[PATCH v5 0/3] of: parsing of multi #{iommu,msi}-cells in maps

[PATCH v5 0/3] of: parsing of multi #{iommu,msi}-cells in maps

[Vijayanand Jitta]

So far our parsing of {iommu,msi}-map properites has always blindly
assumed that the output specifiers will always have exactly 1 cell.
This typically does happen to be the case, but is not actually enforced
(and the PCI msi-map binding even explicitly states support for 0 or 1
cells) - as a result we've now ended up with dodgy DTs out in the field
which depend on this behaviour to map a 1-cell specifier for a 2-cell
provider, despite that being bogus per the bindings themselves.

Since there is some potential use[1] in being able to map at least
single input IDs to multi-cell output specifiers (and properly support
0-cell outputs as well), add support for properly parsing and using the
target nodes' #cells values, albeit with the unfortunate complication of
still having to work around expectations of the old behaviour too.
							-- Robin.

Unlike single #{}-cell, it is complex to establish a linear relation
between input 'id' and output specifier for multi-cell properties, thus
it is always expected that len never going to be > 1. 

The motivation for this patchset originates from the multi-map use case
described in V1, which will be addressed in a subsequent series once the
current fixes for iommu-cell handling are concluded.

These changes have been tested on QEMU for the arm64 architecture. We
plan to perform more extensive testing based on community feedback.

[1] https://lore.kernel.org/all/20250627-video_cb-v3-0-51e18c0ffbce@quicinc.com/

V5:
  Fixed Build Warnings.
  Raised PR for iommu-map dtschema:
  https://github.com/devicetree-org/dt-schema/pull/184

  Link to V4:
  https://lore.kernel.org/all/20251231114257.2382820-1-vijayanand.jitta@oss.qualcomm.com/

V4:
  1) Added Reviewed-by tag.
  2) Resolved warnings reported by kernel test bot, minor code
  reorganization.

  Link to V3:
  https://lore.kernel.org/all/20251221213602.2413124-1-vijayanand.jitta@oss.qualcomm.com/

V3:
  1) Added Reviewed-by tag.
  2) Updated of_map_id_args struct as a wrapper to of_phandle_args and
  added comment description as suggested by Rob Herring.

  Link to V2:
  https://lore.kernel.org/all/20251204095530.8627-1-vijayanand.jitta@oss.qualcomm.com/

V2:
  1) Incorporated the patches from Robin that does the clean implementation.
  2) Dropped the patches the were adding multi-map support from this series
  as suggested.

V1:
 https://lore.kernel.org/all/cover.1762235099.git.charan.kalla@oss.qualcomm.com/

RFC:
 https://lore.kernel.org/all/20250928171718.436440-1-charan.kalla@oss.qualcomm.com/#r

Charan Teja Kalla (1):
  of: factor arguments passed to of_map_id() into a struct

Robin Murphy (2):
  of: Add convenience wrappers for of_map_id()
  of: Respect #{iommu,msi}-cells in maps

 drivers/cdx/cdx_msi.c                    |   5 +-
 drivers/iommu/of_iommu.c                 |  12 +-
 drivers/irqchip/irq-gic-its-msi-parent.c |   2 +-
 drivers/of/base.c                        | 146 +++++++++++++++++------
 drivers/of/irq.c                         |   3 +-
 drivers/pci/controller/dwc/pci-imx6.c    |  14 ++-
 drivers/pci/controller/pcie-apple.c      |   5 +-
 drivers/xen/grant-dma-ops.c              |  21 ++--
 include/linux/of.h                       |  44 ++++++-
 9 files changed, 179 insertions(+), 73 deletions(-)

-- 
2.34.1

[PATCH v5 1/3] of: Add convenience wrappers for of_map_id()

[Vijayanand Jitta]

From: Robin Murphy <robin.murphy@arm.com>

Since we now have quite a few users parsing "iommu-map" and "msi-map"
properties, give them some wrappers to conveniently encapsulate the
appropriate sets of property names. This will also make it easier to
then change of_map_id() to correctly account for specifier cells.

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
---
 drivers/cdx/cdx_msi.c                    |  3 +--
 drivers/iommu/of_iommu.c                 |  4 +---
 drivers/irqchip/irq-gic-its-msi-parent.c |  2 +-
 drivers/of/irq.c                         |  3 +--
 drivers/pci/controller/dwc/pci-imx6.c    |  6 ++----
 drivers/pci/controller/pcie-apple.c      |  3 +--
 drivers/xen/grant-dma-ops.c              |  3 +--
 include/linux/of.h                       | 14 ++++++++++++++
 8 files changed, 22 insertions(+), 16 deletions(-)

diff --git a/drivers/cdx/cdx_msi.c b/drivers/cdx/cdx_msi.c
index 91b95422b263..63b3544ec997 100644
--- a/drivers/cdx/cdx_msi.c
+++ b/drivers/cdx/cdx_msi.c
@@ -128,8 +128,7 @@ static int cdx_msi_prepare(struct irq_domain *msi_domain,
 	int ret;
 
 	/* Retrieve device ID from requestor ID using parent device */
-	ret = of_map_id(parent->of_node, cdx_dev->msi_dev_id, "msi-map", "msi-map-mask",
-			NULL, &dev_id);
+	ret = of_map_msi_id(parent->of_node, cdx_dev->msi_dev_id, NULL, &dev_id);
 	if (ret) {
 		dev_err(dev, "of_map_id failed for MSI: %d\n", ret);
 		return ret;
diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
index 6b989a62def2..a511ecf21fcd 100644
--- a/drivers/iommu/of_iommu.c
+++ b/drivers/iommu/of_iommu.c
@@ -48,9 +48,7 @@ static int of_iommu_configure_dev_id(struct device_node *master_np,
 	struct of_phandle_args iommu_spec = { .args_count = 1 };
 	int err;
 
-	err = of_map_id(master_np, *id, "iommu-map",
-			 "iommu-map-mask", &iommu_spec.np,
-			 iommu_spec.args);
+	err = of_map_iommu_id(master_np, *id, &iommu_spec.np, iommu_spec.args);
 	if (err)
 		return err;
 
diff --git a/drivers/irqchip/irq-gic-its-msi-parent.c b/drivers/irqchip/irq-gic-its-msi-parent.c
index 12f45228c867..d5d8fa65c24d 100644
--- a/drivers/irqchip/irq-gic-its-msi-parent.c
+++ b/drivers/irqchip/irq-gic-its-msi-parent.c
@@ -173,7 +173,7 @@ static int of_pmsi_get_msi_info(struct irq_domain *domain, struct device *dev, u
 
 	struct device_node *msi_ctrl __free(device_node) = NULL;
 
-	return of_map_id(dev->of_node, dev->id, "msi-map", "msi-map-mask", &msi_ctrl, dev_id);
+	return of_map_msi_id(dev->of_node, dev->id, &msi_ctrl, dev_id);
 }
 
 int __weak iort_pmsi_get_dev_id(struct device *dev, u32 *dev_id)
diff --git a/drivers/of/irq.c b/drivers/of/irq.c
index e3816819dbfe..fb50ccb50cfd 100644
--- a/drivers/of/irq.c
+++ b/drivers/of/irq.c
@@ -747,8 +747,7 @@ u32 of_msi_xlate(struct device *dev, struct device_node **msi_np, u32 id_in)
 	 * "msi-map" or an "msi-parent" property.
 	 */
 	for (parent_dev = dev; parent_dev; parent_dev = parent_dev->parent) {
-		if (!of_map_id(parent_dev->of_node, id_in, "msi-map",
-				"msi-map-mask", msi_np, &id_out))
+		if (!of_map_msi_id(parent_dev->of_node, id_in, msi_np, &id_out))
 			break;
 		if (!of_check_msi_parent(parent_dev->of_node, msi_np))
 			break;
diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index 1d8677d7de04..c3e5cb3cb846 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -1143,8 +1143,7 @@ static int imx_pcie_add_lut_by_rid(struct imx_pcie *imx_pcie, u32 rid)
 	u32 sid = 0;
 
 	target = NULL;
-	err_i = of_map_id(dev->of_node, rid, "iommu-map", "iommu-map-mask",
-			  &target, &sid_i);
+	err_i = of_map_iommu_id(dev->of_node, rid, &target, &sid_i);
 	if (target) {
 		of_node_put(target);
 	} else {
@@ -1157,8 +1156,7 @@ static int imx_pcie_add_lut_by_rid(struct imx_pcie *imx_pcie, u32 rid)
 	}
 
 	target = NULL;
-	err_m = of_map_id(dev->of_node, rid, "msi-map", "msi-map-mask",
-			  &target, &sid_m);
+	err_m = of_map_msi_id(dev->of_node, rid, &target, &sid_m);
 
 	/*
 	 *   err_m      target
diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c
index 2d92fc79f6dd..a0937b7b3c4d 100644
--- a/drivers/pci/controller/pcie-apple.c
+++ b/drivers/pci/controller/pcie-apple.c
@@ -764,8 +764,7 @@ static int apple_pcie_enable_device(struct pci_host_bridge *bridge, struct pci_d
 	dev_dbg(&pdev->dev, "added to bus %s, index %d\n",
 		pci_name(pdev->bus->self), port->idx);
 
-	err = of_map_id(port->pcie->dev->of_node, rid, "iommu-map",
-			"iommu-map-mask", NULL, &sid);
+	err = of_map_iommu_id(port->pcie->dev->of_node, rid, NULL, &sid);
 	if (err)
 		return err;
 
diff --git a/drivers/xen/grant-dma-ops.c b/drivers/xen/grant-dma-ops.c
index c2603e700178..1b7696b2d762 100644
--- a/drivers/xen/grant-dma-ops.c
+++ b/drivers/xen/grant-dma-ops.c
@@ -325,8 +325,7 @@ static int xen_dt_grant_init_backend_domid(struct device *dev,
 		struct pci_dev *pdev = to_pci_dev(dev);
 		u32 rid = PCI_DEVID(pdev->bus->number, pdev->devfn);
 
-		if (of_map_id(np, rid, "iommu-map", "iommu-map-mask", &iommu_spec.np,
-				iommu_spec.args)) {
+		if (of_map_iommu_id(np, rid, &iommu_spec.np, iommu_spec.args)) {
 			dev_dbg(dev, "Cannot translate ID\n");
 			return -ESRCH;
 		}
diff --git a/include/linux/of.h b/include/linux/of.h
index 9bbdcf25a2b4..309c5681744b 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -1457,6 +1457,20 @@ static inline int of_property_read_s32(const struct device_node *np,
 	return of_property_read_u32(np, propname, (u32*) out_value);
 }
 
+static inline int of_map_iommu_id(const struct device_node *np, u32 id,
+				  struct device_node **target, u32 *id_out)
+{
+	return of_map_id(np, id, "iommu-map", "iommu-map-mask",
+			 target, id_out);
+}
+
+static inline int of_map_msi_id(const struct device_node *np, u32 id,
+				struct device_node **target, u32 *id_out)
+{
+	return of_map_id(np, id, "msi-map", "msi-map-mask",
+			 target, id_out);
+}
+
 #define of_for_each_phandle(it, err, np, ln, cn, cc)			\
 	for (of_phandle_iterator_init((it), (np), (ln), (cn), (cc)),	\
 	     err = of_phandle_iterator_next(it);			\
-- 
2.34.1

[PATCH v5 2/3] of: factor arguments passed to of_map_id() into a struct

[Vijayanand Jitta]

From: Charan Teja Kalla <charan.kalla@oss.qualcomm.com>

Introduce a new struct type where the optional arguments passed to
of_map_id() are Currently embedded as of_phandle_args struct.
Subsequent patches add additional arguments to the struct that the
caller expects to be filled of_map_id().

Suggested-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Charan Teja Kalla <charan.kalla@oss.qualcomm.com>
Signed-off-by: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
---
 drivers/cdx/cdx_msi.c                 |  2 +-
 drivers/iommu/of_iommu.c              | 12 ++++++---
 drivers/of/base.c                     | 37 +++++++++++++--------------
 drivers/pci/controller/dwc/pci-imx6.c | 10 ++++++--
 drivers/pci/controller/pcie-apple.c   |  4 ++-
 drivers/xen/grant-dma-ops.c           | 20 +++++++++------
 include/linux/of.h                    | 32 ++++++++++++++++++-----
 7 files changed, 75 insertions(+), 42 deletions(-)

diff --git a/drivers/cdx/cdx_msi.c b/drivers/cdx/cdx_msi.c
index 63b3544ec997..7ed9643f1815 100644
--- a/drivers/cdx/cdx_msi.c
+++ b/drivers/cdx/cdx_msi.c
@@ -124,7 +124,7 @@ static int cdx_msi_prepare(struct irq_domain *msi_domain,
 	struct cdx_device *cdx_dev = to_cdx_device(dev);
 	struct device *parent = cdx_dev->cdx->dev;
 	struct msi_domain_info *msi_info;
-	u32 dev_id;
+	u32 dev_id = 0;
 	int ret;
 
 	/* Retrieve device ID from requestor ID using parent device */
diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
index a511ecf21fcd..646ac5a67475 100644
--- a/drivers/iommu/of_iommu.c
+++ b/drivers/iommu/of_iommu.c
@@ -45,15 +45,19 @@ static int of_iommu_configure_dev_id(struct device_node *master_np,
 				     struct device *dev,
 				     const u32 *id)
 {
-	struct of_phandle_args iommu_spec = { .args_count = 1 };
+	struct of_map_id_arg arg = {
+		.map_args = {
+			.args_count = 1,
+		},
+	};
 	int err;
 
-	err = of_map_iommu_id(master_np, *id, &iommu_spec.np, iommu_spec.args);
+	err = of_map_iommu_id(master_np, *id, &arg);
 	if (err)
 		return err;
 
-	err = of_iommu_xlate(dev, &iommu_spec);
-	of_node_put(iommu_spec.np);
+	err = of_iommu_xlate(dev, &arg.map_args);
+	of_node_put(arg.map_args.np);
 	return err;
 }
 
diff --git a/drivers/of/base.c b/drivers/of/base.c
index 0b65039ece53..0c379fa051fe 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -2098,8 +2098,11 @@ int of_find_last_cache_level(unsigned int cpu)
  * @id: device ID to map.
  * @map_name: property name of the map to use.
  * @map_mask_name: optional property name of the mask to use.
- * @target: optional pointer to a target device node.
- * @id_out: optional pointer to receive the translated ID.
+ * @arg: contains the optional params, wrapped in a struct of_phandle_args,
+ *	which includes:
+ *	np: pointer to the target device node
+ *	args_count: number of arguments
+ *	args[]: array to receive the translated ID(s).
  *
  * Given a device ID, look up the appropriate implementation-defined
  * platform ID and/or the target device which receives transactions on that
@@ -2113,21 +2116,21 @@ int of_find_last_cache_level(unsigned int cpu)
  */
 int of_map_id(const struct device_node *np, u32 id,
 	       const char *map_name, const char *map_mask_name,
-	       struct device_node **target, u32 *id_out)
+	       struct of_map_id_arg *arg)
 {
 	u32 map_mask, masked_id;
 	int map_len;
 	const __be32 *map = NULL;
 
-	if (!np || !map_name || (!target && !id_out))
+	if (!np || !map_name || !arg)
 		return -EINVAL;
 
 	map = of_get_property(np, map_name, &map_len);
 	if (!map) {
-		if (target)
+		if (arg->map_args.np)
 			return -ENODEV;
 		/* Otherwise, no map implies no translation */
-		*id_out = id;
+		arg->map_args.args[0] = id;
 		return 0;
 	}
 
@@ -2169,18 +2172,15 @@ int of_map_id(const struct device_node *np, u32 id,
 		if (!phandle_node)
 			return -ENODEV;
 
-		if (target) {
-			if (*target)
-				of_node_put(phandle_node);
-			else
-				*target = phandle_node;
+		if (arg->map_args.np)
+			of_node_put(phandle_node);
+		else
+			arg->map_args.np = phandle_node;
 
-			if (*target != phandle_node)
-				continue;
-		}
+		if (arg->map_args.np != phandle_node)
+			continue;
 
-		if (id_out)
-			*id_out = masked_id - id_base + out_base;
+		arg->map_args.args[0] = masked_id - id_base + out_base;
 
 		pr_debug("%pOF: %s, using mask %08x, id-base: %08x, out-base: %08x, length: %08x, id: %08x -> %08x\n",
 			np, map_name, map_mask, id_base, out_base,
@@ -2189,11 +2189,10 @@ int of_map_id(const struct device_node *np, u32 id,
 	}
 
 	pr_info("%pOF: no %s translation for id 0x%x on %pOF\n", np, map_name,
-		id, target && *target ? *target : NULL);
+		id, arg->map_args.np  ? arg->map_args.np : NULL);
 
 	/* Bypasses translation */
-	if (id_out)
-		*id_out = id;
+	arg->map_args.args[0] = id;
 	return 0;
 }
 EXPORT_SYMBOL_GPL(of_map_id);
diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index c3e5cb3cb846..641f9d34f7a9 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -1138,12 +1138,18 @@ static int imx_pcie_add_lut_by_rid(struct imx_pcie *imx_pcie, u32 rid)
 {
 	struct device *dev = imx_pcie->pci->dev;
 	struct device_node *target;
-	u32 sid_i, sid_m;
+	struct of_map_id_arg arg = {};
+	u32 sid_i, sid_m = 0;
 	int err_i, err_m;
 	u32 sid = 0;
 
 	target = NULL;
-	err_i = of_map_iommu_id(dev->of_node, rid, &target, &sid_i);
+
+	err_i = of_map_iommu_id(dev->of_node, rid, &arg);
+	if (!err_i) {
+		target = arg.map_args.np;
+		sid_i = arg.map_args.args[0];
+	}
 	if (target) {
 		of_node_put(target);
 	} else {
diff --git a/drivers/pci/controller/pcie-apple.c b/drivers/pci/controller/pcie-apple.c
index a0937b7b3c4d..2df15fe075fa 100644
--- a/drivers/pci/controller/pcie-apple.c
+++ b/drivers/pci/controller/pcie-apple.c
@@ -755,6 +755,7 @@ static int apple_pcie_enable_device(struct pci_host_bridge *bridge, struct pci_d
 {
 	u32 sid, rid = pci_dev_id(pdev);
 	struct apple_pcie_port *port;
+	struct of_map_id_arg arg = {};
 	int idx, err;
 
 	port = apple_pcie_get_port(pdev);
@@ -764,10 +765,11 @@ static int apple_pcie_enable_device(struct pci_host_bridge *bridge, struct pci_d
 	dev_dbg(&pdev->dev, "added to bus %s, index %d\n",
 		pci_name(pdev->bus->self), port->idx);
 
-	err = of_map_iommu_id(port->pcie->dev->of_node, rid, NULL, &sid);
+	err = of_map_iommu_id(port->pcie->dev->of_node, rid, &arg);
 	if (err)
 		return err;
 
+	sid = arg.map_args.args[0];
 	mutex_lock(&port->pcie->lock);
 
 	idx = bitmap_find_free_region(port->sid_map, port->sid_map_sz, 0);
diff --git a/drivers/xen/grant-dma-ops.c b/drivers/xen/grant-dma-ops.c
index 1b7696b2d762..8c332b7ff148 100644
--- a/drivers/xen/grant-dma-ops.c
+++ b/drivers/xen/grant-dma-ops.c
@@ -319,38 +319,42 @@ static int xen_dt_grant_init_backend_domid(struct device *dev,
 					   struct device_node *np,
 					   domid_t *backend_domid)
 {
-	struct of_phandle_args iommu_spec = { .args_count = 1 };
+	struct of_map_id_arg arg = {
+		.map_args = {
+			.args_count = 1,
+		},
+	};
 
 	if (dev_is_pci(dev)) {
 		struct pci_dev *pdev = to_pci_dev(dev);
 		u32 rid = PCI_DEVID(pdev->bus->number, pdev->devfn);
 
-		if (of_map_iommu_id(np, rid, &iommu_spec.np, iommu_spec.args)) {
+		if (of_map_iommu_id(np, rid, &arg)) {
 			dev_dbg(dev, "Cannot translate ID\n");
 			return -ESRCH;
 		}
 	} else {
 		if (of_parse_phandle_with_args(np, "iommus", "#iommu-cells",
-				0, &iommu_spec)) {
+				0, &arg.map_args)) {
 			dev_dbg(dev, "Cannot parse iommus property\n");
 			return -ESRCH;
 		}
 	}
 
-	if (!of_device_is_compatible(iommu_spec.np, "xen,grant-dma") ||
-			iommu_spec.args_count != 1) {
+	if (!of_device_is_compatible(arg.map_args.np, "xen,grant-dma") ||
+	    arg.map_args.args_count != 1) {
 		dev_dbg(dev, "Incompatible IOMMU node\n");
-		of_node_put(iommu_spec.np);
+		of_node_put(arg.map_args.np);
 		return -ESRCH;
 	}
 
-	of_node_put(iommu_spec.np);
+	of_node_put(arg.map_args.np);
 
 	/*
 	 * The endpoint ID here means the ID of the domain where the
 	 * corresponding backend is running
 	 */
-	*backend_domid = iommu_spec.args[0];
+	*backend_domid = arg.map_args.args[0];
 
 	return 0;
 }
diff --git a/include/linux/of.h b/include/linux/of.h
index 309c5681744b..514f4f018f99 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -74,6 +74,10 @@ struct of_phandle_args {
 	uint32_t args[MAX_PHANDLE_ARGS];
 };
 
+struct of_map_id_arg {
+	struct of_phandle_args map_args;
+};
+
 struct of_phandle_iterator {
 	/* Common iterator information */
 	const char *cells_name;
@@ -463,7 +467,7 @@ bool of_console_check(const struct device_node *dn, char *name, int index);
 
 int of_map_id(const struct device_node *np, u32 id,
 	       const char *map_name, const char *map_mask_name,
-	       struct device_node **target, u32 *id_out);
+	       struct of_map_id_arg *arg);
 
 phys_addr_t of_dma_get_max_cpu_address(struct device_node *np);
 
@@ -929,7 +933,7 @@ static inline void of_property_clear_flag(struct property *p, unsigned long flag
 
 static inline int of_map_id(const struct device_node *np, u32 id,
 			     const char *map_name, const char *map_mask_name,
-			     struct device_node **target, u32 *id_out)
+			     struct of_map_id_arg *arg)
 {
 	return -EINVAL;
 }
@@ -1458,17 +1462,31 @@ static inline int of_property_read_s32(const struct device_node *np,
 }
 
 static inline int of_map_iommu_id(const struct device_node *np, u32 id,
-				  struct device_node **target, u32 *id_out)
+				  struct of_map_id_arg *arg)
 {
-	return of_map_id(np, id, "iommu-map", "iommu-map-mask",
-			 target, id_out);
+	return of_map_id(np, id, "iommu-map", "iommu-map-mask", arg);
 }
 
 static inline int of_map_msi_id(const struct device_node *np, u32 id,
 				struct device_node **target, u32 *id_out)
 {
-	return of_map_id(np, id, "msi-map", "msi-map-mask",
-			 target, id_out);
+	int ret;
+
+	struct of_map_id_arg arg = {
+		.map_args = {
+			.np = *target,
+			.args_count = 1,
+			.args = { *id_out },
+		},
+	};
+
+	ret = of_map_id(np, id, "msi-map", "msi-map-mask", &arg);
+	if (!ret) {
+		*target = arg.map_args.np;
+		*id_out = arg.map_args.args[0];
+	}
+
+	return ret;
 }
 
 #define of_for_each_phandle(it, err, np, ln, cn, cc)			\
-- 
2.34.1

[PATCH v5 3/3] of: Respect #{iommu,msi}-cells in maps

[Vijayanand Jitta]

From: Robin Murphy <robin.murphy@arm.com>

So far our parsing of {iommu,msi}-map properites has always blindly
asusmed that the output specifiers will always have exactly 1 cell.
This typically does happen to be the case, but is not actually enforced
(and the PCI msi-map binding even explicitly states support for 0 or 1
cells) - as a result we've now ended up with dodgy DTs out in the field
which depend on this behaviour to map a 1-cell specifier for a 2-cell
provider, despite that being bogus per the bindings themselves.

Since there is some potential use in being able to map at least single
input IDs to multi-cell output specifiers (and properly support 0-cell
outputs as well), add support for properly parsing and using the target
nodes' #cells values, albeit with the unfortunate complication of still
having to work around expectations of the old behaviour too.

Since there are multi-cell output specifiers, the callers of of_map_id()
may need to get the exact cell output value for further processing.
Added support for that part --charan

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Vijayanand Jitta <vijayanand.jitta@oss.qualcomm.com>
---
 drivers/iommu/of_iommu.c |   4 +-
 drivers/of/base.c        | 115 +++++++++++++++++++++++++++++++--------
 include/linux/of.h       |  16 +++---
 3 files changed, 101 insertions(+), 34 deletions(-)

diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
index 646ac5a67475..768eaddf927b 100644
--- a/drivers/iommu/of_iommu.c
+++ b/drivers/iommu/of_iommu.c
@@ -46,9 +46,7 @@ static int of_iommu_configure_dev_id(struct device_node *master_np,
 				     const u32 *id)
 {
 	struct of_map_id_arg arg = {
-		.map_args = {
-			.args_count = 1,
-		},
+		.map_args = {},
 	};
 	int err;
 
diff --git a/drivers/of/base.c b/drivers/of/base.c
index 0c379fa051fe..da236108ab57 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -2092,11 +2092,38 @@ int of_find_last_cache_level(unsigned int cpu)
 	return cache_level;
 }
 
+/*
+ * Some DTs have an iommu-map targeting a 2-cell IOMMU node while
+ * specifying only 1 cell. Fortunately they all consist of value '1'
+ * as the 2nd cell entry with the same target, so check for that pattern.
+ *
+ * Example:
+ *	IOMMU node:
+ *		#iommu-cells = <2>;
+ *
+ *	Device node:
+ *		iommu-map = <0x0000 &smmu 0x0000 0x1>,
+ *			    <0x0100 &smmu 0x0100 0x1>;
+ */
+static bool of_check_bad_map(const __be32 *map, int len)
+{
+	__be32 phandle = map[1];
+
+	if (len % 4)
+		return false;
+	for (int i = 0; i < len; i += 4) {
+		if (map[i + 1] != phandle || map[i + 3] != cpu_to_be32(1))
+			return false;
+	}
+	return true;
+}
+
 /**
  * of_map_id - Translate an ID through a downstream mapping.
  * @np: root complex device node.
  * @id: device ID to map.
  * @map_name: property name of the map to use.
+ * @cells_name: property name of target specifier cells.
  * @map_mask_name: optional property name of the mask to use.
  * @arg: contains the optional params, wrapped in a struct of_phandle_args,
  *	which includes:
@@ -2114,18 +2141,19 @@ int of_find_last_cache_level(unsigned int cpu)
  *
  * Return: 0 on success or a standard error code on failure.
  */
-int of_map_id(const struct device_node *np, u32 id,
-	       const char *map_name, const char *map_mask_name,
-	       struct of_map_id_arg *arg)
+int of_map_id(const struct device_node *np, u32 id, const char *map_name,
+	      const char *cells_name, const char *map_mask_name,
+	      struct of_map_id_arg *arg)
 {
 	u32 map_mask, masked_id;
-	int map_len;
+	int map_bytes, map_len, offset = 0;
+	bool bad_map = false;
 	const __be32 *map = NULL;
 
 	if (!np || !map_name || !arg)
 		return -EINVAL;
 
-	map = of_get_property(np, map_name, &map_len);
+	map = of_get_property(np, map_name, &map_bytes);
 	if (!map) {
 		if (arg->map_args.np)
 			return -ENODEV;
@@ -2134,11 +2162,9 @@ int of_map_id(const struct device_node *np, u32 id,
 		return 0;
 	}
 
-	if (!map_len || map_len % (4 * sizeof(*map))) {
-		pr_err("%pOF: Error: Bad %s length: %d\n", np,
-			map_name, map_len);
-		return -EINVAL;
-	}
+	if (map_bytes % sizeof(*map))
+		goto err_map_len;
+	map_len = map_bytes / sizeof(*map);
 
 	/* The default is to select all bits. */
 	map_mask = 0xffffffff;
@@ -2151,27 +2177,63 @@ int of_map_id(const struct device_node *np, u32 id,
 		of_property_read_u32(np, map_mask_name, &map_mask);
 
 	masked_id = map_mask & id;
-	for ( ; map_len > 0; map_len -= 4 * sizeof(*map), map += 4) {
+	while (offset < map_len) {
 		struct device_node *phandle_node;
-		u32 id_base = be32_to_cpup(map + 0);
-		u32 phandle = be32_to_cpup(map + 1);
-		u32 out_base = be32_to_cpup(map + 2);
-		u32 id_len = be32_to_cpup(map + 3);
+		u32 id_base, phandle, id_len, id_off, cells = 0;
+		const __be32 *out_base;
+
+		if (map_len - offset < 2)
+			goto err_map_len;
+
+		id_base = be32_to_cpup(map + offset);
 
 		if (id_base & ~map_mask) {
-			pr_err("%pOF: Invalid %s translation - %s-mask (0x%x) ignores id-base (0x%x)\n",
-				np, map_name, map_name,
-				map_mask, id_base);
+			pr_err("%pOF: Invalid %s translation - %s (0x%x) ignores id-base (0x%x)\n",
+			       np, map_name, map_mask_name, map_mask, id_base);
 			return -EFAULT;
 		}
 
-		if (masked_id < id_base || masked_id >= id_base + id_len)
-			continue;
 
+		phandle = be32_to_cpup(map + offset + 1);
 		phandle_node = of_find_node_by_phandle(phandle);
 		if (!phandle_node)
 			return -ENODEV;
 
+		if (!bad_map && of_property_read_u32(phandle_node, cells_name, &cells)) {
+			pr_err("%pOF: missing %s property\n", phandle_node, cells_name);
+			return -EINVAL;
+		}
+
+		if (map_len - offset < 3 + cells)
+			goto err_map_len;
+
+		if (offset == 0 && cells == 2) {
+			bad_map = of_check_bad_map(map, map_len);
+			if (bad_map) {
+				pr_warn_once("%pOF: %s mismatches target %s, assuming extra cell of 0\n",
+					     np, map_name, cells_name);
+				cells = 1;
+			}
+		}
+
+		out_base = map + offset + 2;
+		offset += 3 + cells;
+
+		id_len = be32_to_cpup(map + offset - 1);
+		if (id_len > 1 && cells > 1) {
+			/*
+			 * With 1 output cell we reasonably assume its value
+			 * has a linear relationship to the input; with more,
+			 * we'd need help from the provider to know what to do.
+			 */
+			pr_err("%pOF: Unsupported %s - cannot handle %d-ID range with %d-cell output specifier\n",
+			       np, map_name, id_len, cells);
+			return -EINVAL;
+		}
+		id_off = masked_id - id_base;
+		if (masked_id < id_base || id_off >= id_len)
+			continue;
+
 		if (arg->map_args.np)
 			of_node_put(phandle_node);
 		else
@@ -2180,11 +2242,14 @@ int of_map_id(const struct device_node *np, u32 id,
 		if (arg->map_args.np != phandle_node)
 			continue;
 
-		arg->map_args.args[0] = masked_id - id_base + out_base;
+		for (int i = 0; i < cells; i++)
+			arg->map_args.args[i] = (id_off + be32_to_cpu(out_base[i]));
+
+		arg->map_args.args_count = cells;
 
 		pr_debug("%pOF: %s, using mask %08x, id-base: %08x, out-base: %08x, length: %08x, id: %08x -> %08x\n",
-			np, map_name, map_mask, id_base, out_base,
-			id_len, id, masked_id - id_base + out_base);
+			np, map_name, map_mask, id_base, be32_to_cpup(out_base),
+			id_len, id, id_off + be32_to_cpup(out_base));
 		return 0;
 	}
 
@@ -2194,5 +2259,9 @@ int of_map_id(const struct device_node *np, u32 id,
 	/* Bypasses translation */
 	arg->map_args.args[0] = id;
 	return 0;
+
+err_map_len:
+	pr_err("%pOF: Error: Bad %s length: %d\n", np, map_name, map_bytes);
+	return -EINVAL;
 }
 EXPORT_SYMBOL_GPL(of_map_id);
diff --git a/include/linux/of.h b/include/linux/of.h
index 514f4f018f99..acbf4fe5b16e 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -465,9 +465,9 @@ const char *of_prop_next_string(const struct property *prop, const char *cur);
 
 bool of_console_check(const struct device_node *dn, char *name, int index);
 
-int of_map_id(const struct device_node *np, u32 id,
-	       const char *map_name, const char *map_mask_name,
-	       struct of_map_id_arg *arg);
+int of_map_id(const struct device_node *np, u32 id, const char *map_name,
+	      const char *cells_name, const char *map_mask_name,
+	      struct of_map_id_arg *arg);
 
 phys_addr_t of_dma_get_max_cpu_address(struct device_node *np);
 
@@ -931,9 +931,9 @@ static inline void of_property_clear_flag(struct property *p, unsigned long flag
 {
 }
 
-static inline int of_map_id(const struct device_node *np, u32 id,
-			     const char *map_name, const char *map_mask_name,
-			     struct of_map_id_arg *arg)
+static inline int of_map_id(const struct device_node *np, u32 id, const char *map_name,
+			    const char *cells_name, const char *map_mask_name,
+			    struct of_map_id_arg *arg);
 {
 	return -EINVAL;
 }
@@ -1464,7 +1464,7 @@ static inline int of_property_read_s32(const struct device_node *np,
 static inline int of_map_iommu_id(const struct device_node *np, u32 id,
 				  struct of_map_id_arg *arg)
 {
-	return of_map_id(np, id, "iommu-map", "iommu-map-mask", arg);
+	return of_map_id(np, id, "iommu-map", "#iommu-cells", "iommu-map-mask", arg);
 }
 
 static inline int of_map_msi_id(const struct device_node *np, u32 id,
@@ -1480,7 +1480,7 @@ static inline int of_map_msi_id(const struct device_node *np, u32 id,
 		},
 	};
 
-	ret = of_map_id(np, id, "msi-map", "msi-map-mask", &arg);
+	ret = of_map_id(np, id, "msi-map", "#msi-cells", "msi-map-mask", &arg);
 	if (!ret) {
 		*target = arg.map_args.np;
 		*id_out = arg.map_args.args[0];
-- 
2.34.1

Re: [PATCH v5 3/3] of: Respect #{iommu,msi}-cells in maps

[kernel test robot]

Hi Vijayanand,

kernel test robot noticed the following build errors:

[auto build test ERROR on robh/for-next]
[also build test ERROR on pci/next pci/for-linus xen-tip/linux-next linus/master v6.19-rc5 next-20260116]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Vijayanand-Jitta/of-Add-convenience-wrappers-for-of_map_id/20260119-021706
base:   https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git for-next
patch link:    https://lore.kernel.org/r/20260118181125.1436036-4-vijayanand.jitta%40oss.qualcomm.com
patch subject: [PATCH v5 3/3] of: Respect #{iommu,msi}-cells in maps
config: i386-allnoconfig (https://download.01.org/0day-ci/archive/20260119/202601190432.C5Aya7rJ-lkp@intel.com/config)
compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260119/202601190432.C5Aya7rJ-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202601190432.C5Aya7rJ-lkp@intel.com/

All error/warnings (new ones prefixed by >>):

   In file included from include/linux/cpufreq.h:17,
                    from kernel/sched/sched.h:31,
                    from kernel/sched/rq-offsets.c:5:
>> include/linux/of.h:937:1: error: expected identifier or '(' before '{' token
     937 | {
         | ^
>> include/linux/of.h:934:19: warning: 'of_map_id' used but never defined
     934 | static inline int of_map_id(const struct device_node *np, u32 id, const char *map_name,
         |                   ^~~~~~~~~
   make[3]: *** [scripts/Makefile.build:182: kernel/sched/rq-offsets.s] Error 1
   make[3]: Target 'prepare' not remade because of errors.
   make[2]: *** [Makefile:1314: prepare0] Error 2
   make[2]: Target 'prepare' not remade because of errors.
   make[1]: *** [Makefile:248: __sub-make] Error 2
   make[1]: Target 'prepare' not remade because of errors.
   make: *** [Makefile:248: __sub-make] Error 2
   make: Target 'prepare' not remade because of errors.


vim +937 include/linux/of.h

0384e8c6c6fa49 Pantelis Antoniou 2015-01-21  933  
eb8f695e71ec36 Robin Murphy      2026-01-18 @934  static inline int of_map_id(const struct device_node *np, u32 id, const char *map_name,
eb8f695e71ec36 Robin Murphy      2026-01-18  935  			    const char *cells_name, const char *map_mask_name,
eb8f695e71ec36 Robin Murphy      2026-01-18  936  			    struct of_map_id_arg *arg);
2a6db719c92dbf Nipun Gupta       2018-09-10 @937  {
2a6db719c92dbf Nipun Gupta       2018-09-10  938  	return -EINVAL;
2a6db719c92dbf Nipun Gupta       2018-09-10  939  }
2a6db719c92dbf Nipun Gupta       2018-09-10  940  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH v5 3/3] of: Respect #{iommu,msi}-cells in maps

[kernel test robot]

Hi Vijayanand,

kernel test robot noticed the following build errors:

[auto build test ERROR on robh/for-next]
[also build test ERROR on pci/next pci/for-linus xen-tip/linux-next linus/master v6.19-rc5 next-20260116]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Vijayanand-Jitta/of-Add-convenience-wrappers-for-of_map_id/20260119-021706
base:   https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git for-next
patch link:    https://lore.kernel.org/r/20260118181125.1436036-4-vijayanand.jitta%40oss.qualcomm.com
patch subject: [PATCH v5 3/3] of: Respect #{iommu,msi}-cells in maps
config: hexagon-allnoconfig (https://download.01.org/0day-ci/archive/20260119/202601190548.wFIEEgJC-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 9b8addffa70cee5b2acc5454712d9cf78ce45710)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260119/202601190548.wFIEEgJC-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202601190548.wFIEEgJC-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from kernel/sched/rq-offsets.c:5:
   In file included from kernel/sched/sched.h:31:
   In file included from include/linux/cpufreq.h:17:
>> include/linux/of.h:937:1: error: expected identifier or '('
     937 | {
         | ^
   1 error generated.
   make[3]: *** [scripts/Makefile.build:182: kernel/sched/rq-offsets.s] Error 1
   make[3]: Target 'prepare' not remade because of errors.
   make[2]: *** [Makefile:1314: prepare0] Error 2
   make[2]: Target 'prepare' not remade because of errors.
   make[1]: *** [Makefile:248: __sub-make] Error 2
   make[1]: Target 'prepare' not remade because of errors.
   make: *** [Makefile:248: __sub-make] Error 2
   make: Target 'prepare' not remade because of errors.


vim +937 include/linux/of.h

0384e8c6c6fa49 Pantelis Antoniou 2015-01-21  933  
eb8f695e71ec36 Robin Murphy      2026-01-18  934  static inline int of_map_id(const struct device_node *np, u32 id, const char *map_name,
eb8f695e71ec36 Robin Murphy      2026-01-18  935  			    const char *cells_name, const char *map_mask_name,
eb8f695e71ec36 Robin Murphy      2026-01-18  936  			    struct of_map_id_arg *arg);
2a6db719c92dbf Nipun Gupta       2018-09-10 @937  {
2a6db719c92dbf Nipun Gupta       2018-09-10  938  	return -EINVAL;
2a6db719c92dbf Nipun Gupta       2018-09-10  939  }
2a6db719c92dbf Nipun Gupta       2018-09-10  940  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH v5 3/3] of: Respect #{iommu,msi}-cells in maps

[Vijayanand Jitta]

On 1/19/2026 2:34 AM, kernel test robot wrote:
> Hi Vijayanand,
> 
> kernel test robot noticed the following build errors:
> 
> [auto build test ERROR on robh/for-next]
> [also build test ERROR on pci/next pci/for-linus xen-tip/linux-next linus/master v6.19-rc5 next-20260116]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
> 
> url:    https://github.com/intel-lab-lkp/linux/commits/Vijayanand-Jitta/of-Add-convenience-wrappers-for-of_map_id/20260119-021706
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git for-next
> patch link:    https://lore.kernel.org/r/20260118181125.1436036-4-vijayanand.jitta%40oss.qualcomm.com
> patch subject: [PATCH v5 3/3] of: Respect #{iommu,msi}-cells in maps
> config: i386-allnoconfig (https://download.01.org/0day-ci/archive/20260119/202601190432.C5Aya7rJ-lkp@intel.com/config)
> compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260119/202601190432.C5Aya7rJ-lkp@intel.com/reproduce)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202601190432.C5Aya7rJ-lkp@intel.com/
> 
> All error/warnings (new ones prefixed by >>):
> 
>    In file included from include/linux/cpufreq.h:17,
>                     from kernel/sched/sched.h:31,
>                     from kernel/sched/rq-offsets.c:5:
>>> include/linux/of.h:937:1: error: expected identifier or '(' before '{' token
>      937 | {
>          | ^
>>> include/linux/of.h:934:19: warning: 'of_map_id' used but never defined
>      934 | static inline int of_map_id(const struct device_node *np, u32 id, const char *map_name,
>          |                   ^~~~~~~~~
>    make[3]: *** [scripts/Makefile.build:182: kernel/sched/rq-offsets.s] Error 1
>    make[3]: Target 'prepare' not remade because of errors.
>    make[2]: *** [Makefile:1314: prepare0] Error 2
>    make[2]: Target 'prepare' not remade because of errors.
>    make[1]: *** [Makefile:248: __sub-make] Error 2
>    make[1]: Target 'prepare' not remade because of errors.
>    make: *** [Makefile:248: __sub-make] Error 2
>    make: Target 'prepare' not remade because of errors.
> 
> 
> vim +937 include/linux/of.h
> 
> 0384e8c6c6fa49 Pantelis Antoniou 2015-01-21  933  
> eb8f695e71ec36 Robin Murphy      2026-01-18 @934  static inline int of_map_id(const struct device_node *np, u32 id, const char *map_name,
> eb8f695e71ec36 Robin Murphy      2026-01-18  935  			    const char *cells_name, const char *map_mask_name,
> eb8f695e71ec36 Robin Murphy      2026-01-18  936  			    struct of_map_id_arg *arg);
> 2a6db719c92dbf Nipun Gupta       2018-09-10 @937  {
> 2a6db719c92dbf Nipun Gupta       2018-09-10  938  	return -EINVAL;
> 2a6db719c92dbf Nipun Gupta       2018-09-10  939  }
> 2a6db719c92dbf Nipun Gupta       2018-09-10  940  
> 

Acknowledged. Apologies for the oversight, I will fix this and submit v6 shortly.

Thanks,
Vijay