1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * Author: Huacai Chen <chenhuacai@loongson.cn>
4  * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
5  */
6 #ifndef _ASM_FPU_H
7 #define _ASM_FPU_H
8 
9 #include <linux/sched.h>
10 #include <linux/sched/task_stack.h>
11 #include <linux/ptrace.h>
12 #include <linux/thread_info.h>
13 #include <linux/bitops.h>
14 
15 #include <asm/cpu.h>
16 #include <asm/cpu-features.h>
17 #include <asm/current.h>
18 #include <asm/loongarch.h>
19 #include <asm/processor.h>
20 #include <asm/ptrace.h>
21 
22 struct sigcontext;
23 
24 extern void _init_fpu(unsigned int);
25 extern void _save_fp(struct loongarch_fpu *);
26 extern void _restore_fp(struct loongarch_fpu *);
27 
28 /*
29  * Mask the FCSR Cause bits according to the Enable bits, observing
30  * that Unimplemented is always enabled.
31  */
mask_fcsr_x(unsigned long fcsr)32 static inline unsigned long mask_fcsr_x(unsigned long fcsr)
33 {
34 	return fcsr & ((fcsr & FPU_CSR_ALL_E) <<
35 			(ffs(FPU_CSR_ALL_X) - ffs(FPU_CSR_ALL_E)));
36 }
37 
is_fp_enabled(void)38 static inline int is_fp_enabled(void)
39 {
40 	return (csr_read32(LOONGARCH_CSR_EUEN) & CSR_EUEN_FPEN) ?
41 		1 : 0;
42 }
43 
44 #define enable_fpu()		set_csr_euen(CSR_EUEN_FPEN)
45 
46 #define disable_fpu()		clear_csr_euen(CSR_EUEN_FPEN)
47 
48 #define clear_fpu_owner()	clear_thread_flag(TIF_USEDFPU)
49 
is_fpu_owner(void)50 static inline int is_fpu_owner(void)
51 {
52 	return test_thread_flag(TIF_USEDFPU);
53 }
54 
__own_fpu(void)55 static inline void __own_fpu(void)
56 {
57 	enable_fpu();
58 	set_thread_flag(TIF_USEDFPU);
59 	KSTK_EUEN(current) |= CSR_EUEN_FPEN;
60 }
61 
own_fpu_inatomic(int restore)62 static inline void own_fpu_inatomic(int restore)
63 {
64 	if (cpu_has_fpu && !is_fpu_owner()) {
65 		__own_fpu();
66 		if (restore)
67 			_restore_fp(&current->thread.fpu);
68 	}
69 }
70 
own_fpu(int restore)71 static inline void own_fpu(int restore)
72 {
73 	preempt_disable();
74 	own_fpu_inatomic(restore);
75 	preempt_enable();
76 }
77 
lose_fpu_inatomic(int save,struct task_struct * tsk)78 static inline void lose_fpu_inatomic(int save, struct task_struct *tsk)
79 {
80 	if (is_fpu_owner()) {
81 		if (save)
82 			_save_fp(&tsk->thread.fpu);
83 		disable_fpu();
84 		clear_tsk_thread_flag(tsk, TIF_USEDFPU);
85 	}
86 	KSTK_EUEN(tsk) &= ~(CSR_EUEN_FPEN | CSR_EUEN_LSXEN | CSR_EUEN_LASXEN);
87 }
88 
lose_fpu(int save)89 static inline void lose_fpu(int save)
90 {
91 	preempt_disable();
92 	lose_fpu_inatomic(save, current);
93 	preempt_enable();
94 }
95 
init_fpu(void)96 static inline void init_fpu(void)
97 {
98 	unsigned int fcsr = current->thread.fpu.fcsr;
99 
100 	__own_fpu();
101 	_init_fpu(fcsr);
102 	set_used_math();
103 }
104 
save_fp(struct task_struct * tsk)105 static inline void save_fp(struct task_struct *tsk)
106 {
107 	if (cpu_has_fpu)
108 		_save_fp(&tsk->thread.fpu);
109 }
110 
restore_fp(struct task_struct * tsk)111 static inline void restore_fp(struct task_struct *tsk)
112 {
113 	if (cpu_has_fpu)
114 		_restore_fp(&tsk->thread.fpu);
115 }
116 
get_fpu_regs(struct task_struct * tsk)117 static inline union fpureg *get_fpu_regs(struct task_struct *tsk)
118 {
119 	if (tsk == current) {
120 		preempt_disable();
121 		if (is_fpu_owner())
122 			_save_fp(&current->thread.fpu);
123 		preempt_enable();
124 	}
125 
126 	return tsk->thread.fpu.fpr;
127 }
128 
129 #endif /* _ASM_FPU_H */
130