第一课:linux设备树的引入与体验(基于linux4.19内核版本)

static struct file_operations myled_oprs = {
	.owner = THIS_MODULE, //表示这个模块本身
	.open  = led_open,
	.write = led_write,
	.release = led_release,
};

static int myled_init(void)
{
	major = register_chrdev(0, "myled", &myled_oprs);

	return 0;
}

static void myled_exit(void)
{
	unregister_chrdev(major, "myled");
}

module_init(myled_init);
module_exit(myled_exit);

MODULE_LICENSE("GPL");

static unsigned int gpio_base[] = {
	0x56000000, /* GPACON */
	0x56000010, /* GPBCON */
	0x56000020, /* GPCCON */
	0x56000030, /* GPDCON */
	0x56000040, /* GPECON */
	0x56000050, /* GPFCON */
	0x56000060, /* GPGCON */
	0x56000070, /* GPHCON */
	0,          /* GPICON */
	0x560000D0, /* GPJCON */
};

#define S3C2440_GPA(n)  (0<<16 | n)
#define S3C2440_GPB(n)  (1<<16 | n)
#define S3C2440_GPC(n)  (2<<16 | n)
#define S3C2440_GPD(n)  (3<<16 | n)
#define S3C2440_GPE(n)  (4<<16 | n)
#define S3C2440_GPF(n)  (5<<16 | n)
#define S3C2440_GPG(n)  (6<<16 | n)
#define S3C2440_GPH(n)  (7<<16 | n)
#define S3C2440_GPI(n)  (8<<16 | n)
#define S3C2440_GPJ(n)  (9<<16 | n)

static int led_open (struct inode *node, struct file *filp)
{
	/* 把LED引脚配置为输出引脚 */
	/* GPF5 - 0x56000050 */
	int bank = led_pin >> 16;
	int base = gpio_base[bank];

	int pin = led_pin & 0xffff;
	gpio_con = ioremap(base, 8);  
	if (gpio_con) {
		printk("ioremap(0x%x) = 0x%x\n", base, gpio_con);
	}
	else {
		return -EINVAL;
	}
	
	gpio_dat = gpio_con + 1;

	*gpio_con &= ~(3<<(pin * 2));
	*gpio_con |= (1<<(pin * 2));  

	return 0;
}

static ssize_t led_write (struct file *filp, const char __user *buf, size_t size, loff_t *off)
{
	/* 根据APP传入的值来设置LED引脚 */
	unsigned char val;
	int pin = led_pin & 0xffff;
	
	copy_from_user(&val, buf, 1);

	if (val)
	{
		/* 点灯 */
		*gpio_dat &= ~(1<<pin);
	}
	else
	{
		/* 灭灯 */
		*gpio_dat |= (1<<pin);
	}

	return 1; /* 已写入1个数据 */
}

static int myled_init(void)
{
	major = register_chrdev(0, "myled", &myled_oprs);

	led_class = class_create(THIS_MODULE, "myled");
	device_create(led_class, NULL, MKDEV(major, 0), NULL, "led"); /* /dev/led */

	return 0;
}

static void myled_exit(void)
{
	unregister_chrdev(major, "myled");
	device_destroy(led_class,  MKDEV(major, 0));
	class_destroy(led_class);
}

static int led_release (struct inode *node, struct file *filp)
{
	printk("iounmap(0x%x)\n", gpio_con);
	iounmap(gpio_con);
	return 0;
}

    struct platform_device {
	const char	*name;
	int		id;
	bool		id_auto;
	struct device	dev;
	u32		num_resources;
	/*resource 里面确定使用那些资源*/
	struct resource	*resource;

	const struct platform_device_id	*id_entry;
	char *driver_override; /* Driver name to force a match */

	/* MFD cell pointer */
	struct mfd_cell *mfd_cell;

	/* arch specific additions */
	struct pdev_archdata	archdata;
	};

    struct platform_driver {
    	int (*probe)(struct platform_device *);
    	int (*remove)(struct platform_device *);
    	void (*shutdown)(struct platform_device *);
    	int (*suspend)(struct platform_device *, pm_message_t state);
    	int (*resume)(struct platform_device *);
    	struct device_driver driver;
    	const struct platform_device_id *id_table;
    	bool prevent_deferred_probe;
    };

    struct bus_type platform_bus_type = {
    	.name		= "platform",
    	.dev_groups	= platform_dev_groups,
    	.match		= platform_match,
    	.uevent		= platform_uevent,
    	.pm		= &platform_dev_pm_ops,
    };

static int platform_match(struct device *dev, struct device_driver *drv)
{		
	/*省略部分无用代码*/
	/* Then try to match against the id table */
	if (pdrv->id_table)
		return platform_match_id(pdrv->id_table, pdev) != NULL;

	/* fall-back to driver name match */
	return (strcmp(pdev->name, drv->name) == 0);
}

/* 分配/设置/注册一个platform_device */
/*设置资源*/
static struct resource led_resource[] = {
    [0] = {
		/*指明了使用那个引脚*/
        .start = S3C2440_GPF(5),
		/*end并不重要，可以随意指定*/
        .end   = S3C2440_GPF(5),
        .flags = IORESOURCE_MEM,
    },
};

static void led_release(struct device * dev)
{
}


static struct platform_device led_dev = {
    .name         = "myled",
    .id       = -1,
    .num_resources    = ARRAY_SIZE(led_resource),
    .resource     = led_resource,
    .dev = { 
    	.release = led_release, 
	},
};

/*入口函数去注册平台设备*/
static int led_dev_init(void)
{
	platform_device_register(&led_dev);
	return 0;
}
/*出口函数去释放这个平台设备*/
static void led_dev_exit(void)
{
	platform_device_unregister(&led_dev);
}

module_init(led_dev_init);
module_exit(led_dev_exit);

static int led_probe(struct platform_device *pdev)
{
	struct resource		*res;

	/* 根据platform_device的资源进行ioremap */
	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	led_pin = res->start;

	major = register_chrdev(0, "myled", &myled_oprs);

	led_class = class_create(THIS_MODULE, "myled");
	device_create(led_class, NULL, MKDEV(major, 0), NULL, "led"); /* /dev/led */
	
	return 0;
}


struct platform_driver led_drv = {
	.probe		= led_probe,
	.remove		= led_remove,
	.driver		= {
		.name	= "myled",
	}
};


static int myled_init(void)
{
	platform_driver_register(&led_drv);
	return 0;
}

static void myled_exit(void)
{
	platform_driver_unregister(&led_drv);
}

KERN_DIR = /work/system/linux-4.19-rc3

all:
	make -C $(KERN_DIR) M=`pwd` modules 

clean:
	make -C $(KERN_DIR) M=`pwd` modules clean
	rm -rf modules.order

obj-m	+= led_drv.o
obj-m	+= led_dev.o

static struct resource led_resource[] = {
    [0] = {
        .start = S3C2440_GPF(6),
        .end   = S3C2440_GPF(6),
        .flags = IORESOURCE_MEM,
    },
};

    	led {
    		compatible = "jz2440_led";
    		reg = <S3C2410_GPF(5) 1>;
    	};

	/* Attempt an OF style match first */
	if (of_driver_match_device(dev, drv))
		return 1;

/**
 * of_driver_match_device - Tell if a driver's of_match_table matches a device.
 * @drv: the device_driver structure to test
 * @dev: the device structure to match against
 */
static inline int of_driver_match_device(struct device *dev,
					 const struct device_driver *drv)
{
	return of_match_device(drv->of_match_table, dev) != NULL;
}

/*
 * Struct used for matching a device
 */
struct of_device_id {
	char	name[32];
	char	type[32];
	char	compatible[128];
	const void *data;
};

static const struct of_device_id of_match_leds[] = {
	{ .compatible = "jz2440_led", .data = NULL },
	{ /* sentinel */ }
};

struct platform_driver led_drv = {
	.probe		= led_probe,
	.remove		= led_remove,
	.driver		= {
		.name	= "myled",
		.of_match_table = of_match_leds, /* 能支持哪些来自于dts的platform_device */
	}
};

    	led {
    		compatible = "jz2440_led";
    		reg = <S3C2410_GPF(6) 1>;
    	};

	led {
		compatible = "jz2440_led";
		pin = <S3C2410_GPF(5)>;
	};

static int led_probe(struct platform_device *pdev)
{
	struct resource		*res;

	/* 根据platform_device的资源进行ioremap */
	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (res) {
		led_pin = res->start;
	}
	else {
		/* 获得pin属性 */
		of_property_read_s32(pdev->dev.of_node, "pin", &led_pin);
	}

	if (!led_pin) 
	{
		printk("can not get pin for led\n");
		return -EINVAL;
	}
		

	major = register_chrdev(0, "myled", &myled_oprs);

	led_class = class_create(THIS_MODULE, "myled");
	device_create(led_class, NULL, MKDEV(major, 0), NULL, "led"); /* /dev/led */
	
	return 0;
}

	/* 根据platform_device的资源进行ioremap */
	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (res) {
		led_pin = res->start;
	}
	else {
		/* 获得pin属性 */
		of_property_read_s32(pdev->dev.of_node, "pin", &led_pin);
	}

	if (!led_pin) 
	{
		printk("can not get pin for led\n");
		return -EINVAL;
	}

 SAMSUNG Exynos SoCs Chipid driver.
 Required properties:（必须填写的内容）
 - compatible : Should at least contain "samsung,exynos4210-chipid".
 - reg: offset and length of the register set
 Example:
	chipid@10000000 {
		compatible = "samsung,exynos4210-chipid";
		reg = <0x10000000 0x100>;
	};