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以下以内核自带的gpio_keys驱动为例,介绍输入子系统的使用.
主要的原因是gpio_keys驱动比较简单易懂,另外不是没个人都有触摸屏,但键盘的话相信每一块开发板上都配有.,先从下到上的分析底层驱动是如何提交输入事件的:
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drivers/input/keyboard/gpio_keys.c:

static int __devinit gpio_keys_probe(struct platform_device *pdev)
{
struct gpio_keys_platform_data *pdata = pdev->dev.platform_data;
struct input_dev *input;
int i, error;

input = input_allocate_device();//申请input_dev结构
if (!input)
return -ENOMEM;

platform_set_drvdata(pdev, input);//把input_dev结构放好(以后方便调用)

input->evbit[0] = BIT(EV_KEY);//目前event的类型不操作32,所以你会看到对于evbit数组的操作都是对evbit[0]中的位来进行操作.

input->name = pdev->name;
input->phys = "gpio-keys/input0";
input->dev.parent = &pdev->dev;

input->id.bustype = BUS_HOST;
input->id.vendor = 0x0001;
input->id.product = 0x0001;
input->id.version = 0x0100;

for (i = 0; i < pdata->nbuttons; i++) {
struct gpio_keys_button *button = &pdata->buttons[i];
int irq = gpio_to_irq(button->gpio);
unsigned int type = button->type : EV_KEY;

set_irq_type(irq, IRQ_TYPE_EDGE_BOTH);

/* 根据用户所指定的gpio_keys来申请中断和注册中断处理函数*/
error = request_irq(irq, gpio_keys_isr, IRQF_SAMPLE_RANDOM,
button->desc button->desc : "gpio_keys",
pdev);
if (error) {
printk(KERN_ERR "gpio-keys: unable to claim irq %d; error %d\n",
irq, error);
goto fail;
}

input_set_capability(input, type, button->code);
}

error = input_register_device(input);//注册输入设备,并和对应的handler处理函数挂钩
if (error) {
printk(KERN_ERR "Unable to register gpio-keys input device\n");
goto fail;
}

return 0;

fail:
for (i = i - 1; i >= 0; i--)
free_irq(gpio_to_irq(pdata->buttons[i].gpio), pdev);

input_free_device(input);

return error;
}