include/asm-x86/dma.h

   1 /*
   2  * linux/include/asm/dma.h: Defines for using and allocating dma channels.
   3  * Written by Hennus Bergman, 1992.
   4  * High DMA channel support & info by Hannu Savolainen
   5  * and John Boyd, Nov. 1992.
   6  */
   7
   8 #ifndef ASM_X86__DMA_H
   9 #define ASM_X86__DMA_H
  10
  11 #include <linux/spinlock.h>     /* And spinlocks */
  12 #include <asm/io.h>             /* need byte IO */
  13 #include <linux/delay.h>
  14
  15 #ifdef HAVE_REALLY_SLOW_DMA_CONTROLLER
  16 #define dma_outb        outb_p
  17 #else
  18 #define dma_outb        outb
  19 #endif
  20
  21 #define dma_inb         inb
  22
  23 /*
  24  * NOTES about DMA transfers:
  25  *
  26  *  controller 1: channels 0-3, byte operations, ports 00-1F
  27  *  controller 2: channels 4-7, word operations, ports C0-DF
  28  *
  29  *  - ALL registers are 8 bits only, regardless of transfer size
  30  *  - channel 4 is not used - cascades 1 into 2.
  31  *  - channels 0-3 are byte - addresses/counts are for physical bytes
  32  *  - channels 5-7 are word - addresses/counts are for physical words
  33  *  - transfers must not cross physical 64K (0-3) or 128K (5-7) boundaries
  34  *  - transfer count loaded to registers is 1 less than actual count
  35  *  - controller 2 offsets are all even (2x offsets for controller 1)
  36  *  - page registers for 5-7 don't use data bit 0, represent 128K pages
  37  *  - page registers for 0-3 use bit 0, represent 64K pages
  38  *
  39  * DMA transfers are limited to the lower 16MB of _physical_ memory.
  40  * Note that addresses loaded into registers must be _physical_ addresses,
  41  * not logical addresses (which may differ if paging is active).
  42  *
  43  *  Address mapping for channels 0-3:
  44  *
  45  *   A23 ... A16 A15 ... A8  A7 ... A0    (Physical addresses)
  46  *    |  ...  |   |  ... |   |  ... |
  47  *    |  ...  |   |  ... |   |  ... |
  48  *    |  ...  |   |  ... |   |  ... |
  49  *   P7  ...  P0  A7 ... A0  A7 ... A0
  50  * |    Page    | Addr MSB | Addr LSB |   (DMA registers)
  51  *
  52  *  Address mapping for channels 5-7:
  53  *
  54  *   A23 ... A17 A16 A15 ... A9 A8 A7 ... A1 A0    (Physical addresses)
  55  *    |  ...  |   \   \   ... \  \  \  ... \  \
  56  *    |  ...  |    \   \   ... \  \  \  ... \  (not used)
  57  *    |  ...  |     \   \   ... \  \  \  ... \
  58  *   P7  ...  P1 (0) A7 A6  ... A0 A7 A6 ... A0
  59  * |      Page      |  Addr MSB   |  Addr LSB  |   (DMA registers)
  60  *
  61  * Again, channels 5-7 transfer _physical_ words (16 bits), so addresses
  62  * and counts _must_ be word-aligned (the lowest address bit is _ignored_ at
  63  * the hardware level, so odd-byte transfers aren't possible).
  64  *
  65  * Transfer count (_not # bytes_) is limited to 64K, represented as actual
  66  * count - 1 : 64K => 0xFFFF, 1 => 0x0000.  Thus, count is always 1 or more,
  67  * and up to 128K bytes may be transferred on channels 5-7 in one operation.
  68  *
  69  */
  70
  71 #define MAX_DMA_CHANNELS        8
  72
  73 #ifdef CONFIG_X86_32
  74
  75 /* The maximum address that we can perform a DMA transfer to on this platform */
  76 #define MAX_DMA_ADDRESS      (PAGE_OFFSET + 0x1000000)
  77
  78 #else
  79
  80 /* 16MB ISA DMA zone */
  81 #define MAX_DMA_PFN   ((16 * 1024 * 1024) >> PAGE_SHIFT)
  82
  83 /* 4GB broken PCI/AGP hardware bus master zone */
  84 #define MAX_DMA32_PFN ((4UL * 1024 * 1024 * 1024) >> PAGE_SHIFT)
  85
  86 /* Compat define for old dma zone */
  87 #define MAX_DMA_ADDRESS ((unsigned long)__va(MAX_DMA_PFN << PAGE_SHIFT))
  88
  89 #endif
  90
  91 /* 8237 DMA controllers */
  92 #define IO_DMA1_BASE    0x00    /* 8 bit slave DMA, channels 0..3 */
  93 #define IO_DMA2_BASE    0xC0    /* 16 bit master DMA, ch 4(=slave input)..7 */
  94
  95 /* DMA controller registers */
  96 #define DMA1_CMD_REG            0x08    /* command register (w) */
  97 #define DMA1_STAT_REG           0x08    /* status register (r) */
  98 #define DMA1_REQ_REG            0x09    /* request register (w) */
  99 #define DMA1_MASK_REG           0x0A    /* single-channel mask (w) */
 100 #define DMA1_MODE_REG           0x0B    /* mode register (w) */
 101 #define DMA1_CLEAR_FF_REG       0x0C    /* clear pointer flip-flop (w) */
 102 #define DMA1_TEMP_REG           0x0D    /* Temporary Register (r) */
 103 #define DMA1_RESET_REG          0x0D    /* Master Clear (w) */
 104 #define DMA1_CLR_MASK_REG       0x0E    /* Clear Mask */
 105 #define DMA1_MASK_ALL_REG       0x0F    /* all-channels mask (w) */
 106
 107 #define DMA2_CMD_REG            0xD0    /* command register (w) */
 108 #define DMA2_STAT_REG           0xD0    /* status register (r) */
 109 #define DMA2_REQ_REG            0xD2    /* request register (w) */
 110 #define DMA2_MASK_REG           0xD4    /* single-channel mask (w) */
 111 #define DMA2_MODE_REG           0xD6    /* mode register (w) */
 112 #define DMA2_CLEAR_FF_REG       0xD8    /* clear pointer flip-flop (w) */
 113 #define DMA2_TEMP_REG           0xDA    /* Temporary Register (r) */
 114 #define DMA2_RESET_REG          0xDA    /* Master Clear (w) */
 115 #define DMA2_CLR_MASK_REG       0xDC    /* Clear Mask */
 116 #define DMA2_MASK_ALL_REG       0xDE    /* all-channels mask (w) */
 117
 118 #define DMA_ADDR_0              0x00    /* DMA address registers */
 119 #define DMA_ADDR_1              0x02
 120 #define DMA_ADDR_2              0x04
 121 #define DMA_ADDR_3              0x06
 122 #define DMA_ADDR_4              0xC0
 123 #define DMA_ADDR_5              0xC4
 124 #define DMA_ADDR_6              0xC8
 125 #define DMA_ADDR_7              0xCC
 126
 127 #define DMA_CNT_0               0x01    /* DMA count registers */
 128 #define DMA_CNT_1               0x03
 129 #define DMA_CNT_2               0x05
 130 #define DMA_CNT_3               0x07
 131 #define DMA_CNT_4               0xC2
 132 #define DMA_CNT_5               0xC6
 133 #define DMA_CNT_6               0xCA
 134 #define DMA_CNT_7               0xCE
 135
 136 #define DMA_PAGE_0              0x87    /* DMA page registers */
 137 #define DMA_PAGE_1              0x83
 138 #define DMA_PAGE_2              0x81
 139 #define DMA_PAGE_3              0x82
 140 #define DMA_PAGE_5              0x8B
 141 #define DMA_PAGE_6              0x89
 142 #define DMA_PAGE_7              0x8A
 143
 144 /* I/O to memory, no autoinit, increment, single mode */
 145 #define DMA_MODE_READ           0x44
 146 /* memory to I/O, no autoinit, increment, single mode */
 147 #define DMA_MODE_WRITE          0x48
 148 /* pass thru DREQ->HRQ, DACK<-HLDA only */
 149 #define DMA_MODE_CASCADE        0xC0
 150
 151 #define DMA_AUTOINIT            0x10
 152
 153
 154 extern spinlock_t  dma_spin_lock;
 155
 156 static inline unsigned long claim_dma_lock(void)
 157 {
 158         unsigned long flags;
 159         spin_lock_irqsave(&dma_spin_lock, flags);
 160         return flags;
 161 }
 162
 163 static inline void release_dma_lock(unsigned long flags)
 164 {
 165         spin_unlock_irqrestore(&dma_spin_lock, flags);
 166 }
 167
 168 /* enable/disable a specific DMA channel */
 169 static inline void enable_dma(unsigned int dmanr)
 170 {
 171         if (dmanr <= 3)
 172                 dma_outb(dmanr, DMA1_MASK_REG);
 173         else
 174                 dma_outb(dmanr & 3, DMA2_MASK_REG);
 175 }
 176
 177 static inline void disable_dma(unsigned int dmanr)
 178 {
 179         if (dmanr <= 3)
 180                 dma_outb(dmanr | 4, DMA1_MASK_REG);
 181         else
 182                 dma_outb((dmanr & 3) | 4, DMA2_MASK_REG);
 183 }
 184
 185 /* Clear the 'DMA Pointer Flip Flop'.
 186  * Write 0 for LSB/MSB, 1 for MSB/LSB access.
 187  * Use this once to initialize the FF to a known state.
 188  * After that, keep track of it. :-)
 189  * --- In order to do that, the DMA routines below should ---
 190  * --- only be used while holding the DMA lock ! ---
 191  */
 192 static inline void clear_dma_ff(unsigned int dmanr)
 193 {
 194         if (dmanr <= 3)
 195                 dma_outb(0, DMA1_CLEAR_FF_REG);
 196         else
 197                 dma_outb(0, DMA2_CLEAR_FF_REG);
 198 }
 199
 200 /* set mode (above) for a specific DMA channel */
 201 static inline void set_dma_mode(unsigned int dmanr, char mode)
 202 {
 203         if (dmanr <= 3)
 204                 dma_outb(mode | dmanr, DMA1_MODE_REG);
 205         else
 206                 dma_outb(mode | (dmanr & 3), DMA2_MODE_REG);
 207 }
 208
 209 /* Set only the page register bits of the transfer address.
 210  * This is used for successive transfers when we know the contents of
 211  * the lower 16 bits of the DMA current address register, but a 64k boundary
 212  * may have been crossed.
 213  */
 214 static inline void set_dma_page(unsigned int dmanr, char pagenr)
 215 {
 216         switch (dmanr) {
 217         case 0:
 218                 dma_outb(pagenr, DMA_PAGE_0);
 219                 break;
 220         case 1:
 221                 dma_outb(pagenr, DMA_PAGE_1);
 222                 break;
 223         case 2:
 224                 dma_outb(pagenr, DMA_PAGE_2);
 225                 break;
 226         case 3:
 227                 dma_outb(pagenr, DMA_PAGE_3);
 228                 break;
 229         case 5:
 230                 dma_outb(pagenr & 0xfe, DMA_PAGE_5);
 231                 break;
 232         case 6:
 233                 dma_outb(pagenr & 0xfe, DMA_PAGE_6);
 234                 break;
 235         case 7:
 236                 dma_outb(pagenr & 0xfe, DMA_PAGE_7);
 237                 break;
 238         }
 239 }
 240
 241
 242 /* Set transfer address & page bits for specific DMA channel.
 243  * Assumes dma flipflop is clear.
 244  */
 245 static inline void set_dma_addr(unsigned int dmanr, unsigned int a)
 246 {
 247         set_dma_page(dmanr, a>>16);
 248         if (dmanr <= 3)  {
 249                 dma_outb(a & 0xff, ((dmanr & 3) << 1) + IO_DMA1_BASE);
 250                 dma_outb((a >> 8) & 0xff, ((dmanr & 3) << 1) + IO_DMA1_BASE);
 251         }  else  {
 252                 dma_outb((a >> 1) & 0xff, ((dmanr & 3) << 2) + IO_DMA2_BASE);
 253                 dma_outb((a >> 9) & 0xff, ((dmanr & 3) << 2) + IO_DMA2_BASE);
 254         }
 255 }
 256
 257
 258 /* Set transfer size (max 64k for DMA0..3, 128k for DMA5..7) for
 259  * a specific DMA channel.
 260  * You must ensure the parameters are valid.
 261  * NOTE: from a manual: "the number of transfers is one more
 262  * than the initial word count"! This is taken into account.
 263  * Assumes dma flip-flop is clear.
 264  * NOTE 2: "count" represents _bytes_ and must be even for channels 5-7.
 265  */
 266 static inline void set_dma_count(unsigned int dmanr, unsigned int count)
 267 {
 268         count--;
 269         if (dmanr <= 3)  {
 270                 dma_outb(count & 0xff, ((dmanr & 3) << 1) + 1 + IO_DMA1_BASE);
 271                 dma_outb((count >> 8) & 0xff,
 272                          ((dmanr & 3) << 1) + 1 + IO_DMA1_BASE);
 273         } else {
 274                 dma_outb((count >> 1) & 0xff,
 275                          ((dmanr & 3) << 2) + 2 + IO_DMA2_BASE);
 276                 dma_outb((count >> 9) & 0xff,
 277                          ((dmanr & 3) << 2) + 2 + IO_DMA2_BASE);
 278         }
 279 }
 280
 281
 282 /* Get DMA residue count. After a DMA transfer, this
 283  * should return zero. Reading this while a DMA transfer is
 284  * still in progress will return unpredictable results.
 285  * If called before the channel has been used, it may return 1.
 286  * Otherwise, it returns the number of _bytes_ left to transfer.
 287  *
 288  * Assumes DMA flip-flop is clear.
 289  */
 290 static inline int get_dma_residue(unsigned int dmanr)
 291 {
 292         unsigned int io_port;
 293         /* using short to get 16-bit wrap around */
 294         unsigned short count;
 295
 296         io_port = (dmanr <= 3) ? ((dmanr & 3) << 1) + 1 + IO_DMA1_BASE
 297                 : ((dmanr & 3) << 2) + 2 + IO_DMA2_BASE;
 298
 299         count = 1 + dma_inb(io_port);
 300         count += dma_inb(io_port) << 8;
 301
 302         return (dmanr <= 3) ? count : (count << 1);
 303 }
 304
 305
 306 /* These are in kernel/dma.c: */
 307 extern int request_dma(unsigned int dmanr, const char *device_id);
 308 extern void free_dma(unsigned int dmanr);
 309
 310 /* From PCI */
 311
 312 #ifdef CONFIG_PCI
 313 extern int isa_dma_bridge_buggy;
 314 #else
 315 #define isa_dma_bridge_buggy    (0)
 316 #endif
 317
 318 #endif /* ASM_X86__DMA_H */