Message-Id: <201203010058.02772.rjw@sisk.pl>
Date:	Thu, 1 Mar 2012 00:58:02 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Donggeun Kim <dg77.kim@...sung.com>
Cc:	linux-kernel@...r.kernel.org, cbouatmailru@...il.com,
	len.brown@...el.com, pavel@....cz, rdunlap@...otime.net,
	myungjoo.ham@...sung.com, kyungmin.park@...sung.com
Subject: Re: [PATCH 1/2] power_supply: Charger-Manager: poll battery health in normal state

On Thursday, February 23, 2012, Donggeun Kim wrote:
> Charger-Manager needs to check battery health in normal state
> as well as suspend-to-RAM state.
> When the battery is fully charged,
> Charger-Manager needs to determine when the chargers restart charging.
> 
> This patch allows Charger-Manager to monitor battery health in normal state
> and handle operation for chargers after battery is fully charged.
> 
> Signed-off-by: MyungJoo Ham <myungjoo.ham@...sung.com>
> Signed-off-by: Donggeun Kim <dg77.kim@...sung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@...sung.com>
> ---
>  Documentation/power/charger-manager.txt |   25 ++++-
>  drivers/power/charger-manager.c         |  230 +++++++++++++++++++++++++++++++
>  include/linux/power/charger-manager.h   |   25 ++++
>  3 files changed, 279 insertions(+), 1 deletions(-)
> 
> diff --git a/Documentation/power/charger-manager.txt b/Documentation/power/charger-manager.txt
> index fdcca99..47f7fdc 100644
> --- a/Documentation/power/charger-manager.txt
> +++ b/Documentation/power/charger-manager.txt
> @@ -44,6 +44,12 @@ Charger Manager supports the following:
>  	Normally, the platform will need to resume and suspend some devices
>  	that are used by Charger Manager.
>  
> +* Support for premature full-battery event handling
> +	If the battery voltage drops by "fullbatt_vchkdrop_uV" after
> +	"fullbatt_vchkdrop_ms" from the full-battery event, the framework
> +	restarts charging. This check is also performed while suspended by
> +	setting wakeup time accordingly and using suspend_again.
> +
>  2. Global Charger-Manager Data related with suspend_again
>  ========================================================
>  In order to setup Charger Manager with suspend-again feature
> @@ -55,7 +61,7 @@ if there are multiple batteries. If there are multiple batteries, the
>  multiple instances of Charger Manager share the same charger_global_desc
>  and it will manage in-suspend monitoring for all instances of Charger Manager.
>  
> -The user needs to provide all the two entries properly in order to activate
> +The user needs to provide all the three entries properly in order to activate
>  in-suspend monitoring:
>  
>  struct charger_global_desc {
> @@ -74,6 +80,11 @@ bool (*rtc_only_wakeup)(void);
>  	same struct. If there is any other wakeup source triggered the
>  	wakeup, it should return false. If the "rtc" is the only wakeup
>  	reason, it should return true.
> +
> +bool assume_timer_stops_in_suspend;
> +	: if true, Charger Manager assumes that
> +	the timer (CM uses jiffies as timer) stops during suspend. Then, CM
> +	assumes that the suspend-duration is same as the alarm length.

The description here is not 100% clear to me.  Is it supposed to mean
that if assume_timer_stops_in_suspend is set, the charger manager will assume
that there won't be timer events while suspended?

>  };
>  
>  3. How to setup suspend_again
> @@ -111,6 +122,16 @@ enum polling_modes polling_mode;
>  	  CM_POLL_CHARGING_ONLY: poll this battery if and only if the
>  				 battery is being charged.
>  
> +unsigned int fullbatt_vchkdrop_ms;
> +unsigned int fullbatt_vchkdrop_uV;
> +	: If both have non-zero values, Charger Manager will check the
> +	battery voltage drop fullbatt_vchkdrop_ms after the battery is fully
> +	charged. If the voltage drop is over fullbatt_vchkdrop_uV, Charger
> +	Manager will try to recharge the battery by disabling and enabling
> +	chargers. Recharge with voltage drop condition only (without delay
> +	condition) is needed to be implemented with hardware interrupts from
> +	fuel gauges or charger devices/chips.
> +
>  unsigned int fullbatt_uV;
>  	: If specified with a non-zero value, Charger Manager assumes
>  	that the battery is full (capacity = 100) if the battery is not being
> @@ -122,6 +143,8 @@ unsigned int polling_interval_ms;
>  	this battery every polling_interval_ms or more frequently.
>  
>  enum data_source battery_present;
> +	: CM_ASSUME_ALWAYS_TRUE: assume that the battery exists.

I'd call that CM_BATTERY_PRESENT

> +	CM_ASSUME_ALWAYS_FALSE: assume that the battery does not exists.

And that CM_NO_BATTERY

>  	CM_FUEL_GAUGE: get battery presence information from fuel gauge.
>  	CM_CHARGER_STAT: get battery presence from chargers.
>  
> diff --git a/drivers/power/charger-manager.c b/drivers/power/charger-manager.c
> index 88fd971..9ecde4c 100644
> --- a/drivers/power/charger-manager.c
> +++ b/drivers/power/charger-manager.c
> @@ -57,6 +57,12 @@ static bool cm_suspended;
>  static bool cm_rtc_set;
>  static unsigned long cm_suspend_duration_ms;
>  
> +/* About normal (not suspended) monitoring */
> +static unsigned long polling_jiffy = ULONG_MAX; /* ULONG_MAX: no polling */
> +static unsigned long next_polling; /* Next appointed polling time */
> +static struct workqueue_struct *cm_wq; /* init at driver add */
> +static struct delayed_work cm_monitor_work; /* init at driver add */
> +
>  /* Global charger-manager description */
>  static struct charger_global_desc *g_desc; /* init with setup_charger_manager */
>  
> @@ -71,6 +77,12 @@ static bool is_batt_present(struct charger_manager *cm)
>  	int i, ret;
>  
>  	switch (cm->desc->battery_present) {
> +	case CM_ASSUME_ALWAYS_TRUE:
> +		present = true;
> +		break;
> +	case CM_ASSUME_ALWAYS_FALSE:
> +		present = false;

You don't have to do preset = false here, because it's false already.

> +		break;
>  	case CM_FUEL_GAUGE:
>  		ret = cm->fuel_gauge->get_property(cm->fuel_gauge,
>  				POWER_SUPPLY_PROP_PRESENT, &val);
> @@ -282,6 +294,26 @@ static int try_charger_enable(struct charger_manager *cm, bool enable)
>  }
>  
>  /**
> + * try_charger_restart - Restart charging.
> + * @cm: the Charger Manager representing the battery.
> + *
> + * Restart charging by turning off and on the charger.
> + */
> +static int try_charger_restart(struct charger_manager *cm)
> +{
> +	int err;
> +
> +	if (cm->emergency_stop)
> +		return -EAGAIN;
> +
> +	err = try_charger_enable(cm, false);
> +	if (err)
> +		return err;
> +
> +	return try_charger_enable(cm, true);
> +}
> +
> +/**
>   * uevent_notify - Let users know something has changed.
>   * @cm: the Charger Manager representing the battery.
>   * @event: the event string.
> @@ -339,6 +371,47 @@ static void uevent_notify(struct charger_manager *cm, const char *event)
>  }
>  
>  /**
> + * fullbatt_vchk - Check voltage drop some times after "FULL" event.
> + * @work: the work_struct appointing the function
> + *
> + * If a user has designated "fullbatt_vchkdrop_ms/uV" values with
> + * charger_desc, Charger Manager checks voltage drop after the battery
> + * "FULL" event. It checks whether the voltage has dropped more than
> + * fullbatt_vchkdrop_uV by calling this function after fullbatt_vchkrop_ms.
> + */
> +static void fullbatt_vchk(struct work_struct *work)
> +{
> +	struct delayed_work *dwork =
> +		container_of(work, struct delayed_work, work);

There's the to_delayed_work() function for that.

> +	struct charger_manager *cm = container_of(dwork,
> +			struct charger_manager, fullbatt_vchk_work);
> +	struct charger_desc *desc = cm->desc;
> +	int batt_uV, err, diff;
> +
> +	/* remove the appointment for fullbatt_vchk */
> +	cm->fullbatt_vchk_jiffies_at = 0;
> +
> +	if (!desc->fullbatt_vchkdrop_uV || !desc->fullbatt_vchkdrop_ms)
> +		return;
> +
> +	err = get_batt_uV(cm, &batt_uV);
> +	if (err) {
> +		dev_err(cm->dev, "%s: get_batt_uV error(%d).\n", __func__, err);
> +		return;
> +	}
> +
> +	diff = cm->fullbatt_vchk_uV;
> +	diff -= batt_uV;
> +
> +	dev_dbg(cm->dev, "VBATT dropped %duV after full-batt.\n", diff);
> +
> +	if (diff > desc->fullbatt_vchkdrop_uV) {
> +		try_charger_restart(cm);
> +		uevent_notify(cm, "Recharge");
> +	}
> +}
> +
> +/**
>   * _cm_monitor - Monitor the temperature and return true for exceptions.
>   * @cm: the Charger Manager representing the battery.
>   *
> @@ -395,6 +468,68 @@ static bool cm_monitor(void)
>  	return stop;
>  }
>  
> +/**
> + * _setup_polling - Setup the next instance of polling.
> + * @work: work_struct of the function _setup_polling.
> + */
> +static void _setup_polling(struct work_struct *work)
> +{
> +	unsigned long min = ULONG_MAX;
> +	struct charger_manager *cm;
> +	bool keep_polling = false;
> +	unsigned long _next_polling;
> +
> +	mutex_lock(&cm_list_mtx);
> +
> +	list_for_each_entry(cm, &cm_list, entry) {
> +		if (is_polling_required(cm) && cm->desc->polling_interval_ms) {
> +			keep_polling = true;
> +
> +			if (min > cm->desc->polling_interval_ms)
> +				min = cm->desc->polling_interval_ms;
> +		}
> +	}
> +
> +	polling_jiffy = msecs_to_jiffies(min);
> +	if (polling_jiffy <= CM_JIFFIES_SMALL)
> +		polling_jiffy = CM_JIFFIES_SMALL + 1;
> +
> +	if (!keep_polling)
> +		polling_jiffy = ULONG_MAX;
> +	if (polling_jiffy == ULONG_MAX)
> +		goto out;
> +
> +	WARN(cm_wq == NULL, "charger-manager: workqueue not initialized"
> +			    ". try it later. %s\n", __func__);
> +
> +	_next_polling = jiffies + polling_jiffy;
> +
> +	if (!delayed_work_pending(&cm_monitor_work) ||
> +	    (delayed_work_pending(&cm_monitor_work) &&
> +	     time_after(next_polling, _next_polling))) {
> +		cancel_delayed_work(&cm_monitor_work);

Shouldn't that be cancel_delayes_work_sync() ?

> +		next_polling = jiffies + polling_jiffy;
> +		queue_delayed_work(cm_wq, &cm_monitor_work, polling_jiffy);
> +	}
> +
> +out:
> +	mutex_unlock(&cm_list_mtx);
> +}
> +static DECLARE_WORK(setup_polling, _setup_polling);
> +
> +/**
> + * cm_monitor_poller - The Monitor / Poller.
> + * @work: work_struct of the function cm_monitor_poller
> + *
> + * During non-suspended state, cm_monitor_poller is used to poll and monitor
> + * the batteries.
> + */
> +static void cm_monitor_poller(struct work_struct *work)
> +{
> +	cm_monitor();
> +	schedule_work(&setup_polling);
> +}
> +
>  static int charger_get_property(struct power_supply *psy,
>  		enum power_supply_property psp,
>  		union power_supply_propval *val)
> @@ -616,6 +751,20 @@ static bool cm_setup_timer(void)
>  	mutex_lock(&cm_list_mtx);
>  
>  	list_for_each_entry(cm, &cm_list, entry) {
> +		unsigned int fbchk_ms = 0;
> +
> +		/* fullbatt_vchk is required. setup timer for that */
> +		if (cm->fullbatt_vchk_jiffies_at) {
> +			fbchk_ms = jiffies_to_msecs(cm->fullbatt_vchk_jiffies_at
> +						    - jiffies);
> +			if (cm->fullbatt_vchk_jiffies_at <= jiffies

time_before_eq_jiffies() ?

> ||
> +				msecs_to_jiffies(fbchk_ms) < CM_JIFFIES_SMALL) {
> +				fullbatt_vchk(&cm->fullbatt_vchk_work.work);
> +				fbchk_ms = 0;
> +			}
> +		}
> +		CM_MIN_VALID(wakeup_ms, fbchk_ms);
> +
>  		/* Skip if polling is not required for this CM */
>  		if (!is_polling_required(cm) && !cm->emergency_stop)
>  			continue;
> @@ -675,6 +824,27 @@ static bool cm_setup_timer(void)
>  	return false;
>  }
>  
> +static bool _cm_fbchk_in_suspend(struct charger_manager *cm)

Why do you need it to return bool?

> +{
> +	unsigned long jiffy_now = jiffies;
> +
> +	if (!cm->fullbatt_vchk_jiffies_at)
> +		return false;
> +
> +	if (g_desc && g_desc->assume_timer_stops_in_suspend)
> +		jiffy_now += msecs_to_jiffies(cm_suspend_duration_ms);
> +
> +	/* Execute now if it's going to be executed not too long after */
> +	jiffy_now += CM_JIFFIES_SMALL;
> +
> +	if (time_after_eq(jiffy_now, cm->fullbatt_vchk_jiffies_at)) {
> +		fullbatt_vchk(&cm->fullbatt_vchk_work.work);
> +		return true;
> +	}
> +
> +	return false;
> +}
> +
>  /**
>   * cm_suspend_again - Determine whether suspend again or not
>   *
> @@ -696,6 +866,8 @@ bool cm_suspend_again(void)
>  	ret = true;
>  	mutex_lock(&cm_list_mtx);
>  	list_for_each_entry(cm, &cm_list, entry) {
> +		_cm_fbchk_in_suspend(cm);
> +
>  		if (cm->status_save_ext_pwr_inserted != is_ext_pwr_online(cm) ||
>  		    cm->status_save_batt != is_batt_present(cm))
>  			ret = false;
> @@ -797,6 +969,21 @@ static int charger_manager_probe(struct platform_device *pdev)
>  	memcpy(cm->desc, desc, sizeof(struct charger_desc));
>  	cm->last_temp_mC = INT_MIN; /* denotes "unmeasured, yet" */
>  
> +	/*
> +	 * The following two do not need to be errors.
> +	 * Users may intentionally ignore those two features.
> +	 */
> +	if (desc->fullbatt_uV == 0) {
> +		dev_info(&pdev->dev, "Ignoring full-battery voltage threshold"
> +					" as it is not supplied.");
> +	}
> +	if (!desc->fullbatt_vchkdrop_ms || !desc->fullbatt_vchkdrop_uV) {
> +		dev_info(&pdev->dev, "Disabling full-battery voltage drop "
> +				"checking mechanism as it is not supplied.");
> +		desc->fullbatt_vchkdrop_ms = 0;
> +		desc->fullbatt_vchkdrop_uV = 0;
> +	}
> +
>  	if (!desc->charger_regulators || desc->num_charger_regulators < 1) {
>  		ret = -EINVAL;
>  		dev_err(&pdev->dev, "charger_regulators undefined.\n");
> @@ -905,6 +1092,8 @@ static int charger_manager_probe(struct platform_device *pdev)
>  		cm->charger_psy.num_properties++;
>  	}
>  
> +	INIT_DELAYED_WORK(&cm->fullbatt_vchk_work, fullbatt_vchk);
> +
>  	ret = power_supply_register(NULL, &cm->charger_psy);
>  	if (ret) {
>  		dev_err(&pdev->dev, "Cannot register charger-manager with"
> @@ -930,6 +1119,8 @@ static int charger_manager_probe(struct platform_device *pdev)
>  	list_add(&cm->entry, &cm_list);
>  	mutex_unlock(&cm_list_mtx);
>  
> +	schedule_work(&setup_polling);
> +
>  	return 0;
>  
>  err_chg_enable:
> @@ -961,10 +1152,14 @@ static int __devexit charger_manager_remove(struct platform_device *pdev)
>  	list_del(&cm->entry);
>  	mutex_unlock(&cm_list_mtx);
>  
> +	schedule_work(&setup_polling);
> +
>  	if (desc->charger_regulators)
>  		regulator_bulk_free(desc->num_charger_regulators,
>  					desc->charger_regulators);
>  
> +	try_charger_enable(cm, false);
> +
>  	power_supply_unregister(&cm->charger_psy);
>  	kfree(cm->charger_psy.properties);
>  	kfree(cm->charger_stat);
> @@ -1007,6 +1202,7 @@ static int cm_suspend_prepare(struct device *dev)
>  		cm_suspended = true;
>  	}
>  
> +	cancel_delayed_work(&cm->fullbatt_vchk_work);

Why do you need to cancel it here?

>  	cm->status_save_ext_pwr_inserted = is_ext_pwr_online(cm);
>  	cm->status_save_batt = is_batt_present(cm);
>  
> @@ -1036,6 +1232,34 @@ static void cm_suspend_complete(struct device *dev)
>  		cm_rtc_set = false;
>  	}
>  
> +	/* Re-enqueue delayed work (fullbatt_vchk_work) */
> +	if (cm->fullbatt_vchk_jiffies_at) {
> +		unsigned long delay = 0;
> +		unsigned long now = jiffies;

I'd do

+		unsigned long now = jiffies + CM_JIFFIES_SMALL;

which would simplify the code below.

> +
> +		if (time_after_eq(now + CM_JIFFIES_SMALL,
> +				  cm->fullbatt_vchk_jiffies_at)) {
> +			delay = (unsigned long)((long)(now + CM_JIFFIES_SMALL)
> +				- (long)(cm->fullbatt_vchk_jiffies_at));

I don't really think that handles the possible overflow correctly (if you get
a negative result and then covert it to unsigned long, that still will produce a
big positive number).

> +			delay = jiffies_to_msecs(delay);
> +		} else {
> +			delay = 0;
> +		}
> +
> +		/*
> +		 * Account for cm_suspend_duration_ms if
> +		 * assume_timer_stops_in_suspend is active
> +		 */
> +		if (g_desc && g_desc->assume_timer_stops_in_suspend) {
> +			if (delay > cm_suspend_duration_ms)
> +				delay -= cm_suspend_duration_ms;
> +			else
> +				delay = 0;
> +		}
> +
> +		queue_delayed_work(cm_wq, &cm->fullbatt_vchk_work,
> +				   msecs_to_jiffies(delay));
> +	}
>  	uevent_notify(cm, NULL);
>  }
>  
> @@ -1057,12 +1281,18 @@ static struct platform_driver charger_manager_driver = {
>  
>  static int __init charger_manager_init(void)
>  {
> +	cm_wq = create_freezable_workqueue("charger_manager");
> +	INIT_DELAYED_WORK(&cm_monitor_work, cm_monitor_poller);
> +
>  	return platform_driver_register(&charger_manager_driver);
>  }
>  late_initcall(charger_manager_init);
>  
>  static void __exit charger_manager_cleanup(void)
>  {
> +	destroy_workqueue(cm_wq);
> +	cm_wq = NULL;
> +
>  	platform_driver_unregister(&charger_manager_driver);
>  }
>  module_exit(charger_manager_cleanup);
> diff --git a/include/linux/power/charger-manager.h b/include/linux/power/charger-manager.h
> index 4f75e53..78b9865 100644
> --- a/include/linux/power/charger-manager.h
> +++ b/include/linux/power/charger-manager.h
> @@ -18,6 +18,8 @@
>  #include <linux/power_supply.h>
>  
>  enum data_source {
> +	CM_ASSUME_ALWAYS_TRUE,
> +	CM_ASSUME_ALWAYS_FALSE,
>  	CM_FUEL_GAUGE,
>  	CM_CHARGER_STAT,
>  };
> @@ -38,11 +40,18 @@ enum polling_modes {
>   *	rtc_only_wakeup() returning false.
>   *	If the RTC given to CM is the only wakeup reason,
>   *	rtc_only_wakeup should return true.
> + * @assume_timer_stops_in_suspend:
> + *	Assume that the jiffy timer stops in suspend-to-RAM.
> + *	When enabled, CM does not rely on jiffies value in
> + *	suspend_again and assumes that jiffies value does not
> + *	change during suspend.
>   */
>  struct charger_global_desc {
>  	char *rtc_name;
>  
>  	bool (*rtc_only_wakeup)(void);
> +
> +	bool assume_timer_stops_in_suspend;
>  };
>  
>  /**
> @@ -50,6 +59,11 @@ struct charger_global_desc {
>   * @psy_name: the name of power-supply-class for charger manager
>   * @polling_mode:
>   *	Determine which polling mode will be used
> + * @fullbatt_vchkdrop_ms:
> + * @fullbatt_vchkdrop_uV:
> + *	Check voltage drop after the battery is fully charged.
> + *	If it has dropped more than fullbatt_vchkdrop_uV after
> + *	fullbatt_vchkdrop_ms, CM will restart charging.
>   * @fullbatt_uV: voltage in microvolt
>   *	If it is not being charged and VBATT >= fullbatt_uV,
>   *	it is assumed to be full.
> @@ -76,6 +90,8 @@ struct charger_desc {
>  	enum polling_modes polling_mode;
>  	unsigned int polling_interval_ms;
>  
> +	unsigned int fullbatt_vchkdrop_ms;
> +	unsigned int fullbatt_vchkdrop_uV;
>  	unsigned int fullbatt_uV;
>  
>  	enum data_source battery_present;
> @@ -101,6 +117,11 @@ struct charger_desc {
>   * @fuel_gauge: power_supply for fuel gauge
>   * @charger_stat: array of power_supply for chargers
>   * @charger_enabled: the state of charger
> + * @fullbatt_vchk_jiffies_at:
> + *	jiffies at the time full battery check will occur.
> + * @fullbatt_vchk_uV: voltage in microvolt
> + *	criteria for full battery
> + * @fullbatt_vchk_work: work queue for full battery check
>   * @emergency_stop:
>   *	When setting true, stop charging
>   * @last_temp_mC: the measured temperature in milli-Celsius
> @@ -121,6 +142,10 @@ struct charger_manager {
>  
>  	bool charger_enabled;
>  
> +	unsigned long fullbatt_vchk_jiffies_at;
> +	unsigned int fullbatt_vchk_uV;
> +	struct delayed_work fullbatt_vchk_work;
> +
>  	int emergency_stop;
>  	int last_temp_mC;
>  
> 

Thanks,
Rafael
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