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1/*
2 * arch/mips/dec/int-handler.S
3 *
4 * Copyright (C) 1995, 1996, 1997 Paul M. Antoine and Harald Koerfgen
5 * Copyright (C) 2000, 2001, 2002, 2003 Maciej W. Rozycki
6 *
7 * Written by Ralf Baechle and Andreas Busse, modified for DECStation
8 * support by Paul Antoine and Harald Koerfgen.
9 *
10 * completly rewritten:
11 * Copyright (C) 1998 Harald Koerfgen
12 *
13 * Rewritten extensively for controller-driven IRQ support
14 * by Maciej W. Rozycki.
15 */
16#include <linux/config.h>
17#include <asm/asm.h>
18#include <asm/regdef.h>
19#include <asm/mipsregs.h>
20#include <asm/stackframe.h>
21#include <asm/addrspace.h>
22
23#include <asm/dec/interrupts.h>
24#include <asm/dec/ioasic_addrs.h>
25#include <asm/dec/ioasic_ints.h>
26#include <asm/dec/kn01.h>
27#include <asm/dec/kn02.h>
28#include <asm/dec/kn02xa.h>
29#include <asm/dec/kn03.h>
30
31
32 .text
33 .set noreorder
34/*
35 * decstation_handle_int: Interrupt handler for DECStations
36 *
37 * We follow the model in the Indy interrupt code by David Miller, where he
38 * says: a lot of complication here is taken away because:
39 *
40 * 1) We handle one interrupt and return, sitting in a loop
41 * and moving across all the pending IRQ bits in the cause
42 * register is _NOT_ the answer, the common case is one
43 * pending IRQ so optimize in that direction.
44 *
45 * 2) We need not check against bits in the status register
46 * IRQ mask, that would make this routine slow as hell.
47 *
48 * 3) Linux only thinks in terms of all IRQs on or all IRQs
49 * off, nothing in between like BSD spl() brain-damage.
50 *
51 * Furthermore, the IRQs on the DECStations look basically (barring
52 * software IRQs which we don't use at all) like...
53 *
54 * DS2100/3100's, aka kn01, aka Pmax:
55 *
56 * MIPS IRQ Source
57 * -------- ------
58 * 0 Software (ignored)
59 * 1 Software (ignored)
60 * 2 SCSI
61 * 3 Lance Ethernet
62 * 4 DZ11 serial
63 * 5 RTC
64 * 6 Memory Controller
65 * 7 FPU
66 *
67 * DS5000/200, aka kn02, aka 3max:
68 *
69 * MIPS IRQ Source
70 * -------- ------
71 * 0 Software (ignored)
72 * 1 Software (ignored)
73 * 2 TurboChannel
74 * 3 RTC
75 * 4 Reserved
76 * 5 Memory Controller
77 * 6 Reserved
78 * 7 FPU
79 *
80 * DS5000/1xx's, aka kn02ba, aka 3min:
81 *
82 * MIPS IRQ Source
83 * -------- ------
84 * 0 Software (ignored)
85 * 1 Software (ignored)
86 * 2 TurboChannel Slot 0
87 * 3 TurboChannel Slot 1
88 * 4 TurboChannel Slot 2
89 * 5 TurboChannel Slot 3 (ASIC)
90 * 6 Halt button
91 * 7 FPU/R4k timer
92 *
93 * DS5000/2x's, aka kn02ca, aka maxine:
94 *
95 * MIPS IRQ Source
96 * -------- ------
97 * 0 Software (ignored)
98 * 1 Software (ignored)
99 * 2 Periodic Interrupt (100usec)
100 * 3 RTC
101 * 4 I/O write timeout
102 * 5 TurboChannel (ASIC)
103 * 6 Halt Keycode from Access.Bus keyboard (CTRL-ALT-ENTER)
104 * 7 FPU/R4k timer
105 *
106 * DS5000/2xx's, aka kn03, aka 3maxplus:
107 *
108 * MIPS IRQ Source
109 * -------- ------
110 * 0 Software (ignored)
111 * 1 Software (ignored)
112 * 2 System Board (ASIC)
113 * 3 RTC
114 * 4 Reserved
115 * 5 Memory
116 * 6 Halt Button
117 * 7 FPU/R4k timer
118 *
119 * We handle the IRQ according to _our_ priority (see setup.c),
120 * then we just return. If multiple IRQs are pending then we will
121 * just take another exception, big deal.
122 */
123 .align 5
124 NESTED(decstation_handle_int, PT_SIZE, ra)
125 .set noat
126 SAVE_ALL
127 CLI # TEST: interrupts should be off
128 .set at
129 .set noreorder
130
131 /*
132 * Get pending Interrupts
133 */
134 mfc0 t0,CP0_CAUSE # get pending interrupts
135 mfc0 t1,CP0_STATUS
136#ifdef CONFIG_MIPS32
137 lw t2,cpu_fpu_mask
138#endif
139 andi t0,ST0_IM # CAUSE.CE may be non-zero!
140 and t0,t1 # isolate allowed ones
141
142 beqz t0,spurious
143
144#ifdef CONFIG_MIPS32
145 and t2,t0
146 bnez t2,fpu # handle FPU immediately
147#endif
148
149 /*
150 * Find irq with highest priority
151 */
152 PTR_LA t1,cpu_mask_nr_tbl
1531: lw t2,(t1)
154 nop
155 and t2,t0
156 beqz t2,1b
157 addu t1,2*PTRSIZE # delay slot
158
159 /*
160 * Do the low-level stuff
161 */
162 lw a0,(-PTRSIZE)(t1)
163 nop
164 bgez a0,handle_it # irq_nr >= 0?
165 # irq_nr < 0: it is an address
166 nop
167 jr a0
168 # a trick to save a branch:
169 lui t2,(KN03_IOASIC_BASE>>16)&0xffff
170 # upper part of IOASIC Address
171
172/*
173 * Handle "IRQ Controller" Interrupts
174 * Masked Interrupts are still visible and have to be masked "by hand".
175 */
176 FEXPORT(kn02_io_int) # 3max
177 lui t0,(KN02_CSR_BASE>>16)&0xffff
178 # get interrupt status and mask
179 lw t0,(t0)
180 nop
181 andi t1,t0,KN02_IRQ_ALL
182 b 1f
183 srl t0,16 # shift interrupt mask
184
185 FEXPORT(kn02xa_io_int) # 3min/maxine
186 lui t2,(KN02XA_IOASIC_BASE>>16)&0xffff
187 # upper part of IOASIC Address
188
189 FEXPORT(kn03_io_int) # 3max+ (t2 loaded earlier)
190 lw t0,IO_REG_SIR(t2) # get status: IOASIC sir
191 lw t1,IO_REG_SIMR(t2) # get mask: IOASIC simr
192 nop
193
1941: and t0,t1 # mask out allowed ones
195
196 beqz t0,spurious
197
198 /*
199 * Find irq with highest priority
200 */
201 PTR_LA t1,asic_mask_nr_tbl
2022: lw t2,(t1)
203 nop
204 and t2,t0
205 beq zero,t2,2b
206 addu t1,2*PTRSIZE # delay slot
207
208 /*
209 * Do the low-level stuff
210 */
211 lw a0,%lo(-PTRSIZE)(t1)
212 nop
213 bgez a0,handle_it # irq_nr >= 0?
214 # irq_nr < 0: it is an address
215 nop
216 jr a0
217 nop # delay slot
218
219/*
220 * Dispatch low-priority interrupts. We reconsider all status
221 * bits again, which looks like a lose, but it makes the code
222 * simple and O(log n), so it gets compensated.
223 */
224 FEXPORT(cpu_all_int) # HALT, timers, software junk
225 li a0,DEC_CPU_IRQ_BASE
226 srl t0,CAUSEB_IP
227 li t1,CAUSEF_IP>>CAUSEB_IP # mask
228 b 1f
229 li t2,4 # nr of bits / 2
230
231 FEXPORT(kn02_all_int) # impossible ?
232 li a0,KN02_IRQ_BASE
233 li t1,KN02_IRQ_ALL # mask
234 b 1f
235 li t2,4 # nr of bits / 2
236
237 FEXPORT(asic_all_int) # various I/O ASIC junk
238 li a0,IO_IRQ_BASE
239 li t1,IO_IRQ_ALL # mask
240 b 1f
241 li t2,8 # nr of bits / 2
242
243/*
244 * Dispatch DMA interrupts -- O(log n).
245 */
246 FEXPORT(asic_dma_int) # I/O ASIC DMA events
247 li a0,IO_IRQ_BASE+IO_INR_DMA
248 srl t0,IO_INR_DMA
249 li t1,IO_IRQ_DMA>>IO_INR_DMA # mask
250 li t2,8 # nr of bits / 2
251
252 /*
253 * Find irq with highest priority.
254 * Highest irq number takes precedence.
255 */
2561: srlv t3,t1,t2
2572: xor t1,t3
258 and t3,t0,t1
259 beqz t3,3f
260 nop
261 move t0,t3
262 addu a0,t2
2633: srl t2,1
264 bnez t2,2b
265 srlv t3,t1,t2
266
267handle_it:
268 jal do_IRQ
269 move a1,sp
270
271 j ret_from_irq
272 nop
273
274#ifdef CONFIG_MIPS32
275fpu:
276 j handle_fpe_int
277 nop
278#endif
279
280spurious:
281 j spurious_interrupt
282 nop
283 END(decstation_handle_int)
284
285/*
286 * Generic unimplemented interrupt routines -- cpu_mask_nr_tbl
287 * and asic_mask_nr_tbl are initialized to point all interrupts here.
288 * The tables are then filled in by machine-specific initialisation
289 * in dec_setup().
290 */
291 FEXPORT(dec_intr_unimplemented)
292 move a1,t0 # cheats way of printing an arg!
293 PANIC("Unimplemented cpu interrupt! CP0_CAUSE: 0x%08x");
294
295 FEXPORT(asic_intr_unimplemented)
296 move a1,t0 # cheats way of printing an arg!
297 PANIC("Unimplemented asic interrupt! ASIC ISR: 0x%08x");
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