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>;

     };

 };