[PATCH v3 0/3] RISC-V: Add ACPI support for IOMMU

[PATCH v3 0/3] RISC-V: Add ACPI support for IOMMU

[Sunil V L]

This series adds support for RISC-V IOMMU on ACPI based platforms.
RISC-V IO Mapping Table (RIMT) is a new static ACPI table [1] introduced
to communicate IOMMU information to the OS.

[1] - https://github.com/riscv-non-isa/riscv-acpi-rimt/releases/download/v1.0/rimt-spec.pdf

Changes since v2:
	1) Rebased to 6.16-rc4
	2) Removed Anup's SOB and link tags added by mistake in v2.

Changes since v1:
	1) Rebased to v6.16-rc1.
	2) Dropped ACPICA patch since it is already available in 6.16-rc1.
	3) Added Rafael's ACK.
	4) Fixed few issues found by bots.


Sunil V L (3):
  ACPI: RISC-V: Add support for RIMT
  ACPI: scan: Add support for RISC-V in acpi_iommu_configure_id()
  iommu/riscv: Add ACPI support

 MAINTAINERS                          |   1 +
 arch/riscv/Kconfig                   |   1 +
 drivers/acpi/Kconfig                 |   4 +
 drivers/acpi/riscv/Kconfig           |   7 +
 drivers/acpi/riscv/Makefile          |   1 +
 drivers/acpi/riscv/init.c            |   2 +
 drivers/acpi/riscv/init.h            |   1 +
 drivers/acpi/riscv/rimt.c            | 523 +++++++++++++++++++++++++++
 drivers/acpi/scan.c                  |   9 +-
 drivers/iommu/riscv/iommu-platform.c |  17 +-
 drivers/iommu/riscv/iommu.c          |  10 +
 include/linux/acpi_rimt.h            |  26 ++
 12 files changed, 599 insertions(+), 3 deletions(-)
 create mode 100644 drivers/acpi/riscv/Kconfig
 create mode 100644 drivers/acpi/riscv/rimt.c
 create mode 100644 include/linux/acpi_rimt.h

-- 
2.43.0

[PATCH v3 1/3] ACPI: RISC-V: Add support for RIMT

[Sunil V L]

RISC-V IO Mapping Table (RIMT) is a static ACPI table to communicate
IOMMU information to the OS. The spec is available at [1].

The changes at high level are,
	a) Initialize data structures required for IOMMU/device
	   configuration using the data from RIMT. Provide APIs required
	   for device configuration.
	b) Provide an API for IOMMU drivers to register the
	   fwnode with RIMT data structures. This API will create a
	   fwnode for PCIe IOMMU.

[1] - https://github.com/riscv-non-isa/riscv-acpi-rimt

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
---
 MAINTAINERS                 |   1 +
 arch/riscv/Kconfig          |   1 +
 drivers/acpi/Kconfig        |   4 +
 drivers/acpi/riscv/Kconfig  |   7 +
 drivers/acpi/riscv/Makefile |   1 +
 drivers/acpi/riscv/init.c   |   2 +
 drivers/acpi/riscv/init.h   |   1 +
 drivers/acpi/riscv/rimt.c   | 523 ++++++++++++++++++++++++++++++++++++
 include/linux/acpi_rimt.h   |  26 ++
 9 files changed, 566 insertions(+)
 create mode 100644 drivers/acpi/riscv/Kconfig
 create mode 100644 drivers/acpi/riscv/rimt.c
 create mode 100644 include/linux/acpi_rimt.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 4bac4ea21b64..c8aac26707af 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -345,6 +345,7 @@ L:	linux-acpi@vger.kernel.org
 L:	linux-riscv@lists.infradead.org
 S:	Maintained
 F:	drivers/acpi/riscv/
+F:	include/linux/acpi_rimt.h
 
 ACPI PCC(Platform Communication Channel) MAILBOX DRIVER
 M:	Sudeep Holla <sudeep.holla@arm.com>
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 36061f4732b7..96d64e0a7b97 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -16,6 +16,7 @@ config RISCV
 	select ACPI_MCFG if (ACPI && PCI)
 	select ACPI_PPTT if ACPI
 	select ACPI_REDUCED_HARDWARE_ONLY if ACPI
+        select ACPI_RIMT if ACPI
 	select ACPI_SPCR_TABLE if ACPI
 	select ARCH_DMA_DEFAULT_COHERENT
 	select ARCH_ENABLE_HUGEPAGE_MIGRATION if HUGETLB_PAGE && MIGRATION
diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index 7bc40c2735ac..4381803c308c 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -546,6 +546,10 @@ if ARM64
 source "drivers/acpi/arm64/Kconfig"
 endif
 
+if RISCV
+source "drivers/acpi/riscv/Kconfig"
+endif
+
 config ACPI_PPTT
 	bool
 
diff --git a/drivers/acpi/riscv/Kconfig b/drivers/acpi/riscv/Kconfig
new file mode 100644
index 000000000000..046296a18d00
--- /dev/null
+++ b/drivers/acpi/riscv/Kconfig
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# ACPI Configuration for RISC-V
+#
+
+config ACPI_RIMT
+	bool
diff --git a/drivers/acpi/riscv/Makefile b/drivers/acpi/riscv/Makefile
index a96fdf1e2cb8..1284a076fa88 100644
--- a/drivers/acpi/riscv/Makefile
+++ b/drivers/acpi/riscv/Makefile
@@ -2,3 +2,4 @@
 obj-y					+= rhct.o init.o irq.o
 obj-$(CONFIG_ACPI_PROCESSOR_IDLE)	+= cpuidle.o
 obj-$(CONFIG_ACPI_CPPC_LIB)		+= cppc.o
+obj-$(CONFIG_ACPI_RIMT)			+= rimt.o
diff --git a/drivers/acpi/riscv/init.c b/drivers/acpi/riscv/init.c
index 673e4d5dd752..7c00f7995e86 100644
--- a/drivers/acpi/riscv/init.c
+++ b/drivers/acpi/riscv/init.c
@@ -10,4 +10,6 @@
 void __init acpi_arch_init(void)
 {
 	riscv_acpi_init_gsi_mapping();
+	if (IS_ENABLED(CONFIG_ACPI_RIMT))
+		riscv_acpi_rimt_init();
 }
diff --git a/drivers/acpi/riscv/init.h b/drivers/acpi/riscv/init.h
index 0b9a07e4031f..1680aa2aaf23 100644
--- a/drivers/acpi/riscv/init.h
+++ b/drivers/acpi/riscv/init.h
@@ -2,3 +2,4 @@
 #include <linux/init.h>
 
 void __init riscv_acpi_init_gsi_mapping(void);
+void __init riscv_acpi_rimt_init(void);
diff --git a/drivers/acpi/riscv/rimt.c b/drivers/acpi/riscv/rimt.c
new file mode 100644
index 000000000000..8cb6f5cf39e2
--- /dev/null
+++ b/drivers/acpi/riscv/rimt.c
@@ -0,0 +1,523 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2024-2025, Ventana Micro Systems Inc
+ *	Author: Sunil V L <sunilvl@ventanamicro.com>
+ *
+ */
+
+#include <linux/acpi.h>
+#include <linux/acpi_rimt.h>
+#include <linux/iommu.h>
+#include <linux/list.h>
+#include <linux/pci.h>
+#include <linux/platform_device.h>
+#include "init.h"
+
+struct rimt_fwnode {
+	struct list_head list;
+	struct acpi_rimt_node *rimt_node;
+	struct fwnode_handle *fwnode;
+};
+
+static LIST_HEAD(rimt_fwnode_list);
+static DEFINE_SPINLOCK(rimt_fwnode_lock);
+
+#define RIMT_TYPE_MASK(type)	(1 << (type))
+#define RIMT_IOMMU_TYPE		BIT(0)
+
+/* Root pointer to the mapped RIMT table */
+static struct acpi_table_header *rimt_table;
+
+/**
+ * rimt_set_fwnode() - Create rimt_fwnode and use it to register
+ *		       iommu data in the rimt_fwnode_list
+ *
+ * @rimt_node: RIMT table node associated with the IOMMU
+ * @fwnode: fwnode associated with the RIMT node
+ *
+ * Returns: 0 on success
+ *          <0 on failure
+ */
+static inline int rimt_set_fwnode(struct acpi_rimt_node *rimt_node,
+				  struct fwnode_handle *fwnode)
+{
+	struct rimt_fwnode *np;
+
+	np = kzalloc(sizeof(*np), GFP_ATOMIC);
+
+	if (WARN_ON(!np))
+		return -ENOMEM;
+
+	INIT_LIST_HEAD(&np->list);
+	np->rimt_node = rimt_node;
+	np->fwnode = fwnode;
+
+	spin_lock(&rimt_fwnode_lock);
+	list_add_tail(&np->list, &rimt_fwnode_list);
+	spin_unlock(&rimt_fwnode_lock);
+
+	return 0;
+}
+
+/**
+ * rimt_get_fwnode() - Retrieve fwnode associated with an RIMT node
+ *
+ * @node: RIMT table node to be looked-up
+ *
+ * Returns: fwnode_handle pointer on success, NULL on failure
+ */
+static inline struct fwnode_handle *rimt_get_fwnode(struct acpi_rimt_node *node)
+{
+	struct rimt_fwnode *curr;
+	struct fwnode_handle *fwnode = NULL;
+
+	spin_lock(&rimt_fwnode_lock);
+	list_for_each_entry(curr, &rimt_fwnode_list, list) {
+		if (curr->rimt_node == node) {
+			fwnode = curr->fwnode;
+			break;
+		}
+	}
+	spin_unlock(&rimt_fwnode_lock);
+
+	return fwnode;
+}
+
+static acpi_status rimt_match_node_callback(struct acpi_rimt_node *node,
+					    void *context)
+{
+	struct device *dev = context;
+	acpi_status status = AE_NOT_FOUND;
+
+	if (node->type == ACPI_RIMT_NODE_TYPE_IOMMU) {
+		struct acpi_rimt_iommu *iommu_node = (struct acpi_rimt_iommu *)&node->node_data;
+
+		if (dev_is_pci(dev)) {
+			struct pci_dev *pdev;
+			u16 bdf;
+
+			pdev = to_pci_dev(dev);
+			bdf = PCI_DEVID(pdev->bus->number, pdev->devfn);
+			if ((pci_domain_nr(pdev->bus) == iommu_node->pcie_segment_number) &&
+			    bdf == iommu_node->pcie_bdf) {
+				status = AE_OK;
+			} else {
+				status = AE_NOT_FOUND;
+			}
+		} else {
+			struct platform_device *pdev = to_platform_device(dev);
+			struct resource *res;
+
+			res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+			if (res && res->start == iommu_node->base_address)
+				status = AE_OK;
+			else
+				status = AE_NOT_FOUND;
+		}
+	} else if (node->type == ACPI_RIMT_NODE_TYPE_PCIE_ROOT_COMPLEX) {
+		struct acpi_rimt_pcie_rc *pci_rc;
+		struct pci_bus *bus;
+
+		bus = to_pci_bus(dev);
+		pci_rc = (struct acpi_rimt_pcie_rc *)node->node_data;
+
+		/*
+		 * It is assumed that PCI segment numbers maps one-to-one
+		 * with root complexes. Each segment number can represent only
+		 * one root complex.
+		 */
+		status = pci_rc->pcie_segment_number == pci_domain_nr(bus) ?
+							AE_OK : AE_NOT_FOUND;
+	} else if (node->type == ACPI_RIMT_NODE_TYPE_PLAT_DEVICE) {
+		struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER, NULL };
+		struct acpi_device *adev;
+		struct acpi_rimt_platform_device *ncomp;
+		struct device *plat_dev = dev;
+
+		/*
+		 * Walk the device tree to find a device with an
+		 * ACPI companion; there is no point in scanning
+		 * RIMT for a device matching a platform device if
+		 * the device does not have an ACPI companion to
+		 * start with.
+		 */
+		do {
+			adev = ACPI_COMPANION(plat_dev);
+			if (adev)
+				break;
+
+			plat_dev = plat_dev->parent;
+		} while (plat_dev);
+
+		if (!adev)
+			return status;
+
+		status = acpi_get_name(adev->handle, ACPI_FULL_PATHNAME, &buf);
+		if (ACPI_FAILURE(status)) {
+			dev_warn(plat_dev, "Can't get device full path name\n");
+			return status;
+		}
+
+		ncomp = (struct acpi_rimt_platform_device *)node->node_data;
+		status = !strcmp(ncomp->device_name, buf.pointer) ?
+							AE_OK : AE_NOT_FOUND;
+		acpi_os_free(buf.pointer);
+	}
+
+	return status;
+}
+
+static struct acpi_rimt_node *rimt_scan_node(enum acpi_rimt_node_type type,
+					     void *context)
+{
+	struct acpi_rimt_node *rimt_node, *rimt_end;
+	struct acpi_table_rimt *rimt;
+	int i;
+
+	if (!rimt_table)
+		return NULL;
+
+	/* Get the first RIMT node */
+	rimt = (struct acpi_table_rimt *)rimt_table;
+	rimt_node = ACPI_ADD_PTR(struct acpi_rimt_node, rimt,
+				 rimt->node_offset);
+	rimt_end = ACPI_ADD_PTR(struct acpi_rimt_node, rimt_table,
+				rimt_table->length);
+
+	for (i = 0; i < rimt->num_nodes; i++) {
+		if (WARN_TAINT(rimt_node >= rimt_end, TAINT_FIRMWARE_WORKAROUND,
+			       "RIMT node pointer overflows, bad table!\n"))
+			return NULL;
+
+		if (rimt_node->type == type &&
+		    ACPI_SUCCESS(rimt_match_node_callback(rimt_node, context)))
+			return rimt_node;
+
+		rimt_node = ACPI_ADD_PTR(struct acpi_rimt_node, rimt_node,
+					 rimt_node->length);
+	}
+
+	return NULL;
+}
+
+static bool rimt_pcie_rc_supports_ats(struct acpi_rimt_node *node)
+{
+	struct acpi_rimt_pcie_rc *pci_rc;
+
+	pci_rc = (struct acpi_rimt_pcie_rc *)node->node_data;
+	return pci_rc->flags & ACPI_RIMT_PCIE_ATS_SUPPORTED;
+}
+
+static int rimt_iommu_xlate(struct device *dev, struct acpi_rimt_node *node, u32 deviceid)
+{
+	struct fwnode_handle *rimt_fwnode;
+
+	if (!node)
+		return -ENODEV;
+
+	rimt_fwnode = rimt_get_fwnode(node);
+
+	/*
+	 * The IOMMU drivers may not be probed yet.
+	 * Defer the IOMMU configuration
+	 */
+	if (!rimt_fwnode)
+		return -EPROBE_DEFER;
+
+	return acpi_iommu_fwspec_init(dev, deviceid, rimt_fwnode);
+}
+
+struct rimt_pci_alias_info {
+	struct device *dev;
+	struct acpi_rimt_node *node;
+	const struct iommu_ops *ops;
+};
+
+static int rimt_id_map(struct acpi_rimt_id_mapping *map, u8 type, u32 rid_in, u32 *rid_out)
+{
+	if (rid_in < map->source_id_base ||
+	    (rid_in > map->source_id_base + map->num_ids))
+		return -ENXIO;
+
+	*rid_out = map->dest_id_base + (rid_in - map->source_id_base);
+	return 0;
+}
+
+static struct acpi_rimt_node *rimt_node_get_id(struct acpi_rimt_node *node,
+					       u32 *id_out, int index)
+{
+	struct acpi_rimt_platform_device *plat_node;
+	struct acpi_rimt_pcie_rc *pci_node;
+	u32 id_mapping_offset, num_id_mapping;
+	struct acpi_rimt_id_mapping *map;
+	struct acpi_rimt_node *parent;
+
+	if (node->type == ACPI_RIMT_NODE_TYPE_PCIE_ROOT_COMPLEX) {
+		pci_node = (struct acpi_rimt_pcie_rc *)&node->node_data;
+		id_mapping_offset = pci_node->id_mapping_offset;
+		num_id_mapping = pci_node->num_id_mappings;
+	} else if (node->type == ACPI_RIMT_NODE_TYPE_PLAT_DEVICE) {
+		plat_node = (struct acpi_rimt_platform_device *)&node->node_data;
+		id_mapping_offset = plat_node->id_mapping_offset;
+		num_id_mapping = plat_node->num_id_mappings;
+	} else {
+		return NULL;
+	}
+
+	if (!id_mapping_offset || !num_id_mapping || index >= num_id_mapping)
+		return NULL;
+
+	map = ACPI_ADD_PTR(struct acpi_rimt_id_mapping, node,
+			   id_mapping_offset + index * sizeof(*map));
+
+	/* Firmware bug! */
+	if (!map->dest_offset) {
+		pr_err(FW_BUG "[node %p type %d] ID map has NULL parent reference\n",
+		       node, node->type);
+		return NULL;
+	}
+
+	parent = ACPI_ADD_PTR(struct acpi_rimt_node, rimt_table, map->dest_offset);
+
+	if (node->type == ACPI_RIMT_NODE_TYPE_PLAT_DEVICE ||
+	    node->type == ACPI_RIMT_NODE_TYPE_PCIE_ROOT_COMPLEX) {
+		*id_out = map->dest_offset;
+		return parent;
+	}
+
+	return NULL;
+}
+
+static struct acpi_rimt_node *rimt_node_map_id(struct acpi_rimt_node *node,
+					       u32 id_in, u32 *id_out,
+					       u8 type_mask)
+{
+	struct acpi_rimt_pcie_rc *pci_node;
+	struct acpi_rimt_platform_device *plat_node;
+	u32 id = id_in;
+	u32 id_mapping_offset, num_id_mapping;
+
+	/* Parse the ID mapping tree to find specified node type */
+	while (node) {
+		struct acpi_rimt_id_mapping *map;
+		int i, rc = 0;
+		u32 map_id = id;
+
+		if (RIMT_TYPE_MASK(node->type) & type_mask) {
+			if (id_out)
+				*id_out = id;
+			return node;
+		}
+
+		if (node->type == ACPI_RIMT_NODE_TYPE_PCIE_ROOT_COMPLEX) {
+			pci_node = (struct acpi_rimt_pcie_rc *)&node->node_data;
+			id_mapping_offset = pci_node->id_mapping_offset;
+			num_id_mapping = pci_node->num_id_mappings;
+		} else if (node->type == ACPI_RIMT_NODE_TYPE_PLAT_DEVICE) {
+			plat_node = (struct acpi_rimt_platform_device *)&node->node_data;
+			id_mapping_offset = plat_node->id_mapping_offset;
+			num_id_mapping = plat_node->num_id_mappings;
+		} else {
+			goto fail_map;
+		}
+
+		if (!id_mapping_offset || !num_id_mapping)
+			goto fail_map;
+
+		map = ACPI_ADD_PTR(struct acpi_rimt_id_mapping, node,
+				   id_mapping_offset);
+
+		/* Firmware bug! */
+		if (!map->dest_offset) {
+			pr_err(FW_BUG "[node %p type %d] ID map has NULL parent reference\n",
+			       node, node->type);
+			goto fail_map;
+		}
+
+		/* Do the ID translation */
+		for (i = 0; i < num_id_mapping; i++, map++) {
+			rc = rimt_id_map(map, node->type, map_id, &id);
+			if (!rc)
+				break;
+		}
+
+		if (i == num_id_mapping)
+			goto fail_map;
+
+		node = ACPI_ADD_PTR(struct acpi_rimt_node, rimt_table,
+				    rc ? 0 : map->dest_offset);
+	}
+
+fail_map:
+	/* Map input ID to output ID unchanged on mapping failure */
+	if (id_out)
+		*id_out = id_in;
+
+	return NULL;
+}
+
+static struct acpi_rimt_node *rimt_node_map_platform_id(struct acpi_rimt_node *node, u32 *id_out,
+							u8 type_mask, int index)
+{
+	struct acpi_rimt_node *parent;
+	u32 id;
+
+	parent = rimt_node_get_id(node, &id, index);
+	if (!parent)
+		return NULL;
+
+	if (!(RIMT_TYPE_MASK(parent->type) & type_mask))
+		parent = rimt_node_map_id(parent, id, id_out, type_mask);
+	else
+		if (id_out)
+			*id_out = id;
+
+	return parent;
+}
+
+static int rimt_pci_iommu_init(struct pci_dev *pdev, u16 alias, void *data)
+{
+	struct rimt_pci_alias_info *info = data;
+	struct acpi_rimt_node *parent;
+	u32 deviceid;
+
+	parent = rimt_node_map_id(info->node, alias, &deviceid, RIMT_IOMMU_TYPE);
+	return rimt_iommu_xlate(info->dev, parent, deviceid);
+}
+
+/*
+ * RISC-V supports IOMMU as a PCI device or a platform device.
+ * When it is a platform device, there should be a namespace device as
+ * well along with RIMT. To create the link between RIMT information and
+ * the platform device, the IOMMU driver should register itself with the
+ * RIMT module. This is true for PCI based IOMMU as well.
+ */
+int rimt_iommu_register(struct device *dev)
+{
+	struct fwnode_handle *rimt_fwnode;
+	struct acpi_rimt_node *node;
+
+	node = rimt_scan_node(ACPI_RIMT_NODE_TYPE_IOMMU, dev);
+	if (!node) {
+		pr_err("Could not find IOMMU node in RIMT\n");
+		return -ENODEV;
+	}
+
+	if (dev_is_pci(dev)) {
+		rimt_fwnode = acpi_alloc_fwnode_static();
+		if (!rimt_fwnode)
+			return -ENOMEM;
+
+		rimt_fwnode->dev = dev;
+		if (!dev->fwnode)
+			dev->fwnode = rimt_fwnode;
+
+		rimt_set_fwnode(node, rimt_fwnode);
+	} else {
+		rimt_set_fwnode(node, dev->fwnode);
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_IOMMU_API
+
+static int rimt_plat_iommu_map(struct device *dev, struct acpi_rimt_node *node)
+{
+	struct acpi_rimt_node *parent;
+	int err = -ENODEV, i = 0;
+	u32 deviceid = 0;
+
+	do {
+		parent = rimt_node_map_platform_id(node, &deviceid,
+						   RIMT_IOMMU_TYPE,
+						   i++);
+
+		if (parent)
+			err = rimt_iommu_xlate(dev, parent, deviceid);
+	} while (parent && !err);
+
+	return err;
+}
+
+static int rimt_plat_iommu_map_id(struct device *dev,
+				  struct acpi_rimt_node *node,
+				  const u32 *in_id)
+{
+	struct acpi_rimt_node *parent;
+	u32 deviceid;
+
+	parent = rimt_node_map_id(node, *in_id, &deviceid, RIMT_IOMMU_TYPE);
+	if (parent)
+		return rimt_iommu_xlate(dev, parent, deviceid);
+
+	return -ENODEV;
+}
+
+/**
+ * rimt_iommu_configure_id - Set-up IOMMU configuration for a device.
+ *
+ * @dev: device to configure
+ * @id_in: optional input id const value pointer
+ *
+ * Returns: 0 on success, <0 on failure
+ */
+int rimt_iommu_configure_id(struct device *dev, const u32 *id_in)
+{
+	struct acpi_rimt_node *node;
+	int err = -ENODEV;
+
+	if (dev_is_pci(dev)) {
+		struct iommu_fwspec *fwspec;
+		struct pci_bus *bus = to_pci_dev(dev)->bus;
+		struct rimt_pci_alias_info info = { .dev = dev };
+
+		node = rimt_scan_node(ACPI_RIMT_NODE_TYPE_PCIE_ROOT_COMPLEX, &bus->dev);
+		if (!node)
+			return -ENODEV;
+
+		info.node = node;
+		err = pci_for_each_dma_alias(to_pci_dev(dev),
+					     rimt_pci_iommu_init, &info);
+
+		fwspec = dev_iommu_fwspec_get(dev);
+		if (fwspec && rimt_pcie_rc_supports_ats(node))
+			fwspec->flags |= IOMMU_FWSPEC_PCI_RC_ATS;
+	} else {
+		node = rimt_scan_node(ACPI_RIMT_NODE_TYPE_PLAT_DEVICE, dev);
+		if (!node)
+			return -ENODEV;
+
+		err = id_in ? rimt_plat_iommu_map_id(dev, node, id_in) :
+			      rimt_plat_iommu_map(dev, node);
+	}
+
+	return err;
+}
+
+#else
+int rimt_iommu_configure_id(struct device *dev, const u32 *id_in)
+{
+	return -ENODEV;
+}
+#endif
+
+void __init riscv_acpi_rimt_init(void)
+{
+	acpi_status status;
+
+	/* rimt_table will be used at runtime after the rimt init,
+	 * so we don't need to call acpi_put_table() to release
+	 * the RIMT table mapping.
+	 */
+	status = acpi_get_table(ACPI_SIG_RIMT, 0, &rimt_table);
+	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;
+	}
+}
diff --git a/include/linux/acpi_rimt.h b/include/linux/acpi_rimt.h
new file mode 100644
index 000000000000..ce4d136d4f81
--- /dev/null
+++ b/include/linux/acpi_rimt.h
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ *  Copyright (C) 2024-2025, Ventana Micro Systems Inc.
+ *	Author: Sunil V L <sunilvl@ventanamicro.com>
+ */
+
+#ifndef _ACPI_RIMT_H
+#define _ACPI_RIMT_H
+
+#ifdef CONFIG_ACPI_RIMT
+int rimt_iommu_configure_id(struct device *dev, const u32 *id_in);
+
+int rimt_iommu_register(struct device *dev);
+#else
+static inline int rimt_iommu_register(struct device *dev)
+{
+	return -ENODEV;
+}
+
+static inline int rimt_iommu_configure_id(struct device *dev, const u32 *id_in)
+{
+	return -ENODEV;
+}
+#endif
+
+#endif /* _ACPI_RIMT_H */
-- 
2.43.0

Re: [PATCH v3 1/3] ACPI: RISC-V: Add support for RIMT

[Andrew Jones]

Hi Sunil,

I found a few nits while skimming this.

On Mon, Jun 30, 2025 at 09:18:01AM +0530, Sunil V L wrote:
> RISC-V IO Mapping Table (RIMT) is a static ACPI table to communicate
> IOMMU information to the OS. The spec is available at [1].
> 
> The changes at high level are,
> 	a) Initialize data structures required for IOMMU/device
> 	   configuration using the data from RIMT. Provide APIs required
> 	   for device configuration.
> 	b) Provide an API for IOMMU drivers to register the
> 	   fwnode with RIMT data structures. This API will create a
> 	   fwnode for PCIe IOMMU.
> 
> [1] - https://github.com/riscv-non-isa/riscv-acpi-rimt
> 
> Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
> ---
>  MAINTAINERS                 |   1 +
>  arch/riscv/Kconfig          |   1 +
>  drivers/acpi/Kconfig        |   4 +
>  drivers/acpi/riscv/Kconfig  |   7 +
>  drivers/acpi/riscv/Makefile |   1 +
>  drivers/acpi/riscv/init.c   |   2 +
>  drivers/acpi/riscv/init.h   |   1 +
>  drivers/acpi/riscv/rimt.c   | 523 ++++++++++++++++++++++++++++++++++++
>  include/linux/acpi_rimt.h   |  26 ++
>  9 files changed, 566 insertions(+)
>  create mode 100644 drivers/acpi/riscv/Kconfig
>  create mode 100644 drivers/acpi/riscv/rimt.c
>  create mode 100644 include/linux/acpi_rimt.h
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 4bac4ea21b64..c8aac26707af 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -345,6 +345,7 @@ L:	linux-acpi@vger.kernel.org
>  L:	linux-riscv@lists.infradead.org
>  S:	Maintained
>  F:	drivers/acpi/riscv/
> +F:	include/linux/acpi_rimt.h
>  
>  ACPI PCC(Platform Communication Channel) MAILBOX DRIVER
>  M:	Sudeep Holla <sudeep.holla@arm.com>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 36061f4732b7..96d64e0a7b97 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -16,6 +16,7 @@ config RISCV
>  	select ACPI_MCFG if (ACPI && PCI)
>  	select ACPI_PPTT if ACPI
>  	select ACPI_REDUCED_HARDWARE_ONLY if ACPI
> +        select ACPI_RIMT if ACPI

Should use tab here.

>  	select ACPI_SPCR_TABLE if ACPI
>  	select ARCH_DMA_DEFAULT_COHERENT
>  	select ARCH_ENABLE_HUGEPAGE_MIGRATION if HUGETLB_PAGE && MIGRATION
> diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
> index 7bc40c2735ac..4381803c308c 100644
> --- a/drivers/acpi/Kconfig
> +++ b/drivers/acpi/Kconfig
> @@ -546,6 +546,10 @@ if ARM64
>  source "drivers/acpi/arm64/Kconfig"
>  endif
>  
> +if RISCV
> +source "drivers/acpi/riscv/Kconfig"
> +endif
> +
>  config ACPI_PPTT
>  	bool
>  
> diff --git a/drivers/acpi/riscv/Kconfig b/drivers/acpi/riscv/Kconfig
> new file mode 100644
> index 000000000000..046296a18d00
> --- /dev/null
> +++ b/drivers/acpi/riscv/Kconfig
> @@ -0,0 +1,7 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +#
> +# ACPI Configuration for RISC-V
> +#
> +
> +config ACPI_RIMT
> +	bool
> diff --git a/drivers/acpi/riscv/Makefile b/drivers/acpi/riscv/Makefile
> index a96fdf1e2cb8..1284a076fa88 100644
> --- a/drivers/acpi/riscv/Makefile
> +++ b/drivers/acpi/riscv/Makefile
> @@ -2,3 +2,4 @@
>  obj-y					+= rhct.o init.o irq.o
>  obj-$(CONFIG_ACPI_PROCESSOR_IDLE)	+= cpuidle.o
>  obj-$(CONFIG_ACPI_CPPC_LIB)		+= cppc.o
> +obj-$(CONFIG_ACPI_RIMT)			+= rimt.o
> diff --git a/drivers/acpi/riscv/init.c b/drivers/acpi/riscv/init.c
> index 673e4d5dd752..7c00f7995e86 100644
> --- a/drivers/acpi/riscv/init.c
> +++ b/drivers/acpi/riscv/init.c
> @@ -10,4 +10,6 @@
>  void __init acpi_arch_init(void)
>  {
>  	riscv_acpi_init_gsi_mapping();
> +	if (IS_ENABLED(CONFIG_ACPI_RIMT))
> +		riscv_acpi_rimt_init();
>  }
> diff --git a/drivers/acpi/riscv/init.h b/drivers/acpi/riscv/init.h
> index 0b9a07e4031f..1680aa2aaf23 100644
> --- a/drivers/acpi/riscv/init.h
> +++ b/drivers/acpi/riscv/init.h
> @@ -2,3 +2,4 @@
>  #include <linux/init.h>
>  
>  void __init riscv_acpi_init_gsi_mapping(void);
> +void __init riscv_acpi_rimt_init(void);
> diff --git a/drivers/acpi/riscv/rimt.c b/drivers/acpi/riscv/rimt.c
> new file mode 100644
> index 000000000000..8cb6f5cf39e2
> --- /dev/null
> +++ b/drivers/acpi/riscv/rimt.c
> @@ -0,0 +1,523 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2024-2025, Ventana Micro Systems Inc
> + *	Author: Sunil V L <sunilvl@ventanamicro.com>
> + *
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/acpi_rimt.h>
> +#include <linux/iommu.h>
> +#include <linux/list.h>
> +#include <linux/pci.h>
> +#include <linux/platform_device.h>
> +#include "init.h"
> +
> +struct rimt_fwnode {
> +	struct list_head list;
> +	struct acpi_rimt_node *rimt_node;
> +	struct fwnode_handle *fwnode;
> +};
> +
> +static LIST_HEAD(rimt_fwnode_list);
> +static DEFINE_SPINLOCK(rimt_fwnode_lock);
> +
> +#define RIMT_TYPE_MASK(type)	(1 << (type))
> +#define RIMT_IOMMU_TYPE		BIT(0)
> +
> +/* Root pointer to the mapped RIMT table */
> +static struct acpi_table_header *rimt_table;
> +
> +/**
> + * rimt_set_fwnode() - Create rimt_fwnode and use it to register
> + *		       iommu data in the rimt_fwnode_list
> + *
> + * @rimt_node: RIMT table node associated with the IOMMU
> + * @fwnode: fwnode associated with the RIMT node
> + *
> + * Returns: 0 on success
> + *          <0 on failure
> + */
> +static inline int rimt_set_fwnode(struct acpi_rimt_node *rimt_node,
> +				  struct fwnode_handle *fwnode)

I see this is a faithful port of arm's iort functions, but using
'inline' in source files is pretty pointless, so we could drop
that.

> +{
> +	struct rimt_fwnode *np;
> +
> +	np = kzalloc(sizeof(*np), GFP_ATOMIC);
> +
> +	if (WARN_ON(!np))
> +		return -ENOMEM;
> +
> +	INIT_LIST_HEAD(&np->list);
> +	np->rimt_node = rimt_node;
> +	np->fwnode = fwnode;
> +
> +	spin_lock(&rimt_fwnode_lock);
> +	list_add_tail(&np->list, &rimt_fwnode_list);
> +	spin_unlock(&rimt_fwnode_lock);
> +
> +	return 0;
> +}
> +
> +/**
> + * rimt_get_fwnode() - Retrieve fwnode associated with an RIMT node
> + *
> + * @node: RIMT table node to be looked-up
> + *
> + * Returns: fwnode_handle pointer on success, NULL on failure
> + */
> +static inline struct fwnode_handle *rimt_get_fwnode(struct acpi_rimt_node *node)
> +{
> +	struct rimt_fwnode *curr;
> +	struct fwnode_handle *fwnode = NULL;
> +
> +	spin_lock(&rimt_fwnode_lock);
> +	list_for_each_entry(curr, &rimt_fwnode_list, list) {
> +		if (curr->rimt_node == node) {
> +			fwnode = curr->fwnode;
> +			break;
> +		}
> +	}
> +	spin_unlock(&rimt_fwnode_lock);
> +
> +	return fwnode;
> +}
> +
> +static acpi_status rimt_match_node_callback(struct acpi_rimt_node *node,
> +					    void *context)
> +{
> +	struct device *dev = context;
> +	acpi_status status = AE_NOT_FOUND;
> +
> +	if (node->type == ACPI_RIMT_NODE_TYPE_IOMMU) {
> +		struct acpi_rimt_iommu *iommu_node = (struct acpi_rimt_iommu *)&node->node_data;
> +
> +		if (dev_is_pci(dev)) {
> +			struct pci_dev *pdev;
> +			u16 bdf;
> +
> +			pdev = to_pci_dev(dev);
> +			bdf = PCI_DEVID(pdev->bus->number, pdev->devfn);
> +			if ((pci_domain_nr(pdev->bus) == iommu_node->pcie_segment_number) &&
> +			    bdf == iommu_node->pcie_bdf) {
> +				status = AE_OK;
> +			} else {
> +				status = AE_NOT_FOUND;
> +			}
> +		} else {
> +			struct platform_device *pdev = to_platform_device(dev);
> +			struct resource *res;
> +
> +			res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +			if (res && res->start == iommu_node->base_address)
> +				status = AE_OK;
> +			else
> +				status = AE_NOT_FOUND;
> +		}
> +	} else if (node->type == ACPI_RIMT_NODE_TYPE_PCIE_ROOT_COMPLEX) {
> +		struct acpi_rimt_pcie_rc *pci_rc;
> +		struct pci_bus *bus;
> +
> +		bus = to_pci_bus(dev);
> +		pci_rc = (struct acpi_rimt_pcie_rc *)node->node_data;
> +
> +		/*
> +		 * It is assumed that PCI segment numbers maps one-to-one
> +		 * with root complexes. Each segment number can represent only
> +		 * one root complex.
> +		 */
> +		status = pci_rc->pcie_segment_number == pci_domain_nr(bus) ?
> +							AE_OK : AE_NOT_FOUND;
> +	} else if (node->type == ACPI_RIMT_NODE_TYPE_PLAT_DEVICE) {
> +		struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER, NULL };
> +		struct acpi_device *adev;
> +		struct acpi_rimt_platform_device *ncomp;
> +		struct device *plat_dev = dev;
> +
> +		/*
> +		 * Walk the device tree to find a device with an
> +		 * ACPI companion; there is no point in scanning
> +		 * RIMT for a device matching a platform device if
> +		 * the device does not have an ACPI companion to
> +		 * start with.
> +		 */
> +		do {
> +			adev = ACPI_COMPANION(plat_dev);
> +			if (adev)
> +				break;
> +
> +			plat_dev = plat_dev->parent;
> +		} while (plat_dev);
> +
> +		if (!adev)
> +			return status;
> +
> +		status = acpi_get_name(adev->handle, ACPI_FULL_PATHNAME, &buf);
> +		if (ACPI_FAILURE(status)) {
> +			dev_warn(plat_dev, "Can't get device full path name\n");
> +			return status;
> +		}
> +
> +		ncomp = (struct acpi_rimt_platform_device *)node->node_data;
> +		status = !strcmp(ncomp->device_name, buf.pointer) ?
> +							AE_OK : AE_NOT_FOUND;
> +		acpi_os_free(buf.pointer);
> +	}
> +
> +	return status;
> +}
> +
> +static struct acpi_rimt_node *rimt_scan_node(enum acpi_rimt_node_type type,
> +					     void *context)
> +{
> +	struct acpi_rimt_node *rimt_node, *rimt_end;
> +	struct acpi_table_rimt *rimt;
> +	int i;
> +
> +	if (!rimt_table)
> +		return NULL;
> +
> +	/* Get the first RIMT node */
> +	rimt = (struct acpi_table_rimt *)rimt_table;
> +	rimt_node = ACPI_ADD_PTR(struct acpi_rimt_node, rimt,
> +				 rimt->node_offset);
> +	rimt_end = ACPI_ADD_PTR(struct acpi_rimt_node, rimt_table,
> +				rimt_table->length);
> +
> +	for (i = 0; i < rimt->num_nodes; i++) {
> +		if (WARN_TAINT(rimt_node >= rimt_end, TAINT_FIRMWARE_WORKAROUND,
> +			       "RIMT node pointer overflows, bad table!\n"))
> +			return NULL;
> +
> +		if (rimt_node->type == type &&
> +		    ACPI_SUCCESS(rimt_match_node_callback(rimt_node, context)))
> +			return rimt_node;
> +
> +		rimt_node = ACPI_ADD_PTR(struct acpi_rimt_node, rimt_node,
> +					 rimt_node->length);
> +	}
> +
> +	return NULL;
> +}
> +
> +static bool rimt_pcie_rc_supports_ats(struct acpi_rimt_node *node)
> +{
> +	struct acpi_rimt_pcie_rc *pci_rc;
> +
> +	pci_rc = (struct acpi_rimt_pcie_rc *)node->node_data;
> +	return pci_rc->flags & ACPI_RIMT_PCIE_ATS_SUPPORTED;
> +}
> +
> +static int rimt_iommu_xlate(struct device *dev, struct acpi_rimt_node *node, u32 deviceid)
> +{
> +	struct fwnode_handle *rimt_fwnode;
> +
> +	if (!node)
> +		return -ENODEV;
> +
> +	rimt_fwnode = rimt_get_fwnode(node);
> +
> +	/*
> +	 * The IOMMU drivers may not be probed yet.
> +	 * Defer the IOMMU configuration
> +	 */
> +	if (!rimt_fwnode)
> +		return -EPROBE_DEFER;
> +
> +	return acpi_iommu_fwspec_init(dev, deviceid, rimt_fwnode);
> +}
> +
> +struct rimt_pci_alias_info {
> +	struct device *dev;
> +	struct acpi_rimt_node *node;
> +	const struct iommu_ops *ops;
> +};
> +
> +static int rimt_id_map(struct acpi_rimt_id_mapping *map, u8 type, u32 rid_in, u32 *rid_out)
> +{
> +	if (rid_in < map->source_id_base ||
> +	    (rid_in > map->source_id_base + map->num_ids))
> +		return -ENXIO;
> +
> +	*rid_out = map->dest_id_base + (rid_in - map->source_id_base);
> +	return 0;
> +}
> +
> +static struct acpi_rimt_node *rimt_node_get_id(struct acpi_rimt_node *node,
> +					       u32 *id_out, int index)
> +{
> +	struct acpi_rimt_platform_device *plat_node;
> +	struct acpi_rimt_pcie_rc *pci_node;
> +	u32 id_mapping_offset, num_id_mapping;
> +	struct acpi_rimt_id_mapping *map;
> +	struct acpi_rimt_node *parent;
> +
> +	if (node->type == ACPI_RIMT_NODE_TYPE_PCIE_ROOT_COMPLEX) {
> +		pci_node = (struct acpi_rimt_pcie_rc *)&node->node_data;
> +		id_mapping_offset = pci_node->id_mapping_offset;
> +		num_id_mapping = pci_node->num_id_mappings;
> +	} else if (node->type == ACPI_RIMT_NODE_TYPE_PLAT_DEVICE) {
> +		plat_node = (struct acpi_rimt_platform_device *)&node->node_data;
> +		id_mapping_offset = plat_node->id_mapping_offset;
> +		num_id_mapping = plat_node->num_id_mappings;
> +	} else {
> +		return NULL;
> +	}
> +
> +	if (!id_mapping_offset || !num_id_mapping || index >= num_id_mapping)
> +		return NULL;
> +
> +	map = ACPI_ADD_PTR(struct acpi_rimt_id_mapping, node,
> +			   id_mapping_offset + index * sizeof(*map));
> +
> +	/* Firmware bug! */
> +	if (!map->dest_offset) {
> +		pr_err(FW_BUG "[node %p type %d] ID map has NULL parent reference\n",
> +		       node, node->type);

Should we have a pr_fmt() definition at the top of this source file for
this pr_err?

> +		return NULL;
> +	}
> +
> +	parent = ACPI_ADD_PTR(struct acpi_rimt_node, rimt_table, map->dest_offset);
> +
> +	if (node->type == ACPI_RIMT_NODE_TYPE_PLAT_DEVICE ||
> +	    node->type == ACPI_RIMT_NODE_TYPE_PCIE_ROOT_COMPLEX) {
> +		*id_out = map->dest_offset;
> +		return parent;
> +	}
> +
> +	return NULL;
> +}
> +
> +static struct acpi_rimt_node *rimt_node_map_id(struct acpi_rimt_node *node,
> +					       u32 id_in, u32 *id_out,
> +					       u8 type_mask)
> +{
> +	struct acpi_rimt_pcie_rc *pci_node;
> +	struct acpi_rimt_platform_device *plat_node;
> +	u32 id = id_in;
> +	u32 id_mapping_offset, num_id_mapping;
> +
> +	/* Parse the ID mapping tree to find specified node type */
> +	while (node) {
> +		struct acpi_rimt_id_mapping *map;
> +		int i, rc = 0;
> +		u32 map_id = id;
> +
> +		if (RIMT_TYPE_MASK(node->type) & type_mask) {
> +			if (id_out)
> +				*id_out = id;
> +			return node;
> +		}
> +
> +		if (node->type == ACPI_RIMT_NODE_TYPE_PCIE_ROOT_COMPLEX) {
> +			pci_node = (struct acpi_rimt_pcie_rc *)&node->node_data;
> +			id_mapping_offset = pci_node->id_mapping_offset;
> +			num_id_mapping = pci_node->num_id_mappings;
> +		} else if (node->type == ACPI_RIMT_NODE_TYPE_PLAT_DEVICE) {
> +			plat_node = (struct acpi_rimt_platform_device *)&node->node_data;
> +			id_mapping_offset = plat_node->id_mapping_offset;
> +			num_id_mapping = plat_node->num_id_mappings;
> +		} else {
> +			goto fail_map;
> +		}
> +
> +		if (!id_mapping_offset || !num_id_mapping)
> +			goto fail_map;
> +
> +		map = ACPI_ADD_PTR(struct acpi_rimt_id_mapping, node,
> +				   id_mapping_offset);
> +
> +		/* Firmware bug! */
> +		if (!map->dest_offset) {
> +			pr_err(FW_BUG "[node %p type %d] ID map has NULL parent reference\n",
> +			       node, node->type);
> +			goto fail_map;
> +		}
> +
> +		/* Do the ID translation */
> +		for (i = 0; i < num_id_mapping; i++, map++) {
> +			rc = rimt_id_map(map, node->type, map_id, &id);
> +			if (!rc)
> +				break;
> +		}
> +
> +		if (i == num_id_mapping)
> +			goto fail_map;
> +
> +		node = ACPI_ADD_PTR(struct acpi_rimt_node, rimt_table,
> +				    rc ? 0 : map->dest_offset);
> +	}
> +
> +fail_map:
> +	/* Map input ID to output ID unchanged on mapping failure */
> +	if (id_out)
> +		*id_out = id_in;
> +
> +	return NULL;
> +}
> +
> +static struct acpi_rimt_node *rimt_node_map_platform_id(struct acpi_rimt_node *node, u32 *id_out,
> +							u8 type_mask, int index)
> +{
> +	struct acpi_rimt_node *parent;
> +	u32 id;
> +
> +	parent = rimt_node_get_id(node, &id, index);
> +	if (!parent)
> +		return NULL;
> +
> +	if (!(RIMT_TYPE_MASK(parent->type) & type_mask))
> +		parent = rimt_node_map_id(parent, id, id_out, type_mask);
> +	else
> +		if (id_out)
> +			*id_out = id;
> +
> +	return parent;
> +}
> +
> +static int rimt_pci_iommu_init(struct pci_dev *pdev, u16 alias, void *data)
> +{
> +	struct rimt_pci_alias_info *info = data;
> +	struct acpi_rimt_node *parent;
> +	u32 deviceid;
> +
> +	parent = rimt_node_map_id(info->node, alias, &deviceid, RIMT_IOMMU_TYPE);
> +	return rimt_iommu_xlate(info->dev, parent, deviceid);
> +}
> +
> +/*
> + * RISC-V supports IOMMU as a PCI device or a platform device.
> + * When it is a platform device, there should be a namespace device as
> + * well along with RIMT. To create the link between RIMT information and
> + * the platform device, the IOMMU driver should register itself with the
> + * RIMT module. This is true for PCI based IOMMU as well.
> + */
> +int rimt_iommu_register(struct device *dev)
> +{
> +	struct fwnode_handle *rimt_fwnode;
> +	struct acpi_rimt_node *node;
> +
> +	node = rimt_scan_node(ACPI_RIMT_NODE_TYPE_IOMMU, dev);
> +	if (!node) {
> +		pr_err("Could not find IOMMU node in RIMT\n");
> +		return -ENODEV;
> +	}
> +
> +	if (dev_is_pci(dev)) {
> +		rimt_fwnode = acpi_alloc_fwnode_static();
> +		if (!rimt_fwnode)
> +			return -ENOMEM;
> +
> +		rimt_fwnode->dev = dev;
> +		if (!dev->fwnode)
> +			dev->fwnode = rimt_fwnode;
> +
> +		rimt_set_fwnode(node, rimt_fwnode);
> +	} else {
> +		rimt_set_fwnode(node, dev->fwnode);
> +	}
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_IOMMU_API
> +
> +static int rimt_plat_iommu_map(struct device *dev, struct acpi_rimt_node *node)
> +{
> +	struct acpi_rimt_node *parent;
> +	int err = -ENODEV, i = 0;
> +	u32 deviceid = 0;
> +
> +	do {
> +		parent = rimt_node_map_platform_id(node, &deviceid,
> +						   RIMT_IOMMU_TYPE,
> +						   i++);
> +
> +		if (parent)
> +			err = rimt_iommu_xlate(dev, parent, deviceid);
> +	} while (parent && !err);
> +
> +	return err;
> +}
> +
> +static int rimt_plat_iommu_map_id(struct device *dev,
> +				  struct acpi_rimt_node *node,
> +				  const u32 *in_id)
> +{
> +	struct acpi_rimt_node *parent;
> +	u32 deviceid;
> +
> +	parent = rimt_node_map_id(node, *in_id, &deviceid, RIMT_IOMMU_TYPE);
> +	if (parent)
> +		return rimt_iommu_xlate(dev, parent, deviceid);
> +
> +	return -ENODEV;
> +}
> +
> +/**
> + * rimt_iommu_configure_id - Set-up IOMMU configuration for a device.
> + *
> + * @dev: device to configure
> + * @id_in: optional input id const value pointer
> + *
> + * Returns: 0 on success, <0 on failure
> + */
> +int rimt_iommu_configure_id(struct device *dev, const u32 *id_in)
> +{
> +	struct acpi_rimt_node *node;
> +	int err = -ENODEV;
> +
> +	if (dev_is_pci(dev)) {
> +		struct iommu_fwspec *fwspec;
> +		struct pci_bus *bus = to_pci_dev(dev)->bus;
> +		struct rimt_pci_alias_info info = { .dev = dev };
> +
> +		node = rimt_scan_node(ACPI_RIMT_NODE_TYPE_PCIE_ROOT_COMPLEX, &bus->dev);
> +		if (!node)
> +			return -ENODEV;
> +
> +		info.node = node;
> +		err = pci_for_each_dma_alias(to_pci_dev(dev),
> +					     rimt_pci_iommu_init, &info);
> +
> +		fwspec = dev_iommu_fwspec_get(dev);
> +		if (fwspec && rimt_pcie_rc_supports_ats(node))
> +			fwspec->flags |= IOMMU_FWSPEC_PCI_RC_ATS;
> +	} else {
> +		node = rimt_scan_node(ACPI_RIMT_NODE_TYPE_PLAT_DEVICE, dev);
> +		if (!node)
> +			return -ENODEV;
> +
> +		err = id_in ? rimt_plat_iommu_map_id(dev, node, id_in) :
> +			      rimt_plat_iommu_map(dev, node);
> +	}
> +
> +	return err;
> +}
> +
> +#else
> +int rimt_iommu_configure_id(struct device *dev, const u32 *id_in)
> +{
> +	return -ENODEV;
> +}

This is unnecessary since we have the stub in the header file.

> +#endif
> +
> +void __init riscv_acpi_rimt_init(void)
> +{
> +	acpi_status status;
> +
> +	/* rimt_table will be used at runtime after the rimt init,
> +	 * so we don't need to call acpi_put_table() to release
> +	 * the RIMT table mapping.
> +	 */
> +	status = acpi_get_table(ACPI_SIG_RIMT, 0, &rimt_table);
> +	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;
> +	}
> +}
> diff --git a/include/linux/acpi_rimt.h b/include/linux/acpi_rimt.h
> new file mode 100644
> index 000000000000..ce4d136d4f81
> --- /dev/null
> +++ b/include/linux/acpi_rimt.h
> @@ -0,0 +1,26 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + *  Copyright (C) 2024-2025, Ventana Micro Systems Inc.
> + *	Author: Sunil V L <sunilvl@ventanamicro.com>
> + */
> +
> +#ifndef _ACPI_RIMT_H
> +#define _ACPI_RIMT_H
> +
> +#ifdef CONFIG_ACPI_RIMT
> +int rimt_iommu_configure_id(struct device *dev, const u32 *id_in);
> +

ubernit: no need for this blank line

> +int rimt_iommu_register(struct device *dev);
> +#else
> +static inline int rimt_iommu_register(struct device *dev)
> +{
> +	return -ENODEV;
> +}
> +
> +static inline int rimt_iommu_configure_id(struct device *dev, const u32 *id_in)
> +{
> +	return -ENODEV;
> +}
> +#endif
> +
> +#endif /* _ACPI_RIMT_H */
> -- 
> 2.43.0
>

Thanks,
drew

Re: [PATCH v3 1/3] ACPI: RISC-V: Add support for RIMT

[Sunil V L]

Hi Drew,

Thank you very much for the review!.

On Mon, Jun 30, 2025 at 09:55:09AM +0200, Andrew Jones wrote:
> Hi Sunil,
> 
> I found a few nits while skimming this.
> 
> On Mon, Jun 30, 2025 at 09:18:01AM +0530, Sunil V L wrote:
> > RISC-V IO Mapping Table (RIMT) is a static ACPI table to communicate
> > IOMMU information to the OS. The spec is available at [1].
> > 
> > The changes at high level are,
> > 	a) Initialize data structures required for IOMMU/device
> > 	   configuration using the data from RIMT. Provide APIs required
> > 	   for device configuration.
> > 	b) Provide an API for IOMMU drivers to register the
> > 	   fwnode with RIMT data structures. This API will create a
> > 	   fwnode for PCIe IOMMU.
> > 
> > [1] - https://github.com/riscv-non-isa/riscv-acpi-rimt
> > 
> > Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
> > ---
> >  MAINTAINERS                 |   1 +
> >  arch/riscv/Kconfig          |   1 +
> >  drivers/acpi/Kconfig        |   4 +
> >  drivers/acpi/riscv/Kconfig  |   7 +
> >  drivers/acpi/riscv/Makefile |   1 +
> >  drivers/acpi/riscv/init.c   |   2 +
> >  drivers/acpi/riscv/init.h   |   1 +
> >  drivers/acpi/riscv/rimt.c   | 523 ++++++++++++++++++++++++++++++++++++
> >  include/linux/acpi_rimt.h   |  26 ++
> >  9 files changed, 566 insertions(+)
> >  create mode 100644 drivers/acpi/riscv/Kconfig
> >  create mode 100644 drivers/acpi/riscv/rimt.c
> >  create mode 100644 include/linux/acpi_rimt.h
> > 
[...]
> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > index 36061f4732b7..96d64e0a7b97 100644
> > --- a/arch/riscv/Kconfig
> > +++ b/arch/riscv/Kconfig
> > @@ -16,6 +16,7 @@ config RISCV
> >  	select ACPI_MCFG if (ACPI && PCI)
> >  	select ACPI_PPTT if ACPI
> >  	select ACPI_REDUCED_HARDWARE_ONLY if ACPI
> > +        select ACPI_RIMT if ACPI
> 
> Should use tab here.
> 
Okay.
> >  	select ACPI_SPCR_TABLE if ACPI
> >  	select ARCH_DMA_DEFAULT_COHERENT
> >  	select ARCH_ENABLE_HUGEPAGE_MIGRATION if HUGETLB_PAGE && MIGRATION
[...]
> > +static inline int rimt_set_fwnode(struct acpi_rimt_node *rimt_node,
> > +				  struct fwnode_handle *fwnode)
> 
> I see this is a faithful port of arm's iort functions, but using
> 'inline' in source files is pretty pointless, so we could drop
> that.
> 
Sure.

> > +{
> > +	struct rimt_fwnode *np;
> > +
> > +	np = kzalloc(sizeof(*np), GFP_ATOMIC);
>
[...]
> > +	map = ACPI_ADD_PTR(struct acpi_rimt_id_mapping, node,
> > +			   id_mapping_offset + index * sizeof(*map));
> > +
> > +	/* Firmware bug! */
> > +	if (!map->dest_offset) {
> > +		pr_err(FW_BUG "[node %p type %d] ID map has NULL parent reference\n",
> > +		       node, node->type);
> 
> Should we have a pr_fmt() definition at the top of this source file for
> this pr_err?
> 
Oh yeah. Will add.

> > +		return NULL;
> > +	}
> > +
>
[...]
> > +	return err;
> > +}
> > +
> > +#else
> > +int rimt_iommu_configure_id(struct device *dev, const u32 *id_in)
> > +{
> > +	return -ENODEV;
> > +}
> 
> This is unnecessary since we have the stub in the header file.
> 
Right.

> > +#endif
> > +
>
[...]
> > +int rimt_iommu_configure_id(struct device *dev, const u32 *id_in);
> > +
> 
> ubernit: no need for this blank line
> 
Sure.

Thanks!
Sunil

[PATCH v3 2/3] ACPI: scan: Add support for RISC-V in acpi_iommu_configure_id()

[Sunil V L]

acpi_iommu_configure_id() currently supports only IORT (ARM) and VIOT.
Add support for RISC-V as well.

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/acpi/scan.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
index fb1fe9f3b1a3..70f57d58fd61 100644
--- a/drivers/acpi/scan.c
+++ b/drivers/acpi/scan.c
@@ -11,6 +11,7 @@
 #include <linux/kernel.h>
 #include <linux/acpi.h>
 #include <linux/acpi_iort.h>
+#include <linux/acpi_rimt.h>
 #include <linux/acpi_viot.h>
 #include <linux/iommu.h>
 #include <linux/signal.h>
@@ -1628,8 +1629,12 @@ static int acpi_iommu_configure_id(struct device *dev, const u32 *id_in)
 	}
 
 	err = iort_iommu_configure_id(dev, id_in);
-	if (err && err != -EPROBE_DEFER)
-		err = viot_iommu_configure(dev);
+	if (err && err != -EPROBE_DEFER) {
+		err = rimt_iommu_configure_id(dev, id_in);
+		if (err && err != -EPROBE_DEFER)
+			err = viot_iommu_configure(dev);
+	}
+
 	mutex_unlock(&iommu_probe_device_lock);
 
 	return err;
-- 
2.43.0

Re: [PATCH v3 2/3] ACPI: scan: Add support for RISC-V in acpi_iommu_configure_id()

[Andrew Jones]

On Mon, Jun 30, 2025 at 09:18:02AM +0530, Sunil V L wrote:
> acpi_iommu_configure_id() currently supports only IORT (ARM) and VIOT.
> Add support for RISC-V as well.
> 
> Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
>  drivers/acpi/scan.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index fb1fe9f3b1a3..70f57d58fd61 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -11,6 +11,7 @@
>  #include <linux/kernel.h>
>  #include <linux/acpi.h>
>  #include <linux/acpi_iort.h>
> +#include <linux/acpi_rimt.h>
>  #include <linux/acpi_viot.h>
>  #include <linux/iommu.h>
>  #include <linux/signal.h>
> @@ -1628,8 +1629,12 @@ static int acpi_iommu_configure_id(struct device *dev, const u32 *id_in)
>  	}
>  
>  	err = iort_iommu_configure_id(dev, id_in);
> -	if (err && err != -EPROBE_DEFER)
> -		err = viot_iommu_configure(dev);
> +	if (err && err != -EPROBE_DEFER) {
> +		err = rimt_iommu_configure_id(dev, id_in);
> +		if (err && err != -EPROBE_DEFER)
> +			err = viot_iommu_configure(dev);
> +	}

This can just be

  err = iort_iommu_configure_id(dev, id_in);
  if (err...
     err = rimt_iommu_configure_id(dev, id_in);
  if (err...
     err = viot_iommu_configure(dev);

Thanks,
drew

> +
>  	mutex_unlock(&iommu_probe_device_lock);
>  
>  	return err;
> -- 
> 2.43.0
> 

Re: [PATCH v3 2/3] ACPI: scan: Add support for RISC-V in acpi_iommu_configure_id()

[Sunil V L]

On Mon, Jun 30, 2025 at 10:02:53AM +0200, Andrew Jones wrote:
> On Mon, Jun 30, 2025 at 09:18:02AM +0530, Sunil V L wrote:
> > acpi_iommu_configure_id() currently supports only IORT (ARM) and VIOT.
> > Add support for RISC-V as well.
> > 
> > Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
> > Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > ---
> >  drivers/acpi/scan.c | 9 +++++++--
> >  1 file changed, 7 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> > index fb1fe9f3b1a3..70f57d58fd61 100644
> > --- a/drivers/acpi/scan.c
> > +++ b/drivers/acpi/scan.c
> > @@ -11,6 +11,7 @@
> >  #include <linux/kernel.h>
> >  #include <linux/acpi.h>
> >  #include <linux/acpi_iort.h>
> > +#include <linux/acpi_rimt.h>
> >  #include <linux/acpi_viot.h>
> >  #include <linux/iommu.h>
> >  #include <linux/signal.h>
> > @@ -1628,8 +1629,12 @@ static int acpi_iommu_configure_id(struct device *dev, const u32 *id_in)
> >  	}
> >  
> >  	err = iort_iommu_configure_id(dev, id_in);
> > -	if (err && err != -EPROBE_DEFER)
> > -		err = viot_iommu_configure(dev);
> > +	if (err && err != -EPROBE_DEFER) {
> > +		err = rimt_iommu_configure_id(dev, id_in);
> > +		if (err && err != -EPROBE_DEFER)
> > +			err = viot_iommu_configure(dev);
> > +	}
> 
> This can just be
> 
>   err = iort_iommu_configure_id(dev, id_in);
>   if (err...
>      err = rimt_iommu_configure_id(dev, id_in);
>   if (err...
>      err = viot_iommu_configure(dev);
> 
> Thanks,
> drew
> 
Sure. Let me update in the next version.

Thanks!
Sunil

[PATCH v3 3/3] iommu/riscv: Add ACPI support

[Sunil V L]

RISC-V IO Mapping Table (RIMT) provides the information about the IOMMU
to the OS in ACPI. Add support for ACPI in RISC-V IOMMU drivers by using
RIMT data.

The changes at high level are,

a) Register the IOMMU with RIMT data structures.
b) Enable probing of platform IOMMU in ACPI way using the ACPIID defined
   for the RISC-V IOMMU in the BRS spec [1]. Configure the MSI domain if
   the platform IOMMU uses MSIs.

[1] - https://github.com/riscv-non-isa/riscv-brs/blob/main/acpi-id.adoc

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
---
 drivers/iommu/riscv/iommu-platform.c | 17 ++++++++++++++++-
 drivers/iommu/riscv/iommu.c          | 10 ++++++++++
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/riscv/iommu-platform.c b/drivers/iommu/riscv/iommu-platform.c
index 725e919b97ef..83a28c83f991 100644
--- a/drivers/iommu/riscv/iommu-platform.c
+++ b/drivers/iommu/riscv/iommu-platform.c
@@ -10,6 +10,8 @@
  *	Tomasz Jeznach <tjeznach@rivosinc.com>
  */
 
+#include <linux/acpi.h>
+#include <linux/irqchip/riscv-imsic.h>
 #include <linux/kernel.h>
 #include <linux/msi.h>
 #include <linux/of_irq.h>
@@ -46,6 +48,7 @@ static int riscv_iommu_platform_probe(struct platform_device *pdev)
 	enum riscv_iommu_igs_settings igs;
 	struct device *dev = &pdev->dev;
 	struct riscv_iommu_device *iommu = NULL;
+	struct irq_domain *msi_domain;
 	struct resource *res = NULL;
 	int vec, ret;
 
@@ -76,8 +79,13 @@ static int riscv_iommu_platform_probe(struct platform_device *pdev)
 	switch (igs) {
 	case RISCV_IOMMU_CAPABILITIES_IGS_BOTH:
 	case RISCV_IOMMU_CAPABILITIES_IGS_MSI:
-		if (is_of_node(dev->fwnode))
+		if (is_of_node(dev_fwnode(dev))) {
 			of_msi_configure(dev, to_of_node(dev->fwnode));
+		} else {
+			msi_domain = irq_find_matching_fwnode(imsic_acpi_get_fwnode(dev),
+							      DOMAIN_BUS_PLATFORM_MSI);
+			dev_set_msi_domain(dev, msi_domain);
+		}
 
 		if (!dev_get_msi_domain(dev)) {
 			dev_warn(dev, "failed to find an MSI domain\n");
@@ -150,6 +158,12 @@ static const struct of_device_id riscv_iommu_of_match[] = {
 	{},
 };
 
+static const struct acpi_device_id riscv_iommu_acpi_match[] = {
+	{ "RSCV0004", 0 },
+	{}
+};
+MODULE_DEVICE_TABLE(acpi, riscv_iommu_acpi_match);
+
 static struct platform_driver riscv_iommu_platform_driver = {
 	.probe = riscv_iommu_platform_probe,
 	.remove = riscv_iommu_platform_remove,
@@ -158,6 +172,7 @@ static struct platform_driver riscv_iommu_platform_driver = {
 		.name = "riscv,iommu",
 		.of_match_table = riscv_iommu_of_match,
 		.suppress_bind_attrs = true,
+		.acpi_match_table = riscv_iommu_acpi_match,
 	},
 };
 
diff --git a/drivers/iommu/riscv/iommu.c b/drivers/iommu/riscv/iommu.c
index bb57092ca901..45a263c9e0d5 100644
--- a/drivers/iommu/riscv/iommu.c
+++ b/drivers/iommu/riscv/iommu.c
@@ -12,6 +12,8 @@
 
 #define pr_fmt(fmt) "riscv-iommu: " fmt
 
+#include <linux/acpi.h>
+#include <linux/acpi_rimt.h>
 #include <linux/compiler.h>
 #include <linux/crash_dump.h>
 #include <linux/init.h>
@@ -1651,6 +1653,14 @@ int riscv_iommu_init(struct riscv_iommu_device *iommu)
 		goto err_iodir_off;
 	}
 
+	if (!acpi_disabled) {
+		rc = rimt_iommu_register(iommu->dev);
+		if (rc) {
+			dev_err_probe(iommu->dev, rc, "cannot register iommu with RIMT\n");
+			goto err_remove_sysfs;
+		}
+	}
+
 	rc = iommu_device_register(&iommu->iommu, &riscv_iommu_ops, iommu->dev);
 	if (rc) {
 		dev_err_probe(iommu->dev, rc, "cannot register iommu interface\n");
-- 
2.43.0

Re: [PATCH v3 3/3] iommu/riscv: Add ACPI support

[Andrew Jones]

On Mon, Jun 30, 2025 at 09:18:03AM +0530, Sunil V L wrote:
> RISC-V IO Mapping Table (RIMT) provides the information about the IOMMU
> to the OS in ACPI. Add support for ACPI in RISC-V IOMMU drivers by using
> RIMT data.
> 
> The changes at high level are,
> 
> a) Register the IOMMU with RIMT data structures.
> b) Enable probing of platform IOMMU in ACPI way using the ACPIID defined
>    for the RISC-V IOMMU in the BRS spec [1]. Configure the MSI domain if
>    the platform IOMMU uses MSIs.
> 
> [1] - https://github.com/riscv-non-isa/riscv-brs/blob/main/acpi-id.adoc
> 
> Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
> ---
>  drivers/iommu/riscv/iommu-platform.c | 17 ++++++++++++++++-
>  drivers/iommu/riscv/iommu.c          | 10 ++++++++++
>  2 files changed, 26 insertions(+), 1 deletion(-)
>

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>

Re: [PATCH v3 3/3] iommu/riscv: Add ACPI support

[Will Deacon]

On Mon, Jun 30, 2025 at 09:18:03AM +0530, Sunil V L wrote:
> RISC-V IO Mapping Table (RIMT) provides the information about the IOMMU
> to the OS in ACPI. Add support for ACPI in RISC-V IOMMU drivers by using
> RIMT data.
> 
> The changes at high level are,
> 
> a) Register the IOMMU with RIMT data structures.
> b) Enable probing of platform IOMMU in ACPI way using the ACPIID defined
>    for the RISC-V IOMMU in the BRS spec [1]. Configure the MSI domain if
>    the platform IOMMU uses MSIs.
> 
> [1] - https://github.com/riscv-non-isa/riscv-brs/blob/main/acpi-id.adoc
> 
> Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
> ---
>  drivers/iommu/riscv/iommu-platform.c | 17 ++++++++++++++++-
>  drivers/iommu/riscv/iommu.c          | 10 ++++++++++
>  2 files changed, 26 insertions(+), 1 deletion(-)

This looks relatively straightforward from the IOMMU perspective
(assuming the driver still compiles if CONFIG_ACPI=n) but the ACPI parts
in the first two patches need reviewing before this can land.

Will

Re: [PATCH v3 0/3] RISC-V: Add ACPI support for IOMMU

[Sunil V L]

Hi Tomasz,

Could you please help reviewing this series?

Thanks!
Sunil
On Mon, Jun 30, 2025 at 09:18:00AM +0530, Sunil V L wrote:
> This series adds support for RISC-V IOMMU on ACPI based platforms.
> RISC-V IO Mapping Table (RIMT) is a new static ACPI table [1] introduced
> to communicate IOMMU information to the OS.
> 
> [1] - https://github.com/riscv-non-isa/riscv-acpi-rimt/releases/download/v1.0/rimt-spec.pdf
> 
> Changes since v2:
> 	1) Rebased to 6.16-rc4
> 	2) Removed Anup's SOB and link tags added by mistake in v2.
> 
> Changes since v1:
> 	1) Rebased to v6.16-rc1.
> 	2) Dropped ACPICA patch since it is already available in 6.16-rc1.
> 	3) Added Rafael's ACK.
> 	4) Fixed few issues found by bots.
> 
> 
> Sunil V L (3):
>   ACPI: RISC-V: Add support for RIMT
>   ACPI: scan: Add support for RISC-V in acpi_iommu_configure_id()
>   iommu/riscv: Add ACPI support
> 
>  MAINTAINERS                          |   1 +
>  arch/riscv/Kconfig                   |   1 +
>  drivers/acpi/Kconfig                 |   4 +
>  drivers/acpi/riscv/Kconfig           |   7 +
>  drivers/acpi/riscv/Makefile          |   1 +
>  drivers/acpi/riscv/init.c            |   2 +
>  drivers/acpi/riscv/init.h            |   1 +
>  drivers/acpi/riscv/rimt.c            | 523 +++++++++++++++++++++++++++
>  drivers/acpi/scan.c                  |   9 +-
>  drivers/iommu/riscv/iommu-platform.c |  17 +-
>  drivers/iommu/riscv/iommu.c          |  10 +
>  include/linux/acpi_rimt.h            |  26 ++
>  12 files changed, 599 insertions(+), 3 deletions(-)
>  create mode 100644 drivers/acpi/riscv/Kconfig
>  create mode 100644 drivers/acpi/riscv/rimt.c
>  create mode 100644 include/linux/acpi_rimt.h
> 
> -- 
> 2.43.0
>