1 /*
2 * Copyright (C) 2002 MontaVista Software Inc.
3 * Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
4 *
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License as published by the
7 * Free Software Foundation; either version 2 of the License, or (at your
8 * option) any later version.
9 */
10 #ifndef _ASM_FPU_H
11 #define _ASM_FPU_H
12
13 #include <linux/sched.h>
14 #include <linux/thread_info.h>
15 #include <linux/bitops.h>
16
17 #include <asm/mipsregs.h>
18 #include <asm/cpu.h>
19 #include <asm/cpu-features.h>
20 #include <asm/fpu_emulator.h>
21 #include <asm/hazards.h>
22 #include <asm/processor.h>
23 #include <asm/current.h>
24 #include <asm/msa.h>
25
26 #ifdef CONFIG_MIPS_MT_FPAFF
27 #include <asm/mips_mt.h>
28 #endif
29
30 struct sigcontext;
31 struct sigcontext32;
32
33 extern void _init_fpu(unsigned int);
34 extern void _save_fp(struct task_struct *);
35 extern void _restore_fp(struct task_struct *);
36
37 /*
38 * This enum specifies a mode in which we want the FPU to operate, for cores
39 * which implement the Status.FR bit. Note that the bottom bit of the value
40 * purposefully matches the desired value of the Status.FR bit.
41 */
42 enum fpu_mode {
43 FPU_32BIT = 0, /* FR = 0 */
44 FPU_64BIT, /* FR = 1, FRE = 0 */
45 FPU_AS_IS,
46 FPU_HYBRID, /* FR = 1, FRE = 1 */
47
48 #define FPU_FR_MASK 0x1
49 };
50
51 #define __disable_fpu() \
52 do { \
53 clear_c0_status(ST0_CU1); \
54 disable_fpu_hazard(); \
55 } while (0)
56
__enable_fpu(enum fpu_mode mode)57 static inline int __enable_fpu(enum fpu_mode mode)
58 {
59 int fr;
60
61 switch (mode) {
62 case FPU_AS_IS:
63 /* just enable the FPU in its current mode */
64 set_c0_status(ST0_CU1);
65 enable_fpu_hazard();
66 return 0;
67
68 case FPU_HYBRID:
69 if (!cpu_has_fre)
70 return SIGFPE;
71
72 /* set FRE */
73 set_c0_config5(MIPS_CONF5_FRE);
74 goto fr_common;
75
76 case FPU_64BIT:
77 #if !(defined(CONFIG_CPU_MIPSR2) || defined(CONFIG_CPU_MIPSR6) \
78 || defined(CONFIG_64BIT))
79 /* we only have a 32-bit FPU */
80 return SIGFPE;
81 #endif
82 /* fall through */
83 case FPU_32BIT:
84 if (cpu_has_fre) {
85 /* clear FRE */
86 clear_c0_config5(MIPS_CONF5_FRE);
87 }
88 fr_common:
89 /* set CU1 & change FR appropriately */
90 fr = (int)mode & FPU_FR_MASK;
91 change_c0_status(ST0_CU1 | ST0_FR, ST0_CU1 | (fr ? ST0_FR : 0));
92 enable_fpu_hazard();
93
94 /* check FR has the desired value */
95 if (!!(read_c0_status() & ST0_FR) == !!fr)
96 return 0;
97
98 /* unsupported FR value */
99 __disable_fpu();
100 return SIGFPE;
101
102 default:
103 BUG();
104 }
105
106 return SIGFPE;
107 }
108
109 #define clear_fpu_owner() clear_thread_flag(TIF_USEDFPU)
110
__is_fpu_owner(void)111 static inline int __is_fpu_owner(void)
112 {
113 return test_thread_flag(TIF_USEDFPU);
114 }
115
is_fpu_owner(void)116 static inline int is_fpu_owner(void)
117 {
118 return cpu_has_fpu && __is_fpu_owner();
119 }
120
__own_fpu(void)121 static inline int __own_fpu(void)
122 {
123 enum fpu_mode mode;
124 int ret;
125
126 if (test_thread_flag(TIF_HYBRID_FPREGS))
127 mode = FPU_HYBRID;
128 else
129 mode = !test_thread_flag(TIF_32BIT_FPREGS);
130
131 ret = __enable_fpu(mode);
132 if (ret)
133 return ret;
134
135 KSTK_STATUS(current) |= ST0_CU1;
136 if (mode == FPU_64BIT || mode == FPU_HYBRID)
137 KSTK_STATUS(current) |= ST0_FR;
138 else /* mode == FPU_32BIT */
139 KSTK_STATUS(current) &= ~ST0_FR;
140
141 set_thread_flag(TIF_USEDFPU);
142 return 0;
143 }
144
own_fpu_inatomic(int restore)145 static inline int own_fpu_inatomic(int restore)
146 {
147 int ret = 0;
148
149 if (cpu_has_fpu && !__is_fpu_owner()) {
150 ret = __own_fpu();
151 if (restore && !ret)
152 _restore_fp(current);
153 }
154 return ret;
155 }
156
own_fpu(int restore)157 static inline int own_fpu(int restore)
158 {
159 int ret;
160
161 preempt_disable();
162 ret = own_fpu_inatomic(restore);
163 preempt_enable();
164 return ret;
165 }
166
lose_fpu(int save)167 static inline void lose_fpu(int save)
168 {
169 preempt_disable();
170 if (is_msa_enabled()) {
171 if (save) {
172 save_msa(current);
173 current->thread.fpu.fcr31 =
174 read_32bit_cp1_register(CP1_STATUS);
175 }
176 disable_msa();
177 clear_thread_flag(TIF_USEDMSA);
178 __disable_fpu();
179 } else if (is_fpu_owner()) {
180 if (save)
181 _save_fp(current);
182 __disable_fpu();
183 }
184 KSTK_STATUS(current) &= ~ST0_CU1;
185 clear_thread_flag(TIF_USEDFPU);
186 preempt_enable();
187 }
188
init_fpu(void)189 static inline int init_fpu(void)
190 {
191 unsigned int fcr31 = current->thread.fpu.fcr31;
192 int ret = 0;
193
194 if (cpu_has_fpu) {
195 unsigned int config5;
196
197 ret = __own_fpu();
198 if (ret)
199 return ret;
200
201 if (!cpu_has_fre) {
202 _init_fpu(fcr31);
203
204 return 0;
205 }
206
207 /*
208 * Ensure FRE is clear whilst running _init_fpu, since
209 * single precision FP instructions are used. If FRE
210 * was set then we'll just end up initialising all 32
211 * 64b registers.
212 */
213 config5 = clear_c0_config5(MIPS_CONF5_FRE);
214 enable_fpu_hazard();
215
216 _init_fpu(fcr31);
217
218 /* Restore FRE */
219 write_c0_config5(config5);
220 enable_fpu_hazard();
221 } else
222 fpu_emulator_init_fpu();
223
224 return ret;
225 }
226
save_fp(struct task_struct * tsk)227 static inline void save_fp(struct task_struct *tsk)
228 {
229 if (cpu_has_fpu)
230 _save_fp(tsk);
231 }
232
restore_fp(struct task_struct * tsk)233 static inline void restore_fp(struct task_struct *tsk)
234 {
235 if (cpu_has_fpu)
236 _restore_fp(tsk);
237 }
238
get_fpu_regs(struct task_struct * tsk)239 static inline union fpureg *get_fpu_regs(struct task_struct *tsk)
240 {
241 if (tsk == current) {
242 preempt_disable();
243 if (is_fpu_owner())
244 _save_fp(current);
245 preempt_enable();
246 }
247
248 return tsk->thread.fpu.fpr;
249 }
250
251 #endif /* _ASM_FPU_H */
252