1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * spu_restore.c
4 *
5 * (C) Copyright IBM Corp. 2005
6 *
7 * SPU-side context restore sequence outlined in
8 * Synergistic Processor Element Book IV
9 *
10 * Author: Mark Nutter <mnutter@us.ibm.com>
11 */
12
13
14 #ifndef LS_SIZE
15 #define LS_SIZE 0x40000 /* 256K (in bytes) */
16 #endif
17
18 typedef unsigned int u32;
19 typedef unsigned long long u64;
20
21 #include <spu_intrinsics.h>
22 #include <asm/spu_csa.h>
23 #include "spu_utils.h"
24
25 #define BR_INSTR 0x327fff80 /* br -4 */
26 #define NOP_INSTR 0x40200000 /* nop */
27 #define HEQ_INSTR 0x7b000000 /* heq $0, $0 */
28 #define STOP_INSTR 0x00000000 /* stop 0x0 */
29 #define ILLEGAL_INSTR 0x00800000 /* illegal instr */
30 #define RESTORE_COMPLETE 0x00003ffc /* stop 0x3ffc */
31
32 static inline void fetch_regs_from_mem(addr64 lscsa_ea)
33 {
34 unsigned int ls = (unsigned int)®s_spill[0];
35 unsigned int size = sizeof(regs_spill);
36 unsigned int tag_id = 0;
37 unsigned int cmd = 0x40; /* GET */
38
39 spu_writech(MFC_LSA, ls);
40 spu_writech(MFC_EAH, lscsa_ea.ui[0]);
41 spu_writech(MFC_EAL, lscsa_ea.ui[1]);
42 spu_writech(MFC_Size, size);
43 spu_writech(MFC_TagID, tag_id);
44 spu_writech(MFC_Cmd, cmd);
45 }
46
47 static inline void restore_upper_240kb(addr64 lscsa_ea)
48 {
49 unsigned int ls = 16384;
50 unsigned int list = (unsigned int)&dma_list[0];
51 unsigned int size = sizeof(dma_list);
52 unsigned int tag_id = 0;
53 unsigned int cmd = 0x44; /* GETL */
54
55 /* Restore, Step 4:
56 * Enqueue the GETL command (tag 0) to the MFC SPU command
57 * queue to transfer the upper 240 kb of LS from CSA.
58 */
59 spu_writech(MFC_LSA, ls);
60 spu_writech(MFC_EAH, lscsa_ea.ui[0]);
61 spu_writech(MFC_EAL, list);
62 spu_writech(MFC_Size, size);
63 spu_writech(MFC_TagID, tag_id);
64 spu_writech(MFC_Cmd, cmd);
65 }
66
67 static inline void restore_decr(void)
68 {
69 unsigned int offset;
70 unsigned int decr_running;
71 unsigned int decr;
72
73 /* Restore, Step 6(moved):
74 * If the LSCSA "decrementer running" flag is set
75 * then write the SPU_WrDec channel with the
76 * decrementer value from LSCSA.
77 */
78 offset = LSCSA_QW_OFFSET(decr_status);
79 decr_running = regs_spill[offset].slot[0] & SPU_DECR_STATUS_RUNNING;
80 if (decr_running) {
81 offset = LSCSA_QW_OFFSET(decr);
82 decr = regs_spill[offset].slot[0];
83 spu_writech(SPU_WrDec, decr);
84 }
85 }
86
87 static inline void write_ppu_mb(void)
88 {
89 unsigned int offset;
90 unsigned int data;
91
92 /* Restore, Step 11:
93 * Write the MFC_WrOut_MB channel with the PPU_MB
94 * data from LSCSA.
95 */
96 offset = LSCSA_QW_OFFSET(ppu_mb);
97 data = regs_spill[offset].slot[0];
98 spu_writech(SPU_WrOutMbox, data);
99 }
100
101 static inline void write_ppuint_mb(void)
102 {
103 unsigned int offset;
104 unsigned int data;
105
106 /* Restore, Step 12:
107 * Write the MFC_WrInt_MB channel with the PPUINT_MB
108 * data from LSCSA.
109 */
110 offset = LSCSA_QW_OFFSET(ppuint_mb);
111 data = regs_spill[offset].slot[0];
112 spu_writech(SPU_WrOutIntrMbox, data);
113 }
114
115 static inline void restore_fpcr(void)
116 {
117 unsigned int offset;
118 vector unsigned int fpcr;
119
120 /* Restore, Step 13:
121 * Restore the floating-point status and control
122 * register from the LSCSA.
123 */
124 offset = LSCSA_QW_OFFSET(fpcr);
125 fpcr = regs_spill[offset].v;
126 spu_mtfpscr(fpcr);
127 }
128
129 static inline void restore_srr0(void)
130 {
131 unsigned int offset;
132 unsigned int srr0;
133
134 /* Restore, Step 14:
135 * Restore the SPU SRR0 data from the LSCSA.
136 */
137 offset = LSCSA_QW_OFFSET(srr0);
138 srr0 = regs_spill[offset].slot[0];
139 spu_writech(SPU_WrSRR0, srr0);
140 }
141
142 static inline void restore_event_mask(void)
143 {
144 unsigned int offset;
145 unsigned int event_mask;
146
147 /* Restore, Step 15:
148 * Restore the SPU_RdEventMsk data from the LSCSA.
149 */
150 offset = LSCSA_QW_OFFSET(event_mask);
151 event_mask = regs_spill[offset].slot[0];
152 spu_writech(SPU_WrEventMask, event_mask);
153 }
154
155 static inline void restore_tag_mask(void)
156 {
157 unsigned int offset;
158 unsigned int tag_mask;
159
160 /* Restore, Step 16:
161 * Restore the SPU_RdTagMsk data from the LSCSA.
162 */
163 offset = LSCSA_QW_OFFSET(tag_mask);
164 tag_mask = regs_spill[offset].slot[0];
165 spu_writech(MFC_WrTagMask, tag_mask);
166 }
167
168 static inline void restore_complete(void)
169 {
170 extern void exit_fini(void);
171 unsigned int *exit_instrs = (unsigned int *)exit_fini;
172 unsigned int offset;
173 unsigned int stopped_status;
174 unsigned int stopped_code;
175
176 /* Restore, Step 18:
177 * Issue a stop-and-signal instruction with
178 * "good context restore" signal value.
179 *
180 * Restore, Step 19:
181 * There may be additional instructions placed
182 * here by the PPE Sequence for SPU Context
183 * Restore in order to restore the correct
184 * "stopped state".
185 *
186 * This step is handled here by analyzing the
187 * LSCSA.stopped_status and then modifying the
188 * exit() function to behave appropriately.
189 */
190
191 offset = LSCSA_QW_OFFSET(stopped_status);
192 stopped_status = regs_spill[offset].slot[0];
193 stopped_code = regs_spill[offset].slot[1];
194
195 switch (stopped_status) {
196 case SPU_STOPPED_STATUS_P_I:
197 /* SPU_Status[P,I]=1. Add illegal instruction
198 * followed by stop-and-signal instruction after
199 * end of restore code.
200 */
201 exit_instrs[0] = RESTORE_COMPLETE;
202 exit_instrs[1] = ILLEGAL_INSTR;
203 exit_instrs[2] = STOP_INSTR | stopped_code;
204 break;
205 case SPU_STOPPED_STATUS_P_H:
206 /* SPU_Status[P,H]=1. Add 'heq $0, $0' followed
207 * by stop-and-signal instruction after end of
208 * restore code.
209 */
210 exit_instrs[0] = RESTORE_COMPLETE;
211 exit_instrs[1] = HEQ_INSTR;
212 exit_instrs[2] = STOP_INSTR | stopped_code;
213 break;
214 case SPU_STOPPED_STATUS_S_P:
215 /* SPU_Status[S,P]=1. Add nop instruction
216 * followed by 'br -4' after end of restore
217 * code.
218 */
219 exit_instrs[0] = RESTORE_COMPLETE;
220 exit_instrs[1] = STOP_INSTR | stopped_code;
221 exit_instrs[2] = NOP_INSTR;
222 exit_instrs[3] = BR_INSTR;
223 break;
224 case SPU_STOPPED_STATUS_S_I:
225 /* SPU_Status[S,I]=1. Add illegal instruction
226 * followed by 'br -4' after end of restore code.
227 */
228 exit_instrs[0] = RESTORE_COMPLETE;
229 exit_instrs[1] = ILLEGAL_INSTR;
230 exit_instrs[2] = NOP_INSTR;
231 exit_instrs[3] = BR_INSTR;
232 break;
233 case SPU_STOPPED_STATUS_I:
234 /* SPU_Status[I]=1. Add illegal instruction followed
235 * by infinite loop after end of restore sequence.
236 */
237 exit_instrs[0] = RESTORE_COMPLETE;
238 exit_instrs[1] = ILLEGAL_INSTR;
239 exit_instrs[2] = NOP_INSTR;
240 exit_instrs[3] = BR_INSTR;
241 break;
242 case SPU_STOPPED_STATUS_S:
243 /* SPU_Status[S]=1. Add two 'nop' instructions. */
244 exit_instrs[0] = RESTORE_COMPLETE;
245 exit_instrs[1] = NOP_INSTR;
246 exit_instrs[2] = NOP_INSTR;
247 exit_instrs[3] = BR_INSTR;
248 break;
249 case SPU_STOPPED_STATUS_H:
250 /* SPU_Status[H]=1. Add 'heq $0, $0' instruction
251 * after end of restore code.
252 */
253 exit_instrs[0] = RESTORE_COMPLETE;
254 exit_instrs[1] = HEQ_INSTR;
255 exit_instrs[2] = NOP_INSTR;
256 exit_instrs[3] = BR_INSTR;
257 break;
258 case SPU_STOPPED_STATUS_P:
259 /* SPU_Status[P]=1. Add stop-and-signal instruction
260 * after end of restore code.
261 */
262 exit_instrs[0] = RESTORE_COMPLETE;
263 exit_instrs[1] = STOP_INSTR | stopped_code;
264 break;
265 case SPU_STOPPED_STATUS_R:
266 /* SPU_Status[I,S,H,P,R]=0. Add infinite loop. */
267 exit_instrs[0] = RESTORE_COMPLETE;
268 exit_instrs[1] = NOP_INSTR;
269 exit_instrs[2] = NOP_INSTR;
270 exit_instrs[3] = BR_INSTR;
271 break;
272 default:
273 /* SPU_Status[R]=1. No additional instructions. */
274 break;
275 }
276 spu_sync();
277 }
278
279 /**
280 * main - entry point for SPU-side context restore.
281 *
282 * This code deviates from the documented sequence in the
283 * following aspects:
284 *
285 * 1. The EA for LSCSA is passed from PPE in the
286 * signal notification channels.
287 * 2. The register spill area is pulled by SPU
288 * into LS, rather than pushed by PPE.
289 * 3. All 128 registers are restored by exit().
290 * 4. The exit() function is modified at run
291 * time in order to properly restore the
292 * SPU_Status register.
293 */
294 int main()
295 {
296 addr64 lscsa_ea;
297
298 lscsa_ea.ui[0] = spu_readch(SPU_RdSigNotify1);
299 lscsa_ea.ui[1] = spu_readch(SPU_RdSigNotify2);
300 fetch_regs_from_mem(lscsa_ea);
301
302 set_event_mask(); /* Step 1. */
303 set_tag_mask(); /* Step 2. */
304 build_dma_list(lscsa_ea); /* Step 3. */
305 restore_upper_240kb(lscsa_ea); /* Step 4. */
306 /* Step 5: done by 'exit'. */
307 enqueue_putllc(lscsa_ea); /* Step 7. */
308 set_tag_update(); /* Step 8. */
309 read_tag_status(); /* Step 9. */
310 restore_decr(); /* moved Step 6. */
311 read_llar_status(); /* Step 10. */
312 write_ppu_mb(); /* Step 11. */
313 write_ppuint_mb(); /* Step 12. */
314 restore_fpcr(); /* Step 13. */
315 restore_srr0(); /* Step 14. */
316 restore_event_mask(); /* Step 15. */
317 restore_tag_mask(); /* Step 16. */
318 /* Step 17. done by 'exit'. */
319 restore_complete(); /* Step 18. */
320
321 return 0;
322 }
323
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