Orange Pi5 kernel

/* SPDX-License-Identifier: GPL-2.0 */
 
/*
 * Definitions for the clocksource provided by the Hyper-V
 * hypervisor to guest VMs, as described in the Hyper-V Top
 * Level Functional Spec (TLFS).
 *
 * Copyright (C) 2019, Microsoft, Inc.
 *
 * Author:  Michael Kelley <mikelley@microsoft.com>
 */
 
#ifndef __CLKSOURCE_HYPERV_TIMER_H
#define __CLKSOURCE_HYPERV_TIMER_H
 
#include <linux/clocksource.h>
#include <linux/math64.h>
#include <asm/mshyperv.h>
 
#define HV_MAX_MAX_DELTA_TICKS 0xffffffff
#define HV_MIN_DELTA_TICKS 1
 
/* Routines called by the VMbus driver */
extern int hv_stimer_alloc(void);
extern void hv_stimer_free(void);
extern int hv_stimer_cleanup(unsigned int cpu);
extern void hv_stimer_legacy_init(unsigned int cpu, int sint);
extern void hv_stimer_legacy_cleanup(unsigned int cpu);
extern void hv_stimer_global_cleanup(void);
extern void hv_stimer0_isr(void);
 
#ifdef CONFIG_HYPERV_TIMER
extern u64 (*hv_read_reference_counter)(void);
extern void hv_init_clocksource(void);
 
extern struct ms_hyperv_tsc_page *hv_get_tsc_page(void);
 
static inline notrace u64
hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg, u64 *cur_tsc)
{
<------>u64 scale, offset;
<------>u32 sequence;
 
<------>/*
<------> * The protocol for reading Hyper-V TSC page is specified in Hypervisor
<------> * Top-Level Functional Specification ver. 3.0 and above. To get the
<------> * reference time we must do the following:
<------> * - READ ReferenceTscSequence
<------> *   A special '0' value indicates the time source is unreliable and we
<------> *   need to use something else. The currently published specification
<------> *   versions (up to 4.0b) contain a mistake and wrongly claim '-1'
<------> *   instead of '0' as the special value, see commit c35b82ef0294.
<------> * - ReferenceTime =
<------> *        ((RDTSC() * ReferenceTscScale) >> 64) + ReferenceTscOffset
<------> * - READ ReferenceTscSequence again. In case its value has changed
<------> *   since our first reading we need to discard ReferenceTime and repeat
<------> *   the whole sequence as the hypervisor was updating the page in
<------> *   between.
<------> */
<------>do {
<------><------>sequence = READ_ONCE(tsc_pg->tsc_sequence);
<------><------>if (!sequence)
<------><------><------>return U64_MAX;
<------><------>/*
<------><------> * Make sure we read sequence before we read other values from
<------><------> * TSC page.
<------><------> */
<------><------>smp_rmb();
 
<------><------>scale = READ_ONCE(tsc_pg->tsc_scale);
<------><------>offset = READ_ONCE(tsc_pg->tsc_offset);
<------><------>*cur_tsc = hv_get_raw_timer();
 
<------><------>/*
<------><------> * Make sure we read sequence after we read all other values
<------><------> * from TSC page.
<------><------> */
<------><------>smp_rmb();
 
<------>} while (READ_ONCE(tsc_pg->tsc_sequence) != sequence);
 
<------>return mul_u64_u64_shr(*cur_tsc, scale, 64) + offset;
}
 
static inline notrace u64
hv_read_tsc_page(const struct ms_hyperv_tsc_page *tsc_pg)
{
<------>u64 cur_tsc;
 
<------>return hv_read_tsc_page_tsc(tsc_pg, &cur_tsc);
}
 
#else /* CONFIG_HYPERV_TIMER */
static inline struct ms_hyperv_tsc_page *hv_get_tsc_page(void)
{
<------>return NULL;
}
 
static inline u64 hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg,
<------><------><------><------>       u64 *cur_tsc)
{
<------>return U64_MAX;
}
#endif /* CONFIG_HYPERV_TIMER */
 
#endif