diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2012-01-11 21:53:05 -0500 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-01-11 21:53:05 -0500 |
commit | b24ca57e7625bc304e77bc429693ad32a691eb16 (patch) | |
tree | 770aa389c6e763cf37776a35e85ff1e41958b1e9 /Documentation/power | |
parent | 6296e5d3c067df41980a5fd09ad4cc6765f79bb9 (diff) | |
parent | 913272b3864d6da89c70d9fc2c30ccb57794b369 (diff) |
Merge git://git.infradead.org/battery-2.6
* git://git.infradead.org/battery-2.6: (68 commits)
power_supply: Mark da9052 driver as broken
power_supply: Drop usage of nowarn variant of sysfs_create_link()
s3c_adc_battery: Average over more than one adc sample
power_supply: Add DA9052 battery driver
isp1704_charger: Fix missing check
jz4740-battery: Fix signedness bug
power_supply: Assume mains power by default
sbs-battery: Fix devicetree match table
ARM: rx51: Add bq27200 i2c board info
sbs-battery: Change power supply name
devicetree-bindings: Propagate bq20z75->sbs rename to dt bindings
devicetree-bindings: Add vendor entry for Smart Battery Systems
sbs-battery: Rename internals to new name
bq20z75: Rename to sbs-battery
wm97xx_battery: Use DEFINE_MUTEX() for work_lock
max8997_charger: Remove duplicate module.h
lp8727_charger: Some minor fixes for the header
lp8727_charger: Add header file
power_supply: Convert drivers/power/* to use module_platform_driver()
power_supply: Add "unknown" in power supply type
...
Diffstat (limited to 'Documentation/power')
-rw-r--r-- | Documentation/power/charger-manager.txt | 163 |
1 files changed, 163 insertions, 0 deletions
diff --git a/Documentation/power/charger-manager.txt b/Documentation/power/charger-manager.txt new file mode 100644 index 000000000000..fdcca991df30 --- /dev/null +++ b/Documentation/power/charger-manager.txt | |||
@@ -0,0 +1,163 @@ | |||
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 | 2. Global Charger-Manager Data related with suspend_again | ||
48 | ======================================================== | ||
49 | In order to setup Charger Manager with suspend-again feature | ||
50 | (in-suspend monitoring), the user should provide charger_global_desc | ||
51 | with setup_charger_manager(struct charger_global_desc *). | ||
52 | This charger_global_desc data for in-suspend monitoring is global | ||
53 | as the name suggests. Thus, the user needs to provide only once even | ||
54 | if there are multiple batteries. If there are multiple batteries, the | ||
55 | multiple instances of Charger Manager share the same charger_global_desc | ||
56 | and it will manage in-suspend monitoring for all instances of Charger Manager. | ||
57 | |||
58 | The user needs to provide all the two entries properly in order to activate | ||
59 | in-suspend monitoring: | ||
60 | |||
61 | struct charger_global_desc { | ||
62 | |||
63 | char *rtc_name; | ||
64 | : The name of rtc (e.g., "rtc0") used to wakeup the system from | ||
65 | suspend for Charger Manager. The alarm interrupt (AIE) of the rtc | ||
66 | should be able to wake up the system from suspend. Charger Manager | ||
67 | saves and restores the alarm value and use the previously-defined | ||
68 | alarm if it is going to go off earlier than Charger Manager so that | ||
69 | Charger Manager does not interfere with previously-defined alarms. | ||
70 | |||
71 | bool (*rtc_only_wakeup)(void); | ||
72 | : This callback should let CM know whether | ||
73 | the wakeup-from-suspend is caused only by the alarm of "rtc" in the | ||
74 | same struct. If there is any other wakeup source triggered the | ||
75 | wakeup, it should return false. If the "rtc" is the only wakeup | ||
76 | reason, it should return true. | ||
77 | }; | ||
78 | |||
79 | 3. How to setup suspend_again | ||
80 | ============================= | ||
81 | Charger Manager provides a function "extern bool cm_suspend_again(void)". | ||
82 | When cm_suspend_again is called, it monitors every battery. The suspend_ops | ||
83 | callback of the system's platform_suspend_ops can call cm_suspend_again | ||
84 | function to know whether Charger Manager wants to suspend again or not. | ||
85 | If there are no other devices or tasks that want to use suspend_again | ||
86 | feature, the platform_suspend_ops may directly refer to cm_suspend_again | ||
87 | for its suspend_again callback. | ||
88 | |||
89 | The cm_suspend_again() returns true (meaning "I want to suspend again") | ||
90 | if the system was woken up by Charger Manager and the polling | ||
91 | (in-suspend monitoring) results in "normal". | ||
92 | |||
93 | 4. Charger-Manager Data (struct charger_desc) | ||
94 | ============================================= | ||
95 | For each battery charged independently from other batteries (if a series of | ||
96 | batteries are charged by a single charger, they are counted as one independent | ||
97 | battery), an instance of Charger Manager is attached to it. | ||
98 | |||
99 | struct charger_desc { | ||
100 | |||
101 | char *psy_name; | ||
102 | : The power-supply-class name of the battery. Default is | ||
103 | "battery" if psy_name is NULL. Users can access the psy entries | ||
104 | at "/sys/class/power_supply/[psy_name]/". | ||
105 | |||
106 | enum polling_modes polling_mode; | ||
107 | : CM_POLL_DISABLE: do not poll this battery. | ||
108 | CM_POLL_ALWAYS: always poll this battery. | ||
109 | CM_POLL_EXTERNAL_POWER_ONLY: poll this battery if and only if | ||
110 | an external power source is attached. | ||
111 | CM_POLL_CHARGING_ONLY: poll this battery if and only if the | ||
112 | battery is being charged. | ||
113 | |||
114 | unsigned int fullbatt_uV; | ||
115 | : If specified with a non-zero value, Charger Manager assumes | ||
116 | that the battery is full (capacity = 100) if the battery is not being | ||
117 | charged and the battery voltage is equal to or greater than | ||
118 | fullbatt_uV. | ||
119 | |||
120 | unsigned int polling_interval_ms; | ||
121 | : Required polling interval in ms. Charger Manager will poll | ||
122 | this battery every polling_interval_ms or more frequently. | ||
123 | |||
124 | enum data_source battery_present; | ||
125 | CM_FUEL_GAUGE: get battery presence information from fuel gauge. | ||
126 | CM_CHARGER_STAT: get battery presence from chargers. | ||
127 | |||
128 | char **psy_charger_stat; | ||
129 | : An array ending with NULL that has power-supply-class names of | ||
130 | chargers. Each power-supply-class should provide "PRESENT" (if | ||
131 | battery_present is "CM_CHARGER_STAT"), "ONLINE" (shows whether an | ||
132 | external power source is attached or not), and "STATUS" (shows whether | ||
133 | the battery is {"FULL" or not FULL} or {"FULL", "Charging", | ||
134 | "Discharging", "NotCharging"}). | ||
135 | |||
136 | int num_charger_regulators; | ||
137 | struct regulator_bulk_data *charger_regulators; | ||
138 | : Regulators representing the chargers in the form for | ||
139 | regulator framework's bulk functions. | ||
140 | |||
141 | char *psy_fuel_gauge; | ||
142 | : Power-supply-class name of the fuel gauge. | ||
143 | |||
144 | int (*temperature_out_of_range)(int *mC); | ||
145 | bool measure_battery_temp; | ||
146 | : This callback returns 0 if the temperature is safe for charging, | ||
147 | a positive number if it is too hot to charge, and a negative number | ||
148 | if it is too cold to charge. With the variable mC, the callback returns | ||
149 | the temperature in 1/1000 of centigrade. | ||
150 | The source of temperature can be battery or ambient one according to | ||
151 | the value of measure_battery_temp. | ||
152 | }; | ||
153 | |||
154 | 5. Other Considerations | ||
155 | ======================= | ||
156 | |||
157 | At the charger/battery-related events such as battery-pulled-out, | ||
158 | charger-pulled-out, charger-inserted, DCIN-over/under-voltage, charger-stopped, | ||
159 | and others critical to chargers, the system should be configured to wake up. | ||
160 | At least the following should wake up the system from a suspend: | ||
161 | a) charger-on/off b) external-power-in/out c) battery-in/out (while charging) | ||
162 | |||
163 | It is usually accomplished by configuring the PMIC as a wakeup source. | ||