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 * NOTE: all this is true *only* for ISA/EISA expansions on Mips boards
9 * and can only be used for expansion cards. Onboard DMA controllers, such
10 * as the R4030 on Jazz boards behave totally different!
11 */
12
13 #ifndef _ASM_DMA_H
14 #define _ASM_DMA_H
15
16 #include <asm/io.h> /* need byte IO */
17 #include <linux/spinlock.h> /* And spinlocks */
18 #include <linux/delay.h>
19
20
21 #ifdef HAVE_REALLY_SLOW_DMA_CONTROLLER
22 #define dma_outb outb_p
23 #else
24 #define dma_outb outb
25 #endif
26
27 #define dma_inb inb
28
29 /*
30 * NOTES about DMA transfers:
31 *
32 * controller 1: channels 0-3, byte operations, ports 00-1F
33 * controller 2: channels 4-7, word operations, ports C0-DF
34 *
35 * - ALL registers are 8 bits only, regardless of transfer size
36 * - channel 4 is not used - cascades 1 into 2.
37 * - channels 0-3 are byte - addresses/counts are for physical bytes
38 * - channels 5-7 are word - addresses/counts are for physical words
39 * - transfers must not cross physical 64K (0-3) or 128K (5-7) boundaries
40 * - transfer count loaded to registers is 1 less than actual count
41 * - controller 2 offsets are all even (2x offsets for controller 1)
42 * - page registers for 5-7 don't use data bit 0, represent 128K pages
43 * - page registers for 0-3 use bit 0, represent 64K pages
44 *
45 * DMA transfers are limited to the lower 16MB of _physical_ memory.
46 * Note that addresses loaded into registers must be _physical_ addresses,
47 * not logical addresses (which may differ if paging is active).
48 *
49 * Address mapping for channels 0-3:
50 *
51 * A23 ... A16 A15 ... A8 A7 ... A0 (Physical addresses)
52 * | ... | | ... | | ... |
53 * | ... | | ... | | ... |
54 * | ... | | ... | | ... |
55 * P7 ... P0 A7 ... A0 A7 ... A0
56 * | Page | Addr MSB | Addr LSB | (DMA registers)
57 *
58 * Address mapping for channels 5-7:
59 *
60 * A23 ... A17 A16 A15 ... A9 A8 A7 ... A1 A0 (Physical addresses)
61 * | ... | \ \ ... \ \ \ ... \ \
62 * | ... | \ \ ... \ \ \ ... \ (not used)
63 * | ... | \ \ ... \ \ \ ... \
64 * P7 ... P1 (0) A7 A6 ... A0 A7 A6 ... A0
65 * | Page | Addr MSB | Addr LSB | (DMA registers)
66 *
67 * Again, channels 5-7 transfer _physical_ words (16 bits), so addresses
68 * and counts _must_ be word-aligned (the lowest address bit is _ignored_ at
69 * the hardware level, so odd-byte transfers aren't possible).
70 *
71 * Transfer count (_not # bytes_) is limited to 64K, represented as actual
72 * count - 1 : 64K => 0xFFFF, 1 => 0x0000. Thus, count is always 1 or more,
73 * and up to 128K bytes may be transferred on channels 5-7 in one operation.
74 *
75 */
76
77 #ifndef CONFIG_GENERIC_ISA_DMA_SUPPORT_BROKEN
78 #define MAX_DMA_CHANNELS 8
79 #endif
80
81 /*
82 * The maximum address in KSEG0 that we can perform a DMA transfer to on this
83 * platform. This describes only the PC style part of the DMA logic like on
84 * Deskstations or Acer PICA but not the much more versatile DMA logic used
85 * for the local devices on Acer PICA or Magnums.
86 */
87 #if defined(CONFIG_SGI_IP22) || defined(CONFIG_SGI_IP28)
88 /* don't care; ISA bus master won't work, ISA slave DMA supports 32bit addr */
89 #define MAX_DMA_ADDRESS PAGE_OFFSET
90 #else
91 #define MAX_DMA_ADDRESS (PAGE_OFFSET + 0x01000000)
92 #endif
93 #define MAX_DMA_PFN PFN_DOWN(virt_to_phys((void *)MAX_DMA_ADDRESS))
94
95 #ifndef MAX_DMA32_PFN
96 #define MAX_DMA32_PFN (1UL << (32 - PAGE_SHIFT))
97 #endif
98
99 /* 8237 DMA controllers */
100 #define IO_DMA1_BASE 0x00 /* 8 bit slave DMA, channels 0..3 */
101 #define IO_DMA2_BASE 0xC0 /* 16 bit master DMA, ch 4(=slave input)..7 */
102
103 /* DMA controller registers */
104 #define DMA1_CMD_REG 0x08 /* command register (w) */
105 #define DMA1_STAT_REG 0x08 /* status register (r) */
106 #define DMA1_REQ_REG 0x09 /* request register (w) */
107 #define DMA1_MASK_REG 0x0A /* single-channel mask (w) */
108 #define DMA1_MODE_REG 0x0B /* mode register (w) */
109 #define DMA1_CLEAR_FF_REG 0x0C /* clear pointer flip-flop (w) */
110 #define DMA1_TEMP_REG 0x0D /* Temporary Register (r) */
111 #define DMA1_RESET_REG 0x0D /* Master Clear (w) */
112 #define DMA1_CLR_MASK_REG 0x0E /* Clear Mask */
113 #define DMA1_MASK_ALL_REG 0x0F /* all-channels mask (w) */
114
115 #define DMA2_CMD_REG 0xD0 /* command register (w) */
116 #define DMA2_STAT_REG 0xD0 /* status register (r) */
117 #define DMA2_REQ_REG 0xD2 /* request register (w) */
118 #define DMA2_MASK_REG 0xD4 /* single-channel mask (w) */
119 #define DMA2_MODE_REG 0xD6 /* mode register (w) */
120 #define DMA2_CLEAR_FF_REG 0xD8 /* clear pointer flip-flop (w) */
121 #define DMA2_TEMP_REG 0xDA /* Temporary Register (r) */
122 #define DMA2_RESET_REG 0xDA /* Master Clear (w) */
123 #define DMA2_CLR_MASK_REG 0xDC /* Clear Mask */
124 #define DMA2_MASK_ALL_REG 0xDE /* all-channels mask (w) */
125
126 #define DMA_ADDR_0 0x00 /* DMA address registers */
127 #define DMA_ADDR_1 0x02
128 #define DMA_ADDR_2 0x04
129 #define DMA_ADDR_3 0x06
130 #define DMA_ADDR_4 0xC0
131 #define DMA_ADDR_5 0xC4
132 #define DMA_ADDR_6 0xC8
133 #define DMA_ADDR_7 0xCC
134
135 #define DMA_CNT_0 0x01 /* DMA count registers */
136 #define DMA_CNT_1 0x03
137 #define DMA_CNT_2 0x05
138 #define DMA_CNT_3 0x07
139 #define DMA_CNT_4 0xC2
140 #define DMA_CNT_5 0xC6
141 #define DMA_CNT_6 0xCA
142 #define DMA_CNT_7 0xCE
143
144 #define DMA_PAGE_0 0x87 /* DMA page registers */
145 #define DMA_PAGE_1 0x83
146 #define DMA_PAGE_2 0x81
147 #define DMA_PAGE_3 0x82
148 #define DMA_PAGE_5 0x8B
149 #define DMA_PAGE_6 0x89
150 #define DMA_PAGE_7 0x8A
151
152 #define DMA_MODE_READ 0x44 /* I/O to memory, no autoinit, increment, single mode */
153 #define DMA_MODE_WRITE 0x48 /* memory to I/O, no autoinit, increment, single mode */
154 #define DMA_MODE_CASCADE 0xC0 /* pass thru DREQ->HRQ, DACK<-HLDA only */
155
156 #define DMA_AUTOINIT 0x10
157
158 extern spinlock_t dma_spin_lock;
159
160 static __inline__ unsigned long claim_dma_lock(void)
161 {
162 unsigned long flags;
163 spin_lock_irqsave(&dma_spin_lock, flags);
164 return flags;
165 }
166
167 static __inline__ void release_dma_lock(unsigned long flags)
168 {
169 spin_unlock_irqrestore(&dma_spin_lock, flags);
170 }
171
172 /* enable/disable a specific DMA channel */
173 static __inline__ void enable_dma(unsigned int dmanr)
174 {
175 if (dmanr<=3)
176 dma_outb(dmanr, DMA1_MASK_REG);
177 else
178 dma_outb(dmanr & 3, DMA2_MASK_REG);
179 }
180
181 static __inline__ void disable_dma(unsigned int dmanr)
182 {
183 if (dmanr<=3)
184 dma_outb(dmanr | 4, DMA1_MASK_REG);
185 else
186 dma_outb((dmanr & 3) | 4, DMA2_MASK_REG);
187 }
188
189 /* Clear the 'DMA Pointer Flip Flop'.
190 * Write 0 for LSB/MSB, 1 for MSB/LSB access.
191 * Use this once to initialize the FF to a known state.
192 * After that, keep track of it. :-)
193 * --- In order to do that, the DMA routines below should ---
194 * --- only be used while holding the DMA lock ! ---
195 */
196 static __inline__ void clear_dma_ff(unsigned int dmanr)
197 {
198 if (dmanr<=3)
199 dma_outb(0, DMA1_CLEAR_FF_REG);
200 else
201 dma_outb(0, DMA2_CLEAR_FF_REG);
202 }
203
204 /* set mode (above) for a specific DMA channel */
205 static __inline__ void set_dma_mode(unsigned int dmanr, char mode)
206 {
207 if (dmanr<=3)
208 dma_outb(mode | dmanr, DMA1_MODE_REG);
209 else
210 dma_outb(mode | (dmanr&3), DMA2_MODE_REG);
211 }
212
213 /* Set only the page register bits of the transfer address.
214 * This is used for successive transfers when we know the contents of
215 * the lower 16 bits of the DMA current address register, but a 64k boundary
216 * may have been crossed.
217 */
218 static __inline__ void set_dma_page(unsigned int dmanr, char pagenr)
219 {
220 switch(dmanr) {
221 case 0:
222 dma_outb(pagenr, DMA_PAGE_0);
223 break;
224 case 1:
225 dma_outb(pagenr, DMA_PAGE_1);
226 break;
227 case 2:
228 dma_outb(pagenr, DMA_PAGE_2);
229 break;
230 case 3:
231 dma_outb(pagenr, DMA_PAGE_3);
232 break;
233 case 5:
234 dma_outb(pagenr & 0xfe, DMA_PAGE_5);
235 break;
236 case 6:
237 dma_outb(pagenr & 0xfe, DMA_PAGE_6);
238 break;
239 case 7:
240 dma_outb(pagenr & 0xfe, DMA_PAGE_7);
241 break;
242 }
243 }
244
245
246 /* Set transfer address & page bits for specific DMA channel.
247 * Assumes dma flipflop is clear.
248 */
249 static __inline__ void set_dma_addr(unsigned int dmanr, unsigned int a)
250 {
251 set_dma_page(dmanr, a>>16);
252 if (dmanr <= 3) {
253 dma_outb( a & 0xff, ((dmanr&3)<<1) + IO_DMA1_BASE );
254 dma_outb( (a>>8) & 0xff, ((dmanr&3)<<1) + IO_DMA1_BASE );
255 } else {
256 dma_outb( (a>>1) & 0xff, ((dmanr&3)<<2) + IO_DMA2_BASE );
257 dma_outb( (a>>9) & 0xff, ((dmanr&3)<<2) + IO_DMA2_BASE );
258 }
259 }
260
261
262 /* Set transfer size (max 64k for DMA0..3, 128k for DMA5..7) for
263 * a specific DMA channel.
264 * You must ensure the parameters are valid.
265 * NOTE: from a manual: "the number of transfers is one more
266 * than the initial word count"! This is taken into account.
267 * Assumes dma flip-flop is clear.
268 * NOTE 2: "count" represents _bytes_ and must be even for channels 5-7.
269 */
270 static __inline__ void set_dma_count(unsigned int dmanr, unsigned int count)
271 {
272 count--;
273 if (dmanr <= 3) {
274 dma_outb( count & 0xff, ((dmanr&3)<<1) + 1 + IO_DMA1_BASE );
275 dma_outb( (count>>8) & 0xff, ((dmanr&3)<<1) + 1 + IO_DMA1_BASE );
276 } else {
277 dma_outb( (count>>1) & 0xff, ((dmanr&3)<<2) + 2 + IO_DMA2_BASE );
278 dma_outb( (count>>9) & 0xff, ((dmanr&3)<<2) + 2 + IO_DMA2_BASE );
279 }
280 }
281
282
283 /* Get DMA residue count. After a DMA transfer, this
284 * should return zero. Reading this while a DMA transfer is
285 * still in progress will return unpredictable results.
286 * If called before the channel has been used, it may return 1.
287 * Otherwise, it returns the number of _bytes_ left to transfer.
288 *
289 * Assumes DMA flip-flop is clear.
290 */
291 static __inline__ int get_dma_residue(unsigned int dmanr)
292 {
293 unsigned int io_port = (dmanr<=3)? ((dmanr&3)<<1) + 1 + IO_DMA1_BASE
294 : ((dmanr&3)<<2) + 2 + IO_DMA2_BASE;
295
296 /* using short to get 16-bit wrap around */
297 unsigned short count;
298
299 count = 1 + dma_inb(io_port);
300 count += dma_inb(io_port) << 8;
301
302 return (dmanr<=3)? count : (count<<1);
303 }
304
305
306 /* These are in kernel/dma.c: */
307 extern int request_dma(unsigned int dmanr, const char * device_id); /* reserve a DMA channel */
308 extern void free_dma(unsigned int dmanr); /* release it again */
309
310 #endif /* _ASM_DMA_H */
311
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