svn commit: r203062 - head/sys/dev/acpica

Andriy Gapon avg at FreeBSD.org
Wed Jan 27 10:17:29 UTC 2010


Author: avg
Date: Wed Jan 27 10:17:28 2010
New Revision: 203062
URL: http://svn.freebsd.org/changeset/base/203062

Log:
  acpi_hpet: correctly get number of timers/comparators in a timer block
  
  Also, account for a quirk of AMD/ATI HPET which reports number of timers
  instead of id of the last timer as manadated by the specification.
  Currently this has no effect on functionality but in the future we may
  make actual use of the HPET timers, not only of its timecounter.
  
  MFC after:	2 weeks

Modified:
  head/sys/dev/acpica/acpi_hpet.c

Modified: head/sys/dev/acpica/acpi_hpet.c
==============================================================================
--- head/sys/dev/acpica/acpi_hpet.c	Wed Jan 27 09:59:08 2010	(r203061)
+++ head/sys/dev/acpica/acpi_hpet.c	Wed Jan 27 10:17:28 2010	(r203062)
@@ -42,6 +42,9 @@ __FBSDID("$FreeBSD$");
 #include <dev/acpica/acpivar.h>
 #include <dev/acpica/acpi_hpet.h>
 
+#define HPET_VENDID_AMD		0x4353
+#define HPET_VENDID_INTEL	0x8086
+
 ACPI_SERIAL_DECL(hpet, "ACPI HPET support");
 
 static devclass_t acpi_hpet_devclass;
@@ -155,9 +158,10 @@ static int
 acpi_hpet_attach(device_t dev)
 {
 	struct acpi_hpet_softc *sc;
-	int rid;
+	int rid, num_timers;
 	uint32_t val, val2;
 	uintmax_t freq;
+	uint16_t vendor;
 
 	ACPI_FUNCTION_TRACE((char *)(uintptr_t) __func__);
 
@@ -194,10 +198,21 @@ acpi_hpet_attach(device_t dev)
 	freq = (1000000000000000LL + val / 2) / val;
 	if (bootverbose) {
 		val = bus_read_4(sc->mem_res, HPET_CAPABILITIES);
+
+		/*
+		 * ATI/AMD violates IA-PC HPET (High Precision Event Timers)
+		 * Specification and provides an off by one number
+		 * of timers/comparators.
+		 * Additionally, they use unregistered value in VENDOR_ID field.
+		 */
+		num_timers = 1 + ((val & HPET_CAP_NUM_TIM) >> 8);
+		vendor = val >> 16;
+		if (vendor == HPET_VENDID_AMD && num_timers > 0)
+			num_timers--;
 		device_printf(dev,
 		    "vend: 0x%x rev: 0x%x num: %d hz: %jd opts:%s%s\n",
-		    val >> 16, val & HPET_CAP_REV_ID,
-		    (val & HPET_CAP_NUM_TIM) >> 8, freq,
+		    vendor, val & HPET_CAP_REV_ID,
+		    num_timers, freq,
 		    (val & HPET_CAP_LEG_RT) ? " legacy_route" : "",
 		    (val & HPET_CAP_COUNT_SIZE) ? " 64-bit" : "");
 	}


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