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1 /* $Id: dma.h,v 1.7 1992/12/14 00:29:34 root Exp root $
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_DMA_H
9 #define _ASM_DMA_H
10
11 #include <asm/io.h> /* need byte IO */
12
13
14 #ifdef HAVE_REALLY_SLOW_DMA_CONTROLLER
15 #define outb outb_p
16 #endif
17
18 /*
19 * NOTES about DMA transfers:
20 *
21 * controller 1: channels 0-3, byte operations, ports 00-1F
22 * controller 2: channels 4-7, word operations, ports C0-DF
23 *
24 * - ALL registers are 8 bits only, regardless of transfer size
25 * - channel 4 is not used - cascades 1 into 2.
26 * - channels 0-3 are byte - addresses/counts are for physical bytes
27 * - channels 5-7 are word - addresses/counts are for physical words
28 * - transfers must not cross physical 64K (0-3) or 128K (5-7) boundaries
29 * - transfer count loaded to registers is 1 less than actual count
30 * - controller 2 offsets are all even (2x offsets for controller 1)
31 * - page registers for 5-7 don't use data bit 0, represent 128K pages
32 * - page registers for 0-3 use bit 0, represent 64K pages
33 *
34 * DMA transfers are limited to the lower 16MB of _physical_ memory.
35 * Note that addresses loaded into registers must be _physical_ addresses,
36 * not logical addresses (which may differ if paging is active).
37 *
38 * Address mapping for channels 0-3:
39 *
40 * A23 ... A16 A15 ... A8 A7 ... A0 (Physical addresses)
41 * | ... | | ... | | ... |
42 * | ... | | ... | | ... |
43 * | ... | | ... | | ... |
44 * P7 ... P0 A7 ... A0 A7 ... A0
45 * | Page | Addr MSB | Addr LSB | (DMA registers)
46 *
47 * Address mapping for channels 5-7:
48 *
49 * A23 ... A17 A16 A15 ... A9 A8 A7 ... A1 A0 (Physical addresses)
50 * | ... | \ \ ... \ \ \ ... \ \
51 * | ... | \ \ ... \ \ \ ... \ (not used)
52 * | ... | \ \ ... \ \ \ ... \
53 * P7 ... P1 (0) A7 A6 ... A0 A7 A6 ... A0
54 * | Page | Addr MSB | Addr LSB | (DMA registers)
55 *
56 * Again, channels 5-7 transfer _physical_ words (16 bits), so addresses
57 * and counts _must_ be word-aligned (the lowest address bit is _ignored_ at
58 * the hardware level, so odd-byte transfers aren't possible).
59 *
60 * Transfer count (_not # bytes_) is limited to 64K, represented as actual
61 * count - 1 : 64K => 0xFFFF, 1 => 0x0000. Thus, count is always 1 or more,
62 * and up to 128K bytes may be transferred on channels 5-7 in one operation.
63 *
64 */
65
66 #define MAX_DMA_CHANNELS 8
67
68 /* 8237 DMA controllers */
69 #define IO_DMA1_BASE 0x00 /* 8 bit slave DMA, channels 0..3 */
70 #define IO_DMA2_BASE 0xC0 /* 16 bit master DMA, ch 4(=slave input)..7 */
71
72 /* DMA controller registers */
73 #define DMA1_CMD_REG 0x08 /* command register (w) */
74 #define DMA1_STAT_REG 0x08 /* status register (r) */
75 #define DMA1_REQ_REG 0x09 /* request register (w) */
76 #define DMA1_MASK_REG 0x0A /* single-channel mask (w) */
77 #define DMA1_MODE_REG 0x0B /* mode register (w) */
78 #define DMA1_CLEAR_FF_REG 0x0C /* clear pointer flip-flop (w) */
79 #define DMA1_TEMP_REG 0x0D /* Temporary Register (r) */
80 #define DMA1_RESET_REG 0x0D /* Master Clear (w) */
81 #define DMA1_CLR_MASK_REG 0x0E /* Clear Mask */
82 #define DMA1_MASK_ALL_REG 0x0F /* all-channels mask (w) */
83
84 #define DMA2_CMD_REG 0xD0 /* command register (w) */
85 #define DMA2_STAT_REG 0xD0 /* status register (r) */
86 #define DMA2_REQ_REG 0xD2 /* request register (w) */
87 #define DMA2_MASK_REG 0xD4 /* single-channel mask (w) */
88 #define DMA2_MODE_REG 0xD6 /* mode register (w) */
89 #define DMA2_CLEAR_FF_REG 0xD8 /* clear pointer flip-flop (w) */
90 #define DMA2_TEMP_REG 0xDA /* Temporary Register (r) */
91 #define DMA2_RESET_REG 0xDA /* Master Clear (w) */
92 #define DMA2_CLR_MASK_REG 0xDC /* Clear Mask */
93 #define DMA2_MASK_ALL_REG 0xDE /* all-channels mask (w) */
94
95 #define DMA_ADDR_0 0x00 /* DMA address registers */
96 #define DMA_ADDR_1 0x02
97 #define DMA_ADDR_2 0x04
98 #define DMA_ADDR_3 0x06
99 #define DMA_ADDR_4 0xC0
100 #define DMA_ADDR_5 0xC4
101 #define DMA_ADDR_6 0xC8
102 #define DMA_ADDR_7 0xCC
103
104 #define DMA_CNT_0 0x01 /* DMA count registers */
105 #define DMA_CNT_1 0x03
106 #define DMA_CNT_2 0x05
107 #define DMA_CNT_3 0x07
108 #define DMA_CNT_4 0xC2
109 #define DMA_CNT_5 0xC6
110 #define DMA_CNT_6 0xCA
111 #define DMA_CNT_7 0xCE
112
113 #define DMA_PAGE_0 0x87 /* DMA page registers */
114 #define DMA_PAGE_1 0x83
115 #define DMA_PAGE_2 0x81
116 #define DMA_PAGE_3 0x82
117 #define DMA_PAGE_5 0x8B
118 #define DMA_PAGE_6 0x89
119 #define DMA_PAGE_7 0x8A
120
121 #define DMA_MODE_READ 0x44 /* I/O to memory, no autoinit, increment, single mode */
122 #define DMA_MODE_WRITE 0x48 /* memory to I/O, no autoinit, increment, single mode */
123 #define DMA_MODE_CASCADE 0xC0 /* pass thru DREQ->HRQ, DACK<-HLDA only */
124
125 /* enable/disable a specific DMA channel */
126 static __inline__ void enable_dma(unsigned int dmanr)
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127 {
128 if (dmanr<=3)
129 outb(dmanr, DMA1_MASK_REG);
130 else
131 outb(dmanr & 3, DMA2_MASK_REG);
132 }
133
134 static __inline__ void disable_dma(unsigned int dmanr)
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135 {
136 if (dmanr<=3)
137 outb(dmanr | 4, DMA1_MASK_REG);
138 else
139 outb((dmanr & 3) | 4, DMA2_MASK_REG);
140 }
141
142 /* Clear the 'DMA Pointer Flip Flop'.
143 * Write 0 for LSB/MSB, 1 for MSB/LSB access.
144 * Use this once to initialize the FF to a known state.
145 * After that, keep track of it. :-)
146 * --- In order to do that, the DMA routines below should ---
147 * --- only be used while interrupts are disabled! ---
148 */
149 static __inline__ void clear_dma_ff(unsigned int dmanr)
/* */
150 {
151 if (dmanr<=3)
152 outb(0, DMA1_CLEAR_FF_REG);
153 else
154 outb(0, DMA2_CLEAR_FF_REG);
155 }
156
157 /* set mode (above) for a specific DMA channel */
158 static __inline__ void set_dma_mode(unsigned int dmanr, char mode)
/* */
159 {
160 if (dmanr<=3)
161 outb(mode | dmanr, DMA1_MODE_REG);
162 else
163 outb(mode | (dmanr&3), DMA2_MODE_REG);
164 }
165
166 /* Set only the page register bits of the transfer address.
167 * This is used for successive transfers when we know the contents of
168 * the lower 16 bits of the DMA current address register, but a 64k boundary
169 * may have been crossed.
170 */
171 static __inline__ void set_dma_page(unsigned int dmanr, char pagenr)
/* */
172 {
173 switch(dmanr) {
174 case 0:
175 outb(pagenr, DMA_PAGE_0);
176 break;
177 case 1:
178 outb(pagenr, DMA_PAGE_1);
179 break;
180 case 2:
181 outb(pagenr, DMA_PAGE_2);
182 break;
183 case 3:
184 outb(pagenr, DMA_PAGE_3);
185 break;
186 case 5:
187 outb(pagenr & 0xfe, DMA_PAGE_5);
188 break;
189 case 6:
190 outb(pagenr & 0xfe, DMA_PAGE_6);
191 break;
192 case 7:
193 outb(pagenr & 0xfe, DMA_PAGE_7);
194 break;
195 }
196 }
197
198
199 /* Set transfer address & page bits for specific DMA channel.
200 * Assumes dma flipflop is clear.
201 */
202 static __inline__ void set_dma_addr(unsigned int dmanr, unsigned int a)
/* */
203 {
204 set_dma_page(dmanr, a>>16);
205 if (dmanr <= 3) {
206 outb( a & 0xff, ((dmanr&3)<<1) + IO_DMA1_BASE );
207 outb( (a>>8) & 0xff, ((dmanr&3)<<1) + IO_DMA1_BASE );
208 } else {
209 outb( (a>>1) & 0xff, ((dmanr&3)<<2) + IO_DMA2_BASE );
210 outb( (a>>9) & 0xff, ((dmanr&3)<<2) + IO_DMA2_BASE );
211 }
212 }
213
214
215 /* Set transfer size (max 64k for DMA1..3, 128k for DMA5..7) for
216 * a specific DMA channel.
217 * You must ensure the parameters are valid.
218 * NOTE: from a manual: "the number of transfers is one more
219 * than the initial word count"! This is taken into account.
220 * Assumes dma flip-flop is clear.
221 * NOTE 2: "count" represents _bytes_ and must be even for channels 5-7.
222 */
223 static __inline__ void set_dma_count(unsigned int dmanr, unsigned int count)
/* */
224 {
225 count--;
226 if (dmanr <= 3) {
227 outb( count & 0xff, ((dmanr&3)<<1) + 1 + IO_DMA1_BASE );
228 outb( (count>>8) & 0xff, ((dmanr&3)<<1) + 1 + IO_DMA1_BASE );
229 } else {
230 outb( (count>>1) & 0xff, ((dmanr&3)<<2) + 2 + IO_DMA2_BASE );
231 outb( (count>>9) & 0xff, ((dmanr&3)<<2) + 2 + IO_DMA2_BASE );
232 }
233 }
234
235
236 /* Get DMA residue count. After a DMA transfer, this
237 * should return zero. Reading this while a DMA transfer is
238 * still in progress will return unpredictable results.
239 * If called before the channel has been used, it may return 1.
240 * Otherwise, it returns the number of _bytes_ left to transfer.
241 *
242 * Assumes DMA flip-flop is clear.
243 */
244 static __inline__ int get_dma_residue(unsigned int dmanr)
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245 {
246 unsigned int io_port = (dmanr<=3)? ((dmanr&3)<<1) + 1 + IO_DMA1_BASE
247 : ((dmanr&3)<<2) + 2 + IO_DMA2_BASE;
248
249 /* using short to get 16-bit wrap around */
250 unsigned short count;
251
252 count = 1 + inb(io_port);
253 count += inb(io_port) << 8;
254
255 return (dmanr<=3)? count : (count<<1);
256 }
257
258
259 /* These are in kernel/dma.c: */
260 extern int request_dma(unsigned int dmanr); /* reserve a DMA channel */
261 extern void free_dma(unsigned int dmanr); /* release it again */
262
263
264 #endif /* _ASM_DMA_H */
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*/