| 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 | /* device name and major number */ | |
| 16 | #define DEV_NAME "chrdev" | |
| 17 | #define DEV_SIZE 1024 | |
| 18 | #define CONFIG_AUTODEV 1 /* Auto create device node in driver or not */ | |
| 19 | ||
| 20 | //#define DEV_MAJOR 79 | |
| 21 | #ifndef DEV_MAJOR | |
| 22 | #define DEV_MAJOR 0 | |
| 23 | #endif | |
| 24 | ||
| 25 | int dev_major = DEV_MAJOR; | |
| 26 | module_param(dev_major, int, S_IRUGO); | |
| 27 | ||
| 28 | typedef struct chrdev_s | |
| 29 | { | |
| 30 | struct cdev cdev; | |
| 31 | #ifdef CONFIG_AUTODEV | |
| 32 | struct class *class; | |
| 33 | struct device *device; | |
| 34 | #endif | |
| 35 | char *data; /* data buffer */ | |
| 36 | uint32_t size; /* data buffer size */ | |
| 37 | uint32_t bytes; /* data bytes in the buffer */ | |
| 38 | } chrdev_t; | |
| 39 | ||
| 40 | static struct chrdev_s dev; | |
| 41 | ||
| 42 | static ssize_t chrdev_read (struct file *file, char __user *buf, size_t count, loff_t *f_pos) | |
| 43 | { | |
| 44 | struct chrdev_s *dev = file->private_data; | |
| 45 | ssize_t nbytes; | |
| 46 | ssize_t rv = 0; | |
| 47 | ||
| 48 | /* no data in buffer */ | |
| 49 | if( !dev->bytes ) | |
| 50 | return 0; | |
| 51 | ||
| 52 | /* copy data to user space */ | |
| 53 | nbytes = count>dev->bytes ? dev->bytes : count; | |
| 54 | if( copy_to_user(buf, dev->data, nbytes) ) | |
| 55 | { | |
| 56 | rv = -EFAULT; | |
| 57 | goto out; | |
| 58 | } | |
| 59 | ||
| 60 | /* update return value and data bytes in buffer */ | |
| 61 | rv = nbytes; | |
| 62 | dev->bytes -= nbytes; | |
| 63 | ||
| 64 | out: | |
| 65 | return rv; | |
| 66 | } | |
| 67 | ||
| 68 | static ssize_t chrdev_write (struct file *file, const char __user *buf, size_t count, loff_t *f_pos) | |
| 69 | { | |
| 70 | struct chrdev_s *dev = file->private_data; | |
| 71 | ssize_t nbytes; | |
| 72 | ssize_t rv = 0; | |
| 73 | ||
| 74 | /* no space left */ | |
| 75 | if( dev->bytes >= dev->size ) | |
| 76 | return -ENOSPC; | |
| 77 | ||
| 78 | /* check copy data bytes */ | |
| 79 | if( dev->size - dev->bytes < count) | |
| 80 | nbytes = dev->size - dev->bytes; | |
| 81 | else | |
| 82 | nbytes = count; | |
| 83 | ||
| 84 | /* copy data from user space */ | |
| 85 | if( copy_from_user(&dev->data[dev->bytes], buf, nbytes) ) | |
| 86 | { | |
| 87 | rv = -EFAULT; | |
| 88 | goto out; | |
| 89 | } | |
| 90 | ||
| 91 | /* update return value and data bytes in buffer */ | |
| 92 | rv = nbytes; | |
| 93 | dev->bytes += nbytes; | |
| 94 | ||
| 95 | out: | |
| 96 | return rv; | |
| 97 | } | |
| 98 | ||
| 99 | static int chrdev_open (struct inode *inode, struct file *file) | |
| 100 | { | |
| 101 | struct chrdev_s *dev; /* device struct address */ | |
| 102 | ||
| 103 | /* get the device struct address by container_of() */ | |
| 104 | dev = container_of(inode->i_cdev, struct chrdev_s, cdev); | |
| 105 | ||
| 106 | /* save the device struct address for other methods */ | |
| 107 | file->private_data = dev; | |
| 108 | ||
| 109 | return 0; | |
| 110 | } | |
| 111 | ||
| 112 | static int chrdev_close (struct inode *node, struct file *file) | |
| 113 | { | |
| 114 | return 0; | |
| 115 | } | |
| 116 | ||
| 117 | static struct file_operations chrdev_fops = { | |
| 118 | .owner = THIS_MODULE, | |
| 119 | .open = chrdev_open, /* open() implementation */ | |
| 120 | .read = chrdev_read, /* read() implementation */ | |
| 121 | .write = chrdev_write, /* write() implementation */ | |
| 122 | .release = chrdev_close, /* close() implementation */ | |
| 123 | }; | |
| 124 | ||
| 125 | static int __init chrdev_init(void) | |
| 126 | { | |
| 127 | dev_t devno; | |
| 128 | int rv; | |
| 129 | ||
| 130 | /* malloc and initial device read/write buffer */ | |
| 131 | dev.data = kmalloc(DEV_SIZE, GFP_KERNEL); | |
| 132 | if( !dev.data ) | |
| 133 | { | |
| 134 | printk(KERN_ERR " %s driver kmalloc() failed\n", DEV_NAME); | |
| 135 | return -ENOMEM; | |
| 136 | } | |
| 137 | dev.size = DEV_SIZE; | |
| 138 | dev.bytes = 0; | |
| 139 | memset(dev.data, 0, dev.size); | |
| 140 | ||
| 141 | /* dynamic alloc device node major number if not set */ | |
| 142 | if(0 != dev_major) | |
| 143 | { | |
| 144 | devno = MKDEV(dev_major, 0); | |
| 145 | rv = register_chrdev_region(devno, 1, DEV_NAME); | |
| 146 | } | |
| 147 | else | |
| 148 | { | |
| 149 | rv = alloc_chrdev_region(&devno, 0, 1, DEV_NAME); | |
| 150 | dev_major = MAJOR(devno); | |
| 151 | } | |
| 152 | ||
| 153 | if(rv < 0) | |
| 154 | { | |
| 155 | printk(KERN_ERR "%s driver can't use major %d\n", DEV_NAME, dev_major); | |
| 156 | return -ENODEV; | |
| 157 | } | |
| 158 | ||
| 159 | /* setup and register cdev into kernel */ | |
| 160 | cdev_init(&dev.cdev, &chrdev_fops); | |
| 161 | dev.cdev.owner = THIS_MODULE; | |
| 162 | rv = cdev_add(&dev.cdev, devno, 1); | |
| 163 | if( rv ) | |
| 164 | { | |
| 165 | rv = -ENODEV; | |
| 166 | printk(KERN_ERR "%s driver regist failed, rv=%d\n", DEV_NAME, rv); | |
| 167 | goto failed1; | |
| 168 | } | |
| 169 | ||
| 170 | #ifdef CONFIG_AUTODEV | |
| 171 | /* create device node in user space */ | |
| 172 | #if LINUX_VERSION_CODE >= KERNEL_VERSION(6, 5, 0) | |
| 173 | dev.class = class_create(DEV_NAME); | |
| 174 | #else | |
| 175 | dev.class = class_create(THIS_MODULE, DEV_NAME); | |
| 176 | #endif | |
| 177 | if (IS_ERR(dev.class)) { | |
| 178 | rv = PTR_ERR(dev.class); | |
| 179 | goto failed2; | |
| 180 | } | |
| 181 | ||
| 182 | dev.device = device_create(dev.class, NULL, MKDEV(dev_major, 0), NULL, DEV_NAME); | |
| 183 | if( !dev.device ) | |
| 184 | { | |
| 185 | rv = -ENODEV; | |
| 186 | printk(KERN_ERR "%s driver create device failed\n", DEV_NAME); | |
| 187 | goto failed3; | |
| 188 | } | |
| 189 | #endif | |
| 190 | ||
| 191 | printk(KERN_INFO "%s driver on major[%d] installed.\n", DEV_NAME, dev_major); | |
| 192 | return 0; | |
| 193 | ||
| 194 | #ifdef CONFIG_AUTODEV | |
| 195 | failed3: | |
| 196 | class_destroy(dev.class); | |
| 197 | ||
| 198 | failed2: | |
| 199 | cdev_del(&dev.cdev); | |
| 200 | #endif | |
| 201 | ||
| 202 | failed1: | |
| 203 | unregister_chrdev_region(devno, 1); | |
| 204 | kfree(dev.data); | |
| 205 | ||
| 206 | printk(KERN_ERR "%s driver installed failed.\n", DEV_NAME); | |
| 207 | return rv; | |
| 208 | } | |
| 209 | ||
| 210 | static void __exit chrdev_exit(void) | |
| 211 | { | |
| 212 | #ifdef CONFIG_AUTODEV | |
| 213 | device_del(dev.device); | |
| 214 | class_destroy(dev.class); | |
| 215 | #endif | |
| 216 | ||
| 217 | cdev_del(&dev.cdev); | |
| 218 | unregister_chrdev_region(MKDEV(dev_major,0), 1); | |
| 219 | ||
| 220 | kfree(dev.data); | |
| 221 | ||
| 222 | printk(KERN_INFO "%s driver removed!\n", DEV_NAME); | |
| 223 | return; | |
| 224 | } | |
| 225 | ||
| 226 | module_init(chrdev_init); | |
| 227 | module_exit(chrdev_exit); | |
| 228 | ||
| 229 | MODULE_LICENSE("Dual BSD/GPL"); | |
| 230 | MODULE_AUTHOR("GuoWenxue <guowenxue@gmail.com>"); | |
