[RFC 11/13] ACPI: Add VIOT table

[Jean-Philippe Brucker <jean-philippe@linaro.org>]

Add support for a new ACPI table that embeds other tables describing a
platform's IOMMU topology. Currently the only supported base table is
IORT. The VIOT contains an IORT with additional node types, that
describe a virtio-iommu.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
 drivers/acpi/Kconfig      |  4 ++++
 drivers/acpi/Makefile     |  1 +
 drivers/acpi/bus.c        |  2 ++
 drivers/acpi/tables.c     |  2 +-
 drivers/acpi/viot.c       | 44 +++++++++++++++++++++++++++++++++++++++
 drivers/iommu/Kconfig     |  1 +
 include/linux/acpi_viot.h | 20 ++++++++++++++++++
 7 files changed, 73 insertions(+), 1 deletion(-)
 create mode 100644 drivers/acpi/viot.c
 create mode 100644 include/linux/acpi_viot.h

diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index 548976c8b2b0..513a5e4d3526 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -579,6 +579,10 @@ config TPS68470_PMIC_OPREGION
 config ACPI_IORT
 	bool
 
+config ACPI_VIOT
+	bool
+	select ACPI_IORT
+
 endif	# ACPI
 
 config X86_PM_TIMER
diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index 9d1792165713..6abdc6cc32c7 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -124,3 +124,4 @@ obj-y				+= dptf/
 
 obj-$(CONFIG_ARM64)		+= arm64/
 obj-$(CONFIG_ACPI_IORT) 	+= iort.o
+obj-$(CONFIG_ACPI_VIOT)		+= viot.o
diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index 48bc96d45bab..6f364e0c9240 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -25,6 +25,7 @@
 #include <linux/dmi.h>
 #endif
 #include <linux/acpi_iort.h>
+#include <linux/acpi_viot.h>
 #include <linux/pci.h>
 #include <acpi/apei.h>
 #include <linux/suspend.h>
@@ -1246,6 +1247,7 @@ static int __init acpi_init(void)
 
 	pci_mmcfg_late_init();
 	acpi_iort_init();
+	acpi_viot_init();
 	acpi_scan_init();
 	acpi_ec_init();
 	acpi_debugfs_init();
diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c
index 180ac4329763..9662ea5e1064 100644
--- a/drivers/acpi/tables.c
+++ b/drivers/acpi/tables.c
@@ -501,7 +501,7 @@ static const char * const table_sigs[] = {
 	ACPI_SIG_WDDT, ACPI_SIG_WDRT, ACPI_SIG_DSDT, ACPI_SIG_FADT,
 	ACPI_SIG_PSDT, ACPI_SIG_RSDT, ACPI_SIG_XSDT, ACPI_SIG_SSDT,
 	ACPI_SIG_IORT, ACPI_SIG_NFIT, ACPI_SIG_HMAT, ACPI_SIG_PPTT,
-	NULL };
+	ACPI_SIG_VIOT, NULL };
 
 #define ACPI_HEADER_SIZE sizeof(struct acpi_table_header)
 
diff --git a/drivers/acpi/viot.c b/drivers/acpi/viot.c
new file mode 100644
index 000000000000..ab9a6e43ad9b
--- /dev/null
+++ b/drivers/acpi/viot.c
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2019 Linaro
+ *
+ * Virtual IOMMU table
+ */
+#define pr_fmt(fmt)	"ACPI: VIOT: " fmt
+
+#include <linux/acpi.h>
+#include <linux/acpi_iort.h>
+#include <linux/acpi_viot.h>
+
+int __init acpi_viot_init(void)
+{
+	struct acpi_table_viot *viot;
+	struct acpi_table_header *acpi_header;
+	acpi_status status;
+
+	status = acpi_get_table(ACPI_SIG_VIOT, 0, &acpi_header);
+	if (ACPI_FAILURE(status)) {
+		if (status != AE_NOT_FOUND) {
+			const char *msg = acpi_format_exception(status);
+
+			pr_err("Failed to get table, %s\n", msg);
+			return -EINVAL;
+		}
+
+		return 0;
+	}
+
+	if (acpi_header->length < sizeof(*viot)) {
+		pr_err("VIOT table overflow, bad table!\n");
+		return -EINVAL;
+	}
+
+	viot = (struct acpi_table_viot *)acpi_header;
+	if (ACPI_COMPARE_NAMESEG(viot->base_table.signature, ACPI_SIG_IORT)) {
+		acpi_iort_register_table(&viot->base_table, IORT_SOURCE_VIOT);
+		return 0;
+	}
+
+	pr_err("Unknown base table header\n");
+	return -EINVAL;
+}
diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index e3842eabcfdd..e6eb4f238d1a 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -480,6 +480,7 @@ config VIRTIO_IOMMU
 	depends on ARM64
 	select IOMMU_API
 	select INTERVAL_TREE
+	select ACPI_VIOT if ACPI
 	help
 	  Para-virtualised IOMMU driver with virtio.
 
diff --git a/include/linux/acpi_viot.h b/include/linux/acpi_viot.h
new file mode 100644
index 000000000000..6c282d5eb793
--- /dev/null
+++ b/include/linux/acpi_viot.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2019 Linaro
+ */
+
+#ifndef __ACPI_VIOT_H__
+#define __ACPI_VIOT_H__
+
+#ifdef CONFIG_ACPI_VIOT
+
+int acpi_viot_init(void);
+
+#else /* !CONFIG_ACPI_VIOT */
+
+static inline int acpi_viot_init(void)
+{}
+
+#endif /* !CONFIG_ACPI_VIOT */
+
+#endif /* __ACPI_VIOT_H__ */
-- 
2.24.0