git: d23d186ff212 - main - acpi_timer: Trim some more leftovers from the ACPI-safe timer

The branch main has been updated by jhb:

URL: https://cgit.FreeBSD.org/src/commit/?id=d23d186ff212023c4e1ff61a0f488dc4dcb1b75c

commit d23d186ff212023c4e1ff61a0f488dc4dcb1b75c
Author:     John Baldwin <jhb@FreeBSD.org>
AuthorDate: 2026-09-30 16:04:59 +0000
Commit:     John Baldwin <jhb@FreeBSD.org>
CommitDate: 2026-09-30 16:04:59 +0000

    acpi_timer: Trim some more leftovers from the ACPI-safe timer
    
    The "safe" variant of the hook to read the timer is no longer used and
    can be removed.  Instead, initialize the get_timecount member of
    acpi_timer_timecounter to the normal hook statically.  While here,
    initialize a few more fields in acpi_timer_timecounter statically.
    I've kept the name as just "ACPI" instead of "ACPI-fast" now.
    
    During device probe there is no longer any reason to alloc the
    register resource since it is not used, so remove all that.  While
    here, defer registration of the timecounter until attach (kind of odd
    to do such a thing during probe leaving a window where the timer
    register was unallocated but in theory could still be read via the
    timecounter).
    
    Reviewed by:    cperciva
    Fixes:          00d061855deb ("Garbage-collect ACPI-safe timer and friends")
    Differential Revision:  https://reviews.freebsd.org/D59933
---
 sys/dev/acpica/acpi_timer.c | 82 +++++++++------------------------------------
 1 file changed, 15 insertions(+), 67 deletions(-)

diff --git a/sys/dev/acpica/acpi_timer.c b/sys/dev/acpica/acpi_timer.c
index 08bfa292bf90..6fe0b6b80310 100644
--- a/sys/dev/acpica/acpi_timer.c
+++ b/sys/dev/acpica/acpi_timer.c
@@ -72,7 +72,6 @@ static void	acpi_timer_resume_handler(struct timecounter *,
 static void	acpi_timer_suspend_handler(struct timecounter *,
 		    enum power_stype);
 static u_int	acpi_timer_get_timecount(struct timecounter *tc);
-static u_int	acpi_timer_get_timecount_safe(struct timecounter *tc);
 static int	acpi_timer_sysctl_freq(SYSCTL_HANDLER_ARGS);
 
 static device_method_t acpi_timer_methods[] = {
@@ -93,12 +92,13 @@ DRIVER_MODULE(acpi_timer, acpi, acpi_timer_driver, 0, 0);
 MODULE_DEPEND(acpi_timer, acpi, 1, 1, 1);
 
 static struct timecounter acpi_timer_timecounter = {
-	acpi_timer_get_timecount_safe,	/* get_timecount function */
+	acpi_timer_get_timecount,	/* get_timecount function */
 	0,				/* no poll_pps */
 	0,				/* no default counter_mask */
 	0,				/* no default frequency */
 	"ACPI",				/* name */
-	-1				/* quality (chosen later) */
+	900,				/* quality */
+	TC_FLAGS_SUSPEND_SAFE		/* flags */
 };
 
 static __inline uint32_t
@@ -153,51 +153,14 @@ acpi_timer_identify(driver_t *driver, device_t parent)
 static int
 acpi_timer_probe(device_t dev)
 {
-    int rid, rtype;
-
     ACPI_FUNCTION_TRACE((char *)(uintptr_t)__func__);
 
     if (dev != acpi_timer_dev)
 	return (ENXIO);
 
-    switch (AcpiGbl_FADT.XPmTimerBlock.SpaceId) {
-    case ACPI_ADR_SPACE_SYSTEM_MEMORY:
-	rtype = SYS_RES_MEMORY;
-	break;
-    case ACPI_ADR_SPACE_SYSTEM_IO:
-	rtype = SYS_RES_IOPORT;
-	break;
-    default:
-	return (ENXIO);
-    }
-    rid = 0;
-    acpi_timer_reg = bus_alloc_resource_any(dev, rtype, &rid, RF_ACTIVE);
-    if (acpi_timer_reg == NULL) {
-	device_printf(dev, "couldn't allocate resource (%s 0x%lx)\n",
-	    (rtype == SYS_RES_IOPORT) ? "port" : "mem",
-	    (u_long)AcpiGbl_FADT.XPmTimerBlock.Address);
-	return (ENXIO);
-    }
-    acpi_timer_bsh = rman_get_bushandle(acpi_timer_reg);
-    acpi_timer_bst = rman_get_bustag(acpi_timer_reg);
-    if (AcpiGbl_FADT.Flags & ACPI_FADT_32BIT_TIMER)
-	acpi_timer_timecounter.tc_counter_mask = 0xffffffff;
-    else
-	acpi_timer_timecounter.tc_counter_mask = 0x00ffffff;
-    acpi_timer_timecounter.tc_frequency = acpi_timer_frequency;
-    acpi_timer_timecounter.tc_flags = TC_FLAGS_SUSPEND_SAFE;
-
-    acpi_timer_timecounter.tc_name = "ACPI-fast";
-    acpi_timer_timecounter.tc_get_timecount = acpi_timer_get_timecount;
-    acpi_timer_timecounter.tc_quality = 900;
-    tc_init(&acpi_timer_timecounter);
-
     device_set_descf(dev, "%d-bit timer at %u.%06uMHz",
 	(AcpiGbl_FADT.Flags & ACPI_FADT_32BIT_TIMER) != 0 ? 32 : 24,
 	acpi_timer_frequency / 1000000, acpi_timer_frequency % 1000000);
-
-    /* Release the resource, we'll allocate it again during attach. */
-    bus_release_resource(dev, rtype, rid, acpi_timer_reg);
     return (0);
 }
 
@@ -227,8 +190,19 @@ acpi_timer_attach(device_t dev)
 
     /* Register suspend event handler. */
     if (EVENTHANDLER_REGISTER(power_suspend, acpi_timer_suspend_handler,
-	&acpi_timer_timecounter, EVENTHANDLER_PRI_LAST) == NULL)
+	&acpi_timer_timecounter, EVENTHANDLER_PRI_LAST) == NULL) {
 	device_printf(dev, "failed to register suspend event handler\n");
+	bus_release_resource(dev, acpi_timer_reg);
+	return (ENXIO);
+    }
+
+    if (AcpiGbl_FADT.Flags & ACPI_FADT_32BIT_TIMER)
+	acpi_timer_timecounter.tc_counter_mask = 0xffffffff;
+    else
+	acpi_timer_timecounter.tc_counter_mask = 0x00ffffff;
+    acpi_timer_timecounter.tc_frequency = acpi_timer_frequency;
+
+    tc_init(&acpi_timer_timecounter);
 
     return (0);
 }
@@ -285,38 +259,12 @@ acpi_timer_suspend_handler(struct timecounter *newtc, enum power_stype stype)
 	}
 }
 
-/*
- * Fetch current time value from reliable hardware.
- */
 static u_int
 acpi_timer_get_timecount(struct timecounter *tc)
 {
     return (acpi_timer_read());
 }
 
-/*
- * Fetch current time value from hardware that may not correctly
- * latch the counter.  We need to read until we have three monotonic
- * samples and then use the middle one, otherwise we are not protected
- * against the fact that the bits can be wrong in two directions.  If
- * we only cared about monosity, two reads would be enough.
- */
-static u_int
-acpi_timer_get_timecount_safe(struct timecounter *tc)
-{
-    u_int u1, u2, u3;
-
-    u2 = acpi_timer_read();
-    u3 = acpi_timer_read();
-    do {
-	u1 = u2;
-	u2 = u3;
-	u3 = acpi_timer_read();
-    } while (u1 > u2 || u2 > u3);
-
-    return (u2);
-}
-
 /*
  * Timecounter frequency adjustment interface.
  */