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
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