一个简单的keyboard驱动_keybord驱动-优快云博客

本文链接：https://blog.youkuaiyun.com/lamdoc/article/details/9341969

本文介绍了一种基于CPLD的按键驱动程序的设计与实现方法。该驱动支持包括F1至F4、HOME、方向键等在内的多个按键。通过定时器轮询和中断处理相结合的方式，实现了按键状态的检测及事件上报。

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这个驱动使能了几个CPLD控制的按键，F1， F2，F3，F4， HOME， UP， DOWN，LEFT，RIGHT， ESC， ENTER。

1.cpld_kpd_probe()

static int cpld_kpd_probe(struct platform_device *pdev)
{
        struct input_dev *cpld_input_dev;
        int i, irq;
        int retval;

        dprintk("%s.\n", __func__);

        key_pad_enabled = 0;
        cpld_kpd_dev = kmalloc(sizeof(struct cpld_kpd), GFP_KERNEL);

        cpldkpd_keycodes = key_mapping;
        cpldkpd_keycodes_size = 4*3;
        if ((key_mapping == (void *)0)
                || (cpldkpd_keycodes_size == 0)) {
                retval = -ENODEV;
                goto err1;
        }

        cpld_input_dev=input_allocate_device();
        if(!cpld_kpd_dev || !cpld_input_dev) {
                retval = -ENOMEM;
                goto err1;
        }

        platform_set_drvdata(pdev, cpld_kpd_dev);
        cpld_kpd_dev->input = cpld_input_dev;

        cpld_input_dev->keycode = (void *)cpldkpd_keycodes;
        cpld_input_dev->keycodesize = sizeof(cpldkpd_keycodes[0]);
        cpld_input_dev->keycodemax = cpldkpd_keycodes_size;
        cpld_input_dev->name = "cpldkpd";
        cpld_input_dev->id.bustype = BUS_HOST;

        retval = input_register_device(cpld_input_dev);
        if(retval < 0) {
                printk(KERN_ERR
                        "cpld_input_dev: failed to register input device.\n");
                goto err2;
        }

        __set_bit(EV_KEY, cpld_input_dev->evbit);

        for (i = 0; i < cpldkpd_keycodes_size; i++)
                __set_bit(cpldkpd_keycodes[i], cpld_input_dev->keybit);

        cpld_kpd_dev->poll_timer.expires = jiffies + KScanRate;
        cpld_kpd_dev->poll_timer.function = cpld_kpd_handle_timer;
        /* Initialize the polling timer */
        init_timer(&cpld_kpd_dev->poll_timer);

        /* map CPLD memory */
        cpld_kpd_dev->base = ioremap(CPLD_BASE_ADDR, 64);
        if(!cpld_kpd_dev->base) {
                retval = -ENOMEM;
                goto err2;
        }

        irq = setup_gpio_irq();
        retval = request_irq(irq, cpld_kpd_interrupt, 0, MOD_NAME, MOD_NAME);
        if(retval) {
                pr_debug("CPLDKPD: request_irq(%d) error %d\n",
                                irq, retval);
                goto err3;
        }

        key_pad_enabled = 1;
        device_init_wakeup(&pdev->dev, 1);

        return 0;

err3:
        free_irq(irq, MOD_NAME);
err2:
        input_unregister_device(cpld_input_dev);
err1:
        input_free_device(cpld_input_dev);
        kfree(cpld_kpd_dev);

        return retval;
}

这算是个标准的keyboard input设备的probe函数。

cpld_kpd_dev是个全局变量，原型如下：

/* Keypad private data structure */
struct cpld_kpd {
        struct input_dev *input;

        /* Timer used for keypad polling */
        struct timer_list poll_timer;
        int irq;
        unsigned int n_keys;

        /* The base address */
        void __iomem *base;
};

struct cpld_kpd *cpld_kpd_dev;

input_dev: 表示是个输入设备。

poll_timer.：因为整了一个定时器，所以有一个timer_list

irq是中断号，

nkeys：是按键的个数

base：是需要ioremap的映射CPLD的地址，用来读取按键寄存器值的。

然后分配一个input_dev, 接着是初始化和注册输入设备。

然后是注册中断。

初始化定时器：

        cpld_kpd_dev->poll_timer.expires = jiffies + KScanRate;
        cpld_kpd_dev->poll_timer.function = cpld_kpd_handle_timer;
        /* Initialize the polling timer */
        init_timer(&cpld_kpd_dev->poll_timer);

remap CPLD内存空间，访问CPLD寄存器需要：

        /* map CPLD memory */
        cpld_kpd_dev->base = ioremap(CPLD_BASE_ADDR, 64);
        if(!cpld_kpd_dev->base) {
                retval = -ENOMEM;
                goto err2;
        }

设置中断触发方式，并注册中断：

        irq = setup_gpio_irq();
        retval = request_irq(irq, cpld_kpd_interrupt, 0, MOD_NAME, MOD_NAME);
        if(retval) {
                pr_debug("CPLDKPD: request_irq(%d) error %d\n",
                                irq, retval);
                goto err3;
        }

2. 中断服务例程，发现中断就报告event：

static irqreturn_t cpld_kpd_interrupt(int irq, void *dev_id)
{
        dprintk("%s.\n", __func__);
        del_timer(&cpld_kpd_dev->poll_timer);
        cpld_kpd_handle_timer(0);
        add_timer(&cpld_kpd_dev->poll_timer);

        return IRQ_RETVAL(1);
}

static void cpld_kpd_handle_timer(unsigned long time)
{

        dprintk("%s.\n", __func__);
        if (key_pad_enabled == 0) {
                dprintk("key pad not enabled\n");
                return;
        }

        if (cpld_kpd_scan_matrix() == 0) {
                dprintk("scan matrix = 0\n");
                return;
        }
}

扫描键盘，看哪个键按下，并发送event，即input_event()函数，报告按下之后要报告一个弹起的事件，因为这里有弹起中断。

static int cpld_kpd_scan_matrix(void)
{
        volatile unsigned short reg;
        int count = 0;

        dprintk("%s.\n", __func__);
        reg = __raw_readw(cpld_kpd_dev->base + KEY_STATUS);

        dprintk("read cpld reg = 0x%x\n", reg);

        if (reg & F1_BITMAP) {
                input_event(cpld_kpd_dev->input, EV_KEY, KEY_F1, 1);
                count++;
                input_event(cpld_kpd_dev->input, EV_KEY, KEY_F1, 0);
        }

        if(reg & F2_BITMAP) {
                input_event(cpld_kpd_dev->input, EV_KEY, KEY_F2, 1);
                count++;
                input_event(cpld_kpd_dev->input, EV_KEY, KEY_F2, 0);
        }

        if(reg & F3_BITMAP) {
                input_event(cpld_kpd_dev->input, EV_KEY, KEY_F3, 1);
                count++;
                input_event(cpld_kpd_dev->input, EV_KEY, KEY_F3, 0);
        }

        if(reg & F4_BITMAP) {
                input_event(cpld_kpd_dev->input, EV_KEY, KEY_F4, 1);
                count++;
                input_event(cpld_kpd_dev->input, EV_KEY, KEY_F4, 0);
        }

        if(reg & HOME_BITMAP) {
                input_event(cpld_kpd_dev->input, EV_KEY, KEY_HOME, 1);
                count++;
                input_event(cpld_kpd_dev->input, EV_KEY, KEY_HOME, 0);
        }

        if(reg & UP_BITMAP) {
                input_event(cpld_kpd_dev->input, EV_KEY, KEY_UP, 1);
                count++;
                input_event(cpld_kpd_dev->input, EV_KEY, KEY_UP, 0);
        }

        if(reg & LEFT_BITMAP) {
                input_event(cpld_kpd_dev->input, EV_KEY, KEY_LEFT, 1);
                count++;
                input_event(cpld_kpd_dev->input, EV_KEY, KEY_LEFT, 0);
        }

        if(reg & RIGHT_BITMAP) {
                input_event(cpld_kpd_dev->input, EV_KEY, KEY_RIGHT, 1);
                count++;
                input_event(cpld_kpd_dev->input, EV_KEY, KEY_RIGHT, 0);
        }

        if(reg & DOWN_BITMAP) {
                input_event(cpld_kpd_dev->input, EV_KEY, KEY_DOWN, 1);
                count++;
                input_event(cpld_kpd_dev->input, EV_KEY, KEY_DOWN, 0);
        }

        if(reg & ENTER_BITMAP) {
                input_event(cpld_kpd_dev->input, EV_KEY, KEY_ENTER, 1);
                count++;
                input_event(cpld_kpd_dev->input, EV_KEY, KEY_ENTER, 0);
        }

        if(reg & ESC_BITMAP) {
                input_event(cpld_kpd_dev->input, EV_KEY, KEY_ESC, 1);
                count++;
                input_event(cpld_kpd_dev->input, EV_KEY, KEY_ESC, 0);
        }

        dprintk("count = 0x%x\n", count);
        return count;
}

具体的按键有如下这些：

static u16 key_mapping[] = {
        KEY_F1, KEY_HOME, KEY_DOWN,
        KEY_F2, KEY_UP, KEY_ENTER,
        KEY_F3, KEY_LEFT, KEY_ESC,
        KEY_F4, KEY_RIGHT, 0
};