Linux-2.6.12-rc2
[linux-2.6.git] / drivers / char / mem.c
1 /*
2  *  linux/drivers/char/mem.c
3  *
4  *  Copyright (C) 1991, 1992  Linus Torvalds
5  *
6  *  Added devfs support. 
7  *    Jan-11-1998, C. Scott Ananian <cananian@alumni.princeton.edu>
8  *  Shared /dev/zero mmaping support, Feb 2000, Kanoj Sarcar <kanoj@sgi.com>
9  */
10
11 #include <linux/config.h>
12 #include <linux/mm.h>
13 #include <linux/miscdevice.h>
14 #include <linux/slab.h>
15 #include <linux/vmalloc.h>
16 #include <linux/mman.h>
17 #include <linux/random.h>
18 #include <linux/init.h>
19 #include <linux/raw.h>
20 #include <linux/tty.h>
21 #include <linux/capability.h>
22 #include <linux/smp_lock.h>
23 #include <linux/devfs_fs_kernel.h>
24 #include <linux/ptrace.h>
25 #include <linux/device.h>
26 #include <linux/backing-dev.h>
27
28 #include <asm/uaccess.h>
29 #include <asm/io.h>
30
31 #ifdef CONFIG_IA64
32 # include <linux/efi.h>
33 #endif
34
35 #if defined(CONFIG_S390_TAPE) && defined(CONFIG_S390_TAPE_CHAR)
36 extern void tapechar_init(void);
37 #endif
38
39 /*
40  * Architectures vary in how they handle caching for addresses
41  * outside of main memory.
42  *
43  */
44 static inline int uncached_access(struct file *file, unsigned long addr)
45 {
46 #if defined(__i386__)
47         /*
48          * On the PPro and successors, the MTRRs are used to set
49          * memory types for physical addresses outside main memory,
50          * so blindly setting PCD or PWT on those pages is wrong.
51          * For Pentiums and earlier, the surround logic should disable
52          * caching for the high addresses through the KEN pin, but
53          * we maintain the tradition of paranoia in this code.
54          */
55         if (file->f_flags & O_SYNC)
56                 return 1;
57         return !( test_bit(X86_FEATURE_MTRR, boot_cpu_data.x86_capability) ||
58                   test_bit(X86_FEATURE_K6_MTRR, boot_cpu_data.x86_capability) ||
59                   test_bit(X86_FEATURE_CYRIX_ARR, boot_cpu_data.x86_capability) ||
60                   test_bit(X86_FEATURE_CENTAUR_MCR, boot_cpu_data.x86_capability) )
61           && addr >= __pa(high_memory);
62 #elif defined(__x86_64__)
63         /* 
64          * This is broken because it can generate memory type aliases,
65          * which can cause cache corruptions
66          * But it is only available for root and we have to be bug-to-bug
67          * compatible with i386.
68          */
69         if (file->f_flags & O_SYNC)
70                 return 1;
71         /* same behaviour as i386. PAT always set to cached and MTRRs control the
72            caching behaviour. 
73            Hopefully a full PAT implementation will fix that soon. */      
74         return 0;
75 #elif defined(CONFIG_IA64)
76         /*
77          * On ia64, we ignore O_SYNC because we cannot tolerate memory attribute aliases.
78          */
79         return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
80 #else
81         /*
82          * Accessing memory above the top the kernel knows about or through a file pointer
83          * that was marked O_SYNC will be done non-cached.
84          */
85         if (file->f_flags & O_SYNC)
86                 return 1;
87         return addr >= __pa(high_memory);
88 #endif
89 }
90
91 #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
92 static inline int valid_phys_addr_range(unsigned long addr, size_t *count)
93 {
94         unsigned long end_mem;
95
96         end_mem = __pa(high_memory);
97         if (addr >= end_mem)
98                 return 0;
99
100         if (*count > end_mem - addr)
101                 *count = end_mem - addr;
102
103         return 1;
104 }
105 #endif
106
107 /*
108  * This funcion reads the *physical* memory. The f_pos points directly to the 
109  * memory location. 
110  */
111 static ssize_t read_mem(struct file * file, char __user * buf,
112                         size_t count, loff_t *ppos)
113 {
114         unsigned long p = *ppos;
115         ssize_t read, sz;
116         char *ptr;
117
118         if (!valid_phys_addr_range(p, &count))
119                 return -EFAULT;
120         read = 0;
121 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
122         /* we don't have page 0 mapped on sparc and m68k.. */
123         if (p < PAGE_SIZE) {
124                 sz = PAGE_SIZE - p;
125                 if (sz > count) 
126                         sz = count; 
127                 if (sz > 0) {
128                         if (clear_user(buf, sz))
129                                 return -EFAULT;
130                         buf += sz; 
131                         p += sz; 
132                         count -= sz; 
133                         read += sz; 
134                 }
135         }
136 #endif
137
138         while (count > 0) {
139                 /*
140                  * Handle first page in case it's not aligned
141                  */
142                 if (-p & (PAGE_SIZE - 1))
143                         sz = -p & (PAGE_SIZE - 1);
144                 else
145                         sz = PAGE_SIZE;
146
147                 sz = min_t(unsigned long, sz, count);
148
149                 /*
150                  * On ia64 if a page has been mapped somewhere as
151                  * uncached, then it must also be accessed uncached
152                  * by the kernel or data corruption may occur
153                  */
154                 ptr = xlate_dev_mem_ptr(p);
155
156                 if (copy_to_user(buf, ptr, sz))
157                         return -EFAULT;
158                 buf += sz;
159                 p += sz;
160                 count -= sz;
161                 read += sz;
162         }
163
164         *ppos += read;
165         return read;
166 }
167
168 static ssize_t write_mem(struct file * file, const char __user * buf, 
169                          size_t count, loff_t *ppos)
170 {
171         unsigned long p = *ppos;
172         ssize_t written, sz;
173         unsigned long copied;
174         void *ptr;
175
176         if (!valid_phys_addr_range(p, &count))
177                 return -EFAULT;
178
179         written = 0;
180
181 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
182         /* we don't have page 0 mapped on sparc and m68k.. */
183         if (p < PAGE_SIZE) {
184                 unsigned long sz = PAGE_SIZE - p;
185                 if (sz > count)
186                         sz = count;
187                 /* Hmm. Do something? */
188                 buf += sz;
189                 p += sz;
190                 count -= sz;
191                 written += sz;
192         }
193 #endif
194
195         while (count > 0) {
196                 /*
197                  * Handle first page in case it's not aligned
198                  */
199                 if (-p & (PAGE_SIZE - 1))
200                         sz = -p & (PAGE_SIZE - 1);
201                 else
202                         sz = PAGE_SIZE;
203
204                 sz = min_t(unsigned long, sz, count);
205
206                 /*
207                  * On ia64 if a page has been mapped somewhere as
208                  * uncached, then it must also be accessed uncached
209                  * by the kernel or data corruption may occur
210                  */
211                 ptr = xlate_dev_mem_ptr(p);
212
213                 copied = copy_from_user(ptr, buf, sz);
214                 if (copied) {
215                         ssize_t ret;
216
217                         ret = written + (sz - copied);
218                         if (ret)
219                                 return ret;
220                         return -EFAULT;
221                 }
222                 buf += sz;
223                 p += sz;
224                 count -= sz;
225                 written += sz;
226         }
227
228         *ppos += written;
229         return written;
230 }
231
232 static int mmap_mem(struct file * file, struct vm_area_struct * vma)
233 {
234 #if defined(__HAVE_PHYS_MEM_ACCESS_PROT)
235         unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
236
237         vma->vm_page_prot = phys_mem_access_prot(file, offset,
238                                                  vma->vm_end - vma->vm_start,
239                                                  vma->vm_page_prot);
240 #elif defined(pgprot_noncached)
241         unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
242         int uncached;
243
244         uncached = uncached_access(file, offset);
245         if (uncached)
246                 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
247 #endif
248
249         /* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */
250         if (remap_pfn_range(vma,
251                             vma->vm_start,
252                             vma->vm_pgoff,
253                             vma->vm_end-vma->vm_start,
254                             vma->vm_page_prot))
255                 return -EAGAIN;
256         return 0;
257 }
258
259 static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
260 {
261         unsigned long long val;
262         /*
263          * RED-PEN: on some architectures there is more mapped memory
264          * than available in mem_map which pfn_valid checks
265          * for. Perhaps should add a new macro here.
266          *
267          * RED-PEN: vmalloc is not supported right now.
268          */
269         if (!pfn_valid(vma->vm_pgoff))
270                 return -EIO;
271         val = (u64)vma->vm_pgoff << PAGE_SHIFT;
272         vma->vm_pgoff = __pa(val) >> PAGE_SHIFT;
273         return mmap_mem(file, vma);
274 }
275
276 extern long vread(char *buf, char *addr, unsigned long count);
277 extern long vwrite(char *buf, char *addr, unsigned long count);
278
279 /*
280  * This function reads the *virtual* memory as seen by the kernel.
281  */
282 static ssize_t read_kmem(struct file *file, char __user *buf, 
283                          size_t count, loff_t *ppos)
284 {
285         unsigned long p = *ppos;
286         ssize_t low_count, read, sz;
287         char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
288
289         read = 0;
290         if (p < (unsigned long) high_memory) {
291                 low_count = count;
292                 if (count > (unsigned long) high_memory - p)
293                         low_count = (unsigned long) high_memory - p;
294
295 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
296                 /* we don't have page 0 mapped on sparc and m68k.. */
297                 if (p < PAGE_SIZE && low_count > 0) {
298                         size_t tmp = PAGE_SIZE - p;
299                         if (tmp > low_count) tmp = low_count;
300                         if (clear_user(buf, tmp))
301                                 return -EFAULT;
302                         buf += tmp;
303                         p += tmp;
304                         read += tmp;
305                         low_count -= tmp;
306                         count -= tmp;
307                 }
308 #endif
309                 while (low_count > 0) {
310                         /*
311                          * Handle first page in case it's not aligned
312                          */
313                         if (-p & (PAGE_SIZE - 1))
314                                 sz = -p & (PAGE_SIZE - 1);
315                         else
316                                 sz = PAGE_SIZE;
317
318                         sz = min_t(unsigned long, sz, low_count);
319
320                         /*
321                          * On ia64 if a page has been mapped somewhere as
322                          * uncached, then it must also be accessed uncached
323                          * by the kernel or data corruption may occur
324                          */
325                         kbuf = xlate_dev_kmem_ptr((char *)p);
326
327                         if (copy_to_user(buf, kbuf, sz))
328                                 return -EFAULT;
329                         buf += sz;
330                         p += sz;
331                         read += sz;
332                         low_count -= sz;
333                         count -= sz;
334                 }
335         }
336
337         if (count > 0) {
338                 kbuf = (char *)__get_free_page(GFP_KERNEL);
339                 if (!kbuf)
340                         return -ENOMEM;
341                 while (count > 0) {
342                         int len = count;
343
344                         if (len > PAGE_SIZE)
345                                 len = PAGE_SIZE;
346                         len = vread(kbuf, (char *)p, len);
347                         if (!len)
348                                 break;
349                         if (copy_to_user(buf, kbuf, len)) {
350                                 free_page((unsigned long)kbuf);
351                                 return -EFAULT;
352                         }
353                         count -= len;
354                         buf += len;
355                         read += len;
356                         p += len;
357                 }
358                 free_page((unsigned long)kbuf);
359         }
360         *ppos = p;
361         return read;
362 }
363
364
365 static inline ssize_t
366 do_write_kmem(void *p, unsigned long realp, const char __user * buf,
367               size_t count, loff_t *ppos)
368 {
369         ssize_t written, sz;
370         unsigned long copied;
371
372         written = 0;
373 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
374         /* we don't have page 0 mapped on sparc and m68k.. */
375         if (realp < PAGE_SIZE) {
376                 unsigned long sz = PAGE_SIZE - realp;
377                 if (sz > count)
378                         sz = count;
379                 /* Hmm. Do something? */
380                 buf += sz;
381                 p += sz;
382                 realp += sz;
383                 count -= sz;
384                 written += sz;
385         }
386 #endif
387
388         while (count > 0) {
389                 char *ptr;
390                 /*
391                  * Handle first page in case it's not aligned
392                  */
393                 if (-realp & (PAGE_SIZE - 1))
394                         sz = -realp & (PAGE_SIZE - 1);
395                 else
396                         sz = PAGE_SIZE;
397
398                 sz = min_t(unsigned long, sz, count);
399
400                 /*
401                  * On ia64 if a page has been mapped somewhere as
402                  * uncached, then it must also be accessed uncached
403                  * by the kernel or data corruption may occur
404                  */
405                 ptr = xlate_dev_kmem_ptr(p);
406
407                 copied = copy_from_user(ptr, buf, sz);
408                 if (copied) {
409                         ssize_t ret;
410
411                         ret = written + (sz - copied);
412                         if (ret)
413                                 return ret;
414                         return -EFAULT;
415                 }
416                 buf += sz;
417                 p += sz;
418                 realp += sz;
419                 count -= sz;
420                 written += sz;
421         }
422
423         *ppos += written;
424         return written;
425 }
426
427
428 /*
429  * This function writes to the *virtual* memory as seen by the kernel.
430  */
431 static ssize_t write_kmem(struct file * file, const char __user * buf, 
432                           size_t count, loff_t *ppos)
433 {
434         unsigned long p = *ppos;
435         ssize_t wrote = 0;
436         ssize_t virtr = 0;
437         ssize_t written;
438         char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
439
440         if (p < (unsigned long) high_memory) {
441
442                 wrote = count;
443                 if (count > (unsigned long) high_memory - p)
444                         wrote = (unsigned long) high_memory - p;
445
446                 written = do_write_kmem((void*)p, p, buf, wrote, ppos);
447                 if (written != wrote)
448                         return written;
449                 wrote = written;
450                 p += wrote;
451                 buf += wrote;
452                 count -= wrote;
453         }
454
455         if (count > 0) {
456                 kbuf = (char *)__get_free_page(GFP_KERNEL);
457                 if (!kbuf)
458                         return wrote ? wrote : -ENOMEM;
459                 while (count > 0) {
460                         int len = count;
461
462                         if (len > PAGE_SIZE)
463                                 len = PAGE_SIZE;
464                         if (len) {
465                                 written = copy_from_user(kbuf, buf, len);
466                                 if (written) {
467                                         ssize_t ret;
468
469                                         free_page((unsigned long)kbuf);
470                                         ret = wrote + virtr + (len - written);
471                                         return ret ? ret : -EFAULT;
472                                 }
473                         }
474                         len = vwrite(kbuf, (char *)p, len);
475                         count -= len;
476                         buf += len;
477                         virtr += len;
478                         p += len;
479                 }
480                 free_page((unsigned long)kbuf);
481         }
482
483         *ppos = p;
484         return virtr + wrote;
485 }
486
487 #if defined(CONFIG_ISA) || !defined(__mc68000__)
488 static ssize_t read_port(struct file * file, char __user * buf,
489                          size_t count, loff_t *ppos)
490 {
491         unsigned long i = *ppos;
492         char __user *tmp = buf;
493
494         if (!access_ok(VERIFY_WRITE, buf, count))
495                 return -EFAULT; 
496         while (count-- > 0 && i < 65536) {
497                 if (__put_user(inb(i),tmp) < 0) 
498                         return -EFAULT;  
499                 i++;
500                 tmp++;
501         }
502         *ppos = i;
503         return tmp-buf;
504 }
505
506 static ssize_t write_port(struct file * file, const char __user * buf,
507                           size_t count, loff_t *ppos)
508 {
509         unsigned long i = *ppos;
510         const char __user * tmp = buf;
511
512         if (!access_ok(VERIFY_READ,buf,count))
513                 return -EFAULT;
514         while (count-- > 0 && i < 65536) {
515                 char c;
516                 if (__get_user(c, tmp)) 
517                         return -EFAULT; 
518                 outb(c,i);
519                 i++;
520                 tmp++;
521         }
522         *ppos = i;
523         return tmp-buf;
524 }
525 #endif
526
527 static ssize_t read_null(struct file * file, char __user * buf,
528                          size_t count, loff_t *ppos)
529 {
530         return 0;
531 }
532
533 static ssize_t write_null(struct file * file, const char __user * buf,
534                           size_t count, loff_t *ppos)
535 {
536         return count;
537 }
538
539 #ifdef CONFIG_MMU
540 /*
541  * For fun, we are using the MMU for this.
542  */
543 static inline size_t read_zero_pagealigned(char __user * buf, size_t size)
544 {
545         struct mm_struct *mm;
546         struct vm_area_struct * vma;
547         unsigned long addr=(unsigned long)buf;
548
549         mm = current->mm;
550         /* Oops, this was forgotten before. -ben */
551         down_read(&mm->mmap_sem);
552
553         /* For private mappings, just map in zero pages. */
554         for (vma = find_vma(mm, addr); vma; vma = vma->vm_next) {
555                 unsigned long count;
556
557                 if (vma->vm_start > addr || (vma->vm_flags & VM_WRITE) == 0)
558                         goto out_up;
559                 if (vma->vm_flags & (VM_SHARED | VM_HUGETLB))
560                         break;
561                 count = vma->vm_end - addr;
562                 if (count > size)
563                         count = size;
564
565                 zap_page_range(vma, addr, count, NULL);
566                 zeromap_page_range(vma, addr, count, PAGE_COPY);
567
568                 size -= count;
569                 buf += count;
570                 addr += count;
571                 if (size == 0)
572                         goto out_up;
573         }
574
575         up_read(&mm->mmap_sem);
576         
577         /* The shared case is hard. Let's do the conventional zeroing. */ 
578         do {
579                 unsigned long unwritten = clear_user(buf, PAGE_SIZE);
580                 if (unwritten)
581                         return size + unwritten - PAGE_SIZE;
582                 cond_resched();
583                 buf += PAGE_SIZE;
584                 size -= PAGE_SIZE;
585         } while (size);
586
587         return size;
588 out_up:
589         up_read(&mm->mmap_sem);
590         return size;
591 }
592
593 static ssize_t read_zero(struct file * file, char __user * buf, 
594                          size_t count, loff_t *ppos)
595 {
596         unsigned long left, unwritten, written = 0;
597
598         if (!count)
599                 return 0;
600
601         if (!access_ok(VERIFY_WRITE, buf, count))
602                 return -EFAULT;
603
604         left = count;
605
606         /* do we want to be clever? Arbitrary cut-off */
607         if (count >= PAGE_SIZE*4) {
608                 unsigned long partial;
609
610                 /* How much left of the page? */
611                 partial = (PAGE_SIZE-1) & -(unsigned long) buf;
612                 unwritten = clear_user(buf, partial);
613                 written = partial - unwritten;
614                 if (unwritten)
615                         goto out;
616                 left -= partial;
617                 buf += partial;
618                 unwritten = read_zero_pagealigned(buf, left & PAGE_MASK);
619                 written += (left & PAGE_MASK) - unwritten;
620                 if (unwritten)
621                         goto out;
622                 buf += left & PAGE_MASK;
623                 left &= ~PAGE_MASK;
624         }
625         unwritten = clear_user(buf, left);
626         written += left - unwritten;
627 out:
628         return written ? written : -EFAULT;
629 }
630
631 static int mmap_zero(struct file * file, struct vm_area_struct * vma)
632 {
633         if (vma->vm_flags & VM_SHARED)
634                 return shmem_zero_setup(vma);
635         if (zeromap_page_range(vma, vma->vm_start, vma->vm_end - vma->vm_start, vma->vm_page_prot))
636                 return -EAGAIN;
637         return 0;
638 }
639 #else /* CONFIG_MMU */
640 static ssize_t read_zero(struct file * file, char * buf, 
641                          size_t count, loff_t *ppos)
642 {
643         size_t todo = count;
644
645         while (todo) {
646                 size_t chunk = todo;
647
648                 if (chunk > 4096)
649                         chunk = 4096;   /* Just for latency reasons */
650                 if (clear_user(buf, chunk))
651                         return -EFAULT;
652                 buf += chunk;
653                 todo -= chunk;
654                 cond_resched();
655         }
656         return count;
657 }
658
659 static int mmap_zero(struct file * file, struct vm_area_struct * vma)
660 {
661         return -ENOSYS;
662 }
663 #endif /* CONFIG_MMU */
664
665 static ssize_t write_full(struct file * file, const char __user * buf,
666                           size_t count, loff_t *ppos)
667 {
668         return -ENOSPC;
669 }
670
671 /*
672  * Special lseek() function for /dev/null and /dev/zero.  Most notably, you
673  * can fopen() both devices with "a" now.  This was previously impossible.
674  * -- SRB.
675  */
676
677 static loff_t null_lseek(struct file * file, loff_t offset, int orig)
678 {
679         return file->f_pos = 0;
680 }
681
682 /*
683  * The memory devices use the full 32/64 bits of the offset, and so we cannot
684  * check against negative addresses: they are ok. The return value is weird,
685  * though, in that case (0).
686  *
687  * also note that seeking relative to the "end of file" isn't supported:
688  * it has no meaning, so it returns -EINVAL.
689  */
690 static loff_t memory_lseek(struct file * file, loff_t offset, int orig)
691 {
692         loff_t ret;
693
694         down(&file->f_dentry->d_inode->i_sem);
695         switch (orig) {
696                 case 0:
697                         file->f_pos = offset;
698                         ret = file->f_pos;
699                         force_successful_syscall_return();
700                         break;
701                 case 1:
702                         file->f_pos += offset;
703                         ret = file->f_pos;
704                         force_successful_syscall_return();
705                         break;
706                 default:
707                         ret = -EINVAL;
708         }
709         up(&file->f_dentry->d_inode->i_sem);
710         return ret;
711 }
712
713 static int open_port(struct inode * inode, struct file * filp)
714 {
715         return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
716 }
717
718 #define zero_lseek      null_lseek
719 #define full_lseek      null_lseek
720 #define write_zero      write_null
721 #define read_full       read_zero
722 #define open_mem        open_port
723 #define open_kmem       open_mem
724
725 static struct file_operations mem_fops = {
726         .llseek         = memory_lseek,
727         .read           = read_mem,
728         .write          = write_mem,
729         .mmap           = mmap_mem,
730         .open           = open_mem,
731 };
732
733 static struct file_operations kmem_fops = {
734         .llseek         = memory_lseek,
735         .read           = read_kmem,
736         .write          = write_kmem,
737         .mmap           = mmap_kmem,
738         .open           = open_kmem,
739 };
740
741 static struct file_operations null_fops = {
742         .llseek         = null_lseek,
743         .read           = read_null,
744         .write          = write_null,
745 };
746
747 #if defined(CONFIG_ISA) || !defined(__mc68000__)
748 static struct file_operations port_fops = {
749         .llseek         = memory_lseek,
750         .read           = read_port,
751         .write          = write_port,
752         .open           = open_port,
753 };
754 #endif
755
756 static struct file_operations zero_fops = {
757         .llseek         = zero_lseek,
758         .read           = read_zero,
759         .write          = write_zero,
760         .mmap           = mmap_zero,
761 };
762
763 static struct backing_dev_info zero_bdi = {
764         .capabilities   = BDI_CAP_MAP_COPY,
765 };
766
767 static struct file_operations full_fops = {
768         .llseek         = full_lseek,
769         .read           = read_full,
770         .write          = write_full,
771 };
772
773 static ssize_t kmsg_write(struct file * file, const char __user * buf,
774                           size_t count, loff_t *ppos)
775 {
776         char *tmp;
777         int ret;
778
779         tmp = kmalloc(count + 1, GFP_KERNEL);
780         if (tmp == NULL)
781                 return -ENOMEM;
782         ret = -EFAULT;
783         if (!copy_from_user(tmp, buf, count)) {
784                 tmp[count] = 0;
785                 ret = printk("%s", tmp);
786         }
787         kfree(tmp);
788         return ret;
789 }
790
791 static struct file_operations kmsg_fops = {
792         .write =        kmsg_write,
793 };
794
795 static int memory_open(struct inode * inode, struct file * filp)
796 {
797         switch (iminor(inode)) {
798                 case 1:
799                         filp->f_op = &mem_fops;
800                         break;
801                 case 2:
802                         filp->f_op = &kmem_fops;
803                         break;
804                 case 3:
805                         filp->f_op = &null_fops;
806                         break;
807 #if defined(CONFIG_ISA) || !defined(__mc68000__)
808                 case 4:
809                         filp->f_op = &port_fops;
810                         break;
811 #endif
812                 case 5:
813                         filp->f_mapping->backing_dev_info = &zero_bdi;
814                         filp->f_op = &zero_fops;
815                         break;
816                 case 7:
817                         filp->f_op = &full_fops;
818                         break;
819                 case 8:
820                         filp->f_op = &random_fops;
821                         break;
822                 case 9:
823                         filp->f_op = &urandom_fops;
824                         break;
825                 case 11:
826                         filp->f_op = &kmsg_fops;
827                         break;
828                 default:
829                         return -ENXIO;
830         }
831         if (filp->f_op && filp->f_op->open)
832                 return filp->f_op->open(inode,filp);
833         return 0;
834 }
835
836 static struct file_operations memory_fops = {
837         .open           = memory_open,  /* just a selector for the real open */
838 };
839
840 static const struct {
841         unsigned int            minor;
842         char                    *name;
843         umode_t                 mode;
844         struct file_operations  *fops;
845 } devlist[] = { /* list of minor devices */
846         {1, "mem",     S_IRUSR | S_IWUSR | S_IRGRP, &mem_fops},
847         {2, "kmem",    S_IRUSR | S_IWUSR | S_IRGRP, &kmem_fops},
848         {3, "null",    S_IRUGO | S_IWUGO,           &null_fops},
849 #if defined(CONFIG_ISA) || !defined(__mc68000__)
850         {4, "port",    S_IRUSR | S_IWUSR | S_IRGRP, &port_fops},
851 #endif
852         {5, "zero",    S_IRUGO | S_IWUGO,           &zero_fops},
853         {7, "full",    S_IRUGO | S_IWUGO,           &full_fops},
854         {8, "random",  S_IRUGO | S_IWUSR,           &random_fops},
855         {9, "urandom", S_IRUGO | S_IWUSR,           &urandom_fops},
856         {11,"kmsg",    S_IRUGO | S_IWUSR,           &kmsg_fops},
857 };
858
859 static struct class_simple *mem_class;
860
861 static int __init chr_dev_init(void)
862 {
863         int i;
864
865         if (register_chrdev(MEM_MAJOR,"mem",&memory_fops))
866                 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
867
868         mem_class = class_simple_create(THIS_MODULE, "mem");
869         for (i = 0; i < ARRAY_SIZE(devlist); i++) {
870                 class_simple_device_add(mem_class,
871                                         MKDEV(MEM_MAJOR, devlist[i].minor),
872                                         NULL, devlist[i].name);
873                 devfs_mk_cdev(MKDEV(MEM_MAJOR, devlist[i].minor),
874                                 S_IFCHR | devlist[i].mode, devlist[i].name);
875         }
876         
877         return 0;
878 }
879
880 fs_initcall(chr_dev_init);