include/asm-m68knommu/dma.h

   1 #ifndef _M68K_DMA_H
   2 #define _M68K_DMA_H 1
   3
   4 //#define       DMA_DEBUG       1
   5
   6
   7 #ifdef CONFIG_COLDFIRE
   8 /*
   9  * ColdFire DMA Model:
  10  *   ColdFire DMA supports two forms of DMA: Single and Dual address. Single
  11  * address mode emits a source address, and expects that the device will either
  12  * pick up the data (DMA READ) or source data (DMA WRITE). This implies that
  13  * the device will place data on the correct byte(s) of the data bus, as the
  14  * memory transactions are always 32 bits. This implies that only 32 bit
  15  * devices will find single mode transfers useful. Dual address DMA mode
  16  * performs two cycles: source read and destination write. ColdFire will
  17  * align the data so that the device will always get the correct bytes, thus
  18  * is useful for 8 and 16 bit devices. This is the mode that is supported
  19  * below.
  20  *
  21  * AUG/22/2000 : added support for 32-bit Dual-Address-Mode (K) 2000
  22  *               Oliver Kamphenkel (O.Kamphenkel@tu-bs.de)
  23  *
  24  * AUG/25/2000 : addad support for 8, 16 and 32-bit Single-Address-Mode (K)2000
  25  *               Oliver Kamphenkel (O.Kamphenkel@tu-bs.de)
  26  *
  27  * APR/18/2002 : added proper support for MCF5272 DMA controller.
  28  *               Arthur Shipkowski (art@videon-central.com)
  29  */
  30
  31 #include <asm/coldfire.h>
  32 #include <asm/mcfsim.h>
  33 #include <asm/mcfdma.h>
  34
  35 /*
  36  * Set number of channels of DMA on ColdFire for different implementations.
  37  */
  38 #if defined(CONFIG_M5249) || defined(CONFIG_M5307) || defined(CONFIG_M5407) || \
  39         defined(CONFIG_M523x) || defined(CONFIG_M527x) || defined(CONFIG_M528x)
  40 #define MAX_M68K_DMA_CHANNELS 4
  41 #elif defined(CONFIG_M5272)
  42 #define MAX_M68K_DMA_CHANNELS 1
  43 #elif defined(CONFIG_M532x)
  44 #define MAX_M68K_DMA_CHANNELS 0
  45 #else
  46 #define MAX_M68K_DMA_CHANNELS 2
  47 #endif
  48
  49 extern unsigned int dma_base_addr[MAX_M68K_DMA_CHANNELS];
  50 extern unsigned int dma_device_address[MAX_M68K_DMA_CHANNELS];
  51
  52 #if !defined(CONFIG_M5272)
  53 #define DMA_MODE_WRITE_BIT  0x01  /* Memory/IO to IO/Memory select */
  54 #define DMA_MODE_WORD_BIT   0x02  /* 8 or 16 bit transfers */
  55 #define DMA_MODE_LONG_BIT   0x04  /* or 32 bit transfers */
  56 #define DMA_MODE_SINGLE_BIT 0x08  /* single-address-mode */
  57
  58 /* I/O to memory, 8 bits, mode */
  59 #define DMA_MODE_READ               0
  60 /* memory to I/O, 8 bits, mode */
  61 #define DMA_MODE_WRITE              1
  62 /* I/O to memory, 16 bits, mode */
  63 #define DMA_MODE_READ_WORD          2
  64 /* memory to I/O, 16 bits, mode */
  65 #define DMA_MODE_WRITE_WORD         3
  66 /* I/O to memory, 32 bits, mode */
  67 #define DMA_MODE_READ_LONG          4
  68 /* memory to I/O, 32 bits, mode */
  69 #define DMA_MODE_WRITE_LONG         5
  70 /* I/O to memory, 8 bits, single-address-mode */
  71 #define DMA_MODE_READ_SINGLE        8
  72 /* memory to I/O, 8 bits, single-address-mode */
  73 #define DMA_MODE_WRITE_SINGLE       9
  74 /* I/O to memory, 16 bits, single-address-mode */
  75 #define DMA_MODE_READ_WORD_SINGLE  10
  76 /* memory to I/O, 16 bits, single-address-mode */
  77 #define DMA_MODE_WRITE_WORD_SINGLE 11
  78 /* I/O to memory, 32 bits, single-address-mode */
  79 #define DMA_MODE_READ_LONG_SINGLE  12
  80 /* memory to I/O, 32 bits, single-address-mode */
  81 #define DMA_MODE_WRITE_LONG_SINGLE 13
  82
  83 #else /* CONFIG_M5272 is defined */
  84
  85 /* Source static-address mode */
  86 #define DMA_MODE_SRC_SA_BIT 0x01
  87 /* Two bits to select between all four modes */
  88 #define DMA_MODE_SSIZE_MASK 0x06
  89 /* Offset to shift bits in */
  90 #define DMA_MODE_SSIZE_OFF  0x01
  91 /* Destination static-address mode */
  92 #define DMA_MODE_DES_SA_BIT 0x10
  93 /* Two bits to select between all four modes */
  94 #define DMA_MODE_DSIZE_MASK 0x60
  95 /* Offset to shift bits in */
  96 #define DMA_MODE_DSIZE_OFF  0x05
  97 /* Size modifiers */
  98 #define DMA_MODE_SIZE_LONG  0x00
  99 #define DMA_MODE_SIZE_BYTE  0x01
 100 #define DMA_MODE_SIZE_WORD  0x02
 101 #define DMA_MODE_SIZE_LINE  0x03
 102
 103 /*
 104  * Aliases to help speed quick ports; these may be suboptimal, however. They
 105  * do not include the SINGLE mode modifiers since the MCF5272 does not have a
 106  * mode where the device is in control of its addressing.
 107  */
 108
 109 /* I/O to memory, 8 bits, mode */
 110 #define DMA_MODE_READ                 ((DMA_MODE_SIZE_BYTE << DMA_MODE_DSIZE_OFF) | (DMA_MODE_SIZE_BYTE << DMA_MODE_SSIZE_OFF) | DMA_SRC_SA_BIT)
 111 /* memory to I/O, 8 bits, mode */
 112 #define DMA_MODE_WRITE              ((DMA_MODE_SIZE_BYTE << DMA_MODE_DSIZE_OFF) | (DMA_MODE_SIZE_BYTE << DMA_MODE_SSIZE_OFF) | DMA_DES_SA_BIT)
 113 /* I/O to memory, 16 bits, mode */
 114 #define DMA_MODE_READ_WORD              ((DMA_MODE_SIZE_WORD << DMA_MODE_DSIZE_OFF) | (DMA_MODE_SIZE_WORD << DMA_MODE_SSIZE_OFF) | DMA_SRC_SA_BIT)
 115 /* memory to I/O, 16 bits, mode */
 116 #define DMA_MODE_WRITE_WORD         ((DMA_MODE_SIZE_WORD << DMA_MODE_DSIZE_OFF) | (DMA_MODE_SIZE_WORD << DMA_MODE_SSIZE_OFF) | DMA_DES_SA_BIT)
 117 /* I/O to memory, 32 bits, mode */
 118 #define DMA_MODE_READ_LONG              ((DMA_MODE_SIZE_LONG << DMA_MODE_DSIZE_OFF) | (DMA_MODE_SIZE_LONG << DMA_MODE_SSIZE_OFF) | DMA_SRC_SA_BIT)
 119 /* memory to I/O, 32 bits, mode */
 120 #define DMA_MODE_WRITE_LONG         ((DMA_MODE_SIZE_LONG << DMA_MODE_DSIZE_OFF) | (DMA_MODE_SIZE_LONG << DMA_MODE_SSIZE_OFF) | DMA_DES_SA_BIT)
 121
 122 #endif /* !defined(CONFIG_M5272) */
 123
 124 #if !defined(CONFIG_M5272)
 125 /* enable/disable a specific DMA channel */
 126 static __inline__ void enable_dma(unsigned int dmanr)
 127 {
 128   volatile unsigned short *dmawp;
 129
 130 #ifdef DMA_DEBUG
 131   printk("enable_dma(dmanr=%d)\n", dmanr);
 132 #endif
 133
 134   dmawp = (unsigned short *) dma_base_addr[dmanr];
 135   dmawp[MCFDMA_DCR] |= MCFDMA_DCR_EEXT;
 136 }
 137
 138 static __inline__ void disable_dma(unsigned int dmanr)
 139 {
 140   volatile unsigned short *dmawp;
 141   volatile unsigned char  *dmapb;
 142
 143 #ifdef DMA_DEBUG
 144   printk("disable_dma(dmanr=%d)\n", dmanr);
 145 #endif
 146
 147   dmawp = (unsigned short *) dma_base_addr[dmanr];
 148   dmapb = (unsigned char *) dma_base_addr[dmanr];
 149
 150   /* Turn off external requests, and stop any DMA in progress */
 151   dmawp[MCFDMA_DCR] &= ~MCFDMA_DCR_EEXT;
 152   dmapb[MCFDMA_DSR] = MCFDMA_DSR_DONE;
 153 }
 154
 155 /*
 156  * Clear the 'DMA Pointer Flip Flop'.
 157  * Write 0 for LSB/MSB, 1 for MSB/LSB access.
 158  * Use this once to initialize the FF to a known state.
 159  * After that, keep track of it. :-)
 160  * --- In order to do that, the DMA routines below should ---
 161  * --- only be used while interrupts are disabled! ---
 162  *
 163  * This is a NOP for ColdFire. Provide a stub for compatibility.
 164  */
 165 static __inline__ void clear_dma_ff(unsigned int dmanr)
 166 {
 167 }
 168
 169 /* set mode (above) for a specific DMA channel */
 170 static __inline__ void set_dma_mode(unsigned int dmanr, char mode)
 171 {
 172
 173   volatile unsigned char  *dmabp;
 174   volatile unsigned short *dmawp;
 175
 176 #ifdef DMA_DEBUG
 177   printk("set_dma_mode(dmanr=%d,mode=%d)\n", dmanr, mode);
 178 #endif
 179
 180   dmabp = (unsigned char *) dma_base_addr[dmanr];
 181   dmawp = (unsigned short *) dma_base_addr[dmanr];
 182
 183   // Clear config errors
 184   dmabp[MCFDMA_DSR] = MCFDMA_DSR_DONE;
 185
 186   // Set command register
 187   dmawp[MCFDMA_DCR] =
 188     MCFDMA_DCR_INT |         // Enable completion irq
 189     MCFDMA_DCR_CS |          // Force one xfer per request
 190     MCFDMA_DCR_AA |          // Enable auto alignment
 191     // single-address-mode
 192     ((mode & DMA_MODE_SINGLE_BIT) ? MCFDMA_DCR_SAA : 0) |
 193     // sets s_rw (-> r/w) high if Memory to I/0
 194     ((mode & DMA_MODE_WRITE_BIT) ? MCFDMA_DCR_S_RW : 0) |
 195     // Memory to I/O or I/O to Memory
 196     ((mode & DMA_MODE_WRITE_BIT) ? MCFDMA_DCR_SINC : MCFDMA_DCR_DINC) |
 197     // 32 bit, 16 bit or 8 bit transfers
 198     ((mode & DMA_MODE_WORD_BIT)  ? MCFDMA_DCR_SSIZE_WORD :
 199      ((mode & DMA_MODE_LONG_BIT) ? MCFDMA_DCR_SSIZE_LONG :
 200                                    MCFDMA_DCR_SSIZE_BYTE)) |
 201     ((mode & DMA_MODE_WORD_BIT)  ? MCFDMA_DCR_DSIZE_WORD :
 202      ((mode & DMA_MODE_LONG_BIT) ? MCFDMA_DCR_DSIZE_LONG :
 203                                    MCFDMA_DCR_DSIZE_BYTE));
 204
 205 #ifdef DEBUG_DMA
 206   printk("%s(%d): dmanr=%d DSR[%x]=%x DCR[%x]=%x\n", __FILE__, __LINE__,
 207          dmanr, (int) &dmabp[MCFDMA_DSR], dmabp[MCFDMA_DSR],
 208          (int) &dmawp[MCFDMA_DCR], dmawp[MCFDMA_DCR]);
 209 #endif
 210 }
 211
 212 /* Set transfer address for specific DMA channel */
 213 static __inline__ void set_dma_addr(unsigned int dmanr, unsigned int a)
 214 {
 215   volatile unsigned short *dmawp;
 216   volatile unsigned int   *dmalp;
 217
 218 #ifdef DMA_DEBUG
 219   printk("set_dma_addr(dmanr=%d,a=%x)\n", dmanr, a);
 220 #endif
 221
 222   dmawp = (unsigned short *) dma_base_addr[dmanr];
 223   dmalp = (unsigned int *) dma_base_addr[dmanr];
 224
 225   // Determine which address registers are used for memory/device accesses
 226   if (dmawp[MCFDMA_DCR] & MCFDMA_DCR_SINC) {
 227     // Source incrementing, must be memory
 228     dmalp[MCFDMA_SAR] = a;
 229     // Set dest address, must be device
 230     dmalp[MCFDMA_DAR] = dma_device_address[dmanr];
 231   } else {
 232     // Destination incrementing, must be memory
 233     dmalp[MCFDMA_DAR] = a;
 234     // Set source address, must be device
 235     dmalp[MCFDMA_SAR] = dma_device_address[dmanr];
 236   }
 237
 238 #ifdef DEBUG_DMA
 239   printk("%s(%d): dmanr=%d DCR[%x]=%x SAR[%x]=%08x DAR[%x]=%08x\n",
 240         __FILE__, __LINE__, dmanr, (int) &dmawp[MCFDMA_DCR], dmawp[MCFDMA_DCR],
 241         (int) &dmalp[MCFDMA_SAR], dmalp[MCFDMA_SAR],
 242         (int) &dmalp[MCFDMA_DAR], dmalp[MCFDMA_DAR]);
 243 #endif
 244 }
 245
 246 /*
 247  * Specific for Coldfire - sets device address.
 248  * Should be called after the mode set call, and before set DMA address.
 249  */
 250 static __inline__ void set_dma_device_addr(unsigned int dmanr, unsigned int a)
 251 {
 252 #ifdef DMA_DEBUG
 253   printk("set_dma_device_addr(dmanr=%d,a=%x)\n", dmanr, a);
 254 #endif
 255
 256   dma_device_address[dmanr] = a;
 257 }
 258
 259 /*
 260  * NOTE 2: "count" represents _bytes_.
 261  */
 262 static __inline__ void set_dma_count(unsigned int dmanr, unsigned int count)
 263 {
 264   volatile unsigned short *dmawp;
 265
 266 #ifdef DMA_DEBUG
 267   printk("set_dma_count(dmanr=%d,count=%d)\n", dmanr, count);
 268 #endif
 269
 270   dmawp = (unsigned short *) dma_base_addr[dmanr];
 271   dmawp[MCFDMA_BCR] = (unsigned short)count;
 272 }
 273
 274 /*
 275  * Get DMA residue count. After a DMA transfer, this
 276  * should return zero. Reading this while a DMA transfer is
 277  * still in progress will return unpredictable results.
 278  * Otherwise, it returns the number of _bytes_ left to transfer.
 279  */
 280 static __inline__ int get_dma_residue(unsigned int dmanr)
 281 {
 282   volatile unsigned short *dmawp;
 283   unsigned short count;
 284
 285 #ifdef DMA_DEBUG
 286   printk("get_dma_residue(dmanr=%d)\n", dmanr);
 287 #endif
 288
 289   dmawp = (unsigned short *) dma_base_addr[dmanr];
 290   count = dmawp[MCFDMA_BCR];
 291   return((int) count);
 292 }
 293 #else /* CONFIG_M5272 is defined */
 294
 295 /*
 296  * The MCF5272 DMA controller is very different than the controller defined above
 297  * in terms of register mapping.  For instance, with the exception of the 16-bit
 298  * interrupt register (IRQ#85, for reference), all of the registers are 32-bit.
 299  *
 300  * The big difference, however, is the lack of device-requested DMA.  All modes
 301  * are dual address transfer, and there is no 'device' setup or direction bit.
 302  * You can DMA between a device and memory, between memory and memory, or even between
 303  * two devices directly, with any combination of incrementing and non-incrementing
 304  * addresses you choose.  This puts a crimp in distinguishing between the 'device
 305  * address' set up by set_dma_device_addr.
 306  *
 307  * Therefore, there are two options.  One is to use set_dma_addr and set_dma_device_addr,
 308  * which will act exactly as above in -- it will look to see if the source is set to
 309  * autoincrement, and if so it will make the source use the set_dma_addr value and the
 310  * destination the set_dma_device_addr value.  Otherwise the source will be set to the
 311  * set_dma_device_addr value and the destination will get the set_dma_addr value.
 312  *
 313  * The other is to use the provided set_dma_src_addr and set_dma_dest_addr functions
 314  * and make it explicit.  Depending on what you're doing, one of these two should work
 315  * for you, but don't mix them in the same transfer setup.
 316  */
 317
 318 /* enable/disable a specific DMA channel */
 319 static __inline__ void enable_dma(unsigned int dmanr)
 320 {
 321   volatile unsigned int  *dmalp;
 322
 323 #ifdef DMA_DEBUG
 324   printk("enable_dma(dmanr=%d)\n", dmanr);
 325 #endif
 326
 327   dmalp = (unsigned int *) dma_base_addr[dmanr];
 328   dmalp[MCFDMA_DMR] |= MCFDMA_DMR_EN;
 329 }
 330
 331 static __inline__ void disable_dma(unsigned int dmanr)
 332 {
 333   volatile unsigned int   *dmalp;
 334
 335 #ifdef DMA_DEBUG
 336   printk("disable_dma(dmanr=%d)\n", dmanr);
 337 #endif
 338
 339   dmalp = (unsigned int *) dma_base_addr[dmanr];
 340
 341   /* Turn off external requests, and stop any DMA in progress */
 342   dmalp[MCFDMA_DMR] &= ~MCFDMA_DMR_EN;
 343   dmalp[MCFDMA_DMR] |= MCFDMA_DMR_RESET;
 344 }
 345
 346 /*
 347  * Clear the 'DMA Pointer Flip Flop'.
 348  * Write 0 for LSB/MSB, 1 for MSB/LSB access.
 349  * Use this once to initialize the FF to a known state.
 350  * After that, keep track of it. :-)
 351  * --- In order to do that, the DMA routines below should ---
 352  * --- only be used while interrupts are disabled! ---
 353  *
 354  * This is a NOP for ColdFire. Provide a stub for compatibility.
 355  */
 356 static __inline__ void clear_dma_ff(unsigned int dmanr)
 357 {
 358 }
 359
 360 /* set mode (above) for a specific DMA channel */
 361 static __inline__ void set_dma_mode(unsigned int dmanr, char mode)
 362 {
 363
 364   volatile unsigned int   *dmalp;
 365   volatile unsigned short *dmawp;
 366
 367 #ifdef DMA_DEBUG
 368   printk("set_dma_mode(dmanr=%d,mode=%d)\n", dmanr, mode);
 369 #endif
 370   dmalp = (unsigned int *) dma_base_addr[dmanr];
 371   dmawp = (unsigned short *) dma_base_addr[dmanr];
 372
 373   // Clear config errors
 374   dmalp[MCFDMA_DMR] |= MCFDMA_DMR_RESET;
 375
 376   // Set command register
 377   dmalp[MCFDMA_DMR] =
 378     MCFDMA_DMR_RQM_DUAL |         // Mandatory Request Mode setting
 379     MCFDMA_DMR_DSTT_SD  |         // Set up addressing types; set to supervisor-data.
 380     MCFDMA_DMR_SRCT_SD  |         // Set up addressing types; set to supervisor-data.
 381     // source static-address-mode
 382     ((mode & DMA_MODE_SRC_SA_BIT) ? MCFDMA_DMR_SRCM_SA : MCFDMA_DMR_SRCM_IA) |
 383     // dest static-address-mode
 384     ((mode & DMA_MODE_DES_SA_BIT) ? MCFDMA_DMR_DSTM_SA : MCFDMA_DMR_DSTM_IA) |
 385     // burst, 32 bit, 16 bit or 8 bit transfers are separately configurable on the MCF5272
 386     (((mode & DMA_MODE_SSIZE_MASK) >> DMA_MODE_SSIZE_OFF) << MCFDMA_DMR_DSTS_OFF) |
 387     (((mode & DMA_MODE_SSIZE_MASK) >> DMA_MODE_SSIZE_OFF) << MCFDMA_DMR_SRCS_OFF);
 388
 389   dmawp[MCFDMA_DIR] |= MCFDMA_DIR_ASCEN;   /* Enable completion interrupts */
 390
 391 #ifdef DEBUG_DMA
 392   printk("%s(%d): dmanr=%d DMR[%x]=%x DIR[%x]=%x\n", __FILE__, __LINE__,
 393          dmanr, (int) &dmalp[MCFDMA_DMR], dmabp[MCFDMA_DMR],
 394          (int) &dmawp[MCFDMA_DIR], dmawp[MCFDMA_DIR]);
 395 #endif
 396 }
 397
 398 /* Set transfer address for specific DMA channel */
 399 static __inline__ void set_dma_addr(unsigned int dmanr, unsigned int a)
 400 {
 401   volatile unsigned int   *dmalp;
 402
 403 #ifdef DMA_DEBUG
 404   printk("set_dma_addr(dmanr=%d,a=%x)\n", dmanr, a);
 405 #endif
 406
 407   dmalp = (unsigned int *) dma_base_addr[dmanr];
 408
 409   // Determine which address registers are used for memory/device accesses
 410   if (dmalp[MCFDMA_DMR] & MCFDMA_DMR_SRCM) {
 411     // Source incrementing, must be memory
 412     dmalp[MCFDMA_DSAR] = a;
 413     // Set dest address, must be device
 414     dmalp[MCFDMA_DDAR] = dma_device_address[dmanr];
 415   } else {
 416     // Destination incrementing, must be memory
 417     dmalp[MCFDMA_DDAR] = a;
 418     // Set source address, must be device
 419     dmalp[MCFDMA_DSAR] = dma_device_address[dmanr];
 420   }
 421
 422 #ifdef DEBUG_DMA
 423   printk("%s(%d): dmanr=%d DMR[%x]=%x SAR[%x]=%08x DAR[%x]=%08x\n",
 424         __FILE__, __LINE__, dmanr, (int) &dmawp[MCFDMA_DMR], dmawp[MCFDMA_DMR],
 425         (int) &dmalp[MCFDMA_DSAR], dmalp[MCFDMA_DSAR],
 426         (int) &dmalp[MCFDMA_DDAR], dmalp[MCFDMA_DDAR]);
 427 #endif
 428 }
 429
 430 /*
 431  * Specific for Coldfire - sets device address.
 432  * Should be called after the mode set call, and before set DMA address.
 433  */
 434 static __inline__ void set_dma_device_addr(unsigned int dmanr, unsigned int a)
 435 {
 436 #ifdef DMA_DEBUG
 437   printk("set_dma_device_addr(dmanr=%d,a=%x)\n", dmanr, a);
 438 #endif
 439
 440   dma_device_address[dmanr] = a;
 441 }
 442
 443 /*
 444  * NOTE 2: "count" represents _bytes_.
 445  *
 446  * NOTE 3: While a 32-bit register, "count" is only a maximum 24-bit value.
 447  */
 448 static __inline__ void set_dma_count(unsigned int dmanr, unsigned int count)
 449 {
 450   volatile unsigned int *dmalp;
 451
 452 #ifdef DMA_DEBUG
 453   printk("set_dma_count(dmanr=%d,count=%d)\n", dmanr, count);
 454 #endif
 455
 456   dmalp = (unsigned int *) dma_base_addr[dmanr];
 457   dmalp[MCFDMA_DBCR] = count;
 458 }
 459
 460 /*
 461  * Get DMA residue count. After a DMA transfer, this
 462  * should return zero. Reading this while a DMA transfer is
 463  * still in progress will return unpredictable results.
 464  * Otherwise, it returns the number of _bytes_ left to transfer.
 465  */
 466 static __inline__ int get_dma_residue(unsigned int dmanr)
 467 {
 468   volatile unsigned int *dmalp;
 469   unsigned int count;
 470
 471 #ifdef DMA_DEBUG
 472   printk("get_dma_residue(dmanr=%d)\n", dmanr);
 473 #endif
 474
 475   dmalp = (unsigned int *) dma_base_addr[dmanr];
 476   count = dmalp[MCFDMA_DBCR];
 477   return(count);
 478 }
 479
 480 #endif /* !defined(CONFIG_M5272) */
 481 #endif /* CONFIG_COLDFIRE */
 482
 483 #define MAX_DMA_CHANNELS 8
 484
 485 /* Don't define MAX_DMA_ADDRESS; it's useless on the m68k/coldfire and any
 486    occurrence should be flagged as an error.  */
 487 /* under 2.4 it is actually needed by the new bootmem allocator */
 488 #define MAX_DMA_ADDRESS PAGE_OFFSET
 489
 490 /* These are in kernel/dma.c: */
 491 extern int request_dma(unsigned int dmanr, const char *device_id);      /* reserve a DMA channel */
 492 extern void free_dma(unsigned int dmanr);       /* release it again */
 493
 494 #endif /* _M68K_DMA_H */