20150222 IMX257 Linux内存空间内存分配

  1 /*在内存中申请1k 大小的内存做为简单的一个设备来访问*/
  2 #include<linux/cdev.h>
  3 #include<linux/module.h>
  4 #include<linux/types.h>
  5 #include<linux/fs.h>
  6 #include<linux/errno.h>
  7 #include<linux/mm.h>
  8 #include<linux/sched.h>
  9 #include<linux/init.h>
 10 #include<asm/io.h>
 11 #include<asm/system.h>
 12 #include<asm/uaccess.h>
 13 #include<linux/device.h>
 14 #include <linux/vmalloc.h>
 15 
 16 #define Driver_NAME "kmalloc"
 17 #define DEVICE_NAME "kmalloc"
 18 
 19 static int major = 0;
 20 
 21 //auto to create device node
 22 static struct class *drv_class = NULL;
 23 static struct class_device *drv_class_dev = NULL;
 24 
 25 //定义内存分配的指针
 26 char *buf1 = NULL;
 27 char *buf2 = NULL;
 28 char *buf3 = NULL;
 29 
 30 static int key_open(struct inode *inode, struct file *file)
 31 {
 32     printk("<0>function open!\n\n");
 33     return 0;
 34 }
 35 
 36 static int key_read(struct file *filp, char __user *buff, size_t count, loff_t *offp)
 37 {
 38     return 0;
 39 }
 40 
 41 static ssize_t key_write(struct file *file, const char __user *buf, size_t count, loff_t * ppos)
 42 {
 43     printk("<0>function write!\n\n");
 44     return 1;
 45 }
 46 
 47 static int  key_release(struct inode *inode, struct file *filp)
 48 {
 49     printk("<0>function write!\n\n");
 50     return 0;
 51 }
 52 
 53 static int key_ioctl(struct inode *inode,struct file *flip,unsigned int command,unsigned long arg)
 54 {
 55     printk("<0>function ioctl!\n\n");
 56     return 0;
 57 }
 58 
 59 static struct file_operations key_fops = {
 60     .owner  =   THIS_MODULE,    /* 这是一个宏，推向编译模块时自动创建的__this_module变量 */
 61     .open   =   key_open,
 62     .read   =   key_read,
 63     .write  =   key_write,
 64     .release=   key_release,
 65     .ioctl  =   key_ioctl,
 66 };
 67 
 68 
 69 static int __init  key_irq_init(void)
 70 {
 71     printk("<0>\nHello,this is %s module!\n\n",Driver_NAME);
 72     //register and mknod
 73     major = register_chrdev(0,Driver_NAME,&key_fops);
 74     drv_class = class_create(THIS_MODULE,Driver_NAME);
 75     drv_class_dev = device_create(drv_class,NULL,MKDEV(major,0),NULL,DEVICE_NAME);  /*/dev/key_query*/
 76     
 77     //kmalloc分配内存实验1
 78     // buf1 申请一个100字节的物理内存,若无内存，则休眠
 79     buf1 = (unsigned char *)kmalloc(100,GFP_KERNEL);
 80     if(buf1 == NULL){
 81         printk("<0>buf1 kmalloc error !\n\n");
 82         return -1;
 83     }
 84     printk("<0>buf1 kmalloc mem addr = %x \n\n",buf1);
 85     memset(buf1,0,100);                                //将所分配到的内存清理
 86     strcpy(buf1,"<<------buf1 Kmalloc Mem OK!------>>");//向内存中写入数据
 87     printk("<0>BUF1: %s\n\n",buf1);                    //从内存中读出数据
 88 
 89     //get_zeroed_page申请分配整页内存，并且初始化为0
 90     buf2 = (unsigned char *)get_zeroed_page(GFP_KERNEL);
 91     if(buf2 == NULL){
 92         printk("<0>buf2 get_zeroed_page error !\n\n");
 93         return -1;
 94     }
 95     printk("<0>buf2 get_zeroed_page addr = %x \n\n",buf2);
 96     strcpy(buf2,"<<------buf2 get_zeroed_page OK!------>>");//向内存中写入数据
 97     printk("<0>BUF2: %s\n\n",buf2);
 98 
 99     //Vmalloc 申请1000000个字节（1M）的空间 虚拟地址分配（零碎的物理地址空间）
100     buf3 = (unsigned char *)vmalloc(1000000);
101     if(buf3 == NULL){
102         printk("<0>buf3 vmalloc error !\n\n");
103         return -1;
104     }
105     printk("<0>buf3 vmalloc addr = %x \n\n",buf3);
106     strcpy(buf3,"<<------buf3 vmalloc OK!------>>");//向内存中写入数据
107     printk("<0>BUF3: %s\n\n",buf3);
108     
109     return 0; 
110 }
111                      
112 static void __exit key_irq_exit(void)
113 {
114     printk("<0>\nGoodbye,%s!\n\n",Driver_NAME);
115 
116        unregister_chrdev(major,Driver_NAME);
117     device_unregister(drv_class_dev);
118     class_destroy(drv_class);
119 
120     //释放前面申请的内存
121     printk("<0>buf1 kfree addr = %x \n\n",buf1);
122     kfree(buf1);
123     printk("<0>buf2 free_page addr = %x \n\n",buf2);
124     free_page((unsigned long)buf2);
125     printk("<0>buf3 vfree addr = %x \n\n",buf3);
126     vfree(buf3);        
127     printk("<0><<------Module Exit!------>>\n\n");
128 
129 }
130 
131 
132 /* 这两行指定驱动程序的初始化函数和卸载函数 */
133 module_init(key_irq_init);
134 module_exit(key_irq_exit);
135 
136 /* 描述驱动程序的一些信息，不是必须的 */
137 MODULE_AUTHOR("Lover雪儿");
138 MODULE_VERSION("0.1.0");
139 MODULE_DESCRIPTION("IMX257 key Driver");
140 MODULE_LICENSE("GPL");