lv15 input子系统框架、外设驱动开发 5

一、input子系统基本框架

在我们日常的Linux系统中，存在大量的输入设备，例如按键、鼠标、键盘、触摸屏、摇杆等，他们本身就是字符设备，linux内核将这些字符设备的共同性抽象出来，简化驱动开发建立了一个input子系统。

Linux内核为了两个目的：

简化纯输入类外设（如：键盘、鼠标、游戏杆、轨迹球、触摸屏。。。等等）的驱动开发
统一输入类外设产生的数据格式（struct input_event），更加方便应用层编程

设计了输入子系统框架

Linux 内核驱动可以都是遵循一个逐层抽象的架构：最上层的抽象层便于系统软件的访问，中间层的实现硬件协议细节，同时提供上下两层连接的接口，对于最下层的 driver 来说就是要定义底层驱动要实现的接口和实际的设备控制，由于 Linux 内核各类驱动的框架支持，driver 可以更加关注设备本身的特性。
Linux输入子系统（linux input subsystem）也不例外，从上到下可以分为三层实现，分别为：输入子系统事件处理层（EventHandler）、输入子系统核心层（InputCore）和输入子系统设备驱动层。

事件处理层：接收来自核心层上报的事件，并选择对应的handler（事件处理器 struct input_handler）去处理。内核维护着多个事件处理器对象，每个input_handler对象专门处理一类事件，所有产生同类事件的设备驱动共用同一个handler。

设备驱动层：主要实现获取硬件设备的数据信息（包括触摸屏被按下、按下位置、鼠标移动、键盘按下等等），并转换为核心层定义的规范事件后提交给核心层，该层每个设备对应一个struct input_dev对象，

核心层：负责连接设备驱动层和事件处理层，为设备驱动层提供输入设备驱动的接口（struct input_dev）以及输入设备驱动的注册函数（input_register_device）,为事件处理层提供输入事件驱动的接口；通知事件处理层对事件进行处理。

二、驱动开发步骤

/*init或probe函数中：
1. 创建struct input_dev对象input_allocate_device
2. 设置事件类型以及相关参数set_bit
3. 注册struct input_dev对象input_register_device
*/

/*exit或remove函数中：
1. 注销struct input_dev对象input_unregister_device
2. 销毁struct input_dev对象input_free_device
*/

/*上报事件两种事件上报方式：1. 对有中断支持的输入设备：在其中断处理函数（上半部或下半部）中上报事件2. 对无中断支持的输入设备：使用workqueue循环定时上报(struct delayed_work)主要函数：input_event       //通用上报，上报的是分量，如x轴分量input_report_abs  //上报绝对坐标input_sync        //完整数据检查统一上报在这边处理，如x、y、z轴数据统一上报
*/

三、key2-input版代码解析

借用直接按键驱动的代码，按键中所有根字符设备相关的input子系统已经帮我们实现好了，都可以不需要。

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/gpio.h>
#include <linux/interrupt.h>
#include <linux/of_gpio.h>
#include <linux/of_irq.h>
#include <linux/cdev.h>
#include <linux/wait.h>
#include <linux/sched.h>
#include <linux/poll.h>
#include <linux/mm.h>
#include <linux/input.h>   //<------------
#include <linux/delay.h>
#include <linux/slab.h>
#include <asm/uaccess.h>struct fs4412key2_dev
{struct input_dev *pdev;int gpio;int irqno;
};struct fs4412key2_dev *pgmydev = NULL;irqreturn_t key2_irq_handle(int no,void *arg)  
{struct fs4412key2_dev *pmydev = (struct fs4412key2_dev *)arg;int status1 = 0;int status2 = 0;status1 = gpio_get_value(pmydev->gpio);mdelay(1);status2 = gpio_get_value(pmydev->gpio);if(status1 != status2){return IRQ_NONE;}if(status1){input_event(pmydev->pdev,EV_KEY,KEY_2,0);    //<--------------------上报事件，0按下input_sync(pmydev->pdev);                    //往核心层上报}else{input_event(pmydev->pdev,EV_KEY,KEY_2,1);    //<--------------------上报事件,1抬起input_sync(pmydev->pdev);                    //往核心层上报}return IRQ_HANDLED;
}int __init fs4412key2_init(void)
{int ret = 0;struct device_node *pnode = NULL;pnode = of_find_node_by_path("/fs4412-key2");if(NULL == pnode){printk("find node failed\n");return -1;}pgmydev = (struct fs4412key2_dev *)kmalloc(sizeof(struct fs4412key2_dev),GFP_KERNEL);if(NULL == pgmydev){printk("kmallc for struct fs4412key2_dev failed\n");return -1;}pgmydev->gpio = of_get_named_gpio(pnode,"key2-gpio",0);pgmydev->irqno = irq_of_parse_and_map(pnode,0);//<---------------------pgmydev->pdev = input_allocate_device();  //分配pdev空间set_bit(EV_KEY,pgmydev->pdev->evbit);     //设置事件set_bit(KEY_2,pgmydev->pdev->keybit);     //上报的哪个按键ret = input_register_device(pgmydev->pdev);//注册到系统ret = request_irq(pgmydev->irqno,key2_irq_handle,IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING,"fs4412key2",pgmydev);if(ret){printk("request_irq failed\n");input_unregister_device(pgmydev->pdev);  //反操作input_free_device(pgmydev->pdev);        //反操作kfree(pgmydev);pgmydev = NULL;return -1;}return 0;
}void __exit fs4412key2_exit(void)
{free_irq(pgmydev->irqno,pgmydev);input_unregister_device(pgmydev->pdev);    //反操作input_free_device(pgmydev->pdev);          //反操作kfree(pgmydev);pgmydev = NULL;
}MODULE_LICENSE("GPL");module_init(fs4412key2_init);
module_exit(fs4412key2_exit);

测试

testkey.2

#include <sys/types.h>
#include <sys/stat.h>
#include <linux/input.h>
#include <fcntl.h>
#include <unistd.h>#include <stdio.h>int main(int argc,char *argv[])
{int fd = -1;struct input_event evt;if(argc < 2){printf("Argument is too few\n");return 1;}/*open*/fd = open(argv[1],O_RDONLY);if(fd < 0){printf("open %s failed\n",argv[1]);return 2;}/*init mpu6050*/while(1){read(fd,&evt,sizeof(evt));if(evt.type == EV_KEY && evt.code == KEY_2){if(evt.value){printf("KEY2 DOWN\n");}else{printf("KEY2 UP\n");}}}/*close*/close(fd);fd = -1;return 0;
}

Makefile

ifeq ($(KERNELRELEASE),)ifeq ($(ARCH),arm)
KERNELDIR ?= /home/linux/Linux_4412/kernel/linux-3.14
ROOTFS ?= /opt/4412/rootfs
else
KERNELDIR ?= /lib/modules/$(shell uname -r)/build
endif
PWD := $(shell pwd)modules:$(MAKE) -C $(KERNELDIR) M=$(PWD) modulesmodules_install:$(MAKE) -C $(KERNELDIR) M=$(PWD) modules INSTALL_MOD_PATH=$(ROOTFS) modules_installclean:rm -rf  *.o  *.ko  .*.cmd  *.mod.*  modules.order  Module.symvers   .tmp_versionselseCONFIG_MODULE_SIG=nobj-m += fs4412_key2.oendif

编译拷贝到跟文件系统测试

四、mpu6050-input版代码解析

mpu6050_drv_input.c

注：绝对坐标的上报事件，如角速度加速度无变化核心层会屏蔽掉，除非有变化

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/i2c.h>
#include <linux/cdev.h>
#include <linux/wait.h>
#include <linux/sched.h>
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/input.h>
#include <linux/io.h>
#include <asm/uaccess.h>
#include <asm/atomic.h>#define SMPLRT_DIV 0x19
#define CONFIG 0x1A
#define GYRO_CONFIG 0x1B
#define ACCEL_CONFIG 0x1C#define ACCEL_XOUT_H 0x3B
#define ACCEL_XOUT_L 0x3C
#define ACCEL_YOUT_H 0x3D
#define ACCEL_YOUT_L 0x3E
#define ACCEL_ZOUT_H 0x3F
#define ACCEL_ZOUT_L 0x40
#define TEMP_OUT_H 0x41
#define TEMP_OUT_L 0x42
#define GYRO_XOUT_H 0x43
#define GYRO_XOUT_L 0x44
#define GYRO_YOUT_H 0x45
#define GYRO_YOUT_L 0x46
#define GYRO_ZOUT_H 0x47
#define GYRO_ZOUT_L 0x48#define PWR_MGMT_1  0x6Bstruct mpu6050_dev
{struct input_dev * pinput;   //<---------------------struct i2c_client *pclient;struct delayed_work work;    //可设置时间，到时间work回调函数会被调用
};struct mpu6050_dev *pgmydev = NULL;int mpu6050_read_byte(struct i2c_client *pclt,unsigned char reg)
{int ret = 0;char txbuf[1] = {reg};char rxbuf[1] = {0};struct i2c_msg msg[2] = {{pclt->addr,0,1,txbuf},{pclt->addr,I2C_M_RD,1,rxbuf}};ret = i2c_transfer(pclt->adapter,msg,ARRAY_SIZE(msg));if(ret < 0){printk("ret = %d,in mpu6050_read_byte\n",ret);return ret;}return rxbuf[0];
}int mpu6050_write_byte(struct i2c_client *pclt,unsigned char reg,unsigned char val)
{int ret = 0;char txbuf[2] = {reg,val};struct i2c_msg msg[1] = {{pclt->addr,0,2,txbuf},};ret = i2c_transfer(pclt->adapter,msg,ARRAY_SIZE(msg));if(ret < 0){printk("ret = %d,in mpu6050_write_byte\n",ret);return ret;}return 0;
}void mpu6050_work_func(struct work_struct *pwk)
{struct mpu6050_dev *pmydev = container_of((struct delayed_work *)pwk,struct mpu6050_dev,work);unsigned short ax = 0;unsigned short ay = 0;unsigned short az = 0;unsigned short gx = 0;unsigned short gy = 0;unsigned short gz = 0;unsigned short temp = 0;ax = mpu6050_read_byte(pmydev->pclient,ACCEL_XOUT_L);ax = mpu6050_read_byte(pmydev->pclient,ACCEL_XOUT_H) << 8;input_report_abs(pmydev->pinput,ABS_X,ax);    //<-----上报分量ay = mpu6050_read_byte(pmydev->pclient,ACCEL_YOUT_L);ay = mpu6050_read_byte(pmydev->pclient,ACCEL_YOUT_H) << 8;input_report_abs(pmydev->pinput,ABS_Y,ay);az = mpu6050_read_byte(pmydev->pclient,ACCEL_ZOUT_L);az = mpu6050_read_byte(pmydev->pclient,ACCEL_ZOUT_H) << 8;input_report_abs(pmydev->pinput,ABS_Z,az);gx = mpu6050_read_byte(pmydev->pclient,GYRO_XOUT_L);gx = mpu6050_read_byte(pmydev->pclient,GYRO_XOUT_H) << 8;input_report_abs(pmydev->pinput,ABS_RX,gx);gy = mpu6050_read_byte(pmydev->pclient,GYRO_YOUT_L);gy = mpu6050_read_byte(pmydev->pclient,GYRO_YOUT_H) << 8;input_report_abs(pmydev->pinput,ABS_RY,gy);gz = mpu6050_read_byte(pmydev->pclient,GYRO_ZOUT_L);gz = mpu6050_read_byte(pmydev->pclient,GYRO_ZOUT_H) << 8;input_report_abs(pmydev->pinput,ABS_RZ,gz);temp = mpu6050_read_byte(pmydev->pclient,TEMP_OUT_L);temp = mpu6050_read_byte(pmydev->pclient,TEMP_OUT_H) << 8;input_report_abs(pmydev->pinput,ABS_MISC,temp);input_sync(pmydev->pinput);        //<----------绝对坐标真正上报，如角速度加速度无变化核心层会屏蔽掉，除非有变化schedule_delayed_work(&pgmydev->work,msecs_to_jiffies(1000));  //<---------延时1秒调用
}void init_mpu6050(struct i2c_client *pclt)
{mpu6050_write_byte(pclt,PWR_MGMT_1,0x00);mpu6050_write_byte(pclt,SMPLRT_DIV,0x07);mpu6050_write_byte(pclt,CONFIG,0x06);mpu6050_write_byte(pclt,GYRO_CONFIG,0xF8);mpu6050_write_byte(pclt,ACCEL_CONFIG,0x19);
}static int mpu6050_probe(struct i2c_client *pclt,const struct i2c_device_id *pid)
{int ret = 0;pgmydev = (struct mpu6050_dev *)kmalloc(sizeof(struct mpu6050_dev),GFP_KERNEL);if(NULL == pgmydev){printk("kmalloc failed\n");return -1;}memset(pgmydev,0,sizeof(struct mpu6050_dev));pgmydev->pclient = pclt;init_mpu6050(pgmydev->pclient);pgmydev->pinput = input_allocate_device();     //<-----------------set_bit(EV_ABS,pgmydev->pinput->evbit);        //<-----------------设置绝对坐标类事件input_set_abs_params(pgmydev->pinput,ABS_X,-32768,32767,0,0);   //<--------32768,32767代表取值范围,0误差范围,0代表不使用平滑参数值input_set_abs_params(pgmydev->pinput,ABS_Y,-32768,32767,0,0);input_set_abs_params(pgmydev->pinput,ABS_Z,-32768,32767,0,0);input_set_abs_params(pgmydev->pinput,ABS_RX,-32768,32767,0,0);input_set_abs_params(pgmydev->pinput,ABS_RY,-32768,32767,0,0);input_set_abs_params(pgmydev->pinput,ABS_RZ,-32768,32767,0,0);input_set_abs_params(pgmydev->pinput,ABS_MISC,-32768,32767,0,0); //温度ret = input_register_device(pgmydev->pinput);  //<-----------------if(ret){printk("input_register_device failed\n");input_free_device(pgmydev->pinput);pgmydev->pinput = NULL;kfree(pgmydev);pgmydev = NULL;return -1;}INIT_DELAYED_WORK(&pgmydev->work,mpu6050_work_func);   //<-----------------schedule_delayed_work(&pgmydev->work,msecs_to_jiffies(1000));  //<-----------------1s后函数会被调用return 0;
}static int mpu6050_remove(struct i2c_client *pclt)
{cancel_delayed_work(&pgmydev->work);        //<-----------------取消每隔1秒的函数input_unregister_device(pgmydev->pinput);   //<-----------------input_free_device(pgmydev->pinput);pgmydev->pinput = NULL;kfree(pgmydev);pgmydev = NULL;return 0;
}struct of_device_id mpu6050_dt[] = 
{{.compatible = "invensense,mpu6050"},{}
};struct i2c_device_id mpu6050_ids[] = 
{{"mpu6050",0},{}
};struct i2c_driver mpu6050_driver = 
{.driver = {.name = "mpu6050",.owner = THIS_MODULE,.of_match_table = mpu6050_dt,},.probe = mpu6050_probe,.remove = mpu6050_remove,.id_table = mpu6050_ids,
};#if 0
int __init mpu6050_driver_init(void)
{i2c_add_driver(&mpu6050_driver);
}void __exit mpu6050_driver_exit(void)
{i2c_del_driver(&mpu6050_driver);
}
module_init(mpu6050_driver_init);
module_exit(mpu6050_driver_exit);
#else
module_i2c_driver(mpu6050_driver);
#endifMODULE_LICENSE("GPL");

testmpu6050_input.c

#include <sys/types.h>
#include <sys/stat.h>
#include <linux/input.h>
#include <fcntl.h>
#include <unistd.h>#include <stdio.h>int main(int argc,char *argv[])
{int fd = -1;struct input_event evt;if(argc < 2){printf("Argument is too few\n");return 1;}/*open*/fd = open(argv[1],O_RDONLY);if(fd < 0){printf("open %s failed\n",argv[1]);return 2;}/*init mpu6050*/while(1){read(fd,&evt,sizeof(evt));if(evt.type == EV_ABS){switch(evt.code){case ABS_X:printf("Accel-x:%d\n",evt.value);break;case ABS_Y:printf("Accel-y:%d\n",evt.value);break;case ABS_Z:printf("Accel-z:%d\n",evt.value);break;case ABS_RX:printf("Gyro-x:%d\n",evt.value);break;case ABS_RY:printf("Gyro-y:%d\n",evt.value);break;case ABS_RZ:printf("Gyro-z:%d\n",evt.value);break;case ABS_MISC:printf("Temp:%d\n",evt.value);break;}}}/*close*/close(fd);fd = -1;return 0;
}

Makefile

ifeq ($(KERNELRELEASE),)ifeq ($(ARCH),arm)
KERNELDIR ?= /home/linux/Linux_4412/kernel/linux-3.14
ROOTFS ?= /opt/4412/rootfs
else
KERNELDIR ?= /lib/modules/$(shell uname -r)/build
endif
PWD := $(shell pwd)modules:$(MAKE) -C $(KERNELDIR) M=$(PWD) modulesmodules_install:$(MAKE) -C $(KERNELDIR) M=$(PWD) modules INSTALL_MOD_PATH=$(ROOTFS) modules_installclean:rm -rf  *.o  *.ko  .*.cmd  *.mod.*  modules.order  Module.symvers   .tmp_versionselseCONFIG_MODULE_SIG=nobj-m += mpu6050_drv_input.oendif

编译拷贝到rootfs