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