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.

1 files changed, 35 insertions, 11 deletions

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);