1、简介
Linux输入子系统是内核中很常用的系统,内核里面已经包含了一些鼠标、键盘、按键、触摸屏等一系列驱动代码,本章我们分析一下内核中gpio_keys的代码流程。
2、流程图
3、代码分析
代码的主要做的事情就是初始化input driver,初始化按键,按键中断后以某种形式(work、timer,以上流程图只分析了work,timer类似)上报event。
3.1、input参数配置
input->name = pdata->name ? : pdev->name;
input->phys = "gpio-keys/input0";
input->dev.parent = dev;
input->open = gpio_keys_open;
input->close = gpio_keys_close;
input->id.bustype = BUS_HOST;
input->id.vendor = 0x0001;
input->id.product = 0x0001;
input->id.version = 0x0100;
input->keycode = ddata->keymap;
input->keycodesize = sizeof(ddata->keymap[0]);
input->keycodemax = pdata->nbuttons;
3.2、获取按键信息
static int gpio_keys_setup_key(struct platform_device *pdev,
struct input_dev *input,
struct gpio_keys_drvdata *ddata,
const struct gpio_keys_button *button,
int idx,
struct fwnode_handle *child)
{
const char *desc = button->desc ? button->desc : "gpio_keys";
struct device *dev = &pdev->dev;
struct gpio_button_data *bdata = &ddata->data[idx];
irq_handler_t isr;
unsigned long irqflags;
int irq;
int error;
bdata->input = input;
bdata->button = button;
spin_lock_init(&bdata->lock);
if (child) {
bdata->gpiod = devm_fwnode_get_gpiod_from_child(dev, NULL,
child,
GPIOD_IN,
desc)