The generic IOMMU device-tree bindings can be used to add arbitrary OF
masters to an IOMMU with a compliant binding.
This patch introduces of_iommu_configure, which does exactly that. A
list of iommu_dma_mapping structures are created for each device, which
represent the set of IOMMU instances through which the device can
master. The list is protected by a kref count and freed when no users
remain. It is expected that DMA-mapping code will take a reference if it
wishes to make use of the IOMMU information.
Signed-off-by: Will Deacon <will.dea...@arm.com>
---
drivers/iommu/Kconfig | 2 +-
drivers/iommu/of_iommu.c | 70 +++++++++++++++++++++++++++++++++++++++++++++
include/linux/dma-mapping.h | 8 ++++++
include/linux/of_iommu.h | 10 +++++++
4 files changed, 89 insertions(+), 1 deletion(-)
diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index dd5112265cc9..6d13f962f156 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -15,7 +15,7 @@ if IOMMU_SUPPORT
config OF_IOMMU
def_bool y
- depends on OF
+ depends on OF && IOMMU_API
config FSL_PAMU
bool "Freescale IOMMU support"
diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
index 13d800c4ce25..8656b63f27ee 100644
--- a/drivers/iommu/of_iommu.c
+++ b/drivers/iommu/of_iommu.c
@@ -18,9 +18,11 @@
*/
#include <linux/export.h>
+#include <linux/iommu.h>
#include <linux/limits.h>
#include <linux/of.h>
#include <linux/of_iommu.h>
+#include <linux/slab.h>
/**
* of_get_dma_window - Parse *dma-window property and returns 0 if found.
@@ -90,6 +92,74 @@ int of_get_dma_window(struct device_node *dn, const char
*prefix, int index,
}
EXPORT_SYMBOL_GPL(of_get_dma_window);
+struct iommu_dma_mapping *of_iommu_configure(struct device *dev)
+{
+ struct of_phandle_args iommu_spec;
+ struct iommu_dma_mapping *mapping;
+ struct device_node *np;
+ struct iommu_data *iommu = NULL;
+ int idx = 0;
+
+ /*
+ * We don't currently walk up the tree looking for a parent IOMMU.
+ * See the `Notes:' section of
+ * Documentation/devicetree/bindings/iommu/iommu.txt
+ */
+ while (!of_parse_phandle_with_args(dev->of_node, "iommus",
+ "#iommu-cells", idx,
+ &iommu_spec)) {
+ struct iommu_data *data;
+
+ np = iommu_spec.np;
+ data = of_iommu_get_data(np);
+
+ if (!data || !data->ops || !data->ops->of_xlate)
+ goto err_put_node;
+
+ if (!iommu) {
+ iommu = data;
+ } else if (iommu != data) {
+ /* We don't currently support multi-IOMMU masters */
+ pr_warn("Rejecting device %s with multiple IOMMU
instances\n",
+ dev_name(dev));
+ goto err_put_node;
+ }
+
+ if (!data->ops->of_xlate(dev, &iommu_spec))
+ goto err_put_node;
+
+ of_node_put(np);
+ idx++;
+ }
+
+ if (!iommu)
+ return NULL;
+
+ mapping = kzalloc(sizeof(*mapping), GFP_KERNEL);
+ if (!mapping)
+ return NULL;
+
+ kref_init(&mapping->kref);
+ INIT_LIST_HEAD(&mapping->node);
+ mapping->iommu = iommu;
+ return mapping;
+
+err_put_node:
+ of_node_put(np);
+ return NULL;
+}
+
+void of_iommu_deconfigure(struct kref *kref)
+{
+ struct iommu_dma_mapping *mapping, *curr, *next;
+
+ mapping = container_of(kref, struct iommu_dma_mapping, kref);
+ list_for_each_entry_safe(curr, next, &mapping->node, node) {
+ list_del(&curr->node);
+ kfree(curr);
+ }
+}
+
void __init of_iommu_init(void)
{
struct device_node *np;
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 1e944e77d38d..e60e52d82db9 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -62,6 +62,14 @@ struct dma_map_ops {
int is_phys;
};
+struct iommu_data;
+
+struct iommu_dma_mapping {
+ struct iommu_data *iommu;
+ struct list_head node;
+ struct kref kref;
+};
+
#define DMA_BIT_MASK(n) (((n) == 64) ? ~0ULL : ((1ULL<<(n))-1))
#define DMA_MASK_NONE 0x0ULL
diff --git a/include/linux/of_iommu.h b/include/linux/of_iommu.h
index 0a685e0ab33e..af6179557005 100644
--- a/include/linux/of_iommu.h
+++ b/include/linux/of_iommu.h
@@ -1,9 +1,12 @@
#ifndef __OF_IOMMU_H
#define __OF_IOMMU_H
+#include <linux/device.h>
#include <linux/iommu.h>
#include <linux/of.h>
+struct iommu_dma_mapping;
+
#ifdef CONFIG_OF_IOMMU
extern int of_get_dma_window(struct device_node *dn, const char *prefix,
@@ -11,6 +14,8 @@ extern int of_get_dma_window(struct device_node *dn, const
char *prefix,
size_t *size);
extern void of_iommu_init(void);
+extern struct iommu_dma_mapping *of_iommu_configure(struct device *dev);
+extern void of_iommu_deconfigure(struct kref *kref);
#else
@@ -22,6 +27,11 @@ static inline int of_get_dma_window(struct device_node *dn,
const char *prefix,
}
static inline void of_iommu_init(void) { }
+static inline struct iommu_dma_mapping *of_iommu_configure(struct device *dev)
+{
+ return NULL;
+}
+static inline void of_iommu_deconfigure(struct kref *kref) { }
#endif /* CONFIG_OF_IOMMU */
--
2.1.0
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