标签:关闭 rk3288 syn type i++ log schedule uil 按键
本文转载自:http://blog.csdn.net/kris_fei/article/details/77894406
Rockchip的按键驱动位于 kernel/drivers/input/keyboard/rk_keys.c
默认支持的keys在dts中定义:
其中power key作为普通gpio,具有唤醒功能。而其他按键比如,volume up/down 可以通过adc精确读取到gpio的电压值,原理图如下:
和一般的按键一样,驱动是通过内核input子系统来将keys注册供用户空间使用
static int keys_probe(struct platform_device *pdev)
{
input = devm_input_allocate_device(dev);
input->name = "rk29-keypad"; /* pdev->name; */
input->phys = "gpio-keys/input0";
input->dev.parent = dev;
input->id.bustype = BUS_HOST;
input->id.vendor = 0x0001;
input->id.product = 0x0001;
input->id.version = 0x0100;
error = input_register_device(input);
}
dts keys的解析通过rk_keys_parse_dt()实现。而每个key都会注册一个定时器函数来处理状态变化并通知用户空间。
for (i = 0; i < ddata->nbuttons; i++) {
if (button->code) {
setup_timer(&button->timer,
keys_timer, (unsigned long)button);
}
}
keys_timer():
static void keys_timer(unsigned long _data)
{
//普通gpio直接读取
if (button->type == TYPE_GPIO)
state = !!((gpio_get_value(button->gpio) ? 1 : 0) ^
button->active_low);
else
//adc转成bool状态值
state = !!button->adc_state;
//状态变化上报事件
if (button->state != state) {
button->state = state;
input_event(input, EV_KEY, button->code, button->state);
input_event(input, EV_KEY, button->code, button->state);
input_sync(input);
}
//10ms后启动定时器
if (state)
mod_timer(&button->timer, jiffies + DEBOUNCE_JIFFIES);
}
定时器会处理普通gpio和adc两种类型的按键,当状态变化时,会向用户空间上报当前事件、键值、状态。默认开机时,定时器处理函数因为检测不到状态变化而关闭退出。
定时器的开启有两个地方会被调用:
1.系统开机会启一个工作队列,每100ms周期性调用一次检测有没有按键触发
static void adc_key_poll(struct work_struct *work)
{
if (!ddata->in_suspend) {
//读取adc电压
result = rk_key_adc_iio_read(ddata);
for (i = 0; i < ddata->nbuttons; i++) {
//允许值有一定范围的漂移
if (result < button->adc_value + DRIFT_ADVALUE &&
result > button->adc_value - DRIFT_ADVALUE)
button->adc_state = 1;
else
button->adc_state = 0;
if (button->state != button->adc_state)
mod_timer(&button->timer,
jiffies + DEBOUNCE_JIFFIES);
}
}
//周期性调用。ADC_SAMPLE_JIFFIES为100ms
schedule_delayed_work(&ddata->adc_poll_work, ADC_SAMPLE_JIFFIES);
}
2. power key唤醒时中断处理会被触发
static irqreturn_t keys_isr(int irq, void *dev_id)
{
//上报power key事件
if (button->wakeup && pdata->in_suspend) {
button->state = 1;
input_event(input, EV_KEY, button->code, button->state);
input_sync(input);
}
if (button->wakeup)
wake_lock_timeout(&pdata->wake_lock, WAKE_LOCK_JIFFIES);
mod_timer(&button->timer, jiffies + DEBOUNCE_JIFFIES);
return IRQ_HANDLED;
}
[RK3288][Android6.0] 系统按键驱动流程分析【转】
标签:关闭 rk3288 syn type i++ log schedule uil 按键
原文地址:http://www.cnblogs.com/zzb-Dream-90Time/p/7778878.html