kernel（十）按键
一、定义keys平台设备
参考： Documentation/devicetree/bindings/gpio/gpio_keys.txt
drivers/input/keyboard/gpio_keys.c 查看 TQ210 原理图
1.1、在 mach-Louis210.c 中添加头文件
1.2、定义 keys 的平台设备
/* gpio keys (add by JerryGou) */
static struct gpio_keys_button buttons[] = {
[0] = {
.code = KEY_UP, 按键对应的键码
.gpio = S5PV210_GPH0(0), 按键对应的IO口
.active_low = 1, 通过查看驱动代码，可得知表示是否按键按下是低电平，如是则设１
.desc = "KEY_UP", 申请io口，申请中断时使用的名字
.type = EV_KEY, 输入设备的事件类型，按键用EV_KEY
.debounce_interval = 50, 防抖动用，间隔多久时间
},
[1] = {
.code = KEY_DOWN,
.gpio = S5PV210_GPH0(1),
.active_low = 1,
.desc = "KEY_DOWN",
.type = EV_KEY,
.debounce_interval = 50,
},
[2] = {
.code = KEY_LEFT,
.gpio = S5PV210_GPH0(2),
.active_low = 1,
.desc = "KEY_LEFT",
.type = EV_KEY,
.debounce_interval = 50,
},
[3] = {
.code = KEY_RIGHT,
.gpio = S5PV210_GPH0(3),
.active_low = 1,
.desc = "KEY_RIGHT",
.type = EV_KEY,
.debounce_interval = 50,
},
[4] = {
.code = KEY_ENTER,
.gpio = S5PV210_GPH0(4),
.active_low = 1,
.desc = "KEY_ENTER",
.type = EV_KEY,
.debounce_interval = 50,
},
[5] = {
.code = KEY_BACK,
.gpio = S5PV210_GPH0(5),
.active_low = 1,
.desc = "KEY_BACK",
.type = EV_KEY,
.debounce_interval = 50,
},
[6] = {
.code = KEY_MENU,
.gpio = S5PV210_GPH2(6),
.active_low = 1,
.desc = "KEY_MENU",
.type = EV_KEY,
.debounce_interval = 50,
},
[7] = {
.code = KEY_POWER,
.gpio = S5PV210_GPH2(7),
.active_low = 1,
.desc = "KEY_POWER",
.type = EV_KEY,
.debounce_interval = 50,
},
};
static struct gpio_keys_platform_data Louis210_keys_pdata = {
.buttons = buttons,
.nbuttons = ARRAY_SIZE(buttons),
.rep = 1,
};
static struct platform_device Louis210_keys = {
.name = "gpio-keys",
.dev = {
.platform_data = &Louis210_keys_pdata,
},
.id = -1,
};
二、配置内核Device Drivers ---> 编译后/sys/bus/platform/drivers/目录下应有”gpio-keys”目录 |
要让按键支持控制台，需要配置/etc/inittab，在开一个 tty
tty2::askfirst:-/bin/sh
编译内核，运行测试
成功注册 gpio_keys，设备文件为/dev/input/event1
现在按 Enter 键（key5）， LCD 效果如下
三、用户空间程序测试
key_app_test.c
#include
#include
#include
#include
#include
#include
#include
int fd = -1;
struct input_event ev;
void sig_handle(int sig)
{
int rc = -1;
rc = read(fd, &ev, sizeof(struct input_event));
if (rc < 0)
{
perror("read");
return;
}
if (EV_KEY == ev.type)
{
if (1 == ev.value)
printf("key %d, value:%d\n", ev.code, ev.value);
else
printf("key %d, value:%d\n", ev.code, ev.value);
}
}
int main(int argc, char *argv[])
{
size_t rb;
int version;
char name[20];
int oflags = 0;
if (argc != 2)
{
fprintf(stderr, "Usage:%s /dev/eventx\n", argv[0]);
exit(1);
}
if ((fd = open(argv[1], O_RDONLY)) < 0)
{
perror("open error");
exit(1);
}
#if 0
if (ioctl(fd, EVIOCGNAME(sizeof(name)-1), name) < 0)
{
perror("getname error");
exit(1);
}
printf("name=%s\n", name);
if (ioctl(fd, EVIOCGVERSION, &version) < 0)
{
perror("getversion error");
exit(1);
}
printf("version=0x%x\n", version);
while(1)
{
rb = read(fd, &ev, sizeof(struct input_event));
if (rb < (int)sizeof(struct input_event))
{
perror("read error");
exit(1);
}
if (EV_KEY == ev.type)
{
if (1 == ev.value)
printf("key %d is pressed\n", ev.code);
else
printf("key %d is releassed\n", ev.code);
}
}
#else
signal(SIGIO, sig_handle);
fcntl(fd, F_SETOWN, getpid());
oflags = fcntl(fd, F_GETFL);
fcntl(fd, F_SETFL, oflags | FASYNC);
while (1)
sleep(1);
#endif
close(fd);
return 0;
}
测试效果：
四、keys 结构体分析
"include/linux/gpio_keys.h"
每个struct gpio_key_button的对象表示一个按键的具体信息
struct gpio_keys_button {
此按键对应的键码
unsigned int code; /* input event code (KEY_*, SW_*) */
此按键对应的一个io口
int gpio; /* -1 if this key does not support gpio */
通过查看驱动代码，可得知表示是否按键按下是低电平，如是则设１.
int active_low;
就是申请io口，申请中断时使用的名字
const char *desc;
输入设备的事件类型，按键用EV_KEY
unsigned int type; /* input event type (EV_KEY, EV_SW, EV_ABS) */
表示按键按下时是否唤醒系统, 这个需要io口硬件上有这功能
int wakeup; /* configure the button as a wake-up source */
防抖动用，间隔多久时间
int debounce_interval; /* debounce ticks interval in msecs */
...
};
gpio_keys_paltform_data对象表示一个输入设备, 一个输入设备可有多个按键
struct gpio_keys_platform_data {
多个按键需要用gpio_keys_button的变量数组才可以， buttons成员用于装数组首地址
struct gpio_keys_button *buttons;
在按键数组里的元素个数
int nbuttons;
轮询的按键的平台驱动所用
unsigned int poll_interval; /* polling interval in msecs - for polling driver only */
键按住时，是否重复提交按键
unsigned int rep:1; /* enable input subsystem auto repeat */
设备这边需在使用前所做的初始化工作，由设备驱动调用. 在输入设备产生的设备文件打开时触发调用
int (*enable)(struct device *dev);
设备这边需在结束工作前所做的工作, 由设备驱动调用.在输入设备产生的设备文件关闭时触发调用
void (*disable)(struct device *dev);
const char *name; /* input device name */
};
按键驱动示例：
现用一个按键连接再板上，SIG脚接到PA20. 当键按下时，SIG脚为高电平。键松开时，SIG脚为低电平.
mypdev.c
#include
#include
#include
#include
#include
#include
struct gpio_keys_button btns[] = {
{KEY_L, GPIOA(20), 0, "mygpio-keys", EV_KEY, 0, 100},
};
struct gpio_keys_platform_data pdata = {
.buttons = btns,
.nbuttons = ARRAY_SIZE(btns),
.rep = 1,
.name = "mygpio-keys",
};
struct platform_device mypdev = {
.name = "gpio-keys", 与平台驱动的名字一致才会匹配上
.id = -1,
.dev = {
.platform_data = &pdata,
},
};
module_driver(mypdev, platform_device_register, platform_device_unregister);
MODULE_LICENSE("GPL"); 五、keys 平台驱动分析
驱动源码在”drivers/input/keyboard/gpio_keys.c”, 里面是一个平台驱动，我们只要写平台设备描述硬件的资源与此驱动匹配即可。
static struct platform_driver gpio_keys_device_driver = {
.probe = gpio_keys_probe,
.remove = gpio_keys_remove,
.driver = {
.name = "gpio-keys", 可匹配名为"gpio-keys"的平台设备
.owner = THIS_MODULE,
.pm = &gpio_keys_pm_ops,
.of_match_table = of_match_ptr(gpio_keys_of_match), 按这个成员来匹配平台设备也是可以的，要求设备的名字为"gpio-keys"
}
};
通过阅读平台驱动的probe函数，可得知我们写的平台设备应提供具本哪些硬件信息.
static int __devinit gpio_keys_probe(struct platform_device *pdev)
{
这里可得知我们写的平台设备的platform_data成员应当提供gpio_keys_platform_data类型数据
const struct gpio_keys_platform_data *pdata = pdev->dev.platform_data;
在设备驱动里对每个匹配上的设备都准备一个独立的数据
struct gpio_keys_drvdata *ddata;
struct device *dev = &pdev->dev;
struct gpio_keys_platform_data alt_pdata;
struct input_dev *input;
int i, error;
int wakeup = 0;
...
对gpio_keys_drvdata对象的初始化
输入设备对象的初始化
...
}