精通linux设备驱动程序开发：字符设备 系统cmos 一

4768阅读　0评论2012-01-03　yuweixian4230
分类：LINUX

《精通linux设备驱动程序开发》第五章-字符设备驱动程序

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注意：在官网源程序中，在/dev/下建立 设备节点，这句话有问题，导致
  1. device_create(cmos_class, NULL, MKDEV(MAJOR(cmos_dev_number), i),
  2.                       "cmos%d", i);
我在建立节点的时候，只能建立 /dev/cmos0 而不能建立/dev/cmos1

这里附上修改过的源码附件： cmos.rar   将rar修改为tar.bz2
  1. #include <linux/init.h>
  2. #include <linux/kernel.h>
  3. #include <linux/module.h>
  4. #include <linux/fs.h>
  5. #include <linux/cdev.h>
  6. #include <linux/types.h>
  7. #include <linux/slab.h>//kmalloc()
  8. #include <asm/uaccess.h>//copy_from_user
  9. #include <linux/pci.h>

  11. #define NUM_CMOS_BANKS 2

  13. /* Per-device (per-bank) structure */
  14. struct cmos_dev {
  15.     unsigned short current_pointer; /* Current pointer within the
  16.          bank */
  17.     unsigned int size; /* Size of the bank */
  18.     int bank_number; /* CMOS bank number */
  19.     struct cdev cdev; /* The cdev structure */
  20.     char name[10]; /* Name of I/O region */
  21.     /* ... */ /* Mutexes, spinlocks, wait
  22.          queues, .. */
  23. };
  24. struct cmos_dev *cmos_devp[NUM_CMOS_BANKS];

  26. static struct file_operations cmos_fops = {
  27.     .owner = THIS_MODULE, /* Owner *///<linux/fs.h>
  28. #if 0
  29.     .open = cmos_open, /* Open method */
  30.     .release = cmos_release, /* Release method */
  31.     .read = cmos_read, /* Read method */
  32.     .write = cmos_write, /* Write method */
  33.     .llseek = cmos_llseek, /* Seek method */
  34.     .ioctl = cmos_ioctl, /* Ioctl method */
  35. #endif
  36. };

  38. static dev_t cmos_dev_number; /* Allotted device number */
  39. struct class *cmos_class; /* Tie with the device model */

  41. #define CMOS_BANK_SIZE (0xFF*8)
  42. #define DEVICE_NAME "ywxcmos"
  43. #define CMOS_BANK0_INDEX_PORT 0x70
  44. #define CMOS_BANK0_DATA_PORT 0x71
  45. #define CMOS_BANK1_INDEX_PORT 0x72
  46. #define CMOS_BANK1_DATA_PORT 0x73


  49. unsigned char addrports[NUM_CMOS_BANKS] = {CMOS_BANK0_INDEX_PORT,
  50.                                            CMOS_BANK1_INDEX_PORT,};
  51. unsigned char dataports[NUM_CMOS_BANKS] = {CMOS_BANK0_DATA_PORT,
  52.                                            CMOS_BANK1_DATA_PORT,};

  54. static int __init cmos_init(void)
  55. {
  56.     int i;
  57.     int ret;
  58.     if(alloc_chrdev_region(&cmos_dev_number, 0,2, DEVICE_NAME) < 0) // register 2 dev
  59.     {
  60.         printk(KERN_DEBUG "Can't register device\n");
  61.         return -1;
  62.     }
  63.     //sys/class/ywxcmos_class/
  64.     cmos_class = class_create(THIS_MODULE, "ywxcmos_class");

  66.          
  67.     for(i = 0; i < NUM_CMOS_BANKS; i++)
  68.     {    
  69.         cmos_devp[i] = kmalloc(sizeof(struct cmos_dev), GFP_KERNEL);
  70.         if (!cmos_devp[i])
  71.         {
  72.             printk("Bad Kmalloc\n");
  73.             return -ENOMEM;
  74.         }

  76.         sprintf(cmos_devp[i]->name, "ywxcmos%d", i);

  78.         //proc/ioports cmoso cmos1
  79.         release_region(addrports[i], 2);////////add me

  81.         if(!(request_region(addrports[i], 2, cmos_devp[i]->name)))
  82.         {
  83.             printk("ywxcmos: I/O port 0x%x is not free.\n", addrports[i]);
  84.             return -EIO;
  85.         }

  87.         cmos_devp[i]->bank_number = i;
  88.         cdev_init(&cmos_devp[i]->cdev, &cmos_fops);
  89.         cmos_devp[i]->cdev.owner = THIS_MODULE;
  90.         ret = cdev_add(&cmos_devp[i]->cdev, (cmos_dev_number + i), 1);
  91.         if(ret)
  92.         {
  93.             printk("Bad cdev\n");
  94.             return ret;
  95.         }
  96.     }
  97.     
  98.     //dev/ywxcmos0 /dev/ywxcmos1
  99.     device_create(cmos_class, NULL, MKDEV(MAJOR(cmos_dev_number), 0),NULL,"ywxcmos0");
  100.     device_create(cmos_class, NULL, MKDEV(MAJOR(cmos_dev_number), 1),NULL,"ywxcmos1");
  101.     printk("ywxCMOS Driver Initialized.\n");
  102.     return 0;
  103. }

  105. /* Driver Exit */
  106. static void __exit cmos_cleanup(void)
  107. {
  108.     int i;

  110.     printk("exit starting...\n");
  111.     /* Release the major number */
  112.     unregister_chrdev_region((cmos_dev_number), NUM_CMOS_BANKS);

  114.     /* Release I/O region */
  115.     for(i=0; i<NUM_CMOS_BANKS; i++)
  116.     {
  117.         device_destroy (cmos_class, MKDEV(MAJOR(cmos_dev_number), i));
  118.         release_region(addrports[i], 2);
  119.         cdev_del(&cmos_devp[i]->cdev);
  120.         kfree(cmos_devp[i]);
  121.     }

  123.     /* Destroy cmos_class */
  124.     class_destroy(cmos_class);
  125.     printk("exit finished..\n");
  126. }

  128. MODULE_LICENSE("GPL");

  130. module_init(cmos_init);
  131. module_exit(cmos_cleanup);

显示测试：
  1. ywx@ywx:~/Desktop/module/jingtong/cmos$ sudo insmod ./cmos.ko
  2. ywx@ywx:~/Desktop/module/jingtong/cmos$ ls /dev/ywxcmos*
  3. /dev/ywxcmos0 /dev/ywxcmos1  在/dev/下新建了设备节点
  4. ywx@ywx:~/Desktop/module/jingtong/cmos$ cat /proc/devices | grep ywx
  5. 250 ywxcmos 这是动态分配的主设备号
  6. ywx@ywx:~/Desktop/module/jingtong/cmos$ ls /sys/class/ywxcmos_class/
  7. ywxcmos0 ywxcmos1在/sys/class/下新建了 ywxcmos_class 设备类
  8. ywx@ywx:~/Desktop/module/jingtong/cmos$ grep cmos /proc/ioports
  9.   0070-0071 : ywxcmos0  io分配的内存 request_region
  10.   0072-0073 : ywxcmos1
  11. ywx@ywx:~/Desktop/module/jingtong/cmos$ sudo rmmod cmos
  12. ywx@ywx:~/Desktop/module/jingtong/cmos$ dmesg | tail -5
  13. [ 521.275943] [<c0217d85>] ? sys_close+0x75/0xc0
  14. [ 521.275947] [<c05cc204>] syscall_call+0x7/0xb
  15. [ 521.282050] ywxCMOS Driver Initialized.
  16. [ 610.405604] exit starting...
  17. [ 610.410214] exit finished..

==================================================================
参考资料：
精通linux设备驱动程序开发 笔记之九
http://blog.zhengrui.info/2008/06/u0026quotessential-linux-device-driveru0026quot-nine-notes/
精通linux设备驱动程序开发官网
   listing05.1.html



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