Message-Id: <201112262127.30271.rjw@sisk.pl>
Date:	Mon, 26 Dec 2011 21:27:30 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Donggeun Kim <dg77.kim@...sung.com>
Cc:	linux-pm@...r.kernel.org, len.brown@...el.com, pavel@....cz,
	rdunlap@...otime.net, cbouatmailru@...il.com, pali.rohar@...il.com,
	prakity@...vell.com, broonie@...nsource.wolfsonmicro.com,
	lars@...afoo.de, kyungmin.park@...sung.com,
	myungjoo.ham@...sung.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] power: Charger-Manager: add initial Charger-Manager driver

On Wednesday, December 21, 2011, Donggeun Kim wrote:
> Because battery health monitoring should be done even when suspended,
> it needs to wake up and suspend periodically. Thus, userspace battery
> monitoring may incur too much overhead; every device and task is woken
> up periodically. Charger Manager uses suspend-again to provide
> in-suspend monitoring.
> 
> This patch allows to monitor battery health in-suspend state.
> 
> Signed-off-by: Donggeun Kim <dg77.kim@...sung.com>
> Signed-off-by: MyungJoo Ham <myungjoo.ham@...sung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@...sung.com>
> ---
>  Documentation/power/charger-manager.txt |  150 ++++++
>  drivers/power/Kconfig                   |    9 +
>  drivers/power/Makefile                  |    1 +
>  drivers/power/charger-manager.c         |  771 +++++++++++++++++++++++++++++++
>  include/linux/power/charger-manager.h   |  131 ++++++
>  5 files changed, 1062 insertions(+), 0 deletions(-)
>  create mode 100644 Documentation/power/charger-manager.txt
>  create mode 100644 drivers/power/charger-manager.c
>  create mode 100644 include/linux/power/charger-manager.h
> 
> diff --git a/Documentation/power/charger-manager.txt b/Documentation/power/charger-manager.txt
> new file mode 100644
> index 0000000..99630e5
> --- /dev/null
> +++ b/Documentation/power/charger-manager.txt
> @@ -0,0 +1,150 @@
> +Charger Manager
> +	(C) 2011 MyungJoo Ham <myungjoo.ham@...sung.com>, GPL
> +
> +Charger Manager provides in-kernel battery charger management that
> +requires temperature monitoring during suspend-to-RAM state
> +and where each battery may have multiple chargers attached and the userland
> +wants to look at the aggregated information of the multiple chargers.
> +
> +Charger Manager is a platform_driver with power-supply-class entries.
> +An instance of Charger Manager (a platform-device created with Charger-Manager)
> +represents an independent battery with chargers. If there are multiple
> +batteries with their own chargers acting independently in a system,
> +the system may need multiple instances of Charger Manager.
> +
> +1. Introduction
> +===============
> +
> +Charger Manager supports the following:
> +
> +* Support for multiple chargers (e.g., a device with USB, AC, and solar panels)
> +	A system may have multiple chargers (or power sources) and some of
> +	they may be activated at the same time. Each charger may have its
> +	own power-supply-class and each power-supply-class can provide
> +	different information about the battery status. This framework
> +	aggregates charger-related information from multiple sources and
> +	shows combined information as a single power-supply-class.
> +
> +* Support for in suspend-to-RAM polling (with suspend_again callback)
> +	While the battery is being charged and the system is in suspend-to-RAM,
> +	we may need to monitor the battery health by looking at the ambient or
> +	battery temperature. We can accomplish this by waking up the system
> +	periodically. However, such a method wakes up devices unncessary for
> +	monitoring the battery health and tasks, and user processes that are
> +	supposed to be kept suspended. That, in turn, incurs unnecessary power
> +	consumption and slow down charging process. Or even, such peak power
> +	consumption can stop chargers in the middle of charging
> +	(external power input < device power consumption), which not
> +	only affects the charging time, but the lifespan of the battery.
> +
> +	Charger Manager provides a function "cm_suspend_again" that can be
> +	used as suspend_again callback of platform_suspend_ops. If the platform
> +	requires tasks other than cm_suspend_again, it may implement its own
> +	suspend_again callback that calls cm_suspend_again in the middle.
> +	Normally, the platform will need to resume and suspend some devices
> +	that are used by Charger Manager.
> +
> +2. Global Charger-Manager Data related with suspend_again
> +========================================================
> +In order to setup Charger Manager with suspend-again feature
> +(in-suspend monitoring), the user should provide charger_global_desc
> +with setup_charger_manager(struct charger_global_desc *).
> +This charger_global_desc data for in-suspend monitoring is global
> +as the name suggests. Thus, the user needs to provide only once even
> +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 three entries properly in order to activate
> +in-suspend monitoring:
> +

There seem to be only two entries in struct charger_global_desc below.

> +struct charger_global_desc {
> +
> +char *rtc;

That should be called rtc_name and I'm not sure if using the name here is
very convenient.  Perhaps it's better if the caller is responsible for
opening the RTC device.

> +	: The name of rtc (e.g., "rtc0") used to wakeup the system from
> +	suspend for Charger Manager. The alarm interrupt (AIE) of the rtc
> +	should be able to wake up the system from suspend. Charger Manager
> +	saves and restores the alarm value and use the previously-defined
> +	alarm if it is going to go off earlier than Charger Manager so that
> +	Charger Manager does not interfere with previously-defined alarms.
> +
> +bool (*is_rtc_only_wakeup_reason)(void);

I'd call that rtc_only_wakeup.

> +	: This callback should let CM know whether
> +	the wakeup-from-suspend is caused only by the alarm of "rtc" in the
> +	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.
> +};
> +
> +3. How to setup suspend_again
> +=============================
> +Charger Manager provides a function "extern bool cm_suspend_again(void)".
> +When cm_suspend_again is called, it monitors every battery. The suspend_ops
> +callback of the system's platform_suspend_ops can call cm_suspend_again
> +function to know whether Charger Manager wants to suspend again or not.
> +If there are no other devices or tasks that want to use suspend_again
> +feature, the platform_suspend_ops may directly refer to cm_suspend_again
> +for its suspend_again callback.
> +
> +The cm_suspend_again() returns true (meaning "I want to suspend again")
> +if the system was woken up by Charger Manager and the polling
> +(in-suspend monitoring) results in "normal".
> +
> +4. Charger-Manager Data (struct charger_desc)
> +=============================================
> +For each battery charged independently from other batteries (if a series of
> +batteries are charged by a single charger, they are counted as one independent
> +battery), an instance of Charger Manager is attached to it.
> +
> +struct charger_desc {
> +
> +enum polling_modes polling_mode;
> +	: CM_POLL_DISABLE: do not poll this battery.
> +	  CM_POLL_ALWAYS: always poll this battery.
> +	  CM_POLL_EXTERNAL_POWER_ONLY: poll this battery if and only if
> +				       an external power source is attached.
> +	  CM_POLL_CHARGING_ONLY: poll this battery if and only if the
> +				 battery is being charged.
> +
> +unsigned int polling_interval_ms;
> +	: Required polling interval in ms. Charger Manager will poll
> +	this battery every polling_interval_ms or more frequently.
> +
> +enum data_source battery_present;
> +	CM_FUEL_GAUGE: get battery presence information from fuel gauge.
> +	CM_CHARGER_STAT: get battery presence from chargers.
> +
> +char **psy_charger_stat;

Why do you want to use names here?

> +	: An array ending with NULL that has power-supply-class names of
> +	chargers. Each power-supply-class should provide "PRESENT" (if
> +	battery_present is "CM_CHARGER_STAT"), "ONLINE" (shows whether an
> +	external power source is attached or not), and "STATUS" (shows whether
> +	the battery is {"FULL" or not FULL} or {"FULL", "Charging",
> +	"Discharging", "NotCharging"}).
> +
> +int num_charger_regulators;
> +struct regulator_bulk_data *charger_regulators;
> +	: Regulators representing the chargers in the form for
> +	regulator framework's bulk functions.
> +
> +char *psy_fuel_gauge;
> +	: Power-supply-class name of the fuel gauge.
> +
> +int (*is_temperature_error)(int *mC);

temperature_out_of_range might be a better name here.

> +	: 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
> +	if it is too cold to charge. With the variable mC, the callback returns
> +	the temperature in 1/1000 of centigrade.
> +};
> +
> +5. Other Considerations
> +=======================
> +
> +At the charger/battery-related events such as battery-pulled-out,
> +charger-pulled-out, charger-inserted, DCIN-over/under-voltage, charger-stopped,
> +and others critical to chargers, the system should be configured to wake up.
> +At least the following should wake up the system from a suspend:
> +a) charger-on/off b) external-power-in/out c) battery-in/out (while charging)
> +
> +It is usually accomplished by configuring the PMIC as a wakeup source.
> +
> diff --git a/drivers/power/Kconfig b/drivers/power/Kconfig
> index 9f88641..92683b5 100644
> --- a/drivers/power/Kconfig
> +++ b/drivers/power/Kconfig
> @@ -236,6 +236,15 @@ config CHARGER_GPIO
>  	  This driver can be build as a module. If so, the module will be
>  	  called gpio-charger.
>  
> +config CHARGER_MANAGER
> +        bool "Battery charger manager for multiple chargers"
> +        help
> +          Say Y to enable charger-manager support, which allows multiple
> +          chargers attached to a battery and multiple batteries attached to a
> +          system. The charger-manager also can monitor charging status in
> +          runtime and in suspend-to-RAM by waking up the system periodically
> +          with help of suspend_again support.
> +
>  config CHARGER_MAX8997
>  	tristate "Maxim MAX8997/MAX8966 PMIC battery charger driver"
>  	depends on MFD_MAX8997 && REGULATOR_MAX8997
> diff --git a/drivers/power/Makefile b/drivers/power/Makefile
> index b4af13d..d3b24e9 100644
> --- a/drivers/power/Makefile
> +++ b/drivers/power/Makefile
> @@ -36,5 +36,6 @@ obj-$(CONFIG_CHARGER_ISP1704)	+= isp1704_charger.o
>  obj-$(CONFIG_CHARGER_MAX8903)	+= max8903_charger.o
>  obj-$(CONFIG_CHARGER_TWL4030)	+= twl4030_charger.o
>  obj-$(CONFIG_CHARGER_GPIO)	+= gpio-charger.o
> +obj-$(CONFIG_CHARGER_MANAGER)	+= charger-manager.o
>  obj-$(CONFIG_CHARGER_MAX8997)	+= max8997_charger.o
>  obj-$(CONFIG_CHARGER_MAX8998)	+= max8998_charger.o
> diff --git a/drivers/power/charger-manager.c b/drivers/power/charger-manager.c
> new file mode 100644
> index 0000000..5006756
> --- /dev/null
> +++ b/drivers/power/charger-manager.c
> @@ -0,0 +1,771 @@
> +/* linux/drivers/power/charger-manager.c
> + *
> + * Copyright (C) 2011 Samsung Electronics Co., Ltd.
> + * MyungJoo Ham <myungjoo.ham@...sung.com>
> + *
> + * This driver enables to monitor battery health and control charger
> + * during suspend-to-mem.
> + * Charger manager depends on other devices. register this later than
> + * the depending devices.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> +**/
> +
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/irq.h>
> +#include <linux/interrupt.h>
> +#include <linux/rtc.h>
> +#include <linux/slab.h>
> +#include <linux/workqueue.h>
> +#include <linux/platform_device.h>
> +#include <linux/power/charger-manager.h>
> +#include <linux/regulator/consumer.h>
> +
> +/*
> + * Regard CM_JIFFIES_SMALL jiffies is small enough to ignore for
> + * delayed works so that we can run delayed works with CM_JIFFIES_SMALL
> + * without any delays.
> + */
> +#define	CM_JIFFIES_SMALL	(2)

Why do you want to use jiffies instead of ktime?

> +
> +/* If y is valid (> 0) and smaller than x, do x = y */
> +#define CM_MIN_VALID(x, y)	x = (((y > 0) && ((x) > (y))) ? (y) : (x))
> +
> +/*
> + * Regard CM_RTC_SMALL (sec) is small enough to ignore error in invoking
> + * rtc alarm. It should be 2 or larger
> + */
> +#define CM_RTC_SMALL		(2)
> +
> +#define UEVENT_BUF_SIZE		32
> +
> +static LIST_HEAD(cm_list);
> +static DEFINE_MUTEX(cm_list_mtx);
> +
> +/* About in-suspend (suspend-again) monitoring */
> +static struct rtc_device *rtc_dev;
> +static struct rtc_wkalrm rtc_wkalarm_save; /* Backup RTC alarm */
> +static unsigned long rtc_wkalarm_save_; /* 0 if not available */

Those two fields require more explanation or the names should reflect what
they are for (preferably both).

> +static bool cm_suspended;
> +static bool cm_rtc_set;
> +static unsigned long cm_suspend_duration_ms;
> +
> +/* Global charger-manager description */
> +static struct charger_global_desc *g_desc; /* init with setup_charger_manager */
> +
> +/**
> + * is_batt_present - See if the battery presents in place.
> + * @cm: the Charger Manager representing the battery.
> + */
> +static bool is_batt_present(struct charger_manager *cm)
> +{
> +	union power_supply_propval val;
> +	bool present = false;
> +	int i, ret;
> +
> +	switch (cm->desc->battery_present) {
> +	case CM_FUEL_GAUGE:
> +		ret = cm->fuel_gauge->get_property(cm->fuel_gauge,
> +				POWER_SUPPLY_PROP_PRESENT, &val);
> +		if (ret == 0 && val.intval)
> +			present = true;
> +		break;
> +	case CM_CHARGER_STAT:
> +		for (i = 0; cm->charger_stat[i]; i++) {
> +			ret = cm->charger_stat[i]->get_property(
> +					cm->charger_stat[i],
> +					POWER_SUPPLY_PROP_PRESENT, &val);
> +			if (ret == 0 && val.intval) {
> +				present = true;
> +				break;
> +			}
> +		}
> +		break;
> +	}
> +
> +	return present;
> +}
> +
> +/**
> + * is_ext_pwr_online - See if an external power source is attached to charge
> + * @cm: the Charger Manager representing the battery.
> + *
> + * Returns true if at least one of the chargers of the battery has an external
> + * power source attached to charge the battery regardless of whether it is
> + * actually charging or not.
> + */
> +static bool is_ext_pwr_online(struct charger_manager *cm)
> +{
> +	union power_supply_propval val;
> +	bool online = false;
> +	int i, ret;
> +
> +	/* If at least one of them has one, it's yes. */
> +	for (i = 0; cm->charger_stat[i]; i++) {
> +		ret = cm->charger_stat[i]->get_property(
> +				cm->charger_stat[i],
> +				POWER_SUPPLY_PROP_ONLINE, &val);
> +		if (ret == 0 && val.intval) {
> +			online = true;
> +			break;
> +		}
> +	}
> +
> +	return online;
> +}
> +
> +/**
> + * is_charging - Returns true if the battery is being charged.
> + * @cm: the Charger Manager representing the battery.
> + */
> +static bool is_charging(struct charger_manager *cm)
> +{
> +	int i, ret;
> +	bool charging = false;
> +	union power_supply_propval val;
> +
> +	/* If there is no battery, it cannot be charged */
> +	if (!is_batt_present(cm))
> +		return false;
> +
> +	/* If at least one of the charger is charging, return yes */
> +	for (i = 0; cm->charger_stat[i]; i++) {
> +		/* 1. The charger sholuld not be DISABLED */
> +		if (cm->emergency_stop)
> +			continue;
> +		if (!cm->charger_enabled)
> +			continue;
> +
> +		/* 2. The charger should be online (ext-power) */
> +		ret = cm->charger_stat[i]->get_property(
> +				cm->charger_stat[i],
> +				POWER_SUPPLY_PROP_ONLINE, &val);
> +		if (ret) {
> +			dev_warn(cm->dev, "Cannot read ONLINE value from %s.\n",
> +					cm->desc->psy_charger_stat[i]);
> +			continue;
> +		}
> +		if (val.intval == 0)
> +			continue;
> +
> +		/*
> +		 * 3. The charger should not be FULL, DISCHARGING,
> +		 * or NOT_CHARGING.
> +		 */
> +		ret = cm->charger_stat[i]->get_property(
> +				cm->charger_stat[i],
> +				POWER_SUPPLY_PROP_STATUS, &val);
> +		if (ret) {
> +			dev_warn(cm->dev, "Cannot read STATUS value from %s.\n",
> +					cm->desc->psy_charger_stat[i]);
> +			continue;
> +		}
> +		if (val.intval == POWER_SUPPLY_STATUS_FULL ||
> +				val.intval == POWER_SUPPLY_STATUS_DISCHARGING ||
> +				val.intval == POWER_SUPPLY_STATUS_NOT_CHARGING)
> +			continue;
> +
> +		/* Then, this is charging. */
> +		charging = true;
> +		break;
> +	}
> +
> +	return charging;
> +}
> +
> +/**
> + * is_polling_required - Return true if need to continue polling for this CM.
> + * @cm: the Charger Manager representing the battery.
> + */
> +static bool is_polling_required(struct charger_manager *cm)
> +{
> +	switch (cm->desc->polling_mode) {
> +	case CM_POLL_DISABLE:
> +		return false;
> +	case CM_POLL_ALWAYS:
> +		return true;
> +	case CM_POLL_EXTERNAL_POWER_ONLY:
> +		return is_ext_pwr_online(cm);
> +	case CM_POLL_CHARGING_ONLY:
> +		return is_charging(cm);
> +	default:
> +		dev_warn(cm->dev, "Incorrect polling_mode (%d)\n",
> +			cm->desc->polling_mode);
> +	}
> +
> +	return false;
> +}
> +
> +/**
> + * try_charger_enable - Enable/Disable chargers altogether
> + * @cm: the Charger Manager representing the battery.
> + * @enable: true: enable / false: disable
> + *
> + * Note that Charger Manager keeps the charger enabled regardless whether
> + * the charger is charging or not (because battery is full or no external
> + * power source exists) except when CM needs to disable chargers forcibly
> + * bacause of emergency causes; when the battery is overheated or too cold.
> + */
> +static int try_charger_enable(struct charger_manager *cm, bool enable)
> +{
> +	int err = 0, i;
> +	struct charger_desc *desc = cm->desc;
> +
> +	/* Ignore if it's redundent command */
> +	if (enable && cm->charger_enabled)
> +		return 0;
> +	if (!enable && !cm->charger_enabled)
> +		return 0;
> +
> +	if (enable) {
> +		if (cm->emergency_stop)
> +			return -EAGAIN;
> +		err = regulator_bulk_enable(desc->num_charger_regulators,
> +					desc->charger_regulators);
> +	} else {
> +		/*
> +		 * Abnormal battery state - Stop charging forcibly,
> +		 * even if charger was enabled at the other places
> +		 */
> +		err = regulator_bulk_disable(desc->num_charger_regulators,
> +					desc->charger_regulators);
> +
> +		for (i = 0; i < desc->num_charger_regulators; i++) {
> +			if (regulator_is_enabled(
> +				    desc->charger_regulators[i].consumer)) {
> +				regulator_force_disable(
> +					desc->charger_regulators[i].consumer);
> +				dev_warn(cm->dev,
> +					"Disable regulator(%s) forcibly.\n",
> +					desc->charger_regulators[i].supply);
> +			}
> +		}
> +	}
> +
> +	if (!err)
> +		cm->charger_enabled = enable;
> +
> +	return err;
> +}
> +
> +/**
> + * uevent_notify - Let users know something has changed.
> + * @cm: the Charger Manager representing the battery.
> + * @event: the event string.
> + *
> + * If @event is null, it implies that uevent_notify is called
> + * by resume function. When called in the resume function, cm_suspended
> + * should be already reset to false in order to let uevent_notify
> + * notify the recent event during the suspend to users. While
> + * suspended, uevent_notify does not notify users, but tracks
> + * events so that uevent_notify can notify users later after resumed.
> + */
> +static void uevent_notify(struct charger_manager *cm, const char *event)
> +{
> +	static char env_str[UEVENT_BUF_SIZE + 1] = "";
> +	static char env_str_save[UEVENT_BUF_SIZE + 1] = "";
> +
> +	if (cm_suspended) {
> +		/* Nothing in suspended-event buffer */
> +		if (env_str_save[0] == 0) {
> +			if (!strncmp(env_str, event, UEVENT_BUF_SIZE))
> +				return; /* status not changed */
> +			strncpy(env_str_save, event, UEVENT_BUF_SIZE);
> +			return;
> +		}
> +
> +		if (!strncmp(env_str_save, event, UEVENT_BUF_SIZE))
> +			return; /* Duplicated. */
> +		else
> +			strncpy(env_str_save, event, UEVENT_BUF_SIZE);
> +
> +		return;
> +	}
> +
> +	if (event == NULL) {
> +		/* No messages pending */
> +		if (!env_str_save[0])
> +			return;
> +
> +		strncpy(env_str, env_str_save, UEVENT_BUF_SIZE);
> +		kobject_uevent(&cm->dev->kobj, KOBJ_CHANGE);
> +		env_str_save[0] = 0;
> +
> +		return;
> +	}
> +
> +	/* status not changed */
> +	if (!strncmp(env_str, event, UEVENT_BUF_SIZE))
> +		return;
> +
> +	/* save the status and notify the update */
> +	strncpy(env_str, event, UEVENT_BUF_SIZE);
> +	kobject_uevent(&cm->dev->kobj, KOBJ_CHANGE);
> +
> +	dev_info(cm->dev, event);
> +}
> +
> +/**
> + * _cm_monitor - Monitor the temperature and return true for exceptions.
> + * @cm: the Charger Manager representing the battery.
> + *
> + * Returns true if there is an event to notify for the battery.
> + * (True if the status of "emergency_stop" changes)
> + */
> +static bool _cm_monitor(struct charger_manager *cm)
> +{
> +	struct charger_desc *desc = cm->desc;
> +	int temp = desc->is_temperature_error(&cm->last_temp_mC);
> +
> +	dev_dbg(cm->dev, "monitoring (%2.2d.%3.3dC)\n",
> +		cm->last_temp_mC / 1000, cm->last_temp_mC % 1000);
> +
> +	/* It has been stopped already */
> +	if (temp && cm->emergency_stop)
> +		return false;
> +
> +	/* It has been charging already */
> +	if (!temp && !cm->emergency_stop)
> +		return false;
> +

The above two statements may be written as one in the following form:

if (!!temp == !!cm->emergency_stop)
	return false;

> +	if (temp) {
> +		cm->emergency_stop = temp;
> +		if (!try_charger_enable(cm, false)) {
> +			if (temp > 0)
> +				uevent_notify(cm, "OVERHEAT");
> +			else
> +				uevent_notify(cm, "COLD");
> +		}
> +	} else {
> +		cm->emergency_stop = 0;
> +		if (!try_charger_enable(cm, true))
> +			uevent_notify(cm, "CHARGING");
> +	}
> +
> +	return true;
> +}
> +
> +/**
> + * cm_monitor - Monitor every battery.
> + *
> + * Returns true if there is an event to notify from any of the batteries.
> + * (True if the status of "emergency_stop" changes)
> + */
> +static bool cm_monitor(void)
> +{
> +	bool stop = false;
> +	struct charger_manager *cm;
> +
> +	mutex_lock(&cm_list_mtx);
> +
> +	list_for_each_entry(cm, &cm_list, entry)
> +		stop |= _cm_monitor(cm);
> +

That should be

		stop ||= _cm_monitor(cm);

it appears.

> +	mutex_unlock(&cm_list_mtx);
> +
> +	return stop;
> +}
> +
> +/**
> + * cm_setup_timer - For in-suspend monitoring setup wakeup alarm
> + *		    for suspend_again.
> + *
> + * Returns true if the alarm is set for Charger Manager to use.
> + * Returns false if
> + *	cm_setup_timer fails to set an alarm,
> + *	cm_setup_timer does not need to set an alarm for Charger Manager,
> + *	or an alarm previously configured is to be used.
> + */
> +static bool cm_setup_timer(void)
> +{
> +	struct charger_manager *cm;
> +	unsigned int wakeup_ms = UINT_MAX;
> +	bool ret = false;
> +
> +	mutex_lock(&cm_list_mtx);
> +
> +	list_for_each_entry(cm, &cm_list, entry) {
> +		/* Skip if polling is not required for this CM */
> +		if (!is_polling_required(cm) && !cm->emergency_stop)
> +			continue;
> +		if (cm->desc->polling_interval_ms == 0)
> +			continue;
> +		CM_MIN_VALID(wakeup_ms, cm->desc->polling_interval_ms);
> +	}
> +
> +	mutex_unlock(&cm_list_mtx);
> +
> +	if (wakeup_ms < UINT_MAX && wakeup_ms > 0) {
> +		pr_info("Charger Manager wakeup timer: %u ms.\n", wakeup_ms);
> +		if (rtc_dev) {
> +			struct rtc_wkalrm tmp;
> +			unsigned long time, now;
> +			unsigned long add = DIV_ROUND_UP(wakeup_ms, 1000);
> +
> +			/*
> +			 * Set alarm with the polling interval (wakeup_ms)
> +			 * except when rtc_wkalarm_save comes first.
> +			 * However, the alarm time should be NOW +
> +			 * CM_RTC_SMALL or later.
> +			 */
> +			tmp.enabled = 1;
> +			rtc_read_time(rtc_dev, &tmp.time);
> +			rtc_tm_to_time(&tmp.time, &now);
> +			if (add < CM_RTC_SMALL)
> +				add = CM_RTC_SMALL;
> +			time = now + add;
> +
> +			ret = true;
> +
> +			if (rtc_wkalarm_save.enabled && rtc_wkalarm_save_ &&
> +			    rtc_wkalarm_save_ < time) {
> +				if (rtc_wkalarm_save_ < now + CM_RTC_SMALL)
> +					time = now + CM_RTC_SMALL;
> +				else
> +					time = rtc_wkalarm_save_;
> +
> +				/* The timer is not appointed by CM */
> +				ret = false;
> +			}
> +
> +			pr_info("Waking up after %lu secs.\n",
> +					time - now);
> +
> +			rtc_time_to_tm(time, &tmp.time);
> +			rtc_set_alarm(rtc_dev, &tmp);
> +			cm_suspend_duration_ms += wakeup_ms;
> +			return ret;
> +		}
> +	}
> +
> +	if (rtc_dev)
> +		rtc_set_alarm(rtc_dev, &rtc_wkalarm_save);
> +	return false;
> +}
> +
> +/**
> + * cm_suspend_again - Determine whether suspend again or not
> + *
> + * Returns true if the system should be suspended again
> + * Returns false if the system should be woken up
> + */
> +bool cm_suspend_again(void)
> +{
> +	struct charger_manager *cm;
> +	bool ret = false;
> +
> +	if (!g_desc)
> +		return false;
> +	if (!g_desc->is_rtc_only_wakeup_reason)
> +		return false;
> +	if (!g_desc->is_rtc_only_wakeup_reason())
> +		return false;
> +	if (!cm_rtc_set)
> +		return false;

Use || and write the above as one statement, perhaps?

> +
> +	if (cm_monitor())
> +		goto out;
> +
> +	ret = true;
> +	mutex_lock(&cm_list_mtx);
> +	list_for_each_entry(cm, &cm_list, entry) {
> +		if (cm->status_save_ext_pwr_inserted != is_ext_pwr_online(cm) ||
> +		    cm->status_save_batt != is_batt_present(cm))
> +			ret = false;
> +	}
> +	mutex_unlock(&cm_list_mtx);
> +
> +	cm_rtc_set = cm_setup_timer();
> +out:
> +	/* It's about the time when the non-CM appointed timer goes off */
> +	if (rtc_wkalarm_save.enabled) {
> +		unsigned long now;
> +		struct rtc_time tmp;
> +
> +		rtc_read_time(rtc_dev, &tmp);
> +		rtc_tm_to_time(&tmp, &now);
> +
> +		if (rtc_wkalarm_save_ &&
> +		    now + CM_RTC_SMALL >= rtc_wkalarm_save_)
> +			return false;
> +	}
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(cm_suspend_again);
> +
> +/**
> + * setup_charger_manager - initialize charger_global_desc data
> + * @gd: pointer to instance of charger_global_desc
> + */
> +int setup_charger_manager(struct charger_global_desc *gd)
> +{
> +	if (!gd)
> +		return -EINVAL;
> +
> +	if (rtc_dev)
> +		rtc_class_close(rtc_dev);
> +	rtc_dev = NULL;
> +	g_desc = NULL;
> +
> +	if (!gd->is_rtc_only_wakeup_reason) {
> +		pr_err("The callback is_wktimer_only_wkreason is not given.\n");
> +		return -EINVAL;
> +	}
> +
> +	if (gd->rtc) {
> +		rtc_dev = rtc_class_open(gd->rtc);
> +		if (IS_ERR_OR_NULL(rtc_dev)) {
> +			rtc_dev = NULL;
> +			/* Retry at probe. RTC may be not registered yet */
> +		}
> +	} else {
> +		pr_warn("No wktimer is given for charger manager."
> +			"In-suspend monitoring won't work.\n");
> +	}
> +
> +	g_desc = gd;
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(setup_charger_manager);
> +
> +static int charger_manager_probe(struct platform_device *pdev)
> +{
> +	struct charger_desc *desc = dev_get_platdata(&pdev->dev);
> +	struct charger_manager *cm;
> +	int ret = 0, i;
> +
> +	if (g_desc && !rtc_dev && g_desc->rtc) {
> +		rtc_dev = rtc_class_open(g_desc->rtc);
> +		if (IS_ERR_OR_NULL(rtc_dev)) {
> +			rtc_dev = NULL;
> +			dev_err(&pdev->dev, "Cannot get RTC %s.\n",
> +				g_desc->rtc);
> +			ret = -ENODEV;
> +			goto err_alloc;
> +		}
> +	}
> +
> +	if (!desc) {
> +		dev_err(&pdev->dev, "No platform data (desc) found.\n");
> +		ret = -ENODEV;
> +		goto err_alloc;
> +	}

Is there any way to detect whether dev_get_platdata(&pdev->dev) really points
to an instance of struct charger_desc ?

> +
> +	cm = kzalloc(sizeof(struct charger_manager), GFP_KERNEL);
> +	if (!cm) {
> +		dev_err(&pdev->dev, "Cannot allocate memory.\n");
> +		ret = -ENOMEM;
> +		goto err_alloc;
> +	}
> +
> +	/* Basic Values. Unspecified are Null or 0 */
> +	cm->dev = &pdev->dev;
> +	cm->desc = desc;
> +	cm->last_temp_mC = INT_MIN; /* denotes "unmeasured, yet" */
> +
> +	if (!desc->charger_regulators || desc->num_charger_regulators < 1) {
> +		ret = -EINVAL;
> +		dev_err(&pdev->dev, "charger_regulators undefined.\n");
> +		goto err_no_charger;
> +	}
> +
> +	ret = regulator_bulk_get(&pdev->dev, desc->num_charger_regulators,
> +				 desc->charger_regulators);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Cannot get charger regulators.\n");
> +		goto err_no_charger;
> +	}
> +
> +	if (!desc->psy_charger_stat || !desc->psy_charger_stat[0]) {
> +		dev_err(&pdev->dev, "No power supply defined.\n");
> +		ret = -EINVAL;
> +		goto err_no_charger_stat;
> +	}

It might be better to check that before calling regulator_bulk_get().

> +
> +	for (i = 0; desc->psy_charger_stat[i]; i++)
> +		/* Counting index only */ ;

In my opinion it would be better to write the above and a while() loop.

Also, that wouldn't be necessary at all if the number of psy_charger_stat
entries were stored in desc.

> +
> +	cm->charger_stat = kzalloc(sizeof(struct power_supply *) * (i + 1),
> +				   GFP_KERNEL);
> +	if (!cm->charger_stat) {
> +		ret = -ENOMEM;
> +		goto err_no_charger_stat;
> +	}
> +
> +	for (i = 0; desc->psy_charger_stat[i]; i++) {
> +		cm->charger_stat[i] = power_supply_get_by_name(
> +					desc->psy_charger_stat[i]);
> +		if (!cm->charger_stat[i]) {
> +			dev_err(&pdev->dev, "Cannot find power supply "
> +					"\"%s\"\n",
> +					desc->psy_charger_stat[i]);
> +			ret = -ENODEV;
> +			goto err_chg_stat;
> +		}
> +	}
> +
> +	cm->fuel_gauge = power_supply_get_by_name(desc->psy_fuel_gauge);
> +	if (!cm->fuel_gauge) {
> +		dev_err(&pdev->dev, "Cannot find power supply \"%s\"\n",
> +				desc->psy_fuel_gauge);
> +		ret = -ENODEV;
> +		goto err_chg_stat;
> +	}
> +
> +	if (desc->polling_interval_ms == 0 ||
> +	    msecs_to_jiffies(desc->polling_interval_ms) <= CM_JIFFIES_SMALL) {
> +		dev_err(&pdev->dev, "polling_interval_ms is too small\n");
> +		ret = -EINVAL;
> +		goto err_chg_stat;
> +	}
> +
> +	if (!desc->is_temperature_error) {
> +		dev_err(&pdev->dev, "there is no is_temperature_error\n");
> +		ret = -EINVAL;
> +		goto err_chg_stat;
> +	}
> +
> +	platform_set_drvdata(pdev, cm);
> +
> +	ret = try_charger_enable(cm, true);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Cannot enable charger regulators\n");
> +		goto err_chg_stat;
> +	}
> +
> +	/* Add to the list */
> +	mutex_lock(&cm_list_mtx);
> +	list_add(&cm->entry, &cm_list);
> +	mutex_unlock(&cm_list_mtx);
> +
> +	return 0;
> +
> +err_chg_stat:
> +	kfree(cm->charger_stat);
> +err_no_charger_stat:
> +	if (desc->charger_regulators)
> +		regulator_bulk_free(desc->num_charger_regulators,
> +					desc->charger_regulators);
> +err_no_charger:
> +	kfree(cm);
> +err_alloc:
> +	return ret;
> +}
> +
> +static int __devexit charger_manager_remove(struct platform_device *pdev)
> +{
> +	struct charger_manager *cm = platform_get_drvdata(pdev);
> +	struct charger_desc *desc = cm->desc;
> +
> +	/* Remove from the list */
> +	mutex_lock(&cm_list_mtx);
> +	list_del(&cm->entry);
> +	mutex_unlock(&cm_list_mtx);
> +
> +	kfree(cm->charger_stat);
> +	if (desc->charger_regulators)
> +		regulator_bulk_free(desc->num_charger_regulators,
> +					desc->charger_regulators);
> +	kfree(cm);
> +	return 0;
> +}
> +
> +const struct platform_device_id charger_manager_id[] = {
> +	{ "charger-manager", 0 },
> +	{ },
> +};
> +

The prepare/complete routines look good to me.

Thanks,
Rafael
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