arch/x86/include/asm/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
  14 #ifdef HAVE_REALLY_SLOW_DMA_CONTROLLER
  15 #define dma_outb        outb_p
  16 #else
  17 #define dma_outb        outb
  18 #endif
  19
  20 #define dma_inb         inb
  21
  22 /*
  23  * NOTES about DMA transfers:
  24  *
  25  *  controller 1: channels 0-3, byte operations, ports 00-1F
  26  *  controller 2: channels 4-7, word operations, ports C0-DF
  27  *
  28  *  - ALL registers are 8 bits only, regardless of transfer size
  29  *  - channel 4 is not used - cascades 1 into 2.
  30  *  - channels 0-3 are byte - addresses/counts are for physical bytes
  31  *  - channels 5-7 are word - addresses/counts are for physical words
  32  *  - transfers must not cross physical 64K (0-3) or 128K (5-7) boundaries
  33  *  - transfer count loaded to registers is 1 less than actual count
  34  *  - controller 2 offsets are all even (2x offsets for controller 1)
  35  *  - page registers for 5-7 don't use data bit 0, represent 128K pages
  36  *  - page registers for 0-3 use bit 0, represent 64K pages
  37  *
  38  * DMA transfers are limited to the lower 16MB of _physical_ memory.
  39  * Note that addresses loaded into registers must be _physical_ addresses,
  40  * not logical addresses (which may differ if paging is active).
  41  *
  42  *  Address mapping for channels 0-3:
  43  *
  44  *   A23 ... A16 A15 ... A8  A7 ... A0    (Physical addresses)
  45  *    |  ...  |   |  ... |   |  ... |
  46  *    |  ...  |   |  ... |   |  ... |
  47  *    |  ...  |   |  ... |   |  ... |
  48  *   P7  ...  P0  A7 ... A0  A7 ... A0
  49  * |    Page    | Addr MSB | Addr LSB |   (DMA registers)
  50  *
  51  *  Address mapping for channels 5-7:
  52  *
  53  *   A23 ... A17 A16 A15 ... A9 A8 A7 ... A1 A0    (Physical addresses)
  54  *    |  ...  |   \   \   ... \  \  \  ... \  \
  55  *    |  ...  |    \   \   ... \  \  \  ... \  (not used)
  56  *    |  ...  |     \   \   ... \  \  \  ... \
  57  *   P7  ...  P1 (0) A7 A6  ... A0 A7 A6 ... A0
  58  * |      Page      |  Addr MSB   |  Addr LSB  |   (DMA registers)
  59  *
  60  * Again, channels 5-7 transfer _physical_ words (16 bits), so addresses
  61  * and counts _must_ be word-aligned (the lowest address bit is _ignored_ at
  62  * the hardware level, so odd-byte transfers aren't possible).
  63  *
  64  * Transfer count (_not # bytes_) is limited to 64K, represented as actual
  65  * count - 1 : 64K => 0xFFFF, 1 => 0x0000.  Thus, count is always 1 or more,
  66  * and up to 128K bytes may be transferred on channels 5-7 in one operation.
  67  *
  68  */
  69
  70 #define MAX_DMA_CHANNELS        8
  71
  72 /* 16MB ISA DMA zone */
  73 #define MAX_DMA_PFN   ((16UL * 1024 * 1024) >> PAGE_SHIFT)
  74
  75 /* 4GB broken PCI/AGP hardware bus master zone */
  76 #define MAX_DMA32_PFN ((4UL * 1024 * 1024 * 1024) >> PAGE_SHIFT)
  77
  78 #ifdef CONFIG_X86_32
  79 /* The maximum address that we can perform a DMA transfer to on this platform */
  80 #define MAX_DMA_ADDRESS      (PAGE_OFFSET + 0x1000000)
  81 #else
  82 /* Compat define for old dma zone */
  83 #define MAX_DMA_ADDRESS ((unsigned long)__va(MAX_DMA_PFN << PAGE_SHIFT))
  84 #endif
  85
  86 /* 8237 DMA controllers */
  87 #define IO_DMA1_BASE    0x00    /* 8 bit slave DMA, channels 0..3 */
  88 #define IO_DMA2_BASE    0xC0    /* 16 bit master DMA, ch 4(=slave input)..7 */
  89
  90 /* DMA controller registers */
  91 #define DMA1_CMD_REG            0x08    /* command register (w) */
  92 #define DMA1_STAT_REG           0x08    /* status register (r) */
  93 #define DMA1_REQ_REG            0x09    /* request register (w) */
  94 #define DMA1_MASK_REG           0x0A    /* single-channel mask (w) */
  95 #define DMA1_MODE_REG           0x0B    /* mode register (w) */
  96 #define DMA1_CLEAR_FF_REG       0x0C    /* clear pointer flip-flop (w) */
  97 #define DMA1_TEMP_REG           0x0D    /* Temporary Register (r) */
  98 #define DMA1_RESET_REG          0x0D    /* Master Clear (w) */
  99 #define DMA1_CLR_MASK_REG       0x0E    /* Clear Mask */
 100 #define DMA1_MASK_ALL_REG       0x0F    /* all-channels mask (w) */
 101
 102 #define DMA2_CMD_REG            0xD0    /* command register (w) */
 103 #define DMA2_STAT_REG           0xD0    /* status register (r) */
 104 #define DMA2_REQ_REG            0xD2    /* request register (w) */
 105 #define DMA2_MASK_REG           0xD4    /* single-channel mask (w) */
 106 #define DMA2_MODE_REG           0xD6    /* mode register (w) */
 107 #define DMA2_CLEAR_FF_REG       0xD8    /* clear pointer flip-flop (w) */
 108 #define DMA2_TEMP_REG           0xDA    /* Temporary Register (r) */
 109 #define DMA2_RESET_REG          0xDA    /* Master Clear (w) */
 110 #define DMA2_CLR_MASK_REG       0xDC    /* Clear Mask */
 111 #define DMA2_MASK_ALL_REG       0xDE    /* all-channels mask (w) */
 112
 113 #define DMA_ADDR_0              0x00    /* DMA address registers */
 114 #define DMA_ADDR_1              0x02
 115 #define DMA_ADDR_2              0x04
 116 #define DMA_ADDR_3              0x06
 117 #define DMA_ADDR_4              0xC0
 118 #define DMA_ADDR_5              0xC4
 119 #define DMA_ADDR_6              0xC8
 120 #define DMA_ADDR_7              0xCC
 121
 122 #define DMA_CNT_0               0x01    /* DMA count registers */
 123 #define DMA_CNT_1               0x03
 124 #define DMA_CNT_2               0x05
 125 #define DMA_CNT_3               0x07
 126 #define DMA_CNT_4               0xC2
 127 #define DMA_CNT_5               0xC6
 128 #define DMA_CNT_6               0xCA
 129 #define DMA_CNT_7               0xCE
 130
 131 #define DMA_PAGE_0              0x87    /* DMA page registers */
 132 #define DMA_PAGE_1              0x83
 133 #define DMA_PAGE_2              0x81
 134 #define DMA_PAGE_3              0x82
 135 #define DMA_PAGE_5              0x8B
 136 #define DMA_PAGE_6              0x89
 137 #define DMA_PAGE_7              0x8A
 138
 139 /* I/O to memory, no autoinit, increment, single mode */
 140 #define DMA_MODE_READ           0x44
 141 /* memory to I/O, no autoinit, increment, single mode */
 142 #define DMA_MODE_WRITE          0x48
 143 /* pass thru DREQ->HRQ, DACK<-HLDA only */
 144 #define DMA_MODE_CASCADE        0xC0
 145
 146 #define DMA_AUTOINIT            0x10
 147
 148
 149 #ifdef CONFIG_ISA_DMA_API
 150 extern spinlock_t  dma_spin_lock;
 151
 152 static inline unsigned long claim_dma_lock(void)
 153 {
 154         unsigned long flags;
 155         spin_lock_irqsave(&dma_spin_lock, flags);
 156         return flags;
 157 }
 158
 159 static inline void release_dma_lock(unsigned long flags)
 160 {
 161         spin_unlock_irqrestore(&dma_spin_lock, flags);
 162 }
 163 #endif /* CONFIG_ISA_DMA_API */
 164
 165 /* enable/disable a specific DMA channel */
 166 static inline void enable_dma(unsigned int dmanr)
 167 {
 168         if (dmanr <= 3)
 169                 dma_outb(dmanr, DMA1_MASK_REG);
 170         else
 171                 dma_outb(dmanr & 3, DMA2_MASK_REG);
 172 }
 173
 174 static inline void disable_dma(unsigned int dmanr)
 175 {
 176         if (dmanr <= 3)
 177                 dma_outb(dmanr | 4, DMA1_MASK_REG);
 178         else
 179                 dma_outb((dmanr & 3) | 4, DMA2_MASK_REG);
 180 }
 181
 182 /* Clear the 'DMA Pointer Flip Flop'.
 183  * Write 0 for LSB/MSB, 1 for MSB/LSB access.
 184  * Use this once to initialize the FF to a known state.
 185  * After that, keep track of it. :-)
 186  * --- In order to do that, the DMA routines below should ---
 187  * --- only be used while holding the DMA lock ! ---
 188  */
 189 static inline void clear_dma_ff(unsigned int dmanr)
 190 {
 191         if (dmanr <= 3)
 192                 dma_outb(0, DMA1_CLEAR_FF_REG);
 193         else
 194                 dma_outb(0, DMA2_CLEAR_FF_REG);
 195 }
 196
 197 /* set mode (above) for a specific DMA channel */
 198 static inline void set_dma_mode(unsigned int dmanr, char mode)
 199 {
 200         if (dmanr <= 3)
 201                 dma_outb(mode | dmanr, DMA1_MODE_REG);
 202         else
 203                 dma_outb(mode | (dmanr & 3), DMA2_MODE_REG);
 204 }
 205
 206 /* Set only the page register bits of the transfer address.
 207  * This is used for successive transfers when we know the contents of
 208  * the lower 16 bits of the DMA current address register, but a 64k boundary
 209  * may have been crossed.
 210  */
 211 static inline void set_dma_page(unsigned int dmanr, char pagenr)
 212 {
 213         switch (dmanr) {
 214         case 0:
 215                 dma_outb(pagenr, DMA_PAGE_0);
 216                 break;
 217         case 1:
 218                 dma_outb(pagenr, DMA_PAGE_1);
 219                 break;
 220         case 2:
 221                 dma_outb(pagenr, DMA_PAGE_2);
 222                 break;
 223         case 3:
 224                 dma_outb(pagenr, DMA_PAGE_3);
 225                 break;
 226         case 5:
 227                 dma_outb(pagenr & 0xfe, DMA_PAGE_5);
 228                 break;
 229         case 6:
 230                 dma_outb(pagenr & 0xfe, DMA_PAGE_6);
 231                 break;
 232         case 7:
 233                 dma_outb(pagenr & 0xfe, DMA_PAGE_7);
 234                 break;
 235         }
 236 }
 237
 238
 239 /* Set transfer address & page bits for specific DMA channel.
 240  * Assumes dma flipflop is clear.
 241  */
 242 static inline void set_dma_addr(unsigned int dmanr, unsigned int a)
 243 {
 244         set_dma_page(dmanr, a>>16);
 245         if (dmanr <= 3)  {
 246                 dma_outb(a & 0xff, ((dmanr & 3) << 1) + IO_DMA1_BASE);
 247                 dma_outb((a >> 8) & 0xff, ((dmanr & 3) << 1) + IO_DMA1_BASE);
 248         }  else  {
 249                 dma_outb((a >> 1) & 0xff, ((dmanr & 3) << 2) + IO_DMA2_BASE);
 250                 dma_outb((a >> 9) & 0xff, ((dmanr & 3) << 2) + IO_DMA2_BASE);
 251         }
 252 }
 253
 254
 255 /* Set transfer size (max 64k for DMA0..3, 128k for DMA5..7) for
 256  * a specific DMA channel.
 257  * You must ensure the parameters are valid.
 258  * NOTE: from a manual: "the number of transfers is one more
 259  * than the initial word count"! This is taken into account.
 260  * Assumes dma flip-flop is clear.
 261  * NOTE 2: "count" represents _bytes_ and must be even for channels 5-7.
 262  */
 263 static inline void set_dma_count(unsigned int dmanr, unsigned int count)
 264 {
 265         count--;
 266         if (dmanr <= 3)  {
 267                 dma_outb(count & 0xff, ((dmanr & 3) << 1) + 1 + IO_DMA1_BASE);
 268                 dma_outb((count >> 8) & 0xff,
 269                          ((dmanr & 3) << 1) + 1 + IO_DMA1_BASE);
 270         } else {
 271                 dma_outb((count >> 1) & 0xff,
 272                          ((dmanr & 3) << 2) + 2 + IO_DMA2_BASE);
 273                 dma_outb((count >> 9) & 0xff,
 274                          ((dmanr & 3) << 2) + 2 + IO_DMA2_BASE);
 275         }
 276 }
 277
 278
 279 /* Get DMA residue count. After a DMA transfer, this
 280  * should return zero. Reading this while a DMA transfer is
 281  * still in progress will return unpredictable results.
 282  * If called before the channel has been used, it may return 1.
 283  * Otherwise, it returns the number of _bytes_ left to transfer.
 284  *
 285  * Assumes DMA flip-flop is clear.
 286  */
 287 static inline int get_dma_residue(unsigned int dmanr)
 288 {
 289         unsigned int io_port;
 290         /* using short to get 16-bit wrap around */
 291         unsigned short count;
 292
 293         io_port = (dmanr <= 3) ? ((dmanr & 3) << 1) + 1 + IO_DMA1_BASE
 294                 : ((dmanr & 3) << 2) + 2 + IO_DMA2_BASE;
 295
 296         count = 1 + dma_inb(io_port);
 297         count += dma_inb(io_port) << 8;
 298
 299         return (dmanr <= 3) ? count : (count << 1);
 300 }
 301
 302
 303 /* These are in kernel/dma.c because x86 uses CONFIG_GENERIC_ISA_DMA */
 304 #ifdef CONFIG_ISA_DMA_API
 305 extern int request_dma(unsigned int dmanr, const char *device_id);
 306 extern void free_dma(unsigned int dmanr);
 307 #endif
 308
 309 /* From PCI */
 310
 311 #ifdef CONFIG_PCI
 312 extern int isa_dma_bridge_buggy;
 313 #else
 314 #define isa_dma_bridge_buggy    (0)
 315 #endif
 316
 317 #endif /* _ASM_X86_DMA_H */