基于设备树的led驱动程序

 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/fs.h>
 #include <linux/init.h>
 #include <linux/delay.h>
 #include <asm/io.h>
 #include <linux/cdev.h>
 #include <linux/device.h>
 #include <linux/bitmap.h>
 #include <asm/gpio.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
 #include <linux/of.h>

 static volatile unsigned long *ledcon;
 static volatile unsigned long *leddat;
 static struct class *led_class;
 static unsigned int pin_th;
 dev_t led_dev;
 struct cdev *cdev;

 /* 打开led灯 */
 static int led_open(struct inode *inode, struct file *file)
 {
      *ledcon &= ~(0x3 << (pin_th * ));
      *ledcon |= (0x1 << (pin_th * ));
      *leddat &= ~( << pin_th);
      return ;
 }

 static struct file_operations led_fops = {
                .owner = THIS_MODULE,
                .open = led_open,
 };

 static int led_probe(struct platform_device *pdev)
 {
    int pin_info;
    int phy_addr;
    int io_base;
    of_property_read_s32(pdev->dev.of_node, "pin", &pin_info);
    printk("pin_info = 0x%x\n", pin_info);
    of_property_read_s32(pdev->dev.of_node, "iobase", &io_base);
    printk("io_base = 0x%x\n", io_base);
    pin_th = pin_info & (0xffff);
    phy_addr = (io_base | ((pin_info>>)<<));
    ledcon = ioremap(phy_addr, );
    leddat = ledcon + ;

    if (alloc_chrdev_region(&led_dev, MINOR(led_dev), , "led"))
           return -;
    cdev = cdev_alloc();
    if (!cdev)
           return -;
    cdev_init(cdev, &led_fops);
    cdev_add(cdev, led_dev, );

    led_class = class_create(THIS_MODULE, "led");
    device_create(led_class,NULL,led_dev,NULL,"led0");   // is /dev/led0

    return ;

 }

 int led_remove(struct platform_device *pdev)
 {
     device_destroy(led_class, led_dev);
     class_destroy(led_class);
     cdev_del(cdev);
     unregister_chrdev_region(led_dev, );
     iounmap(ledcon);
     return ;
 }

 static struct of_device_id led_id[] = {
               {.compatible = "jz2440_led"},
               {},
 };

 static struct platform_driver led_drv = {
     .probe = led_probe,
     .remove = led_remove,
      .driver = {
         .name  = "jz2440_led",
         .of_match_table = led_id,
     },
 };

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

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

 module_init(led_init);
 module_exit(led_exit);

 MODULE_LICENSE("GPL");

以上是驱动程序，下面是设备树dts文件：

 #define S3C2440_GPA(_nr)    ((0<<16) + (_nr))
 #define S3C2440_GPB(_nr)    ((1<<16) + (_nr))
 #define S3C2440_GPC(_nr)    ((2<<16) + (_nr))
 #define S3C2440_GPD(_nr)    ((3<<16) + (_nr))
 #define S3C2440_GPE(_nr)    ((4<<16) + (_nr))
 #define S3C2440_GPF(_nr)    ((5<<16) + (_nr))
 #define S3C2440_GPG(_nr)    ((6<<16) + (_nr))
 #define S3C2440_GPH(_nr)    ((7<<16) + (_nr))
 #define S3C2440_GPJ(_nr)    ((8<<16) + (_nr))
 #define S3C2440_GPK(_nr)    ((9<<16) + (_nr))
 #define S3C2440_GPL(_nr)    ((10<<16) + (_nr))
 #define S3C2440_GPM(_nr)    ((11<<16) + (_nr))

 /dts-v1/;

 / {
     model = "SMDK2440";
     compatible = "samsung,smdk2440";

     #address-cells = <>;
     #size-cells = <>;

     memory@ {
         device_type = "memory";
         reg =  <0x30000000 0x4000000>;
     };
 
     chosen {
         bootargs = "noinitrd root=/dev/mtdblock4 rw init=/linuxrc console=ttySAC0,115200";
     };

     led {
         compatible = "jz2440_led";
         pin = <S3C2440_GPF()>;
         iobase = <0x56000000>;
     };
 };