1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * linux/include/asm/dma.h: Defines for using and allocating dma channels. 4 * Written by Hennus Bergman, 1992. 5 * High DMA channel support & info by Hannu Savolainen 6 * and John Boyd, Nov. 1992. 7 */ 8 9 #ifndef _ASM_X86_DMA_H 10 #define _ASM_X86_DMA_H 11 12 #include <linux/spinlock.h> /* And spinlocks */ 13 #include <asm/io.h> /* need byte IO */ 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 /* 16MB ISA DMA zone */ 74 #define MAX_DMA_PFN ((16UL * 1024 * 1024) >> PAGE_SHIFT) 75 76 /* 4GB broken PCI/AGP hardware bus master zone */ 77 #define MAX_DMA32_PFN (1UL << (32 - PAGE_SHIFT)) 78 79 #ifdef CONFIG_X86_32 80 /* The maximum address that we can perform a DMA transfer to on this platform */ 81 #define MAX_DMA_ADDRESS (PAGE_OFFSET + 0x1000000) 82 #else 83 /* Compat define for old dma zone */ 84 #define MAX_DMA_ADDRESS ((unsigned long)__va(MAX_DMA_PFN << PAGE_SHIFT)) 85 #endif 86 87 /* 8237 DMA controllers */ 88 #define IO_DMA1_BASE 0x00 /* 8 bit slave DMA, channels 0..3 */ 89 #define IO_DMA2_BASE 0xC0 /* 16 bit master DMA, ch 4(=slave input)..7 */ 90 91 /* DMA controller registers */ 92 #define DMA1_CMD_REG 0x08 /* command register (w) */ 93 #define DMA1_STAT_REG 0x08 /* status register (r) */ 94 #define DMA1_REQ_REG 0x09 /* request register (w) */ 95 #define DMA1_MASK_REG 0x0A /* single-channel mask (w) */ 96 #define DMA1_MODE_REG 0x0B /* mode register (w) */ 97 #define DMA1_CLEAR_FF_REG 0x0C /* clear pointer flip-flop (w) */ 98 #define DMA1_TEMP_REG 0x0D /* Temporary Register (r) */ 99 #define DMA1_RESET_REG 0x0D /* Master Clear (w) */ 100 #define DMA1_CLR_MASK_REG 0x0E /* Clear Mask */ 101 #define DMA1_MASK_ALL_REG 0x0F /* all-channels mask (w) */ 102 103 #define DMA2_CMD_REG 0xD0 /* command register (w) */ 104 #define DMA2_STAT_REG 0xD0 /* status register (r) */ 105 #define DMA2_REQ_REG 0xD2 /* request register (w) */ 106 #define DMA2_MASK_REG 0xD4 /* single-channel mask (w) */ 107 #define DMA2_MODE_REG 0xD6 /* mode register (w) */ 108 #define DMA2_CLEAR_FF_REG 0xD8 /* clear pointer flip-flop (w) */ 109 #define DMA2_TEMP_REG 0xDA /* Temporary Register (r) */ 110 #define DMA2_RESET_REG 0xDA /* Master Clear (w) */ 111 #define DMA2_CLR_MASK_REG 0xDC /* Clear Mask */ 112 #define DMA2_MASK_ALL_REG 0xDE /* all-channels mask (w) */ 113 114 #define DMA_ADDR_0 0x00 /* DMA address registers */ 115 #define DMA_ADDR_1 0x02 116 #define DMA_ADDR_2 0x04 117 #define DMA_ADDR_3 0x06 118 #define DMA_ADDR_4 0xC0 119 #define DMA_ADDR_5 0xC4 120 #define DMA_ADDR_6 0xC8 121 #define DMA_ADDR_7 0xCC 122 123 #define DMA_CNT_0 0x01 /* DMA count registers */ 124 #define DMA_CNT_1 0x03 125 #define DMA_CNT_2 0x05 126 #define DMA_CNT_3 0x07 127 #define DMA_CNT_4 0xC2 128 #define DMA_CNT_5 0xC6 129 #define DMA_CNT_6 0xCA 130 #define DMA_CNT_7 0xCE 131 132 #define DMA_PAGE_0 0x87 /* DMA page registers */ 133 #define DMA_PAGE_1 0x83 134 #define DMA_PAGE_2 0x81 135 #define DMA_PAGE_3 0x82 136 #define DMA_PAGE_5 0x8B 137 #define DMA_PAGE_6 0x89 138 #define DMA_PAGE_7 0x8A 139 140 /* I/O to memory, no autoinit, increment, single mode */ 141 #define DMA_MODE_READ 0x44 142 /* memory to I/O, no autoinit, increment, single mode */ 143 #define DMA_MODE_WRITE 0x48 144 /* pass thru DREQ->HRQ, DACK<-HLDA only */ 145 #define DMA_MODE_CASCADE 0xC0 146 147 #define DMA_AUTOINIT 0x10 148 149 150 #ifdef CONFIG_ISA_DMA_API 151 extern spinlock_t dma_spin_lock; 152 153 static inline unsigned long claim_dma_lock(void) 154 { 155 unsigned long flags; 156 spin_lock_irqsave(&dma_spin_lock, flags); 157 return flags; 158 } 159 160 static inline void release_dma_lock(unsigned long flags) 161 { 162 spin_unlock_irqrestore(&dma_spin_lock, flags); 163 } 164 #endif /* CONFIG_ISA_DMA_API */ 165 166 /* enable/disable a specific DMA channel */ 167 static inline void enable_dma(unsigned int dmanr) 168 { 169 if (dmanr <= 3) 170 dma_outb(dmanr, DMA1_MASK_REG); 171 else 172 dma_outb(dmanr & 3, DMA2_MASK_REG); 173 } 174 175 static inline void disable_dma(unsigned int dmanr) 176 { 177 if (dmanr <= 3) 178 dma_outb(dmanr | 4, DMA1_MASK_REG); 179 else 180 dma_outb((dmanr & 3) | 4, DMA2_MASK_REG); 181 } 182 183 /* Clear the 'DMA Pointer Flip Flop'. 184 * Write 0 for LSB/MSB, 1 for MSB/LSB access. 185 * Use this once to initialize the FF to a known state. 186 * After that, keep track of it. :-) 187 * --- In order to do that, the DMA routines below should --- 188 * --- only be used while holding the DMA lock ! --- 189 */ 190 static inline void clear_dma_ff(unsigned int dmanr) 191 { 192 if (dmanr <= 3) 193 dma_outb(0, DMA1_CLEAR_FF_REG); 194 else 195 dma_outb(0, DMA2_CLEAR_FF_REG); 196 } 197 198 /* set mode (above) for a specific DMA channel */ 199 static inline void set_dma_mode(unsigned int dmanr, char mode) 200 { 201 if (dmanr <= 3) 202 dma_outb(mode | dmanr, DMA1_MODE_REG); 203 else 204 dma_outb(mode | (dmanr & 3), DMA2_MODE_REG); 205 } 206 207 /* Set only the page register bits of the transfer address. 208 * This is used for successive transfers when we know the contents of 209 * the lower 16 bits of the DMA current address register, but a 64k boundary 210 * may have been crossed. 211 */ 212 static inline void set_dma_page(unsigned int dmanr, char pagenr) 213 { 214 switch (dmanr) { 215 case 0: 216 dma_outb(pagenr, DMA_PAGE_0); 217 break; 218 case 1: 219 dma_outb(pagenr, DMA_PAGE_1); 220 break; 221 case 2: 222 dma_outb(pagenr, DMA_PAGE_2); 223 break; 224 case 3: 225 dma_outb(pagenr, DMA_PAGE_3); 226 break; 227 case 5: 228 dma_outb(pagenr & 0xfe, DMA_PAGE_5); 229 break; 230 case 6: 231 dma_outb(pagenr & 0xfe, DMA_PAGE_6); 232 break; 233 case 7: 234 dma_outb(pagenr & 0xfe, DMA_PAGE_7); 235 break; 236 } 237 } 238 239 240 /* Set transfer address & page bits for specific DMA channel. 241 * Assumes dma flipflop is clear. 242 */ 243 static inline void set_dma_addr(unsigned int dmanr, unsigned int a) 244 { 245 set_dma_page(dmanr, a>>16); 246 if (dmanr <= 3) { 247 dma_outb(a & 0xff, ((dmanr & 3) << 1) + IO_DMA1_BASE); 248 dma_outb((a >> 8) & 0xff, ((dmanr & 3) << 1) + IO_DMA1_BASE); 249 } else { 250 dma_outb((a >> 1) & 0xff, ((dmanr & 3) << 2) + IO_DMA2_BASE); 251 dma_outb((a >> 9) & 0xff, ((dmanr & 3) << 2) + IO_DMA2_BASE); 252 } 253 } 254 255 256 /* Set transfer size (max 64k for DMA0..3, 128k for DMA5..7) for 257 * a specific DMA channel. 258 * You must ensure the parameters are valid. 259 * NOTE: from a manual: "the number of transfers is one more 260 * than the initial word count"! This is taken into account. 261 * Assumes dma flip-flop is clear. 262 * NOTE 2: "count" represents _bytes_ and must be even for channels 5-7. 263 */ 264 static inline void set_dma_count(unsigned int dmanr, unsigned int count) 265 { 266 count--; 267 if (dmanr <= 3) { 268 dma_outb(count & 0xff, ((dmanr & 3) << 1) + 1 + IO_DMA1_BASE); 269 dma_outb((count >> 8) & 0xff, 270 ((dmanr & 3) << 1) + 1 + IO_DMA1_BASE); 271 } else { 272 dma_outb((count >> 1) & 0xff, 273 ((dmanr & 3) << 2) + 2 + IO_DMA2_BASE); 274 dma_outb((count >> 9) & 0xff, 275 ((dmanr & 3) << 2) + 2 + IO_DMA2_BASE); 276 } 277 } 278 279 280 /* Get DMA residue count. After a DMA transfer, this 281 * should return zero. Reading this while a DMA transfer is 282 * still in progress will return unpredictable results. 283 * If called before the channel has been used, it may return 1. 284 * Otherwise, it returns the number of _bytes_ left to transfer. 285 * 286 * Assumes DMA flip-flop is clear. 287 */ 288 static inline int get_dma_residue(unsigned int dmanr) 289 { 290 unsigned int io_port; 291 /* using short to get 16-bit wrap around */ 292 unsigned short count; 293 294 io_port = (dmanr <= 3) ? ((dmanr & 3) << 1) + 1 + IO_DMA1_BASE 295 : ((dmanr & 3) << 2) + 2 + IO_DMA2_BASE; 296 297 count = 1 + dma_inb(io_port); 298 count += dma_inb(io_port) << 8; 299 300 return (dmanr <= 3) ? count : (count << 1); 301 } 302 303 304 /* These are in kernel/dma.c because x86 uses CONFIG_GENERIC_ISA_DMA */ 305 #ifdef CONFIG_ISA_DMA_API 306 extern int request_dma(unsigned int dmanr, const char *device_id); 307 extern void free_dma(unsigned int dmanr); 308 #endif 309 310 #endif /* _ASM_X86_DMA_H */ 311