driver dev

maytures

hello driver 显示/dev/下一个结点，动态申请设备号
#include      //dev_t
#include       //struct cdev
#include         //alloc_chrdev_region()
#include     //class_create()
dev_t                  devid;
static struct cdev     *maytures_cdev;
static int             maytures_Major = 0;
static int             maytures_Minor = 0;
static struct class    *maytures_class;
static struct file_operations maytures_fops = {
    .owner        = THIS_MODULE,
};
static int __init maytures_init(void)
{
    int err;
    //初始化cdev
    maytures_cdev        = cdev_alloc();
    cdev_init(maytures_cdev, &maytures_fops);
    maytures_cdev->owner = THIS_MODULE;
    //动态获取主设备号(dev_t devid中包含"主设备号"和"次设备号"信息)
    alloc_chrdev_region(&devid, 66, 1, "maytures");
    maytures_Major = MAJOR(devid);
    maytures_Minor = MINOR(devid);
    printk(KERN_ALERT "I was assigned major number %d.\n", maytures_Major);
    printk(KERN_ALERT "I was assigned minor number %d.\n", maytures_Minor);
    //注册字符设备 (1)
    err = cdev_add(maytures_cdev, devid, 1);
    if (err) {
        printk(KERN_NOTICE "Error %d adding device\n", err);
        return -1;
    }
// WM8350_SW_RESET_CHIP_ID_MASK = 0x0;
    maytures_class = class_create(THIS_MODULE, "maytures_class1");
    if (IS_ERR(maytures_class)) {
        printk(KERN_ALERT "create class error\n");
        return -1;
    }
    device_create(maytures_class, NULL, devid, NULL, "maytures" "%d", MINOR(devid));   
    return 0;
}
static void __exit maytures_exit(void)
{
    unregister_chrdev_region(devid, 1);
    cdev_del(maytures_cdev);
    device_destroy(maytures_class, devid);
    class_destroy(maytures_class);
printk(KERN_ALERT "exit module.\n");
}
module_init(maytures_init);
module_exit(maytures_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("maytures ");
MODULE_DESCRIPTION("A sample driver");
MODULE_SUPPORTED_DEVICE("testdevice");
Makefile :
#obj-m:= hello.o
PWD := $(shell pwd)
KERNELDIR := /home/cmz/MyProjects/omap3/code/ema_psp-02.01.03.11
all: default
obj-m += create_chrdev.o
#ARCH=arm
#CROSS_COMPILE=arm-none-linux-gnueabi-
default:
        $(MAKE) -C $(KERNELDIR) M=$(PWD) modules
clean:
        rm *.mod.c *.o *.ko




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