Messages in this thread Patch in this message | | | Subject | Re: [PATCH 4/7 v5] iommu: arm-smmu: Add support for the fsl-mc bus | From | Robin Murphy <> | Date | Tue, 3 Jul 2018 17:01:49 +0100 |
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On 20/05/18 14:49, Nipun Gupta wrote: > Implement bus specific support for the fsl-mc bus including > registering arm_smmu_ops and bus specific device add operations. > > Signed-off-by: Nipun Gupta <nipun.gupta@nxp.com> > --- > drivers/iommu/arm-smmu.c | 7 +++++++ > drivers/iommu/iommu.c | 21 +++++++++++++++++++++ > include/linux/fsl/mc.h | 8 ++++++++ > include/linux/iommu.h | 2 ++ > 4 files changed, 38 insertions(+) > > diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c > index 69e7c60..e1d5090 100644 > --- a/drivers/iommu/arm-smmu.c > +++ b/drivers/iommu/arm-smmu.c > @@ -52,6 +52,7 @@ > #include <linux/spinlock.h> > > #include <linux/amba/bus.h> > +#include <linux/fsl/mc.h> > > #include "io-pgtable.h" > #include "arm-smmu-regs.h" > @@ -1459,6 +1460,8 @@ static struct iommu_group *arm_smmu_device_group(struct device *dev) > > if (dev_is_pci(dev)) > group = pci_device_group(dev); > + else if (dev_is_fsl_mc(dev)) > + group = fsl_mc_device_group(dev); > else > group = generic_device_group(dev); > > @@ -2037,6 +2040,10 @@ static void arm_smmu_bus_init(void) > bus_set_iommu(&pci_bus_type, &arm_smmu_ops); > } > #endif > +#ifdef CONFIG_FSL_MC_BUS > + if (!iommu_present(&fsl_mc_bus_type)) > + bus_set_iommu(&fsl_mc_bus_type, &arm_smmu_ops); > +#endif > } > > static int arm_smmu_device_probe(struct platform_device *pdev) > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index d2aa2320..6d4ce35 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -32,6 +32,7 @@ > #include <linux/pci.h> > #include <linux/bitops.h> > #include <linux/property.h> > +#include <linux/fsl/mc.h> > #include <trace/events/iommu.h> > > static struct kset *iommu_group_kset; > @@ -987,6 +988,26 @@ struct iommu_group *pci_device_group(struct device *dev) > return iommu_group_alloc(); > } > > +/* Get the IOMMU group for device on fsl-mc bus */ > +struct iommu_group *fsl_mc_device_group(struct device *dev) > +{ > + struct device *cont_dev = fsl_mc_cont_dev(dev); > + struct iommu_group *group; > + > + /* Container device is responsible for creating the iommu group */ > + if (fsl_mc_is_cont_dev(dev)) {
Why duplicate what fsl_mc_cont_dev() has already figured out?
AFAICS the overall operation here boils down to something like:
cont_dev = fsl_mc_cont_dev(dev); group = iommu_group_get(cont_dev); if (!group) group = iommu_group_alloc(); return group;
> + group = iommu_group_alloc(); > + if (IS_ERR(group)) > + return NULL;
iommu_group_get_for_dev() expects a PTR_ERR, so I don't think munging the return here is the right thing to do.
> + } else { > + get_device(cont_dev);
If races are a concern, isn't this a bit late? Maybe in that case you want {get,put}_fsl_mc_cont_dev() routines instead of the simple macro below. But on the other hand if dev already has cont_dev as its parent, wouldn't the reference taken in device_add() be sufficient to prevent it from vanishing unexpectedly in this timescale?
Robin.
> + group = iommu_group_get(cont_dev); > + put_device(cont_dev); > + } > + > + return group; > +} > + > /** > * iommu_group_get_for_dev - Find or create the IOMMU group for a device > * @dev: target device > diff --git a/include/linux/fsl/mc.h b/include/linux/fsl/mc.h > index f27cb14..dddaca1 100644 > --- a/include/linux/fsl/mc.h > +++ b/include/linux/fsl/mc.h > @@ -351,6 +351,14 @@ struct fsl_mc_io { > #define dev_is_fsl_mc(_dev) (0) > #endif > > +/* Macro to check if a device is a container device */ > +#define fsl_mc_is_cont_dev(_dev) (to_fsl_mc_device(_dev)->flags & \ > + FSL_MC_IS_DPRC) > + > +/* Macro to get the container device of a MC device */ > +#define fsl_mc_cont_dev(_dev) (fsl_mc_is_cont_dev(_dev) ? \ > + (_dev) : (_dev)->parent) > + > /* > * module_fsl_mc_driver() - Helper macro for drivers that don't do > * anything special in module init/exit. This eliminates a lot of > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index 19938ee..2981200 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -389,6 +389,8 @@ static inline size_t iommu_map_sg(struct iommu_domain *domain, > extern struct iommu_group *pci_device_group(struct device *dev); > /* Generic device grouping function */ > extern struct iommu_group *generic_device_group(struct device *dev); > +/* FSL-MC device grouping function */ > +struct iommu_group *fsl_mc_device_group(struct device *dev); > > /** > * struct iommu_fwspec - per-device IOMMU instance data >
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