/arch/powerpc/platforms/cell/spufs/spu_restore.c

  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
 18typedef unsigned int u32;
 19typedef 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
 32static inline void fetch_regs_from_mem(addr64 lscsa_ea)
 33{
 34	unsigned int ls = (unsigned int)&regs_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
 47static 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
 67static 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
 87static 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
101static 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
115static 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
129static 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
142static 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
155static 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
168static 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 */
294int 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}