[V3,6/8] iommu: Add of_xlate callback

Commit Message

Oleksandr Tyshchenko Aug. 20, 2019, 6:09 p.m. UTC

From: Oleksandr Tyshchenko <[e-mail]>

According to the generic IOMMU DT bindings [1] the context of
required properties for IOMMU device/master node (#iommu-cells, iommus)
depends on many factors and is really driver depended thing.

We need some way to provide the driver with DT IOMMU specifier which
describes the IOMMU master interfaces of that device (device IDs, etc)
to let it decide how to interpret them. For that reason we can borrow
Linux's "of_xlate" callback.

All IOMMU drivers which support generic IOMMU DT bindings should use
this callback.

Subsequent patches will use of that support.

[1] https://www.kernel.org/doc/Documentation/devicetree/bindings/iommu/iommu.txt

Signed-off-by: Oleksandr Tyshchenko <[e-mail]>
CC: Julien Grall <[e-mail]>
CC: Jan Beulich <[e-mail]>
---
 xen/include/xen/iommu.h | 10 ++++++++++
 1 file changed, 10 insertions(+)

Comments

Jan Beulich Aug. 27, 2019, 1:30 p.m. UTC | #1

On 20.08.2019 20:09, Oleksandr Tyshchenko wrote:
> --- a/xen/include/xen/iommu.h
> +++ b/xen/include/xen/iommu.h
> @@ -240,6 +240,16 @@ struct iommu_ops {
>       int __must_check (*iotlb_flush_all)(struct domain *d);
>       int (*get_reserved_device_memory)(iommu_grdm_t *, void *);
>       void (*dump_p2m_table)(struct domain *d);
> +
> +#ifdef CONFIG_HAS_DEVICE_TREE
> +    /*
> +     * All IOMMU drivers which support generic IOMMU DT bindings should use
> +     * this callback. This is a way for the framework to provide the driver
> +     * with DT IOMMU specifier which describes the IOMMU master interfaces of
> +     * that device (device IDs, etc).
> +     */
> +    int (*of_xlate)(device_t *dev, struct dt_phandle_args *args);
> +#endif
>   };

I think this should be folded into the first patch using it. Doing
so may also answer my question of what "of" here stands for.

Jan

Oleksandr Tyshchenko Aug. 27, 2019, 2:59 p.m. UTC | #2

Hi Jan

> On 20.08.2019 20:09, Oleksandr Tyshchenko wrote:
>> --- a/xen/include/xen/iommu.h
>> +++ b/xen/include/xen/iommu.h
>> @@ -240,6 +240,16 @@ struct iommu_ops {
>>       int __must_check (*iotlb_flush_all)(struct domain *d);
>>       int (*get_reserved_device_memory)(iommu_grdm_t *, void *);
>>       void (*dump_p2m_table)(struct domain *d);
>> +
>> +#ifdef CONFIG_HAS_DEVICE_TREE
>> +    /*
>> +     * All IOMMU drivers which support generic IOMMU DT bindings 
>> should use
>> +     * this callback. This is a way for the framework to provide the 
>> driver
>> +     * with DT IOMMU specifier which describes the IOMMU master 
>> interfaces of
>> +     * that device (device IDs, etc).
>> +     */
>> +    int (*of_xlate)(device_t *dev, struct dt_phandle_args *args);
>> +#endif
>>   };
>
> I think this should be folded into the first patch using it. Doing
> so may also answer my question of what "of" here stands for.

In Linux, code related to the device-tree is prefixed with "of_". But, 
in Xen, code related to the device-tree is prefixed with "dt_" [1]. 
Looks like, I should have named it "dt_xlate" to be consistent.
There was a preference to introduce callback in a separate patch [2]. 
Anyway, shall I fold it?


[1] 
https://github.com/xen-project/xen/blob/master/xen/include/xen/device_tree.h
[2] 
https://lists.xenproject.org/archives/html/xen-devel/2019-08/msg01393.html

Jan Beulich Aug. 27, 2019, 3:11 p.m. UTC | #3

On 27.08.2019 16:59, Oleksandr wrote:
> There was a preference to introduce callback in a separate patch [2]. Anyway, shall I fold it?

Hmm, I disagree with Julien here. I don't think we should have unused
hooks in the tree, not even intermediately.

Jan

Julien Grall Sept. 9, 2019, 12:37 p.m. UTC | #4

Hi,

On 8/27/19 4:11 PM, Jan Beulich wrote:
> On 27.08.2019 16:59, Oleksandr wrote:
>> There was a preference to introduce callback in a separate patch [2]. 
>> Anyway, shall I fold it?
> 
> Hmm, I disagree with Julien here. I don't think we should have unused
> hooks in the tree, not even intermediately.

I have stated my preference before, but this is not a strong one nor a 
must. If this is your condition to get the series accepted, then 
Oleksandr should follow your requested.

Cheers,

Oleksandr Tyshchenko Sept. 9, 2019, 2:28 p.m. UTC | #5

On 09.09.19 15:37, Julien Grall wrote:
> Hi,

Hi, all.


>
>
> On 8/27/19 4:11 PM, Jan Beulich wrote:
>> On 27.08.2019 16:59, Oleksandr wrote:
>>> There was a preference to introduce callback in a separate patch 
>>> [2]. Anyway, shall I fold it?
>>
>> Hmm, I disagree with Julien here. I don't think we should have unused
>> hooks in the tree, not even intermediately.
>
> I have stated my preference before, but this is not a strong one nor a 
> must. If this is your condition to get the series accepted, then 
> Oleksandr should follow your requested.

Will fold it as requested. And will rename callback to "dt_xlate".


>
> Cheers,
>

Patch

diff --git a/xen/include/xen/iommu.h b/xen/include/xen/iommu.h
index 48f8748..79b86ac 100644
--- a/xen/include/xen/iommu.h
+++ b/xen/include/xen/iommu.h
@@ -240,6 +240,16 @@  struct iommu_ops {
     int __must_check (*iotlb_flush_all)(struct domain *d);
     int (*get_reserved_device_memory)(iommu_grdm_t *, void *);
     void (*dump_p2m_table)(struct domain *d);
+
+#ifdef CONFIG_HAS_DEVICE_TREE
+    /*
+     * All IOMMU drivers which support generic IOMMU DT bindings should use
+     * this callback. This is a way for the framework to provide the driver
+     * with DT IOMMU specifier which describes the IOMMU master interfaces of
+     * that device (device IDs, etc).
+     */
+    int (*of_xlate)(device_t *dev, struct dt_phandle_args *args);
+#endif
 };
 
 #include <asm/iommu.h>