| commit | author | age | ||
| f5c330 | 1 | |
| G | 2 | #include <linux/module.h> |
| 3 | #include <linux/init.h> | |
| 4 | #include <linux/kernel.h> /* printk() */ | |
| 5 | #include <linux/slab.h> /* kmalloc() */ | |
| 6 | #include <linux/fs.h> /* everything... */ | |
| 7 | #include <linux/errno.h> /* error codes */ | |
| 8 | #include <linux/types.h> /* size_t */ | |
| 9 | #include <linux/cdev.h> /* cdev */ | |
| 10 | #include <linux/fcntl.h> /* O_ACCMODE */ | |
| 11 | #include <linux/uaccess.h> /* copy_*_user */ | |
| 12 | #include <linux/version.h> /* kernel version code */ | |
| 13 | #include <linux/moduleparam.h> | |
| 14 | ||
| 15 | #if LINUX_VERSION_CODE < KERNEL_VERSION(5,0,0) | |
| 16 | #define access_ok_wrapper(type,arg,cmd) access_ok(type, arg, cmd) | |
| 17 | #else | |
| 18 | #define access_ok_wrapper(type,arg,cmd) access_ok(arg, cmd) | |
| 19 | #endif | |
| 20 | ||
| 21 | /* ioctl definitions, use 'z' as magic number */ | |
| 22 | #define CHRDEV_IOC_MAGIC 'z' | |
| 23 | #define CHRDEV_IOCRESET _IO(CHRDEV_IOC_MAGIC, 0) | |
| 24 | #define CHRDEV_IOCSET _IOW(CHRDEV_IOC_MAGIC, 1, int) | |
| 25 | #define CHRDEV_IOCGET _IOR(CHRDEV_IOC_MAGIC, 2, int) | |
| 26 | #define CHRDEV_IOC_MAXNR 3 | |
| 27 | ||
| 28 | /* device name and major number */ | |
| 29 | #define DEV_NAME "chrdev" | |
| 30 | #define DEV_SIZE 1024 | |
| 31 | #define CONFIG_AUTODEV 1 /* Auto create device node in driver or not */ | |
| 32 | ||
| 33 | //#define DEV_MAJOR 79 | |
| 34 | #ifndef DEV_MAJOR | |
| 35 | #define DEV_MAJOR 0 | |
| 36 | #endif | |
| 37 | ||
| 38 | int dev_major = DEV_MAJOR; | |
| 39 | module_param(dev_major, int, S_IRUGO); | |
| 40 | ||
| 41 | typedef struct chrdev_s | |
| 42 | { | |
| 43 | struct cdev cdev; | |
| 44 | #ifdef CONFIG_AUTODEV | |
| 45 | struct class *class; | |
| 46 | struct device *device; | |
| 47 | #endif | |
| 48 | char *data; /* data buffer */ | |
| 49 | uint32_t size; /* data buffer size */ | |
| 50 | uint32_t bytes; /* data bytes in the buffer */ | |
| 51 | } chrdev_t; | |
| 52 | ||
| 53 | static struct chrdev_s dev; | |
| 54 | ||
| 55 | static ssize_t chrdev_read (struct file *file, char __user *buf, size_t count, loff_t *f_pos) | |
| 56 | { | |
| 57 | struct chrdev_s *dev = file->private_data; | |
| 58 | ssize_t nbytes; | |
| 59 | ssize_t rv = 0; | |
| 60 | ||
| 61 | /* no data in buffer */ | |
| 62 | if( !dev->bytes ) | |
| 63 | return 0; | |
| 64 | ||
| 65 | /* copy data to user space */ | |
| 66 | nbytes = count>dev->bytes ? dev->bytes : count; | |
| 67 | if( copy_to_user(buf, dev->data, nbytes) ) | |
| 68 | { | |
| 69 | rv = -EFAULT; | |
| 70 | goto out; | |
| 71 | } | |
| 72 | ||
| 73 | /* update return value and data bytes in buffer */ | |
| 74 | rv = nbytes; | |
| 75 | dev->bytes -= nbytes; | |
| 76 | ||
| 77 | out: | |
| 78 | return rv; | |
| 79 | } | |
| 80 | ||
| 81 | static ssize_t chrdev_write (struct file *file, const char __user *buf, size_t count, loff_t *f_pos) | |
| 82 | { | |
| 83 | struct chrdev_s *dev = file->private_data; | |
| 84 | ssize_t nbytes; | |
| 85 | ssize_t rv = 0; | |
| 86 | ||
| 87 | /* no space left */ | |
| 88 | if( dev->bytes >= dev->size ) | |
| 89 | return -ENOSPC; | |
| 90 | ||
| 91 | /* check copy data bytes */ | |
| 92 | if( dev->size - dev->bytes < count) | |
| 93 | nbytes = dev->size - dev->bytes; | |
| 94 | else | |
| 95 | nbytes = count; | |
| 96 | ||
| 97 | /* copy data from user space */ | |
| 98 | if( copy_from_user(&dev->data[dev->bytes], buf, nbytes) ) | |
| 99 | { | |
| 100 | rv = -EFAULT; | |
| 101 | goto out; | |
| 102 | } | |
| 103 | ||
| 104 | /* update return value and data bytes in buffer */ | |
| 105 | rv = nbytes; | |
| 106 | dev->bytes += nbytes; | |
| 107 | ||
| 108 | out: | |
| 109 | return rv; | |
| 110 | } | |
| 111 | ||
| 112 | /* The ioctl() implementation */ | |
| 113 | long chrdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg) | |
| 114 | { | |
| 115 | struct chrdev_s *dev = file->private_data; | |
| 116 | int rv, data; | |
| 117 | size_t bytes = sizeof(data); | |
| 118 | ||
| 119 | /* | |
| 120 | * extract the type and number bitfields, and don't decode | |
| 121 | * wrong cmds: return ENOTTY (inappropriate ioctl) before access_ok() | |
| 122 | */ | |
| 123 | if (_IOC_TYPE(cmd) != CHRDEV_IOC_MAGIC) return -ENOTTY; | |
| 124 | if (_IOC_NR(cmd) > CHRDEV_IOC_MAXNR) return -ENOTTY; | |
| 125 | ||
| 126 | /* | |
| 127 | * the direction is a bitmask, and VERIFY_WRITE catches R/W transfers. | |
| 128 | * `Type' is user-oriented, while access_ok is kernel-oriented, | |
| 129 | * so the concept of "read" and "write" is reversed | |
| 130 | */ | |
| 131 | if (_IOC_DIR(cmd) & _IOC_READ) | |
| 132 | rv = !access_ok_wrapper(VERIFY_WRITE, (void __user *)arg, _IOC_SIZE(cmd)); | |
| 133 | else if (_IOC_DIR(cmd) & _IOC_WRITE) | |
| 134 | rv = !access_ok_wrapper(VERIFY_READ, (void __user *)arg, _IOC_SIZE(cmd)); | |
| 135 | if (rv) return -EFAULT; | |
| 136 | ||
| 137 | switch(cmd) { | |
| 138 | case CHRDEV_IOCRESET: | |
| 139 | dev->bytes = 0; | |
| 140 | memset(dev->data, 0, dev->size); | |
| 141 | rv = 0; | |
| 142 | break; | |
| 143 | ||
| 144 | /* Last 4 bytes in the buffer used to save ioctl() data*/ | |
| 145 | case CHRDEV_IOCSET: | |
| 146 | rv = __get_user(data, (int __user *)arg); | |
| 147 | if( !rv ) | |
| 148 | memcpy(&dev->data[dev->size-bytes], &data, bytes); | |
| 149 | break; | |
| 150 | ||
| 151 | case CHRDEV_IOCGET: | |
| 152 | memcpy(&data, &dev->data[dev->size-bytes], bytes); | |
| 153 | rv = __put_user(data, (int __user *)arg); | |
| 154 | break; | |
| 155 | ||
| 156 | default: | |
| 157 | return -ENOTTY; | |
| 158 | } | |
| 159 | ||
| 160 | return rv; | |
| 161 | } | |
| 162 | ||
| 163 | static int chrdev_open (struct inode *inode, struct file *file) | |
| 164 | { | |
| 165 | struct chrdev_s *dev; /* device struct address */ | |
| 166 | ||
| 167 | /* get the device struct address by container_of() */ | |
| 168 | dev = container_of(inode->i_cdev, struct chrdev_s, cdev); | |
| 169 | ||
| 170 | /* save the device struct address for other methods */ | |
| 171 | file->private_data = dev; | |
| 172 | ||
| 173 | return 0; | |
| 174 | } | |
| 175 | ||
| 176 | static int chrdev_close (struct inode *node, struct file *file) | |
| 177 | { | |
| 178 | return 0; | |
| 179 | } | |
| 180 | ||
| 181 | static struct file_operations chrdev_fops = { | |
| 182 | .owner = THIS_MODULE, | |
| 183 | .open = chrdev_open, /* open() implementation */ | |
| 184 | .read = chrdev_read, /* read() implementation */ | |
| 185 | .write = chrdev_write, /* write() implementation */ | |
| 186 | .release = chrdev_close, /* close() implementation */ | |
| 187 | .unlocked_ioctl = chrdev_ioctl, /* ioctl() implementation */ | |
| 188 | }; | |
| 189 | ||
| 190 | static int __init chrdev_init(void) | |
| 191 | { | |
| 192 | dev_t devno; | |
| 193 | int rv; | |
| 194 | ||
| 195 | /* malloc and initial device read/write buffer */ | |
| 196 | dev.data = kmalloc(DEV_SIZE, GFP_KERNEL); | |
| 197 | if( !dev.data ) | |
| 198 | { | |
| 199 | printk(KERN_ERR " %s driver kmalloc() failed\n", DEV_NAME); | |
| 200 | return -ENOMEM; | |
| 201 | } | |
| 202 | dev.size = DEV_SIZE; | |
| 203 | dev.bytes = 0; | |
| 204 | memset(dev.data, 0, dev.size); | |
| 205 | ||
| 206 | /* dynamic alloc device node major number if not set */ | |
| 207 | if(0 != dev_major) | |
| 208 | { | |
| 209 | devno = MKDEV(dev_major, 0); | |
| 210 | rv = register_chrdev_region(devno, 1, DEV_NAME); | |
| 211 | } | |
| 212 | else | |
| 213 | { | |
| 214 | rv = alloc_chrdev_region(&devno, 0, 1, DEV_NAME); | |
| 215 | dev_major = MAJOR(devno); | |
| 216 | } | |
| 217 | ||
| 218 | if(rv < 0) | |
| 219 | { | |
| 220 | printk(KERN_ERR "%s driver can't use major %d\n", DEV_NAME, dev_major); | |
| 221 | return -ENODEV; | |
| 222 | } | |
| 223 | ||
| 224 | /* setup and register cdev into kernel */ | |
| 225 | cdev_init(&dev.cdev, &chrdev_fops); | |
| 226 | dev.cdev.owner = THIS_MODULE; | |
| 227 | rv = cdev_add(&dev.cdev, devno, 1); | |
| 228 | if( rv ) | |
| 229 | { | |
| 230 | rv = -ENODEV; | |
| 231 | printk(KERN_ERR "%s driver regist failed, rv=%d\n", DEV_NAME, rv); | |
| 232 | goto failed1; | |
| 233 | } | |
| 234 | ||
| 235 | #ifdef CONFIG_AUTODEV | |
| 236 | /* create device node in user space */ | |
| 237 | #if LINUX_VERSION_CODE >= KERNEL_VERSION(6, 5, 0) | |
| 238 | dev.class = class_create(DEV_NAME); | |
| 239 | #else | |
| 240 | dev.class = class_create(THIS_MODULE, DEV_NAME); | |
| 241 | #endif | |
| 242 | if (IS_ERR(dev.class)) { | |
| 243 | rv = PTR_ERR(dev.class); | |
| 244 | goto failed2; | |
| 245 | } | |
| 246 | ||
| 247 | dev.device = device_create(dev.class, NULL, MKDEV(dev_major, 0), NULL, DEV_NAME); | |
| 248 | if( !dev.device ) | |
| 249 | { | |
| 250 | rv = -ENODEV; | |
| 251 | printk(KERN_ERR "%s driver create device failed\n", DEV_NAME); | |
| 252 | goto failed3; | |
| 253 | } | |
| 254 | #endif | |
| 255 | ||
| 256 | printk(KERN_INFO "%s driver on major[%d] installed.\n", DEV_NAME, dev_major); | |
| 257 | return 0; | |
| 258 | ||
| 259 | #ifdef CONFIG_AUTODEV | |
| 260 | failed3: | |
| 261 | class_destroy(dev.class); | |
| 262 | ||
| 263 | failed2: | |
| 264 | cdev_del(&dev.cdev); | |
| 265 | #endif | |
| 266 | ||
| 267 | failed1: | |
| 268 | unregister_chrdev_region(devno, 1); | |
| 269 | kfree(dev.data); | |
| 270 | ||
| 271 | printk(KERN_ERR "%s driver installed failed.\n", DEV_NAME); | |
| 272 | return rv; | |
| 273 | } | |
| 274 | ||
| 275 | static void __exit chrdev_exit(void) | |
| 276 | { | |
| 277 | #ifdef CONFIG_AUTODEV | |
| 278 | device_del(dev.device); | |
| 279 | class_destroy(dev.class); | |
| 280 | #endif | |
| 281 | ||
| 282 | cdev_del(&dev.cdev); | |
| 283 | unregister_chrdev_region(MKDEV(dev_major,0), 1); | |
| 284 | ||
| 285 | kfree(dev.data); | |
| 286 | ||
| 287 | printk(KERN_INFO "%s driver removed!\n", DEV_NAME); | |
| 288 | return; | |
| 289 | } | |
| 290 | ||
| 291 | module_init(chrdev_init); | |
| 292 | module_exit(chrdev_exit); | |
| 293 | ||
| 294 | MODULE_LICENSE("Dual BSD/GPL"); | |
| 295 | MODULE_AUTHOR("GuoWenxue <guowenxue@gmail.com>"); | |
