
  *	true: measure battery temperature
  *	false: measure ambient temperature

@@ -114,6 +118,7 @@ struct charger_desc {
 	char *psy_fuel_gauge;
 
 	int (*temperature_out_of_range)(int *mC);
+	bool (*charging_zone_changed)(int mC);
 	bool measure_battery_temp;
 };
 

Signature · 1 line

1.7.0.4

Quoted 5 lines

This patch allows the Charger-Manager to adjust the charging parameters upon events like VBUS rise or drop and allows batteries to have multiple charge profiles for different temperature zones.

Signed-off-by Ramakrishna Pallala <[email protected]>

I don't see how the parameters are changed when update_charger is true.

Are you intending to do it at userspace after getting uevent_notify()? (I don't think it's good)

If the intension is to update some of the charger-manager internal parameters (struct charger_manager's struct charger_desc) according to the temperature, we'd need a more general method that can also update values in the charger-manager context.

For example, instead of simply putting a callback to determine whether an update is required or not, a table of (including hysterisis) temperatures and values to be updated (or callbacks to update charger_desc based on the temperature) might be a starting point. You may also need to consider using notifier chain w/ temperatures.

Quoted 8 lines

Quoted 6 lines

This patch allows the Charger-Manager to adjust the charging parameters upon events like VBUS rise or drop and allows batteries to have multiple charge profiles for different temperature zones.

Signed-off-by Ramakrishna Pallala <[email protected]>

I don't see how the parameters are changed when update_charger is true.

My initial thought was to keep these details hide from CM.

Quoted 2 lines

Are you intending to do it at userspace after getting uevent_notify()? (I don't think it's good)

No, we will do it from driver only.

Quoted 3 lines

If the intension is to update some of the charger-manager internal parameters (struct charger_manager's struct charger_desc) according to the temperature, we'd need a more general method that can also update

values in the charger-manager context.

Quoted 5 lines

For example, instead of simply putting a callback to determine whether an update is required or not, a table of (including hysterisis) temperatures and values to be updated (or callbacks to update charger_desc based on the temperature) might be a starting point. You

may also need to consider using notifier chain w/ temperatures.

Quoted 1 line

Yes I agree, I will submit another patch with these changes.

As part of charge enablement we generally program charge current, charge voltage into the charger chip.

We can pass the charging parameters CC and CV in two ways.
1. Add these params in charger_desc struct and the charger regulator can get these params using container_of() call? but becomes complex.

2. use regulator_set_voltage()/regulator_set_current_limit() functions to set the CV and CC params.
but not suitable as is, we have add support in regulator framework

3. use regulator_get_drvdata()/regulator_set_drvdata() to set CC & CV params. These functions allow us to add more params in future if required.

I am thinking of using option 3.

Let me know your feedback.

Thanks,
Ram

N떑꿩?툤y鉉싕b쾊Ф푤v??頻{.n?돴쪐{콗喩zX㎍썳變
}찠꼿쟺?j:+v돣?쳭喩zZ+€?zf＂톒쉱?넮녬i鎬z?췿ⅱ?솳鈺??刪
f뷌^j푹y쬶끷@A첺뛴

0띠h??i

Quoted 8 lines

As part of charge enablement we generally program charge current, charge voltage into the charger chip.

We can pass the charging parameters CC and CV in two ways.
1. Add these params in charger_desc struct and the charger regulator can get these params using container_of() call? but becomes complex.

Quoted 4 lines

2. use regulator_set_voltage()/regulator_set_current_limit() functions to set the CV and CC params.
but not suitable as is, we have add support in regulator framework

regulator_ops has support for set_current_limit and set_voltage. Can we use the same for setting CC and CV?