On Mon, Jul 25, 2016 at 04:09:55PM +0100, Robin Murphy wrote:

Hi Lorenzo,

On 20/07/16 12:23, Lorenzo Pieralisi wrote:

quoted

The iommu_fwspec structure, used to hold per device iommu configuration
data is not OF specific and therefore can be moved to a generic
and OF independent compilation unit.

In particular, the iommu_fwspec handling hinges on the device_node
pointer to identify the IOMMU device associated with the iommu_fwspec
structure, that is easily converted to a more generic fwnode_handle
pointer that can cater for OF and non-OF (ie ACPI) systems.

Create the files and related Kconfig entry to decouple iommu_fwspec
structure from the OF iommu kernel layer.

Given that the current iommu_fwspec implementation relies on
the arch specific struct device.archdata.iommu field in its
implementation, by making the code standalone and independent
of the OF layer this patch makes sure that the iommu_fwspec
kernel code can be selected only on arches implementing the
struct device.archdata.iommu field by adding an explicit
arch dependency in its config entry.

Current drivers using the iommu_fwspec for streamid translation
are converted to the new iommu_fwspec API by simply converting
the device_node to its fwnode_handle pointer.

Signed-off-by: Lorenzo Pieralisi <redacted>
Cc: Will Deacon <redacted>
Cc: Hanjun Guo <redacted>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Joerg Roedel <joro@8bytes.org>
---
 drivers/iommu/Kconfig        |   4 ++
 drivers/iommu/Makefile       |   1 +
 drivers/iommu/arm-smmu-v3.c  |  13 +++--
 drivers/iommu/iommu-fwspec.c | 114 +++++++++++++++++++++++++++++++++++++++++++
 drivers/iommu/of_iommu.c     |  52 --------------------
 include/linux/iommu-fwspec.h |  60 +++++++++++++++++++++++
 include/linux/of_iommu.h     |  24 +++------
 7 files changed, 196 insertions(+), 72 deletions(-)
 create mode 100644 drivers/iommu/iommu-fwspec.c
 create mode 100644 include/linux/iommu-fwspec.h

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index d1c66af..2b26bfb 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig

@@ -67,6 +67,10 @@ config OF_IOMMU
        def_bool y
        depends on OF && IOMMU_API
 
+config IOMMU_FWSPEC
+       def_bool y
+       depends on ARM64 && IOMMU_API

I think that could be at least (ARM || ARM64).

Yes agreed.

quoted

 # IOMMU-agnostic DMA-mapping layer
 config IOMMU_DMA
 	bool

[...]

quoted

diff --git a/include/linux/of_iommu.h b/include/linux/of_iommu.h
index 308791f..2362232 100644
--- a/include/linux/of_iommu.h
+++ b/include/linux/of_iommu.h

@@ -15,13 +15,8 @@ extern void of_iommu_init(void);
 extern const struct iommu_ops *of_iommu_configure(struct device *dev,
 					struct device_node *master_np);
 
-struct iommu_fwspec {
-	const struct iommu_ops	*iommu_ops;
-	struct device_node	*iommu_np;
-	void			*iommu_priv;
-	unsigned int		num_ids;
-	u32			ids[];
-};
+void of_iommu_set_ops(struct device_node *np, const struct iommu_ops *ops);
+const struct iommu_ops *of_iommu_get_ops(struct device_node *np);

Is there some reason we need to retain the existing definitions of
these? I was assuming we'd be able to move the entire implementation
over to the fwspec code and leave behind nothing more than trivial
wrappers, e.g.:

#define of_iommu_get_ops(np) iommu_fwspec_get_ops(&(np)->fwnode_handle)

Yep, that's exactly what I did but then I was bitten by config
dependencies. If we implement of_iommu_get/set_ops() as wrappers,
we have to compile iommu_fwspec_get/set_ops() on arches that may
not have struct dev_archdata.iommu, unless we introduce yet another
config symbol to avoid compiling that code (see eg iommu_fwspec_init(),
we can't compile it on eg x86 even though we do need of_iommu_get_ops()
on it - so iommu_fwspec_get_ops(), that lives in the same compilation
unit as eg iommu_fwspec_init()).

So short answer is: there is no reason apart from dev_archdata.iommu
being arch specific, if we were able to move iommu_fwspec to generic
code (ie struct device, somehow) I would certainly get rid of this
stupid code duplication (or as I said I can add a config entry for
that, more ideas are welcome).

Thanks,
Lorenzo

Robin.

quoted

 #else
 

@@ -39,17 +34,14 @@ static inline const struct iommu_ops *of_iommu_configure(struct device *dev,
 	return NULL;
 }
 
-struct iommu_fwspec;
-
-#endif	/* CONFIG_OF_IOMMU */
+static inline void of_iommu_set_ops(struct device_node *np,
+				    const struct iommu_ops *ops)
+{ }
 
-int iommu_fwspec_init(struct device *dev, struct device_node *iommu_np);
-void iommu_fwspec_free(struct device *dev);
-int iommu_fwspec_add_ids(struct device *dev, u32 *ids, int num_ids);
-struct iommu_fwspec *dev_iommu_fwspec(struct device *dev);
+static inline const struct iommu_ops *
+of_iommu_get_ops(struct device_node *np) { return NULL; }
 
-void of_iommu_set_ops(struct device_node *np, const struct iommu_ops *ops);
-const struct iommu_ops *of_iommu_get_ops(struct device_node *np);
+#endif	/* CONFIG_OF_IOMMU */
 
 extern struct of_device_id __iommu_of_table;