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drivers: hv: Decouple Hyper-V clock/timer code from VMbus drivers 

Hyper-V clock/timer code in hyperv_timer.c is mostly independent from
other VMbus drivers, but building for ARM64 without hyperv_timer.c
shows some remaining entanglements.  A default implementation of
hv_read_reference_counter can just read a Hyper-V synthetic register
and be independent of hyperv_timer.c, so move this code out and into
hv_common.c. Then it can be used by the timesync driver even if
hyperv_timer.c isn't built on a particular architecture.  If
hyperv_timer.c *is* built, it can override with a faster implementation.

Also provide stubs for stimer functions called by the VMbus driver when
hyperv_timer.c isn't built.

No functional changes.

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/1626220906-22629-1-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
This commit is contained in:
Michael Kelley 2021-07-13 17:01:46 -07:00 committed by Wei Liu
parent 5f92b45c3b
commit 31e5e64694
5 changed files with 25 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
drivers/clocksource/hyperv_timer.c
View File

@ -361,9 +361,6 @@ EXPORT_SYMBOL_GPL(hv_stimer_global_cleanup);
* Hyper-V and 32-bit x86. The TSC reference page version is preferred.
*/
u64 (*hv_read_reference_counter)(void);
EXPORT_SYMBOL_GPL(hv_read_reference_counter);
static union {
struct ms_hyperv_tsc_page page;
u8 reserved[PAGE_SIZE];

14
drivers/hv/hv_common.c
View File

@ -222,6 +222,20 @@ bool hv_is_hibernation_supported(void)
}
EXPORT_SYMBOL_GPL(hv_is_hibernation_supported);
/*
* Default function to read the Hyper-V reference counter, independent
* of whether Hyper-V enlightened clocks/timers are being used. But on
* architectures where it is used, Hyper-V enlightenment code in
* hyperv_timer.c may override this function.
*/
static u64 __hv_read_ref_counter(void)
{
return hv_get_register(HV_REGISTER_TIME_REF_COUNT);
}
u64 (*hv_read_reference_counter)(void) = __hv_read_ref_counter;
EXPORT_SYMBOL_GPL(hv_read_reference_counter);
/* These __weak functions provide default "no-op" behavior and
* may be overridden by architecture specific versions. Architectures
* for which the default "no-op" behavior is sufficient can leave

5
drivers/hv/hv_util.c
View File

@ -17,7 +17,6 @@
#include <linux/hyperv.h>
#include <linux/clockchips.h>
#include <linux/ptp_clock_kernel.h>
#include <clocksource/hyperv_timer.h>
#include <asm/mshyperv.h>
#include "hyperv_vmbus.h"
@ -735,10 +734,6 @@ static struct ptp_clock *hv_ptp_clock;
static int hv_timesync_init(struct hv_util_service *srv)
{
/* TimeSync requires Hyper-V clocksource. */
if (!hv_read_reference_counter)
return -ENODEV;
spin_lock_init(&host_ts.lock);
INIT_WORK(&adj_time_work, hv_set_host_time);

2
include/asm-generic/mshyperv.h
View File

@ -167,6 +167,8 @@ extern bool hv_root_partition;
extern u32 *hv_vp_index;
extern u32 hv_max_vp_index;
extern u64 (*hv_read_reference_counter)(void);
/* Sentinel value for an uninitialized entry in hv_vp_index array */
#define VP_INVAL U32_MAX

11
include/clocksource/hyperv_timer.h
View File

@ -20,6 +20,8 @@
#define HV_MAX_MAX_DELTA_TICKS 0xffffffff
#define HV_MIN_DELTA_TICKS 1
#ifdef CONFIG_HYPERV_TIMER
/* Routines called by the VMbus driver */
extern int hv_stimer_alloc(bool have_percpu_irqs);
extern int hv_stimer_cleanup(unsigned int cpu);
@ -28,8 +30,6 @@ 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);
@ -100,6 +100,13 @@ static inline u64 hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg,
{
return U64_MAX;
}
static inline int hv_stimer_cleanup(unsigned int cpu) { return 0; }
static inline void hv_stimer_legacy_init(unsigned int cpu, int sint) {}
static inline void hv_stimer_legacy_cleanup(unsigned int cpu) {}
static inline void hv_stimer_global_cleanup(void) {}
static inline void hv_stimer0_isr(void) {}
#endif /* CONFIG_HYPERV_TIMER */
#endif