/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_PVCLOCK_H
#define _ASM_X86_PVCLOCK_H

#include <asm/barrier.h>
#include <asm/pvclock-abi.h>

/* some helper functions for xen and kvm pv clock sources */
u64 pvclock_clocksource_read(struct pvclock_vcpu_time_info *src);
u8 pvclock_read_flags(struct pvclock_vcpu_time_info *src);
void pvclock_set_flags(u8 flags);
unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src);
void pvclock_resume(void);

void pvclock_touch_watchdogs(void);

static __always_inline
unsigned pvclock_read_begin(const struct pvclock_vcpu_time_info *src)
{
        unsigned version = src->version & ~1;
        /* Make sure that the version is read before the data. */
        rmb();
        return version;
}

static __always_inline
bool pvclock_read_retry(const struct pvclock_vcpu_time_info *src,
                        unsigned version)
{
        /* Make sure that the version is re-read after the data. */
        rmb();
        return version != src->version;
}

/*
 * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
 * yielding a 64-bit result.
 */
static inline u64 pvclock_scale_delta(u64 delta, u32 mul_frac, int shift)
{
        u64 product;
#ifdef __i386__
        u32 tmp1, tmp2;
#else
        unsigned long tmp;
#endif

        if (shift < 0)
                delta >>= -shift;
        else
                delta <<= shift;

#ifdef __i386__
        __asm__ (
                "mul  %5       ; "
                "mov  %4,%%eax ; "
                "mov  %%edx,%4 ; "
                "mul  %5       ; "
                "xor  %5,%5    ; "
                "add  %4,%%eax ; "
                "adc  %5,%%edx ; "
                : "=A" (product), "=r" (tmp1), "=r" (tmp2)
                : "a" ((u32)delta), "1" ((u32)(delta >> 32)), "2" (mul_frac) );
#elif defined(__x86_64__)
        __asm__ (
                "mulq %[mul_frac] ; shrd $32, %[hi], %[lo]"
                : [lo]"=a"(product),
                  [hi]"=d"(tmp)
                : "0"(delta),
                  [mul_frac]"rm"((u64)mul_frac));
#else
#error implement me!
#endif

        return product;
}

static __always_inline
u64 __pvclock_read_cycles(const struct pvclock_vcpu_time_info *src, u64 tsc)
{
        u64 delta = tsc - src->tsc_timestamp;
        u64 offset = pvclock_scale_delta(delta, src->tsc_to_system_mul,
                                             src->tsc_shift);
        return src->system_time + offset;
}

struct pvclock_vsyscall_time_info {
        struct pvclock_vcpu_time_info pvti;
} __attribute__((__aligned__(64)));

#define PVTI_SIZE sizeof(struct pvclock_vsyscall_time_info)

#ifdef CONFIG_PARAVIRT_CLOCK
void pvclock_set_pvti_cpu0_va(struct pvclock_vsyscall_time_info *pvti);
struct pvclock_vsyscall_time_info *pvclock_get_pvti_cpu0_va(void);
#else
static inline struct pvclock_vsyscall_time_info *pvclock_get_pvti_cpu0_va(void)
{
        return NULL;
}
#endif

#endif /* _ASM_X86_PVCLOCK_H */