[RFC PATCH 06/11] drivers: iommu: make of_xlate() interface DT agnostic

[Lorenzo Pieralisi]

On systems booting with ACPI, the IOMMU drivers require the same
kind of id mapping carried out with a DT tree through the of_xlate()
API in order to map devices identifiers to IOMMU ones.

On ACPI systems, since DT nodes are not present (ie struct
device.of_node == NULL), to identify the device requiring the translation
the struct device_node (and the structure used to pass translation
information - struct of_phandle_args - that contains a struct device_node)
cannot be used, so a generic translation structure to be used for IOMMU
mapping should be defined, based on the firmware agnostic fwnode_handle
type.

This patch mechanically refactors/renames the of_xlate API to make
it DT agnostic, by declaring a new type (struct iommu_fwspec), that
allows the kernel to pass a device identifier (fwnode - which can
represent either a DT node or an IOMMU FW node) and by changing the
of_xlate signature so that it does not take anymore the DT specific
of_phandle_args argument and replaces it with the DT agnostic
iommu_fwspec one.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
Cc: Matthias Brugger <matthias.bgg@xxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
Cc: Rob Herring <robh+dt@xxxxxxxxxx>
Cc: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx>
Cc: Robin Murphy <robin.murphy@xxxxxxx>
Cc: Tomasz Nowicki <tn@xxxxxxxxxxxx>
Cc: Joerg Roedel <joro@xxxxxxxxxx>
Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
---
 drivers/iommu/arm-smmu.c     | 12 +++++++-----
 drivers/iommu/exynos-iommu.c | 11 +++++++----
 drivers/iommu/mtk_iommu.c    | 13 ++++++++-----
 drivers/iommu/of_iommu.c     | 20 ++++++++++++++++++--
 include/linux/iommu.h        | 24 ++++++++++++++++++++----
 5 files changed, 60 insertions(+), 20 deletions(-)

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 6c42770..84bcff7 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -1440,18 +1440,20 @@ out_unlock:
 	return ret;
 }
 
-static int arm_smmu_of_xlate(struct device *dev, struct of_phandle_args *args)
+static int arm_smmu_fw_xlate(struct device *dev, struct iommu_fwspec *args)
 {
 	struct arm_smmu_device *smmu;
-	struct platform_device *smmu_pdev;
+	struct platform_device *smmu_pdev = NULL;
+
+	if (is_of_node(args->fwnode))
+		smmu_pdev = of_find_device_by_node(to_of_node(args->fwnode));
 
-	smmu_pdev = of_find_device_by_node(args->np);
 	if (!smmu_pdev)
 		return -ENODEV;
 
 	smmu = platform_get_drvdata(smmu_pdev);
 
-	return arm_smmu_add_dev_streamid(smmu, dev, args->args[0]);
+	return arm_smmu_add_dev_streamid(smmu, dev, args->param[0]);
 }
 
 static struct iommu_ops arm_smmu_ops = {
@@ -1468,7 +1470,7 @@ static struct iommu_ops arm_smmu_ops = {
 	.device_group		= arm_smmu_device_group,
 	.domain_get_attr	= arm_smmu_domain_get_attr,
 	.domain_set_attr	= arm_smmu_domain_set_attr,
-	.of_xlate		= arm_smmu_of_xlate,
+	.fw_xlate		= arm_smmu_fw_xlate,
 	.pgsize_bitmap		= -1UL, /* Restricted during device attach */
 };
 
diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
index 5ecc86c..84ff5bb 100644
--- a/drivers/iommu/exynos-iommu.c
+++ b/drivers/iommu/exynos-iommu.c
@@ -1250,13 +1250,16 @@ static void exynos_iommu_remove_device(struct device *dev)
 	iommu_group_remove_device(dev);
 }
 
-static int exynos_iommu_of_xlate(struct device *dev,
-				 struct of_phandle_args *spec)
+static int exynos_iommu_fw_xlate(struct device *dev,
+				 struct iommu_fwspec *args)
 {
 	struct exynos_iommu_owner *owner = dev->archdata.iommu;
-	struct platform_device *sysmmu = of_find_device_by_node(spec->np);
+	struct platform_device *sysmmu = NULL;
 	struct sysmmu_drvdata *data;
 
+	if (is_of_node(args->fwnode))
+		sysmmu = of_find_device_by_node(to_of_node(args->fwnode));
+
 	if (!sysmmu)
 		return -ENODEV;
 
@@ -1290,7 +1293,7 @@ static struct iommu_ops exynos_iommu_ops = {
 	.add_device = exynos_iommu_add_device,
 	.remove_device = exynos_iommu_remove_device,
 	.pgsize_bitmap = SECT_SIZE | LPAGE_SIZE | SPAGE_SIZE,
-	.of_xlate = exynos_iommu_of_xlate,
+	.fw_xlate = exynos_iommu_fw_xlate,
 };
 
 static bool init_done;
diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index 929a66a..e08dc0a 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -436,20 +436,23 @@ static struct iommu_group *mtk_iommu_device_group(struct device *dev)
 	return data->m4u_group;
 }
 
-static int mtk_iommu_of_xlate(struct device *dev, struct of_phandle_args *args)
+static int mtk_iommu_fw_xlate(struct device *dev, struct iommu_fwspec *args)
 {
 	struct mtk_iommu_client_priv *head, *priv, *next;
 	struct platform_device *m4updev;
 
-	if (args->args_count != 1) {
+	if (!is_of_node(args->fwnode))
+		return -ENODEV;
+
+	if (args->param_count != 1) {
 		dev_err(dev, "invalid #iommu-cells(%d) property for IOMMU\n",
-			args->args_count);
+			args->param_count);
 		return -EINVAL;
 	}
 
 	if (!dev->archdata.iommu) {
 		/* Get the m4u device */
-		m4updev = of_find_device_by_node(args->np);
+		m4updev = of_find_device_by_node(to_of_node(args->fwnode));
 		of_node_put(args->np);
 		if (WARN_ON(!m4updev))
 			return -EINVAL;
@@ -469,7 +472,7 @@ static int mtk_iommu_of_xlate(struct device *dev, struct of_phandle_args *args)
 	if (!priv)
 		goto err_free_mem;
 
-	priv->mtk_m4u_id = args->args[0];
+	priv->mtk_m4u_id = args->param[0];
 	list_add_tail(&priv->client, &head->client);
 
 	return 0;
diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
index 910826c..331dd78 100644
--- a/drivers/iommu/of_iommu.c
+++ b/drivers/iommu/of_iommu.c
@@ -135,6 +135,18 @@ struct iommu_ops *of_iommu_get_ops(struct device_node *np)
 	return ops;
 }
 
+static void of_phandle_args_to_fwspec(struct of_phandle_args *iommu_data,
+				      struct iommu_fwspec *fwspec)
+{
+	int i;
+
+	fwspec->fwnode = iommu_data->np ? &iommu_data->np->fwnode : NULL;
+	fwspec->param_count = iommu_data->args_count;
+
+	for (i = 0; i < iommu_data->args_count; i++)
+		fwspec->param[i] = iommu_data->args[i];
+}
+
 static int __get_pci_rid(struct pci_dev *pdev, u16 alias, void *data)
 {
 	struct of_phandle_args *iommu_spec = data;
@@ -148,6 +160,7 @@ struct iommu_ops *of_iommu_configure(struct device *dev,
 				     struct device_node *master_np)
 {
 	struct of_phandle_args iommu_spec;
+	struct iommu_fwspec fwspec;
 	struct device_node *np = NULL;
 	struct iommu_ops *ops = NULL;
 	int idx = 0;
@@ -170,8 +183,9 @@ struct iommu_ops *of_iommu_configure(struct device *dev,
 
 		iommu_spec.np = np;
 		iommu_spec.args_count = 1;
+		of_phandle_args_to_fwspec(&iommu_spec, &fwspec);
 		ops = of_iommu_get_ops(np);
-		if (!ops || !ops->of_xlate || ops->of_xlate(dev, &iommu_spec))
+		if (!ops || !ops->fw_xlate || ops->fw_xlate(dev, &fwspec))
 			goto err_put_node;
 
 		of_node_put(np);
@@ -189,7 +203,9 @@ struct iommu_ops *of_iommu_configure(struct device *dev,
 		np = iommu_spec.np;
 		ops = of_iommu_get_ops(np);
 
-		if (!ops || !ops->of_xlate || ops->of_xlate(dev, &iommu_spec))
+		of_phandle_args_to_fwspec(&iommu_spec, &fwspec);
+
+		if (!ops || !ops->fw_xlate || ops->fw_xlate(dev, &fwspec))
 			goto err_put_node;
 
 		of_node_put(np);
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 0bba25e..5184d81 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -85,6 +85,24 @@ struct iommu_domain {
 	void *iova_cookie;
 };
 
+#define IOMMU_MAP_SPEC_PARAMS 16
+
+/**
+ * struct iommu_fwspec - generic IOMMU specifier structure
+ *
+ * @fwnode:		Pointer to a firmware-specific descriptor
+ * @param_count:	Number of device-specific parameters
+ * @param:		Device-specific parameters
+ *
+ * This structure, directly modeled after of_phandle_args, is used to
+ * pass a device-specific description of an IOMMU mapping.
+ */
+struct iommu_fwspec {
+	struct fwnode_handle *fwnode;
+	int param_count;
+	u32 param[IOMMU_MAP_SPEC_PARAMS];
+};
+
 enum iommu_cap {
 	IOMMU_CAP_CACHE_COHERENCY,	/* IOMMU can enforce cache coherent DMA
 					   transactions */
@@ -155,7 +173,7 @@ struct iommu_dm_region {
  * @domain_window_disable: Disable a particular window for a domain
  * @domain_set_windows: Set the number of windows for a domain
  * @domain_get_windows: Return the number of windows for a domain
- * @of_xlate: add OF master IDs to iommu grouping
+ * @fw_xlate: add FW master IDs to iommu grouping
  * @pgsize_bitmap: bitmap of supported page sizes
  * @priv: per-instance data private to the iommu driver
  */
@@ -196,9 +214,7 @@ struct iommu_ops {
 	/* Get the number of windows per domain */
 	u32 (*domain_get_windows)(struct iommu_domain *domain);
 
-#ifdef CONFIG_OF_IOMMU
-	int (*of_xlate)(struct device *dev, struct of_phandle_args *args);
-#endif
+	int (*fw_xlate)(struct device *dev, struct iommu_fwspec *args);
 
 	unsigned long pgsize_bitmap;
 	void *priv;
-- 
2.6.4