基於Dragonboard 410c的音樂儲錢罐（二）

音樂儲錢罐是利用紅外傳感器來判斷硬幣的投入的，音樂的播放我們可以直接利用android自帶的音樂播放器，該播放器只要接收到相關的鍵值，就可以自動進行播放音樂和切換歌曲，因此，我們可以在IR的驅動中直接利用Input子系統進行上報相關鍵值。

我們先來看看IR的介紹

可以看到這款IR需要3.3-5v供電，因此我們可以把VCC引腳接到Dragonboard410c板上的 Low Speed Expansion Connector(J8)第37腳，GND引腳接到第1腳就可以了。

紅外傳感器判斷到有硬幣投入存錢罐時，就會輸出信號，可以把這個信號配置成中斷信號，我們直接利用Dragonboard410c預留的ALPS_INT腳來連接out引腳。

OK，硬件連接已經確定，我們在配置一下DT就可以了。

下面再附上IR的驅動代碼

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/sysfs.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/input.h>
#include <linux/jiffies.h>
#include <linux/irq.h>
#include <linux/of_gpio.h>

struct ir_data {
    int gpio;
    int irq;
    struct input_dev *input;
    struct delayed_work report_work;
};

static irqreturn_t ir_interrupt_handler(int irq, void *ptr) {
    struct ir_data* data = (struct ir_data*)ptr;

    if (!data) {
        printk("%s: data is NULL!\n", __func__);
        return IRQ_HANDLED;
    }

    schedule_delayed_work(&data->report_work, 0);

    return IRQ_HANDLED;
}

static void report_work_func(struct work_struct *work) {
    struct ir_data *obj = (struct ir_data *)container_of(work, struct ir_data, report_work.work);
    static unsigned long last_time = 0;
    unsigned long after_time;
    unsigned long tmp;

    after_time = jiffies;
    tmp = (after_time - last_time) * 1000 / HZ;

    if (tmp > 50) {
        if (!gpio_get_value(obj->gpio)) {
            input_report_key(obj->input, KEY_NEXTSONG, 1);
            input_sync(obj->input);
            input_report_key(obj->input, KEY_NEXTSONG, 0);
            input_sync(obj->input);
        }
    }
    last_time = after_time;
}

static int parse_dt(struct platform_device* pdev, struct ir_data* data) {
    int rc;
    struct device_node* node = pdev->dev.of_node;

    data->gpio = of_get_named_gpio(node,"thunder,gpio", 0);
    if (gpio_is_valid(data->gpio)) {
        rc = gpio_request(data->gpio, "ir_gpio");
        if (rc < 0) {
            printk("%s: unable to request gpio\n", __func__);
            return -EINVAL;
        }
        rc = gpio_direction_input(data->gpio);
    }

    if (data->gpio < 0) {
        printk("%s: error gpio\n", __func__);
        return -EINVAL;
    }

    return 0;
}

static ssize_t ir_show_value(struct device *dev, struct device_attribute* attr, char* buf) {
    struct ir_data *data = dev_get_drvdata(dev);

    printk("%s: gpio value is %d\n", __func__, gpio_get_value(data->gpio));
    return 0;
}

static DEVICE_ATTR(value, 0644, ir_show_value, NULL);

static int ir_probe(struct platform_device *pdev) {
    struct ir_data* data;
    int result;

    printk("%s\n", __func__);
    data = kmalloc(sizeof(struct ir_data), GFP_KERNEL);
    if (!data) {
        printk("%s kmalloc error\n", __func__);
        return -ENOMEM;  
    }
    dev_set_drvdata(&pdev->dev, data);

    data->input = input_allocate_device();
    if (!data->input) {
        printk("%s: input_allocate_device failed!\n", __func__);
        goto err_input_allocate;
    }
    data->input->name = "ir";

    set_bit(EV_SYN, data->input->evbit);
    set_bit(EV_KEY, data->input->evbit);
    set_bit(KEY_NEXTSONG, data->input->keybit);

    result = input_register_device(data->input);
    if (result < 0) {
        printk("%s: input_register_device() failed!\n", __func__);
        goto err_input_register;
    }

    result = parse_dt(pdev, data);
    if (result < 0) {
        printk("%s:error when parse dt\n", __func__);
        result = -EINVAL;
        goto err_parse_dt;
    }

    data->irq = gpio_to_irq(data->gpio);

    result = request_irq(data->irq, ir_interrupt_handler, IRQF_TRIGGER_FALLING, "ir_int", data);
    if (result < 0) {
        printk("%s: Unable to request irq\n", __func__);
        goto err_parse_dt;
    }
    printk("%s: gpio=%d, irq=%d\n", __func__, data->gpio, data->irq);

    INIT_DELAYED_WORK(&data->report_work, report_work_func);

    result = sysfs_create_file(&pdev->dev.kobj, &dev_attr_value.attr);
    printk("%s: ir probe success\n", __func__);
    return 0;

err_parse_dt:
err_input_register:
    input_free_device(data->input);
err_input_allocate:
    kfree(data);
    printk("%s: ir probe failed\n", __func__);
    return result;
}

static int ir_remove(struct platform_device *pdev){
    return 0;
}

static struct of_device_id ir_match_table[] = {
    { .compatible = "thundersoft,ir",},
    { },
};

static struct platform_driver ir_driver = {
    .probe  = ir_probe,
    .remove = ir_remove,
    .driver = {
        .owner = THIS_MODULE,
        .name = "ir_module",
        .of_match_table = ir_match_table,
    },
};

module_platform_driver(ir_driver);
MODULE_AUTHOR("Chen Guangxiang([email protected])");
MODULE_LICENSE("GPL v2");