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Implement a HPET based DELAY().

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This commit is contained in:
ad 2020-04-23 20:33:57 +00:00
parent d8fa6d0b7a
commit e5210a69c7
2 changed files with 53 additions and 6 deletions
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52
sys/dev/ic/hpet.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: hpet.c,v 1.13 2011/10/31 12:47:15 yamt Exp $ */
/* $NetBSD: hpet.c,v 1.14 2020/04/23 20:33:57 ad Exp $ */
/*
* Copyright (c) 2006 Nicolas Joly
@ -33,7 +33,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: hpet.c,v 1.13 2011/10/31 12:47:15 yamt Exp $");
__KERNEL_RCSID(0, "$NetBSD: hpet.c,v 1.14 2020/04/23 20:33:57 ad Exp $");
#include <sys/systm.h>
#include <sys/device.h>
@ -43,6 +43,7 @@ __KERNEL_RCSID(0, "$NetBSD: hpet.c,v 1.13 2011/10/31 12:47:15 yamt Exp $");
#include <sys/timetc.h>
#include <sys/bus.h>
#include <sys/lock.h>
#include <dev/ic/hpetreg.h>
#include <dev/ic/hpetvar.h>
@ -50,9 +51,12 @@ __KERNEL_RCSID(0, "$NetBSD: hpet.c,v 1.13 2011/10/31 12:47:15 yamt Exp $");
static u_int hpet_get_timecount(struct timecounter *);
static bool hpet_resume(device_t, const pmf_qual_t *);
static struct hpet_softc *hpet0 __read_mostly;
int
hpet_detach(device_t dv, int flags)
{
#if 0 /* XXX DELAY() is based off this, detaching is not a good idea. */
struct hpet_softc *sc = device_private(dv);
int rc;
@ -64,6 +68,9 @@ hpet_detach(device_t dv, int flags)
bus_space_write_4(sc->sc_memt, sc->sc_memh, HPET_CONFIG, sc->sc_config);
return 0;
#else
return EBUSY;
#endif
}
void
@ -84,8 +91,8 @@ hpet_attach_subr(device_t dv)
tc->tc_counter_mask = 0xffffffff;
/* Get frequency */
val = bus_space_read_4(sc->sc_memt, sc->sc_memh, HPET_PERIOD);
if (val == 0 || val > HPET_PERIOD_MAX) {
sc->sc_period = bus_space_read_4(sc->sc_memt, sc->sc_memh, HPET_PERIOD);
if (sc->sc_period == 0 || sc->sc_period > HPET_PERIOD_MAX) {
aprint_error_dev(dv, "invalid timer period\n");
return;
}
@ -104,7 +111,7 @@ hpet_attach_subr(device_t dv)
}
}
tmp = (1000000000000000ULL * 2) / val;
tmp = (1000000000000000ULL * 2) / sc->sc_period;
tc->tc_frequency = (tmp / 2) + (tmp & 1);
/* Enable timer */
@ -120,6 +127,9 @@ hpet_attach_subr(device_t dv)
if (!pmf_device_register(dv, NULL, hpet_resume))
aprint_error_dev(dv, "couldn't establish power handler\n");
if (device_unit(dv) == 0)
hpet0 = sc;
}
static u_int
@ -143,6 +153,38 @@ hpet_resume(device_t dv, const pmf_qual_t *qual)
return true;
}
bool
hpet_delay_p(void)
{
return hpet0 != NULL;
}
void
hpet_delay(unsigned int us)
{
struct hpet_softc *sc;
uint32_t ntick, otick;
int64_t delta;
/*
* Read timer before slow division. Assume that each read of the
* HPET costs ~500ns. Aim for the middle and subtract 750ns for
* overhead.
*/
sc = hpet0;
otick = bus_space_read_4(sc->sc_memt, sc->sc_memh, HPET_MCOUNT_LO);
delta = (((int64_t)us * 1000000000) - 750000000) / sc->sc_period;
while (delta > 0) {
SPINLOCK_BACKOFF_HOOK;
ntick = bus_space_read_4(sc->sc_memt, sc->sc_memh,
HPET_MCOUNT_LO);
delta -= (uint32_t)(ntick - otick);
otick = ntick;
}
}
MODULE(MODULE_CLASS_DRIVER, hpet, NULL);
#ifdef _MODULE

7
sys/dev/ic/hpetvar.h
View File

@ -1,4 +1,4 @@
/* $NetBSD: hpetvar.h,v 1.4 2011/06/14 16:33:51 jruoho Exp $ */
/* $NetBSD: hpetvar.h,v 1.5 2020/04/23 20:33:57 ad Exp $ */
/*
* Copyright (c) 2006 Nicolas Joly
@ -31,6 +31,8 @@
#ifndef _DEV_IC_HPETVAR_H_
#define _DEV_IC_HPETVAR_H_
#include <sys/timetc.h>
struct hpet_softc {
bus_size_t sc_mems;
bus_space_tag_t sc_memt;
@ -38,10 +40,13 @@ struct hpet_softc {
bool sc_mapped;
uint32_t sc_config;
int32_t sc_period;
struct timecounter sc_tc;
};
void hpet_attach_subr(device_t);
int hpet_detach(device_t, int flags);
void hpet_delay(unsigned int);
bool hpet_delay_p(void);
#endif /* _DEV_IC_HPETVAR_H_ */