Android 键盘驱动
在准备做android键盘驱动之前先整理一下资料：
Keymaps and Keyboard Input
In this document
Functionality Key Layout Map Key Character Map Implementing Your Own Driver (Driver Template) Sample ImplementationThis document describes how keyboard input gets translated into Android actions and how you can customize key layout and key character maps to match the needs of your own device.
Android uses the standard Linux input event device (/dev/event0) and driver as described in the linux/input.h kernel header file. For more information regarding standard Linux input drivers, please see Linux Input drivers at http://kernel.org.
Functionality
Android's input event device is structured around an interrupt or polling routine that captures the device-specific scancode and converts it to a standard form acceptable to Linux (as defined in input.h) before passing it to the kernel with input_event().
The keymap driver's other primary function is to establish a probe function that sets up the interrupt or polling function, handles hardware initialization, and attaches the driver to the input subsystem with input_register_device().
The table below describes the steps required to translate from keyboard input to application action:
| Step | Action | Explanation |
|---|---|---|
| 1. | Window manager reads key event from Linux keyboard driver. | Events are typically positional. For example, the top-left position on a keypad returns 16 regardless of whether that key is printed with a Q (as on a QWERTY keypad) or an A (as on an AZERTY keypads). This first conversion by the Linux Keyboard Driver yields a scancode (for example, 16). |
| 2. | Window manager maps scancode to keycode. | When the window manager reads a key event out of the driver, it maps the scancode to a keycode using a key layout map file. Typically, the keycode is the primary symbol screen-printed on a key. For example, KEYCODE_DPAD_CENTER is the center button on the five-way navigation control. Even though ALT + G generates a "?" character, KEYCODE_G is the keycode. |
| 3. | Window manager sends both the scancode and the keycode to the application. | Both the scancode and keycode are handled by the view with focus. How the application interprets both depend on the application. |
Key Layout Map
Selection of a Key Layout Map
Key layout maps are installed in /system/usr/keylayout and /data/usr/keylayout.
For each keyboard device xxx, set the android.keylayout.xxx system property (see Building New Device for help setting system properties). If you don't specify a keylayout file, Android will default to /system/usr/keylayout/qwerty.kl.
File Format
Key layout maps are stored on the device as UTF-8 text files and have the following characteristics:
- Comments: The pound symbol (#) denotes a comment and everything after the pound symbol on a line is ignored.
- Whitespace: All empty lines are ignored.
- Key definitions: Key definitions follow the syntax
key SCANCODE KEYCODE [FLAGS...], whereSCANCODEis a number,KEYCODEis defined in your specific keylayout file (android.keylayout.xxx), and potentialFLAGSare defined as follows:- SHIFT: While pressed, the shift key modifier is set
- ALT: While pressed, the alt key modifier is set
- CAPS: While pressed, the caps lock key modifier is set
- WAKE: When this key is pressed while the device is asleep, the device will wake up and the key event gets sent to the app.
- WAKE_DROPPED: When this key is pressed while the device is asleep, the device will wake up and the key event does not get sent to the app.
Example of a Key Layout Map File
The following code comes from android/src/device/product/generic/tuttle2.kl and is an example of a complete key layout file:
# Copyright 2007 Google Inc.key 2 1key 3 2key 4 3key 5 4key 6 5key 7 6key 8 7key 9 8key 10 9key 11 0key 158 BACK WAKE_DROPPEDkey 230 SOFT_RIGHT WAKEkey 60 SOFT_RIGHT WAKEkey 107 ENDCALL WAKE_DROPPEDkey 62 ENDCALL WAKE_DROPPEDkey 229 MENU WAKE_DROPPEDkey 59 MENU WAKE_DROPPEDkey 228 POUNDkey 227 STARkey 231 CALL WAKE_DROPPEDkey 61 CALL WAKE_DROPPEDkey 232 DPAD_CENTER WAKE_DROPPEDkey 108 DPAD_DOWN WAKE_DROPPEDkey 103 DPAD_UP WAKE_DROPPEDkey 102 HOME WAKEkey 105 DPAD_LEFT WAKE_DROPPEDkey 106 DPAD_RIGHT WAKE_DROPPEDkey 115 VOLUME_UPkey 114 VOLUME_DOWNkey 116 POWER WAKEkey 212 SLASHkey 16 Qkey 17 Wkey 18 Ekey 19 Rkey 20 Tkey 21 Ykey 22 Ukey 23 Ikey 24 Okey 25 Pkey 30 Akey 31 Skey 32 Dkey 33 Fkey 34 Gkey 35 Hkey 36 Jkey 37 Kkey 38 Lkey 14 DEL key 44 Zkey 45 Xkey 46 Ckey 47 Vkey 48 Bkey 49 Nkey 50 Mkey 51 COMMAkey 52 PERIODkey 28 NEWLINE key 56 ALT_LEFTkey 42 SHIFT_LEFTkey 215 ATkey 57 SPACEkey 53 SLASHkey 127 SYMkey 100 ALT_LEFTkey 399 GRAVE Key Character Map
Selection of a Key Character Map
Key character maps are installed in /system/usr/keychars and /data/usr/keychars.
For each keyboard device xxx, set the android.keychar.xxx system property to the full path of the desired keychar file. If you don't specify a keychar file, Android will default to /system/usr/keychar/qwerty.kl.
File Format
Key character maps are stored on the device as binary resources in order to reduce loading time. Key character maps have the following characteristics:
- Comments: The pound symbol (#) denotes a comment and everything after the pound symbol on a line is ignored.
- Whitespace: All empty lines are ignored.
- Column definitions: Column definitions follow the syntax
columns MODIFIERS [...], whereMODIFIERSare defined as follows:Character in MODIFIERS Corresponding bit in the modifiers O no modifiers S MODIFIER_SHIFT C MODIFIER_CONTROL L MODIFIER_CAPS_LOCK A MODIFIER_ALT - Key definitions: Key definitions have the syntax
key SCANCODE CHARACTER [...]whereSCANCODEis a number andCHARACTERvalues are either UTF-8 characters in quotation marks (for example, "a") or a numeric value thatstrtolcan parse.
Example of a Key Character Map File
The following code comes from android/src/device/product/generic/tuttle2.kcm and represents a complete key character file:
The type line indicates what kind of keyboard your device implements. Possible types include:
- NUMERIC: A numeric (12-key) keyboard.
- Q14: A keyboard that includes all letters but multiple letters per key.
- QWERTY: A keyboard with all letters and possibly numbers. This option applies to all full keyboard configurations, such as AZERTY.
# Copyright 2007 Google Inc.[type=QWERTY]# keycode base caps fn caps_fn number display_labelA 'a' 'A' '%' 0x00 '%' 'A'B 'b' 'B' '=' 0x00 '=' 'B'C 'c' 'C' '8' 0x00E7 '8' 'C'D 'd' 'D' '5' 0x00 '5' 'D'E 'e' 'E' '2' 0x0301 '2' 'E'F 'f' 'F' '6' 0x00A5 '6' 'F'G 'g' 'G' '-' '_' '-' 'G'H 'h' 'H' '[' '{' '[' 'H'I 'i' 'I' '$' 0x0302 '$' 'I'J 'j' 'J' ']' '}' ']' 'J'K 'k' 'K' '"' '~' '"' 'K'L 'l' 'L' ''' '`' ''' 'L'M 'm' 'M' '>' 0x00 '>' 'M'N 'n' 'N' '<' 0x0303 '<' 'N'O 'o' 'O' '(' 0x00 '(' 'O'P 'p' 'P' ')' 0x00 ')' 'P'Q 'q' 'Q' '*' 0x0300 '*' 'Q'R 'r' 'R' '3' 0x20AC '3' 'R'S 's' 'S' '4' 0x00DF '4' 'S'T 't' 'T' '+' 0x00A3 '+' 'T'U 'u' 'U' '&' 0x0308 '&' 'U'V 'v' 'V' '9' '^' '9' 'V'W 'w' 'W' '1' 0x00 '1' 'W'X 'x' 'X' '7' 0xEF00 '7' 'X'Y 'y' 'Y' '!' 0x00A1 '!' 'Y'Z 'z' 'Z' '#' 0x00 '#' 'Z'COMMA ',' ';' ';' '|' ',' ','PERIOD '.' ':' ':' 0x2026 '.' '.'AT '@' '0' '0' 0x2022 '0' '@'SLASH '/' '?' '?' '/' '/' '/'SPACE 0x20 0x20 0x9 0x9 0x20 0x20NEWLINE 0xa 0xa 0xa 0xa 0xa 0xa# on pc keyboardsTAB 0x9 0x9 0x9 0x9 0x9 0x90 '0' ')' ')' ')' '0' '0'1 '1' '!' '!' '!' '1' '1'2 '2' '@' '@' '@' '2' '2'3 '3' '#' '#' '#' '3' '3'4 '4' '$' '$' '$' '4' '4'5 '5' '%' '%' '%' '5' '5'6 '6' '^' '^' '^' '6' '6'7 '7' '&' '&' '&' '7' '7'8 '8' '*' '*' '*' '8' '8'9 '9' '(' '(' '(' '9' '9'GRAVE '`' '~' '`' '~' '`' '`'MINUS '-' '_' '-' '_' '-' '-'EQUALS '=' '+' '=' '+' '=' '='LEFT_BRACKET '[' '{' '[' '{' '[' '['RIGHT_BRACKET ']' '}' ']' '}' ']' ']'BACKSLASH '/' '|' '/' '|' '/' '/'SEMICOLON ';' ':' ';' ':' ';' ';'APOSTROPHE ''' '"' ''' '"' ''' '''STAR '*' '*' '*' '*' '*' '*'POUND '#' '#' '#' '#' '#' '#'PLUS '+' '+' '+' '+' '+' '+' Resource Binary File Format
The file snippet above gets converted to the following by the makekcharmap tool as part of the build process. You can mmap this file in and share the approximately 4k of memory that it uses between processes to minimize load time.
| Offset | Size (bytes) | Description |
|---|---|---|
| 0x00-0x0b | The ascii value "keycharmap1" including the null character | |
| 0x0c-0x0f | padding | |
| 0x10-0x13 | The number of entries in the modifiers table (COLS) | |
| 0x14-0x17 | The number of entries in the characters table (ROWS) | |
| 0x18-0x1f | padding | |
| 4*COLS | Modifiers table. The modifier mask values that each of the columns in the characters table correspond to. | |
| padding to the next 16 byte boundary | ||
| 4*COLS*ROWS | Characters table. The modifier mask values that each of the columns correspond to. |
Implementing Your Own Driver (Driver Template)
The following file, pguide_events.c, illustrates how to implement an Android keymap driver.
/* * pguide_events.c * * ANDROID PORTING GUIDE: INPUT EVENTS DRIVER TEMPLATE * * This template is designed to an example of the functionality * necessary for Android to recieve input events. The PGUIDE_EVENT * macros are meant as pointers indicating where to implement the * hardware specific code necessary for the new device. The existence * of the macros is not meant to trivialize the work required, just as * an indication of where the work needs to be done. * * Copyright 2007, Google Inc. * Based on goldfish-events.c * */#include #include #include #include #include #include #include #include #include #define PGUIDE_EVENTS_INTERRUPT do{} while(0)#define PGUIDE_EVENTS_PROBE do{} while(0)struct event_dev { struct input_dev *input; int irq;};static irqreturn_t pguide_events_interrupt(int irq, void *dev_id){ struct event_dev *edev = dev_id; unsigned type=0, code=0, value=0; /* Set up type, code, and value per input.h */ PGUIDE_EVENTS_INTERRUPT; input_event(edev->input, type, code, value); return IRQ_HANDLED;}static int pguide_events_probe(struct platform_device *pdev){ struct input_dev *input_dev; struct event_dev *edev; printk("*** pguide events probe ***/n"); edev = kzalloc(sizeof(struct event_dev), GFP_KERNEL); input_dev = input_allocate_device(); /* Setup edev->irq and do any hardware init */ PGUIDE_EVENTS_PROBE; if(request_irq(edev->irq, pguide_events_interrupt, 0, "pguide_events", edev) < 0) { goto fail; } /* indicate that we generate key events */ set_bit(EV_KEY, input_dev->evbit); set_bit(EV_REL, input_dev->evbit); set_bit(EV_ABS, input_dev->evbit); /* indicate that we generate *any* key event */ bitmap_fill(input_dev->keybit, KEY_MAX); bitmap_fill(input_dev->relbit, REL_MAX); bitmap_fill(input_dev->absbit, ABS_MAX); platform_set_drvdata(pdev, edev); input_dev->name = "pguide_events"; input_dev->private = edev; input_dev->cdev.dev = &pdev->dev; input_register_device(input_dev); return 0;fail: kfree(edev); input_free_device(input_dev); return -EINVAL;}static struct platform_driver pguide_events_driver = { .probe = pguide_events_probe, .driver = { .name = "pguide_events", },};static int __devinit pguide_events_init(void){ return platform_driver_register(&pguide_events_driver);}static void __exit pguide_events_exit(void){}module_init(pguide_events_init);module_exit(pguide_events_exit);MODULE_DESCRIPTION("Pguide Event Device");MODULE_LICENSE("GPL"); Sample Implementation
Assume the following for the setup of a new keypad device:
android.keylayout.partnerxx_keypad = /system/usr/keylayout/partnerxx_keypad.klandroid.keychar.partnerxx_keypad = /system/usr/keychars/partnerxx.kcm The following example log file indicates that you have correctly registered the new keypad:
I/EventHub( 1548): New device: path=/dev/input/event0 name=partnerxx_keypad id=0x10000 (of 0x1) index=1 fd=30I/EventHub( 1548): new keyboard input device added, name = partnerxx_keypadD/WindowManager( 1548): Starting input thread.D/WindowManager( 1548): Startup complete!I/EventHub( 1548): New keyboard: name=partnerxx_keypad keymap=partnerxx_keypad.kl keymapPath=/system/usr/keychars/partnerxx_keypad.kcm.binI/ServiceManager( 1535): ServiceManager: addService(window, 0x13610)I/EventHub( 1548): Reporting device opened: id=0x10000, name=/dev/input/event0I/KeyInputQueue( 1548): Device added: id=0x10000, name=partnerxx_keypad, classes=1I/KeyInputQueue( 1548): Keymap: partnerxx_keypad.kl The snippet above contains artificial line breaks to maintain a print-friendly document.
转自android官网：http://source.android.com/porting/keymaps_keyboard_input.html
这篇文章不错，关于linux底层的键盘驱动：http://www.cnitblog.com/luofuchong/archive/2007/11/12/36157.html
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