常见的输入设备有键盘、鼠标、遥控杆、书写板、触摸屏等等,用户通过这些输入设备与Linux系统进行数据交换。
// include/linux/input.h struct input_dev { const char *name; //设备名称 const char *phys; //设备物理路径 const char *uniq; //设备唯一标识码 struct input_id id; unsigned long propbit[BITS_TO_LONGS(INPUT_PROP_CNT)]; unsigned long evbit[BITS_TO_LONGS(EV_CNT)]; //支持什么类型的输入事件 unsigned long keybit[BITS_TO_LONGS(KEY_CNT)]; //支持按键输入事件的话,支持哪些按键(键盘) unsigned long relbit[BITS_TO_LONGS(REL_CNT)]; //支持相对位移事件的话,支持哪些 unsigned long absbit[BITS_TO_LONGS(ABS_CNT)]; unsigned long mscbit[BITS_TO_LONGS(MSC_CNT)]; unsigned long ledbit[BITS_TO_LONGS(LED_CNT)]; unsigned long sndbit[BITS_TO_LONGS(SND_CNT)]; unsigned long ffbit[BITS_TO_LONGS(FF_CNT)]; unsigned long swbit[BITS_TO_LONGS(SW_CNT)]; ....... };
查看所有的输入设备:
ls /dev/input/* -l
查看输入设备的信息:
cat /proc/bus/input/devices
得到如下信息:
[root@imx6ull:~]# cat /proc/bus/input/devices I: Bus=0019 Vendor=0000 Product=0000 Version=0000 N: Name="20cc000.snvs:snvs-powerkey" P: Phys=snvs-pwrkey/input0 S: Sysfs=/devices/soc0/soc/2000000.aips-bus/20cc000.snvs/20cc000.snvs:snvs-powerkey/input/input0 U: Uniq= H: Handlers=kbd event0 evbug B: PROP=0 B: EV=3 B: KEY=100000 0 0 0 I: Bus=0018 Vendor=dead Product=beef Version=28bb //设备ID(定义在input.h的struct input_id结构体) N: Name="goodix-ts" //名称 P: Phys=input/ts //物理地址 S: Sysfs=/devices/virtual/input/input1 //sys系统地址 U: Uniq= //标识号(无) H: Handlers=event1 evbug B: PROP=2 //设备属性 B: EV=b //支持何种输入事件 B: KEY=1c00 0 0 0 0 0 0 0 0 0 0 //设备具有的键 B: ABS=6e18000 0 I: Bus=0019 Vendor=0001 Product=0001 Version=0100 N: Name="gpio-keys" P: Phys=gpio-keys/input0 S: Sysfs=/devices/soc0/gpio-keys/input/input2 U: Uniq= H: Handlers=kbd event2 evbug B: PROP=0 B: EV=3 B: KEY=c
// include/linux/input.h struct input_value { __u16 type; //当前数据的事件类型 __u16 code; //当前事件类型下的哪一个事件 __s32 value; // };
Type的内容:
// include/uapi/linux/input-event-codes.h /* * Event types */ #define EV_SYN 0x00 //同步事件 #define EV_KEY 0x01 //键盘事件 #define EV_REL 0x02 //相对位移事件 #define EV_ABS 0x03 //绝对位移事件 #define EV_MSC 0x04 #define EV_SW 0x05 #define EV_LED 0x11 #define EV_SND 0x12 #define EV_REP 0x14 #define EV_FF 0x15 #define EV_PWR 0x16 #define EV_FF_STATUS 0x17 #define EV_MAX 0x1f #define EV_CNT (EV_MAX+1)
code的内容(以EV_KEY举例)
// include/uapi/linux/input-event-codes.h #define KEY_RESERVED 0 #define KEY_ESC 1 #define KEY_1 2 #define KEY_2 3 #define KEY_3 4 #define KEY_4 5 #define KEY_5 6 #define KEY_6 7 #define KEY_7 8 #define KEY_8 9 #define KEY_9 10 #define KEY_0 11
request | 说明 |
---|---|
EVIOCGID | 返回输入设备ID |
EVIOCGBIT(ev,len) | 获取输入设备支持的事件类型列表 |
ev值的说明:ev参数表示要获取的事件类型,它是一个整数值
EVIOCGBIT的iotcl调用说明:必须使用
len = ioctl(fd, EVIOCGBIT(0, sizeof(evbit)), evbit); //len是evbit的实际读取大小,如果单独使用sizeof(evbit)得到len,将发生段错误
#include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <stdio.h> #include <sys/ioctl.h> #include <linux/input.h> /* 用法:./get_input_info /dev/input/event0 */ int main(int argc, char const **argv) { int fd; struct input_id id; int err; unsigned char byte; unsigned int evbit[2]; int i; int bit; unsigned int len; char *ev_names[] = { "EV_SYN ", "EV_KEY ", "EV_REL ", "EV_ABS ", "EV_MSC ", "EV_SW ", "NULL ", "NULL ", "NULL ", "NULL ", "NULL ", "NULL ", "NULL ", "NULL ", "NULL ", "NULL ", "NULL ", "EV_LED ", "EV_SND ", "NULL ", "EV_REP ", "EV_FF ", "EV_PWR ", }; if(argc != 2) { printf("Usage: %s <dev>\n", argv[0]); return -1; } fd = open(argv[1], O_RDWR); if(fd == -1) { printf("can not open %s\n", argv[1]); return -1; } err = ioctl(fd, EVIOCGID, &id); //返回输入设备ID if(err == 0) { printf("bustype = 0x%x\n", id.bustype ); printf("vendor = 0x%x\n", id.vendor ); printf("product = 0x%x\n", id.product ); printf("version = 0x%x\n", id.version ); } len = ioctl(fd, EVIOCGBIT(0,sizeof(evbit)), evbit); //返回输入事件类型 printf("support ev type:\n"); for(i = 0;i < len;i++) { byte = ((unsigned char *)evbit)[i]; for(bit = 0;bit < 8;bit++) { if(byte & (1<<bit)) { printf("%s \n", ev_names[i*8 + bit]); } } } return 0; }
[root@imx6ull:/mnt]# ./get_input_info /dev/input/event0 bustype = 0x19 vendor = 0x0 product = 0x0 version = 0x0 support ev type: EV_SYN EV_KEY [root@imx6ull:/mnt]# ./get_input_info /dev/input/event1 bustype = 0x18 vendor = 0xdead product = 0xbeef version = 0x28bb support ev type: EV_SYN EV_KEY EV_ABS
[root@imx6ull:~]# cat /proc/bus/input/devices I: Bus=0019 Vendor=0000 Product=0000 Version=0000 N: Name="20cc000.snvs:snvs-powerkey" P: Phys=snvs-pwrkey/input0 S: Sysfs=/devices/soc0/soc/2000000.aips-bus/20cc000.snvs/20cc000.snvs:snvs-powerkey/input/input0 U: Uniq= H: Handlers=kbd event0 evbug B: PROP=0 B: EV=3 B: KEY=100000 0 0 0 I: Bus=0018 Vendor=dead Product=beef Version=28bb N: Name="goodix-ts" P: Phys=input/ts S: Sysfs=/devices/virtual/input/input1 U: Uniq= H: Handlers=event1 evbug B: PROP=2 B: EV=b B: KEY=1c00 0 0 0 0 0 0 0 0 0 0 B: ABS=6e18000 0 I: Bus=0019 Vendor=0001 Product=0001 Version=0100 N: Name="gpio-keys" P: Phys=gpio-keys/input0 S: Sysfs=/devices/soc0/gpio-keys/input/input2 U: Uniq= H: Handlers=kbd event2 evbug B: PROP=0 B: EV=3 B: KEY=c
结论:EV值与程序输出的type结果一致
所谓的阻塞与非阻塞,是在open处声明。当设置为阻塞方式,如果没有输入事件,整个进程都在阻塞态
#include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <stdio.h> #include <sys/ioctl.h> #include <linux/input.h> #include <unistd.h> #include <string.h> /* 用法:./get_input_info /dev/input/event0 */ int main(int argc, char const **argv) { int fd; unsigned int len; struct input_event event; //read读到的是input_event类型的结构体 if(argc < 2) { printf("Usage: %s <dev> [noblock]\n", argv[0]); return -1; } if(argc == 3 && !strcmp(argv[2], "noblock")) { fd = open(argv[1], O_RDWR | O_NONBLOCK); //非阻塞(查询) } else { fd = open(argv[1], O_RDWR); } if(fd == -1) { printf("can not open %s\n", argv[1]); return -1; } while(1) { len = read(fd, &event, sizeof(event)); //阻塞方式下,进程阻塞在此 if(len == sizeof(event)) { printf("type = 0x%x, code = 0x%x, value = 0x%x", event.type, event.code, event.value); } else { printf("read err %d", len); } } return 0; }
poll会在设定的时间内进行监听,当改时间内有输入事件返回或超过设定时间没有事件返回,poll都将唤醒。poll/select函数可以监测多个文件,可以监测多种事件。
#include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <stdio.h> #include <sys/ioctl.h> #include <linux/input.h> #include <unistd.h> #include <string.h> #include <poll.h> /* 用法:./get_input_info /dev/input/event0 */ int main(int argc, char const **argv) { int fd; struct input_event event; //read读到的是input_event类型的结构体 struct pollfd pollfd; nfds_t nfds = 1; //同时打开一个文件 if(argc != 2) { printf("Usage: %s <dev>\n", argv[0]); return -1; } fd = open(argv[1], O_RDWR | O_NONBLOCK); //非阻塞(查询) if(fd == -1) { printf("can not open %s\n", argv[1]); return -1; } while(1) { pollfd.fd = fd; pollfd.events = POLLIN; pollfd.revents = 0; //revents初始化为0,当有输入事件传入,内核改写revents poll(&pollfd, nfds, 3000); //poll等待时间为3s if(pollfd.revents == POLLIN) //只有poll函数返回了数据,才调用read { while(read(fd, &event, sizeof(event)) == sizeof(event)) //把一次获取到的数据读完再退出 { printf("type = 0x%x, code = 0x%x, value = 0x%x\n", event.type, event.code, event.value); } } else if(pollfd.revents == 0) { printf("time out\n"); } else { printf("read err\n"); } } return 0; }
struct pollfd pollfd[n]; //n为文件个数 nfds_t nfds = n; //同时打开n个文件 ....... if(pollfd[0].revents == POLLIN){} //依次访问revents if(pollfd[1].revents == POLLIN){} .......
[补充]fcntl的五个功能:
#include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <stdio.h> #include <sys/ioctl.h> #include <linux/input.h> #include <unistd.h> #include <string.h> #include <signal.h> int fd; void sig_func(int sig) { struct input_event event; while(read(fd, &event, sizeof(event)) == sizeof(event)) { printf("type = 0x%x, code = 0x%x, value = 0x%x\n", event.type, event.code, event.value); } } /* 用法:./get_input_info /dev/input/event0 */ int main(int argc, char const **argv) { int count = 0; unsigned short flag; if(argc != 2) { printf("Usage: %s <dev>\n", argv[0]); return -1; } signal(SIGIO, sig_func); //1.注册信号处理函数(信号类型为IO类型) fd = open(argv[1], O_RDWR | O_NONBLOCK); //2.打开驱动(一定要用非阻塞方式,否则无输入事件进程一直被阻塞) if(fd == -1) { printf("can not open %s\n", argv[1]); return -1; } fcntl(fd ,F_SETOWN, getpid()); //3.告知驱动程序app进程ID flag = fcntl(fd, F_GETFL); //4.获得文件状态标记 fcntl(fd, F_SETFL, flag | FASYNC); //5.设置文件状态标记(将进程添加到驱动fasync事件等待队列) while(1) { printf("count = %d\n", count++); sleep(2); } return 0; }
[root@imx6ull:/mnt]# ./get_input_info /dev/input/event1 count = 0 count = 1 count = 2 //无输入事件时正常计数 type = 0x3, code = 0x39, value = 0x6 type = 0x3, code = 0x35, value = 0x1a6 type = 0x3, code = 0x36, value = 0x131 type = 0x3, code = 0x30, value = 0x1f type = 0x3, code = 0x3a, value = 0x1f type = 0x1, code = 0x14a, value = 0x1 type = 0x0, code = 0x0, value = 0x0 count = 3 type = 0x3, code = 0x35, value = 0x1a7 type = 0x0, code = 0x0, value = 0x0 count = 4 type = 0x3, code = 0x35, value = 0x1a9 type = 0x0, code = 0x0, value = 0x0 count = 5 type = 0x3, code = 0x35, value = 0x1a8 type = 0x0, code = 0x0, value = 0x0 count = 6