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Based on kernel version 3.13. Page generated on 2014-01-20 22:04 EST.

1	Charger Manager
2		(C) 2011 MyungJoo Ham <myungjoo.ham@samsung.com>, GPL
3	
4	Charger Manager provides in-kernel battery charger management that
5	requires temperature monitoring during suspend-to-RAM state
6	and where each battery may have multiple chargers attached and the userland
7	wants to look at the aggregated information of the multiple chargers.
8	
9	Charger Manager is a platform_driver with power-supply-class entries.
10	An instance of Charger Manager (a platform-device created with Charger-Manager)
11	represents an independent battery with chargers. If there are multiple
12	batteries with their own chargers acting independently in a system,
13	the system may need multiple instances of Charger Manager.
14	
15	1. Introduction
16	===============
17	
18	Charger Manager supports the following:
19	
20	* Support for multiple chargers (e.g., a device with USB, AC, and solar panels)
21		A system may have multiple chargers (or power sources) and some of
22		they may be activated at the same time. Each charger may have its
23		own power-supply-class and each power-supply-class can provide
24		different information about the battery status. This framework
25		aggregates charger-related information from multiple sources and
26		shows combined information as a single power-supply-class.
27	
28	* Support for in suspend-to-RAM polling (with suspend_again callback)
29		While the battery is being charged and the system is in suspend-to-RAM,
30		we may need to monitor the battery health by looking at the ambient or
31		battery temperature. We can accomplish this by waking up the system
32		periodically. However, such a method wakes up devices unncessary for
33		monitoring the battery health and tasks, and user processes that are
34		supposed to be kept suspended. That, in turn, incurs unnecessary power
35		consumption and slow down charging process. Or even, such peak power
36		consumption can stop chargers in the middle of charging
37		(external power input < device power consumption), which not
38		only affects the charging time, but the lifespan of the battery.
39	
40		Charger Manager provides a function "cm_suspend_again" that can be
41		used as suspend_again callback of platform_suspend_ops. If the platform
42		requires tasks other than cm_suspend_again, it may implement its own
43		suspend_again callback that calls cm_suspend_again in the middle.
44		Normally, the platform will need to resume and suspend some devices
45		that are used by Charger Manager.
46	
47	* Support for premature full-battery event handling
48		If the battery voltage drops by "fullbatt_vchkdrop_uV" after
49		"fullbatt_vchkdrop_ms" from the full-battery event, the framework
50		restarts charging. This check is also performed while suspended by
51		setting wakeup time accordingly and using suspend_again.
52	
53	* Support for uevent-notify
54		With the charger-related events, the device sends
55		notification to users with UEVENT.
56	
57	2. Global Charger-Manager Data related with suspend_again
58	========================================================
59	In order to setup Charger Manager with suspend-again feature
60	(in-suspend monitoring), the user should provide charger_global_desc
61	with setup_charger_manager(struct charger_global_desc *).
62	This charger_global_desc data for in-suspend monitoring is global
63	as the name suggests. Thus, the user needs to provide only once even
64	if there are multiple batteries. If there are multiple batteries, the
65	multiple instances of Charger Manager share the same charger_global_desc
66	and it will manage in-suspend monitoring for all instances of Charger Manager.
67	
68	The user needs to provide all the three entries properly in order to activate
69	in-suspend monitoring:
70	
71	struct charger_global_desc {
72	
73	char *rtc_name;
74		: The name of rtc (e.g., "rtc0") used to wakeup the system from
75		suspend for Charger Manager. The alarm interrupt (AIE) of the rtc
76		should be able to wake up the system from suspend. Charger Manager
77		saves and restores the alarm value and use the previously-defined
78		alarm if it is going to go off earlier than Charger Manager so that
79		Charger Manager does not interfere with previously-defined alarms.
80	
81	bool (*rtc_only_wakeup)(void);
82		: This callback should let CM know whether
83		the wakeup-from-suspend is caused only by the alarm of "rtc" in the
84		same struct. If there is any other wakeup source triggered the
85		wakeup, it should return false. If the "rtc" is the only wakeup
86		reason, it should return true.
87	
88	bool assume_timer_stops_in_suspend;
89		: if true, Charger Manager assumes that
90		the timer (CM uses jiffies as timer) stops during suspend. Then, CM
91		assumes that the suspend-duration is same as the alarm length.
92	};
93	
94	3. How to setup suspend_again
95	=============================
96	Charger Manager provides a function "extern bool cm_suspend_again(void)".
97	When cm_suspend_again is called, it monitors every battery. The suspend_ops
98	callback of the system's platform_suspend_ops can call cm_suspend_again
99	function to know whether Charger Manager wants to suspend again or not.
100	If there are no other devices or tasks that want to use suspend_again
101	feature, the platform_suspend_ops may directly refer to cm_suspend_again
102	for its suspend_again callback.
103	
104	The cm_suspend_again() returns true (meaning "I want to suspend again")
105	if the system was woken up by Charger Manager and the polling
106	(in-suspend monitoring) results in "normal".
107	
108	4. Charger-Manager Data (struct charger_desc)
109	=============================================
110	For each battery charged independently from other batteries (if a series of
111	batteries are charged by a single charger, they are counted as one independent
112	battery), an instance of Charger Manager is attached to it.
113	
114	struct charger_desc {
115	
116	char *psy_name;
117		: The power-supply-class name of the battery. Default is
118		"battery" if psy_name is NULL. Users can access the psy entries
119		at "/sys/class/power_supply/[psy_name]/".
120	
121	enum polling_modes polling_mode;
122		: CM_POLL_DISABLE: do not poll this battery.
123		  CM_POLL_ALWAYS: always poll this battery.
124		  CM_POLL_EXTERNAL_POWER_ONLY: poll this battery if and only if
125					       an external power source is attached.
126		  CM_POLL_CHARGING_ONLY: poll this battery if and only if the
127					 battery is being charged.
128	
129	unsigned int fullbatt_vchkdrop_ms;
130	unsigned int fullbatt_vchkdrop_uV;
131		: If both have non-zero values, Charger Manager will check the
132		battery voltage drop fullbatt_vchkdrop_ms after the battery is fully
133		charged. If the voltage drop is over fullbatt_vchkdrop_uV, Charger
134		Manager will try to recharge the battery by disabling and enabling
135		chargers. Recharge with voltage drop condition only (without delay
136		condition) is needed to be implemented with hardware interrupts from
137		fuel gauges or charger devices/chips.
138	
139	unsigned int fullbatt_uV;
140		: If specified with a non-zero value, Charger Manager assumes
141		that the battery is full (capacity = 100) if the battery is not being
142		charged and the battery voltage is equal to or greater than
143		fullbatt_uV.
144	
145	unsigned int polling_interval_ms;
146		: Required polling interval in ms. Charger Manager will poll
147		this battery every polling_interval_ms or more frequently.
148	
149	enum data_source battery_present;
150		: CM_BATTERY_PRESENT: assume that the battery exists.
151		CM_NO_BATTERY: assume that the battery does not exists.
152		CM_FUEL_GAUGE: get battery presence information from fuel gauge.
153		CM_CHARGER_STAT: get battery presence from chargers.
154	
155	char **psy_charger_stat;
156		: An array ending with NULL that has power-supply-class names of
157		chargers. Each power-supply-class should provide "PRESENT" (if
158		battery_present is "CM_CHARGER_STAT"), "ONLINE" (shows whether an
159		external power source is attached or not), and "STATUS" (shows whether
160		the battery is {"FULL" or not FULL} or {"FULL", "Charging",
161		"Discharging", "NotCharging"}).
162	
163	int num_charger_regulators;
164	struct regulator_bulk_data *charger_regulators;
165		: Regulators representing the chargers in the form for
166		regulator framework's bulk functions.
167	
168	char *psy_fuel_gauge;
169		: Power-supply-class name of the fuel gauge.
170	
171	int (*temperature_out_of_range)(int *mC);
172	bool measure_battery_temp;
173		: This callback returns 0 if the temperature is safe for charging,
174		a positive number if it is too hot to charge, and a negative number
175		if it is too cold to charge. With the variable mC, the callback returns
176		the temperature in 1/1000 of centigrade.
177		The source of temperature can be battery or ambient one according to
178		the value of measure_battery_temp.
179	};
180	
181	5. Notify Charger-Manager of charger events: cm_notify_event()
182	=========================================================
183	If there is an charger event is required to notify
184	Charger Manager, a charger device driver that triggers the event can call
185	cm_notify_event(psy, type, msg) to notify the corresponding Charger Manager.
186	In the function, psy is the charger driver's power_supply pointer, which is
187	associated with Charger-Manager. The parameter "type"
188	is the same as irq's type (enum cm_event_types). The event message "msg" is
189	optional and is effective only if the event type is "UNDESCRIBED" or "OTHERS".
190	
191	6. Other Considerations
192	=======================
193	
194	At the charger/battery-related events such as battery-pulled-out,
195	charger-pulled-out, charger-inserted, DCIN-over/under-voltage, charger-stopped,
196	and others critical to chargers, the system should be configured to wake up.
197	At least the following should wake up the system from a suspend:
198	a) charger-on/off b) external-power-in/out c) battery-in/out (while charging)
199	
200	It is usually accomplished by configuring the PMIC as a wakeup source.
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