On 01/07/16 13:40, Will Deacon wrote:
> On Tue, Jun 28, 2016 at 04:48:27PM +0100, Robin Murphy wrote:
>> With the device <-> stream ID relationship suitably abstracted and
>> of_xlate() hooked up, the PCI dependency now looks, and is, entirely
>> arbitrary. Any bus using the of_dma_configure() mechanism will work,
>> so extend support to the platform and AMBA buses which do just that.
>>
>> Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
>> ---
>>
>> v3: Now actually tested; improve comment about duplicate IDs.
>>
>> drivers/iommu/Kconfig | 2 +-
>> drivers/iommu/arm-smmu-v3.c | 42 ++++++++++++++++++++++++++++++++++--------
>> 2 files changed, 35 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
>> index ad0860383cb3..d1c66afefeed 100644
>> --- a/drivers/iommu/Kconfig
>> +++ b/drivers/iommu/Kconfig
>> @@ -308,7 +308,7 @@ config ARM_SMMU
>>
>> config ARM_SMMU_V3
>> bool "ARM Ltd. System MMU Version 3 (SMMUv3) Support"
>> - depends on ARM64 && PCI
>> + depends on ARM64
>> select IOMMU_API
>> select IOMMU_IO_PGTABLE_LPAE
>> select GENERIC_MSI_IRQ_DOMAIN
>> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
>> index 8ce2a4f9342b..735690e03818 100644
>> --- a/drivers/iommu/arm-smmu-v3.c
>> +++ b/drivers/iommu/arm-smmu-v3.c
>> @@ -35,6 +35,8 @@
>> #include <linux/pci.h>
>> #include <linux/platform_device.h>
>>
>> +#include <linux/amba/bus.h>
>> +
>> #include "io-pgtable.h"
>>
>> /* MMIO registers */
>> @@ -1822,6 +1824,25 @@ static void arm_smmu_remove_device(struct device *dev)
>> iommu_fwspec_free(dev);
>> }
>>
>> +static struct iommu_group *arm_smmu_device_group(struct device *dev)
>> +{
>> + struct iommu_group *group;
>> +
>> + /*
>> + * The difficulty of efficient stream-ID-to-device lookup prevents us
>> + * from reasonably detecting aliasing outside of PCI buses, but for the
>> + * the same underlying reason (a sparse 32-bit ID space) there's also
>
> extra 'the'
Oops, thanks.
>> + * little excuse for systems to be wired up with non-unique IDs in the
>> + * first place; consider them unsupported.
>> + */
>
> This is a long-winded way of saying "we don't support aliasing SIDs outside
> of PCI".
It is. Someone said of the original terse 2-line comment "Worse: what if
a SID in the DT aliases with a PCI master? It might be nice to have some
basic sanity checking, at least.", so I expanded it to better clarify
why there isn't. I'll try making it a little less florid.
Robin.
>
> Will
>
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