基于BarrierBreaker版本,基于AR9331 AP121 Demo单板 来进行描述
1.灯
A.在mach-ap121.c中,定义了灯所对应的GPIO定义:
#define AP121_GPIO_LED_WLAN 0
#define AP121_GPIO_LED_USB 1
并定义了灯的GPIO结构对象:
static struct gpio_led ap121_leds_gpio[] __initdata = { { .name = "ap121:green:usb", .gpio = AP121_GPIO_LED_USB, .active_low = 0, }, { .name = "ap121:green:wlan", .gpio = AP121_GPIO_LED_WLAN, .active_low = 0, }, }
在初始化函数:ap121_setup 中,利用ath79_register_leds_gpio(-1, ARRAY_SIZE(ap121_leds_gpio), ap121_leds_gpio);实现了LED device的注册。此函数调用后,会创建platform类型的设备,并和leds-gpio驱动(leds-gpio.c)实现了绑定。这样,就会在/sys/devices/platform/leds-gpio/目录中,产生对应的led灯的控制目录:
则通过 echo 1 > brightness,就可以控制灯亮; echo 0 > brightness,就可以控制灯灭 。
2.按键
A.在mach-ap121.c中,定义了按键对应的GPIO以及数据结构对象:
#define AP121_GPIO_BTN_JUMPSTART 11
#define AP121_GPIO_BTN_RESET 12
以及
static struct gpio_keys_button ap121_gpio_keys[] __initdata = { { .desc = "jumpstart button", .type = EV_KEY, .code = KEY_WPS_BUTTON, //定义在gpio-button-hotplug.c .debounce_interval = AP121_KEYS_DEBOUNCE_INTERVAL, .gpio = AP121_GPIO_BTN_JUMPSTART, .active_low = 1, }, { .desc = "reset button", .type = EV_KEY, .code = KEY_RESTART, //定义在gpio-button-hotplug.c .debounce_interval = AP121_KEYS_DEBOUNCE_INTERVAL, .gpio = AP121_GPIO_BTN_RESET, .active_low = 1, }, }
在初始化函数:ap121_setup 中,利用
ath79_register_gpio_keys_polled(-1, AP121_KEYS_POLL_INTERVAL,ARRAY_SIZE(ap121_gpio_keys),ap121_gpio_keys);
实现了KEY device的注册。此函数调用后,会创建platform类型的设备,并和gpio-keys-polled驱动(gpio-button-hotplug.c
)实现了绑定。
B. 当按键时,则触发button_hotplug_event函数(gpio-button-hotplug.c):调用button_hotplug_create_event产生uevent事件,调用button_hotplug_fill_even填充事件(JSON格式),并最终调用button_hotplug_work发出uevent广播
[ "if", [ "and", [ "has", "BUTTON" ], [ "eq", "SUBSYSTEM", "button" ], ], [ "exec", "/etc/rc.button/%BUTTON%" ] ],
[ "if", [ "eq", "SUBSYSTEM", [ "net", "input", "usb", "ieee1394", "block", "atm", "zaptel", "tty", "button" ] ], [ "exec", "/sbin/hotplug-call", "%SUBSYSTEM%" ] ],
在openwrt的GPIO系统上,主要使用了如下技术点:
driver-device-platform, uevent,procd,JSON,UCI;当然还需要读懂对应芯片的Datasheet
注:博主有很多openwrt应用文档,推荐学习。