淺析linux下鍵盤裝置工作和註冊流程

淺析linux下鍵盤裝置工作和註冊流程

【淺析linux下滑鼠驅動的實現】
 input_init()=>
=>
class_register(&input_class);註冊input類
input_proc_init();建立proc下的目錄和檔案
register_chrdev(INPUT_MAJOR, "input", &input_fops);註冊驅動程式到cdev_map上,以待驅動裝置.

drivers/input/keyboard/pxa3xx_keypad.c為我們的keyboard裝置,
pxa3xx_keypad_probe=>
request_irq(IRQ_ENHROT, &enhanced_rotary_interrupt,
            IRQF_DISABLED, "Enhanced Rotary", (void *)keypad);註冊快速鍵中斷
request_irq(IRQ_KEYPAD, pxa3xx_keypad_interrupt, IRQF_DISABLED,pdev->name, keypad);註冊中斷
static irqreturn_t pxa3xx_keypad_interrupt(int irq, void *dev_id)
{
    struct pxa3xx_keypad *keypad = dev_id;
    uint32_t kpc = keypad_readl(KPC);

    if (kpc & KPC_MI)
        pxa3xx_keypad_scan_matrix(keypad);

    if (kpc & KPC_DI)
        pxa3xx_keypad_scan_direct(keypad);

    return IRQ_HANDLED;
}
在irq中如果讀到了key,那麼會直接調用
input_report_key(keypad->input_dev,lookup_matrix_keycode(keypad, row, col),
                new_state[col] & (1 << row));
static inline unsigned int lookup_matrix_keycode(
        struct pxa3xx_keypad *keypad, int row, int col)
{
    return keypad->matrix_keycodes[(row << 3) + col];
}
input_report_key(struct input_dev *dev, unsigned int code, int value)
dev為input_dev裝置,我們的4*4鍵盤
code為標準PC鍵盤碼值
value為按鍵動作,為1表示鍵盤按下,為0表示按鍵抬起
static inline void input_report_key(struct input_dev *dev, unsigned int code, int value)
{
    input_event(dev, EV_KEY, code, !!value);
}
void input_event(struct input_dev *dev,
         unsigned int type, unsigned int code, int value)
{
    unsigned long flags;

    if (is_event_supported(type, dev->evbit, EV_MAX)) {
        spin_lock_irqsave(&dev->event_lock, flags);
        add_input_randomness(type, code, value);//因為按鍵的存在隨機性,所以按鍵是給系統提供墒隨機數的好來源.
        input_handle_event(dev, type, code, value);
        spin_unlock_irqrestore(&dev->event_lock, flags);
    }
}
static void input_handle_event(struct input_dev *dev,
                   unsigned int type, unsigned int code, int value)
{
    ...
        case EV_KEY:
        if (is_event_supported(code, dev->keybit, KEY_MAX) &&
            !!test_bit(code, dev->key) != value) {//這次來的是否為新的索引值

            if (value != 2) {
                __change_bit(code, dev->key);//通過異或^操作,反轉code對應的bitmap,如果value等於2,那麼將忽略該按鍵
                if (value)
                    input_start_autorepeat(dev, code);//鍵盤按下,那麼開啟定時檢測,這樣可以出現連續輸入的效果
            }

            disposition = INPUT_PASS_TO_HANDLERS;
        }
        break;
    ...
}
static void input_start_autorepeat(struct input_dev *dev, int code)
{
    if (test_bit(EV_REP, dev->evbit) &&
     dev->rep[REP_PERIOD] && dev->rep[REP_DELAY] &&
     dev->timer.data) {
        dev->repeat_key = code;
        mod_timer(&dev->timer,//重新啟動定時器input_repeat_key,時間間隔msecs_to_jiffies(dev->rep[REP_DELAY])
             jiffies + msecs_to_jiffies(dev->rep[REP_DELAY]));
    }
}

static void input_repeat_key(unsigned long data)
{
    struct input_dev *dev = (void *) data;
    unsigned long flags;

    spin_lock_irqsave(&dev->event_lock, flags);

    if (test_bit(dev->repeat_key, dev->key) &&
     is_event_supported(dev->repeat_key, dev->keybit, KEY_MAX)) {

        input_pass_event(dev, EV_KEY, dev->repeat_key, 2);//交給處理按鍵函數

        if (dev->sync) {
            /*
             * Only send SYN_REPORT if we are not in a middle
             * of driver parsing a new hardware packet.
             * Otherwise assume that the driver will send  ...
             * SYN_REPORT once it's done.
             */
            input_pass_event(dev, EV_SYN, SYN_REPORT, 1);
        }

        if (dev->rep[REP_PERIOD])
            mod_timer(&dev->timer, jiffies +
                    msecs_to_jiffies(dev->rep[REP_PERIOD]));
    }

    spin_unlock_irqrestore(&dev->event_lock, flags);
}

input_pass_event=>
handle->handler->event(handle, type, code, value);
就是kbd_handler的kbd_event=>kbd_keycode=>
atomic_notifier_call_chain(&keyboard_notifier_list, KBD_UNICODE, &param)
通知掛在keyboard鏈上所有等待鍵盤輸入的應用程式,
通過register_keyboard_notifier()函數可以註冊到鍵盤鏈上【gliethttp.Leith】,

input_dev = input_allocate_device();申請一個input裝置空間
input_dev->open = pxa3xx_keypad_open;給這個空間填充方法
input_dev->close = pxa3xx_keypad_close;
input_dev->private = keypad;
set_bit(EV_KEY, input_dev->evbit);//鍵按下
set_bit(EV_REL, input_dev->evbit);//鍵釋放
pxa3xx_keypad_build_keycode(keypad);//裝置鍵盤對應碼
該函數將根據pxa3xx_device_keypad裝置下的matrix_key_map進行鍵控設定,
pxa_set_keypad_info(&jades_keypad_info)=>將jades_keypad_info登記為pdata;
#define MAX_MATRIX_KEY_NUM (8 * 8)
matrix_keycodes[MAX_MATRIX_KEY_NUM];表示為8*8鍵盤
keypad->matrix_keycodes[(row << 3) + col] = code;表示第row行的第col列處按鍵,代表code編碼值,這個為我們內部使用.
set_bit(code, input_dev->keybit);//設定code為我們的鍵盤對作業系統可用的鍵盤值
if(pdata->direct_key_num) {
    for (i = 0; i < pdata->direct_key_num; i++) {
        set_bit(pdata->direct_key_map[i], input_dev->keybit);//快速鍵單元
    }
}
set_bit(KEY_POWER, input_dev->keybit);//登記電源按鍵為系統可見按鍵
input_register_device(input_dev);=>//註冊設該備devices_subsys匯流排上
int input_register_device(struct input_dev *dev)
{
    static atomic_t input_no = ATOMIC_INIT(0);
    struct input_handler *handler;
    const char *path;
    int error;

    __set_bit(EV_SYN, dev->evbit);

    /*
     * If delay and period are pre-set by the driver, then autorepeating
     * is handled by the driver itself and we don't do it in input.c.
     */

    init_timer(&dev->timer);
    if (!dev->rep[REP_DELAY] && !dev->rep[REP_PERIOD]) {
        dev->timer.data = (long) dev;
        dev->timer.function = input_repeat_key;//消抖處理函數,採用延時消抖
        dev->rep[REP_DELAY] = 500;//250;
        dev->rep[REP_PERIOD] = 66;//33;
    }

    if (!dev->getkeycode)
        dev->getkeycode = input_default_getkeycode;

    if (!dev->setkeycode)
        dev->setkeycode = input_default_setkeycode;
    //在/sys/class/input下建立以input0,input1為目錄名的input類型裝置
    snprintf(dev->dev.bus_id, sizeof(dev->dev.bus_id),
         "input%ld", (unsigned long) atomic_inc_return(&input_no) - 1);

    if (dev->cdev.dev)
        dev->dev.parent = dev->cdev.dev;

    error = device_add(&dev->dev);//將裝置登記到裝置匯流排上,之後將以目錄和檔案的形式呈現
    if (error)
        return error;

    path = kobject_get_path(&dev->dev.kobj, GFP_KERNEL);
    printk(KERN_INFO "input: %s as %s/n",
        dev->name ? dev->name : "Unspecified device", path ? path : "N/A");
    kfree(path);

    error = mutex_lock_interruptible(&input_mutex);
    if (error) {
        device_del(&dev->dev);
        return error;
    }

    list_add_tail(&dev->node, &input_dev_list);
//將裝置放到input的鏈表上,該鏈表上存放著所有input類型的dev裝置對象【gliethttp.Leith】
    list_for_each_entry(handler, &input_handler_list, node)
        input_attach_handler(dev, handler);
//從input_handler_list驅動鏈表上嘗試匹配,是否有驅動該dev裝置的driver驅動,如果有,那麼將匹配的驅動綁定給dev裝置,來驅動這個dev.
    input_wakeup_procfs_readers();

    mutex_unlock(&input_mutex);

    return 0;
}

drivers/char/keyboard.c
kbd_init()=>
input_register_handler(&kbd_handler); 註冊鍵盤驅動到input_handler_list鏈表上

static int input_attach_handler(struct input_dev *dev, struct input_handler *handler)
{
    const struct input_device_id *id;
    int error;
//看看這個咚咚,是不是在黑名單裡,如果在,那麼就byebye了【gliethttp.Leith】
    if (handler->blacklist && input_match_device(handler->blacklist, dev))
        return -ENODEV;

    id = input_match_device(handler->id_table, dev);
    if (!id)
        return -ENODEV;

    error = handler->connect(handler, dev, id);//ok,找到驅動該dev的driver,那麼嘗試串連
    if (error && error != -ENODEV)
        printk(KERN_ERR
            "input: failed to attach handler %s to device %s, "
            "error: %d/n",
            handler->name, kobject_name(&dev->dev.kobj), error);

    return error;
}

kbd_connect=>input_register_handle=>input_open_device=>pxa3xx_keypad_open配置鍵盤io口

 

本文來自CSDN部落格，轉載請標明出處：http://blog.csdn.net/zpf1217/archive/2009/10/16/4679731.aspx