From: Bjorn Andersson bjorn.andersson@linaro.org
commit f9081b8ff5934b8d69c748d0200e844cadd2c667 upstream.
The firmware found in some Qualcomm platforms intercepts writes to S2CR in order to replace bypass type streams with fault; and ignore S2CR updates of type fault.
Detect this behavior and implement a custom write_s2cr function in order to trick the firmware into supporting bypass streams by the means of configuring the stream for translation using a reserved and disabled context bank.
Also circumvent the problem of configuring faulting streams by configuring the stream as bypass.
Cc: stable@vger.kernel.org Signed-off-by: Bjorn Andersson bjorn.andersson@linaro.org Tested-by: Steev Klimaszewski steev@kali.org Acked-by: Robin Murphy robin.murphy@arm.com Link: https://lore.kernel.org/r/20201019182323.3162386-4-bjorn.andersson@linaro.or... Signed-off-by: Will Deacon will@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 67 +++++++++++++++++++++++++++++ 1 file changed, 67 insertions(+)
--- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c @@ -10,8 +10,15 @@
struct qcom_smmu { struct arm_smmu_device smmu; + bool bypass_quirk; + u8 bypass_cbndx; };
+static struct qcom_smmu *to_qcom_smmu(struct arm_smmu_device *smmu) +{ + return container_of(smmu, struct qcom_smmu, smmu); +} + static const struct of_device_id qcom_smmu_client_of_match[] __maybe_unused = { { .compatible = "qcom,adreno" }, { .compatible = "qcom,mdp4" }, @@ -25,9 +32,33 @@ static const struct of_device_id qcom_sm
static int qcom_smmu_cfg_probe(struct arm_smmu_device *smmu) { + unsigned int last_s2cr = ARM_SMMU_GR0_S2CR(smmu->num_mapping_groups - 1); + struct qcom_smmu *qsmmu = to_qcom_smmu(smmu); + u32 reg; u32 smr; int i;
+ /* + * With some firmware versions writes to S2CR of type FAULT are + * ignored, and writing BYPASS will end up written as FAULT in the + * register. Perform a write to S2CR to detect if this is the case and + * if so reserve a context bank to emulate bypass streams. + */ + reg = FIELD_PREP(ARM_SMMU_S2CR_TYPE, S2CR_TYPE_BYPASS) | + FIELD_PREP(ARM_SMMU_S2CR_CBNDX, 0xff) | + FIELD_PREP(ARM_SMMU_S2CR_PRIVCFG, S2CR_PRIVCFG_DEFAULT); + arm_smmu_gr0_write(smmu, last_s2cr, reg); + reg = arm_smmu_gr0_read(smmu, last_s2cr); + if (FIELD_GET(ARM_SMMU_S2CR_TYPE, reg) != S2CR_TYPE_BYPASS) { + qsmmu->bypass_quirk = true; + qsmmu->bypass_cbndx = smmu->num_context_banks - 1; + + set_bit(qsmmu->bypass_cbndx, smmu->context_map); + + reg = FIELD_PREP(ARM_SMMU_CBAR_TYPE, CBAR_TYPE_S1_TRANS_S2_BYPASS); + arm_smmu_gr1_write(smmu, ARM_SMMU_GR1_CBAR(qsmmu->bypass_cbndx), reg); + } + for (i = 0; i < smmu->num_mapping_groups; i++) { smr = arm_smmu_gr0_read(smmu, ARM_SMMU_GR0_SMR(i));
@@ -45,6 +76,41 @@ static int qcom_smmu_cfg_probe(struct ar return 0; }
+static void qcom_smmu_write_s2cr(struct arm_smmu_device *smmu, int idx) +{ + struct arm_smmu_s2cr *s2cr = smmu->s2crs + idx; + struct qcom_smmu *qsmmu = to_qcom_smmu(smmu); + u32 cbndx = s2cr->cbndx; + u32 type = s2cr->type; + u32 reg; + + if (qsmmu->bypass_quirk) { + if (type == S2CR_TYPE_BYPASS) { + /* + * Firmware with quirky S2CR handling will substitute + * BYPASS writes with FAULT, so point the stream to the + * reserved context bank and ask for translation on the + * stream + */ + type = S2CR_TYPE_TRANS; + cbndx = qsmmu->bypass_cbndx; + } else if (type == S2CR_TYPE_FAULT) { + /* + * Firmware with quirky S2CR handling will ignore FAULT + * writes, so trick it to write FAULT by asking for a + * BYPASS. + */ + type = S2CR_TYPE_BYPASS; + cbndx = 0xff; + } + } + + reg = FIELD_PREP(ARM_SMMU_S2CR_TYPE, type) | + FIELD_PREP(ARM_SMMU_S2CR_CBNDX, cbndx) | + FIELD_PREP(ARM_SMMU_S2CR_PRIVCFG, s2cr->privcfg); + arm_smmu_gr0_write(smmu, ARM_SMMU_GR0_S2CR(idx), reg); +} + static int qcom_smmu_def_domain_type(struct device *dev) { const struct of_device_id *match = @@ -86,6 +152,7 @@ static const struct arm_smmu_impl qcom_s .cfg_probe = qcom_smmu_cfg_probe, .def_domain_type = qcom_smmu_def_domain_type, .reset = qcom_smmu500_reset, + .write_s2cr = qcom_smmu_write_s2cr, };
struct arm_smmu_device *qcom_smmu_impl_init(struct arm_smmu_device *smmu)