最后,我挖得太深了。代码示例就在我的眼皮底下。我需要的一切都在 BD-SL devkit 的板特定代码中(可以在 BD-SL 源代码树中找到mydroid/BD-SL-i.MX6/kernel_imx/arch/arm/mach-mx6/board-mx6_nitrogen6x.c
)
此代码特定于飞思卡尔 i.MX6 提供的内核,但不同部分应该很容易移植/适应其他 Android 嵌入式平台。
GPIO 定义。为简单起见,我跳过了 GPIO 引脚多路复用器。该引脚需要多路复用到 GPIO 功能:
#define GP_ONOFF_KEY IMX_GPIO_NR(2, 3)
输入键的定义
#define GPIO_BUTTON(gpio_num, ev_code, act_low, descr, wake) \
{ \
.gpio = gpio_num, \
.type = EV_KEY, \
.code = ev_code, \
.active_low = act_low, \
.desc = "btn " descr, \
.wakeup = wake, \
}
static struct gpio_keys_button buttons[] = {
GPIO_BUTTON(GP_ONOFF_KEY, KEY_POWER, 1, "key-power", 1),
};
对应平台数据和平台设备的定义:
static struct gpio_keys_platform_data button_data = {
.buttons = buttons,
.nbuttons = ARRAY_SIZE(buttons),
};
static struct platform_device button_device = {
.name = "gpio-keys",
.id = -1,
.num_resources = 0,
.dev = {
.platform_data = &button_data,
}
};
平台设备注册
static void __init add_device_buttons(void)
{
platform_device_register(&button_device);
}
/*!
* Board specific initialization.
*/
static void __init board_init(void)
{
//...
add_device_buttons();
//...
}
为了完整起见,指向 Board 特定初始化的初始化数据结构
/*
* initialize data structure.
*/
MACHINE_START(MX6_NITROGEN6X, "Boundary Devices Nitrogen6X/SABRE Lite Board")
/* Maintainer: Boundary Devices */
.boot_params = MX6_PHYS_OFFSET + 0x100,
.fixup = fixup_mxc_board,
.map_io = mx6_map_io,
.init_irq = mx6_init_irq,
.init_machine = board_init,
.timer = &timer,
.reserve = reserve,
MACHINE_END