linux/arch/loongarch/include/asm/fpu.h

/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Author: Huacai Chen <chenhuacai@loongson.cn>
 * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
 */
#ifndef _ASM_FPU_H
#define _ASM_FPU_H

#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/ptrace.h>
#include <linux/thread_info.h>
#include <linux/bitops.h>

#include <asm/cpu.h>
#include <asm/cpu-features.h>
#include <asm/current.h>
#include <asm/loongarch.h>
#include <asm/processor.h>
#include <asm/ptrace.h>

struct sigcontext;

extern void kernel_fpu_begin(void);
extern void kernel_fpu_end(void);

extern void _init_fpu(unsigned int);
extern void _save_fp(struct loongarch_fpu *);
extern void _restore_fp(struct loongarch_fpu *);

extern void _save_lsx(struct loongarch_fpu *fpu);
extern void _restore_lsx(struct loongarch_fpu *fpu);
extern void _init_lsx_upper(void);
extern void _restore_lsx_upper(struct loongarch_fpu *fpu);

extern void _save_lasx(struct loongarch_fpu *fpu);
extern void _restore_lasx(struct loongarch_fpu *fpu);
extern void _init_lasx_upper(void);
extern void _restore_lasx_upper(struct loongarch_fpu *fpu);

static inline void enable_lsx(void);
static inline void disable_lsx(void);
static inline void save_lsx(struct task_struct *t);
static inline void restore_lsx(struct task_struct *t);

static inline void enable_lasx(void);
static inline void disable_lasx(void);
static inline void save_lasx(struct task_struct *t);
static inline void restore_lasx(struct task_struct *t);

/*
 * Mask the FCSR Cause bits according to the Enable bits, observing
 * that Unimplemented is always enabled.
 */
static inline unsigned long mask_fcsr_x(unsigned long fcsr)
{
	return fcsr & ((fcsr & FPU_CSR_ALL_E) <<
			(ffs(FPU_CSR_ALL_X) - ffs(FPU_CSR_ALL_E)));
}

static inline int is_fp_enabled(void)
{
	return (csr_read32(LOONGARCH_CSR_EUEN) & CSR_EUEN_FPEN) ?
		1 : 0;
}

static inline int is_lsx_enabled(void)
{
	if (!cpu_has_lsx)
		return 0;

	return (csr_read32(LOONGARCH_CSR_EUEN) & CSR_EUEN_LSXEN) ?
		1 : 0;
}

static inline int is_lasx_enabled(void)
{
	if (!cpu_has_lasx)
		return 0;

	return (csr_read32(LOONGARCH_CSR_EUEN) & CSR_EUEN_LASXEN) ?
		1 : 0;
}

static inline int is_simd_enabled(void)
{
	return is_lsx_enabled() | is_lasx_enabled();
}

#define enable_fpu()		set_csr_euen(CSR_EUEN_FPEN)

#define disable_fpu()		clear_csr_euen(CSR_EUEN_FPEN)

#define clear_fpu_owner()	clear_thread_flag(TIF_USEDFPU)

static inline int is_fpu_owner(void)
{
	return test_thread_flag(TIF_USEDFPU);
}

static inline void __own_fpu(void)
{
	enable_fpu();
	set_thread_flag(TIF_USEDFPU);
	KSTK_EUEN(current) |= CSR_EUEN_FPEN;
}

static inline void own_fpu_inatomic(int restore)
{
	if (cpu_has_fpu && !is_fpu_owner()) {
		__own_fpu();
		if (restore)
			_restore_fp(&current->thread.fpu);
	}
}

static inline void own_fpu(int restore)
{
	preempt_disable();
	own_fpu_inatomic(restore);
	preempt_enable();
}

static inline void lose_fpu_inatomic(int save, struct task_struct *tsk)
{
	if (is_fpu_owner()) {
		if (!is_simd_enabled()) {
			if (save)
				_save_fp(&tsk->thread.fpu);
			disable_fpu();
		} else {
			if (save) {
				if (!is_lasx_enabled())
					save_lsx(tsk);
				else
					save_lasx(tsk);
			}
			disable_fpu();
			disable_lsx();
			disable_lasx();
			clear_tsk_thread_flag(tsk, TIF_USEDSIMD);
		}
		clear_tsk_thread_flag(tsk, TIF_USEDFPU);
	}
	KSTK_EUEN(tsk) &= ~(CSR_EUEN_FPEN | CSR_EUEN_LSXEN | CSR_EUEN_LASXEN);
}

static inline void lose_fpu(int save)
{
	preempt_disable();
	lose_fpu_inatomic(save, current);
	preempt_enable();
}

static inline void init_fpu(void)
{
	unsigned int fcsr = current->thread.fpu.fcsr;

	__own_fpu();
	_init_fpu(fcsr);
	set_used_math();
}

static inline void save_fp(struct task_struct *tsk)
{
	if (cpu_has_fpu)
		_save_fp(&tsk->thread.fpu);
}

static inline void restore_fp(struct task_struct *tsk)
{
	if (cpu_has_fpu)
		_restore_fp(&tsk->thread.fpu);
}

static inline union fpureg *get_fpu_regs(struct task_struct *tsk)
{
	if (tsk == current) {
		preempt_disable();
		if (is_fpu_owner())
			_save_fp(&current->thread.fpu);
		preempt_enable();
	}

	return tsk->thread.fpu.fpr;
}

static inline int is_simd_owner(void)
{
	return test_thread_flag(TIF_USEDSIMD);
}

#ifdef CONFIG_CPU_HAS_LSX

static inline void enable_lsx(void)
{
	if (cpu_has_lsx)
		csr_xchg32(CSR_EUEN_LSXEN, CSR_EUEN_LSXEN, LOONGARCH_CSR_EUEN);
}

static inline void disable_lsx(void)
{
	if (cpu_has_lsx)
		csr_xchg32(0, CSR_EUEN_LSXEN, LOONGARCH_CSR_EUEN);
}

static inline void save_lsx(struct task_struct *t)
{
	if (cpu_has_lsx)
		_save_lsx(&t->thread.fpu);
}

static inline void restore_lsx(struct task_struct *t)
{
	if (cpu_has_lsx)
		_restore_lsx(&t->thread.fpu);
}

static inline void init_lsx_upper(void)
{
	/*
	 * Check cpu_has_lsx only if it's a constant. This will allow the
	 * compiler to optimise out code for CPUs without LSX without adding
	 * an extra redundant check for CPUs with LSX.
	 */
	if (__builtin_constant_p(cpu_has_lsx) && !cpu_has_lsx)
		return;

	_init_lsx_upper();
}

static inline void restore_lsx_upper(struct task_struct *t)
{
	if (cpu_has_lsx)
		_restore_lsx_upper(&t->thread.fpu);
}

#else
static inline void enable_lsx(void) {}
static inline void disable_lsx(void) {}
static inline void save_lsx(struct task_struct *t) {}
static inline void restore_lsx(struct task_struct *t) {}
static inline void init_lsx_upper(void) {}
static inline void restore_lsx_upper(struct task_struct *t) {}
#endif

#ifdef CONFIG_CPU_HAS_LASX

static inline void enable_lasx(void)
{

	if (cpu_has_lasx)
		csr_xchg32(CSR_EUEN_LASXEN, CSR_EUEN_LASXEN, LOONGARCH_CSR_EUEN);
}

static inline void disable_lasx(void)
{
	if (cpu_has_lasx)
		csr_xchg32(0, CSR_EUEN_LASXEN, LOONGARCH_CSR_EUEN);
}

static inline void save_lasx(struct task_struct *t)
{
	if (cpu_has_lasx)
		_save_lasx(&t->thread.fpu);
}

static inline void restore_lasx(struct task_struct *t)
{
	if (cpu_has_lasx)
		_restore_lasx(&t->thread.fpu);
}

static inline void init_lasx_upper(void)
{
	if (cpu_has_lasx)
		_init_lasx_upper();
}

static inline void restore_lasx_upper(struct task_struct *t)
{
	if (cpu_has_lasx)
		_restore_lasx_upper(&t->thread.fpu);
}

#else
static inline void enable_lasx(void) {}
static inline void disable_lasx(void) {}
static inline void save_lasx(struct task_struct *t) {}
static inline void restore_lasx(struct task_struct *t) {}
static inline void init_lasx_upper(void) {}
static inline void restore_lasx_upper(struct task_struct *t) {}
#endif

static inline int thread_lsx_context_live(void)
{
	if (__builtin_constant_p(cpu_has_lsx) && !cpu_has_lsx)
		return 0;

	return test_thread_flag(TIF_LSX_CTX_LIVE);
}

static inline int thread_lasx_context_live(void)
{
	if (__builtin_constant_p(cpu_has_lasx) && !cpu_has_lasx)
		return 0;

	return test_thread_flag(TIF_LASX_CTX_LIVE);
}

#endif /* _ASM_FPU_H */