From 3c4c08dce7cf4d12114ff81b4e41012257ed0d6c Mon Sep 17 00:00:00 2001
From: Alexander Motin <mav@FreeBSD.org>
Date: Sun, 23 May 2010 07:53:22 +0000
Subject: [PATCH] Make table-based HPET identification more clever. Before
 creating fake device, make sure we have no real HPET device entry with same
 ID. As side effect, it potentially allows several HPETs to be attached. Use
 first of them for timecounting, rest (if ever present) could later be used as
 event sources.

---
 sys/dev/acpica/acpi.c      |  3 +-
 sys/dev/acpica/acpi_hpet.c | 79 +++++++++++++++++++++++---------------
 sys/dev/acpica/acpivar.h   |  1 +
 3 files changed, 51 insertions(+), 32 deletions(-)

diff --git a/sys/dev/acpica/acpi.c b/sys/dev/acpica/acpi.c
index 64a331823825..621c217441e0 100644
--- a/sys/dev/acpica/acpi.c
+++ b/sys/dev/acpica/acpi.c
@@ -145,7 +145,6 @@ static void	acpi_probe_children(device_t bus);
 static void	acpi_probe_order(ACPI_HANDLE handle, int *order);
 static ACPI_STATUS acpi_probe_child(ACPI_HANDLE handle, UINT32 level,
 		    void *context, void **status);
-static BOOLEAN	acpi_MatchHid(ACPI_HANDLE h, const char *hid);
 static void	acpi_sleep_enable(void *arg);
 static ACPI_STATUS acpi_sleep_disable(struct acpi_softc *sc);
 static ACPI_STATUS acpi_EnterSleepState(struct acpi_softc *sc, int state);
@@ -1944,7 +1943,7 @@ acpi_BatteryIsPresent(device_t dev)
 /*
  * Match a HID string against a handle
  */
-static BOOLEAN
+BOOLEAN
 acpi_MatchHid(ACPI_HANDLE h, const char *hid) 
 {
     ACPI_DEVICE_INFO	*devinfo;
diff --git a/sys/dev/acpica/acpi_hpet.c b/sys/dev/acpica/acpi_hpet.c
index a98a8260f953..1288494adbad 100644
--- a/sys/dev/acpica/acpi_hpet.c
+++ b/sys/dev/acpica/acpi_hpet.c
@@ -101,41 +101,60 @@ hpet_disable(struct acpi_hpet_softc *sc)
 	bus_write_4(sc->mem_res, HPET_CONFIG, val);
 }
 
+static ACPI_STATUS
+acpi_hpet_find(ACPI_HANDLE handle, UINT32 level, void *context,
+    void **status)
+{
+	char 		**ids;
+	uint32_t	id = (uint32_t)(uintptr_t)context;
+	uint32_t	adr = 0;
+
+	for (ids = hpet_ids; *ids != NULL; ids++) {
+		if (acpi_MatchHid(handle, *ids))
+		        break;
+	}
+	if (*ids == NULL)
+		return (AE_OK);
+	if (ACPI_FAILURE(acpi_GetInteger(handle, "_ADR", &adr)))
+		adr = 0;
+	if (id == adr)
+		*((int *)status) = 1;
+	return (AE_OK);
+}
+
 /* Discover the HPET via the ACPI table of the same name. */
 static void 
 acpi_hpet_identify(driver_t *driver, device_t parent)
 {
 	ACPI_TABLE_HPET *hpet;
-	ACPI_TABLE_HEADER *hdr;
 	ACPI_STATUS	status;
 	device_t	child;
+	int 		i, found;
 
 	/* Only one HPET device can be added. */
 	if (devclass_get_device(acpi_hpet_devclass, 0))
 		return;
-
-	/* Currently, ID and minimum clock tick info is unused. */
-
-	status = AcpiGetTable(ACPI_SIG_HPET, 1, (ACPI_TABLE_HEADER **)&hdr);
-	if (ACPI_FAILURE(status))
-		return;
-
-	/*
-	 * The unit number could be derived from hdr->Sequence but we only
-	 * support one HPET device.
-	 */
-	hpet = (ACPI_TABLE_HPET *)hdr;
-	if (hpet->Sequence != 0)
-		printf("ACPI HPET table warning: Sequence is non-zero (%d)\n",
-		    hpet->Sequence);
-	child = BUS_ADD_CHILD(parent, ACPI_DEV_BASE_ORDER, "acpi_hpet", 0);
-	if (child == NULL) {
-		printf("%s: can't add child\n", __func__);
-		return;
+	for (i = 1; ; i++) {
+		/* Search for HPET table. */
+		status = AcpiGetTable(ACPI_SIG_HPET, i, (ACPI_TABLE_HEADER **)&hpet);
+		if (ACPI_FAILURE(status))
+			return;
+		/* Search for HPET device with same ID. */
+		found = 0;
+		AcpiWalkNamespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
+		    100, acpi_hpet_find, NULL, (void *)(uintptr_t)hpet->Sequence, (void *)&found);
+		/* If found - let it be probed in normal way. */
+		if (found)
+			continue;
+		/* If not - create it from table info. */
+		child = BUS_ADD_CHILD(parent, ACPI_DEV_BASE_ORDER, "acpi_hpet", 0);
+		if (child == NULL) {
+			printf("%s: can't add child\n", __func__);
+			continue;
+		}
+		bus_set_resource(child, SYS_RES_MEMORY, 0, hpet->Address.Address,
+		    HPET_MEM_WIDTH);
 	}
-
-	bus_set_resource(child, SYS_RES_MEMORY, 0, hpet->Address.Address,
-	    HPET_MEM_WIDTH);
 }
 
 static int
@@ -146,8 +165,7 @@ acpi_hpet_probe(device_t dev)
 	if (acpi_disabled("hpet"))
 		return (ENXIO);
 	if (acpi_get_handle(dev) != NULL &&
-	    (ACPI_ID_PROBE(device_get_parent(dev), dev, hpet_ids) == NULL ||
-	    device_get_unit(dev) != 0))
+	    ACPI_ID_PROBE(device_get_parent(dev), dev, hpet_ids) == NULL)
 		return (ENXIO);
 
 	device_set_desc(dev, "High Precision Event Timer");
@@ -233,11 +251,12 @@ acpi_hpet_attach(device_t dev)
 		bus_free_resource(dev, SYS_RES_MEMORY, sc->mem_res);
 		return (ENXIO);
 	}
-
-	hpet_timecounter.tc_frequency = freq;
-	hpet_timecounter.tc_priv = sc;
-	tc_init(&hpet_timecounter);
-
+	/* Announce first HPET as timecounter. */
+	if (device_get_unit(dev) == 0) {
+		hpet_timecounter.tc_frequency = freq;
+		hpet_timecounter.tc_priv = sc;
+		tc_init(&hpet_timecounter);
+	}
 	return (0);
 }
 
diff --git a/sys/dev/acpica/acpivar.h b/sys/dev/acpica/acpivar.h
index 002c11c91a71..adc9d6ea66c0 100644
--- a/sys/dev/acpica/acpivar.h
+++ b/sys/dev/acpica/acpivar.h
@@ -342,6 +342,7 @@ int		acpi_bus_alloc_gas(device_t dev, int *type, int *rid,
 		    u_int flags);
 void		acpi_walk_subtables(void *first, void *end,
 		    acpi_subtable_handler *handler, void *arg);
+BOOLEAN		acpi_MatchHid(ACPI_HANDLE h, const char *hid);
 
 struct acpi_parse_resource_set {
     void	(*set_init)(device_t dev, void *arg, void **context);