按键驱动：platform架构

这篇文章接着上篇文章介绍按键驱动的第二种实现方法，就是应用驱动和设备分离的思想。

话不多说，直接上程序：

整个程序的结构如下：

.
├── dev
│   ├── key_dev.c
│   └── Makefile
├── dri
│   ├── key_dri.c
│   └── Makefile
└── test
    └── test.c

key_dev.c

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <mach/regs-gpio.h>
#include <mach/hardware.h>
#include <linux/irq.h>

struct jz2440_key_t
{
    const char *name;
    unsigned int pin;
    unsigned char key_val;
    unsigned int irq;      /*按键的中断号 */
    unsigned int setting;  /* 按键对应的功能的掩码 */
    unsigned int id;
};

struct jz2440_key_platform
{
    struct jz2440_key_t *buttonp;
    int button_num;
};

/*
 * key s2 is GPF0 -- EINT0
 * key s3 is GPF2 -- EINT2
 * key s4 is GPG3 -- EINT11
 * key s5 is GPG11-- EINT19
 */
struct jz2440_key_t key_table[] =
{
    {"Button S2", S3C2410_GPF(0),  0, IRQ_EINT(0),  S3C2410_GPF0_EINT0,   0},
    {"Button S3", S3C2410_GPF(2),  0, IRQ_EINT(2),  S3C2410_GPF2_EINT2,   1},
    {"Button S4", S3C2410_GPG(3),  0, IRQ_EINT(11), S3C2410_GPG3_EINT11,  2},
    {"Button S5", S3C2410_GPG(11), 0, IRQ_EINT(19), S3C2410_GPG11_EINT19, 3},
};

struct jz2440_key_platform jz2440_key = {
    .buttonp = key_table,
    .button_num = ARRAY_SIZE(key_table),
};

static void device_release(struct device *dev)
{
    printk("platform: device release\n");
};

struct platform_device jz2440_key_dev = {
    .id = -1,
    .name = "jz2440_button", /* 用于匹配的名字 */
    .dev = {
        .release = device_release,
        .platform_data = &jz2440_key, /* 是 void * 类型 */
    }
};

static int __init jz2440_button_dev_init(void)
{
    printk("dev init\n");
    platform_device_register(&jz2440_key_dev);
    return 0;
}

static void __exit jz2440_button_dev_exit(void)
{
    printk("dev exit\n");
    platform_device_unregister(&jz2440_key_dev);
}

module_init(jz2440_button_dev_init);
module_exit(jz2440_button_dev_exit);

MODULE_LICENSE("Dual BSD/GPL");

说明：

    【1】要想将自己定义的结构体数组传递给别的模块，需要首地址和数组的元素个数，所以又定义了一个 jz2440_key 的结构体

Makefile

ifeq ($(KERNELRELEASE),)

#KERNELDIR ?= /lib/modules/$(shell uname -r)/build 
KERNELDIR ?= ~/wor_lip/linux-3.4.112
PWD := $(shell pwd)

modules:
	$(MAKE) -C $(KERNELDIR) M=$(PWD) modules

modules_install:
	$(MAKE) -C $(KERNELDIR) M=$(PWD) modules_install

clean:
	rm -rf *.o *~ core .depend .*.cmd *.ko *.mod.c .tmp_versions modules* Module*

.PHONY: modules modules_install clean

else
	obj-m := key_dev.o
endif

key_dri.c

#include <linux/module.h>  
#include <linux/kernel.h>  
#include <linux/fs.h>  
#include <linux/init.h>  
#include <linux/delay.h>  
#include <linux/irq.h>  
#include <asm/uaccess.h>  
#include <asm/irq.h>  
#include <asm/io.h>  
#include <linux/poll.h>
#include <linux/interrupt.h>
#include <mach/regs-gpio.h>
#include <mach/hardware.h>
#include <linux/wait.h>
#include <linux/device.h>
#include <mach/gpio.h>
#include <linux/interrupt.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/platform_device.h>

#define DEVICE_NAME "jz2440_button_drv"

static unsigned char key_vals[4];   /* 保存要传递给用户空间的4个按键值 */
static struct timer_list key_timers[4];
#define KEYDOWN_DELAY (HZ/100)  /* 按键按下时的去抖延时是10ms */
#define KEYUP_DELAY   (HZ/200)  /* 按键抬起时的去抖延时是5ms */

struct jz2440_key_t
{
    const char *name;
    unsigned int pin;
    unsigned char key_val;
    unsigned int irq;      /*按键的中断号 */
    unsigned int setting;  /* 按键对应的功能的掩码 */
    unsigned int id;
};

struct jz2440_key_platform
{
    struct jz2440_key_t *buttonp;
    int button_num;
};

struct jz2440_key_t *key_tablep;
struct jz2440_key_platform *key_platformp;

static struct class *button_drv_class;
int major;

unsigned int key_pressed;
unsigned int key_pressed_middle_flag;

static DECLARE_WAIT_QUEUE_HEAD(button_waitq);

int jz2440_key_dri_probe(struct platform_device *dev)
{
    key_platformp = (struct jz2440_key_platform *)dev->dev.platform_data;
    key_tablep = key_platformp->buttonp;

    printk("platform: match ok!\n");
    return 0;
}

int jz2440_key_dri_remove(struct platform_device *dev)
{
    printk("platform: driver remove\n");
    return 0;
}

struct platform_driver jz2440_key_dri = {
    .probe = jz2440_key_dri_probe,
    .remove = jz2440_key_dri_remove,
    .driver = {
        .name = "jz2440_button"
    },
};

irqreturn_t irq_handler(int irq, void *dev_id)
{
    int key_num = *((int *)dev_id);
    unsigned int pinval = s3c2410_gpio_getpin(key_tablep[key_num].pin);

    if (!pinval)
    {
        key_pressed_middle_flag = 1;

        mod_timer(&key_timers[key_num], jiffies + KEYDOWN_DELAY);
    }else
    {
        key_pressed_middle_flag = 0;

        mod_timer(&key_timers[key_num], jiffies + KEYUP_DELAY);
    }

    return IRQ_RETVAL(IRQ_HANDLED);
}

void fun_timer(unsigned long arg)
{
    int pinval = s3c2410_gpio_getpin(key_tablep[arg].pin);

    if (!pinval)
    {
        if (key_pressed_middle_flag == 1)
        {
            /*printk("pree down\n");*/

            key_pressed = 1;
            key_tablep[arg].key_val = 1;

            wake_up_interruptible(&button_waitq);  /* 唤醒如果读而引起的阻塞 */
        }
    }else
    {
        if (key_pressed_middle_flag == 0)
        {
            /*printk("pree up\n");*/

            key_pressed = 0;
            key_tablep[arg].key_val = 0;
        }
    }
}

static int jz2440_button_drv_open(struct inode *inode, struct file *filp)
{
    int i;
    for (i = 0; i < key_platformp->button_num; i++)
    {
        s3c2410_gpio_cfgpin(key_tablep[i].pin, key_tablep[i].setting);  /* 将芯片引脚设置成中断 */
        irq_set_irq_type(key_tablep[i].irq, IRQ_TYPE_EDGE_BOTH);  /* 下降沿触发 */
        request_irq(key_tablep[i].irq, irq_handler, IRQF_DISABLED, key_tablep[i].name, &key_tablep[i].id);  /* 向系统内核申请快速中断 */

        setup_timer(&key_timers[i], fun_timer, i);
    }
    printk("button_drv_open\n");

    return 0;
}

static int jz2440_button_drv_close(struct inode *inode, struct file *filp)
{
    int i;
    for (i = 0; i < key_platformp->button_num; i++)
    {
        del_timer(&key_timers[i]);

        disable_irq(key_tablep[i].irq);
        free_irq(key_tablep[i].irq, &key_tablep[i].id);
    }

    return 0;
}

/* 读的时候按键的数量必须是 4 ,返回成功读取的个数 */
ssize_t jz2440_button_drv_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
{
    int j;
    unsigned long ret;
    if (size != sizeof(key_vals))
        return -EINVAL;

    /* 如果是非阻塞的读 */
    if (file->f_flags & O_NONBLOCK)
    {
        if (!key_pressed) /* 非阻塞的读,按键没有按下过 */
            return -EAGAIN;
    }
    else if (!key_pressed) /* 阻塞的读,按键没有按下过 */
    {
        wait_event_interruptible(button_waitq, key_pressed);
    }

    key_pressed = 0;
    for (j = 0; j < key_platformp->button_num; j++)
    {
        key_vals[j] = key_tablep[j].key_val;
    }

    ret = copy_to_user(buf, key_vals, size); /* 返回key_vals数组数据到用户空间 */

    return ret ? -EFAULT : min(sizeof(key_vals), size);
}

unsigned int jz2440_button_drv_poll (struct file *filp, struct poll_table_struct *wait)
{
    unsigned int mask = 0;
    poll_wait(filp, &button_waitq, wait);/* 加读等待队列头 */  

    if (key_pressed)
        mask |= POLLIN | POLLRDNORM; /* 标示数据可获得 */  

    return mask;  
}

static struct file_operations button_drv_fops =
{
    .owner = THIS_MODULE,
    .open  = jz2440_button_drv_open,
    .release = jz2440_button_drv_close,
    .read  = jz2440_button_drv_read,
    .poll  = jz2440_button_drv_poll,
};

int button_drv_init(void)
{
    platform_driver_register(&jz2440_key_dri);

    /* auto choice major */
    major = register_chrdev(0, DEVICE_NAME, &button_drv_fops);
    if (major < 0)
    {
        printk("jz2440 button driver can't register major number!\n");
        return major;
    }

    button_drv_class = class_create(THIS_MODULE, DEVICE_NAME);
    if (IS_ERR(button_drv_class))
    {
        printk("error, fail to init button_drv_class");
        return -1;
    }
    device_create(button_drv_class, NULL, MKDEV(major, 0), NULL, DEVICE_NAME);

    printk("BUTTON_DRV initialized! \n");

    return 0;
}

void button_drv_exit(void)
{
    platform_driver_unregister(&jz2440_key_dri);

    device_destroy(button_drv_class, MKDEV(major, 0)); //删掉设备节点
    class_destroy(button_drv_class);  //注销类

    unregister_chrdev(major, DEVICE_NAME);  //卸载驱动

    printk("exit is finished.\n");
}

module_init(button_drv_init);
module_exit(button_drv_exit);
MODULE_LICENSE("GPL");

说明：

    【1】在 probe 函数中想要用到匹配好的设备文件中的元素，直接使用 platform_device 的指针

    【2】在调试过程中在申请了中断后，可以用 cat /proc/interrupt 查看申请的中断，显示如下

           CPU0       
 16:          2  s3c-ext0  Button S2
 18:          2  s3c-ext0  Button S3
 24:          0       s3c  s3c2410-rtc tick
 30:      24994       s3c  S3C2410 Timer Tick
 32:          0       s3c  s3c2410-lcd
 37:          0       s3c  s3c-mci
 42:          0       s3c  ohci_hcd:usb1
 43:          8       s3c  s3c2440-i2c
 46:          0       s3c  s3c2410-rtc alarm
 51:       2805   s3c-ext  eth0
 55:          2   s3c-ext  Button S4
 60:          1   s3c-ext  s3c-mci
 63:          2   s3c-ext  Button S5

第一列是中断号，第二列是中断发生的次数，第三列是，第四列是中断的名字

    【3】这里有个现象，也不知道是不是问题，当 free_irq 之后，发现中断并没有在列表中消失，只是名字消失了。

    【4】这个函数的 init 和 exit 中对字符设备的注册和释放以及设备节点的创建还是有点麻烦，可以查看 混杂设备驱动 进行 混杂设备驱动改写，可以减少不少代码。

Makefile 中改一下目标文件即可

test.c

#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/select.h>
#include <fcntl.h>
#include <unistd.h>
#include <signal.h>

int fd;
fd_set rds;

void stop(int signo)
{
    close(fd);
    FD_CLR(fd, &rds);
    _exit(0);
}

int main(int argc, const char *argv[])
{
    unsigned char data_buf[4];

    signal(SIGINT, stop); /* 按下ctrl+c,调用stop函数 */

    /* 阻塞的读 */
    if ((fd = open("/dev/jz2440_button_drv", O_RDONLY)) < 0)
    {
        perror("fail to open");  
        return -1;  
    }

    while (1)
    {
        int ret, i;

        FD_ZERO(&rds);
        FD_SET(fd, &rds);  /* 将fd文件描述符添加到rds这个文件描述符集中去 */

        ret = select(fd + 1, &rds, NULL, NULL, NULL);
        
        printf("doing\n");

        if (ret < 0)
        {
            printf("read jz2440 button fail!\n");
            continue;
        }else if (ret == 0)
        {
            printf("read jz2440 button time out!\n");
            continue;
        }
        if (FD_ISSET(fd, &rds))
        {
            ret = read(fd, data_buf, sizeof(data_buf));
            if (ret < 4)
            {
                printf("read not complete.\n");
                break;
            }

            for (i = 0 ; i < 4; i++)
            {
                printf("S%d:%d ", 2 + i, data_buf[i]);
            }
                printf("\n");
        }
    }
    return 0;
}

这个文件的编译命令：

arm-none-linux-gnueabi-gcc test.c -o button -march=armv4t

实验结果：

[root@lip ~]# insmod  key_dev.ko 
dev init
[root@lip ~]# insmod key_dri.ko 
platform: match ok!
BUTTON_DRV initialized! 
[root@lip ~]# ./button 
button_drv_open
doing
S2:1 S3:0 S4:0 S5:0 
doing
S2:0 S3:1 S4:0 S5:0 
doing
S2:0 S3:0 S4:1 S5:0 
doing
S2:0 S3:0 S4:0 S5:1