[PATCH] kmsg_write: don't return printk return value
[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/highmem.h>
27 #include <linux/crash_dump.h>
28 #include <linux/backing-dev.h>
29 #include <linux/bootmem.h>
30
31 #include <asm/uaccess.h>
32 #include <asm/io.h>
33
34 #ifdef CONFIG_IA64
35 # include <linux/efi.h>
36 #endif
37
38 /*
39  * Architectures vary in how they handle caching for addresses
40  * outside of main memory.
41  *
42  */
43 static inline int uncached_access(struct file *file, unsigned long addr)
44 {
45 #if defined(__i386__)
46         /*
47          * On the PPro and successors, the MTRRs are used to set
48          * memory types for physical addresses outside main memory,
49          * so blindly setting PCD or PWT on those pages is wrong.
50          * For Pentiums and earlier, the surround logic should disable
51          * caching for the high addresses through the KEN pin, but
52          * we maintain the tradition of paranoia in this code.
53          */
54         if (file->f_flags & O_SYNC)
55                 return 1;
56         return !( test_bit(X86_FEATURE_MTRR, boot_cpu_data.x86_capability) ||
57                   test_bit(X86_FEATURE_K6_MTRR, boot_cpu_data.x86_capability) ||
58                   test_bit(X86_FEATURE_CYRIX_ARR, boot_cpu_data.x86_capability) ||
59                   test_bit(X86_FEATURE_CENTAUR_MCR, boot_cpu_data.x86_capability) )
60           && addr >= __pa(high_memory);
61 #elif defined(__x86_64__)
62         /* 
63          * This is broken because it can generate memory type aliases,
64          * which can cause cache corruptions
65          * But it is only available for root and we have to be bug-to-bug
66          * compatible with i386.
67          */
68         if (file->f_flags & O_SYNC)
69                 return 1;
70         /* same behaviour as i386. PAT always set to cached and MTRRs control the
71            caching behaviour. 
72            Hopefully a full PAT implementation will fix that soon. */      
73         return 0;
74 #elif defined(CONFIG_IA64)
75         /*
76          * On ia64, we ignore O_SYNC because we cannot tolerate memory attribute aliases.
77          */
78         return !(efi_mem_attributes(addr) & EFI_MEMORY_WB);
79 #else
80         /*
81          * Accessing memory above the top the kernel knows about or through a file pointer
82          * that was marked O_SYNC will be done non-cached.
83          */
84         if (file->f_flags & O_SYNC)
85                 return 1;
86         return addr >= __pa(high_memory);
87 #endif
88 }
89
90 #ifndef ARCH_HAS_VALID_PHYS_ADDR_RANGE
91 static inline int valid_phys_addr_range(unsigned long addr, size_t *count)
92 {
93         unsigned long end_mem;
94
95         end_mem = __pa(high_memory);
96         if (addr >= end_mem)
97                 return 0;
98
99         if (*count > end_mem - addr)
100                 *count = end_mem - addr;
101
102         return 1;
103 }
104 #endif
105
106 /*
107  * This funcion reads the *physical* memory. The f_pos points directly to the 
108  * memory location. 
109  */
110 static ssize_t read_mem(struct file * file, char __user * buf,
111                         size_t count, loff_t *ppos)
112 {
113         unsigned long p = *ppos;
114         ssize_t read, sz;
115         char *ptr;
116
117         if (!valid_phys_addr_range(p, &count))
118                 return -EFAULT;
119         read = 0;
120 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
121         /* we don't have page 0 mapped on sparc and m68k.. */
122         if (p < PAGE_SIZE) {
123                 sz = PAGE_SIZE - p;
124                 if (sz > count) 
125                         sz = count; 
126                 if (sz > 0) {
127                         if (clear_user(buf, sz))
128                                 return -EFAULT;
129                         buf += sz; 
130                         p += sz; 
131                         count -= sz; 
132                         read += sz; 
133                 }
134         }
135 #endif
136
137         while (count > 0) {
138                 /*
139                  * Handle first page in case it's not aligned
140                  */
141                 if (-p & (PAGE_SIZE - 1))
142                         sz = -p & (PAGE_SIZE - 1);
143                 else
144                         sz = PAGE_SIZE;
145
146                 sz = min_t(unsigned long, sz, count);
147
148                 /*
149                  * On ia64 if a page has been mapped somewhere as
150                  * uncached, then it must also be accessed uncached
151                  * by the kernel or data corruption may occur
152                  */
153                 ptr = xlate_dev_mem_ptr(p);
154
155                 if (copy_to_user(buf, ptr, sz))
156                         return -EFAULT;
157                 buf += sz;
158                 p += sz;
159                 count -= sz;
160                 read += sz;
161         }
162
163         *ppos += read;
164         return read;
165 }
166
167 static ssize_t write_mem(struct file * file, const char __user * buf, 
168                          size_t count, loff_t *ppos)
169 {
170         unsigned long p = *ppos;
171         ssize_t written, sz;
172         unsigned long copied;
173         void *ptr;
174
175         if (!valid_phys_addr_range(p, &count))
176                 return -EFAULT;
177
178         written = 0;
179
180 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
181         /* we don't have page 0 mapped on sparc and m68k.. */
182         if (p < PAGE_SIZE) {
183                 unsigned long sz = PAGE_SIZE - p;
184                 if (sz > count)
185                         sz = count;
186                 /* Hmm. Do something? */
187                 buf += sz;
188                 p += sz;
189                 count -= sz;
190                 written += sz;
191         }
192 #endif
193
194         while (count > 0) {
195                 /*
196                  * Handle first page in case it's not aligned
197                  */
198                 if (-p & (PAGE_SIZE - 1))
199                         sz = -p & (PAGE_SIZE - 1);
200                 else
201                         sz = PAGE_SIZE;
202
203                 sz = min_t(unsigned long, sz, count);
204
205                 /*
206                  * On ia64 if a page has been mapped somewhere as
207                  * uncached, then it must also be accessed uncached
208                  * by the kernel or data corruption may occur
209                  */
210                 ptr = xlate_dev_mem_ptr(p);
211
212                 copied = copy_from_user(ptr, buf, sz);
213                 if (copied) {
214                         ssize_t ret;
215
216                         ret = written + (sz - copied);
217                         if (ret)
218                                 return ret;
219                         return -EFAULT;
220                 }
221                 buf += sz;
222                 p += sz;
223                 count -= sz;
224                 written += sz;
225         }
226
227         *ppos += written;
228         return written;
229 }
230
231 static int mmap_mem(struct file * file, struct vm_area_struct * vma)
232 {
233 #if defined(__HAVE_PHYS_MEM_ACCESS_PROT)
234         vma->vm_page_prot = phys_mem_access_prot(file, vma->vm_pgoff,
235                                                  vma->vm_end - vma->vm_start,
236                                                  vma->vm_page_prot);
237 #elif defined(pgprot_noncached)
238         unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
239         int uncached;
240
241         uncached = uncached_access(file, offset);
242         if (uncached)
243                 vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
244 #endif
245
246         /* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */
247         if (remap_pfn_range(vma,
248                             vma->vm_start,
249                             vma->vm_pgoff,
250                             vma->vm_end-vma->vm_start,
251                             vma->vm_page_prot))
252                 return -EAGAIN;
253         return 0;
254 }
255
256 static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
257 {
258         unsigned long pfn;
259
260         /* Turn a kernel-virtual address into a physical page frame */
261         pfn = __pa((u64)vma->vm_pgoff << PAGE_SHIFT) >> PAGE_SHIFT;
262
263         /*
264          * RED-PEN: on some architectures there is more mapped memory
265          * than available in mem_map which pfn_valid checks
266          * for. Perhaps should add a new macro here.
267          *
268          * RED-PEN: vmalloc is not supported right now.
269          */
270         if (!pfn_valid(pfn))
271                 return -EIO;
272
273         vma->vm_pgoff = pfn;
274         return mmap_mem(file, vma);
275 }
276
277 #ifdef CONFIG_CRASH_DUMP
278 /*
279  * Read memory corresponding to the old kernel.
280  */
281 static ssize_t read_oldmem(struct file *file, char __user *buf,
282                                 size_t count, loff_t *ppos)
283 {
284         unsigned long pfn, offset;
285         size_t read = 0, csize;
286         int rc = 0;
287
288         while (count) {
289                 pfn = *ppos / PAGE_SIZE;
290                 if (pfn > saved_max_pfn)
291                         return read;
292
293                 offset = (unsigned long)(*ppos % PAGE_SIZE);
294                 if (count > PAGE_SIZE - offset)
295                         csize = PAGE_SIZE - offset;
296                 else
297                         csize = count;
298
299                 rc = copy_oldmem_page(pfn, buf, csize, offset, 1);
300                 if (rc < 0)
301                         return rc;
302                 buf += csize;
303                 *ppos += csize;
304                 read += csize;
305                 count -= csize;
306         }
307         return read;
308 }
309 #endif
310
311 extern long vread(char *buf, char *addr, unsigned long count);
312 extern long vwrite(char *buf, char *addr, unsigned long count);
313
314 /*
315  * This function reads the *virtual* memory as seen by the kernel.
316  */
317 static ssize_t read_kmem(struct file *file, char __user *buf, 
318                          size_t count, loff_t *ppos)
319 {
320         unsigned long p = *ppos;
321         ssize_t low_count, read, sz;
322         char * kbuf; /* k-addr because vread() takes vmlist_lock rwlock */
323
324         read = 0;
325         if (p < (unsigned long) high_memory) {
326                 low_count = count;
327                 if (count > (unsigned long) high_memory - p)
328                         low_count = (unsigned long) high_memory - p;
329
330 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
331                 /* we don't have page 0 mapped on sparc and m68k.. */
332                 if (p < PAGE_SIZE && low_count > 0) {
333                         size_t tmp = PAGE_SIZE - p;
334                         if (tmp > low_count) tmp = low_count;
335                         if (clear_user(buf, tmp))
336                                 return -EFAULT;
337                         buf += tmp;
338                         p += tmp;
339                         read += tmp;
340                         low_count -= tmp;
341                         count -= tmp;
342                 }
343 #endif
344                 while (low_count > 0) {
345                         /*
346                          * Handle first page in case it's not aligned
347                          */
348                         if (-p & (PAGE_SIZE - 1))
349                                 sz = -p & (PAGE_SIZE - 1);
350                         else
351                                 sz = PAGE_SIZE;
352
353                         sz = min_t(unsigned long, sz, low_count);
354
355                         /*
356                          * On ia64 if a page has been mapped somewhere as
357                          * uncached, then it must also be accessed uncached
358                          * by the kernel or data corruption may occur
359                          */
360                         kbuf = xlate_dev_kmem_ptr((char *)p);
361
362                         if (copy_to_user(buf, kbuf, sz))
363                                 return -EFAULT;
364                         buf += sz;
365                         p += sz;
366                         read += sz;
367                         low_count -= sz;
368                         count -= sz;
369                 }
370         }
371
372         if (count > 0) {
373                 kbuf = (char *)__get_free_page(GFP_KERNEL);
374                 if (!kbuf)
375                         return -ENOMEM;
376                 while (count > 0) {
377                         int len = count;
378
379                         if (len > PAGE_SIZE)
380                                 len = PAGE_SIZE;
381                         len = vread(kbuf, (char *)p, len);
382                         if (!len)
383                                 break;
384                         if (copy_to_user(buf, kbuf, len)) {
385                                 free_page((unsigned long)kbuf);
386                                 return -EFAULT;
387                         }
388                         count -= len;
389                         buf += len;
390                         read += len;
391                         p += len;
392                 }
393                 free_page((unsigned long)kbuf);
394         }
395         *ppos = p;
396         return read;
397 }
398
399
400 static inline ssize_t
401 do_write_kmem(void *p, unsigned long realp, const char __user * buf,
402               size_t count, loff_t *ppos)
403 {
404         ssize_t written, sz;
405         unsigned long copied;
406
407         written = 0;
408 #ifdef __ARCH_HAS_NO_PAGE_ZERO_MAPPED
409         /* we don't have page 0 mapped on sparc and m68k.. */
410         if (realp < PAGE_SIZE) {
411                 unsigned long sz = PAGE_SIZE - realp;
412                 if (sz > count)
413                         sz = count;
414                 /* Hmm. Do something? */
415                 buf += sz;
416                 p += sz;
417                 realp += sz;
418                 count -= sz;
419                 written += sz;
420         }
421 #endif
422
423         while (count > 0) {
424                 char *ptr;
425                 /*
426                  * Handle first page in case it's not aligned
427                  */
428                 if (-realp & (PAGE_SIZE - 1))
429                         sz = -realp & (PAGE_SIZE - 1);
430                 else
431                         sz = PAGE_SIZE;
432
433                 sz = min_t(unsigned long, sz, count);
434
435                 /*
436                  * On ia64 if a page has been mapped somewhere as
437                  * uncached, then it must also be accessed uncached
438                  * by the kernel or data corruption may occur
439                  */
440                 ptr = xlate_dev_kmem_ptr(p);
441
442                 copied = copy_from_user(ptr, buf, sz);
443                 if (copied) {
444                         ssize_t ret;
445
446                         ret = written + (sz - copied);
447                         if (ret)
448                                 return ret;
449                         return -EFAULT;
450                 }
451                 buf += sz;
452                 p += sz;
453                 realp += sz;
454                 count -= sz;
455                 written += sz;
456         }
457
458         *ppos += written;
459         return written;
460 }
461
462
463 /*
464  * This function writes to the *virtual* memory as seen by the kernel.
465  */
466 static ssize_t write_kmem(struct file * file, const char __user * buf, 
467                           size_t count, loff_t *ppos)
468 {
469         unsigned long p = *ppos;
470         ssize_t wrote = 0;
471         ssize_t virtr = 0;
472         ssize_t written;
473         char * kbuf; /* k-addr because vwrite() takes vmlist_lock rwlock */
474
475         if (p < (unsigned long) high_memory) {
476
477                 wrote = count;
478                 if (count > (unsigned long) high_memory - p)
479                         wrote = (unsigned long) high_memory - p;
480
481                 written = do_write_kmem((void*)p, p, buf, wrote, ppos);
482                 if (written != wrote)
483                         return written;
484                 wrote = written;
485                 p += wrote;
486                 buf += wrote;
487                 count -= wrote;
488         }
489
490         if (count > 0) {
491                 kbuf = (char *)__get_free_page(GFP_KERNEL);
492                 if (!kbuf)
493                         return wrote ? wrote : -ENOMEM;
494                 while (count > 0) {
495                         int len = count;
496
497                         if (len > PAGE_SIZE)
498                                 len = PAGE_SIZE;
499                         if (len) {
500                                 written = copy_from_user(kbuf, buf, len);
501                                 if (written) {
502                                         ssize_t ret;
503
504                                         free_page((unsigned long)kbuf);
505                                         ret = wrote + virtr + (len - written);
506                                         return ret ? ret : -EFAULT;
507                                 }
508                         }
509                         len = vwrite(kbuf, (char *)p, len);
510                         count -= len;
511                         buf += len;
512                         virtr += len;
513                         p += len;
514                 }
515                 free_page((unsigned long)kbuf);
516         }
517
518         *ppos = p;
519         return virtr + wrote;
520 }
521
522 #if (defined(CONFIG_ISA) || !defined(__mc68000__)) && (!defined(CONFIG_PPC_ISERIES) || defined(CONFIG_PCI))
523 static ssize_t read_port(struct file * file, char __user * buf,
524                          size_t count, loff_t *ppos)
525 {
526         unsigned long i = *ppos;
527         char __user *tmp = buf;
528
529         if (!access_ok(VERIFY_WRITE, buf, count))
530                 return -EFAULT; 
531         while (count-- > 0 && i < 65536) {
532                 if (__put_user(inb(i),tmp) < 0) 
533                         return -EFAULT;  
534                 i++;
535                 tmp++;
536         }
537         *ppos = i;
538         return tmp-buf;
539 }
540
541 static ssize_t write_port(struct file * file, const char __user * buf,
542                           size_t count, loff_t *ppos)
543 {
544         unsigned long i = *ppos;
545         const char __user * tmp = buf;
546
547         if (!access_ok(VERIFY_READ,buf,count))
548                 return -EFAULT;
549         while (count-- > 0 && i < 65536) {
550                 char c;
551                 if (__get_user(c, tmp)) 
552                         return -EFAULT; 
553                 outb(c,i);
554                 i++;
555                 tmp++;
556         }
557         *ppos = i;
558         return tmp-buf;
559 }
560 #endif
561
562 static ssize_t read_null(struct file * file, char __user * buf,
563                          size_t count, loff_t *ppos)
564 {
565         return 0;
566 }
567
568 static ssize_t write_null(struct file * file, const char __user * buf,
569                           size_t count, loff_t *ppos)
570 {
571         return count;
572 }
573
574 #ifdef CONFIG_MMU
575 /*
576  * For fun, we are using the MMU for this.
577  */
578 static inline size_t read_zero_pagealigned(char __user * buf, size_t size)
579 {
580         struct mm_struct *mm;
581         struct vm_area_struct * vma;
582         unsigned long addr=(unsigned long)buf;
583
584         mm = current->mm;
585         /* Oops, this was forgotten before. -ben */
586         down_read(&mm->mmap_sem);
587
588         /* For private mappings, just map in zero pages. */
589         for (vma = find_vma(mm, addr); vma; vma = vma->vm_next) {
590                 unsigned long count;
591
592                 if (vma->vm_start > addr || (vma->vm_flags & VM_WRITE) == 0)
593                         goto out_up;
594                 if (vma->vm_flags & (VM_SHARED | VM_HUGETLB))
595                         break;
596                 count = vma->vm_end - addr;
597                 if (count > size)
598                         count = size;
599
600                 zap_page_range(vma, addr, count, NULL);
601                 zeromap_page_range(vma, addr, count, PAGE_COPY);
602
603                 size -= count;
604                 buf += count;
605                 addr += count;
606                 if (size == 0)
607                         goto out_up;
608         }
609
610         up_read(&mm->mmap_sem);
611         
612         /* The shared case is hard. Let's do the conventional zeroing. */ 
613         do {
614                 unsigned long unwritten = clear_user(buf, PAGE_SIZE);
615                 if (unwritten)
616                         return size + unwritten - PAGE_SIZE;
617                 cond_resched();
618                 buf += PAGE_SIZE;
619                 size -= PAGE_SIZE;
620         } while (size);
621
622         return size;
623 out_up:
624         up_read(&mm->mmap_sem);
625         return size;
626 }
627
628 static ssize_t read_zero(struct file * file, char __user * buf, 
629                          size_t count, loff_t *ppos)
630 {
631         unsigned long left, unwritten, written = 0;
632
633         if (!count)
634                 return 0;
635
636         if (!access_ok(VERIFY_WRITE, buf, count))
637                 return -EFAULT;
638
639         left = count;
640
641         /* do we want to be clever? Arbitrary cut-off */
642         if (count >= PAGE_SIZE*4) {
643                 unsigned long partial;
644
645                 /* How much left of the page? */
646                 partial = (PAGE_SIZE-1) & -(unsigned long) buf;
647                 unwritten = clear_user(buf, partial);
648                 written = partial - unwritten;
649                 if (unwritten)
650                         goto out;
651                 left -= partial;
652                 buf += partial;
653                 unwritten = read_zero_pagealigned(buf, left & PAGE_MASK);
654                 written += (left & PAGE_MASK) - unwritten;
655                 if (unwritten)
656                         goto out;
657                 buf += left & PAGE_MASK;
658                 left &= ~PAGE_MASK;
659         }
660         unwritten = clear_user(buf, left);
661         written += left - unwritten;
662 out:
663         return written ? written : -EFAULT;
664 }
665
666 static int mmap_zero(struct file * file, struct vm_area_struct * vma)
667 {
668         if (vma->vm_flags & VM_SHARED)
669                 return shmem_zero_setup(vma);
670         if (zeromap_page_range(vma, vma->vm_start, vma->vm_end - vma->vm_start, vma->vm_page_prot))
671                 return -EAGAIN;
672         return 0;
673 }
674 #else /* CONFIG_MMU */
675 static ssize_t read_zero(struct file * file, char * buf, 
676                          size_t count, loff_t *ppos)
677 {
678         size_t todo = count;
679
680         while (todo) {
681                 size_t chunk = todo;
682
683                 if (chunk > 4096)
684                         chunk = 4096;   /* Just for latency reasons */
685                 if (clear_user(buf, chunk))
686                         return -EFAULT;
687                 buf += chunk;
688                 todo -= chunk;
689                 cond_resched();
690         }
691         return count;
692 }
693
694 static int mmap_zero(struct file * file, struct vm_area_struct * vma)
695 {
696         return -ENOSYS;
697 }
698 #endif /* CONFIG_MMU */
699
700 static ssize_t write_full(struct file * file, const char __user * buf,
701                           size_t count, loff_t *ppos)
702 {
703         return -ENOSPC;
704 }
705
706 /*
707  * Special lseek() function for /dev/null and /dev/zero.  Most notably, you
708  * can fopen() both devices with "a" now.  This was previously impossible.
709  * -- SRB.
710  */
711
712 static loff_t null_lseek(struct file * file, loff_t offset, int orig)
713 {
714         return file->f_pos = 0;
715 }
716
717 /*
718  * The memory devices use the full 32/64 bits of the offset, and so we cannot
719  * check against negative addresses: they are ok. The return value is weird,
720  * though, in that case (0).
721  *
722  * also note that seeking relative to the "end of file" isn't supported:
723  * it has no meaning, so it returns -EINVAL.
724  */
725 static loff_t memory_lseek(struct file * file, loff_t offset, int orig)
726 {
727         loff_t ret;
728
729         down(&file->f_dentry->d_inode->i_sem);
730         switch (orig) {
731                 case 0:
732                         file->f_pos = offset;
733                         ret = file->f_pos;
734                         force_successful_syscall_return();
735                         break;
736                 case 1:
737                         file->f_pos += offset;
738                         ret = file->f_pos;
739                         force_successful_syscall_return();
740                         break;
741                 default:
742                         ret = -EINVAL;
743         }
744         up(&file->f_dentry->d_inode->i_sem);
745         return ret;
746 }
747
748 static int open_port(struct inode * inode, struct file * filp)
749 {
750         return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
751 }
752
753 #define zero_lseek      null_lseek
754 #define full_lseek      null_lseek
755 #define write_zero      write_null
756 #define read_full       read_zero
757 #define open_mem        open_port
758 #define open_kmem       open_mem
759 #define open_oldmem     open_mem
760
761 static struct file_operations mem_fops = {
762         .llseek         = memory_lseek,
763         .read           = read_mem,
764         .write          = write_mem,
765         .mmap           = mmap_mem,
766         .open           = open_mem,
767 };
768
769 static struct file_operations kmem_fops = {
770         .llseek         = memory_lseek,
771         .read           = read_kmem,
772         .write          = write_kmem,
773         .mmap           = mmap_kmem,
774         .open           = open_kmem,
775 };
776
777 static struct file_operations null_fops = {
778         .llseek         = null_lseek,
779         .read           = read_null,
780         .write          = write_null,
781 };
782
783 #if (defined(CONFIG_ISA) || !defined(__mc68000__)) && (!defined(CONFIG_PPC_ISERIES) || defined(CONFIG_PCI))
784 static struct file_operations port_fops = {
785         .llseek         = memory_lseek,
786         .read           = read_port,
787         .write          = write_port,
788         .open           = open_port,
789 };
790 #endif
791
792 static struct file_operations zero_fops = {
793         .llseek         = zero_lseek,
794         .read           = read_zero,
795         .write          = write_zero,
796         .mmap           = mmap_zero,
797 };
798
799 static struct backing_dev_info zero_bdi = {
800         .capabilities   = BDI_CAP_MAP_COPY,
801 };
802
803 static struct file_operations full_fops = {
804         .llseek         = full_lseek,
805         .read           = read_full,
806         .write          = write_full,
807 };
808
809 #ifdef CONFIG_CRASH_DUMP
810 static struct file_operations oldmem_fops = {
811         .read   = read_oldmem,
812         .open   = open_oldmem,
813 };
814 #endif
815
816 static ssize_t kmsg_write(struct file * file, const char __user * buf,
817                           size_t count, loff_t *ppos)
818 {
819         char *tmp;
820         ssize_t ret;
821
822         tmp = kmalloc(count + 1, GFP_KERNEL);
823         if (tmp == NULL)
824                 return -ENOMEM;
825         ret = -EFAULT;
826         if (!copy_from_user(tmp, buf, count)) {
827                 tmp[count] = 0;
828                 ret = printk("%s", tmp);
829                 if (ret > count)
830                         /* printk can add a prefix */
831                         ret = count;
832         }
833         kfree(tmp);
834         return ret;
835 }
836
837 static struct file_operations kmsg_fops = {
838         .write =        kmsg_write,
839 };
840
841 static int memory_open(struct inode * inode, struct file * filp)
842 {
843         switch (iminor(inode)) {
844                 case 1:
845                         filp->f_op = &mem_fops;
846                         break;
847                 case 2:
848                         filp->f_op = &kmem_fops;
849                         break;
850                 case 3:
851                         filp->f_op = &null_fops;
852                         break;
853 #if (defined(CONFIG_ISA) || !defined(__mc68000__)) && (!defined(CONFIG_PPC_ISERIES) || defined(CONFIG_PCI))
854                 case 4:
855                         filp->f_op = &port_fops;
856                         break;
857 #endif
858                 case 5:
859                         filp->f_mapping->backing_dev_info = &zero_bdi;
860                         filp->f_op = &zero_fops;
861                         break;
862                 case 7:
863                         filp->f_op = &full_fops;
864                         break;
865                 case 8:
866                         filp->f_op = &random_fops;
867                         break;
868                 case 9:
869                         filp->f_op = &urandom_fops;
870                         break;
871                 case 11:
872                         filp->f_op = &kmsg_fops;
873                         break;
874 #ifdef CONFIG_CRASH_DUMP
875                 case 12:
876                         filp->f_op = &oldmem_fops;
877                         break;
878 #endif
879                 default:
880                         return -ENXIO;
881         }
882         if (filp->f_op && filp->f_op->open)
883                 return filp->f_op->open(inode,filp);
884         return 0;
885 }
886
887 static struct file_operations memory_fops = {
888         .open           = memory_open,  /* just a selector for the real open */
889 };
890
891 static const struct {
892         unsigned int            minor;
893         char                    *name;
894         umode_t                 mode;
895         struct file_operations  *fops;
896 } devlist[] = { /* list of minor devices */
897         {1, "mem",     S_IRUSR | S_IWUSR | S_IRGRP, &mem_fops},
898         {2, "kmem",    S_IRUSR | S_IWUSR | S_IRGRP, &kmem_fops},
899         {3, "null",    S_IRUGO | S_IWUGO,           &null_fops},
900 #if (defined(CONFIG_ISA) || !defined(__mc68000__)) && (!defined(CONFIG_PPC_ISERIES) || defined(CONFIG_PCI))
901         {4, "port",    S_IRUSR | S_IWUSR | S_IRGRP, &port_fops},
902 #endif
903         {5, "zero",    S_IRUGO | S_IWUGO,           &zero_fops},
904         {7, "full",    S_IRUGO | S_IWUGO,           &full_fops},
905         {8, "random",  S_IRUGO | S_IWUSR,           &random_fops},
906         {9, "urandom", S_IRUGO | S_IWUSR,           &urandom_fops},
907         {11,"kmsg",    S_IRUGO | S_IWUSR,           &kmsg_fops},
908 #ifdef CONFIG_CRASH_DUMP
909         {12,"oldmem",    S_IRUSR | S_IWUSR | S_IRGRP, &oldmem_fops},
910 #endif
911 };
912
913 static struct class *mem_class;
914
915 static int __init chr_dev_init(void)
916 {
917         int i;
918
919         if (register_chrdev(MEM_MAJOR,"mem",&memory_fops))
920                 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
921
922         mem_class = class_create(THIS_MODULE, "mem");
923         for (i = 0; i < ARRAY_SIZE(devlist); i++) {
924                 class_device_create(mem_class, NULL,
925                                         MKDEV(MEM_MAJOR, devlist[i].minor),
926                                         NULL, devlist[i].name);
927                 devfs_mk_cdev(MKDEV(MEM_MAJOR, devlist[i].minor),
928                                 S_IFCHR | devlist[i].mode, devlist[i].name);
929         }
930         
931         return 0;
932 }
933
934 fs_initcall(chr_dev_init);