????????

1. ??????????

?????????????????????

????????????????? arm-at91-linux-gnueabi-gcc?

?????????????????? menuconfig ???? .config ???

2. ??????????Makefile??

???Makefile?????????????????????????????

# ??KERNELRELEASE???????????ifneq ($(KERNELRELEASE),)    obj-m += xyy.oelse    # KERNELDIR ???????    KERNELDIR ?= /path_to_linux_src/linux-at91-linux-2.6.39-at91-20160713    PWD := $(shell pwd)endif# ????????????clean:    make -C $(KERNELDIR) M=$(PWD) modules ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- \    rm -rf *.o .*.cmd .tmp_versions *.mod.c modules.order Module.symvers *.ko.unsigned

3. ??????Makefile

???????????

? obj-m ??? .o ???????????????

? KERNELDIR ????????????

? CROSS_COMPILE ???????????????

???????? make ???????

4. ???? `obj-m`?

obj-y ??????? zImage?

obj-m ?????? .ko ????????? zImage?

3. ??????????????????????

?????????????

#include 
   
    #include 
    
     #include 
     
      #include 
      
       static int __init test_init(void) {    int ret = misc_register(&misc_dev);    if (ret) {        printk(KERN_ERR "[xyy] misc_register error\n");    } else {        printk(KERN_INFO "[xyy] test driver init\n");    }    return ret;}static void __exit test_exit(void) {    misc_deregister(&misc_dev);    printk(KERN_INFO "[xyy] test driver exit\n");}module_init(test_init);module_exit(test_exit);MODULE_AUTHOR("XXXXXBBBBB Corporation");MODULE_DESCRIPTION("XXXXXXXX machine main controller board IO test driver");MODULE_LICENSE("Dual BSD/GPL");MODULE_VERSION("1.0.0");

??????????

?????make

?????insmod xyy.ko

???????dmesg -c

?????rmmod xyy.ko

?? /dev ?????????ls /dev/Adam

4. ???????????????????

4.1 `MODULE_AUTHOR` ???

??????????????????????

MODULE_AUTHOR("XXXXXBBBBB Corporation");

4.2 `module_init` ? `module_exit`

????????????????

static int __init test_init(void) { ... }static void __exit test_exit(void) { ... }

4.3 `misc_register` ? `misc_deregister`

????????????

struct miscdevice misc_dev = { .minor = MISC_DYNAMIC_MINOR, .name = "Adam" };misc_register(&misc_dev);

5. ???????? `ioctl`?????????????

??????? ioctl ??????

#include 
   
    #include 
    
     #include 
     
      #include 
      
       #include 
       
        #include 
        
         #include 
         
          struct test { int a; short b; char c;};struct file_operations io_ops = { .owner = THIS_MODULE, .release = io_release, .open = io_open, .ioctl = io_ioctl,};static int io_open(struct inode *inode, struct file *filp) { printk("[xyy] Open called!!\n"); return 0;}static int io_release(struct inode *inode, struct file *file) { printk("[xyy] close called!!\n"); return 0;}static int io_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) { printk("cmd = %x\n", cmd); printk("arg: %p\n", (void *)arg); struct test t = { 0, 0, 0 }; int ret = copy_from_user(&t, (struct test *)arg, sizeof(t)); printk("ret = %d, t.a = %d, t.b = %d, t.c = %d\n", ret, t.a, t.b, t.c); t.a = 111; t.b = 222; t.c = 33; ret = copy_to_user((struct test *)arg, &t, sizeof(t)); return 0;}struct miscdevice misc_dev = { .minor = MISC_DYNAMIC_MINOR, .name = "Adam", .fops = &io_ops,};static int __init test_init(void) { int ret = misc_register(&misc_dev); if (ret) { printk(KERN_ERR "[xyy] misc_register error\n"); } else { printk(KERN_INFO "[xyy] test driver init\n"); } return ret;}static void __exit test_exit(void) { misc_deregister(&misc_dev); printk(KERN_INFO "[xyy] test driver exit\n");}module_init(test_init);module_exit(test_exit);MODULE_AUTHOR("XXXXXBBBBB Corporation");MODULE_DESCRIPTION("XXXXXXXX machine main controller board IO test driver");MODULE_LICENSE("Dual BSD/GPL");MODULE_VERSION("1.0.0");

5. ????

?????????

#include 
   
    #include 
    
     #include 
     
      #include 
      
       struct test {    int a;    short b;    char c;};int main(void) {    int fd = open("/dev/Adam", O_RDONLY);    if (fd < 0) {        puts("open fail\n");        return -1;    }    struct test t = { 100, 20, 10 };    printf("tt: %p\n", &t);    int ret = ioctl(fd, 0x11223344, &t);    if (ret != 0) {        puts("ioctl fail\n");    } else {        printf("ret = %d, t.a = %d, t.b = %d, t.c = %d\n", ret, t.a, t.b, t.c);    }    close(fd);    return 0;}