On 06/15/2016 01:04 PM, Lorenzo Pieralisi wrote:

On Mon, Jun 13, 2016 at 04:41:07PM +0200, Tomasz Nowicki wrote:

quoted

IORT shows representation of IO topology for ARM based systems.
It describes how various components are connected together on
parent-child basis e.g. PCI RC -> SMMU -> ITS. Also see IORT spec.

Initial support allows to:
- register ITS MSI chip along with ITS translation ID and domain token
- deregister ITS MSI chip based on ITS translation ID
- find registered domain token based on ITS translation ID
- map MSI RID for a device
- find domain token for a device

Signed-off-by: Tomasz Nowicki <redacted>
---
  drivers/acpi/Kconfig  |   3 +
  drivers/acpi/Makefile |   1 +
  drivers/acpi/iort.c   | 386 ++++++++++++++++++++++++++++++++++++++++++++++++++
  include/linux/iort.h  |  38 +++++
  4 files changed, 428 insertions(+)
  create mode 100644 drivers/acpi/iort.c
  create mode 100644 include/linux/iort.h

diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index f98c328..111dd50 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig

@@ -57,6 +57,9 @@ config ACPI_SYSTEM_POWER_STATES_SUPPORT
  config ACPI_CCA_REQUIRED
  	bool
  
+config IORT_TABLE
+	bool
+
  config ACPI_DEBUGGER
  	bool "AML debugger interface"
  	select ACPI_DEBUG

diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index 632e81f..0390f27 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile

@@ -83,6 +83,7 @@ obj-$(CONFIG_ACPI_CUSTOM_METHOD)+= custom_method.o
  obj-$(CONFIG_ACPI_BGRT)		+= bgrt.o
  obj-$(CONFIG_ACPI_CPPC_LIB)	+= cppc_acpi.o
  obj-$(CONFIG_ACPI_DEBUGGER_USER) += acpi_dbg.o
+obj-$(CONFIG_IORT_TABLE) 	+= iort.o
  
  # processor has its own "processor." module_param namespace
  processor-y			:= processor_driver.o

diff --git a/drivers/acpi/iort.c b/drivers/acpi/iort.c
new file mode 100644
index 0000000..5bccbc8
--- /dev/null
+++ b/drivers/acpi/iort.c

@@ -0,0 +1,386 @@
+/*
+ * Copyright (C) 2016, Semihalf
+ *	Author: Tomasz Nowicki <tn@semihalf.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * This file implements early detection/parsing of I/O mapping
+ * reported to OS through firmware via I/O Remapping Table (IORT)
+ * IORT document number: ARM DEN 0049A
+ */
+
+#define pr_fmt(fmt)	"ACPI: IORT: " fmt
+
+#include <linux/export.h>
+#include <linux/iort.h>
+#include <linux/irqdomain.h>
+#include <linux/kernel.h>
+#include <linux/pci.h>
+
+struct iort_its_msi_chip {
+	struct list_head	list;
+	struct fwnode_handle	*fw_node;
+	u32			translation_id;
+};
+
+typedef acpi_status (*iort_find_node_callback)
+	(struct acpi_iort_node *node, void *context);
+
+/* Root pointer to the mapped IORT table */
+static struct acpi_table_header *iort_table;

A question to be sorted out:

We assume we can rely on the iort_table pointer, obtained through
acpi_get_table(), since we assume acpi_glb_permanent_mmap is set (?),
correct ?

Correct.

x86 DMAR code seems to rely on that (without even checking
acpi_gbl_permanent_mmap) and this has consequences on when
we can really start parsing IORT entries through this patch
(because if acpi_gbl_permanent_mmap is not set while using
IORT nodes we would dereference unmapped pointers).

@Rafael: can you confirm that's the right approach ?

Thanks,
Tomasz