drivers/char/mem.c

/* */
This source file includes following definitions.
read_ram
write_ram
read_mem
write_mem
mmap_mem
read_kmem
read_port
write_port
read_null
write_null
read_zero
mmap_zero
null_lseek
memory_lseek
memory_open
chr_dev_init
   1 /*
   2  *  linux/kernel/chr_drv/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/mouse.h>
  15 #include <linux/tpqic02.h>
  16 #include <linux/malloc.h>
  17 #include <linux/mman.h>
  18 
  19 #include <asm/segment.h>
  20 #include <asm/io.h>
  21 
  22 #ifdef CONFIG_SOUND
  23 extern long soundcard_init(long mem_start);
  24 #endif
  25 
  26 static int read_ram(struct inode * inode, struct file * file,char * buf, int count)
     /*  */
  27 {
  28         return -EIO;
  29 }
  30 
  31 static int write_ram(struct inode * inode, struct file * file,char * buf, int count)
     /*  */
  32 {
  33         return -EIO;
  34 }
  35 
  36 static int read_mem(struct inode * inode, struct file * file,char * buf, int count)
     /*  */
  37 {
  38         unsigned long p = file->f_pos;
  39         int read;
  40 
  41         if (count < 0)
  42                 return -EINVAL;
  43         if (p >= high_memory)
  44                 return 0;
  45         if (count > high_memory - p)
  46                 count = high_memory - p;
  47         read = 0;
  48         while (p < PAGE_SIZE && count > 0) {
  49                 put_fs_byte(0,buf);
  50                 buf++;
  51                 p++;
  52                 count--;
  53                 read++;
  54         }
  55         memcpy_tofs(buf,(void *) p,count);
  56         read += count;
  57         file->f_pos += read;
  58         return read;
  59 }
  60 
  61 static int write_mem(struct inode * inode, struct file * file,char * buf, int count)
     /*  */
  62 {
  63         unsigned long p = file->f_pos;
  64         int written;
  65 
  66         if (count < 0)
  67                 return -EINVAL;
  68         if (p >= high_memory)
  69                 return 0;
  70         if (count > high_memory - p)
  71                 count = high_memory - p;
  72         written = 0;
  73         while (p < PAGE_SIZE && count > 0) {
  74                 /* Hmm. Do something? */
  75                 buf++;
  76                 p++;
  77                 count--;
  78                 written++;
  79         }
  80         memcpy_fromfs((void *) p,buf,count);
  81         written += count;
  82         file->f_pos += written;
  83         return count;
  84 }
  85 
  86 static int mmap_mem(struct inode * inode, struct file * file,
     /*  */
  87         unsigned long addr, size_t len, int prot, unsigned long off)
  88 {
  89         struct vm_area_struct * mpnt;
  90 
  91         if (off & 0xfff || off + len < off)
  92                 return -ENXIO;
  93         if (remap_page_range(addr, off, len, prot))
  94                 return -EAGAIN;
  95 /* try to create a dummy vmm-structure so that the rest of the kernel knows we are here */
  96         mpnt = (struct vm_area_struct * ) kmalloc(sizeof(struct vm_area_struct), GFP_KERNEL);
  97         if (!mpnt)
  98                 return 0;
  99 
 100         mpnt->vm_task = current;
 101         mpnt->vm_start = addr;
 102         mpnt->vm_end = addr + len;
 103         mpnt->vm_page_prot = prot;
 104         mpnt->vm_share = NULL;
 105         mpnt->vm_inode = inode;
 106         inode->i_count++;
 107         mpnt->vm_offset = off;
 108         mpnt->vm_ops = NULL;
 109         insert_vm_struct(current, mpnt);
 110         merge_segments(current->mmap, NULL, NULL);
 111         return 0;
 112 }
 113 
 114 static int read_kmem(struct inode *inode, struct file *file, char *buf, int count)
     /*  */
 115 {
 116         int read1, read2;
 117 
 118         read1 = read_mem(inode, file, buf, count);
 119         if (read1 < 0)
 120                 return read1;
 121         read2 = vread(buf + read1, (char *) file->f_pos, count - read1);
 122         if (read2 < 0)
 123                 return read2;
 124         file->f_pos += read2;
 125         return read1 + read2;
 126 }
 127 
 128 static int read_port(struct inode * inode,struct file * file,char * buf, int count)
     /*  */
 129 {
 130         unsigned int i = file->f_pos;
 131         char * tmp = buf;
 132 
 133         while (count-- > 0 && i < 65536) {
 134                 put_fs_byte(inb(i),tmp);
 135                 i++;
 136                 tmp++;
 137         }
 138         file->f_pos = i;
 139         return tmp-buf;
 140 }
 141 
 142 static int write_port(struct inode * inode,struct file * file,char * buf, int count)
     /*  */
 143 {
 144         unsigned int i = file->f_pos;
 145         char * tmp = buf;
 146 
 147         while (count-- > 0 && i < 65536) {
 148                 outb(get_fs_byte(tmp),i);
 149                 i++;
 150                 tmp++;
 151         }
 152         file->f_pos = i;
 153         return tmp-buf;
 154 }
 155 
 156 static int read_null(struct inode * node,struct file * file,char * buf,int count)
     /*  */
 157 {
 158         return 0;
 159 }
 160 
 161 static int write_null(struct inode * inode,struct file * file,char * buf, int count)
     /*  */
 162 {
 163         return count;
 164 }
 165 
 166 static int read_zero(struct inode * node,struct file * file,char * buf,int count)
     /*  */
 167 {
 168         int left;
 169 
 170         for (left = count; left > 0; left--) {
 171                 put_fs_byte(0,buf);
 172                 buf++;
 173         }
 174         return count;
 175 }
 176 
 177 static int mmap_zero(struct inode * inode, struct file * file,
     /*  */
 178         unsigned long addr, size_t len, int prot, unsigned long off)
 179 {
 180         struct vm_area_struct *mpnt;
 181 
 182         if (prot & PAGE_RW)
 183                 return -EINVAL;
 184         if (zeromap_page_range(addr, len, prot))
 185                 return -EAGAIN;
 186         /*
 187          * try to create a dummy vmm-structure so that the
 188          * rest of the kernel knows we are here
 189          */
 190         mpnt = (struct vm_area_struct *)kmalloc(sizeof(*mpnt), GFP_KERNEL);
 191         if (!mpnt)
 192                 return 0;
 193 
 194         mpnt->vm_task = current;
 195         mpnt->vm_start = addr;
 196         mpnt->vm_end = addr + len;
 197         mpnt->vm_page_prot = prot;
 198         mpnt->vm_share = NULL;
 199         mpnt->vm_inode = inode;
 200         inode->i_count++;
 201         mpnt->vm_offset = off;
 202         mpnt->vm_ops = NULL;
 203         insert_vm_struct(current, mpnt);
 204         merge_segments(current->mmap, ignoff_mergep, inode);
 205         return 0;
 206 }
 207 
 208 /*
 209  * Special lseek() function for /dev/null and /dev/zero.  Most notably, you can fopen()
 210  * both devices with "a" now.  This was previously impossible.  SRB.
 211  */
 212 
 213 static int null_lseek(struct inode * inode, struct file * file, off_t offset, int orig)
     /*  */
 214 {
 215         return file->f_pos=0;
 216 }
 217 /*
 218  * The memory devices use the full 32 bits of the offset, and so we cannot
 219  * check against negative addresses: they are ok. The return value is weird,
 220  * though, in that case (0).
 221  *
 222  * also note that seeking relative to the "end of file" isn't supported:
 223  * it has no meaning, so it returns -EINVAL.
 224  */
 225 static int memory_lseek(struct inode * inode, struct file * file, off_t offset, int orig)
     /*  */
 226 {
 227         switch (orig) {
 228                 case 0:
 229                         file->f_pos = offset;
 230                         return file->f_pos;
 231                 case 1:
 232                         file->f_pos += offset;
 233                         return file->f_pos;
 234                 default:
 235                         return -EINVAL;
 236         }
 237         if (file->f_pos < 0)
 238                 return 0;
 239         return file->f_pos;
 240 }
 241 
 242 #define write_kmem      write_mem
 243 #define mmap_kmem       mmap_mem
 244 #define zero_lseek      null_lseek
 245 #define write_zero      write_null
 246 
 247 static struct file_operations ram_fops = {
 248         memory_lseek,
 249         read_ram,
 250         write_ram,
 251         NULL,           /* ram_readdir */
 252         NULL,           /* ram_select */
 253         NULL,           /* ram_ioctl */
 254         NULL,           /* ram_mmap */
 255         NULL,           /* no special open code */
 256         NULL,           /* no special release code */
 257         NULL            /* fsync */
 258 };
 259 
 260 static struct file_operations mem_fops = {
 261         memory_lseek,
 262         read_mem,
 263         write_mem,
 264         NULL,           /* mem_readdir */
 265         NULL,           /* mem_select */
 266         NULL,           /* mem_ioctl */
 267         mmap_mem,
 268         NULL,           /* no special open code */
 269         NULL,           /* no special release code */
 270         NULL            /* fsync */
 271 };
 272 
 273 static struct file_operations kmem_fops = {
 274         memory_lseek,
 275         read_kmem,
 276         write_kmem,
 277         NULL,           /* kmem_readdir */
 278         NULL,           /* kmem_select */
 279         NULL,           /* kmem_ioctl */
 280         mmap_kmem,
 281         NULL,           /* no special open code */
 282         NULL,           /* no special release code */
 283         NULL            /* fsync */
 284 };
 285 
 286 static struct file_operations null_fops = {
 287         null_lseek,
 288         read_null,
 289         write_null,
 290         NULL,           /* null_readdir */
 291         NULL,           /* null_select */
 292         NULL,           /* null_ioctl */
 293         NULL,           /* null_mmap */
 294         NULL,           /* no special open code */
 295         NULL,           /* no special release code */
 296         NULL            /* fsync */
 297 };
 298 
 299 static struct file_operations port_fops = {
 300         memory_lseek,
 301         read_port,
 302         write_port,
 303         NULL,           /* port_readdir */
 304         NULL,           /* port_select */
 305         NULL,           /* port_ioctl */
 306         NULL,           /* port_mmap */
 307         NULL,           /* no special open code */
 308         NULL,           /* no special release code */
 309         NULL            /* fsync */
 310 };
 311 
 312 static struct file_operations zero_fops = {
 313         zero_lseek,
 314         read_zero,
 315         write_zero,
 316         NULL,           /* zero_readdir */
 317         NULL,           /* zero_select */
 318         NULL,           /* zero_ioctl */
 319         mmap_zero,
 320         NULL,           /* no special open code */
 321         NULL            /* no special release code */
 322 };
 323 
 324 static int memory_open(struct inode * inode, struct file * filp)
     /*  */
 325 {
 326         switch (MINOR(inode->i_rdev)) {
 327                 case 0:
 328                         filp->f_op = &ram_fops;
 329                         break;
 330                 case 1:
 331                         filp->f_op = &mem_fops;
 332                         break;
 333                 case 2:
 334                         filp->f_op = &kmem_fops;
 335                         break;
 336                 case 3:
 337                         filp->f_op = &null_fops;
 338                         break;
 339                 case 4:
 340                         filp->f_op = &port_fops;
 341                         break;
 342                 case 5:
 343                         filp->f_op = &zero_fops;
 344                         break;
 345                 default:
 346                         return -ENODEV;
 347         }
 348         if (filp->f_op && filp->f_op->open)
 349                 return filp->f_op->open(inode,filp);
 350         return 0;
 351 }
 352 
 353 static struct file_operations memory_fops = {
 354         NULL,           /* lseek */
 355         NULL,           /* read */
 356         NULL,           /* write */
 357         NULL,           /* readdir */
 358         NULL,           /* select */
 359         NULL,           /* ioctl */
 360         NULL,           /* mmap */
 361         memory_open,    /* just a selector for the real open */
 362         NULL,           /* release */
 363         NULL            /* fsync */
 364 };
 365 
 366 long chr_dev_init(long mem_start, long mem_end)
     /*  */
 367 {
 368         if (register_chrdev(MEM_MAJOR,"mem",&memory_fops))
 369                 printk("unable to get major %d for memory devs\n", MEM_MAJOR);
 370         mem_start = tty_init(mem_start);
 371 #ifdef CONFIG_PRINTER
 372         mem_start = lp_init(mem_start);
 373 #endif
 374 #if defined (CONFIG_BUSMOUSE) || defined (CONFIG_82C710_MOUSE) || \
 375     defined (CONFIG_PSMOUSE) || defined (CONFIG_MS_BUSMOUSE) || \
 376     defined (CONFIG_ATIXL_BUSMOUSE)
 377         mem_start = mouse_init(mem_start);
 378 #endif
 379 #ifdef CONFIG_SOUND
 380         mem_start = soundcard_init(mem_start);
 381 #endif
 382 #if CONFIG_TAPE_QIC02
 383         mem_start = tape_qic02_init(mem_start);
 384 #endif
 385         return mem_start;
 386 }
/* */
root/drivers/char/mem.c

DEFINITIONS
