x4412&ibox项目实战49－input子系统之按键驱动实验

armeasy · 发表于 2014-10-17 15:48:21

Linux 的输入子系统不仅支持鼠标、键盘等常规输入设备,而且还支持蜂鸣器、触摸屏等设备。输入子系统又叫input子系统。其构建非常灵活,只需要调用一些简单的函数,就可以将一个输入设备的功能呈现给应用程序。其结构图如下：

编写一个input子系统驱动程序，用于检测按键的中断，并将按键信息上报给应用。在kernel/drivers/input/keyboard目录下新建x4412_keys.c文件，编辑内容如下：

#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/cdev.h>
#include <asm/uaccess.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <mach/gpio.h>
#include <linux/input.h>
/* 定义并初始化等待队列头 */
static DECLARE_WAIT_QUEUE_HEAD(button_waitq);
static struct class *cdrv_class;
static struct device *cdrv_device;
void x4412_eint_do_tasklet(unsigned long data);
DECLARE_TASKLET(x4412_eint_tasklet,x4412_eint_do_tasklet,0);
typedef struct pin_desc
{
unsigned int pin;
unsigned int key_val;
}pin_desc;
static struct pin_desc pins_desc[6] =
{
{EXYNOS4_GPX1(0),0x01},//LEFT
{EXYNOS4_GPX1(3),0x02},//RIGHT
{EXYNOS4_GPX1(2),0x03},//UP
{EXYNOS4_GPX1(1),0x04},//DOWN
{EXYNOS4_GPX1(5),0x05},//MENU
{EXYNOS4_GPX1(4),0x06},//BACK
};
static struct input_dev *button_dev; /*输入设备结构体*/
struct pin_desc *pin_desc_p;
static int ev_press = 0;
int major;
void x4412_eint_do_tasklet(unsigned long data)
{
unsigned int pinval,state;
pinval = gpio_get_value(pin_desc_p->pin);
if(pinval)
{
state = 0;
}
else
{
state = 1;
}
ev_press = 1;
printk("int:pin_desc_p->key_val=0x%x\r\n",pin_desc_p->key_val);
input_report_key(button_dev, BTN_0, state); /*向输入子系统报告产生按键事件*/
input_sync(button_dev); /*通知接收者,一个报告发送完毕*/
wake_up_interruptible(&button_waitq);
}
/* 用户中断处理函数 */
static irqreturn_t x4412_buttons_irq(int irq, void *dev_id)
{
pin_desc_p = (struct pin_desc *)dev_id;
tasklet_schedule(&x4412_eint_tasklet);
return IRQ_HANDLED;
}
static int x4412_eint_open(struct inode * inode, struct file * filp)
{
return 0;
}
static int x4412_eint_release(struct inode *inode, struct file *file)
{
int irq;
irq = gpio_to_irq(pins_desc[0].pin);
free_irq(irq, &pins_desc[0]);
irq = gpio_to_irq(pins_desc[1].pin);
free_irq(irq,&pins_desc[1]);
irq = gpio_to_irq(pins_desc[2].pin);
free_irq(irq,&pins_desc[2]);
irq = gpio_to_irq(pins_desc[3].pin);
free_irq(irq, &pins_desc[3]);
irq = gpio_to_irq(pins_desc[4].pin);
free_irq(irq,&pins_desc[4]);
irq = gpio_to_irq(pins_desc[5].pin);
free_irq(irq,&pins_desc[5]);
return 0;
}
static const struct file_operations x4412_eint_fops =
{
.owner = THIS_MODULE,
.open = x4412_eint_open,
.release = x4412_eint_release,
};
/* 驱动入口函数 */
static int x4412_eint_init(void)
{
int ret,irq;
major = register_chrdev(0, "x4412-key", &x4412_eint_fops);
cdrv_class = class_create(THIS_MODULE, "x4412-eint");
cdrv_device = device_create(cdrv_class, NULL, MKDEV(major, 0), NULL, "x4412-eint");
irq = gpio_to_irq(pins_desc[0].pin);
ret = request_irq(irq, x4412_buttons_irq,IRQ_TYPE_EDGE_BOTH, "LEFT", &pins_desc[0]);
if(ret)
printk("request irq_eint8 error!\r\n");
irq = gpio_to_irq(pins_desc[1].pin);
ret = request_irq(irq, x4412_buttons_irq,IRQ_TYPE_EDGE_BOTH, "RIGHT",&pins_desc[1]);
if(ret)
printk("request irq_eint11 error!\r\n");
irq = gpio_to_irq(pins_desc[2].pin);
ret = request_irq(irq, x4412_buttons_irq, IRQ_TYPE_EDGE_BOTH, "UP", &pins_desc[2]);
if(ret)
printk("request irq_eint10 error!\r\n");
irq = gpio_to_irq(pins_desc[3].pin);
ret = request_irq(irq, x4412_buttons_irq, IRQ_TYPE_EDGE_BOTH, "DOWN", &pins_desc[3]);
if(ret)
printk("request irq_eint9 error!\r\n");
irq = gpio_to_irq(pins_desc[4].pin);
ret = request_irq(irq, x4412_buttons_irq, IRQ_TYPE_EDGE_BOTH, "MENU", &pins_desc[4]);
if(ret)
printk("request irq_eint13 error!\r\n");
irq = gpio_to_irq(pins_desc[5].pin);
ret = request_irq(irq, x4412_buttons_irq, IRQ_TYPE_EDGE_BOTH, "BACK", &pins_desc[5]);
if(ret)
printk("request irq_eint12 error!\r\n");
pin_desc_p = kmalloc(sizeof(struct pin_desc), GFP_KERNEL);
if(!pin_desc_p)
{
return -ENOMEM;
}
button_dev = input_allocate_device(); /*分配一个设备结构体*/
if (!button_dev)
{
printk(KERN_ERR "x4412-key.c: Not enough memory\n");
ret = -ENOMEM;
goto err_free_irq;
}
button_dev->name = "x4412-key";
button_dev->evbit[0] = BIT_MASK(EV_KEY); /*设置按键信息*/
button_dev->keybit[BIT_WORD(BTN_0)] = BIT_MASK(BTN_0);
ret = input_register_device(button_dev); /*注册一个输入设备*/
if (ret)
{
printk(KERN_ERR "x4412-key.c: Failed to register device\n");
goto err_free_dev;
}
return 0;
err_free_dev:
input_free_device(button_dev);
err_free_irq:
free_irq(irq, x4412_buttons_irq);
return ret;
}
/* 驱动出口函数 */
static void x4412_eint_exit(void)
{
int irq;
irq = gpio_to_irq(pins_desc[0].pin);
free_irq(irq, &pins_desc[0]);
irq = gpio_to_irq(pins_desc[1].pin);
free_irq(irq,&pins_desc[1]);
irq = gpio_to_irq(pins_desc[2].pin);
free_irq(irq,&pins_desc[2]);
irq = gpio_to_irq(pins_desc[3].pin);
free_irq(irq, &pins_desc[3]);
irq = gpio_to_irq(pins_desc[4].pin);
free_irq(irq,&pins_desc[4]);
irq = gpio_to_irq(pins_desc[5].pin);
free_irq(irq,&pins_desc[5]);
unregister_chrdev(major, "x4412-key");
device_unregister(cdrv_device); //卸载类下的设备
class_destroy(cdrv_class); //卸载类
}
module_init(x4412_eint_init); //用于修饰入口函数
module_exit(x4412_eint_exit); //用于修饰出口函数
MODULE_AUTHOR("www.9tripod.com");
MODULE_LICENSE("GPL");

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结合源码，可以总结出添加一个输入子系统的几大步骤：

第一步：定义一个输入子系统结构体：

static struct input_dev *button_dev;

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第二步：通过input_allocate_device函数分配一个输入子系统结构体：

button_dev = input_allocate_device();

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第三步：定义输入子系统名称：

button_dev->name = "x4412-key";

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第四步：设置产生的事件及键值：

button_dev->evbit[0] = BIT_MASK(EV_KEY); /*设置按键信息*/
button_dev->keybit[BIT_WORD(BTN_0)] = BIT_MASK(BTN_0);

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第五步：注册一个输入设备：

ret = input_register_device(button_dev);

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第六步：当有输入事件产生时，向输入子系统报告产生的事件：

input_report_key(button_dev, BTN_0, state);

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第七步：通知接收者：

input_sync(button_dev);

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修改kernel/drivers/input/keyboard/Makefile文件，找到如下内容：

obj-$(CONFIG_KEYBOARD_GPIO) += gpio_keys.o

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修改为：

obj-$(CONFIG_KEYBOARD_GPIO) += x4412_keys.o

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在make menuconfig指令中，找到

Device Drivers --->Input device support --->Keyboards --->GPIO Buttons

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将驱动设置成模块，编译内核后，将会在kernel/drivers/input/keyboard目录下生成目标文件x4412_keys.ko。

在ubuntu用户目录或samba目录下新建测试程序x4412_keys-app.c，用于读取按键键值。编辑内容如下：

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/select.h>
#include <sys/time.h>
#include <errno.h>
#include <linux/input.h>
int main(void)
{
int buttons_fd;
int key_value,i=0,count;
struct input_event ev_key;
buttons_fd = open("/dev/input/event3", O_RDWR);
if (buttons_fd < 0)
{
perror("open device buttons");
exit(1);
}
for (;;)
{
count = read(buttons_fd,&ev_key,sizeof(struct input_event));
for(i=0; i<(int)count/sizeof(struct input_event); i++)
if(ev_key.type==EV_KEY)
printf("type:%d,code:%d,value:%d\n", ev_key.type,ev_key.code-1,ev_key.value);
if(ev_key.type==EV_SYN)
printf("syn event\n\n");
}
close(buttons_fd);
return 0;
}

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测试程序通过open函数打开输入子系统的设备节点，通过如下指令查询驱动的设备节点：

cat /proc/bus/input/devices

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查询结果如下：

[root@x4412 mnt]# cat /proc/bus/input/devices
I: Bus=0018 Vendor=dead Product=beef Version=28bb
N: Name="ft5x06-ts"
P: Phys=input/ts
S: Sysfs=/devices/virtual/input/input0
U: Uniq=
H: Handlers=kbd event0
B: PROP=0
B: EV=b
B: KEY=400 0 4 0 2000000 0 40000800 40 0 0 0
B: ABS=2650000 1000003
I: Bus=0000 Vendor=0000 Product=0000 Version=0000
N: Name="gsensor"
P: Phys=
S: Sysfs=/devices/virtual/input/input1
U: Uniq=
H: Handlers=event1
B: PROP=0
B: EV=9
B: ABS=100 7
I: Bus=0019 Vendor=0000 Product=0000 Version=0000
N: Name="gpio_ir_recv"
P: Phys=
S: Sysfs=/devices/virtual/rc/rc0/input2
U: Uniq=
H: Handlers=kbd event2
B: PROP=0
B: EV=100013
B: KEY=60000 2008000 0 40400800 1e16c0 0 0 10004ffc
B: MSC=10
I: Bus=0000 Vendor=0000 Product=0000 Version=0000
N: Name="x4412-key"
P: Phys=
S: Sysfs=/devices/virtual/input/input3
U: Uniq=
H: Handlers=event3
B: PROP=0
B: EV=3
B: KEY=1 0 0 0 0 0 0 0 0
[root@x4412 mnt]#

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这些都是输入子系统设备，其中x4412-key对应的设备节点为event3。编译测试程序，加载驱动模块后，使用测试程序测试效果如下：

[root@x4412 mnt]# insmod x4412-key.ko
[ 47.368709] input: x4412-key as /devices/virtual/input/input3
[root@x4412 mnt]# ./x4412-key-app
[ 53.388507] int:pin_desc_p->key_val=0x1
count=16
type:1,code:255,value:1
count=16
syn event

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mzucore · 发表于 2014-12-12 12:19:52

非常感谢您的分享~~~~~~~~

tongyongli1986 · 发表于 2014-12-15 15:26:46

怎么才能看见啊？？