From: Bjorn Andersson <bjorn.andersson@linaro.org>
To: Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
Joerg Roedel <joro@8bytes.org>,
Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>,
Jordan Crouse <jcrouse@codeaurora.org>,
Thierry Reding <treding@nvidia.com>,
Rob Clark <robdclark@chromium.org>
Cc: linux-arm-kernel@lists.infradead.org,
iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
linux-arm-msm@vger.kernel.org
Subject: [PATCH v5 3/3] iommu/arm-smmu-qcom: Implement S2CR quirk
Date: Mon, 19 Oct 2020 11:23:23 -0700 [thread overview]
Message-ID: <20201019182323.3162386-4-bjorn.andersson@linaro.org> (raw)
In-Reply-To: <20201019182323.3162386-1-bjorn.andersson@linaro.org>
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.
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
---
Changes since v4:
- Made the bypass_cbndx an integer...
- Separated out the "quirk enabled or not" into a bool, rather than reusing
(the valid) context bank 0 to represent this.
- Dropped the unused EXIDS handling.
drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 67 ++++++++++++++++++++++
1 file changed, 67 insertions(+)
diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c
index 48627fcf6bed..66ba4870659f 100644
--- 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_smmu_client_of_match[] __maybe_unused = {
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 arm_smmu_device *smmu)
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_smmu_impl = {
.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)
--
2.28.0
next prev parent reply other threads:[~2020-10-19 18:22 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-19 18:23 [PATCH v5 0/3] iommu/arm-smmu-qcom: Support maintaining bootloader mappings Bjorn Andersson
2020-10-19 18:23 ` [PATCH v5 1/3] iommu/arm-smmu: Allow implementation specific write_s2cr Bjorn Andersson
2020-10-19 18:23 ` [PATCH v5 2/3] iommu/arm-smmu-qcom: Read back stream mappings Bjorn Andersson
2020-10-19 18:50 ` Robin Murphy
2020-10-19 18:23 ` Bjorn Andersson [this message]
2020-10-19 19:02 ` [PATCH v5 3/3] iommu/arm-smmu-qcom: Implement S2CR quirk Robin Murphy
2020-10-22 17:14 ` [PATCH v5 0/3] iommu/arm-smmu-qcom: Support maintaining bootloader mappings Steev Klimaszewski
2020-10-29 18:34 ` Will Deacon
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