Messages in this thread | | | Subject | Re: [PATCH v3 8/8] iommu/arm-smmu-qcom: Setup identity domain for boot mappings | From | Robin Murphy <> | Date | Fri, 11 Sep 2020 18:29:23 +0100 |
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On 2020-09-04 16:55, Bjorn Andersson wrote: > With many Qualcomm platforms not having functional S2CR BYPASS a > temporary IOMMU domain, without translation, needs to be allocated in > order to allow these memory transactions. > > Unfortunately the boot loader uses the first few context banks, so > rather than overwriting a active bank the last context bank is used and > streams are diverted here during initialization. > > This also performs the readback of SMR registers for the Qualcomm > platform, to trigger the mechanism. > > This is based on prior work by Thierry Reding and Laurentiu Tudor. > > Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> > --- > > Changes since v2: > - Combined from pieces spread between the Qualcomm impl and generic code in v2. > - Moved to use the newly introduced inherit_mapping op. > > drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 33 ++++++++++++++++++++++ > 1 file changed, 33 insertions(+) > > diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c > index 70a1eaa52e14..a54302190932 100644 > --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c > +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c > @@ -12,6 +12,7 @@ > struct qcom_smmu { > struct arm_smmu_device smmu; > bool bypass_broken; > + struct iommu_domain *identity; > }; > > static struct qcom_smmu *to_qcom_smmu(struct arm_smmu_device *smmu) > @@ -228,6 +229,37 @@ static int qcom_smmu_cfg_probe(struct arm_smmu_device *smmu) > return 0; > } > > +static int qcom_smmu_inherit_mappings(struct arm_smmu_device *smmu) > +{ > + struct qcom_smmu *qsmmu = to_qcom_smmu(smmu); > + int cbndx; > + u32 smr; > + int i; > + > + qsmmu->identity = arm_smmu_alloc_identity_domain(smmu); > + if (IS_ERR(qsmmu->identity)) > + return PTR_ERR(qsmmu->identity); > + > + cbndx = to_smmu_domain(qsmmu->identity)->cfg.cbndx;
I don't really get the point of going through the dance of allocating a whole iommu_domain() just to get a context. If you don't want to simply statically reserve a context at probe time, then just allocate from smmu->context_map here (where AFAICS "here" should be in cfg_probe anyway). This is entirely driver-internal, so there shouldn't be any need for IOMMU-API-level stuff to be involved.
Robin.
> + > + for (i = 0; i < smmu->num_mapping_groups; i++) { > + smr = arm_smmu_gr0_read(smmu, ARM_SMMU_GR0_SMR(i)); > + > + if (FIELD_GET(ARM_SMMU_SMR_VALID, smr)) { > + smmu->smrs[i].id = FIELD_GET(ARM_SMMU_SMR_ID, smr); > + smmu->smrs[i].mask = FIELD_GET(ARM_SMMU_SMR_MASK, smr); > + smmu->smrs[i].valid = true; > + > + smmu->s2crs[i].type = S2CR_TYPE_TRANS; > + smmu->s2crs[i].privcfg = S2CR_PRIVCFG_DEFAULT; > + smmu->s2crs[i].cbndx = cbndx; > + smmu->s2crs[i].count++; > + } > + } > + > + return 0; > +} > + > static int qcom_smmu_def_domain_type(struct device *dev) > { > const struct of_device_id *match = > @@ -270,6 +302,7 @@ static const struct arm_smmu_impl qcom_smmu_impl = { > .cfg_probe = qcom_smmu_cfg_probe, > .def_domain_type = qcom_smmu_def_domain_type, > .reset = qcom_smmu500_reset, > + .inherit_mappings = qcom_smmu_inherit_mappings, > }; > > static const struct arm_smmu_impl qcom_adreno_smmu_impl = { >
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