From cf0afdaab6c385be40c95a079dc2f0de670d40ea Mon Sep 17 00:00:00 2001
From: Andrew Turner <andrew@FreeBSD.org>
Date: Wed, 28 Feb 2018 15:25:47 +0000
Subject: [PATCH] Count the number of GIC redistributors in the ACPI tables.
 The GICv3 driver needs this to allocate memory, and connect the CPUs to the
 interrupt controller.

Sponsored by:	DARPA, AFRL
Sponsored by:	Cavium (Hardware)
---
 sys/arm64/arm64/gic_v3_acpi.c | 40 +++++++++++++++++++++++++++++++++--
 1 file changed, 38 insertions(+), 2 deletions(-)

diff --git a/sys/arm64/arm64/gic_v3_acpi.c b/sys/arm64/arm64/gic_v3_acpi.c
index 8235bd33919..00a5e371208 100644
--- a/sys/arm64/arm64/gic_v3_acpi.c
+++ b/sys/arm64/arm64/gic_v3_acpi.c
@@ -206,6 +206,41 @@ gic_v3_acpi_probe(device_t dev)
 	return (BUS_PROBE_NOWILDCARD);
 }
 
+static void
+madt_count_redistrib(ACPI_SUBTABLE_HEADER *entry, void *arg)
+{
+	struct gic_v3_softc *sc = arg;
+
+	if (entry->Type == ACPI_MADT_TYPE_GENERIC_REDISTRIBUTOR)
+		sc->gic_redists.nregions++;
+}
+
+static int
+gic_v3_acpi_count_regions(device_t dev)
+{
+	struct gic_v3_softc *sc;
+	ACPI_TABLE_MADT *madt;
+	vm_paddr_t physaddr;
+
+	sc = device_get_softc(dev);
+
+	physaddr = acpi_find_table(ACPI_SIG_MADT);
+	if (physaddr == 0)
+		return (ENXIO);
+
+	madt = acpi_map_table(physaddr, ACPI_SIG_MADT);
+	if (madt == NULL) {
+		device_printf(dev, "Unable to map the MADT\n");
+		return (ENXIO);
+	}
+
+	acpi_walk_subtables(madt + 1, (char *)madt + madt->Header.Length,
+	    madt_count_redistrib, sc);
+	acpi_unmap_table(madt);
+
+	return (sc->gic_redists.nregions > 0 ? 0 : ENXIO);
+}
+
 static int
 gic_v3_acpi_attach(device_t dev)
 {
@@ -216,8 +251,9 @@ gic_v3_acpi_attach(device_t dev)
 	sc->dev = dev;
 	sc->gic_bus = GIC_BUS_ACPI;
 
-	/* TODO: Count these correctly */
-	sc->gic_redists.nregions = 1;
+	err = gic_v3_acpi_count_regions(dev);
+	if (err != 0)
+		goto error;
 
 	err = gic_v3_attach(dev);
 	if (err != 0)