summaryrefslogtreecommitdiffstats
path: root/arch/xtensa/kernel/coprocessor.S
blob: 45cc0ae0af6f966ed778253b9624d46a783c2152 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
/*
 * arch/xtensa/kernel/coprocessor.S
 *
 * Xtensa processor configuration-specific table of coprocessor and
 * other custom register layout information.
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2003 - 2007 Tensilica Inc.
 */


#include <linux/linkage.h>
#include <asm/asm-offsets.h>
#include <asm/asmmacro.h>
#include <asm/coprocessor.h>
#include <asm/current.h>
#include <asm/regs.h>

#if XTENSA_HAVE_COPROCESSORS

/*
 * Macros for lazy context switch. 
 */

#define SAVE_CP_REGS(x)							\
	.if XTENSA_HAVE_COPROCESSOR(x);					\
		.align 4;						\
	.Lsave_cp_regs_cp##x:						\
		xchal_cp##x##_store a2 a4 a5 a6 a7;			\
		jx	a0;						\
	.endif

#define SAVE_CP_REGS_TAB(x)						\
	.if XTENSA_HAVE_COPROCESSOR(x);					\
		.long .Lsave_cp_regs_cp##x;				\
	.else;								\
		.long 0;						\
	.endif;								\
	.long THREAD_XTREGS_CP##x


#define LOAD_CP_REGS(x)							\
	.if XTENSA_HAVE_COPROCESSOR(x);					\
		.align 4;						\
	.Lload_cp_regs_cp##x:						\
		xchal_cp##x##_load a2 a4 a5 a6 a7;			\
		jx	a0;						\
	.endif

#define LOAD_CP_REGS_TAB(x)						\
	.if XTENSA_HAVE_COPROCESSOR(x);					\
		.long .Lload_cp_regs_cp##x;				\
	.else;								\
		.long 0;						\
	.endif;								\
	.long THREAD_XTREGS_CP##x

	__XTENSA_HANDLER

	SAVE_CP_REGS(0)
	SAVE_CP_REGS(1)
	SAVE_CP_REGS(2)
	SAVE_CP_REGS(3)
	SAVE_CP_REGS(4)
	SAVE_CP_REGS(5)
	SAVE_CP_REGS(6)
	SAVE_CP_REGS(7)

	LOAD_CP_REGS(0)
	LOAD_CP_REGS(1)
	LOAD_CP_REGS(2)
	LOAD_CP_REGS(3)
	LOAD_CP_REGS(4)
	LOAD_CP_REGS(5)
	LOAD_CP_REGS(6)
	LOAD_CP_REGS(7)

	.align 4
.Lsave_cp_regs_jump_table:
	SAVE_CP_REGS_TAB(0)
	SAVE_CP_REGS_TAB(1)
	SAVE_CP_REGS_TAB(2)
	SAVE_CP_REGS_TAB(3)
	SAVE_CP_REGS_TAB(4)
	SAVE_CP_REGS_TAB(5)
	SAVE_CP_REGS_TAB(6)
	SAVE_CP_REGS_TAB(7)

.Lload_cp_regs_jump_table:
	LOAD_CP_REGS_TAB(0)
	LOAD_CP_REGS_TAB(1)
	LOAD_CP_REGS_TAB(2)
	LOAD_CP_REGS_TAB(3)
	LOAD_CP_REGS_TAB(4)
	LOAD_CP_REGS_TAB(5)
	LOAD_CP_REGS_TAB(6)
	LOAD_CP_REGS_TAB(7)

/*
 * Entry condition:
 *
 *   a0:	trashed, original value saved on stack (PT_AREG0)
 *   a1:	a1
 *   a2:	new stack pointer, original in DEPC
 *   a3:	a3
 *   depc:	a2, original value saved on stack (PT_DEPC)
 *   excsave_1:	dispatch table
 *
 *   PT_DEPC >= VALID_DOUBLE_EXCEPTION_ADDRESS: double exception, DEPC
 *	     <  VALID_DOUBLE_EXCEPTION_ADDRESS: regular exception
 */

ENTRY(fast_coprocessor)

	/* Save remaining registers a1-a3 and SAR */

	s32i	a3, a2, PT_AREG3
	rsr	a3, sar
	s32i	a1, a2, PT_AREG1
	s32i	a3, a2, PT_SAR
	mov	a1, a2
	rsr	a2, depc
	s32i	a2, a1, PT_AREG2

	/*
	 * The hal macros require up to 4 temporary registers. We use a3..a6.
	 */

	s32i	a4, a1, PT_AREG4
	s32i	a5, a1, PT_AREG5
	s32i	a6, a1, PT_AREG6

	/* Find coprocessor number. Subtract first CP EXCCAUSE from EXCCAUSE */

	rsr	a3, exccause
	addi	a3, a3, -EXCCAUSE_COPROCESSOR0_DISABLED

	/* Set corresponding CPENABLE bit -> (sar:cp-index, a3: 1<<cp-index)*/

	ssl	a3			# SAR: 32 - coprocessor_number
	movi	a2, 1
	rsr	a0, cpenable
	sll	a2, a2
	or	a0, a0, a2
	wsr	a0, cpenable
	rsync

	/* Retrieve previous owner. (a3 still holds CP number) */

	movi	a0, coprocessor_owner	# list of owners
	addx4	a0, a3, a0		# entry for CP
	l32i	a4, a0, 0

	beqz	a4, 1f			# skip 'save' if no previous owner

	/* Disable coprocessor for previous owner. (a2 = 1 << CP number) */

	l32i	a5, a4, THREAD_CPENABLE
	xor	a5, a5, a2		# (1 << cp-id) still in a2
	s32i	a5, a4, THREAD_CPENABLE

	/*
	 * Get context save area and 'call' save routine. 
	 * (a4 still holds previous owner (thread_info), a3 CP number)
	 */

	movi	a5, .Lsave_cp_regs_jump_table
	movi	a0, 2f			# a0: 'return' address
	addx8	a3, a3, a5		# a3: coprocessor number
	l32i	a2, a3, 4		# a2: xtregs offset
	l32i	a3, a3, 0		# a3: jump address
	add	a2, a2, a4
	jx	a3

	/* Note that only a0 and a1 were preserved. */

2:	rsr	a3, exccause
	addi	a3, a3, -EXCCAUSE_COPROCESSOR0_DISABLED
	movi	a0, coprocessor_owner
	addx4	a0, a3, a0

	/* Set new 'owner' (a0 points to the CP owner, a3 contains the CP nr) */

1:	GET_THREAD_INFO (a4, a1)
	s32i	a4, a0, 0

	/* Get context save area and 'call' load routine. */

	movi	a5, .Lload_cp_regs_jump_table
	movi	a0, 1f
	addx8	a3, a3, a5
	l32i	a2, a3, 4		# a2: xtregs offset
	l32i	a3, a3, 0		# a3: jump address
	add	a2, a2, a4
	jx	a3

	/* Restore all registers and return from exception handler. */

1:	l32i	a6, a1, PT_AREG6
	l32i	a5, a1, PT_AREG5
	l32i	a4, a1, PT_AREG4

	l32i	a0, a1, PT_SAR
	l32i	a3, a1, PT_AREG3
	l32i	a2, a1, PT_AREG2
	wsr	a0, sar
	l32i	a0, a1, PT_AREG0
	l32i	a1, a1, PT_AREG1

	rfe

ENDPROC(fast_coprocessor)

	.text

/*
 * coprocessor_flush(struct thread_info*, index)
 *                             a2        a3
 *
 * Save coprocessor registers for coprocessor 'index'.
 * The register values are saved to or loaded from the coprocessor area
 * inside the task_info structure.
 *
 * Note that this function doesn't update the coprocessor_owner information!
 *
 */

ENTRY(coprocessor_flush)

	/* reserve 4 bytes on stack to save a0 */
	abi_entry(4)

	s32i	a0, a1, 0
	movi	a0, .Lsave_cp_regs_jump_table
	addx8	a3, a3, a0
	l32i	a4, a3, 4
	l32i	a3, a3, 0
	add	a2, a2, a4
	beqz	a3, 1f
	callx0	a3
1:	l32i	a0, a1, 0

	abi_ret(4)

ENDPROC(coprocessor_flush)

	.data

ENTRY(coprocessor_owner)

	.fill XCHAL_CP_MAX, 4, 0

END(coprocessor_owner)

#endif /* XTENSA_HAVE_COPROCESSORS */