精通linux设备驱动程序开发：字符设备 系统cmos 一

《精通linux设备驱动程序开发》第五章-字符设备驱动程序

==================================================================

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

device_create(cmos_class, NULL, MKDEV(MAJOR(cmos_dev_number), i),
                      "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

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/cdev.h>
#include <linux/types.h>
#include <linux/slab.h>//kmalloc()
#include <asm/uaccess.h>//copy_from_user
#include <linux/pci.h>

#define NUM_CMOS_BANKS 2

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

static struct file_operations cmos_fops = {
    .owner = THIS_MODULE, /* Owner *///<linux/fs.h>
#if 0
    .open = cmos_open, /* Open method */
    .release = cmos_release, /* Release method */
    .read = cmos_read, /* Read method */
    .write = cmos_write, /* Write method */
    .llseek = cmos_llseek, /* Seek method */
    .ioctl = cmos_ioctl, /* Ioctl method */
#endif
};

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

#define CMOS_BANK_SIZE (0xFF*8)
#define DEVICE_NAME "ywxcmos"
#define CMOS_BANK0_INDEX_PORT       0x70
#define CMOS_BANK0_DATA_PORT        0x71
#define CMOS_BANK1_INDEX_PORT       0x72
#define CMOS_BANK1_DATA_PORT        0x73


unsigned char addrports[NUM_CMOS_BANKS] = {CMOS_BANK0_INDEX_PORT,
                                           CMOS_BANK1_INDEX_PORT,};
unsigned char dataports[NUM_CMOS_BANKS] = {CMOS_BANK0_DATA_PORT,
                                           CMOS_BANK1_DATA_PORT,};

static int __init cmos_init(void)
{
    int i;
    int ret;
    if(alloc_chrdev_region(&cmos_dev_number, 0,2, DEVICE_NAME) < 0) // register 2 dev
    {
        printk(KERN_DEBUG "Can't register device\n");
        return -1;
    }
    //sys/class/ywxcmos_class/
    cmos_class = class_create(THIS_MODULE, "ywxcmos_class");


    for(i = 0; i < NUM_CMOS_BANKS; i++)
    {
        cmos_devp[i] = kmalloc(sizeof(struct cmos_dev), GFP_KERNEL);
        if (!cmos_devp[i])
        {
            printk("Bad Kmalloc\n");
            return -ENOMEM;
        }

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

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

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

        cmos_devp[i]->bank_number = i;
        cdev_init(&cmos_devp[i]->cdev, &cmos_fops);
        cmos_devp[i]->cdev.owner = THIS_MODULE;
        ret = cdev_add(&cmos_devp[i]->cdev, (cmos_dev_number + i), 1);
        if(ret)
        {
            printk("Bad cdev\n");
            return ret;
        }
    }

    //dev/ywxcmos0 /dev/ywxcmos1
    device_create(cmos_class, NULL, MKDEV(MAJOR(cmos_dev_number), 0),NULL,"ywxcmos0");
    device_create(cmos_class, NULL, MKDEV(MAJOR(cmos_dev_number), 1),NULL,"ywxcmos1");
    printk("ywxCMOS Driver Initialized.\n");
    return 0;
}

/* Driver Exit */
static void __exit cmos_cleanup(void)
{
    int i;

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

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

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

MODULE_LICENSE("GPL");

module_init(cmos_init);
module_exit(cmos_cleanup);

显示测试：

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