drivers/char/mem.c

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 1 /*
 2  * linux/drivers/char/mem.c
 3  *
 4  * Copyright (C) 1991, 1992 Linus Torvalds
 5  */
 6
 7 #include <linux/config.h>
 8 #include <linux/types.h>
 9 #include <linux/errno.h>
 10 #include <linux/sched.h>
 11 #include <linux/kernel.h>
 12 #include <linux/major.h>
 13 #include <linux/tty.h>
 14 #include <linux/miscdevice.h>
 15 #include <linux/tpqic02.h>
 16 #include <linux/ftape.h>
 17 #include <linux/malloc.h>
 18 #include <linux/mman.h>
 19 #include <linux/mm.h>
 20 #include <linux/random.h>
 21
 22 #include <asm/segment.h>
 23 #include <asm/io.h>
 24 #include <asm/pgtable.h>
 25
 26 #ifdef CONFIG_SOUND
 27 voidsoundcard_init(void);
 28 #endif
 29 #ifdef CONFIG_ISDN
 30 voidisdn_init(void);
 31 #endif
 32
 33 static intread_ram(struct inode * inode,struct file * file,char* buf,int count)
 34 {
 35 return-EIO;
 36 }
 37
 38 static intwrite_ram(struct inode * inode,struct file * file,const char* buf,int count)
 39 {
 40 return-EIO;
 41 }
 42
 43 static intread_mem(struct inode * inode,struct file * file,char* buf,int count)
 44 {
 45 unsigned long p = file->f_pos;
 46 int read;
 47
 48  p += PAGE_OFFSET;
 49 if(count <0)
 50 return-EINVAL;
 51 if(MAP_NR(p) >=MAP_NR(high_memory))
 52 return0;
 53 if(count > high_memory - p)
 54  count = high_memory - p;
 55  read =0;
 56 #if defined(__i386__)/* we don't have page 0 mapped on x86.. */
 57 while(p < PAGE_OFFSET + PAGE_SIZE && count >0) {
 58 put_user(0,buf);
 59  buf++;
 60  p++;
 61  count--;
 62  read++;
 63 }
 64 #endif
 65 memcpy_tofs(buf, (void*) p, count);
 66  read += count;
 67  file->f_pos += read;
 68 return read;
 69 }
 70
 71 static intwrite_mem(struct inode * inode,struct file * file,const char* buf,int count)
 72 {
 73 unsigned long p = file->f_pos;
 74 int written;
 75
 76  p += PAGE_OFFSET;
 77 if(count <0)
 78 return-EINVAL;
 79 if(MAP_NR(p) >=MAP_NR(high_memory))
 80 return0;
 81 if(count > high_memory - p)
 82  count = high_memory - p;
 83  written =0;
 84 #if defined(__i386__)/* we don't have page 0 mapped on x86.. */
 85 while(PAGE_OFFSET + p < PAGE_SIZE && count >0) {
 86 /* Hmm. Do something? */
 87  buf++;
 88  p++;
 89  count--;
 90  written++;
 91 }
 92 #endif
 93 memcpy_fromfs((void*) p, buf, count);
 94  written += count;
 95  file->f_pos += written;
 96 return count;
 97 }
 98
 99 static intmmap_mem(struct inode * inode,struct file * file,struct vm_area_struct * vma)
 100 {
 101 if(vma->vm_offset & ~PAGE_MASK)
 102 return-ENXIO;
 103 #if defined(__i386__)
 104 /*
 105  * hmm.. This disables high-memory caching, as the XFree86 team
 106  * wondered about that at one time.
 107  * The surround logic should disable caching for the high device
 108  * addresses anyway, but right now this seems still needed.
 109  */
 110 if(x86 >3&& vma->vm_offset >= high_memory)
 111 pgprot_val(vma->vm_page_prot) |= _PAGE_PCD;
 112 #endif
 113 if(remap_page_range(vma->vm_start, vma->vm_offset, vma->vm_end - vma->vm_start, vma->vm_page_prot))
 114 return-EAGAIN;
 115  vma->vm_inode = inode;
 116  inode->i_count++;
 117 return0;
 118 }
 119
 120 static intread_kmem(struct inode *inode,struct file *file,char*buf,int count)
 121 {
 122 int read1, read2;
 123
 124  read1 =read_mem(inode, file, buf, count);
 125 if(read1 <0)
 126 return read1;
 127  read2 =vread(buf + read1, (char*) ((unsigned long) file->f_pos), count - read1);
 128 if(read2 <0)
 129 return read2;
 130  file->f_pos += read2;
 131 return read1 + read2;
 132 }
 133
 134 static intread_port(struct inode * inode,struct file * file,char* buf,int count)
 135 {
 136 unsigned int i = file->f_pos;
 137 char* tmp = buf;
 138
 139 while(count-- >0&& i <65536) {
 140 put_user(inb(i),tmp);
 141  i++;
 142  tmp++;
 143 }
 144  file->f_pos = i;
 145 return tmp-buf;
 146 }
 147
 148 static intwrite_port(struct inode * inode,struct file * file,const char* buf,int count)
 149 {
 150 unsigned int i = file->f_pos;
 151 const char* tmp = buf;
 152
 153 while(count-- >0&& i <65536) {
 154 outb(get_user(tmp),i);
 155  i++;
 156  tmp++;
 157 }
 158  file->f_pos = i;
 159 return tmp-buf;
 160 }
 161
 162 static intread_null(struct inode * node,struct file * file,char* buf,int count)
 163 {
 164 return0;
 165 }
 166
 167 static intwrite_null(struct inode * inode,struct file * file,const char* buf,int count)
 168 {
 169 return count;
 170 }
 171
 172 static intread_zero(struct inode * node,struct file * file,char* buf,int count)
 173 {
 174 int left;
 175
 176 for(left = count; left >0; left--) {
 177 put_user(0,buf);
 178  buf++;
 179 }
 180 return count;
 181 }
 182
 183 static intmmap_zero(struct inode * inode,struct file * file,struct vm_area_struct * vma)
 184 {
 185 if(vma->vm_flags & VM_SHARED)
 186 return-EINVAL;
 187 if(zeromap_page_range(vma->vm_start, vma->vm_end - vma->vm_start, vma->vm_page_prot))
 188 return-EAGAIN;
 189 return0;
 190 }
 191
 192 static intread_full(struct inode * node,struct file * file,char* buf,int count)
 193 {
 194 return count;
 195 }
 196
 197 static intwrite_full(struct inode * inode,struct file * file,const char* buf,int count)
 198 {
 199 return-ENOSPC;
 200 }
 201
 202 /*
 203  * Special lseek() function for /dev/null and /dev/zero. Most notably, you can fopen()
 204  * both devices with "a" now. This was previously impossible. SRB.
 205  */
 206
 207 static intnull_lseek(struct inode * inode,struct file * file, off_t offset,int orig)
 208 {
 209 return file->f_pos=0;
 210 }
 211 /*
 212  * The memory devices use the full 32/64 bits of the offset, and so we cannot
 213  * check against negative addresses: they are ok. The return value is weird,
 214  * though, in that case (0).
 215  *
 216  * also note that seeking relative to the "end of file" isn't supported:
 217  * it has no meaning, so it returns -EINVAL.
 218  */
 219 static intmemory_lseek(struct inode * inode,struct file * file, off_t offset,int orig)
 220 {
 221 switch(orig) {
 222 case0:
 223  file->f_pos = offset;
 224 return file->f_pos;
 225 case1:
 226  file->f_pos += offset;
 227 return file->f_pos;
 228 default:
 229 return-EINVAL;
 230 }
 231 if(file->f_pos <0)
 232 return0;
 233 return file->f_pos;
 234 }
 235
 236 #define write_kmem write_mem
 237 #define mmap_kmem mmap_mem
 238 #define zero_lseek null_lseek
 239 #define write_zero write_null
 240
 241 static struct file_operations ram_fops = {
 242  memory_lseek,
 243  read_ram,
 244  write_ram,
 245  NULL,/* ram_readdir */
 246  NULL,/* ram_select */
 247  NULL,/* ram_ioctl */
 248  NULL,/* ram_mmap */
 249  NULL,/* no special open code */
 250  NULL,/* no special release code */
 251  NULL /* fsync */
 252 };
 253
 254 static struct file_operations mem_fops = {
 255  memory_lseek,
 256  read_mem,
 257  write_mem,
 258  NULL,/* mem_readdir */
 259  NULL,/* mem_select */
 260  NULL,/* mem_ioctl */
 261  mmap_mem,
 262  NULL,/* no special open code */
 263  NULL,/* no special release code */
 264  NULL /* fsync */
 265 };
 266
 267 static struct file_operations kmem_fops = {
 268  memory_lseek,
 269  read_kmem,
 270  write_kmem,
 271  NULL,/* kmem_readdir */
 272  NULL,/* kmem_select */
 273  NULL,/* kmem_ioctl */
 274  mmap_kmem,
 275  NULL,/* no special open code */
 276  NULL,/* no special release code */
 277  NULL /* fsync */
 278 };
 279
 280 static struct file_operations null_fops = {
 281  null_lseek,
 282  read_null,
 283  write_null,
 284  NULL,/* null_readdir */
 285  NULL,/* null_select */
 286  NULL,/* null_ioctl */
 287  NULL,/* null_mmap */
 288  NULL,/* no special open code */
 289  NULL,/* no special release code */
 290  NULL /* fsync */
 291 };
 292
 293 static struct file_operations port_fops = {
 294  memory_lseek,
 295  read_port,
 296  write_port,
 297  NULL,/* port_readdir */
 298  NULL,/* port_select */
 299  NULL,/* port_ioctl */
 300  NULL,/* port_mmap */
 301  NULL,/* no special open code */
 302  NULL,/* no special release code */
 303  NULL /* fsync */
 304 };
 305
 306 static struct file_operations zero_fops = {
 307  zero_lseek,
 308  read_zero,
 309  write_zero,
 310  NULL,/* zero_readdir */
 311  NULL,/* zero_select */
 312  NULL,/* zero_ioctl */
 313  mmap_zero,
 314  NULL,/* no special open code */
 315  NULL /* no special release code */
 316 };
 317
 318 static struct file_operations full_fops = {
 319  memory_lseek,
 320  read_full,
 321  write_full,
 322  NULL,/* full_readdir */
 323  NULL,/* full_select */
 324  NULL,/* full_ioctl */
 325  NULL,/* full_mmap */
 326  NULL,/* no special open code */
 327  NULL /* no special release code */
 328 };
 329
 330 static intmemory_open(struct inode * inode,struct file * filp)
 331 {
 332 switch(MINOR(inode->i_rdev)) {
 333 case0:
 334  filp->f_op = &ram_fops;
 335 break;
 336 case1:
 337  filp->f_op = &mem_fops;
 338 break;
 339 case2:
 340  filp->f_op = &kmem_fops;
 341 break;
 342 case3:
 343  filp->f_op = &null_fops;
 344 break;
 345 case4:
 346  filp->f_op = &port_fops;
 347 break;
 348 case5:
 349  filp->f_op = &zero_fops;
 350 break;
 351 case7:
 352  filp->f_op = &full_fops;
 353 break;
 354 case8:
 355  filp->f_op = &random_fops;
 356 break;
 357 case9:
 358  filp->f_op = &urandom_fops;
 359 break;
 360 default:
 361 return-ENODEV;
 362 }
 363 if(filp->f_op && filp->f_op->open)
 364 return filp->f_op->open(inode,filp);
 365 return0;
 366 }
 367
 368 static struct file_operations memory_fops = {
 369  NULL,/* lseek */
 370  NULL,/* read */
 371  NULL,/* write */
 372  NULL,/* readdir */
 373  NULL,/* select */
 374  NULL,/* ioctl */
 375  NULL,/* mmap */
 376  memory_open,/* just a selector for the real open */
 377  NULL,/* release */
 378  NULL /* fsync */
 379 };
 380
 381 intchr_dev_init(void)
 382 {
 383 if(register_chrdev(MEM_MAJOR,"mem",&memory_fops))
 384 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
 385 rand_initialize();
 386 tty_init();
 387 #ifdef CONFIG_PRINTER
 388 lp_init();
 389 #endif
 390 #if defined (CONFIG_BUSMOUSE) || defined(CONFIG_UMISC) || \
 391  defined (CONFIG_PSMOUSE) || defined (CONFIG_MS_BUSMOUSE) || \
 392  defined (CONFIG_ATIXL_BUSMOUSE) || defined(CONFIG_SOFT_WATCHDOG) || \
 393  defined (CONFIG_APM)
 394 misc_init();
 395 #endif
 396 #ifdef CONFIG_SOUND
 397 soundcard_init();
 398 #endif
 399 #if CONFIG_QIC02_TAPE
 400 qic02_tape_init();
 401 #endif
 402 #if CONFIG_ISDN
 403 isdn_init();
 404 #endif
 405 #ifdef CONFIG_FTAPE
 406 ftape_init();
 407 #endif
 408 return0;
 409 }