1 #include <linux/module.h> //MODULE_LICENSE("GPL"); 2 #include <linux/init.h> //module_init module_exit 3 #include <linux/kernel.h> //printk 4 #include <linux/io.h> //ioremap iounremap 5 #include <linux/ioport.h> //request_mem_region 6 7 8 #include <linux/miscdevice.h> 9 #include <linux/fs.h> //file_operations 结构体的定义 10 #include <linux/slab.h> //kmalloc 11 #include <linux/delay.h> 12 13 #include <asm/uaccess.h> //copy_to_user copy_form_user 14 15 #include <linux/spinlock.h> //自旋锁 16 #include <linux/rwlock.h> //读写自旋锁 17 #include <linux/seqlock.h> //顺序锁 18 19 /* 20 该设备只能同时被一个进程打开 21 */ 22 23 24 #define DEVNAME "my_led" 25 #define MEMSIZE 100 26 27 28 int test = 1; 29 30 struct ldm_info 31 { 32 struct miscdevice dev; //设备节点 33 struct file_operations ops; //文件操作 34 unsigned char mem[MEMSIZE] ; //数组, 内核的空间 35 //rwlock_t myrwlock; 36 seqlock_t seq; 37 }; 38 39 //struct ldm_info ldm; 40 struct ldm_info ldm; //结构体的指针,分配空间 41 42 static int ldm_open(struct inode * inode, struct file * file) 43 { 44 //printk("kernel: ldm_open "); 45 test++; 46 //如何传递私有变量 47 //Linux任何一个文件,都会有一个file指针, 48 //有一个成员 private_data void * 通用指针 49 file->private_data = (void *)&test; 50 51 return 0; 52 } 53 54 /* 55 copy_to_user 56 copy_form_user 57 */ 58 59 static ssize_t ldm_write(struct file * file, const char __user * buf, size_t size, loff_t * offt) 60 { 61 int i =0; 62 63 int val = *(int *)file->private_data; 64 65 //write_lock(&ldm.myrwlock); 66 write_seqlock(&ldm.seq); 67 for(;i < size; i++) { 68 //每拷贝一个字节,睡眠1s 69 copy_from_user(ldm.mem + i, buf + i, 1); 70 printk("write:%c val = %d ", ldm.mem[i], val); 71 ssleep(1); //延迟1s 72 } 73 //write_unlock(&ldm.myrwlock); 74 write_sequnlock(&ldm.seq); 75 76 return 0; 77 } 78 79 80 ssize_t ldm_read(struct file * file, char __user * buf, size_t size, loff_t * offt) 81 { 82 //每隔一秒拷贝一个字节到用户层 83 int i =0; 84 85 int val = *(int *)file->private_data; 86 87 int seq = 0; 88 do { 89 seq = read_seqbegin(&ldm.seq); 90 //printk("seq = %d ", seq); 91 92 for(;i < size; i++) { 93 //seq = read_seqbegin(&ldm.seq); 94 //每拷贝一个字节,睡眠1s 95 copy_to_user(buf + i, ldm.mem + i, 1); 96 printk("read:%c, val = %d ", ldm.mem[i], val); 97 ssleep(1); //延迟1s 98 } 99 }while(read_seqretry(&ldm.seq, seq)); 100 101 return 0; 102 } 103 104 int ldm_release(struct inode * inode, struct file *file) 105 { 106 //printk("kernel: close "); 107 test--; 108 return 0; 109 } 110 111 static int test_init(void) 112 { 113 int ret = 0; 114 115 printk("%s:%s:%d init ", __FILE__, __FUNCTION__, __LINE__); 116 117 118 ldm.dev.minor = MISC_DYNAMIC_MINOR; //系统自动分配次设备 119 ldm.dev.name = DEVNAME;//该名称将决定节点名称, 成功注册 linux 系统中 120 ldm.dev.fops = &ldm.ops; //关联文件操作 121 ldm.ops.open = ldm_open; 122 ldm.ops.write = ldm_write; 123 ldm.ops.read = ldm_read; 124 ldm.ops.release = ldm_release; 125 126 127 ret = misc_register(&ldm.dev); 128 129 //rwlock_init(&ldm.myrwlock); 130 seqlock_init(&ldm.seq); 131 132 if(ret < 0) { 133 printk("misc_register failed "); 134 goto err_misc_register; 135 } 136 137 return 0; 138 err_misc_register: 139 return ret; 140 141 } 142 143 //卸载 144 static void test_exit(void) 145 { 146 printk("%s:%s:%d init ", __FILE__, __FUNCTION__, __LINE__); 147 148 149 //注销misc 150 misc_deregister(&ldm.dev); 151 //释放映射的虚拟地址 152 153 } 154 155 module_init(test_init); 156 module_exit(test_exit); 157 158 159 MODULE_LICENSE("GPL"); //加入GPL许可