Extend timer driver API to report also minimal and maximal supported period

lengths. Make MI wrapper code to validate periods in request. Make kernel
clock management code to honor these hardware limitations while choosing hz,
stathz and profhz values.

7 files changed, 90 insertions, 17 deletions

diff --git a/sys/dev/acpica/acpi_hpet.c b/sys/dev/acpica/acpi_hpet.c
index 95f2b32..a789418 100644
--- a/sys/dev/acpica/acpi_hpet.c
+++ b/sys/dev/acpica/acpi_hpet.c
@@ -154,15 +154,16 @@ hpet_start(struct eventtimer *et,
 		t->div = (sc->freq * (period->frac >> 32)) >> 32;
 		if (period->sec != 0)
 			t->div += sc->freq * period->sec;
-		if (first == NULL)
-			first = period;
 	} else {
 		t->mode = 2;
 		t->div = 0;
 	}
-	fdiv = (sc->freq * (first->frac >> 32)) >> 32;
-	if (first->sec != 0)
-		fdiv += sc->freq * first->sec;
+	if (first != NULL) {
+		fdiv = (sc->freq * (first->frac >> 32)) >> 32;
+		if (first->sec != 0)
+			fdiv += sc->freq * first->sec;
+	} else
+		fdiv = t->div;
 	t->last = bus_read_4(sc->mem_res, HPET_MAIN_COUNTER);
 	if (t->mode == 1 && (t->caps & HPET_TCAP_PER_INT)) {
 		t->caps |= HPET_TCNF_TYPE;
@@ -583,6 +584,11 @@ hpet_attach(device_t dev)
 		if ((t->caps & HPET_TCAP_PER_INT) == 0)
 			t->et.et_quality -= 10;
 		t->et.et_frequency = sc->freq;
+		t->et.et_min_period.sec = 0;
+		t->et.et_min_period.frac = 0x00004000LL << 32;
+		t->et.et_max_period.sec = 0xffffffff / sc->freq;
+		t->et.et_max_period.frac =
+		    ((0xffffffffLL << 32) / sc->freq) << 32;
 		t->et.et_start = hpet_start;
 		t->et.et_stop = hpet_stop;
 		t->et.et_priv = &sc->t[i];
diff --git a/sys/kern/kern_clocksource.c b/sys/kern/kern_clocksource.c
index 697275a..9656db6 100644
--- a/sys/kern/kern_clocksource.c
+++ b/sys/kern/kern_clocksource.c
@@ -87,11 +87,9 @@ static DPCPU_DEFINE(tc, configtimer);
 	(bt)->sec = 0;							\
 	(bt)->frac = ((uint64_t)0x8000000000000000  / (freq)) << 1;	\
 }
-#define BT2FREQ(bt, freq)						\
-{									\
-	*(freq) = ((uint64_t)0x8000000000000000 + ((bt)->frac >> 2)) /	\
-		    ((bt)->frac >> 1);					\
-}
+#define BT2FREQ(bt)							\
+	(((uint64_t)0x8000000000000000 + ((bt)->frac >> 2)) /		\
+	    ((bt)->frac >> 1))
 
 /* Per-CPU timer1 handler. */
 static int
@@ -295,6 +293,26 @@ restart:
 #endif
 }
 
+static int
+round_freq(struct eventtimer *et, int freq)
+{
+	uint64_t div;
+
+	if (et->et_frequency != 0) {
+		div = (et->et_frequency + freq / 2) / freq;
+		if (et->et_flags & ET_FLAGS_POW2DIV)
+			div = 1 << (flsl(div + div / 2) - 1);
+		freq = (et->et_frequency + div / 2) / div;
+	}
+	if (et->et_min_period.sec > 0)
+		freq = 0;
+	else if (et->et_max_period.frac != 0)
+		freq = min(freq, BT2FREQ(&et->et_min_period));
+	if (et->et_max_period.sec == 0 && et->et_max_period.frac != 0)
+		freq = max(freq, BT2FREQ(&et->et_max_period));
+	return (freq);
+}
+
 /*
  * Configure and start event timers.
  */
@@ -327,21 +345,25 @@ cpu_initclocks_bsp(void)
 			singlemul = 4;
 	}
 	if (timer[1] == NULL) {
-		base = hz * singlemul;
-		if (base < 128)
+		base = round_freq(timer[0], hz * singlemul);
+		singlemul = max((base + hz / 2) / hz, 1);
+		hz = (base + singlemul / 2) / singlemul;
+		if (base <= 128)
 			stathz = base;
 		else {
 			div = base / 128;
-			if (div % 2 == 0)
+			if (div >= singlemul && (div % singlemul) == 0)
 				div++;
 			stathz = base / div;
 		}
 		profhz = stathz;
-		while ((profhz + stathz) <= 8192)
+		while ((profhz + stathz) <= 128 * 64)
 			profhz += stathz;
+		profhz = round_freq(timer[0], profhz);
 	} else {
-		stathz = 128;
-		profhz = stathz * 64;
+		hz = round_freq(timer[0], hz);
+		stathz = round_freq(timer[1], 127);
+		profhz = round_freq(timer[1], stathz * 64);
 	}
 	ET_LOCK();
 	cpu_restartclocks();
@@ -385,7 +407,9 @@ cpu_restartclocks(void)
 	} else {
 		timer1hz = hz;
 		timer2hz = profiling_on ? profhz : stathz;
+		timer2hz = round_freq(timer[1], timer2hz);
 	}
+	timer1hz = round_freq(timer[0], timer1hz);
 	printf("Starting kernel event timers: %s @ %dHz, %s @ %dHz\n",
 	    timer[0]->et_name, timer1hz,
 	    timer[1] ? timer[1]->et_name : "NONE", timer2hz);
diff --git a/sys/kern/kern_et.c b/sys/kern/kern_et.c
index 52fb705..61a2500 100644
--- a/sys/kern/kern_et.c
+++ b/sys/kern/kern_et.c
@@ -167,6 +167,26 @@ et_start(struct eventtimer *et,
 	if ((et->et_flags & ET_FLAGS_ONESHOT) == 0 &&
 	    period == NULL)
 		return (ENODEV);
+	if (first != NULL) {
+		if (first->sec < et->et_min_period.sec ||
+		    (first->sec == et->et_min_period.sec &&
+		     first->frac < et->et_min_period.frac))
+		        first = &et->et_min_period;
+		if (first->sec > et->et_max_period.sec ||
+		    (first->sec == et->et_max_period.sec &&
+		     first->frac > et->et_max_period.frac))
+		        first = &et->et_max_period;
+	}
+	if (period != NULL) {
+		if (period->sec < et->et_min_period.sec ||
+		    (period->sec == et->et_min_period.sec &&
+		     period->frac < et->et_min_period.frac))
+		        period = &et->et_min_period;
+		if (period->sec > et->et_max_period.sec ||
+		    (period->sec == et->et_max_period.sec &&
+		     period->frac > et->et_max_period.frac))
+		        period = &et->et_max_period;
+	}
 	if (et->et_start)
 		return (et->et_start(et, first, period));
 	return (0);
diff --git a/sys/sys/timeet.h b/sys/sys/timeet.h
index bafa55a..bc713d6 100644
--- a/sys/sys/timeet.h
+++ b/sys/sys/timeet.h
@@ -61,6 +61,7 @@ struct eventtimer {
 #define ET_FLAGS_ONESHOT	2
 #define ET_FLAGS_PERCPU		4
 #define ET_FLAGS_C3STOP		8
+#define ET_FLAGS_POW2DIV	16
 	int			et_quality;
 		/*
 		 * Used to determine if this timecounter is better than
@@ -69,6 +70,8 @@ struct eventtimer {
 	int			et_active;
 	u_int64_t		et_frequency;
 		/* Base frequency in Hz. */
+	struct bintime		et_min_period;
+	struct bintime		et_max_period;
 	et_start_t		*et_start;
 	et_stop_t		*et_stop;
 	et_event_cb_t		*et_event_cb;
diff --git a/sys/x86/isa/atrtc.c b/sys/x86/isa/atrtc.c
index 5a5ba63..b01e933 100644
--- a/sys/x86/isa/atrtc.c
+++ b/sys/x86/isa/atrtc.c
@@ -276,9 +276,13 @@ atrtc_attach(device_t dev)
 			bus_bind_intr(dev, sc->intr_res, 0);
 		}
 		sc->et.et_name = "RTC";
-		sc->et.et_flags = ET_FLAGS_PERIODIC;
+		sc->et.et_flags = ET_FLAGS_PERIODIC | ET_FLAGS_POW2DIV;
 		sc->et.et_quality = 0;
 		sc->et.et_frequency = 32768;
+		sc->et.et_min_period.sec = 0;
+		sc->et.et_min_period.frac = 0x0008LL << 48;
+		sc->et.et_max_period.sec = 0;
+		sc->et.et_max_period.frac = 0x8000LL << 48;
 		sc->et.et_start = rtc_start;
 		sc->et.et_stop = rtc_stop;
 		sc->et.et_priv = dev;
diff --git a/sys/x86/isa/clock.c b/sys/x86/isa/clock.c
index 6b5fede..62869a6 100644
--- a/sys/x86/isa/clock.c
+++ b/sys/x86/isa/clock.c
@@ -665,6 +665,11 @@ attimer_attach(device_t dev)
 		sc->et.et_flags = ET_FLAGS_PERIODIC;
 		sc->et.et_quality = 100;
 		sc->et.et_frequency = i8254_freq;
+		sc->et.et_min_period.sec = 0;
+		sc->et.et_min_period.frac = ((1LL << 62) / i8254_freq) << 2;
+		sc->et.et_max_period.sec = 0xffff / i8254_freq;
+		sc->et.et_max_period.frac =
+		    ((0xffffLL << 48) / i8254_freq) << 16;
 		sc->et.et_start = attimer_start;
 		sc->et.et_stop = attimer_stop;
 		sc->et.et_priv = dev;
diff --git a/sys/x86/x86/local_apic.c b/sys/x86/x86/local_apic.c
index 4364fb1..ffa34a5 100644
--- a/sys/x86/x86/local_apic.c
+++ b/sys/x86/x86/local_apic.c
@@ -263,6 +263,11 @@ lapic_init(vm_paddr_t addr)
 			lapic_et.et_quality -= 100;
 		}
 		lapic_et.et_frequency = 0;
+		/* We don't know frequency yet, so trying to guess. */
+		lapic_et.et_min_period.sec = 0;
+		lapic_et.et_min_period.frac = 0x00001000LL << 32;
+		lapic_et.et_max_period.sec = 1;
+		lapic_et.et_max_period.frac = 0;
 		lapic_et.et_start = lapic_et_start;
 		lapic_et.et_stop = lapic_et_stop;
 		lapic_et.et_priv = NULL;
@@ -493,6 +498,12 @@ lapic_et_start(struct eventtimer *et,
 			printf("lapic: Divisor %lu, Frequency %lu Hz\n",
 			    lapic_timer_divisor, value);
 		et->et_frequency = value;
+		et->et_min_period.sec = 0;
+		et->et_min_period.frac =
+		    ((1LL << 63) / et->et_frequency) << 1;
+		et->et_max_period.sec = 0xffffffff / et->et_frequency;
+		et->et_max_period.frac =
+		    ((0xffffffffLL << 32) / et->et_frequency) << 32;
 	}
 	la = &lapics[lapic_id()];
 	/*