基于设备树的led驱动程序

  1 #include <linux/module.h>
  2 #include <linux/kernel.h>
  3 #include <linux/fs.h>
  4 #include <linux/init.h>
  5 #include <linux/delay.h>
  6 #include <asm/io.h>
  7 #include <linux/cdev.h>
  8 #include <linux/device.h>
  9 #include <linux/bitmap.h>
 10 #include <asm/gpio.h>
 11 #include <linux/platform_device.h>
 12 #include <linux/slab.h>
 13 #include <linux/sched.h>
 14 #include <linux/of.h>
 15 
 16 static volatile unsigned long *ledcon;
 17 static volatile unsigned long *leddat;
 18 static struct class *led_class;
 19 static unsigned int pin_th;
 20 dev_t led_dev;
 21 struct cdev *cdev;
 22 
 23 
 24 /* 打开led灯 */
 25 static int led_open(struct inode *inode, struct file *file)
 26 {
 27      *ledcon &= ~(0x3 << (pin_th * 2));
 28      *ledcon |= (0x1 << (pin_th * 2));
 29      *leddat &= ~(1 << pin_th);
 30      return 0;
 31 }
 32 
 33 static struct file_operations led_fops = {
 34                .owner = THIS_MODULE,
 35                .open = led_open,
 36 };
 37 
 38 static int led_probe(struct platform_device *pdev)
 39 {
 40    int pin_info;
 41    int phy_addr;
 42    int io_base;
 43    of_property_read_s32(pdev->dev.of_node, "pin", &pin_info); 
 44    printk("pin_info = 0x%x\n", pin_info);
 45    of_property_read_s32(pdev->dev.of_node, "iobase", &io_base); 
 46    printk("io_base = 0x%x\n", io_base);
 47    pin_th = pin_info & (0xffff);
 48    phy_addr = (io_base | ((pin_info>>16)<<4));
 49    ledcon = ioremap(phy_addr, 2);
 50    leddat = ledcon + 1;
 51    
 52    if (alloc_chrdev_region(&led_dev, MINOR(led_dev), 1, "led"))
 53           return -1;
 54    cdev = cdev_alloc();
 55    if (!cdev)
 56           return -1;
 57    cdev_init(cdev, &led_fops);
 58    cdev_add(cdev, led_dev, 1);
 59 
 60    led_class = class_create(THIS_MODULE, "led");
 61    device_create(led_class,NULL,led_dev,NULL,"led0");   // is /dev/led0
 62 
 63    return 0;
 64    
 65 }
 66 
 67 int led_remove(struct platform_device *pdev)
 68 {
 69     device_destroy(led_class, led_dev);
 70     class_destroy(led_class);
 71     cdev_del(cdev);
 72     unregister_chrdev_region(led_dev, 1);
 73     iounmap(ledcon);
 74     return 0;
 75 }
 76 
 77 static struct of_device_id led_id[] = {
 78               {.compatible = "jz2440_led"},
 79               {},
 80 };
 81 
 82 static struct platform_driver led_drv = {
 83     .probe = led_probe,
 84     .remove = led_remove,   
 85      .driver = {
 86         .name  = "jz2440_led",
 87         .of_match_table = led_id,
 88     },
 89 };
 90 
 91 static int led_init(void)
 92 {
 93     platform_driver_register(&led_drv);
 94     return 0;
 95 }
 96 
 97 static void led_exit(void)
 98 {
 99      platform_driver_unregister(&led_drv);
100 }
101 
102 module_init(led_init);
103 module_exit(led_exit);
104 
105 MODULE_LICENSE("GPL");

以上是驱动程序，下面是设备树dts文件：

 1 #define S3C2440_GPA(_nr)    ((0<<16) + (_nr))
 2 #define S3C2440_GPB(_nr)    ((1<<16) + (_nr))
 3 #define S3C2440_GPC(_nr)    ((2<<16) + (_nr))
 4 #define S3C2440_GPD(_nr)    ((3<<16) + (_nr))
 5 #define S3C2440_GPE(_nr)    ((4<<16) + (_nr))
 6 #define S3C2440_GPF(_nr)    ((5<<16) + (_nr))
 7 #define S3C2440_GPG(_nr)    ((6<<16) + (_nr))
 8 #define S3C2440_GPH(_nr)    ((7<<16) + (_nr))
 9 #define S3C2440_GPJ(_nr)    ((8<<16) + (_nr))
10 #define S3C2440_GPK(_nr)    ((9<<16) + (_nr))
11 #define S3C2440_GPL(_nr)    ((10<<16) + (_nr))
12 #define S3C2440_GPM(_nr)    ((11<<16) + (_nr))
13  
14 /dts-v1/;
15 
16 / {
17     model = "SMDK2440";
18     compatible = "samsung,smdk2440";
19 
20     #address-cells = <1>;
21     #size-cells = <1>;
22         
23     memory@30000000 {
24         device_type = "memory";
25         reg =  <0x30000000 0x4000000>;
26     };
  
34     chosen {
35         bootargs = "noinitrd root=/dev/mtdblock4 rw init=/linuxrc console=ttySAC0,115200";
36     };
37 
38     
39     led {
40         compatible = "jz2440_led";
41         pin = <S3C2440_GPF(5)>;
42         iobase = <0x56000000>;
43     };
44 };