设备树——按键中断

在arch/arm/boot/dts/Makefile中指定要编译的设备树文件

dtb-$(CONFIG_ARCH_S3C2440) += jz2440.dtb jz2440_irq.dtb

转载设备树常用函数

linux-4.19-rc3\Documentation\devicetree\bindings\interrupt-controller\samsung,s3c24xx-irq.txt
linux-4.19-rc3\Documentation\devicetree\bindings\pinctrl\samsung-pinctrl.txt
＃interrupt-cells：指定编码所需的单元数
中断源。 值应为4，中断描述符应为
具有以下格式：

ctrl_num：包含要使用的控制器：
- 0 …主控制器
- 1 …副控制器
- 2 … s3c2416和s3c2450上的第二个主控制器
parent_irq：包含主控制器中的父位，在主控制器中将被忽略为0
ctrl_irq：包含控制器的中断位
type：包含要使用的触发器类型
- 1 = rising edge triggered
- 2 = falling edge triggered
- 3 = rising and falling edge triggered
- 4 = high level triggered
- 8 = low level triggered

jz2440_irq.dts中添加

buttons {
        compatible = "jz2440_button";
		eint-pins  = <&gpf 0 0>, <&gpf 2 0>, <&gpg 3 0>, <&gpg 11 0>;
        interrupts-extended = <&intc 0 0 0 3>,//中断扩展属性
                              <&intc 0 0 2 3>,//主控制器*直接发给主中断控制器为0*eint2*双边沿触发
                              <&gpg 3 3>,//eint11-gpg3
                              <&gpg 11 3>;
    };

设备节点将转换为platform_device中的resource

• resource
  • MEM:来自设备节点的reg
  • IRQ：中断号，来自中断属性

#include 
#include 
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#include 
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#include 

#include 
#include 
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#include 

static struct class *sixthdrv_class;
static struct device	*sixthdrv_class_dev;

volatile unsigned long *gpfcon;
volatile unsigned long *gpfdat;
volatile unsigned long *gpgcon;
volatile unsigned long *gpgdat;

static struct timer_list buttons_timer;

static DECLARE_WAIT_QUEUE_HEAD(button_waitq);

/* 中断事件标志, 中断服务程序将它置1，sixth_drv_read将它清0 */
static volatile int ev_press = 0;

struct pin_desc{
	unsigned int pin;
	unsigned int key_val;
	int irq;
};

struct pin_desc pins_desc[4] = {{0, 0x01},{0, 0x02},{0, 0x03},{0, 0x04},};


/* 键值: 按下时, 0x01, 0x02, 0x03, 0x04 */
/* 键值: 松开时, 0x81, 0x82, 0x83, 0x84 */
static unsigned char key_val;
static struct pin_desc *irq_pd;

/* 确定按键值 */
static irqreturn_t buttons_irq(int irq, void *dev_id)
{
	/* 10ms后启动定时器 */
	irq_pd = (struct pin_desc *)dev_id;
	mod_timer(&buttons_timer, jiffies+HZ/100);
	return IRQ_RETVAL(IRQ_HANDLED);
}

static int sixth_drv_open(struct inode *inode, struct file *file)
{
	int ret;

	/* 配置GPF0,2为输入引脚  配置GPG3,11为输入引脚 */
	ret = request_irq(pins_desc[0].irq,  buttons_irq, 0, "S2", &pins_desc[0]);
	if (ret) {
		printk("reqeust_irq %d for EINT0 err : %d!\n", pins_desc[0].irq, ret);
	}
	
	ret = request_irq(pins_desc[1].irq,  buttons_irq, 0, "S3", &pins_desc[1]);
	if (ret) {
		printk("reqeust_irq for EINT2 err : %d!\n", ret);
	}

	ret = request_irq(pins_desc[2].irq, buttons_irq, 0, "S4", &pins_desc[2]);
	if (ret) {
		printk("reqeust_irq for EINT11 err : %d!\n", ret);
	}

	ret = request_irq(pins_desc[3].irq, buttons_irq, 0, "S5", &pins_desc[3]);	
	if (ret) {
		printk("reqeust_irq for EINT19 err : %d!\n", ret);
	}
	
	return 0;
}

ssize_t sixth_drv_read(struct file *file, char __user *buf, size_t size, loff_t *ppos)
{
		/* 如果没有按键动作, 休眠 */
	wait_event_interruptible(button_waitq, ev_press);

	/* 如果有按键动作, 返回键值 */
	copy_to_user(buf, &key_val, 1);
	ev_press = 0;
	
	return 1;
}


int sixth_drv_close(struct inode *inode, struct file *file)
{
	int i;
	for (i = 0; i < sizeof(pins_desc)/sizeof(pins_desc[0]); i++) {
		free_irq(pins_desc[i].irq, &pins_desc[i]);
	}
	return 0;
}

static struct file_operations sixth_drv_fops = {
    .owner   =  THIS_MODULE,    /* 这是一个宏，推向编译模块时自动创建的__this_module变量 */
    .open    =  sixth_drv_open,     
	.read	 =	sixth_drv_read,	   
	.release =  sixth_drv_close,
};

int major;
static void buttons_timer_function(struct timer_list *t)
{
	struct pin_desc * pindesc = irq_pd;
	unsigned int pinval;

	if (!pindesc)
		return;
		
	pinval = gpio_get_value(pindesc->pin);
	if (pinval)
	{	/* 松开 */
		key_val = 0x80 | pindesc->key_val;
	}
	else
	{	/* 按下 */
		key_val = pindesc->key_val;
	}

    ev_press = 1;                  /* 表示中断发生了 */
    wake_up_interruptible(&button_waitq);   /* 唤醒休眠的进程 */
}

static int sixth_drv_init(void)
{
	timer_setup(&buttons_timer, buttons_timer_function, 0);
	add_timer(&buttons_timer); 

	major = register_chrdev(0, "sixth_drv",&sixth_drv_fops);
	sixthdrv_class = class_create(THIS_MODULE, "sixth_drv");

	/* 为了让mdev根据这些信息来创建设备节点 */
	sixthdrv_class_dev = device_create(sixthdrv_class, NULL, MKDEV(major, 0), NULL, "buttons"); /* /dev/buttons */

	gpfcon = (volatile unsigned long *)ioremap(0x56000050, 16);
	gpfdat = gpfcon + 1;
	gpgcon = (volatile unsigned long *)ioremap(0x56000060, 16);
	gpgdat = gpgcon + 1;

	return 0;
}

static void sixth_drv_exit(void)
{
	del_timer(&buttons_timer); 
	unregister_chrdev(major, "sixth_drv");
	device_destroy(sixthdrv_class, MKDEV(major, 0));
	class_destroy(sixthdrv_class);
	iounmap(gpfcon);
	iounmap(gpgcon);
}

static int buttons_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;		
	struct device_node *dp_node = dev->of_node;
	struct resource		*res;
	int i;

	for (i = 0; i < sizeof(pins_desc)/sizeof(pins_desc[0]); i++)
	{
		/* 根据platform_device的资源进行获得中断号,触发类型 */
		res = platform_get_resource(pdev, IORESOURCE_IRQ, i);
		if (res) {
			pins_desc[i].irq  = res->start;
			printk("get irq %d\n", pins_desc[i].irq);
		}
		else {
			printk("can not get irq res for eint0\n");
			return -1;
		}
		pins_desc[i].pin = of_get_named_gpio(dp_node, "eint-pins", i);
		printk("pins_desc[%d].pin = %d\n", i, pins_desc[i].pin);
	}

	return sixth_drv_init();
}
static int buttons_remove(struct platform_device *pdev)
{
	sixth_drv_exit();
	return 0;
}

static const struct of_device_id of_match_buttons[] = {
	{ .compatible = "jz2440_button", .data = NULL },
	{ /* sentinel */ }
};

struct platform_driver buttons_drv = {
	.probe		= buttons_probe,
	.remove		= buttons_remove,
	.driver		= {
		.name	= "mybuttons",
		.of_match_table = of_match_buttons, /* 能支持哪些来自于dts的platform_device */
	}
};

static int buttons_init(void)
{
	platform_driver_register(&buttons_drv);
	return 0;
}

static void buttons_exit(void)
{
	platform_driver_unregister(&buttons_drv);
}

module_init(buttons_init);
module_exit(buttons_exit);
MODULE_LICENSE("GPL");